摘要:

The Society for Applied Spectroscopy... KEEP ABREAST OF NEW AND INNOVATIVE TECHNOLOGY .... Our Society can provide you with the latest in research technology and practical knowledge. We also provide the essential link for networking with your peers - with options such as a membership directory internet access and an annual conference. There are awards for achievements student programs and on-line services. Membership entitles you to receive a subscription to Applied Spectroscopy. This monthly publication features papers on all areas of spectroscopy and contains advertisements from leading companies in the field. It is a valuable resource for those who wish to remain informed of today's technology and research and for those providing quality resource materials. You will be eligible to receive reduced rates on other scientific j o d s e.g.Spectrochemical Acta B JAAS and Analyfical Chemistry. Receive a discount on the registration fees for FACSS the worlds' leading conference in spectroscopy and analytical chemistry. We provide educational courses at a discount to members which can be used as a tool to increase on-the-job performance. Learn fundamental and practical instrumentation analflcal methodology and sample applications through these educational courses. We are confident you will be impressed and will want to become a member of our prestigious Society. We look forward to hearing from you in the near future. Please fill out the form below and fax or mail it to SAS OOl(301) 694-8122 - Phone 201 B Broadway Street OOl(301) 694-6860 - FU Frederick MD.21701 USA TinaKs@aol.com - E-mail YES enroll me as an SAS member today! 8 m 8 RATES - USA CANADA OUTSIDE USA MEMBER $65.00 $80.00 $105.00 RETIREE $20.00 8 STUDENT $20.00 $35.00 $ 60.00 Please circle one! 8 8 m Company 8 ' Address 8 Province postal code country 8 8 Phone Fax E-mail (include country code) 8 8 m MY position fits the following category OAcademic OInstrument Company OConsultant OGovernment ORetiree OStudent OClinical Lab OCommercial Lab OIndustrY(TYPe 1 OOther Mycheckisenclosed 0 Invoice Me 0 Bill my MCNISNAMX 0 8 m 8 8 m 8 m m m 8 8 8 8 8 Credit Card Number Expiration Date 8 Signature 8 8 8 m 8 8 8 CHECKS MUST BE IN US FUNDS DRAWN ON A US BANK! 8 JAASPROM mThe Society for Applied Spectroscopy... KEEP ABREAST OF NEW AND INNOVATIVE TECHNOLOGY ....Our Society can provide you with the latest in research technology and practical knowledge. We also provide the essential link for networking with your peers - with options such as a membership directory internet access and an annual conference. There are awards for achievements student programs and on-line services. Membership entitles you to receive a subscription to Applied Spectroscopy. This monthly publication features papers on all areas of spectroscopy and contains advertisements from leading companies in the field. It is a valuable resource for those who wish to remain informed of today's technology and research and for those providing quality resource materials. You will be eligible to receive reduced rates on other scientific j o d s e.g.Spectrochemical Acta B JAAS and Analyfical Chemistry. Receive a discount on the registration fees for FACSS the worlds' leading conference in spectroscopy and analytical chemistry. We provide educational courses at a discount to members which can be used as a tool to increase on-the-job performance. Learn fundamental and practical instrumentation analflcal methodology and sample applications through these educational courses. We are confident you will be impressed and will want to become a member of our prestigious Society. We look forward to hearing from you in the near future. Please fill out the form below and fax or mail it to SAS OOl(301) 694-8122 - Phone 201 B Broadway Street OOl(301) 694-6860 - FU Frederick MD. 21701 USA TinaKs@aol.com - E-mail YES enroll me as an SAS member today! 8 m 8 RATES - USA CANADA OUTSIDE USA MEMBER $65.00 $80.00 $105.00 RETIREE $20.00 8 STUDENT $20.00 $35.00 $ 60.00 Please circle one! 8 8 m Company 8 ' Address 8 Province postal code country 8 8 Phone Fax E-mail (include country code) 8 8 m MY position fits the following category OAcademic OInstrument Company OConsultant OGovernment ORetiree OStudent OClinical Lab OCommercial Lab OIndustrY(TYPe 1 OOther Mycheckisenclosed 0 Invoice Me 0 Bill my MCNISNAMX 0 8 m 8 8 m 8 m m m 8 8 8 8 8 Credit Card Number Expiration Date 8 Signature 8 8 8 m 8 8 8 CHECKS MUST BE IN US FUNDS DRAWN ON A US BANK! 8 JAASPROM m

ISSN:0267-9477    

DOI:10.1039/JA99611BP003

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Journal of Analytical Atomic Spectrometry 111 111111111 111111 111 111111111 111111 THE ROYAL C H EM I ST RY Information Services I I JASPE2 11 (1 2) 53N-58N 11 29-1 234 461 R-522R CONTENTS NEWS PAGES Editorial-Steve J. Hill Guest Editors Foreword-Joseph A. Caruso Steve J. Hill Diary of Conferences and Courses Future Issues 53N 53N 54N 55N 57N PAPERS Trace Metal Speciation via Supercritical Fluid Extraction-Liquid Chromatography-Inductively Coupled Plasma Mass Spectrohetry Nohora P. Vela Joseph A. Caruso Low-flow Interface for Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry Speciation Using an Oscillating Capillary Nebulizer Lanqing Wang Sheldon W. May Richard F. Browner Stanley H. Pollock 1129 1137 Effect of Different Spray Chambers on the Determination of Organotin Compounds by High-performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry Cristina Rivas Les Ebdon Steve J.Hill 1147 Feasibility Study of Low Pressure Inductively Coupled Plasma Mass Spectrometry for Qualitative and Quantitative Speciation Gavin O’Connor Les Ebdon E. Hywel Evans Hong Ding Lisa K. Olson Joseph A. Caruso 1151 Speciation of Inorganic Selenium and Selenoaminoacids by On-line Reversed- phase High-performance Liquid Chromatography-Focused Microwave Digestion-Hydride Generation-atomic Detection J. M. Gonzalez Lafuente M. L. Fernandez Sanchez A. Sanz-Medel 11 63 Speciation of Organic Selenium Compounds by High-performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry in Natural Samples Riansares MuAoz Olivas Olivier F.X. Donard Nicole Gilon Martine Potin-Gautier Investigation of Selenium Speciation in In Vitro Gastrointestinal Extracts of Cooked Cod by High-performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry and Electrospray Mass Spectrometry Helen M. Crews Philip A. Clarke D. John Lewis Linda M. Owen Paul R. Strutt Andres lzquierdo Approaches to the Determination of Metallothionein(s) by High-performance Liquid Chromatography-Quartz Tube Atomic Absorption Spectrometry Yanxi Tan Patrick Ager William D. Marshall Hing Man Chan Speciation of Some Metals in River Surface Water Rain and Snow and the Interactions of These Metals With Selected Soil Matrices J. Y. Lu C. L. Chakrabarti M. H. Back A. L. R. Sekaly D. C. Gregoire W. H.Schroeder 1171 1177 1183 1189 Investigations Into Chromium Speciation by Electrospray Mass Spectrometry Ian 1. Stewart Gary Horlick Arsenic Speciation by Liquid Chromatography Coupled With lonspray Tandem Mass Spectrometry Jay J. Corr Erik H. Larsen 1203 1215 Atomic Spectrometry Hyphenated to Chromatography for Elemental Speciation Performance Assessment Within the Standards Measurements and Testing Programme (Community Bureau of Reference) of the European Union Philippe Quevauviller CUMULATIVE AUTHOR INDEX 1225 1233 AT0 M I C SPECTROMETRY UPDATES Industrial Analysis Metals Chemicals and Advanced Materials- James S. Crighton John Carroll Ben Fairman Janice Haines Mike Hinds 461 R References Typeset printed and bound by The Charlesworth Group Huddersfield England 01484 51 7077 509R 0267-9477(1996112:1-6Journal of Analytical Atomic Spectrometry 111 111111111 111111 111 111111111 111111 THE ROYAL C H EM I ST RY Information Services I I JASPE2 11 (1 2) 53N-58N 11 29-1 234 461 R-522R CONTENTS NEWS PAGES Editorial-Steve J.Hill Guest Editors Foreword-Joseph A. Caruso Steve J. Hill Diary of Conferences and Courses Future Issues 53N 53N 54N 55N 57N PAPERS Trace Metal Speciation via Supercritical Fluid Extraction-Liquid Chromatography-Inductively Coupled Plasma Mass Spectrohetry Nohora P. Vela Joseph A. Caruso Low-flow Interface for Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry Speciation Using an Oscillating Capillary Nebulizer Lanqing Wang Sheldon W. May Richard F. Browner Stanley H. Pollock 1129 1137 Effect of Different Spray Chambers on the Determination of Organotin Compounds by High-performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry Cristina Rivas Les Ebdon Steve J.Hill 1147 Feasibility Study of Low Pressure Inductively Coupled Plasma Mass Spectrometry for Qualitative and Quantitative Speciation Gavin O’Connor Les Ebdon E. Hywel Evans Hong Ding Lisa K. Olson Joseph A. Caruso 1151 Speciation of Inorganic Selenium and Selenoaminoacids by On-line Reversed- phase High-performance Liquid Chromatography-Focused Microwave Digestion-Hydride Generation-atomic Detection J. M. Gonzalez Lafuente M. L. Fernandez Sanchez A. Sanz-Medel 11 63 Speciation of Organic Selenium Compounds by High-performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry in Natural Samples Riansares MuAoz Olivas Olivier F.X. Donard Nicole Gilon Martine Potin-Gautier Investigation of Selenium Speciation in In Vitro Gastrointestinal Extracts of Cooked Cod by High-performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry and Electrospray Mass Spectrometry Helen M. Crews Philip A. Clarke D. John Lewis Linda M. Owen Paul R. Strutt Andres lzquierdo Approaches to the Determination of Metallothionein(s) by High-performance Liquid Chromatography-Quartz Tube Atomic Absorption Spectrometry Yanxi Tan Patrick Ager William D. Marshall Hing Man Chan Speciation of Some Metals in River Surface Water Rain and Snow and the Interactions of These Metals With Selected Soil Matrices J. Y. Lu C. L. Chakrabarti M. H. Back A. L. R. Sekaly D. C. Gregoire W. H. Schroeder 1171 1177 1183 1189 Investigations Into Chromium Speciation by Electrospray Mass Spectrometry Ian 1. Stewart Gary Horlick Arsenic Speciation by Liquid Chromatography Coupled With lonspray Tandem Mass Spectrometry Jay J. Corr Erik H. Larsen 1203 1215 Atomic Spectrometry Hyphenated to Chromatography for Elemental Speciation Performance Assessment Within the Standards Measurements and Testing Programme (Community Bureau of Reference) of the European Union Philippe Quevauviller CUMULATIVE AUTHOR INDEX 1225 1233 AT0 M I C SPECTROMETRY UPDATES Industrial Analysis Metals Chemicals and Advanced Materials- James S. Crighton John Carroll Ben Fairman Janice Haines Mike Hinds 461 R References Typeset printed and bound by The Charlesworth Group Huddersfield England 01484 51 7077 509R 0267-9477(1996112:1-6

ISSN:0267-9477    

DOI:10.1039/JA99611FX013

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

DIARY OF CONFERENCES AND COURSES 1996 ASMS Short Course Interpretation of Mass Spectra LC-MS and MS-MS May 11-12 Portland OR USA For further details contact American Society of Mass Spectrometry 1201 Don Diego Avenue Santa Fe NM 87505 USA. Telephone + 1 505 989 4517; Fax +1 505 989 1073. 44th ASMS Conference on Mass Spectrometry and Allied Topics May 12-17 Portland OR USA For further details contact American Society of Mass Spectrometry 1201 Don Diego Avenue Santa Fe NM 87505 USA. Telephone +1 505 989 4517; Fax +1 505 989 1073. 4th International Symposium on Metal Ions in Biology and Medicine May 19-22 TarragonalBarcelona Spain For further details contact Mercedes Gomez Laboratory of Toxicology and Biochemistry School of Medicine c/San Lorenzo 21 E-43201 Reus Spain. Telephone +34 77 759376; Fax +34 77 759322.9th International Symposium on Trace Elements in Man and Animals May 19-24 Ban8 Alberta Canada Details can be found[ in J. Anal. At. Spectrom. 1995 10 58N. For further details contact TEMA-9 The Banff Centre for Conferences P.O. Box 1020 Station 131 Banff Alberta Canada TOL OCO. Telephone + 1 403 762 6308; Fax +1 4.03 762 6388 or Dr Mary L'AbbC. Telephone +1 613 957 0924; Fax i-1 613 941 6182; E-mail Mlabbe@HPB.HWC.CA. 2nd European Furnace Symposium May 26-30 St. Petersburg Russia For further details contact Boris L'vov St. Petersburg Technical University Analytical Chemistry Department Politechnicheskaya 29 St. Petersburg 195251 Russia. Fax +7 812 552 7590; E-mail lvlvr gachem. s tu. spb. su. Total Reflection X-Ray Fluorescence Analysis June 10-11 (Part 1 ) Eindhoven Germanji June 13-14 (Part 2) Dortmund Germany Details can be found in J.Anal. At. Spectrom. 3995 10 60N. For further details contact Gesellschaft Deutscher Chemiker TXRF-Konferenz Postfach 90 04 40 D-60444 Frankfurt Germany. Fax + 49 69 7917 475. 20th International Symposium on High Performance Liquid Phase Separations June 16-21 Sun Francisco CA USA For further details contact Janet Cunningham Barr Enterprises P.O. Box 279 Walkersville MD 21793 USA. Telephone +1 301 898 3772; Fax + l 301 898 5596; E-mail h ttp://www. hpl hp.com/hplc9 6. Resonance Ionization Spectroscopy June 30-July 5 Pennsylvania USA Details can be found in J. Anal. At. Spectrom. 1995 10 60N. For further details contact Sabrina Glasgow Conference Secretary Department of Chemistry The Pennsylvania State University 184 Materials Research Institute Building University Park PA 16802-7003 USA.Telephone + 1 814 865 0200; Fax + 1 814 863 0618; E-mail scg4@psuvm.psu.edu. 4th European Conference on Thermal Plasma Processes July 15-17 Athens Greece For further details contact Dimitrios Rapakoulias Chemical Engineering Department University of Patras P.O. Box 1470 Rio Patras Greece. Telephone +30 61 993361 997857; E-mail http://armodios.chemeng.upatras.gr. 14 N Journal of Analytical Atomic Spectrometry April 1996 Vol.11Eighth Biennial National Atomic Spectroscopy Symposium July 17-19 Norwich UK Details can be found in J. Anal. At. Spectrom. 1995 10 60N. For further details contact Ms Brenda Holliday BNASS Secretariat Royal Society of Chemistry Thomas Graham House Science Park Milton Road Cambridge CB4 4WF UK.Telephone + 44 (0) 1223 420066; Fax + 44 (0) 1223 423623; E-mail hollidayb@rsc.org. International Symposium on Optical Science Engineering Instrumentation August 4-9 Denver CO USA For further details contact SPIE P.O. Box 10 Bellingham WA 98227-0010 USA. Telephone +1 360 676 3290; Fax + 1 360 647 1445; E-mail spie@spie.org. 42nd International Conference on Analytical Science and Spectroscopy August 10-13 London Ontario Canada For further details contact Martin Stillman University of Western Ontario Department of Chemistry London ON N6A 5B7 Canada. Telephone + 1 519 661 3821; Fax + 1 519 661 3022; E-mail stillman@uwo.ca. Gordon Research Conference on Plasma Processing Science August 11-16 New Hampton NH USA For further details contact S.L.Girshick University of Minnesota Department of Mechanical Engineering 111 Church St. S. Minneapolis MN 55455 USA. Telephone + 1 612 625 5315; Fax +1 612 624 1398; E-mail sig@maroon. tc.umn.edu. Euroanalysis IX September 1-7 Bologna Italy For further details contact L. Gabbatini Dipartimento de Chimica Universita di Bari Via Orabona 4 1-70126 Bari Italy. Telephone +39 80 5442020; Fax +39 80 5442026. PRAHA96 14th International Conference on High Resolution Molecular Spectroscopy September 9-13 Prague Czech Republic For further details contact Dr Vladimir Spriko Academy of Sciences of the Czech Republic J. Heyrovsky Institute of Physical Chemistry Dolejskova 3 CZ-18223 Praha 8 Czech Republic.Fax +42 2 858 2307; E-mail 12th Asilomar Conference on Mass Spectrometry Elemental Mass Spectrometry praha96@jh-inst.cas.cz or praha96awcpj .chemie.uni-wuppertal.de. International Symposium on Biological Monitoring in Occupational and Environmental Health September 11-13 Espoo Finland For further details contact Kristiina Kulha Finnish Institute of Occupational Health Topeliuksenkatu 41 a A FIN-00250 Helsinki Finland. Telephone +358 0 4747-551; Fax +358 0 4747 548; E-mail kku@occuphealth.fi ht tp://www. occuphealt h.fi. 21st International Symposium on Chromatography September 15-20 Stuttgart Germany For further details contact Gesellschaft Deutscher Chemiker Abteilung Tagunen Postfach 900440 D-60444 Frankfurt am Main Germany. Telephone +49 69 7917 360; Fax +49 69 7917 475.1996 European Workshop on Chemometrics September 15-20 Bristol UK For further details contact Caroline Hutcheon Bristol Chemometrics School of Chemistry University of Bristol Bristol BS8 lTS UK. Telephone +44 (0) 117 928 9000 ext. 4421 (ansaphone) or +44 (0)117 928 7658; Fax +44 (0)117 925 1295. International Ion Chromatography Symposium September 16-19 Reading UK For further details contact Century International P.O. Box 493 Medfield MA 02052 USA. Telephone + 1 508 359 8777; Fax +1 508 359 8778. Phil Jones Department of Environmental Sciences University of Plymouth Drake Circus Plymouth Devon PL4 8AA UK. Telephone +44 (0)1752 233000; Fax +44 (0)1752 233035. 5th International Conference on Plasma Source Mass Spectrometry September 16-20 Durham UK For further details contact Dr Grenville Holland Department of Geological Sciences Science Laboratories University of Durham South Road Durham City DH1 3LE UK.Fax +44 (0)191 374 2510. September 20-24 Pacijic Grove CA USA For further details contact American Society of Mass Spectrometry 1201 Don Diego Avenue Santa Fe NM 87505 USA. Telephone +1 505 989 4517; Fax + 1 505 989 1073. 12th ICP-MS Applications Meeting September 23-24 Julich Germany For further details contact Dr J. S. Becker Forschungszentrum Jiilich Gm bH Zen t rala b teilung fur C hemische Analysen D-52425 Julich Germany. Telephone +49 2461 612698; Fax +49 2461 612560. Mass Spectrometry Processes for the Determination of Trace Element September 24-26 Julich Germany For further details contact Dr J. S.Becker Forschungszentrum Jiilich GmbH Zentralabteilung fur Chemische Analysen D-52425 Jiilich Germany. Telephone +49 2461 612698; Fax +49 2461 612560. 23rd Annual Conference of the Federation of Analytical Chemistry and Spectroscopy Societies (FACSS) September 29-October 4 Kansas City MO USA For further details contact FACSS 201B Broadway Street Frederick MD 21701-6501 USA. Telephone + 1 301 846 4797. International Exhibition and Conference for Chemical Technology Analytical Technology and Biotechnology November 12-15 Basel Switzerland For further details contact L. E. Loew ilmac96 Messe Bassel. P.O. Box CH-4021 Basel Switzerland. Telephone +41 61 686 2707; Fax 1-41 61 686 3 1 QQ Fourth Rio Symposium on Atomic Spectrometry November 24-30 Buenos Aires Argentina For further details contact Dr Osvaldo E.Troccoli Quimica Analitica Facultad de Ciencias Exactas y Naturales Ciudad Universitaria ( 1428) Buenos Aires Argentina. Telephone +541 783 3025; Fax +541 782 0441. Journal of Analytical Atomic Spectrometry April 1996 Vol. 11 15N1997 1997 European Winter Conference on Plasma Spectrochemistry January 12-17 Gent Belgium For further details contact L. Moens Secretariat 1997 European Winter Conference Laboratory of Analytical Chemistry University of Gent Proeftuinstraat 86 B-9000 Gent Belgium. Telephone +32 9 264 66 00; Fax +32 9 264 66 99; E-mail plasma97@rug.ac.be. Updated information may be obtained from the '97 Winter Conference homepage on the World Wide Web at http://www.rug.ac.be. CANAS '97 Colloquium Analytische At omspek tr 0s kopie March 9-14 FreiberglSachsen Germany For further details contact G.Werner Universitat Leipzig Institut fur Analytische Chemie Linnestrasse 3 D-04103 Leipzig Germany. Telephone +49 0341 973 6101; Fax +49 0341 973 6115. 48th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy March 16-21 Atlanta GA USA For further details contact Linda Briggs The Pittsburgh Conference 300 Penn Center Blvd. Suite 332 Pittsburgh PA 15235-5503 USA. Telephone + 1 412 825 3220 + 1 800 825 3221; Fax +1 412 825 3224. Seventh International Symposium on Biological and Environmental Reference Materials April 21-25 Ant werp Belgium Details can be found in J. Anal. At. Spectrom. 1995 9 54N. For further details contact Dr J. Pauwels Institute for Reference Materials & Measurements Management of Reference Materials Unit Retieseweg B-2440 Geel Belgium.Telephone -t 32 14 571 722; Fax +32 14 590 406; or Wayne R. Wolf Ph.D. Food Composition Laboratory IJSDA 10300 Baltimore Blvd. Beltsville MD 20705 USA. Telephone + 1 301 504 8927; Fax + 1 301 504 8314. International conference on Analytical Chemistry June 15-21 Moscow Russia For further details contact Scientific Council on Chromatsgraphy RAS Lenensky Prospect 3 1 1179 15 Moscow Russia. Telephone + 7 095 952 0065; Fax + 7 095 952 0065; E-mail larionov@lmm.phyche.msk.su. International Symposium on Optical Science Engineering Instrumentation July 18-23 San Diego California For further details contact SPIE P.O. Box 10 Bellingham WA 98227-0010 USA. Telephone +1 360 676 3290; Fax + 1 360 647 1445; E-mail spie@spie.org. XXX Colloquium Spectroscopicum Internationale September 2 1-26 Melbourne Australia Details can be found in J. Anal. At. Spectrom. 1995 10 58N. For further details contact The Meeting Planners 108 Church Street Hawthorn Victoria 3122 Australia. Telephone +61 3 9819 3700; Fax +61 3 9819 5978. Updated information may be obtained from the XXX CSI homepage on the World Wide Web at http://www.latrobe.edu.au/CSIconf/ XXXCSI.htm1. 24th Annual Meeting of the Federation of Analytical Chemistry and Spectroscopy Societies September 21-26 Cleveland OH USA For further details contact FACSS National Office 201B Broadway St. Frederick MD 21701-6501 USA. Telephone + 1 301 694 8122; Fax + 1 301 694 6860; E-mail j brownsas@aol.com. 16N Journal of Analytical Atomic Spectrometry April 1996 Vol. 1 1

ISSN:0267-9477    

DOI:10.1039/JA996110014N

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

).{ ROYAL AUSTRALIAN CHEMICAL INSTITUTE AUSTRALIAN ACADEMY OF SCIENCE v XXX COLLOQUIUM SPECTROSCOPICUM INTERNATIONALE World Congress Centre Melbourne Australia September 21st-26th 1997 Participants are invited to submit contributions for presentation on the following topics; Theory Techniques and Instrumentation of :- Atomic Spectroscopy (Emission Absorption Fluorescence) Computer Applications and Chemometrics Electron Spectroscopy Gamma Spectroscopy Laser Spectroscopy Luminescence Spectroscopy Mass Spectrometry (Inorganic and Organic) Methods of Surface Analysis and Depth Profiling UVNisible Spectroscopy NIR Spectroscopy IR Spectroscopy Mossbauer Spectroscopy Nuclear Magnetic Resonance Spectrometry Photoacoustic and Photothermal Spectroscopy Raman Spectroscopy X-Ray Spectroscopy Applications of Spectroscopy to the Analysis of :- Biological and Environmental Samples Food and Agricultural Products Metals Alloys and Geological Materials Industrial Processes and Products Plenary and Invited Speakers To date the following eminent spectroscopists have accepted invitations to present keynote lectures; Freddy Adams Mike Adams Mike Blades John Chalmers Bruce Chase Peter Fredericks Manfred Grasserbauer Mike Gross Mike Guilhaus Peter Hannaford Gary Hieftje Kazuhiro Imai Hiroshi Masuhara Belgium UK Canada UK USA Australia Austria USA Australia Australia USA Japan Japan Andrew Zander Russell McLean Jean-Michel Mermet Caroline Mountford Nicolo Omenetto Mike Ramsey Alfredo Sanz Medel Margaret Sheil Heinz Siesler Richard Snook Yngvar Thomassen Bernhard Welz John Williams Barry Sharp USA Australia France Australia IdY USA Spain UK Australia Germany UK Norway Germany UK In connection with the XXX CSI a number of pre-symposia will be organised the conference will feature an exhibition of the latest spectroscopic instrumentation and associated equipment.Social Programme The scientific programme will be punctuated with memorable :social events and excursions of scientific cultural and tourist interest. The social programme is open to all participants and accompanying persons. sponsors As at August 1995 the following companies have agreed to be major sponsors of XXX CSI 1997; GBC Hewlett-Packard Perkin Elmer and Varian For farther information contact - Secretary Mr P.L. Larkins CSIRO Division of Materials Science & Technology Private Bag 33 Rosebank MDC Clayton VIC 3169 AUSTRALIA Telephone +61 3 95422003 Facsimile +61 3 95441 128 E-mail larkins@rivett.mst.csiro.au Conference Secretariat The Meeting Planners 108 Church Street Hawthorn VIC 31 22 AUSTRALIA Telephone +61 3 98193700 Facsimile +61 3 98195978 Updated information may be obtained from the XXX CSI homepage on the World Wide Web at http://w w w.latro be. edu. au/CSIconf/XXX&I. htm 1 QANTAS has been appointed the sole official carrier to the XXX CSI 1997. When making QANTAS reservations please quote JIF 73Q. The Analyst and JAAS have been appointed as the official journals for publications resulting from CSI ‘97. Authors are encouraged to bring their manuscripts to the conference.).{ ROYAL AUSTRALIAN CHEMICAL INSTITUTE AUSTRALIAN ACADEMY OF SCIENCE v XXX COLLOQUIUM SPECTROSCOPICUM INTERNATIONALE World Congress Centre Melbourne Australia September 21st-26th 1997 Participants are invited to submit contributions for presentation on the following topics; Theory Techniques and Instrumentation of :- Atomic Spectroscopy (Emission Absorption Fluorescence) Computer Applications and Chemometrics Electron Spectroscopy Gamma Spectroscopy Laser Spectroscopy Luminescence Spectroscopy Mass Spectrometry (Inorganic and Organic) Methods of Surface Analysis and Depth Profiling UVNisible Spectroscopy NIR Spectroscopy IR Spectroscopy Mossbauer Spectroscopy Nuclear Magnetic Resonance Spectrometry Photoacoustic and Photothermal Spectroscopy Raman Spectroscopy X-Ray Spectroscopy Applications of Spectroscopy to the Analysis of :- Biological and Environmental Samples Food and Agricultural Products Metals Alloys and Geological Materials Industrial Processes and Products Plenary and Invited Speakers To date the following eminent spectroscopists have accepted invitations to present keynote lectures; Freddy Adams Mike Adams Mike Blades John Chalmers Bruce Chase Peter Fredericks Manfred Grasserbauer Mike Gross Mike Guilhaus Peter Hannaford Gary Hieftje Kazuhiro Imai Hiroshi Masuhara Belgium UK Canada UK USA Australia Austria USA Australia Australia USA Japan Japan Andrew Zander Russell McLean Jean-Michel Mermet Caroline Mountford Nicolo Omenetto Mike Ramsey Alfredo Sanz Medel Margaret Sheil Heinz Siesler Richard Snook Yngvar Thomassen Bernhard Welz John Williams Barry Sharp USA Australia France Australia IdY USA Spain UK Australia Germany UK Norway Germany UK In connection with the XXX CSI a number of pre-symposia will be organised the conference will feature an exhibition of the latest spectroscopic instrumentation and associated equipment.Social Programme The scientific programme will be punctuated with memorable :social events and excursions of scientific cultural and tourist interest. The social programme is open to all participants and accompanying persons. sponsors As at August 1995 the following companies have agreed to be major sponsors of XXX CSI 1997; GBC Hewlett-Packard Perkin Elmer and Varian For farther information contact - Secretary Mr P.L. Larkins CSIRO Division of Materials Science & Technology Private Bag 33 Rosebank MDC Clayton VIC 3169 AUSTRALIA Telephone +61 3 95422003 Facsimile +61 3 95441 128 E-mail larkins@rivett.mst.csiro.au Conference Secretariat The Meeting Planners 108 Church Street Hawthorn VIC 31 22 AUSTRALIA Telephone +61 3 98193700 Facsimile +61 3 98195978 Updated information may be obtained from the XXX CSI homepage on the World Wide Web at http://w w w. latro be. edu. au/CSIconf/XXX&I. htm 1 QANTAS has been appointed the sole official carrier to the XXX CSI 1997. When making QANTAS reservations please quote JIF 73Q. The Analyst and JAAS have been appointed as the official journals for publications resulting from CSI ‘97. Authors are encouraged to bring their manuscripts to the conference.

ISSN:0267-9477    

DOI:10.1039/JA99611BX015

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

FUTURE ISSUES WILL INCLUDE- Determination of Selenocystine Selenomethionine Selenite and Selenate by High Performance Liquid Chromatography Coupled to Inductively Coupled Plasma Mass Spectrometry-Angeles Quijano Ana M. Gutierrez Concepcion Perez-Conde Carmen Camara Analytical Parameters of Ethanol Solutions in a 40 MHz Inductively Coupled Plasma Optical Emission Spectrometer -Ro bert I. McCrindle Cornelius J. Rademeyer Laser Ablation Inductively Coupled Plasma Mass Spectrometry With a Time-of-flight Mass Analyser-Patrick P. Mahoney Gangqiang Li Gary M. Hieftje Determination of Trace Amounts of Sulfur in Steel by Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry-Hirohito Naka D. Conrad Gregoire Laser Ablation Inductively Coupled Plasma Mass Spectrometric Transient Signal Data Acquisition and Analyte Concentration Calculation-Henry P.Longerich Simon E. Jackson Detlef Gunther Multi-element Characterization of Titanium Dioxide by Electrothermal Atomic Absorption Spectrometry Inductively Coupled Plasma Atomic Emission Spectrometry Inductively Coupled Plasma Mass Spectrometry and Total Reflection X-ray Fluorescence After Matrix-Analyte Separation- V. Krivan Dieter Wildhagen B. Gercken J. Pave1 Equilibrium Plasma Composition in U- shaped DC Argon Stabilized Arc- M. Tripkovic I. D. Holclajtner- Antunovic Gordana Malovic Zoran Raspopovic COPIES OF CITED ARTICLES The Royal Society of Chemistry Library can usually supply copies of cited articles. For further details contact The Library Royal Society of Chemistry Burlington House Piccadilly London W1V OBN UK. Tel +44 (0) 71-437 8565; fax +44 (0) 71-287 9798; Telecom Gold 84; BUR210; Electronic Mailbox (Internet) LIBRARY@RSC.ORG. If the material is not available from the Society’s Library the staff will be pleased to advise on its availability from other sources. Please note that copies are not available from the RSC at Thomas Graham House Cambridge. 16N Journal of Analytical Atomic Spectrometry April 1996 Vol. 1 1

ISSN:0267-9477    

DOI:10.1039/JA996110016N

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Atomic Spectrometry Update- Clinical and Biological Materials Food and Beverages Atomic Spectrometry Update ANDREW TAYLOR* Supra-Regional Assay Service Metals Reference Laboratory Robens Institute of Industrial and Environmental Health and Safety University of Surrey Guildford Surrey UK GU XH SIMON BRANCH. The Lord Rank Centre R.H.M. Technology Lincoln Road High Wycombe Buckinghamshire UK HP QR HELEN M. CREWS Ministry of Agriculture Fisheries and Food CSL Food Science Laboratory Norwich Research Park Colney Lane Norwich UK NR UQ DAVID J. HALLS Trace Element Unit Department of Clinical Biochemistry Glasgow Royal Injrmary University NHS Trust Castle Street Glasgow UK G OSF MARK WHITE Health and Safety Laboratory Broad Lane Shefield UK S HQ SUMMARY OF CONTENTS. General Reviews. Sampling and Sample Preparation. Developments in Multi-element Analysis. Atomic emission spectrometry with the inductively coupled plasma the direct current plasma and the microwave induced plasma. Inductively coupled plasma mass spectrometry and other mass spectrometric techniques. X-ray fluorescence spectrometry. Other multi-element techniques and studies. Developments in Single ElementTechniques. Reference Materials and Quality Assessment. Hair and Nail Analysis. Drugs and Pharmaceuticals. Marine and Freshwater Biology. Progress for Individual Elements. Aluminium. Antimony. Arsenic. Barium. Beryllium. Bismuth. Boron. Cadmium. Calcium. Chromium. Cobalt. Copper. Germanium. Gold. Indium. Iodine. Iron. Lead. Lithium. Magnesium. Manganese. Mercury. Molybdenum. Nickel Analysis of Clinical and Biological Materials ~ * Review Co-ordinator to whom correspondence should be addressed t Present address Life Science Unit Environmental Institute Joint Research Centre - Ispra VA Italy. Platinum. Rare earths. Ruthenium. Selenium. Silicon. Silver. Sodium and potassium. Strontium.Tellurium. Tin. Titanium. Thorium and uranium. Vanadium. Zinc. Conclusions Table. Summary of Analysis of Clinical and Biological Materials Analysis of Foods and Beverages Sampling and Sample Preparation Direct determination of analytes Preconcentration Digestion Direct solid and slurry sampling Speciation Studies Developments in Methodology for Flame Atomic Absorption Spectrometry Developments in Methodology for Electrothermal Atomic Absorption Spectrometry Developments in Methodology for Inductively Coupled Plasma Mass Spectrometry Progress for Individual Elements Arsenic Boron Chromium Mercury Iodine SeleniumTin Single and Multi-element Analysis of Foods Contributions From Foil Packaging Materials Dietary Intake Studies Characterization Studies Reference Materials and Collaborative Trials Table. Summary of Analyses of Foods and Beverages Journal of Analytical Atomic Spectrometry April Vol. R-R R This Update spans all the abstracts listed in the issues of JAAS -. Developments in sample preparation enrichment continued apace. Many of these involved FI and were usually coupled directly to the analytical instrument for on-line measurements. In our recent Updates accelerator M S for investigations of A physiology has been featured; this year we saw the application of the technique to Ca and other elements.The ever-present interest in lead exposure among children has prompted construction of simple semi-portable instruments with electrothermal atomizers dedicated to measurement of Pb in blood. These emerged at Pittcon and were also shown at later conferences. Investigations of trace element nutrition and metabolism using stable isotopes and mass spectrometric methods have been reported in the past but this year saw the publication of a comprehensive review of this important topic. A number of papers from the Fifth Nordic Symposium on Trace Elements in Human Health and Disease were published in. The Analyst including two which described endemic arsenic toxicity in West Bengal. As the source of exposure was naturally contaminated drinking water this tragic situation must have been ongoing for many years and it is surprising that information has only recently been forthcoming. ANALYSIS O F CLINICAL AND BIOLOGICAL MATERIALS David J. Halls AndrewTaylor and Mark White This review on applications of atomic spectrometry to the analysis of clinical and biological materials covers published papers and conference presentations appearing in the year approximately ending August,. Many of the trends observed in previous Updates have continued. Further develop- ments have taken place in on-line sample preparation. Speciation studies have exploited the sensitivity of ICP-MS as a detector. Generally ICP-MS is becoming a more widely used technique not principally for multi-element analysis but for determination of more difficult elements and for stable isotope studies.The elements of main interest continue to be Al As Hg Pb and Se. Summaries of methods and techniques used are given in Table. General Reviews Two reviews have called for further development of speciation as the main challenge for future years particularly for clinical and biological samples. Sanz-Medel's lecture at the Fifth Nordic Symposium on Trace Elements in Human Health and Disease in Loen Norway has been published with examples of work from his own laboratory. A similar theme was raised by Caruso C at the FACSS meeting in St. Louis USA focusing particularly on the coupling of separation techniques with ICP-MS. Our previous Updates for and covered developments in the analysis of clinical and biological materials foods and beverages by atomic spectrometry. Sampling and Sample Preparation.The first important consideration in analysis is how to take a sample representative of the material to be analysed without introducing any contamination. Vereby et al. re-evaluated the old method of blood spots on filter-paper for collecting and storing samples from children for blood Pb determination. If the child's finger was thoroughly cleaned before pricking if the filter-paper used was free of Pb and if the filter-paper samples were stored in plastic bags then results were obtained by Delves cup FAAS that were comparable to those obtained with capillary blood samples and ETAAS. On samples the correlation coefficient was. although the R Journal of Analytical Atomic Spectrometry April slope of the line [Delves cup]=O. [ETAAS] +. pg dl-' suggests that one of the methods had a slight accuracy problem. Contamination of finger-prick samples was also addressed by Sargent et al.They demonstrated that a thin rubberized adhesive dressing over the finger formed an effective barrier to contamination from the skin surface. Bush et al. aimed to discover whether fixing in formalin affected tissue trace element concentrations and whether the elements were homogeneously distributed in human organs. Samples of tissue were digested in HN-H and Ca Cu Fe Mg and Zn determined by ICP-AES Hg by CVAAS As Cd Mn and Pb by ETAAS and A by ICP-MS. Long-term storage in formalin had little effect on most element concentrations except for Al which increased and Mn which decreased. Most elements were homogeneously distributed throughout brain liver and kidney. Exceptions were Cd and Hg in kidney and Al Ca Cu Fe Mg Mn and Zn in brain.The highest concentrations of the toxic elements were found in liver and kidney. Precipitates can appear in urine samples on storage. Burden et al. recommended diluting urines + with. mol -' HNO and then warming to °C to redissolve cations. Rat urines were diluted + + with % H and mol I-' HNO and then heated at °C for h. Further additions of H and HNO were made and the solu- tion again heated. Measurements of elements were made by For digestion of biological samples Sanchez and Millan demonstrated that an ultrasonic cleaning bath provid- ing ultrasound speeded up conventional wet ashing. In a comparison with a conventional digestion procedure for the determination of eight elements in BCR mussel tissue and rye grass CRMs results of similar accuracy and precision were obtained. Jung et al. compared three methods for the digestion of herbal drugs for the determination of Cd Cu and Pb dry ashing at "C followed by heating with concentrated HN wet ashing with HN-HC-HC and digesting in an autoclave with HNO at "C for h.The latter method gave the best recovery of analyte. For determination of Cu Hg and Pb in traditional Chinese medicines by AAS extraction by heating with % HNO for h was shown by Chow et al. to give good recovery and results which were comparable to dry ashing or wet digestion procedures. Amarasiriwardena et al. applied vapour-phase diges- tion with acid to the decomposition of small amounts of biological material. Samples were inserted into a quartz sample holder of volume. ml and placed in a conventional high pressure digestion vessel. Residual C was very low after diges- tion and satisfactory results were obtained on a range of elements when determined by ICP-AES. Optimization of microwave heated digestion processes was studied by Lan et al. using a chemometric orthogonal array design method. In the application of this approach to the determination of Se in biological samples by HGAAS the optimum conditions were. ml of HNO and. ml of HS and YO microwave power and heating for min.The results predicted no requirement for HClO, H or HPO. To determine Ba Ca Cd Fe K Mg Na Pb and Zn in bone and teeth Gil et al. first ashed samples at °C for. h in a muffle furnace. The material was then crushed to small fragments. About mg of the fine material were then placed in a digestion bomb with ml of HNO and the bomb was heated in a microwave oven at W for s. Results for the above elements in IAEA H- Animal Bone CRM were in agreement with certified values. In a comparison of convection and microwave heatingTahan et al. showed that bomb digestion of biological samples for total Hg gave equival- ent results by both heating approaches but convection heating required about h whereas microwave heating took about ICP-AES. t'ol. s. The methods were applied to the determination of Hg in whole blood and urine by CVAAS. Krushevska et al. demonstrated that a focused microwave digestion system oper- ated at atmospheric pressure was very suitable for the digestion of milk total parenteral nutrition fluids tissues and urine for subsequent determination of a range of elements by ICP-AES. Residual C levels were similar to those obtained with high- pressure digestion and lower than those obtained with a closed medium-pressure microwave digestion system.The effect of different acid and reagent combinations and heating pro- grammes was examined. Developments in on-line digestion or reaction with microwave heating continue. Burguera et al. developed further their concept of a continuous FI system for blood from patient to analyser in an application to the determination of Co in whole blood by ETAAS. The blood sample was pumped directly from the vein on the forearm of a patient and mixed with. mol - HNO and EDTA. A time-based solenoid injector sampled a portion of this mixture and injected it into a carrier stream which was then pumped through a m coil in a microwave oven. Gases were subsequently removed in a gas diffusion cell and the solution was cooled in an ice chamber. An aliquot p of the stream was injected by a solenoid injector into an ETA.The autosampler of the ETAAS system then injected MgNO& as chemical modifier and the furnace programme began. The completely enclosed system reduced problems from contamination. In ten healthy subjects a mean Co concentration of.+. pg -l was found. A similar approach to digestion was employed by Welz et al. for on-line digestion for the determination of As by HGAAS. Pressure was allowed to build up in the line by a restrictor to improve the efficiency of digestion. Reduction of AsV to As"' with L-cysteine preceded hydride generation of ASH with NaBH,. The system could measure down to an LOD of. pg - and was applied to the determination of As in blood. In an automated digestion system built by Stewart and Barnes for a commercial focused microwave heater an ml digestion chamber was used into which sample and reagents were pumped.The flow was stopped heating power applied and then the digest pumped out. The system was applied to the determination of several metals in milk blood and urine by ICP-AES. For hydride generation of Se and subsequent determination by AAS or AFS Pitts et al. used an on-line microwave heating step to reduce SeV to Se" with HC. In their earlier approach Se" was determined by HGAAS; under the same conditions SeV' does not produce the hydride. Total Se was then determined after on-line reduction with HC and SeV' calculated as the difference of the two results. In their later development the species were separated by HPLC and the eluent treated with mol I-' HC and heated with focused microwave heating prior to the introduction of NaBH for hydride gener- ation. In this way both Se" and SeV' could be detected by AFS and a complete separation was achieved.The application of solid sampling ETAAS to the determi- nation of trace elements in tissues was reviewed by Herber. Direct solid and slurry sampling ETAAS was com- pared by Byrd and Butcher for the determination of Ag Cu Fe Mn Pb and Zn in NIST biological and environ- mental SRMs. Results by direct solid sampling were accurate but precision was poorer -% RSD than with slurry sampling -% RSD. Slurry sampling was generally accu- rate but gave a very low result for Cu in citrus leaves with poor precision. A newer approach to direct solid sampling is to use pre-ashing preliminary ashing to remove the bulk of the organic material.This also allows preconcentration of the analytes. Zhang et al. inserted samples into a miniature graphite cup and pre-ashed at °C for min for the determination of Pb in biological materials at the pg g- level. For direct determination of Se in human heart muscle Oilunkaniemi et al. used the cup-in-tube technique. Palladium with Cu and Triton X- was used as a chemical modifier and the calibration was with aqueous standards in % v v HNO,. Results on bovine liver and dogfish muscle CRMs were in agreement with certified values. Minami et al. proposed a new method for the calibration of solid sampling based on a three-point standard additions graph. It was found in the development of this approach for the determination of Cu that the calibration graph established for one type of biological material was suitable for other kinds of biological sample.The application of solid sampling ETAAS for certification purposes described by Hofmann et al. included the determination of Cd Pb and Zn in dogfish muscle. Preconcentration allows lower detection limits to be reached and thus less sensitive techniques like FAAS can be used for certain analyses. Standards Australia evaluated a method for the determination of Cd Cu and Pb in urine by FAAS after addition of KI-ascorbic acid solution and extrac- tion with trioctylamine into butyl acetate. Enrichment as a complex with APDC on activated charcoal enabled Aydenir and Gucer C to determine Ni in urine by FAAS. With a ml urine sample an LOD of. pg -' could be achieved.To improve LODs in ETAAS Sedykh et al. preconcentrated trace elements on to a Polyorgs YIIM sorbent with the help of ultrasound. The sorbent was separated by centrifugation rinsed and then suspended for slurry sampling. For Cd Co Cu Ni Pb and Se LODs of.,.,.,.,. and. pg l - l respectively were achieved. On-line sorbent preconcentration is attracting much interest although there seems to be an unnecessary proliferation of reagents used. Peng et a!. immobilized -hydroxyquinoline-sulfonic acid on an active carbon-silica gel substrate. This material in a microcolumn collected Al Cd Cu Fe and Mn at pH. These elements were then eluted with mol -' HC for determination by ICP-AES.The column could be used more than times. To demonstrate the technique the elements were determined in serum obtaining results which agreed with those obtained by ETAAS. To preconcentrate Cd Cu and Pb in biological and environmental samples by FI for determination by ETAAS Ma et al. used ammonium diethyldithiophosphate as a complexing agent masking any interference with citrate. Enrichment fac- tors of - led to LODs of.,. and. pg - for Cd Cu and Pb respectively. In order to preconcentrate A from tap water and dialysis fluids Martin-Esteban et al. used a microcolumn packed with Chromotrope B immobilized on AG -X ion exchange resin. Using a collection time of min an LOD of pg - was obtained by FAAS and with a collection time of min the LOD of ICP-MS was reduced to. pg -I. Peng et al. evaluated m- tetrakis -aminopheny porphyrin bonded on to an activated carbon-silica gel mixture for the preconcentration of elements for determination by ICP-AES. Copper Cd Fe Mn Ni and Pb were retained from samples buffered to pH. and subsequently eluted to give enhancement factors in the range -. Satisfactory analysis of NIST Pig Kidney SRM was demonstrated. Fang et al. examined the preconcentration of Cd from biological samples using FI systems. For FAAS the Cd was complexed with NaDDC and collected on the walls of a knotted reactor for subsequent elution with IBMK. An enhancement factor of could be achieved giving an LOD of. pg - '.The technique was applied to the determination of Cd in hair. For the determination of Cd in blood by ETAAS they used dithizone as the complexing agent sampling the digested blood sample for s at a flow of ml min-l to achieve an enrichment factor of and an LOD of. pg -'.In a Journal of Analytical Atomic Spectrometry April Vol. R further variation Dong and Fang used co-precipitation with Fe-APDC for the determination of Cd Co and Ni by FAAS.The precipitate collected on the knotted reactor was eluted with IBMK. The LODs were. and pg -' for Cd Co and Ni respectively. Application to NIST Bovine Liver SRM and a urine RM gave results in agreement with recommended values. In a later publication they applied the same co-precipitation technique to the deter- mination of Mo in human hair by ETAAS. Enrichment of -fold improved the LOD to. pg -'. Preconcentration could be carried out while the heating programme on the ETA was treating the previous sample. Interference from Cu could be overcome by addition of % thiourea to the sample solution. Developments in Multi-element Analysis. Atomic emission spectrometry with the inductively coupled plasma the direct current plasma and the microwave induced plasma Recent methods for the determination of elements in serum by ICP-AES use digestion of samples which seems a pity as others have demonstrated applications with simple dilution of samples. Zhang et al. digested placental serum with HNO,-HClO, evaporated digests to near dryness and re-dissolved in dilute HCl. It was claimed that elements could be determined. A similar digestion was used byTong and Hu for the determination of Ca Cu Fe K Mg Na P and Zn in serum. However Liu showed that essentially the same range of elements could be determined after a simple -fold dilution with %Triton X-. Concentrations of Sr in whole blood were determined by Piette et al. after microwave digestion of the samples. A mean concentration of.kO. pg -' f RSD was found for normal subjects by this method which had an LOD of. pg -'. Bauer et al. used the surfactant Triton X- to form a stable slurry of blood cells to determine B in whole blood by both ICP-AES and DCP-AES. Separation of protein- bound borocaptate species by HPLC and on-line detection by ICP-AES was described by Hotz and Bauer. An interesting approach was used by Nomizu et al. to determine Ca in individual blood cells. A cell suspension in a % C,H,OH-% H mixture was sprayed by a concen- tric nebulizer into a drying chamber before introduction into the plasma. Dilution of samples was used to ensure that each nebulizer droplet contained at most one cell.The pulses of emission at the.nm Ca line were amplified and fed to a multichannel pulse height analyser. The LOD of the system was. pg Ca in a cell; Ca concentrations found ranged from. to. pg. These researchers concluded that insufficient sensitivity limited the application to other elements and measurements for Mg Na and K were unsuccessful. Further development in improving the efficiency of introduction of cells into the plasma was needed through experimentation with alternative droplet generators. Andrasi et al. reported their methods and results on the analysis of human hrain samples from normal subjects and patients with Alzheimer's disease. Samples were digested with HNO in pressure bombs with microwave heat- ing and the digests analysed by ICP-AES and NAA.The main elements Ca Fe IS Mg Na P and S and the trace elements Al B Ba Co Cr Cu Mn Ni Pb Sr and Zn were determined in nine different regions of both hemispheres of the brain. Using pattern recognition techniques a correlation was sug- gested between brain A and Zn concentrations and Alzheimer's disease. Determination of aluminium by ICP-AES is a continuing theme. Recknagel et al. compared different emission lines for the determination of A in pharmaceutical infusion solutions. They found that the emission line at nm had a lower LOD but was subject to interference from high Fe or C concentrations whereas the nm line had interference from high Ca concentrations. The nm line was used with an argon-purged monochromator by Lyon et al. for the measurement of A in serum dialysate fluid and water. Internal standardization with Y was used to overcome matrix effects in serum and dialysate fluid. Results in an external quality assurance scheme showed evidence of good accuracy. However Burden et al. found that interference from Fe limited the use of the nm line and preferred the nm line using dilution of samples with KC to enhance sensitivity achieving an LOD on diluted clinical samples of. pg -' under optimized conditions equivalent to. pg I-' in serum.The effect of KC was first reported by Chappuis et al. Clin. Chim. Acta , who appear to have restated their method in a recent publication. Their method using the nm line and five-fold dilution of serum with KC solution has a quoted LOD in serum of. pmol -' pg -l. A more sensitive approach reported by Hu et al. used ETV with a % m v PTFE slurry as a modifier to help vaporize A as the fluoride.The method was tested on serum bovine liver and mussel tissue RMs and water samples. The latter two solid materials were dry-ashed and the ash slurried with the PTFE. Good agreement was found with indicated and literature values for these RMs. The LOD of the method was. pg. Hydride generation was used by Duan et al. to determine As Sb Se and Sn in biological materials by ICP- AES. Samples were digested with HN,-HClO, taken to near dryness and redissolved in. mol -' HC. Reduction was by % m v NaBH containing.% m v ascorbic acid. The LODs were.,.,. and. pg -' for As Sb Se and Sn respectively. The method was verified by analysis of a hair CRM. Applications of direct-coupled plasma atomic emission spec- trometry are fewer in number but continue to demonstrate the usefulness of this technique. Petersson determined Ca Mg and P in digests of heart and kidney tissue and Ca in aortic tissue and obtained good accuracy on CRMs. Silicon concentrations in serum plasma and urine were determined by Bercowy and Rieders with an LOD of.mg -'. Plasma concentrations ranged from <. to mg -' and urine concentrations from <. to mg -'. Dog urine was analysed for elements by Petersson et al. following wet digestion of samples. As the major elements K Na and P influenced the signals matrix-matching was used to obtain accurate results which were verified by the analysis of SRMs.The application of capacitively coupled MZP-AES to the determination of Pb in whole blood was described by Wensing et al. A p sample of whole blood was deposited on a tungsten electrode in the instrument and then dried at W power by applying microwave energy without any purge gas. In order to ash the sample the power was changed to W and He introduced to form a plasma which ashed the sample. Finally the power was increased to W to vaporize the sample and excite the Pb atoms produced. Calibration was by the method of standard additions.The LOD was pg -l for a p sample and between-batch precision was % RSD. Accuracy was unsatisfactory at concentrations below pg -' but was good at concentrations of and pg -' on blood RMs. Recent applications of microwave-induced plasma detectors with GC include the speciation of organomercury and organotin compounds. Carro-Diaz et al. used a commercial MIP detector with capillary GC for measurement of methylmercury in biological samples. Conditions were opti- mized to resolve the methylmercury peak from interfering C signals. Accuracy was evaluated by the analysis of the CRM R Journal of Analytical Atomic Spectrometry April Vol. DORM- Dogfish Muscle. Organotin compounds were extracted by Suzuki et al. from fish oysters and rat organ homogenates with diethyl ether under acid conditions. Following a two-stage chromatographic procedure the organotins were alkylated with methylmagnesium bromide and separated by GC using a He MIP as detector.The LODs for organotins were in the range.-. pg. Inductively coupled plasma mass spectrometry and other mass spectrometric techniques.There have been several reviews on mass spectrometric methods. A comprehensive review by Aggarwal et al. covers the application of mass spectrometric techniques to the deter- mination of trace elements in biological samples. As the authors are at the forefront of developments in GC-MS for trace element analysis of clinical samples it is not surprising that this review is a particularly good source for developments in this technique. Vanhoe reviewed the capability of ICP-MS for trace and ultratrace element analysis focusing particularly on the multielement determinations carried out by his group. Use of mass spectrometric methods in studying mineral and trace element absorption and metabolism by stable isotope techniques was reviewed by Crews et al. The advantages and disadvantages of the many variants of MS were evaluated. Hill C in a lecture to the SAC conference in Hull UK considered the problems in application of ICP-MS to speciation studies. He considered that the key to success was in the design and development of an interface between GC or HPLC and ICP-MS which allowed both parts of the system to operate under optimal conditions. Although ICP-MS was originally hailed as a multi-element technique it has become obvious in recent years that single element determination of difJicult elements has become very important. In this review year % of the papers on appli- cations relate to single element applications often in speciation studies % are on multi-element determinations and % deal with stable isotope studies. Single element applications are dealt with in section. but it is interesting to note here that the elements As Pb and Pt feature strongly as favourites see alsoTable. An important practical application of ICP-MS is a rapid screenfor toxic elements. Nixon and Moyer C described a method for screening blood urine and sera for As Cd Pb andT. The species Cl was used as an isobaric correction for the ArC interference on As. Results on urine and blood RMs and comparison with ETAAS confirmed the accu- racy of the procedure. Both Vollkopf and Barnes and Hess confirmed the usefulness of ICP-MS for the determination of a range of elements in urine. Measurement of the elements As Cd Co Cu Mn Pb T and Zn took min by ICP-MS compared with min by AAS. A new simultaneous extended dynamic range detector system was shown to be particularly useful in this analysis. In order to obtain accuracy in analysis by ICP-MS care has to be taken to avoid contamination in sample handling and to control interference effects in the determination. Morita et al. found that in the analysis of blood serum disposable stainless steel needles and the exudate from serum separation tubes could seriously contaminate the sample. In their study of matrix interferences from serum and saline solutions Gerotto et al. found that the signal sup- pression in the presence of NaCl depended on the ionization potential and mass of the element. Application of cluster analysis to the data for elements revealed four groups of elements with similar behaviour and for each group a suitable internal standard was chosen. With suitable precautions as detailed above multi-element determinations are perfectly feasible and have been demon- strated in recent studies. In a study to investigate A uptake from some foods by guinea pigs Owen et al. meas- ured Cu and Zn in addition to A in the femur brain and kidney.These elements were also measured in solid and soluble fractions of the intestinal digests and the soluble fraction speciated by SEC-ICP-MS to assess the behaviour of Al Cu Mn Rb Sr and Zn. Narusawa and Matsubara established conditions for the determination of As Ge Mo Ni V and Zn in biological RMs by ICP-MS. Samples were digested by two methods open digestion with HN-HF and pressure digestion in a double-vessel digestion bomb with HNOJ.The latter method offered the advantage of reduced loss of Ge. For all RMs examined except NIES Pepperbush dissolution was complete. For pepperbush heating with HF was necessary to remove siliceous material but Ge was lost in the process.The inorganic composition of rat tissues was determined by Gelinas and Schmit by ICP-MS. Comparison between healthy rats and rats with hypertension revealed differences in both major and trace elements. Shinohara et al. explored the possibility of the use of a microwave induced plasma mass spectrometer for the determination of trace elements in blood plasma and bone digests. They evaluated possible sources of contamination and found the choice of storage containers and reagents important. Interference effects were found which were overcome mainly by the use of Ge or T as an internal standard. With this correction trace elements and lanthanides were found to give satisfactory recovery. Results on two plasma samples for Ca Cr Cu Fe Mg Mn Sr Rb V and Zn were in agreement with those obtained by AAS. Laser ablation offers the possibility of direct solids analysis with high spatial resolution. Durrant and Ward explored its use for the multielement analysis of hair mixed diet and milk powder. Although results were not as accurate or precise as conventional nebulization of acid digests rapid semi-quantitative analysis was possible with little or no sample preparation. In their work on the spatially-resolved analysis of biological tissue Wang et al. evaluated the use of ‘natural’ internal standards such as Ca or Mg to improve the precision. By using an IR laser beam for ablation they could resolve down to pm on samples of fish scales rat kidney cross-sections and pig femur. For ablation of trace metals in walrus and beluga whale teeth Outridge and Evans found that IR lasers were poorly absorbed by apatite crystals the main constituent of tooth material and they used instead lasers giving UV and green light. Of the two UV light was preferable as this gave greater Ca-normalized signals for a range of elements. However results were shown to be wavelength- beam energy- and matrix-dependent. Although dentine and cement from teeth of beluga whales ablated similarly walrus dentine appeared to ablate in a fundamen- tally different way suggesting that matrix effects were species- dependent.Two groups have used stable isotopes of Ni in studies of Ni metabolism in humans C. Interferences par- ticularly from Ca-containing polyatomics were a problem in the determination.Templeton et al. used multivariate calibration with principal components analysis to correct for mass overlaps in serum digests but for urine this was inad- equate and separation of Ca by precipitation as the oxalate was necessary. Patriarca et al. C used solvent extrac- tion with APDC to separate off the Ni.They studied four volunteers who had ingested Ni and collected plasma urine and faeces for d after dosage.The Ni isotopes at masses and were determined by ICP-MS using isotopic dilution with Ni. Templeton et al. first studied rats compar- ing results by ICP-MS with the stable isotope Ni with results by liquid scintillation counting with the radioactive isotope Ni. Good agreement was obtained. The clearance from serum Journal of Analytical Atomic Spectrometry April Vol. R fitted a two-compartment model.The stable isotope approach was then applied to one human volunteer who was found to absorb % of the administered dose subsequently excreted in the urine. The serum Ni level peaked at pg -' at h. For measurement of Mg isotope ratios in biological fluids by TIMS Vieira et al. used -hydroxyquinoline to precipitate Mg from water serum and urine. Although the total Mg recovered by precipitation varied considerably recov- ery was sufficient for isotopic enrichment analysis. Urine samples required prior separation by cation-exchange chroma- tography to remove interferents. In their method for Zn isotope ratios Yokoi et al. digested plasma samples with H and extracted the Zn with diethylammonium diethyldi- thiocarbamate into CCl,.This was then back-extracted into dilute HN and the ratio Zn:Zn measured by ICP-MS. The method was used to establish the plasma Zn disappearance constant on premenopausal women by following the plasma Zn isotope ratio over h after administration of an intravenous dose of Zn. As there is no fixed natural abundance ratio for B Vanderpool et al. found that they could not use isotope dilution calculations on software supplied with their ICP mass spectrometer. For each sample or related data set a natural abundance ratio had to be determined. In order to measure B transport 'OB was fed to a fasted rat. Over the next d % of the dose was recovered in the urine and % in the faeces. Koirtyohann examined ways of improving precision in the measurement of isotope ratios of Cu Fe Li Ni Pb and Zn using the ELAN ICP mass spectrometer. Except for Li the precision of measurement was reduced to.% RSD with measurement times of min. Compensation for a slow drift in apparent isotope ratios with time was achieved by using a third isotope of the test element by a pair of internal standards with isotopes bracketing the mass range of interest or by frequent recalibration using solutions of known is topic ratios. For Li these measures were not so successful and typical precision for the Li Li ratio was around.% RSD. Applications of accelerator mass spectrometry AMS in biomedical research were reviewed by Vogel andTurteltaub. The technique measures isotope concentrations to parts per on milligram-sized samples. Many of the applications relate to C which is outside the remit of this Update but applications to studies of Ca and A using isotope tracers have achieved importance as is evident in the following papers. Day et al. reviewed the application of A as a marker with determination by AMS.The same group of workers studied the distribution of A in the major cell compartments of human neuroblastoma cells finding that A was retained by the nuclear proteins and nuclear sap but did not appear to bind to nucleic acids. The cells were grown in a culture medium containing. mmol -' Al-EDTA spiked with A. The deposition of A in a normal and a uremic rat was studied by Walker et al. Most of the tissue A was found in bone corresponding to.% and.% of the administered dose in the normal and uremic rat respectively. Besides bone A was found in the other tissues in the order kidney >liver > heart > brain and muscle. In their studies on rats Jouhanneau et al. found that the intestinal A absorption as measured with a A tracer was even lower about.% and not significantly enhanced by the presence of citrate. Only about.% was retained by bone. Further rat studies were made by Fink et al. but focused only on liver and brain concentrations. Studies on two human volunteers administered A were reported by Hohl et al. Serum and urine A concentrations were measured by AMS over d.The data could be described by a four- compartment model involving resorption elimination and exchange between the compartments. Calcium resorption from bone in humans was studied by Johnson et al. using an injected dose of 'Ca and measurements by AMS of Ca in serum and urine collected over d.The Ca:Ca ratio rapidly decreased after injection reaching a steady state after about d. In an attempt to understand Ca uptake and deposition in heart tissue during ischaemia and reperfusion Southon et ql. developed methods using isolated rabbit hearts with "Ca as a tracer. Aggarwal and co-workers have extended their work on applications of GC-MS to the determination of trace elements with stable isotope dilution methods for the determination of Pb in urine and blood and Te in urine. The use of lithium bistrifluoroethy dithiocarbamate as a chelating agent in the determination of Pb in urine showed a strong memory effect which was overcome by further derivatizing the complex with -fluorophenylmagnesium bromide. The same two-stage process was used in the determination ofTe. Lead was enriched with 'Pb and Te with "'Te. The Pb method was validated by analysis of NIST Urine SRMs urine and blood RMs from the New York Department of Health and survey blood samples from the College of American Pathologists. The method for Te was used to deter- mine urinary Te concentrations in the range - pg -l from patients treated with a Te-containing antitumour drug and validated by comparison with results by ETAAS. X-ray fluorescence spectrometry Interest in in-uiuo measurement by XRF remains high. Using a Tc source Todd et al. measured Pb and Pt in the kidneys of patients treated with cisplatin in order to test the hypothesis that the treatment mobilizes skeletal Pb. The majority of patients had unmeasurable Pb levels; determination of blood and urine Pb by other techniques confirmed that Pb handling was little different from normal.The possibility of incorporating the X-ray source Tc in a bone-seeking pharma- ceutical was explored by Mountford et al. for the measurement of Pb in tibia. As the internal source corresponds to a much greater dose than an external source these workers concluded that for the measurement to be practical with a safe dose the sensitivity would have to be increased from that found - pg g-' LOD. Cadmium in kidney and Pb in finger bone tibia and calcane were measured by Nilsson and Skerfving. Levels of Cd in the kidneys of persons not occupationally exposed to Cd could also be satisfactorily measured. Zaichick described in uiuo techniques by INAA and XRF including the determination by XRF of Ca Pb Sr and Zn in teeth with a 'Cs source. In a conference presentation C Adams and Janssens outlined the impact of new third-generation synchro- tron sources in synchrotron radiation induced X-ray microanal- ysis. One of these the European Synchrotron Radiation Facility ESRF in Grmoble France had been opened and was operating.The brilliance and energy of the X-ray source would allow the analysis of trace elements in.-. pm particles and visualization of the distribution of trace elements in thin biological and geological samples with good lateral resolution. The use of SR for trace element analysis of clinical and biological samples was reviewed by Valkovic and Moschini. To investigate lead accumulation in diflerent cell organelles such as renal tubuli and in osteoclasts Barckhaus et al. used EPMA and LMMS.The former technique allowed the analysis of Pb in volumes less than. pm. Lead inclusions were found to be often accompanied by the element selenium. There have been few recent applications of total rejection XRF. Von Bohlen et al. examined elements in dental plaque by TXRF. No chemical pretreatment was neces- sary. Near amalgam fillings Hg concentrations in plaque R Journal of Analytical Atomic Spectrometry April. reached levels as high as mgkg-l. In a study of the mechanism of acute As toxicity Nakai et al. used TXRF to determine As in mouse tissues. The tissues were digested with HN and As measured in the presence of Sr as an internal standard. Arsenic was found in the highest concentration in the liver with moderate levels in lung and kidney and the lowest concentration in the brain.The use of dual-energy X-ray absorptiometry for measuring bone mineral content BMC and bone mineral density BMD was adapted for small animals by Casez et al. In rats accuracy was assessed after measurement by sacrificing the rats recovering the skeleton dissolving the bones in HCl and determining Ca by FAAS. Assuming the bone was all hydroxyapatite the bone Ca concentration could be derived from the BMC. Total body Ca calculated by these two ways were highly correlated leading to the conclusion that dual X-ray absorptiometry provided a precise and reasonably accu- rate way of estimating skeletal Ca content in the rat. A similar study carried out by Louis et al. evaluated the accuracy of the technique for measurement of the mineral content of vertical trabecular bone taken from cadavers. After measurement the bone was powdered and mineral content determined by NAA and FAAS. Results by all methods correlated well all correlation coefficients being >.The release of metals from stainless steel implants in bone was studied by Mariolani et al. using XRF. As a model stainless steel plugs coated with and without A TiO and Nb were inserted into canine femurs and followed at periods of up to weeks using radiography and XRF. Release of elements from the materials into the bone was found. Shenberg et al. used XRF to study the accumulation of trace elements in kidneys of tumour-bearing mice after treatment with a Pt-containing drug. The elements Cu Fe K and Zn increased in the kidneys to a maximum after d but the accumulation of Cu Fe K and Pt were significantly reduced by giving selenite with the drug. Other multi-element techniques and studies.There have been few reports on multi-element atomic absorption spectrometry this review year. Smith et al. evaluated a linear photodiode array as a detector for continuum source AAS with electrothermal atomization. The LODs obtained were similar to those obtained with a photomultiplier detector and wavelength modulation. Integration of the absorbance signals across the line profile however allowed a greater linear range to be attained. The elements Cd Cr Cu Mn Mo and Pb were determined in a range of NIST environmental and biological SRMs with results in agreement with certified values. Continuum source ETAAS was also used by Sanford et a!. C to determine Pb in whole blood after digestion with HNO,.There have been important commercial developments in simultaneous ETAAS see J. Anal. At. Spectrom. R and but as yet no reports of applications to clinical and biological samples have appeared; these are awaited with interest. A new commercial multi-channel spectrometer allowing simul- taneous determination by AFS of hydride-forming elements was described by Wang and Grillo C. Modulated high intensity HCLs were used as light sources with non- dispersive optics and photomultiplier detectors. An FI system was built in to handle hydride generation. Eleven elements As Bi Cd Ge Hg Pb Sb Se SnTe and Zn were claimed to be determinable with this instrument. Elemental analysis of prehistoric bones can give information on past environmental conditions and diets. Kniewald et al. determined Ba Ca Cd Cu Pb Sr and Zn in fossilized human bone by ICP-AES and differential pulse anodic stripping voltammetry ASV. Strontium concen- trations were found to be markedly different from those in bones today. Concentrations of elements in bones can however change when covered in soil. Ways of estimating the original concentrations were developed byTaufer and Tauferova. Copper Mn and Sr concentration profiles across a cross-section of a mammoth's bone were determined by AAS. From the data a suitable exponential or diffusion function could be derived from which the original trace element concen- trations could be calculated. Reliable data on concentrations of trace elements in healthy subjects is important for all studies. Ojo et al. reported concentrations for elements in whole blood plasma and erythrocytes of Nigerian subjects. Analysis was by INAA PIXE and ETAAS. Results were generally in agreement with ranges reported for other parts of the world. In a separate study from Nigeria Omokhodion and Howard measured Al Cd Cu Mn Ni and Zn in the sweat of healthy subjects by AAS. Mean sweat concentrations varied from. pg -' for Cd to pg I-' for Cu indicating that in hot countries sweating could be an important excretory route for trace elements. A study from Greece established normal values of Al Cu Mg Mn Pb and Zn in serum and CSF by FAAS and ETAAS. Values for Cu Fe Mn and Zn in breast milk of French women were obtained by Arnaud and Favier by ETAAS and FAAS for Zn. Iron Mn and Zn concentrations declined with time from maxima at days and post-parturition respectively whereas Cu concentrations remained constant.Transfer of toxic elements from mother to infant can be significant. Concentrations of Cd total Hg methylmercury and Pb in maternal and umbilical cord blood were determined by Ong et al. using ETAAS.The essential elements Cu and Zn were measured by ion chromatography. Methylmercury and total Hg concentrations were higher in cord blood then maternal blood whereas Cu Pb and Zn concentrations were lower. Cadmium concentrations were similar. For a polluted industrial area of Poland Baranowska et al. found higher concentrations of heavy metals in placental tissue than in samples from a less polluted region. Samples were pressure digested with HN and concentrations of Cd Co Cr Cu Mn Mo Pb and Zn measured by ETAAS.There have been some interesting studies in dentistry. The release of metal cations from dental casting alloys was studied by Tasaka et al. in model experiments. Silver and Pd were relatively resistant to corrosion by human saliva but Cu was significantly corroded. Corrosion of Zn was less as the surface became coated with a white material which slowed down further corrosion. Measurements were by ICP-AES. Tanaka et al. measured the concentrations of Al Mn Pb and Sr in healthy teeth and in teeth with caries by FAAS and ETAAS. The concentrations of these four elements increased in both enamel and dentine with the severity of caries. To assess the exposure of dental technicians to Cd Cr and Ni Min et al. measured air levels and whole blood concentrations by ETAAS and compared the results with those taken in offices. Only blood Ni concentrations were significantly higher in the dental technicians than in the office workers.The Ni concentrations were related to the length of employment as a dental technician. The group of Granadillo and Romero have been carrying out studies on Al Cu Fe Pb Vand Z n in clinical samples by ETAAS. Diluents used were.% Triton X- for whole blood plasma or red cells,.% Triton X- with. mol - HNO for urine and. mol -' HNO for digested samples e.g. bone. For Pb and V a chemical modifier based on Pd and citric acid was also used. Accuracy was verified by analysis of a range of clinical and environmental CRMs. The methods were used in a study of these elements in arterial hypertension and in renal dialysis C Journal of Analytical Atomic Spectrometry April Vol. R . Higher levels of blood Pb and plasma A furnace. Programme times were - s which although faster were associated with arterial hypertension in subjects without than normal are not as fast as they could be. Wang and renal disease. Vanadium appeared to have no role in Demsbar developed a programme with a time of s hypertension. Studies of As Cu Fe Se and Zn in the blood of patients suffering from blackfoot disease a form of gangrene of the extremities showed changes through five clinical stages. Wang et al. digested the blood samples and then measured the trace elements by FAAS or HGAAS. Copper concentrations were unchanged throughout progression of the disease whereas As increased in the first three stages and then decreased. Arsenic toxicity was believed to be the cause of the disease but the later decrease in blood As concentrations was thought to result from the antagonistic effect of selenium. See also section. for hair results from the same study. Changes in essential elements in disease have featured in a number of studies. Rohn et al. found that Mg levels in plasma and leukocytes were significantly lower in diabetic children than in healthy children.They measured Cu Mg and Zn in plasma blood and cellular components by Zeeman- effect FAAS. Differences in Cu and Zn were not significant. In children with severe asthma Malvy et al. found significantly lower plasma Se red cell glutathione peroxidase and plasma Zn and higher plasma Cu and Mn concentrations than in healthy controls. Measurements of trace elements were by FAAS and ETAAS. Yang and Xu measured Cu Fe and Zn in erythrocyte membranes by FAAS for healthy subjects and patients with lung cancer. In the patient group Fe was significantly higher whereas Zn was lower. Results were expressed as a ratio to the mass of membrane protein. Developments in Single ElementTechniques.The need for screening large numbers of children in the USA for their blood Pb concentration has prompted the develop- ment of rapid simple and low-cost dedicated analysers some of which were described at the Pittcon conference. The portable detector developed by Jones et al. C used a W-coil atomizer powered by a V car battery a normal hollow-cathode lamp source and a fibre optic cable transmit- ting light to a small CCD spectrometer mounted on a PC card in a portable computer. Background correction was made by using a non-absorbing Pb line at.nm close to the analytical line at. nm.The W-coil could withstand atomization cycles. The LOD of the system was pg -l for a pl sample injection. Parsons et al. C also used a W-coil atomizer but used the Smith-Heiftje effect for back- ground correction. A photomultiplier detector was connected to a personal computer for evaluation of signals. At the stage of development reported the formation of carbonaceous resi- dues from the blood matrix was a problem. The. Thermo Jarrell-Ash Corporation have produced a dedicated graphite furnace workstation for routine blood Pb measurement C. Samples were diluted -fold in a modifier contain- ing HN NHH,P and Triton X- and calibration solutions were prepared from a concentrated solution directly by the autosampler. Sample cycle time was s allowing about samples per hour to be analysed. Developments in fast furnace methods in ETAAS were reviewed by Halls.The principles were applied by Granadillo et al. to develop methods for the determi- nation of Cr in whole blood serum urine and bone digests. As pyrolysis could be carried out at °C without loss of Cr background absorbance was minimal and correction was not required. No chemical modifier was necessary and wall atomization from a pyrolytic graphite coated graphite tube was preferable. Good results were obtained on CRMs with both an older instrument with a conventional furnace and a modern Zeeman instrument with a tranverse-heated graphite for the determination of Cu in serum and urine. Serum samples were diluted + and urines + with.% HNO,,. %Triton X- and lop injected onto a L'vov platform in a pyrolytic graphite coated graphite tube. Times in the drying and ashing stages were minimized. No real difference in precision was seen between the fast programme and a more conventional programme; the performance of the method in an external quality assessment scheme proved excellent accu- racy in routine use. One of the problems that become apparent as programme times get shorter is the length of time it takes for the autosampler to inject samples. Halls developed a device to allow the autosampler to begin its action at a pre- set time before the end of the heating programme. An overlap time of s was found to be suitable. The device was evaluated in routine use with and without the overlap time for the determination of Pb in blood.There was no significant differ- ence in results the device allowing a time reduction of s per injection. Information is now appearing in publications from users about the performance of the commercial transverse heated graphite atomizer THGA. Bozsai and Melegh found that LODs for Ag Co Cr and Ni in water were.,.,. and. pg l-' respectively significantly better than with a conventional furnace. Interestingly Granadillo et al. found an LOD for Cr of. pg l-' which was not as good as that obtained with a conventional furnace in an instrument with D,-arc background correction. pg -l. The former workers found that the THGA eliminated inter- ferences from C- and SO- in the determination of Ag in water. They were able to determine Cr and Ni in urine at the pg I-' level. Zeeman background correction was originally thought to overcome all the disadvantages of D,-arc background correc- tion including overcorrection. More recently examples have appeared in the literature in which overcorrection occurs with a Zeeman system. Zong et al. C found overcorrection in the determination of Pb in bone digests at. nm when phosphate was used as a modifier. It was present when an instrument with the latest longitudinal Zeeman background correction was used Perkin-Elmer ZL but not present with the older with a transverse Zeeman system.They concluded that the interference was produced from PO formed from in the presence of Ca or Mg and suggested that the PO molecular absorption bands are split in the magnetic field. There have been some interesting interfaces developed for atomic absorption detectors coupled to HPLC separation. Chang and Robinson constructed a thermospray to take column eluate desolvate it and deliver it as a particle spray into a flame. Pre-heating of the interface for at least min was necessary to obtain reproducible results.The system was applied to the speciation of Cd compounds in urine and sweat. A silica T-tube atomizer was developed by Momplaisir et al. for the detection of As and Se compounds in the eluate of an HPLC column. Silica T-tubes are generally used with hydride generation but in this interface the eluate is introduced through a thermospray into a H,- flame in the vertical part of the T. It was suitable for both aqueous and polar organic mobile phases and provided almost equivalent response for different compounds of As and Se. Speciation of As in the Dogfish Muscle RM DORM- was successfully accomplished. A tungsten tube atomizer can give a -fold improvement in LOD over a graphite atomizer for the determination of A in biological materials its Ohta et al. showed. Hydrogen R Journal of Analytical Atomic Spectrometry April. was added to the Ar sheath gas and under optimal conditions the LOD was ng -'. A -fold improvement in the sensitivity of determination of Ag by FAAS was obtained by using atom trapping for min.The method was tested on a digest of Oyster Tissue RM. The precision of the measurement at. pg g-' was.% RSD. Laser-excited atomicjuorescence with an isothermal graphite atomizer allowed Enger et al. to determine Sb down to ng -l levels. Simultaneous detection over a wavelength region with an intensified charge coupled device permitted the correction of background signals. Whole blood samples from normal individuals diluted -fold with ultrapure H,O had concentrations ranging from below the LOD ng -' to ng -'. Precautions had to be taken in sampling as contamination was found to be an important factor. A novel way of determining K and Nu within individual human erythrocytes was described by Cheung and Yeung. By firing a laser pulse at the cell the material was vaporized and the K and Na atomic emission was monitored. Amounts of Na as low as fg could be detected. Intracellular K and Na contents varied by & % and & % respectively and there was only a weak correlation between the two element contents in single cells. In the electrothermal atomizer constructed by Kitagawa et al. a cm long vertical glassy carbon tube was packed over part of its length with activated charcoal and heated to a constant temperature of °C by a power supply of about kW. Samples were inserted into a graphite cup which was mechanically lowered into the hot tube.The sample vapour passed through the activated charcoal column and into the spectrometer light path below. Background absorbance was minimal but sensitivity was low e.g.,. ng for Cu and a matrix effect was found. When direct calibration was used in the determination of Cu in slurried NIST Bovine Liver SRM a result of pg g-' was obtained below the certified range of & pg g-'. Reference Materials and Quality AssessmentTaylor et al. described the performance of labora- tories in an external quality assessment scheme for the determi- nation of A in dialysate fluids and water. Whereas most laboratories could determine A reasonably well in serum more problems were encountered in the analysis of water and dialysate fluids for which the between-laboratory coefficients of variation were about - to -fold higher than for serum.The scheme involved the analysis of two dialysate fluid and two water samples per month. Each participant received a report giving the mean standard deviation and coefficient of variation of results after exclusion of outliers and the amount of A added to the sample. Despite the wide range of results the mean values were close to the anticipated concentrations. Over the period - the between laboratory coefficients of variation fell from about to % and from to about % for dialysate fluids and waters respectively.The results of an interlaboratory comparison of the analysis of a range of plant and animal materials by solid-sampling ETAAS were reported by Herber and Grobecker. Eleven laboratories analysed red cabbage two bovine liver materials milk powder kale industry dust and fish homogen- ate for Cd Cu Hg and Pb. Results were generally satisfactory except for the determination of Cu in bovine liver and Cd and Cu in industry dust. Hair and Nail Analysis. There has been some interesting work recently on the distri- bution of metals in hair. Watanabe et al. examined cross-sections of hair by SEM to identify the melanin granule. Analysis by ICP-AES showed that some metals existed more abundantly in refined melanin granules than in the whole hair. Black hair contained about twice the concentration that was present in white hair but bleaching agents and permanent wave lotions caused very little extraction of metals from the hair. Formic acid however completely extracted Ca and Mg from hair. Surface contamination was studied by Cargnello et al. using both SEM and micro-PIXE.They concluded that persisting extraneous matter on hair was a likely source of inconsistency with bulk analysis even after washing. Five washing procedures were examined which all reduced the contamination but did not eliminate it. They therefore used high resolution micro-PIXE beam diameter pm to measure the elemental concentration in a cross- section differentiating the core concentration from the surface contamination.Three types of radial distribution were observed a uniform distribution e.g. S P a parabolic distribution Ca K Zn and a uniform distribution with high peripheral concentrations Fe. Distribution along the length of the hair was studied by Wu et al. using SRXRF. They found that the trend of concentration change was basi- cally the same in three different hairs from the same area of one subject but very different from the hair of a different person. Some good examples of the value of examination of the distribution along the hair were given by Yoshinaga et al. The hair was cut into sections a few mm long which were individually dissolved in small volumes of HNO and the elements determined by FI-ICP-MS. Hair from a Russian scientist visiting Japan showed a low Hg concentration at the distal end which corresponded to his life in Russia when his fish consumption was minimal.The much higher concentration at the follicle end corresponded to his more recent life in Japan where he ate fish often. Hair samples from a patient poisoned by T similarly reflected his exposure history. Can hair analysis be useful in the diagnosis of disease?. The most obvious and useful applications are in the assessment of exposure to toxic elements as for example in the TI-poisoned patient above. Wang X. et al. concluded that hair analysis could be used as a preliminary clinical diagnosis method for cancer. They measured a range of elements in the hair and serum of cancer sufferers and controls by ICP-AES separately measuring Se by ETAAS. Chemometrics partial least squares and Gram-Schmid methods were used to classify the results. For patients with blackfoot disease Wang C.T. et al. measured hair As Cu Fe Se and Zn concentrations at five different clinical stages using FAAS. Copper and Zn changed little but Se and Fe decreased as the disease progressed. Arsenic increased in the first two stages and then decreased.The effect of arsenic was thought to be responsible for the decrease in hair selenium. Can hair analysis be used as an assessment of nutritional status? Contiero and Folin studied Cu and Zn levels in hair of young people aged.-. years. The correlation of hair concentrations measured by AAS and XRF with dietary intake of Cu and Zn was examined. The authors concluded that hair Zn may be a useful additional assessment of groups of individuals. However there is much recent evi- dence that indicates that hair Zn does not indicate body Zn stores particularly the definitive work of CortesTor et al. J. Radioanal. Nucl. Chem. featured in last year's Update. An element for which hair analysis has some meaning is selenium which links like S to keratin. The strong bonds are difficult to break requiring aggressive digestion procedures. Harrison et al. used a micro- wave digestion procedure based on heating hair with HNO for min and then adding H for further reheating for min. For nails longer heating with H was necessary. Final determination was by ETAAS with Pd as a modifier giving an LOD of. pg g-'. Accuracy was confirmed by analysis Journal of Analytical Atomic Spectrometry April Vol. I R of CRMs and by comparison of results with those by NAA. Results for samples from normal subjects gave a mean ~ t s of.k. pg -l for hair and.k. pg -l for nails.There was a good correlation r =. between hair and nail Se concentrations from individuals. Hair Se concentrations in heifers were measured by Martinez et al. using HGAAS. Hair samples from heifers from the Valley of Mexico which had died from sudden heart failure had concentrations less than. pg g-' compared with healthy heifers at sea level which had a mean concentration of. pg g-'. Hair and nail arsenic can be a useful indicator of body arsenic burden. Studies on 'the biggest arsenic calamity in the world' were reported by Das et al. Six districts in West Bengal India had drinking water contaminated geologi- cally with As. Symptoms of As toxicity were common in the people of these areas. Hair and nail arsenic analysis was used in the study of affected people. Samples were dissolved in HN by pressure digestion and As determined by FI-HGAAS. In the Czech Republic concern about the effect of As released from the combustion of brown coal led Kombercova et al. C to examine hair As in patients with types of skin disease and in controls. However results obtained by HGAAS did not suggest any relationship of disease to As exposure. Koons and Peters examined the distribution of As along the length of individual human Analysis of ephedrine samples by ICP-MS showed that six elements Al Ba Mn Pt Rb and Sr were useful to assess the difference between samples of various origins.The platinum species present in a new antitumour drug formulation based on cisplatin were separated by HPLC and detected on-line by ICP-MS in a study reported by Hill et al. C.The interface consisted of a pneumatic nebulizer to spray eluent acetonitrile-water into a heated spray chamber. Further desolvation was achieved by a membrane drier tube in series with a Peltier-cooled cryogenic condenser. Methods for the determination of trace elements in Chinese traditional medicines continue to be developed. Huang et al. measured As by ETAAS with a Ni modifier after heating the drug with concentrated HS-NH ,S-KS for h and making up to volume with H. Full recovery of realgar AsS was possible with this approach. Hydride-generation AAS was used by Li et al. to determine As and Sb after digestion of samples with HN-HC-H,S. The method was used for quality control in the production of a Chinese medicine.Tian et al. described the determination of Cd Cr and Pb in two traditional medicines by ETAAS. The samples were dry- ashed at °C and then dissolved in % v v HNO prior to dilution to volume. hairs by solid-sampling ETAAS. Hair lengths of mm were directly inserted into a cup-in-tube solid sampling device. Marine and Freshwater Biology together with Pd and MgN as modifier. Simple aqueous standards were adequate for calibration. Comparison of results with data obtained by NAA confirmed the accuracy of the procedure. Cadmium and lead concentrations in the hair of school- children in rural and industrial areas of southern Poland were measured by Chlopicka et al. using ETAAS with Zeeman background correction. Mean concentrations found were. k. and. f. pg -l for Cd and Pb respect- ively. Boys tended to have higher concentrations than girls living in the same area. Indium was determined in hair by Cai et al. who used a graphite probe to introduce solutions into a constant temperature furnace in ETAAS. Samples were first dry-ashed and the ash dissolved in dilute HCl. Analysis of samples from normal subjects gave a range of -ng g-'.The LOD was. pg. According to MacPherson et al. hair calcium is inversely related to the concentration in the aorta and about % of people who have a myocardial infarction have low hair calcium concentrations. A preliminary study of one indi- vidual showed a marked response in beard calcium to vitamin D supplementation and as a result of a holiday in a sunny region. In a larger study attempts at improving Ca status of volunteers by supplementation with vitamin D or antioxidants or both did not show a significant increase in beard calcium but plasma Ca was lowered. Supplementation improved Se status. Prior to supplementation % had plasma Se lower than pg I-'; after supplementation this was reduced to %. Beard Ca was measured by XRF and hair Ca by ICP-AES after digestion of the samples. Drugs and PharmaceuticalsTrace element profiles of illicit drugs can be used to trace the source of supply. Wolnik et al. applied ICP-AES and ICP-MS to determining metallic impurities in sodium gammahydroxybutyrate GHB and ephedrine hydrochloride ephedrine. Analysis of over samples of GHB by ICP- AES allowed the detection and determination of Ba Ca Cd Fe K Mg Ni P Pb Si Sr and Zn. The data were used to provide information for investigators tracing sources of supply.There have been developments in simplifying sample prep- aration for the speciation of organotins in fish. Ceulemans et al. developed procedures using solubilization with tetra- methylammonium hydroxide TMAH or enzymic hydrolysis. Solubilization with TMAH was also used by Kuballa et al. Both groups of workers used in situ derivatization with NaBC,H , separating the ethylated butyltins by GC and detecting by MIP-AES or AAS. The study of Kuballa et al. was directed at Hamburg harbour Germany which contained high levels of tributyltin from anti-fouling paints and at a tributary of the Elbe the Mulde into which effluent from a factory producing organotins was discharged. High levels of tributyltin up to pg g-' in wet liver tissue were found in the fish. Although tetrabutyltin was clearly found in the water it could not be found in all the fish tissues. Vela and Caruso C explored the use of supercritical fluid extraction as a sample extraction step fol- lowed by HPLC and ICP-mass spectrometric detection using an RM as a test substance for developing the method. For speciating mercury in dolphin liver Palmisano et al. used LC with on-line CVAAS. Protein-bound Hg was released from a homogenate of the liver by acid hydrolysis iznd inorganic methyl- and ethylmercury separated as cystein- ato complexes on a reversed-phase column with isocratic elution.The LODs were around ng -l. The only clean- up step used was simple centrifugation. Selective reduction with SnC and SnCl,-Cd in CVAAS was used by Gutierrez et al. to distinguish inorganic and methylmercury. Samples were digested with a solution of NaOH NaCl and cysteine either at °C for h or overnight at -°C.The two approaches gave equivalent results. In order to study the changes in bound andfree metal ions during the processing of shellfish-basedfoods Chou et al. speciated Ag Cd Cu and Zn by gel chromatography on Sephadex G- or G- columns followed by off-line detection by AAS and polarography. Lobster digestion gland extracts were prepared with and without a-toluenesulfonyl fluoride a protease inhibitor. Cadmium and Zn were found to be rapidly released from their bound forms in the absence of the protease inhibitor. Speciation of arsenic in marine biological materials continues to attract interest. In an evaluation of extraction methods R Journal of Analytical Atomic Spectrometry April Vol. workers at the University of Barcelona opti- mized extraction with methanol-CHC methanol and methanol-H,O. Methanol-H,O was considered to be the best. Samples were then separated by LC on an anion-exchange column.The As species separated by gradient elution with phosphate buffer were mixed with KS and irradiated with UV light to break down organic forms to inorganic As. Following this ASH was generated by reduction with NaBH and measured by ICP-AES. The main species found was arsenobetaine. Le et al. speciated As in marine algae bivalves and crustaceans by two techniques HPLC with detection by ICP-MS and HGAAS after micro- wave digestion. Arsenosugars were the major As compounds found in marine algae whereas arsenobetaine was the domi- nant species present in crabs and shrimps. In bivalves arseno- sugars and arsenobetaine were both present in significant amounts. Headspace GC was used by Ballin et al. to speciate As in marine fish.Total As was determined after wet digestion and HGAAS. For determination of arsenob- etaine the sample was extracted with aqueous methanol a portion of the extract hydrolysed by heating with NaOH and the headspace gas analysed by GC with flame ionization or AAS detection. On average the arsenobetaine was % of the total As content. Heavy metals inJish from Laguna de Bay in the Philippines were determined by Madamba and Pamulaklakin using AAS. The mean Cd levels in whole fish were. pg g-' but Cd was not detected in the edible portions. Lead was not detected in all samples. Copper and Zn concentrations were. and. pg g-' respectively. Concentrations of elements in mussels from the waters of southern Lake Ontario USA were determined by Mills et al. using ICP- AES after dry ashing the samples and dissolving the ash in HC. Mercury and Se were determined by CVAAS and molecu- lar fluorescence respectively. Chakraborty et al. advo- cated the use of BiNO as a chemical modifier for the determination of Pb in fish tissues by ETAAS. A better LOD and lower atomization temperature than with Pd as modifier were possible. A microwave digestion method for the determi- nation of As Cd and Pb in seafood products by ICP-AES and ICP-MS was developed by Sheppard et al. Homogenized seafood was treated with HNO and allowed to pre-digest for min after which a six-stage pressure-tempera- ture programme was applied.The LODs reached were.,. and.- g-' by ICP-AES and. and.ng g-' by ICP-MS for As Cd and Pb respectively. Progress for Individual Elements. AluminiumThis review period has seen the continued publication of large numbers of papers on the determination of A in biological materials particularly for medical applications. Whereas most trace element laboratories were able to determine A in serum accurately Taylor and colleagues found that many did not perform as well in an external quality assurance programme for the determination of A in dialysate fluids and water. Over a seven-year period between-laboratory RSDs for dialysate fluid A concentrations below. pmol -' fell from to %. A better improvement from to % was seen for the simpler water matrix. Few laboratories however reported consistently accurate results.The authors considered that laboratories did not always pay sufficient attention to interference effects from these particular matrices. Several studies have investigated matrix interferences and the use ofdiflerent chemical modifiers in the determination of A in biological samples by FAAS ETAAS and ICP-OES. Tang et al. examined the influence of different acid matrices on the determination of A by ETAAS with STPF conditions. No interference on the integrated absorbance signal was found for any acid studied. The effectiveness of NH,HP and of nitrates of Ca Mg and Pd as chemical modifiers was also examined. All modifiers stabilized A up to pyrolysis tempera- tures of °C. Both CaNO and PdN produced a sharper atomization peak whereas Mg NO gave multiple atomization peaks. Calcium nitrate and HNO was rec- ommended as the most suitable modifier for samples containing high Ca and C concentrations. Chemical modification with MgNO was found by Winnefeld et al. to be satisfactory for the determination of A in serum by ETAAS. Serum samples were diluted + v v with a solution containing.% MgN ,,.% HNO and.%Triton X-. The influence of sample matrix and inorganic ions on the determi- nation of A in urine by ETAAS was examined in detail by Darmati and Veselinovic. Enhancement of the absorp- tion signal was observed with NH,H,PO, MgCl and CaCO, whilst the absorption signal was suppressed by HCl. Errors of determination exceeded % for urine A concentrations of < pg -'. The authors considered only standard additions calibration to be satisfactory for the accurate quantification of A in urine by this technique. Standard additions calibration was also found by Lai and Yao to be necessary for the accurate determination of A in urine by FAES following sample digestion with HNO and H. In the method described by Aceto et al. for the determination of A by AAS A was pre-concentrated from strong saline matrices by complexation with. mol -'Tiron ,-dihydroxy- ,-benzenedisulfonic acid and adsorp- tion on AG-MP anion exchange resin. Bound Al"' was eluted with. mol - HCl either off-line for determination by ETAAS or on-line for FAAS. The LOD for determination by ETAAS was ng - and recovery was better than %. The method was used to determine A in dialysis fluids. An extrac- tion procedure was also developed by Martin-Esteban et al. for the determination of A in dialysate fluid and tap water by FAAS and ICP-MS.This group used Chromotrope B immobilized on AGl-X anion exchange resin to remove A from the sample matrix with subsequent on-line determination. Limits of detection with an optimum flow rate of ml min-' for A preconcentration were and. pg -' for FAAS and ICP-MS respectively. The efficiency of various sorbents for the preconcentration of A from dialys- ate solutions for determination by FAAS was investigated by Jancarova et al. A -fold enrichment was obtained using columns packed with silica gel or Chrome Azurol S modified Amberlite IRA resin. Interference from albumin was minimized by adding. YO Triton X-,.% polyvinyl- pyrrolidone and.% trypsin to the sample diluent. An interference from Fe"' was also observed with the modified Amberlite resin. Ohta et al. reported a ten-fold improvement in sensitivity in the determination of A in biological samples by ETAAS using a W-tube atomizer and mixed Ar-H purge gas. With optimized gas flow rates of ml min-' Ar and ml min-' H, a characteristic mass of. pg and an LOD of. pg I-' were obtained.The performance of longitudinally heated and transversely heated atomizers was compared by Bradley and Leung for the determination of A in plasma and urine by ETAAS. Regression analysis r =. showed that the two systems gave comparable results. However analyte carryover was significantly reduced with the transversely heated atomizer. The transversely heated system also allowed a faster temperature programme and lower atom- ization temperature thereby markedly improving both tube lifetime and sample throughput important concerns for the busy clinical laboratory.The optimal experimental conditions for the accurate deter- mination of A in biological materials by ICP-OES were Journal of Analytical Atomic Spectrometry April Vol. R comprehensively examined by Burden et al. The emission line at nm was the most suitable for a wide variety of matrices but required background correction for interferences from Ca. The most important parameters affecting analytical sensitivity and precision were considered to be sheath gas flow plasma window size and sample diluent. With these parameters optimized a detection limit of. pg -I in diluted clinical samples was achieved. A critical examination of different emission lines for the determination of A in dialysate solutions by ICP-OES was also made by Recknagel et al. Only two emission lines and nm gave an LOD below pg l-' which was necessary for this appli- cation. Interferences from high concentrations of C and Fe were observed at the nm emission line.The nin A emission line was selected by Poupon et al. for the determination of A in human serum. Serum was diluted + v v with g -' KC which reduced the interference from Ca. A detection limit of. pmol -' and precisions RSDs of. and.% for. pmol-I of A and. pmol -l of Al respectively were reported. Lyon and colleagues on the other hand selected the nm emission line to determine A in serum water and dialysate fluid Matrix interference effects were overcome by using a Y internal standard and careful selection of the wavelength chosen for background correction.The method gave highly satisfactory results in an external quality assessment scheme for serum and water. Use of a Y internal standard was also the approach taken by Brunk to correct for matrix effects in the determi- nation of A in serum by ICP-MS. To achieve better analytical sensitivity or perform speciation studies three groups described coupled techniques for the determination of A in biological materials. Bin et al. and used ETV-ICP-OES to determine A in human serum NIST bovine liver and BCR mussel tissue CRMs. Samples were introduced into the atomizer as aqueous slurries with % m v PTFE as chemical modifier. Addition of PTFE as a fluorinating agent improved the LOD to. pg -' from pg - '.A metal-free HPLC-ETAAS technique was developed by Van Landerghem et al. to study protein binding of A and Fe. Interferences from salts in the HPLC gradient elution buffers on the ETAAS determination of A and Fe were overcome by chemical modifiers.The method was used to study the competition between physiological concentrations of A and Fe for serum proteins. A sensitive ion-exchange HPLC- ETAAS technique was also developed by Wrobel et al. to study the speciation of A and Si in human serum. Confirmation of A binding proteins was determined by gel electrophoresis of HPLC column fractions containing Al. Results confirmed previous findings that transferrin was the only serum protein that bound Al and % of total seruni A was bound to this protein. The remaining serum A was identified as an LMW Al-citrate complex.The group also observed that A was partially displaced from transferrin by desferrioxamine DFO to form an A-DFO complex. How- ever they found no evidence of A-Si interaction to suggest significant aluminosilicate formation in human serum. There has been much work published on the use of A and its measurement by accelerator MS AMS to study the metabolism and intracellular distribution of Al. Although the technique is extremely sensitive there are few facilities where such studies can be undertaken. A detailed review of the technique and its application to studies of A distribution in biological systems was made by Day et al. The technique was used by this group to study the sites of A binding in human neuroblastoma cells. While A was determined in the nuclear fraction it did not appear to be bound to nucleic acids. Jouhanneau et al. used the technique to study gastrointestinal absorption of A in rats.They determined that under physiological conditions gastro- intestinal absorption of A was.% which was more than two orders of magnitude less than that previously estimated for a single human subject using the same technique. Absorption was not enhanced by citrate. Hohl et al. adminstered A to two human volunteers and measured concentrations of the isotope in serum and urine over a d period. The experimental data were described by an open four- compartment model. Rate constants for A re-sorption and elimination were determined. Fink et al. reported preliminary data from studies of A uptake and retention in rat tissues following oral administration of A. Sample prep- aration and measurement methods were described in detail. In a further paper the same group reported the results of studies on the tissue disposition of A in a normal and a uraemic rat. Bone A levels in the uraemic rat were twice those in the normal rat whereas all other tissues had similar A concentrations.The authors suggested that bone of ura- emic individuals may have an increased affinity for Al. Using AAS to determine tissue Al Cu and Zn concentrations Ogoshi et al. studied trace element accumulation in cancers of the liver stomach duodenum and mammary glands of rats administered -methyl-dimethylaminoazobenzene. Aluminium concentrations were significantly elevated in carci- nomas of all tissues studied. Kandiah et al. also used AAS to determine tissue A concentrations in rats fed soft drinks packaged in different materials. Rats fed soft drinks packaged in A cans had significantly higher blood liver and bone A concentrations than rats fed glass bottled soft drinks. Finally the paper by Savory clearly establishes the relevance and importance of accurate methods for the determination of A in clinical specimens.The paper gives an excellent review of the studies that led to the identification of iatrogenic A poisoning of dialysis patients and the subsequent development of monitoring strategies. Antimony For the accurate determination of Sb at ng -' levels in environmental and biological samples Enger et al. developed a laser induced fluorescence LF -GF method using an intensified charge coupled device ICCD for signal detection.The authors demonstrated significantly improved spectral selectivity with the ICCD compared with a conven- tional photomultiplier giving much higher analytical sensitivity and better background correction capability. Determination of Sb in pure water gave an LOD of. ng -' and values determined for Sb in riverine and marine sediment CRMs were in good agreement with certified values. The method was used to study possible sources of Sb contamination during collection of blood samples. Collection into plastic tubes with EDTA as anticoagulant was found to give the least Sb contamination. Levels of Sb determined in whole blood from healthy individ- uals ranged from < ng -l to ng -I. A more conventional approach using ETAAS was employed by Smith et al. to determine urinary Sb levels in unexposed and occupationally exposed individuals. Urine samples were acidi- fied with HCl heated to reduce SbV to Sb"' and the Sb extracted with ammonium-N-nitrophenylhydroxylamine into IBMK for determination by ETAAS.The LOD for the method was. pg I-' and an analytical precision of.% RSD was reported. The mean urine Sb concentration in non-exposed individuals was. pg -'. Levels of urine Sb measured in three groups of occupationally exposed workers were markedly elevated compared with unexposed individuals. The distribution of Sb in tissues of hamsters infected with.Leishmania gurnhami and treated with N-methylglucamine itntimoniate was studied by Yarbuh et al. using IHG-AAS. Serum Sb"' and SbV concentrations were similar after im and intra-lesional administration of the drug.Total R Journal of Analytical Atomic Spectrometry April Vid. Sb concentrations were highest in heavily parasite infected tissues particularly the spleen and ulcer lesion. Jaser et al. used an ETAAS method to study the pharmaco- kinetics of Sb in patients with cutaneous leishmaniasis follow- ing im administration of sodium stibogluconate mg Sb. Both whole blood samples and h urine samples were simply diluted with Triton X- for determination of Sb. The mean maximum concentration of Sb in blood was. mg -'and was observed. h after administration. The fraction of the dose excreted in the urine was %. Based on area-under-the- elimination curve measurements patients could be divided into slow Sb eliminators high internal Sb exposure and rapid eliminators low internal Sb exposure. Arsenic Establishing the source of As measured in human bodyjuids for occupational and environmental exposure assessment requires analytical methods capable of determining the major inorganic and organic As species found in biological systems. Consequently many groups have focused their attention on this analytical challenge Although coupled HPLC-atomic spectroscopic techniques are now reasonably well established improved methods continue to be developed for this appli- cation.The coupled technique of HPLC-ICP-MS has been used by several groups to determine inorganic and organic As species in human urine and in extracts of fish and shellfish. Inoue et al. separated As"' AsV monome- thylarsonic acid MMA dimethylarsenic acid DMA arseno- betaine AsBe and trimethylarsine oxideTMAsO in human urine by ion-exchange chromatography for ICP-MS detection using a hydrophilic polymer-based anion-exchange resin. Detection limits for the individual species ranged from.-. pg l-'As and reproducibility was better than % RSD. Caroli and colleagues also used an anion-exchange resin for ion-chromatographic separation of AS"' AsV MMA DMA arsenobetaine and arsenocholine from fish and mussel extracts. A hydrogencarbonate gradient eluent gave optimum separation for detection by ICP-MS. Limits of detection between. and. pmol -' As were reported for As species. Micellar LC was used by Ding et al. to separate the four major As species AS'" AsV MMA and DMA from human urine for ICP-MS determination of As. The chromatographic mobile phase contained. mol -' cetyltrimethylammonium bromide % CH,H and. mol -l borate buffer. Urine was injected directly into the chromatography system with minimal pre-treatment. No C- interference effects were observed. A particularly interesting and extensive study of As speciation was described by Le et al.They studied the urinary As excretion patterns in a group of nine volunteers who ate various seafood known to be rich in As. Urinary As species were separated by HPLC on a reversed phase column and detected in the column eluent by ICP-MS. Total urinary As was determined by HGAAS after microwave digestion of the urine matrix. Following a single ingestion of shellfish fast urinary excretion of arsenobetaine was observed whilst arsenosugars were metabolized and retained longer in the body. Following ingestion of seaweed as many as six urinary As species could be detected and the urinary excretion pattern varied from individual to individual.The authors suggested that enzyme or microbial activity in the body may be responsible for metabolism of arsenosugars. The effect of cysteine as a reducing agent on the determination of As species by HGAAS was also studied by this group. The addition of % cysteine to samples prior to HG led to different As species giving equivalent analytical responses allowing a single As species to be used for calibration. The authors considered that cysteine reduced all As species to the As"' state as organo-S-As"' species. Pergantis et al. C described an HPLC-ICP-MS method for the determination of organo- arsenic compounds used as animal feed additives. The use of conventional columns and micro-columns and different nebuli- zers for eluent introduction to the plasma was investigated. Various extraction sample preparation methods for the determination of As species in biological samples by coupled spectroscopic techniques were evaluated by Alberti and col- leagues. Several solvents and solvent-aque- ous mixtures were examined for extraction efficiency and analytical compatibility with the detection system. A CHH-H v v mixture was considered to be the best extraction solvent. For separation of extracted As species the group used anion exchange chromatography with a buffer. Detection was by HG-ICP-OES following UV irradiation of the eluent stream.Thomas and Sniatecki also used a repeated methanol-H,O extraction procedure for the determination of As species in marine biota by anion-exchange chromatography and ICP-MS detection. In their method a tetrabutylammonium phosphate-NaHP eluent at pH was used for separation of As species. Limits of detection for the species ranged from - pg -'. HPLC with HGAAS detection is equally suitable for As speciation studies and was used by Jimenez de Blas et al. to determine urinary As metabolites in individuals not occu- pationally exposed to As. Chromatographic separation was performed on AGW-X resin in the cationic form with sequential elution of As"' plus AsV MMA and DMA using. mol -' HC H and % NH, respectively.The eluent was collected in ml fractions which were subsequently ana- lysed by FI-HGAAS. Momplaisir et al. described the development of a novel silica T-tube interface for the detection by AAS of As and Se in HPLC column eluates. Analyte in either aqueous or organic mobile phase was com- busted in a H,- atmosphere within a heated pyrolysis chamber in the lower portion of theT-tube and flushed into the unheated optical section of the tube by gaseous expansion. The interface design gave equivalent signal responses for As and Se in various oxidation states and gave low ng.LODs for As oxyanions arsonium cations Se anions and Se amino acid species. The method was evaluated by analysing biological CRMs. Methods for the accurate quantification of total As in biological samples also continue to be developed. Methods for the determination of total As and arsenobetaine in the muscle and liver tissue of marine fish were described by Ballin et al. Total As was quantified by HGAAS following acid mineralization of homogenized samples. Arsenobetaine was extracted from homogenized samples with CHC-CHH-H. A portion of the extract was hydrolysed with NaOH for headspace GC with coupled AAS detection. On average arsenobetaine represented % of the total tissue As in the fish examined. Various acid digestion procedures were evaluated by Hanna et al. for the determination of inorganic As and its primary metabolites in urine by FI-HGAAS. In the procedure giving best analytical recovery of all major As species non-toxic arsenocholine and arsenob- etaine species were removed by a solid-phase extraction pro- cedure and the remaining sample was digested with HNO-H,SO-KzCr,.The AsV in the digest was reduced to As"' with KI in HCl before injection into the FI manifold. Recoveries for the four major As species ranged from % for DMA to % for AsV.The effect of different chemical modifiers on the atomization temperature of As in ETAAS was investigated by Hirano et al. The group used a multi-channel AAS instrument to study the atomization behav- iour of As with Pb as a reference element. The presence of Ni and Pd increased the As atomization temperature. Addition of K suppressed this phenomenon and gave a clear absorbance signal for As in urine. The determination of total As in Journal of Analytical Atomic Spectrometry April Vol. I R biological samples by ICP-MS has been described by four groups. Huang et a!. used a continuous flow HG system without a gas-liquid separator for sample introduction to the ICP-MS. The application of HG for sample introduction overcame the interference and sensitivity problems aswciated with normal solution pneumatic nebulization.The arsenic in the sample was reduced to As"' with cysteine before injection into the HG system. The method was successfully applied to the determination of As in a variety of biological CRMs. Campbell et al. reported important findings concern- ing the determination of total As in biological matrices by ICP-MS. They demonstrated an element-specific enhancement of the As signal up to a factor of arising from differences in the acidity of samples and external calibration solutions. The authors considered the presence of a carbon containing matrix was central to this phenomenon and concluded that matrix-matched calibration to minimize differences in acidity and carbon loading was essential for accurate quantification of As by this technique. Matrix interference effects on the determination of As and Se in urine by He ICP-MS was investigated by Nam et al. Enhancement of the As signal was found in the presence of Na U and S- but could be overcome by using Se as an internal standard. Good results for NIST urine SRM were obtained using standard additions calibration and internal standardization with Se. Various sample digestion procedures were evaluated by Lasztity et al. for the determination of total As in soil dust diet and faecal samples by ICP-MS. In what has been described as the greatest As calamity in the world Das and colleagues described the results of studies on the determination of As in groundwater and drinking water and concentrations of As in biological samples collected from affected people living in districts of West Bengal. Water and urine samples were analysed by FI-HGAAS following various pre-treatment steps including ion-exchange chromatography and chelation-solvent extrac- tion to speciate As.Tissue nail and hair samples were analysed by either FI-HGAAS or Zeeman effect ETAAS following acid digestion.The source of the As was shown to be geological and concentrations of As"' and AsV in all water samples analysed exceeded the WHO permissible limit of. mg -' ranging from. mg -' to. mg -'. The most toxic As"' species represented about % of the total As in the water samples and % of urinary As was inorganic in origin. Of the population of million in the affected region at least people were found to be drinking the water and were showing late symptoms of As intoxication includ- ing melanosis conjunctivitis de-pigmentation and hyperkera- tosis.The use of human hair as an indicator for body burden of As was discussed by Komberkova and Novobilsky C. Samples of hair from subjects with alopecia and controls were analysed for As. Hair As was determined by HGAAS following acid mineralization with HNO-HSO-HO. The results showed no correlation between skin disease and hair As content. The axial distribution of As in individual human hairs was determined by Koons and Peters using ETAAS with a cup-in-tube solid sampling device. A chemical modifier of Pd-Mg was necessary for accurate quantification and a detection limit of. pg -' was reported. For the determination of As in Chinese patent drugs by ETAAS Huang used a chemical modifier of NiS.The drug samples lOmg As were digested with HS-NH S-KS and the digest diluted to ml with % HS. Recoveries of As ranged from.%-% and no interferences were found. Barium. The eflect of diflerent graphite tube surfaces and atomizer sheath gases on the determination of Ba by ETAAS was investigated by Montiero and Curtis. The use of N as sheath gas gave reduced analytical sensitivity through the formation of BaCN. No improvement in analytical sensitivity was found with W pre-treatment of the graphite tube. Optimum analytical performance and longest tube lifetime were obtained with Ar sheath gas and wall atomization from a pyrolytically coated tube. Standard additions calibration was considered necessary for the measurement of Ba in biological matrices. Occupational exposure to Ba occurs in the cosmetic and pharmaceutical industries and particularly in welding processes using materials with a high Ba content. In such welding activities localized air concentrations may reach mg mP.The determination of Ba in plasma or urine by ETAAS or ICP-OES was recommended by Zschiesche and Schaller for monitoring such occupational exposures to sol- uble Ba compounds. For both analytical techniques urine samples were diluted and plasma samples deproteinized with HNO,.In non-occupationally exposed individuals absorption of Ba from the diet could lead to variations in urinary Ba levels between. and pg -'. By comparison urine Ba levels up to pg -' were measured in welders with high Ba exposures. The authors advised that in cases of low occupational exposure there could be considerable overlap between the values of Ba arising from occupational exposure and dietary intake. Consequently biological monitoring could only be recommended on a group basis. Beryllium For the determination of Be in acid digests of biological materials by ETAAS Nakagawa et al. used an MgNO chemical modifier to improve the thermal stability of the analyte.The accuracy of the method was verified by analysis of NIST SRMs and an LOD of pg g-' was reported. The concept of standardless analysis by ETAAS was applied by Yang and Ni to the determination of Be in biological samples. Solid- samples were digested with HN-HC-HF for analysis. Urine samples were simply diluted with H. Using a chemical modifier with platform atomization and peak area measurement a characteristic mass of. pg was calculated.The method was subsequently used to estimate the Be concentration in digested or diluted samples. Bismuth Luppino and McLean used HGAAS to determine Bi in plasma urine and tissues of normal and cirrhotic rats administered Bi subcitrate in a study of the effect of liver disease on the total body handling of Bi. Samples were digested with HNO and re-dissolved in HC for analysis. For all digested materials matrix-matched calibration curves were linear to pg - ' and analytical precision RSD at pg -' Bi ranged from to %. Urinary Bi clearance was significantly reduced in cirrhotic rats after d of administration of Bi subcitrate leading to the accumulation of Bi in several tissues. The authors suggested that monitoring of Bi levels might be necessary for patients with liver impairment receiving thera- peutic Bi.The distribution of Bi in the brain and peripheral nervous system of mice following administration of a neuro- toxic intraperitoneal dose of bismuth subnitrate BSN was studied by Ross et al. using AAS and autometallogra- phy. Bismuth concentrations were highest in the olfactory bulb hypothalamus septum and brain stem. The accumulation of Bi was associated with diffusion of Bi from fenestrated blood vessels in these regions. The authors proposed that this process was a contributory factor to the observed neuropathology. The effect of Omeprazole a drug used in the treatment of acute peptic ulcers on absorption of Bi from tripotassium dicitratobismuthate was investigated by Treiber et al. Plasma and urine concentrations of Bi were R Journal of Analytical Atomic Spectrometry April. determined by AAS. Plasma Bi concentrations and urinary Bi excretion were increased following Omeprazole treatment com- pared with the placebo. A significant correlation between intragastric pH and excretion of Bi was observed. Boron.The injuence of various analytical factors on the determination of B in several biological matrices by ICP-MS was critically examined by Evans and Krahenbuhl. Following microwave digestion with HNO, B was determined by ICP-MS using external calibration standard additions and isotope dilution. All three calibration modes gave accurate and reproducible results for four biological CRMs. External cali- bration was considered the most suitable however for its speed and simplicity. Matrix effects were corrected for with Be as an internal standard and memory effects were minimized by using a wash solution of NaF between determinations. Boron concentrations of. pg g-' were determined accu- rately.The same workers compared the analytical performance of ICP-MS with ICP-OES photometric and fluorimetric methods for the determination of B using the same four biological CRMs as in the previous study. Good analytical precision and accuracy were obtained with both ICP methods. The photometric method using azomethine-H was only accurate at elevated B concentrations whilst the fluorimetric method gave no acceptable results. A rapid ICP- OES method for the determination of B in whole blood was described by Bauer et al. in which the blood sample was introduced in the plasma as a slurry with non-ionic surfactantTriton X-. The concentration of surfactant selected minimized cell destruction and reduced the inter- ferences from alkali metals. Moseman also described an ICP-OES method for the determination of B in blood bone and soft tissues following HNO microwave digestion of samples. Limits of detection for different tissue matrices ranged from. to.mg -'. The method was used to determine blood and tissue B concentrations in rodents fed a diet containing ppm boric acid. Boron concentrations in blood and soft tissues reached a plateau of pg g-' after d administration. Both ICP-OES and ICP-MS methods were used by Lidstroem et al. to determine the intracellular uptake and binding of three new-generation carborane-based anti- tumour agents ANC DAC and B-Et-Ome in cultured human glioma and mouse melanoma cells. Cells were exposed to the compounds at concentrations equivalent to - ppm B for h and drug binding assessed by measuring cell B content. Cells treated with the DAC and B-Et-Ome drugs accumulated and bound B to levels and times the concentration in the culture medium. Cells treated with ANC also accumulated B but this was weakly bound and easily removed by cell washing. Following administration of the anti- tumour agent borocaptate sodium to dogs with spontaneous intercranial tumors Kraft et al. used ICP-OES to determine the biodistribution of B in tumour and normal brain tissue. Mean B concentrations were elevated in both extracer- ebral tumors. pg g-' and intracerebral tumors. pg g-' h after administration of the drug. Peritumor concen- trations of B also exceeded normal brain tissue B levels.Tumour blood B ratios ranged from. to. In an unusual study described by Green and Ferrando the influence of B supplementation on plasma testosterone lean body mass and strength improvement in male bodybuilders was investi- gated. Plasma B concentrations were determined by ICP-OES following microwave digestion. Boron supplementation had no effect on any of the above parameters thereby dispelling another theory concerning the benefits of mineral supplementation. Cadmium.The effectiveness of various sample pre-treatments and chemi- cal modifiers for the direct determination of Cd in body fluids by ETAAS has been examined by several groups. De Fatima et al. evaluated different Pd based chemical modifiers for the quantitative determination of Cd in whole blood and urine.The modifier was injected and pyrolysed at OC to remove contaminating Cd prior to injection of the diluted sample. Blood samples were diluted + v v with Triton X- and urine samples + v v with.% HNO,. With a Pd N -MgN chemical modifier and the double injec- tion decontamination procedure an LOD of. pg -' Cd was obtained for both matrices. Matrix-matched calibration standards were essential in obtaining good agreement between measured values and certified values for biological CRMs. Hosoda et al. found that a five-fold dilution of blood with addition of PdN as chemical modifier and a two- fold dilution of urine with NHHP as chemical modifier gave the best results for the determination of Cd in these matrices. On the other hand Dulude et al. C found that no chemical modification was necessary for the simul- taneous determination of Cd and Pb in blood by ETAAS using a spectrophotometer capable of determining four elements in a single atomization. Matrix and spectral interferences on the determination of Cd were overcome by precipitating the pro- teins prior to analysis and with the use of Smith-Hiefje background correction.Three digestion procedures for the determination of Cd Cu and Pb in Chinese herbal medicines were compared by Jung et al. The first involved dry ashing followed by HNO digestion the second employed wet digestion with HN-HC-HC and the third autoclave digestion at "C. Digests were filtered and diluted with H for elemental determination by FAAS. The LOD for Cd was. pg -'. The best results were obtained with the autoclave digestion procedure. Although for many investigations the determination of Cd in biological fluids by ETAAS can be performed directly methods continue to be described which employ pre- concentration steps to overcome interference problems and obtain better analytical sensitivity.This approach was taken by three groups to determine Cd in blood and other biological samples. Espinosa et al. determined the optimum conditions for the extraction of Cd from biological samples with the chelating agent ,-bisdi-pyridyl-methylene thiocarbohydrazide DPTH. A maximum extraction ratio of was possible for -% extraction of the metal into IBMK and an LOD of. pg -l was reported. To improve the sensitivity for the determination of Cd in blood by ETAAS Peterson et al. described a patented chelation and extraction method which used an anion-exchange resin. Using the developed kit approximately % of the contaminating material was removed from the blood sample and the eluent from the resin contained >% of the original Cd content. Dong and Fang developed an on-line FI system for the extraction and pre-concentration of Cd from the same matrix. Cadmium was precipitated from the digested blood sample with an acidic solution of dithizone onto a knotted coil reactor column and micro-membrane filter.The precipitate was dissolved in pl IBMK and transferred into the graphite furnace for determination by ETAAS. This treat- ment gave an enrichment factor of and an LOD of. pg I-'. The method was validated by accurate determination of Cd in blood CRM GBW. For the determination of Cd in biological samples by FAAS a pre-concentration step is often essential to achieve the necessary sensitivity.The same authors applied the above system to the determi- nation of Cd in hair by FAAS using Na diethyldithiocarbamate to complex Cd from the acid digested matrix and eluting the adsorbed complexes with IBMK directly into the nebulizer of Journal of Analytical Atomic Spectrometry April Vol. R the AAS. Pre-concentration by chelation and solvent extraction was used by Siles Corder et al. for the determination of Cd in biological samples by ICP-OES. Powdered samples were digested with HN,-HCl neutralized with NaOH and diluted with NaC,-acetate buffer. Cadmium was extracted with.% DTPH in IBMK and Cd determined by ICP-OES at the. nm Cd line. An interesting and important study of Cd speciation in human urine and perspiration was described by Chang and Robinson.The Cd species were separated by HPLC on a C column with an H mobile phase and the eluent fed to an FAAS instrument through a novel thermospray interface. The eluent was vaporized and desolvated in the interface chamber and the dried analyte delivered directly to the base of the flame of the spectrophotometer. This arrangement produced a twenty-five-fold enhancement in sensitivity over conventional nebulization. With this system the authors separ- ated several non-volatile Cd species from both matrices. Their studies showed that the patterns of Cd excretion were quite different in the two matrices and that Cd concentrations were markedly higher in perspiration than in urine suggesting that this may be a major route of Cd excretion. From the Cd excretion data the authors calculated a Cd half life of. y which is considerably lower than previously reported values. Both HPLC-AAS and HPLC-ICP-MS coupled techniques were used by High et al. to study the binding of Cd to metallothionein proteins extracted from mussel tissue. In the presence of the reducing agent -mercaptoethanol metallo- thionein had a higher Cd content than in the absence of the reducing agent.The authors suggested that the metallothioiiein fraction may be partially oxidized in vivo or during isolation and therefore conventional metal saturation assays may not be suitable for quantification of metallothionein in mollusc tissue. Chan et al. used gel permeation chromatography followed by AAS to determine free and bound Ag Cd Cu and Zn in lobster digestive gland extract. Homogenized tissue was chromatographed on Sephadex GlOO with CHCNH buffer.The Cd Cu and Zn content of the eluent fractions was determined by FAAS. With TSF a proteinase inhibitor added to the homogenization buffer Cd and Cu were determined in both high and medium molecular weight fractions. In the absence of the inhibitor Cd was released from the proteins. The concentration of Cd in livers of deer was determined by Musante et al. Liver tissue was digested with HNO and diluted with H for determination of Cd by ETAAS. Concentration of Cd in the livers ranged from. to. pg I-' with a mean value of. pg -'. Elsenhans and colleagues studied the longitudinal distribution of Cd Cu Fe and Zn in the small intestine of the rat following parenteral and oral administration of CdC.Tissue metal levels were determined by FAES and metallothionein concentrations by RIA. Oral administration of Cd resulted in an increasing Cd concentration gradient from the duodenum to ileum which paralleled that of metallothionein. Levels of Cu were increased and Fe reduced in the mucosal tissue of the Cd-fed rats. In contrast injected Cd neither induced an intestinal metallo- thionein gradient nor altered intestinal concentrations of other metals. The involvement of Cd in hypertension was investigated by Tomera et al. who used a rabbit model to study the inter-relationship between Ca Cd and heart hypertrophy. Tissue Ca and Cd levels were determined by FAAS. Relationships between the measured parameters were evaluated by regression analysis and two dimensional vectorial analysis. Inter-relationships between Ca and Cd levels were observed in the left ventricle aorta and renal medulla. Calcium A current major drawback with most atomic absorption spectrophotometric techniques is the limitation of single element determination.To overcome this problem Araujo and colleagues developed an FI system for the simultaneous determination of Ca by AAS and Nu or K by FAES. The FI system incorporated a dialysis unit for sample dilution and stream splitting of the sample plug for parallel detection of the two elements by the named techniques. An optimization algorithm method was employed to achieve the best performance of the system. The method was evaluated by analysis of quality control sera and comparing results obtained for normal serum samples with those determined by individ- ual AAS and FAES reference methods. Good agreement between the two data sets was observed.The system was capable of up to analyses h-'. A different approach was adopted by Zhang et al. for the determination of Ca and P in serum. In their system Ca and P were measured sequentially in the same sample by FI with UV VIS and AAS detectors connected in series. Analytical recoveries of.% for P and % for Ca were found. Cai et al. used FAAS to determine Ca in rat cardiac muscle. Muscle tissue was digested with HN-HC and the digest solution directly introduced into the nebulizer of the AAS. The method was used to study the effect of procaine and ,-dinitrophenol on cardiac muscle Ca concen- trations. Flame AAS with an air-CH flame was also used by Yuan et al. to determine Ca and Na in gallstones from human subjects. Huang et al. developed a micro-sampling method using a pl micro-injector to deter- mine Ca concentrations in cochlear perilymph fluid from rats suffering from rickets. One microlitre volumes of the perilym- phatic fluid were collected from rats killed by pentobarbital and diluted with pl of.% La solution for determination by FAAS.The linear range for the method and analytical precision for p volumes were - mg -l and.-.% RSD respectively. A DCP-AES method was described by Petersson for the simultaneous determination of Ca Mg and P in rat tissues. Samples of heart and kidney were wet digested and dissolved in ionic buffer. Aortic tissue was dissolved in mol -' HNO,. The method was evaluated by analysis of four CRMs. Recoveries of Ca Mg and P ranged from -% and analytical precision ranged from. to.The use of ,'Ca for Ca metabolism studies was described by two groups. Southon et al. used the isotope with AMS detection to study Ca uptake and deposition in isolated rabbit heart tissue during cardiac ischemia. Johnson and colleagues used the same technique to investigate Ca resorption from bone in a human volunteer following injection of Ca tracer. The fate of the injected dose was followed over a period of years by measurement of Ca in serum and urine. A quasi-steady state ,'Ca:Ca ratio of. x lo-'' was reached at d post-injection. The authors considered that variations in this ratio would indicate changes in the rate of Ca re-sorption from bone. The effects of a moderate increase in maternal dietary Ca on maternal and foetal trace element interactions was investi- gated by Shackleford et al. using ICP-OES for trace element determinations. In pregnant rats dose-related decreases in the Fe content of liver and Fe Mg and Zn content of kidney were observed following Ca supplementation. ]Foetuses from rats with Ca supplementation had dose-related decreases in total body contents of Cu Fe Mg and P. A particularly exciting development in trace-element analysis was described by Nomizu et al.This group developed an analyser capable of determining the Ca content of individual biological cells in real time by ICP-OES. A suspension of cells in % ethanol was sprayed through a Meinhard concentric nebulizer in a drying chamber. The droplets were rapidly dried in a stream of air min-' and directly introduced into the plasma. Signals from the photomultiplier generated by.% RSD. R Journal of Analytical Atomic Spectrometry April Vol. I emissions at the. nm Ca line from single cells in the plasma were amplified and the pulses measured by a multi- channel pulse-height analyser.The system was calibrated with a monodisperse aerosol of Ca acetate produced by a vibrating orifice aerosol generator. Calcium concentrations determined in several mammalian cell lines ranged from. to. pg cell per cell. The LOD was. pg cell per cell. The authors considered that the present pneumatic nebulizer gave a poor introduction efficiency to the plasma of. YO which could be improved with a vibrating orifice nebulizer. The present detec- tion system was not sufficiently sensitive to determine individ- ual cellular concentrations of other trace elements but the authors considered that detection by ICP-MS could overcome some sensitivity limitations. Chromium.The unresolved question of the importance of background correction for the reliable determination of Cr in biological fluids has continued to promote work on this topic. A particu- larly interesting and useful study was described by Granadillo et al. in which total Cr was determined in whole blood blood fractions urine and acid-digested bone by ETAAS using a fast-furnace programme. Blood matrices were diluted + v v with.% Triton X- urine was diluted + v v with.% Triton X-. mol -' HNO, and bone + v v with. mol -' HNO after microwave digestion. Chromium determinations were made using two alternative instrumental configurations a longitudinally heated atomizer with wall atomization and continuum source background correction and a transversely heated furnace with Zeeman effect background correction and STPF conditions. For both configurations an ashing temperature of "C and atomiz- ation temperature of °C gave the best absorbance signal.Total time for the furnace programme was - s for a pl injection volume. Using the above conditions the authors found that neither background correction nor chemical modi- fication in this paper termed analyte isoformation was neces- sary for accurate quantitation of Cr. With wall atomization and continuum source background correction a detection limit of. pg -' and precision of % RSD were achieved compared with an LOD of. pg -land precision of.% RSD for Zeeman effect background correction and STPF conditions.The accuracy of both methods was verified by analysis of biological CRMs. The authors used both methods to determine reference values for Cr in whole blood plasma serum and urine of healthy individuals chronic renal failure patients and diabetic subjects from Maracaibo city Venezuela. Background correction in the determination of Cr in serum and urine matrices by ETAAS was also studied by Egila et al. In this study the performance of two commercially available spectrophotometers with Zeeman effect background correction was examined. The authors observed that both peak height and peak area background signals generated by serum and urine matrices differed considerably between the two instruments both at the Cr absorbing. nm line and non- absorbing. nm line.The instrument giving the better analytical performance was able to correct for background signals of. A peak height and at least. A s peak area. Zeeman effect background correction was also recommended by Rubio et al. for the determination of Cr in urine following evaluation of the performance of both deuterium source and Zeeman effect background correction systems for this difficult matrix. Analytical precision was improved with sample dilution and slow hot injection. Hirano et al. took the approach of multiple injections to improve sensitivity for the determination of Cr and Ni in whole blood and serum by ETAAS. Whole blood and serum samples were diluted two- or three-fold with a Pd-Triton X- chemical modifier. Sample injection drying and ashing steps were repeated five or ten times before atomization.To improve ashing of the organic matrix and prevent excessive build up of carbon residue an alternate gas containing % was used in the ashing step. On the other hand Fang et al. reported an accurate and precise method for the determination of Cr in serum by ETAAS in which samples were simply diluted with an equal volume of.% HNO,. Calibration was by standard additions and the analytical sensitivity was pg for a signal of. A. Judging by the paucity of articles on this topic solid sampling ETAAS still does not appear to be widely used for the analysis of biological materials. This approach however was adopted by Minami et al. for the determination of Cr at sub-pg g-' levels in a variety of powdered biological samples.The authors presented a three-point standard addition calibration procedure as an alternative to calibration with aqueous standards. Good agreement was found between values of Cr determined for a variety of biological materials by the two calibration methods. More importantly the authors reported that the standard addition calibration prepared in one matrix could be applied to other types of biological sample. The accurate determination of Cr in biological matrices by ICP-MS is complicated by interferences from the polyatomic ions C ,%lOH and Ar'C. In an effort to minimize these interference effects Lam et al. undertook a detailed investigation of alternative sample preparation methods and instrumental conditions. For the elimination of polyatomic interferences originating from C the use of a mixed air-Ar nebulizer gas and isotope dilution analysis was found to be most effective.The relationship between Cr exposure and DNA damage in a group of workers occupationally exposed to low levels <. mg mP Cr" of Cr compounds was investigated by Faux et al. Chromium levels in whole blood lympho- cytes plasma and urine were determined by ETAAS. Chromium levels were markedly elevated in the blood plasma and urine of exposed workers compared with controls. pg -' versus. pg -',. pg -' versus. pg -' and. pg mmol-' of creatinine uersus. pg mmol-' of creatinine respectively whereas there was little difference in lymphocyte Cr levels. pg-" cells uersus. pg-" cells. No sig- nificant difference in the extent of DNA damage was observed between the exposed and control groups.The authors con- sidered that the current UK maximum exposure limit for CrV of. mg rn- may have achieved its goal of minimizing the health risk to workers exposed to CrV' compounds. Fang and colleagues studied the role of ascorbic acid in promoting Cr"' absorption in humans. Volunteers ingested mg Cr"' with or without ascorbic acid and blood samples were periodically taken up to h following ingestion. Plasma Cr levels were determined by ETAAS following partial enzymic digestion of the matrix. Plasma Cr levels were consistently significantly higher when Cr was ingested with ascorbic acid. The authors suggested that concomitant ingestion of ascorbic acid with Cr in the diet may be an important factor in maintaining Cr balance and preventing Cr deficiency. Cobalt A comparison of ETAAS ICP-MS and CSV methods for the determination of ultra-trace levels of Co in whole blood serum and plasma was undertaken by Godlewska et al. For measurements of Co in serum and plasma by ETAAS no sample pre-treatment other than dilution with % HNO was necessary. For all other analyses samples were digested with HNO + v v for h at °C. Digested samples were further diluted -fold with H and UV irradiated for CSV analysis.The authors concluded that ICP-MS was the preferred Journal of Analytical Atomic Spectrometry April VoZ. R method for these matrices owing to its wide dynamic range and low LOD. pg -l. The eflect of diflerent acid matrices and chemical modifiers on the determination of Co in human hair by ETAAS was investi- gated by Xiang et al. A method was described in which NaSi was used for thermal stabilization of the analyte. An ETAAS method derived from the IUPAC reference method for Ni was developed by Baruthio and Pierre for the determination of Co in both serum and urine matrices. Following a wet digestion step Co was pre-concentrated by extraction with APDC into IBMK. Limits of detection were. and. nmol I-' for serum and urine respectively. Analytical precision ranged from. to.% RSD for both serum and urine at Co concentrations of nmol -' and nmol -' but increased to.% RSD for serum and % RSD for urine at Co concentrations below nmol I-'. Ammonium pyrrolidinedithiocarbamate was also used to pre- concentrate trace Co for determination by FAAS in a method described by Dong and Feng for the determination of Co in biological samples.The Co-APDC complex was precipitated on a cm long knotted PTFE reactor column and eluted with IBMK.The pre-concentration and elution was performed on-line by directly coupling the FI system to the nebulizer of the spectrophotometer. With this approach an enrichment factor of was achieved giving an LOD of pg -'. The method was evaluated by determining Co in NIST bovine liver SRM. Good agreement with the certified value was reported. Perez and Sanz-Medel found that simple + v v dilution with H and use of a PdN chemical modifier was satisfactory for the quantitative determi- nation of Co in serum by ETAAS. With standard additions calibration an LOD of. pg -' was reported. Precision was % RSD at a Co concentration of pg -'. The authors used the method to measure serum Co levels in chronic renal failure patients either undergoing maintenance haemodialysis or treatment with desferrioxamine DFO for A detoxification. A mean serum Co level of. pg I-' was found in dialysis patients compared with a value of pg -' Co in patients having undergone DFO treatment. It was interesting to see that the novel 'in-vivo' sample uptake technique developed by Burguera et al. and described in the previous review has been used by the same group for the determination of Co in whole blood by ETAAS. In this study the sample uptake and on-line microwave digestion system were coupled through a timed solenoid injec- tor to the ETA.The spectrophotometer autosampler was also re-programmed to inject an MgNO chemical modifier in synchronization with the FI system. The method gave a linear calibration range of - pg -' with an LOD of. pg -l and precision of.% RSD at pg -' Co. Good agreement with values for Seronorm whole blood RM was reported.The damaging effect of Co on prenatal development in rodents and rabbits was investigated by Szakmary et al. The authors used ETAAS to determine Co in maternal blood foetal blood and amniotic fluid following administration of CoSO to pregnant animals. After adminis- tration of the compound Co concentrations in maternal blood increased proportionally to the administered dose and Co appeared in foetal blood and amniotic fluid. Cobalt was found to be embryotoxic in all species studied increasing the inci- dence of foetuses with growth retardation. Cobalt was also found to be teratogenic in rats and mice. The authors concluded that the embryotoxicity and teratogenicity of Co were a result of direct cytotoxic action of Co.To study the pharmacokinetics of Co and Co-protoporphyrin Rosenberg used ETAAS to determine Co in plasma and tissues of rats following subcutaneous administration of inorganic Co or Co-protoporphyrin. Cobalt was rapidly eliminated from plasma with a half-life of h whereas Co-protoporphyrin complex was eliminated much more slowly half-life = d. Elevated levels of Co - pg -' were retained in the kidney up to four weeks after administration of inorganic or com- plexed Co. In the case of Co-protoporphyrin administration elevated levels of Co were also observed in the spleen lungs thymus and gonads. Copper Methods for the determination of Cu in various body fluids using AAS techniques have been described by several groups. A rapid ETAAS method was developed by Wang and Demshar for the determination of Cu in serum and urine.The same diluent,.% HN-.% Triton X- was used for both matrices with serum and urine being diluted + v v and + v v respectively. The LODs were. pmol -' for serum and. pmol I-' for urine. Two methods for the determination of Cu in micro-samples of whole blood and serum have been described. In the method of Yan et al. pl samples of whole blood taken from the ear were diluted ten-fold with.% Triton X-. Twenty microlitre aliquots of the solution were analysed for Cu by first-order derivative FAAS. A two-hundred-fold improvement in the signal was observed compared with normal nebulization FAAS. In the method described by Ji et al. pl volumes of serum were diluted + v v with. mol -l HNO for determination by ETAAS. With a normal graphite tube calibration was linear from.-. mg -' Cu. A ten- fold dilution of serum effectively eliminated interference effects. Both tear and serum Cu levels were determined by AAS in a study described by Osman et al. Mean tear and serum Cu levels determined in a group of healthy individuals were. mg - ' and. mg - ' respectively. No correlation between tear and serum Cu concentrations was observed. Electrothermal AAS was used by Gao et al. to determine levels of Cu and Fe in vitreous and aqueous humour. Samples were diluted + v v with mmol -' HNO and pl volumes injected into the furnace.The precision for the method ranged from. to.% RSD. A simple FAAS method for the determination of Cu and Zn in liver samples from NZ rabbits was described by Gong et a!. Liver samples were digested with HN-HC-HS in sealed vessels and the digest diluted with H.The detection limit for Cu was. mg -'. '. The role of serum proteins in the binding and transport of Cu was investigated by Vargas et al. using an analbuminaemic strain Nagase of rat. Higher serum levels of Cu were determined in Nagase rats compared with Sprague- Dawley rats which was accounted for by an increase in serum caeruloplasmin levels. However the distribution and tissue uptake of injected Cu was unaffected by the absence of albumin. In the case of Nagase rats the initial binding of Cu was to transcuprein rather than albumin. Analysis of tissue Cu concentrations by AAS showed no significant differences between the two strains of rat. The authors concluded that albumin was not critical for the normal distribution of Cu and may simply act as a resource for excess Cu rather than as a specific transport protein.The distribution of Cu amongst cellular proteins in rainbow trout poisoned with CuSO was studied by Campbell et al. using AAS to determine Cu in protein fractions of liver homogenate separated by HPLC. A higher concentration of Cu in proteins of - k molecular weight was observed in CuS,-exposed fish. Bihoreau et al. used ETAAS with Zeeman effect background correction to determine Cu in preparations of human blood coagulation factor VIII F-VIII. Copper was identified in the active F-VIII trimer and also in the inactive dimer. Further dissociation however led to a loss of Cu and activity. The authors suggested that Cu is essential for the R Journal of Analytical Atomic Spectrometry April Vol. structural integrity of the protein but is not directly involved in clotting activity. Changes in Cu status in various disease states has also been studied by a number of groups using AAS techniques to determine Cu concentrations in biological fluids and tissues.The distribution of Cu and other trace elements in the liver of LEC rats a strain with a hereditary Cu metabolism disorder following metallothionein MT induction was studied by Suzuki et al. and reported in a number of papers. The protein binding of trace elements was determined by HPLC coupled to ICP-OES detection. Total liver Cu and metallothionein concentrations were determined by ETAAS and RIA respectively. The Cu-MT complexes were found mainly in the cytosolic fraction.The group found that the accumulation of Cu as Cu-MT in the liver of LEC rats eventually exceeded the liver's capacity for MT synthesis. The resulting release of free Cu caused acute hepatitis. The symp- toms of acute jaundice observed in these animals could be eliminated by treatment with tetrathiomolybdate which removed Cu from the liver. Serum Cu and Cu Zn ratios were determined in patients with breast cancer by Yucel et al. using AAS. Both serum Cu levels and Cu Zn ratios were significantly higher in cancer patients compared with control subjects but neither measurement proved to be of value in assessing the activity or severity of the disease. The localization of metallothionein Cu and Zn in the human brain was investigated by Nakajima et al. Metallothionein was measured by RIA and both Cu and Zn by AAS.The concentration of MT in the brain was found to be quite elevated at pg g-'. Levels of Cu and Zn in plasma washed and unwashed erythrocytes and both granulocytes and mono- nuclear cell fractions of diabetic patients were determined by Zeeman-effect ETAAS in a study described by Williams et al. Mononuclear cell Cu was significantly reduced in diabetics to % of normal values but no significant differences were observed for the concentration of Cu in plasma or erythrocytes. The authors concluded that both Cu and Zn status was reduced in diabetes indicating a possible role for these elements in this disease. In an interesting review article Milne discussed the application of various analytical techniques for assessing Cu nutritional status and commented on the fact that non-standardized procedures had hindered the identification of a suitable marker of Cu status.The reviewer considered that the use of a single index was insufficient for adequately assessing total body Cu status and suggested that the measurement of specific activity of Cu enzymes might best reflect metabolically active Cu stores. Romeau-Moreno et al. compared the respiratory toxicity of Cu with ip administration in rats using AAS to determine tissue concen- trations of both Cu and Zn. Similar tissue distributions of Cu and Zn were observed in the rats adminstered Cu by the two routes and significantly higher levels of Cu were found in plasma and liver of both groups compared with controls. Germanium Electrothermal AAS methods for the determination of Ge in biological fluids have been described by four Chinese groups. In the method reported by Guo et al. plasma. ml was diluted + v v with.% Ca-.%Triton X-% HNO,. Samples were ashed at °C and atomized at °C with gas stop. With these analytical conditions an LOD of. ng and a precision better than.% RSD was reported. Chen and Shougui found that chemical modification with a mixture of Sr-NH,NO and STPF con- ditions gave improved sensitivity for the determination of Ge by ETAAS. Blood samples did not require preliminary diges- tion and could be determined directly following dilution. The use of different chemical modifiers both organic and inorganic for the direct determination of Ge in human serum by ETAAS was investigated by Shi et al. and Xu. The simultaneous determination of Ge with As Mo Ni and V in biological CRMs by ICP-MS was performed by Narusawa and Ikuko.Two sample dissolution procedures were compared; the first using HN-HF-H in an open system and the second using HN in a Teflon digestion bomb. The latter procedure was selected for subsequent studies as the risk of element loss and sample contamination were greatly reduced. The Teflon bomb decomposition procedure com- pletely digested all CRMs examined with the exception of pepper bush CRM. This material required the subsequent addition of HF with heating to dissolve siliceous material which unfortunately resulted in a loss of Ge. Gold. The therapeutic use of Au containing drugs as anti-arthritic agents continues to stimulate work on analytical methods for the determination of Au in biological fluids. A comparative study of ICP-MS FAAS and ETAAS for the determination of Au in serum was made by Higasiura et al. Gold was stable for up to d in standard solutions and serum samples diluted in.%Triton X-. moll-' HCl. Good correlation was found between the three techniques. The respective detection limits spanned three orders of magnitude from pg -' for FAAS to. pg -' for ICP-MS. The authors considered that ICP-MS was the preferred technique for analytical sensitivity dynamic range and speed of analysis. An evaluation of different chemical modifiers for the determi- nation of Au in biological fluids by ETAAS was undertaken by Thomaidis et al. Noble metals together with ascorbic acid allowed a maximum pyrolysis temperature of "C to be achieved. Optimum sensitivity was found with STPF conditions and the mixed chemical modifiers Rh-Re Pd-ascorbic acid or Rh-ascorbic acid. With Rh-Re as chemical modifier a detection limit of. pg -' was reported.The addition of NH,SCN to Au standard solutions was necessary to stabilize Au in the presence of the chemical modifiers. An Mo tube atomizer was used by Ohta et al. for the determination of Au in biological materials by ETAAS. Samples were digested with HN,-H,O followed by three cycles of evaporation and re-dissolution with mol -' HC and final dilution with thiocyanate for analysis. Pyrolysis was carried out at "C and atomization at "C. The LOD for the method was. pg of Au and the analytical precision was.% RSD for pg of Au. Indium To improve analytical sensitivity for the determination at the pg - level of In in biological tissues by ETAAS Hardy et al. used a chemical modifier of HfN ,-MgN ,.The modifier was injected into the graphite tube and taken through the drying and ashing stages of the furnace programme prior to sample injection. Biological tissue samples were microwave digested with HN-HS and then treated with H,O for complete oxidation of the organic matrix. Calibration was by standard additions and a detection limit of - ng g-' for tissue and pg -' for plasma were found. Electrothermal AAS with probe atomization was found by Cai and Zhang to be a particularly sensitive technique for the determination of ultra-trace In in human hair. Using peak area measurement calibration was linear from -Opg -' In and analytical recoveries of -% were obtained for spiked hair samples. The authors used the method to determine In levels in human hair samples. Concentrations of In found ranged from - ng -l.The tissue distribution and elimination of In in rats follow- Journal of Analytical Atomic Spectrometry April VoZ. R ing oral and intra-tracheal administration of InP was studied by Zheng et al. Concentrations of In in blood excreta and tissues were determined by ETAAS either directly after acid digestion or following chelation and extraction of In with methyltricaprylammonium. Indium was poorly absorbed in both methods of administration and the absorbed metal was evenly distributed amongst the major organs. Fecal excretion was the main route of In elimination following both oral and intra-tracheal administration. Less than.% of the administered dose was eliminated in urine during a h collection period.The authors concluded that because of the poor absorption of element In was unlikely to accumulate in the body following exposure to InP. Iodine A method for the determination of total I in biological materials of both plant and animal origin using ICP-MS was described by Schramel and Hasse. Solid samples were digested by oxygen combustion and the residue re-dissolved in. mol -' NaOH for determination of I. The method was evaluated by determining I in selected biological CRMs and a LOD of. pg -' was reported. Iron An FAAS method was used by de Sousa et al. to determine the tissue distribution of Fe in P,-microglobulin deficient mice. A progressive Fe overload which resembled that of human haemochromatosis was observed in mice homo- zygous for the mutated P,-M gene. Hepatic Fe concentrations were pg -' in P,-M- -homozygous mice compared with pg g-' in heterozygous P,-M+ -mice. Flame AAS was also the method employed by Millart et al. to determine changes in the levels of Ca Cu Fe K and Mg in rat myocardium following administration of -Fluorouracil. Concentrations of Fe were increased % by -Fluorouracil treatment whereas all other elements showed no change compared with controls.The authors considered that -Fluorouracil cardiotoxicity may be caused by the additional Fe load and associated O consumption producing an increase in -derived free radicals. The effect of long term starvation on tissue deposition of Fe in larval lampreys was studied by Youson who used ICP-OES to determine Fe concentrations in tissues and blood. Starvation led to alterations in both blood and tissue Fe concentrations which the author considered to be due to altered metabolism rather than environmental factors. Lead More than methods for the determination of Pb in blood urine and other biological samples have been described during this review period. Of these the papers considered by this reviewer to be of most interest and importance are those describing new methodological or instrumental approaches examining pre-analytical factors quality of measurement and reference values. Before accurate quantification can be made however samples must be collected with minimum risk of con- tamination from exogenous sources of Pb. Sargent and col- leagues described an easily applied barrier method for the collection of capillary blood specimens for exposure screening programmes.The method employed a thin rub- berized adhesive dressing applied over the ring finger after routine cleaning of the skin surface with alcohol. Capillary specimens were drawn into glass tubes containing heparin anticoagulant. Lead was determined by anodic stripping vol- tammetry. In laboratory trials capillary blood levels collected without the barrier were significantly higher than those with the barrier. Capillary blood Pb levels taken with the barrier were similar to the venous blood levels.The authors stressed however that the method had not yet been evaluated with field trials. Alternative methods of blood collection for mass screening of children were compared by Verebey et al. The authors compared finger stick micro-sample collection into micropipettes and determination by ETAAS with collection onto filter-paper discs and determination by a modified Delves cup procedure. Good analytical agreement was observed between the two procedures for the measurement of Pb in split samples from an urban screening programme. Several factors were found to be critical for obtaining accept- able results by the filter disc method.These were proper cleaning of the finger before sampling the use of characterized 'Pb free' filter-paper use of punched blank discs taken next to the sample and scrupulous cleanliness adopted by the sampling staff. Both ICP-MS and TIMS were used by Dale et al. to investigate the extent of skin absorption of Pb. In controlled laboratory studies a Pb enriched sample was applied to the skin and sweat and urine samples collected. Lead isotope ratios were measured by both techniques to quantitate the absorbed dose. Methods for the determination of Pb in plasma normally employ a pre-concentration procedure to achieve the necessary sensitivity. Bowns and McNutt described an ETV- ICP-MS method for the determination of Pb in plasma at sub-ng g-' levels using isotope dilution with a ,Pb spike for analyte quantification. Plasma was diluted with HNO and p volumes injected onto the wall of the graphite tube. An Ar gas flow of. min-' was found to be optimal for the furnace-dry plasma operation.The authors reported an analy- sis time of. min per sample with a precision of <% RSD and a detection limit of x lo-'' g. Paschal et al. also used ID-ICP-MS with solution nebulization sample introduction to determine Pb in whole blood. Blood samples were spiked with NIST SRM 'O'Pb isotope standard and microwave digested with HNO,.The method was validated by analysis of NIST SRM a and by comparison with a definitive ID-TIMS method. The authors proposed the method be used as a reference method for the determination of Pb in blood in the US blood Pb Laboratory Reference System. A second group Goossens et al. compared different calibration procedures for the accurate quantification of Pb in urine using FI-ICP-MS. The FI system enabled on-line dilution and addition of internal standard and calibration solutions. Optimization of the nebulizer gas flow was essential to achieve maximum sensitivity and precision. Standard additions was found to be the most satisfactory calibration method for accuracy and precision.The authors also observed that with FI the precision of isotope ratio measurements was degraded compared with conventional nebulization. Aggarwal et al. developed an ID-GC-MS method for the quantitative determination of Pb in whole blood and urine. To eliminate memory effects from the chelating agent lithium- bistrifluoroethyl dithiocarbamate the agent was further deriv- atized with -fluorophenyl MgBr to form Pb FCH. Using isotope enrichment with ,Pb good agreement with certified values was achieved for NIST blood and urine SRMs. Application of the coupled technique of GC-AAS for speciation of organolead compounds in biological materials was compre- hensively reviewed by Lobinski et al. The technique of capacitively coupled MIP-AES was used by Wensing et al. for the determination of Pb in whole blood.The sample was vaporized directly from the W filament plasma supporting electrode which acted as the sample holder and which ensured % transfer efficiency of the analyte. Standard additions calibration was necessary as aqueous standards gave poor analytical recovery -Y. Accurate quantification was achieved for Pb at levels above pg -l but values were consistently overestimated at levels of pg -'. An LOD of pg -l was obtained with a pl injection volume. R Journal of Analytical Atomic Spectrometry April Vol. Zhang et al. developed a solid sampling technique for the determination of Pb in powdered biological mater- ials by ETAAS. The analyte was concentrated by pre-ashing at °C for min in a minature sampling cup enabling Pb to be accurately determined at the pg kg-' level. Enhanced analytical sensitivity for the determination of Pb in biological materials by FI-HG-AAS was achieved by Liu et al. with the use of nitroso-R salt in the HG step. Acid digested sample pl volume loop was reacted in the FI system with % nitroso-R-.% NaBH,. With this sample volume a detection limit of pg -' and precision of % RSD for pg - of Pb was found. A small but insignificant interference from SeIV was observed.The growing concern over low-level Pb toxicity in children has led to the establishment of stringent control limits and comprehensive screening programmes in the US. In response to this several groups have developed low-cost or portable systems and micro-sampling methods for the determination of Pb in whole blood. Parsons et al. described a low cost AAS with a W coil filament atomizer operated by a V power supply and Smith-Hieftje background correction. Using peak area integration measurements a precision of -% RSD was found for aqueous Pb standards. Build-up of carbonaceous material on the W filament was recognized by the authors as a significant limitation for blood Pb measure- ments. A portable dedicated single element AAS was con- structed and evaluated by Jones et al. C. Portability was achieved with a novel near-line background correction system in combination with a W filament atomizer and fibre optic cable CCD spectrometer detection. system. With a pl sample volume a detection limit of pg - was obtained. Helfrich and Wingerd C described a rapid method for the determination of Pb in whole blood using an ETAAS 'workstation' dedicated to Pb analysis. Calibration was by aqueous standards prepared by the workstation.The precision for Pb analysis satisfied statutory requirements and a sample throughput of h-' was reported.The groups of Sheier et al. C and Jagner et al. have described methods for the determination of Pb in whole blood which require collection of only microlitre samples. In the first method pl volumes of blood were diluted + v v with an HN,-NH chemical modifier. In the second pl volumes of blood were diluted with pl of H and pl of an HC-Triton X- lOO-Hg"-Bi"' chemical modifier solution. Quantification in both methods was by stripping potentiometry. The method gave comparable results to ICP-MS and ETAAS methods for samples from occupationally exposed and non-exposed individ- uals. Interference effects on the determination of Pb in biologi- cal samples have been investigated by several groups. In the determination of Pb in bone by ETAAS Zhang et al. C reported a background overcorrection error when transverse heating and longitudinal Zeeman background cor- rection was employed with aqueous calibration.The problem was not reproduced with a longitudinally heated furnace and transverse Zeeman correction and could be corrected for in the former instrumental configuration with the use of end- capped graphite tubes. The authors concluded that the overcor- rection arose from molecular absorption by PO the absorption bands of which were also subject to Zeeman effect splitting. Mu demonstrated that matrix interferences on the determination of Pb in urine by ETAAS were markedly reduced by chemical modification with Pd and the use of STPF conditions.To eliminate interferences from high concentrations of Ca K and Na on the determination of Cd Co Ni and Pb in biological samples by AAS Rinkis et al. removed the elements from the interfering matrix by alkali mineraliz- ation and extraction with dithizone in CC,. Studies have been undertaken by various researchers to establish reference Pb levels in blood of both unexposed populations and occupationally exposed groups. A direct micro-sample ETAAS method was described by Wang et al. for the determination of blood Pb levels in healthy Chinese children. Lead levels could be accurately determined with a pl blood sample. The mean blood Pb level was. pmol l-l with a % upper limit of. pmol -l. Al-Saleh et al. examined the relationship between blood Pb and sex age and place of residence in over one thousand Saudi Arabian children. Blood Pb levels increased up to years of age and then declined to a minimum at. Higher blood Pb levels were found in children living in smaller communities than in children living in larger cities.The authors considered that socio-economic status and cultural habits had an important influence on these results. The blood Pb levels of a general Czech population were determined by Syslava et al. C using ETAAS. Only.% of the population had blood Pb levels above pg dl-' indicating a generally low level of environmental exposure. Chlopicka et al. determined Cd and Pb in scalp hair of Polish children by ETAAS with Zeeman effect background correction.The hair concentration of both elements was higher in boys than girls but no correlation between metal concentration and anthropometric factors was observed. The relationship between arterial hypertension and blood Al Pb and V levels was investigated by Granadillo et al. C. The authors described methods for the quantitative determination of the elements in diluted samples using chemical modification with Pd-citric acid-HN,-Triton X-. Both A and Pb were elevated in subjects with essential hypertension compared with normal controls. Lead and Cd contamination in dialysis fluids was determined by Fagioli et al. with Zeeman effect ETAAS. In concentrated dialysis fluids requiring dilution before clinical use Pb was determined at the - pg -' level but no Cd was detected. Romero et al. examined the use of desferrioxamine DFO as a Pb chelating agent in a case of A and Pb intoxication. Concentrations of A and Pb in urine were determined by ETAAS and Ca and Mg levels by FAAS.The authors suggested DFO might be an attractive alternative to EDTA in certain cases requiring Pb chelation therapy. An ICP-MS method was developed by Ghazi to study Pb concentrations and isotope ratios in American human archaeological remains. The Pb isotope ratios of the bones were different and more variable than those determined in local artefacts and pigments suggesting mixing of the Pb from different regional sources. In vivo Pb measurement methods have been reported by Mountford et al. and Todd et al. In the first study tibia Pb was determined by XRF using a bone- seeking Tc radiopharmaceutical excitation source.The pre- sent sensitivity of the system however required a radiation dose too high for routine monitoring of occupationally or environmentally exposed individuals. The second group also used XRF with a Tc internal excitation source to study the kidney concentrations of Pb and Pt in cisplatin treated cancer patients. No evidence of increased kidney Pb at the level of system sensitivity was observed in these patients. An investi- gation of intracellular Pb accumulation was undertaken by Barckhaus et al. The authors used laser-microprobe MS to determine Pb quantitatively in electron dense particles observed in histological sections of kidney and bone. Lithium A comprehensive evaluation of analytical methods for the determination of Li in serum was made by Sampson et al.The analytical performance of five ion-selective electrodes ISEs and a colorimetric method was compared with that of FAAS and FAES reference methods. Precision was Journal of Analytical Atomic Spectrometry April Vol. R better than % for all but one ISE and the colorimetric method. Some ISEs gave reproducibly lower values than the reference methods whilst the colorimetric method gave consist- ently higher values. Interferences from both drugs and inor- ganic ions were observed with both ISE and colorimetric methods. An improvement in the determination of Li in biological fluids by ETAAS was reported by Shalmi et al. who used a Ta-coated pyrolytically coated graphite tube to overcome C- matrix interferences. The method was used to measure endogenous renal tubular fluid:plasma ratios of Li and K in anaesthetized rats.To compare endogenous and exogenous Li clearance in the anaesthetized rat Leyssac and Christensen used both ETAAS and FAES to determine endogenous plasma Li and plasma Li following iv administration of LiCl. No significant difference was observed in plasma Li concentrations determined by the two techniques. An endogenous plasma Li concentration of. pmol l-'. was reported. Administration of Li had an adverse effect on the rate of glomerular filtration and proximal tubular re-absorption. The authors considered that this result indicated that endogenous Li clearance should be used as an alternative to the conventional method for studying renal tubular function. Serum Li levels of bathers regularly using hot spas treated with Li ions were measured by McCarty et al. using ETAAS. An LOD of pg - for the method was reported. No significant difference in serum Li levels was found between bathers regularly using Li-treated baths and control subjects using untreated baths from which the authors concluded that dermal exposure to Li during spa treatment did not result in increased absorption of the element. Magnesium A comparative study of the determination of Mg in plasma by a Methylthymol Blue spectrophotometric method and AAS was made by Saur et al. Plasma Mg values deter- mined by the Methylthymol Blue method were significantly higher than those obtained by AAS and were consistently higher.mmol - I than the normal expected range.-. mmol -' Furthermore the Methylthymol Blue method had poor precision % RSD at normal physiological concentrations. Al-Khamis et al. determined K and Mg concentrations in rat myocardial and skeletal muscle tissue by FAAS.The tissue was homogenized in mmol I-' HCl and the supernatant diluted + v v with H for measure- ment of K and Mg using an air-C,H flame.The concen- trations of Mg determined were different from those obtained with a tissue digestion method. Vieira et al. developed an extraction method using -hydroxyquinoline for the deter- mination of Mg in biological fluids by isotope enrichment TIMS. The total Mg recovered by precipitation with the chelate depended on the matrix although the authors reported that recovery was sufficient for isotope enrichment analysis with Mg. For analysis of Mg in urine a clean-up step with cation exchange resin was required to remove interferents of the thermal ionization process. Many of the studies on Mg in this review period have focused on the role of this element in various medical conditions. Levels of erythrocyte Mg in patients with chronic fatigue syndrome CFS were determined by Hinds et al. using FAAS. Whole blood and plasma samples were diluted v v and v v respectively with.% HNO for quantification of Mg by using aqueous calibration standards and an air-CH flame. No differences in erythrocyte or plasma Mg levels were found between the study group and an age- and sex-matched control group. Six patients were further investigated for Mg deficiency using a Mg loading test. No evidence of Mg deficiency was found.The authors concluded that Mg sup- plementation or therapy was not indicated for this condition.The group of Kisters et al. studied the effect of diuretic treatment on intracellular Mg levels. An AAS method was developed to determine total lymphocyte Mg content. Intracellular Mg concentration was expressed as Mg mmol g-' protein. In patients with essential hypertension intracellular Mg levels were lower than in normotensive control patients xO. versus. mmol g-' protein. In contrast intracellular Mg was elevated in renal hypertensive patients. versus. mmol g-' protein. The group observed that intracellular Mg concentrations in essential hypertensive patients were reduced by thiazide diuretic treatment whereas combined treatment with thiazide and a K-sparing diuretic increased intracellular Mg levels. The group suggested that the combined drug regime was an important means of avoiding intracellular Mg loss during diuretic treatment.The effect of plasma aldosterone concentration on erythrocyte Ca K Mg and Na levels was studied by Saito et al. Electrolyte levels were determined in erythrocyte haemolysates by AAS. Acute changes in plasma aldosterone caused by postural changes were accompanied by an increase in erythrocyte Na and decrease in Mg. Manganese. The apparent renewed interest in Mn observed in the last review has not been sustained through this review period. A simple and rapid method for the determination of Mn in blood and urine was described by Mo in which MgNO was used as chemical modifier. Iwamoto and Nakura used AAS to study the binding of Mn to the D-glucosaminate dehydrogenase enzyme of Pseudomonas Juorescens. The native enzyme contained mol Mn+ per mol of enzyme. Enzyme activity was inhibited by metal chelating agents and restored by addition of Mn in the presence of pyridoxal-'-phosphate.The authors concluded that Mn stabilized the enzyme active site. Mercury As in previous review periods there has been considerable work published on the determination of total Hg and Hg species in biological materials. The effectiveness of mineraliz- ation by conventional convection and microwave heating for the determination of total Hg in body fluids tissues and environmental samples was compared by Tahan et al. No significant difference between the two heating methods was observed and both procedures gave acceptable results for the quantification of Hg in blood urine and sediment CRMs. The microwave digestion procedure however was much faster s than the conventional heating procedure h. Using both mineralization procedures the authors determined the concentration of total Hg in blood and urine from groups of non-occupationally and occupationally exposed individuals. Mean levels of Hg were significantly elevated in both blood. pg - I and urine. pg -l of the exposed group compared with the unexposed group blood. pg -' urine. pg -I. Urinary levels of Hg in a non-occupationally exposed Argentinean population were determined by Roses et al. by CVAAS. Levels of Hg ranged from - pg -'. Concentration of Hg in hair of healthy Japanese individ- uals and a group of subjects suffering from dementia were determined by Nakagawa using an Au amalgam CVAAS method. In healthy subjects males had higher mean hair Hg levels than females. versus. pg -I.The group of dementia sufferers had levels approximately three times higher mean Hg,. pg -I.Two groups described methods for the quantitative determi- nation of total Hg in biological samples by CVAFS. Corns et al. used continuous flow vapour generation coupled to AFS detection for the determination of Hg in urine. R Journal of Analytical Atomic Spectrometry April Vol. The urine matrix was digested with HC and. mol -' KBr-. mol -' KBrO, diluted with H,O and introduced into the continuous flow system where the Hg was reduced with % SnC,. The method was validated by analysis of several urine CRMs. Analytical recoveries were between.% and % and an LOD of ng -' was reported. In the sensitive method described by Winfield et al. biological samples were digested with HN-HS and treated with BrCl to oxidize organic Hg. An aliquot of the digest was reduced with SnCl in a reduction vessel and the released Hg transferred in an He stream to a sample trap containing Au coated sand.The sample trap was placed in a nichrome wire coil and the Hg desorbed at °C onto a second Au trap for quantification of Hg by CVAFS. This two-stage Au trapping system gave a detection limit of pmol -' which the authors considered to be sufficiently sensitive to measure total Hg in blood urine and breast milk of individuals with no environmen- tal exposure. An Au amalgamation trap was also employed by Bergdahl et al. to determine total and inorganic Hg in whole blood by automated CVAAS. For the quantification of total Hg blood samples were digested overnight with HN-HC and diluted with H for analysis. For quanti- fication of inorganic Hg samples were digested overnight with HS and diluted with H,O. Both sample preparations were reduced with % SnC and the Hg purged with Ar to the amalgamation trap manufactured from fine Au wire wound in a loose - cm coil and placed inside a quartz tube. Mercury was rapidly released from the trap by inductive heating of the coil for determination by AAS.The concentration of methyl- mercury in the samples was estimated by subtracting the inorganic Hg value from the total Hg value determined. Limits of detection for whole blood were. pg -' for total Hg and. pg I-' for inorganic Hg. Previously expressed concern of the possible overestimation of inorganic Hg by CVAAS when organic Hg is present was investigated by Lind et al.They found that in brain tissue approximately % of the methylmercury was rapidly demethylated to inorganic Hg in the reaction vessel during the determination of Hg by CVAAS. The magnitude of the measurement error was dependent on the amount of methylmercury and SnCl in the reaction vessel. The authors proposed a correction factor based on their experimental data and empirical data from Hg speciation studies in methylmercury exposed animals. Ma et al. developed an FI-CV-ETAAS coupled technique for the deter- mination of total Hg in both biological and environmental samples. Following digestion the injected sample was reacted with moll-' HC-. % KBH and the released Hg trapped on an Au coated graphite tube at a temperature of -°C. The Hg was desorbed by atomization at -°C. Using standard additions calibration Hg recoveries of -% were obtained for a variety of biological samples and a detection limit of pg was determined. An alternative continuous FI-CV-DCP-AES system was developed by De Andrade and Bueno to determine total Hg levels in human hair. In their system a reversed FI procedure was adopted in which the sample acted as the carrier stream into which the reducing agents were introduced.The reduced Hg was transferred through a PTFE membrane into a twisted Au foil trap in a quartz tube which was in turn connected to the dc discharge plasma chamber. With an injection cycle of s an LOD of. pg was achieved and no memory effects were observed for Hg concentrations up to pg -'. The method was validated by accurate quantification of Hg in NIES human hair CRM. For the speciation of Hg in biological materials by GC-CVAFS Liang et a!. digested tissues in methanolic KOH and converted inorganic and organic Hg species into volatile ethyl derivatives with aqueous C,H ,BNa for separation by GC. Pure standards were used for calibration. Detection limits were. ng g-' for organic Hg and. ng g-' for Hg". Results obtained for the Hg content of various biological materials were in good agreement with measure- ments of total Hg by an acid digestion single stage amalg- amation CVAFS method. For the determination of methylmer- cury and inorganic Hg in fish tissue Gutierrez et al. employed a selective reduction procedure with SnC and SnC,-Cd. Optimum digestion was achieved either by heating at "C or by overnight digestion at - "C. Matrix-matched calibration standards were necessary for accurate quantifi- cation of Hg. Palmisano et al. described an interface design for coupling LC with CVAAS for the determination of Hg species in dolphin liver. Protein bound Hg was released by acid hydrolysis. Inorganic Hg and organic Hg species were determined simultaneously following direct column injection of the liver hydrolyzate and separation of Hg species as cysteinato complexes on a reversed phase LC column.The vesicle mediated HPLC technique previously described by Sanz-Medel et al. for the determination of As species was used by the same group to speciate methylmercury and Hg" in human urine for determination by CVAAS. Good separation of Hg species was achieved with a C, bonded silica column and a mobile phase of didodecyldimethylammonium bromide DDAB in acetate buffer containing % v v CHCN-.% -mercaptoethanol. Detection limits of. pg -'-. pg -' were obtained with off-line pre-concentration of the aqueous samples prior to chromatographic separation. A gas chromatography-MIP-AES method for the determi- nation of organomercury species was developed by Carro- Diaz et al. Chromatographic conditions were optimized to resolve the methylmercury peak from interfer- ing C signals.The accuracy of the method was evaluated by the determination of Hg in DORM- CRM and an LOD of. pg was reported. Despite considerable media coverage during the year of the potential health risks associated with Hg release from dental amalgam fillings only two papers on this topic are reported in this update. Halbach described a method for the quantitative determination of the release of Hg from amalgam fillings following rinsing of the mouth with a polar non-polar solvent mixture. Edible oil and a dilute NaCl solution were recommended as the non-polar and polar solvents. Mercury vapour partitioned into the non-polar phase and ionized Hg partitioned in the polar phase.The Hg content of both phases was quantified by AAS.The same procedure was adopted for determining the quantitative release of Hg from amalgam 'in- vitro'. The author presented equations for calculating the rate of Hg release. Takahashi et al. studied the maternal and foetal distribution of Hg released from amalgam fillings in rats. Mercury concentrations in various organs of the mother and foetus were determined d following implantation of an amalgam filling in the first maxillary molar. In both mother and foetus levels of Hg were highest in the kidney and moderate levels were also determined in spleen liver and lung.These results were contradictory to previous results from the same group and could not be satisfactorily explained. Molybdenum Analytical sensitivity limitations and mutrix interference effects dictate the need for a pre-concentration step for the quantitat- ive determination by ETAAS of Mo in many biological matrices. In the method developed by Chen et al. this procedure was fully automated by coupling FI on-line pre-concentration to ETAAS. Molybdenum was co- precipitated with pyrrolidine dithiocarbamate onto a knotted reactor coil and eluted with pl of IBMK directly into the pyrolytically coated tube of the ETA.The subsequent furnace programme was carried out in parallel with the next Journal of Analytical Atomic Spectrometry April Vol. R pre-concentration cycle. By modifying the FI manifold a -fold enrichment was obtained with a s loading time. These conditions gave an LOD of. pg -' and an analytical precision of % RSD for. pg -'. The Mo concentration determined in a human hair CRM was in good agreement with the certified value. Simple dilution with HzO was the only sample treatment used by Ridao et al. for the determination of Mo on whole bovine blood by ETAAS. Memory effects from residual Mo in the graphite tube were reduced by injecting.% HN between analyses. Good spike recoveries and a precision of - YO RSD were reported. An MgNO ,-Triton X- chemical modifier was used by Pita-Calvo et al. for the direct determination of Mo in human serum by ETAAS.The LOD was. pg -'. The method was used to compare serum Mo levels in healthy individuals and haemodialysis patients. Serum Mo levels in dialysis patients ranged from.-. pg -' compared with values less than pg -' in healthy individuals. The coupled technique of ETV-ICP-MS was found by Schramel and Wendler to be particularly sensitive for the determination of Mo in human serum. A chemical modifier containing mg -' of PdN and mg -' of MgNO was used to stabilize the analyte. The Mo signals at m z and were used for quantification with standard additions calibration. The limit of detection was. pg -'. Gimenez et al. used ICP-OES to study Mo uptake by human erythrocytes. Molybdenum uptake was inhibited by the anion channel blockers DIDS and SITS and also by elevated extracellular concentrations of C- SO,'- and PO'-. Acidification strongly stimulated Mo uptake.The authors hypothesized that the erythrocyte membrane anion carrier catalyses rapid Mo transport and that erythrocytes act as the Mo carrier between the intestine and liver. Nickel An excellent review of methods for the determination of Ni in body fluids by ETAAS was presented by Templeton. The review critically examined preanalytical factors including sample storage and sample preparation as well as analytical methodologies. Vereda and colleagues described a chelation and solvent extraction sample pre-treatment method for the determination of Ni in biological materials by ETAAS and ICP-OES. Nickel was extracted into IBMK by chelation with ,-bis Cphenyl- pyridy methylenel thiocarbohydrazide BPTH and the or- ganic phase analysed directly by either analytical technique.The authors reported a maximum enrichment factor of and a detection limit of. pg I-' for the ICP-OES method. In the ETAAS method described by Sun et al. for the determination of Ni in human serum an unusual mixture of ammonium vanadate mg -' and La. mg -' was used as a chemical modifier. Together with a Mo coated graphite tube the chemical modifier was reported to eliminate all interferences. Serum samples were diluted + with H and protein precipitated with mol -' HWO for analysis. The determination of stable Ni isotopes by ICP-MS in relation to Ni metabolism studies was discussed by two groups. Patriarca et al. C administered a pg kg-' dose of Ni to volunteers and measured Ni and Ni in plasma urine and faeces by ID-ICP-MS with Ni at regular intervals over a d period.To overcome interferences from Ca and Na on the determination of Ni at masses and chelation and solvent extraction of Ni was necessary. Concurrent measurement of Ni and Ni enabled the dietary contribution of Ni to be discriminated from the tracer. Templeton et al. found that principal component analysis was effective in correcting for Ca polyatomic inter- ferences on the determination of Ni in serum digests by ICP-MS allowing accurate determination at levels below pg - '.This approach however was ineffective for urine matrices. Precipitation of urine Ca as calcium oxalate allowed direct determination of Ni in the diluted supernatant. The authors used this method to follow plasma and urine Ni levels in a human volunteer who ingested a single pg kg-' dose of Ni. Plasma Ni peaked at approximately pg -' h after administration. Urinary excretion of Ni indicated absorption of % of the administered dose. Flame AAS is not sufficiently sensitive for the direct determi- nation of Ni in biological fluids and some form of enrichment procedure is required for accurate quantification at pg -' levels. Aydemir and Gucer C described an FAAS method for the determination of Ni in urine using chelation with APDC and extraction with activated carbon for enrichment of the analyte. Calibration was by the method of standard additions and a detection limit of.yg -' was achieved from a starting volume of ml of urine. Unfortunately the requirement for such a large sample volume means this method is not very suitable for routine biological monitoring of occupational or environmental exposure. An investigation of occupational Cd Cr and Ni exposure in dental technicians was undertaken by Min et al. Workplace air concentrations of the metals were monitored by personal samplers. Whole blood concentrations of Cd Cr and Ni were determined by ETAAS following simple dilution with H,O. Blood Ni levels were elevated in dental technicians compared with a control group of office workers and showed a positive correlation with the number of years worked. No significant difference in blood Cr and Cd levels was observed between the two groups. Platinum As in the previous update work covered in this review period is primarily concerned with measurements of Pt in relation to therapeutic drug monitoring. Although ETAAS is not particu- larly sensitive for the determination of Pt it has sufficient sensitivity for monitoring Pt concentrations in body fluids of patients undergoing therapy with Pt-based drugs. Methods for the determination of Pt in serum serum ultrafiltrate and urine by ETAAS were described by Rhorbach et al. An LOD of - pg I-' and precision of -% RSD were reported. Zhang et al. measured carboplatin in human plasma by ETAAS determination of the Pt component of the drug. Calibration was linear up to mg -' and a limit of quantification of. mg -' was achieved. Amorusi et al. also developed an ETAAS method to measure concentrations of another Pt containing drug enloplatin in biological fluids. Plasma plasma ultrafiltrate and whole blood was diluted withTriton X- and an antifoam agent for analysis by ETAAS with Zeeman background correction.The method was suitable for the accurate quantification of Pt over the concentration range.- mg -'.The ETAAS method was used together with an LC method which measured the native drug to study the pharmacokinetics of the drug in humans and animal models. Using ETAAS to determine intracellular concentrations of Pt in EMT KU cellsTakahashi et al. observed that 'in-vitro' uptake of various cisplatin analogues was significantly enhanced by raising the incubation temperature from to °C. The authors considered there was potential clinical application for the concomitant use of Pt drugs and heat. The pharmaco- kinetics and biotransformation of the second generation Pt containing drug Ormaplatin was studied by Petros et al. also using ETAAS to measure ultrafilterable Pt.The pharmacokinetic characteristics resembled those of cisplatin. The half-life of the drug was very short min and approxi- R Journal of Analytical Atomic Spectrometry April Vol. mately % of the drug was excreted in the urine. Electrothermal AAS determination of Pt was also used by Ma et al. to study the 'in-uitro' pharmacodynamic behav- iour of cisplatin. The iv bolus injection and and h infusion routes of cisplatin administration was simulated in cultured human ovarian cancer cells. Levels of bound and unbound drug and drug-DNA adduct formation were determined by ETAAS. Cell survival was determined by a clonogenic assay. No significant differences in the magnitude of the area under the concentration time curve AUC adduct formation time curve or cell survival were found between the different drug regimes.The rate of formation and removal of cisplatin DNA adducts and cisplatin cytotoxicity in cisplatin sensitive and resistant human ovarian cancer cells was studied by Johnson et al. using HPLC and AAS detection of Pt-DNA adducts. Chao also studied the accumulation of Pt and excision of cisplatin-DNA adducts in cervical cancer cells using ELISA and ETAAS methods. The author noted that decreased accumulation of adducts and improved excision repair appeared to be contributory factors to cisplatin resist- ance. Inter-patient variability in the pharmacokinetics of car- boplatin in children was studied by Riccardi et al. who used both ETAAS and HPLC to determine levels of carboplatin in plasma ultrafiltrate. Different doses of carbopla- tin from -mg m-, were administered to a group of child patients as short h or extended up to d infusions and the time course for plasma ultrafiltrate carboplatin appear- ance and disappearance followed by both techniques.This group observed that the administration schedule did not influence drug exposure as similar AUC values were obtained for short or extended infusions of the drug at a dose of mg m-,. To examine the factors affecting kidney Pt concentrations arising from cisplatin treatment Stewart et al. deter- mined Pt concentrations in kidney cortex and medulla autopsy specimens from cisplatin-treated patients by ETAAS. Kidney cortex Pt levels ranged from -. pg -l. Factors that showed a positive correlation with kidney Pt were cisplatin dose and metoclopramide use. A negative relationship between kidney Pt and phenytoin use was also observed.The authors suggested that phenytoin could be examined for its ability to reduce cisplatin nephrotoxicity. Whilst ETAAS is sufficiently sensitive for therapeutic drug monitoring attention has also been paid to ICP-MS in view of its greater sensitivity for the element and its compatibility with a wide range of sample introduction techniques. McKay reviewed the use of ICP-MS coupled with ETV LA and HPLC for the determination of ultra-trace levels of Pt in biological samples. The reviewer concluded that the improved sensitivity afforded by ICP-MS would enable the time course of pharmacokinetic studies to be greatly extended whilst ETV- ICP-MS and HPLC-ICP-MS offered great potential for Pt speciation studies. An ICP-MS method for the determination of Pt in cell suspensions exposed to cisplatin was described by Perry and Balzas. Cells were sonicated acid digested with HNO and diluted for introduction to the nebulizer of the ICP. By eliminating the use of reagents causing inter- ferences on the determination of this element a detection limit better than pg -' was found. Hill and colleagues C described an HPLC-ICP-MS method for the determi- nation of Pt species from new cisplatin analogues. Platinum species were separated on a phenyl-bonded silica RP column with both isocratic and gradient chromatography with an acetonitrile-H,O mobile phase.The eluent was volatilized after pneumatic nebulization in a heated spray chamber and desolvated with a membrane drier tube and cryogenic con- denser before introduction into the plasma.The build-up of carbon on the cones was prevented by the addition of O to the nebulizer gas. Rare Earths. The techniques of NAA HPLC with post-column reaction and ICP-MS were compared by Chiba et al. for the determination of REEs in biological tissues. Mice were injected iv with one element from the RE group at a dose of mg kg-l and after h the element concentration in vari- ous organs was determined by the three analytical techniques. The liver lungs and spleen contained almost % of the total amount of element administered. The same group also examined the eflect of administration of RE elements on the organ concentrations of essential elements following iv injection of a mixture of REEs at a total dose of mg kg- '. Organ tissues were digested by wet ashing and REEs deter- mined by ICP-MS or HPLC-post-column reaction. Essential elements were determined by AAS colorimetry or MIP-MS. Concentrations of REEs were highest in lung spleen liver and kidney. Administration of the cocktail produced markedly elevated concentrations of Ca in all the above organs and elevated levels of liver Fe K Mg P and Zn. Decreased liver mass and increased plasma aspartate transferase activity were also observed.The determination of MT bound Zn by AAS together with UV and ELISA analysis of MT were used by Xiao et al. to examine the induction of liver MT synthesis in rabbits injected with REEs. Metallothionein synthesis was only induced at high doses - ppm of REEs. Ruthenium Formento et al. described a rapid method for the determination of Ru in biological tissues and fluids by ETAAS. Homogenized tissue samples were digested with HN-H in a microwave oven and the digest analysed directly by ETAAS with D background correction. Serum samples were simply diluted with. YoTritonX-. YO HNO,. Analytical precision was better than % RSD and limits of quantification were ng g-' for tissue samples and pg - for serum. Selenium. There is again a wealth of articles on the determination of Se in biological materials this review period. A number of groups have described methods employing HPLC coupled to spectro- scopic detection for the speciation of Se in biological samples. To investigate the effect of the dietary source of Se on its metabolism Crews et al. C developed an HPLC- ICP-MS method. With an ion-exchange chromatography column and salicylate buffer Se-methionine Se-cysteine Na-selenite and Na-selenate were adequately separated and Se accurately quantified by isotope ratio measurements. Pitts and colleagues described a method which employed HPLC coupled to on-line microwave digestion and detection by AFS for the determination of Se in aqueous media. By introducing the HPLC step the method overcame the earlier problem of indirect determination of SeV by difference when using an HG technique. An HPLC-ETAAS coupled method was developed by Potin-Gautier et al. for the deter- mination of selenoaminoacids. With a laboratory designed interface and a p sample loop LODs of pg -' for Se-methionine and pg -' for Se-cysteine were achieved.The method was used to determine Se aminoacids in white clover CRM certified for total Se. Suzuki et al. also described an HPLC-ICP-MS coupled technique to speci- ate Se in biological samples.The Se species were separated by size-exclusion chromatography and Se measured at m z and. The authors found that diets with different Se contents markedly altered the distribution of Se species in liver kidney and urine but less so in blood samples. Factors affecting the precision of Se-Se isotope ratio measurements by N Journal of Analytical Atomic Spectrometry April Vol. R MIP-MS were investigated by Yoshinaga et al. Precision could be improved below.% RSD by increasing the integration time. An interference from SO,- at mlz was observed but did not severely affect the accurate quantifi- cation of Se in biological samples.Takano et al. evaluated the performance of two methods for the separation and pre-concentration of trimethylselonium in urine for deter- mination by ETAAS. An ion-pair extraction method with Na tetrakis-fluoropheny borate complexation and extraction with dichloroethane gave similar analytical sensitivity as com- plexation with the same chelating agent and adsorption onto a cellulose nitrate filter. However better analytical precision was obtained with the cellulose filter method. An LOD of pg I-' Se was reported for both pre-concentration procedures. Flow injection methods have also been described for the quantification of total Se in biological materials. Sundin et al. C C used a HBr-Br reagent to digest sel- enium metabolites into a form suitable for HG analysis.The SeH was subsequently trapped in a graphite furnace for determination by ETAAS. Factors affecting the trapping of SeH were investigated. The method was validated by accurate determination of Se in NIST urine SRM. Li et al. used an FI-HGAAS method to determine total Se in blood samples from Chinese subjects. The range of Se values determined was - pg l-l and an LOD of. pg -l was reported. A simple decomposition procedure for the determination of Se in blood and urine by HGAAS was described by Tiran et al. Samples were digested at "C with HS,-H,O,. A good agreement was found for the determination of Se in blood and urine by this method and the IUPAC digestion procedure with HNO,-HSO-HCIO. The method was used to determine Se in whole blood and serum of healthy Austrian children aged between and years. Low Se levels found in year old children rose signifi- cantly at years and then stabilized.The Se levels determined however were amongst the lowest reported for European inhabitants. Lillemoen and Hassett C also described an acid digestion method for the determination of Se in biological samples. Samples were digested with HC in closed vessels to avoid loss of Se as the volatile chloride. With this closed system samples could be heated for up to hours without loss of analyte. Harrison et al. developed a microwave digestion procedure for the determination of total Se in hair and nail samples. Samples were digested with HN-H and Se determined by ETAAS using Pd chemical modification. An LOD of. pg -l for both matrices was found. Results for the determination of Se in hair by the method were in good agreement with NAA results. When using the method analysis of hair samples gave a range of values between. and. pg g-' of Se. A number of researchers have examined the use of chemical modifiers for the quantitative determination of Se in biological materials by ETAAS. Johannessen et al. compared the efficacy of previously recommended CUNO ~ MgN , NiN and PdN chemical modifiers for the thermal stabilization of different Se species. A Pd-Mg chemical modifier stabilized selenite selenate and Se-methionine but gave only % of the anticipated sensitivity for trimethylselon- ium.This modifier was used for the determination of Se in serum and NIST freeze-dried urine SRM. Deaker and Maher also examined the efficacy of CUNO ~ NiN and PdN and combinations of these chemicals with Mg NO as chemical modifiers for the determination of Se by ETAAS.The authors found that optimum signal response for Se in digested biological samples was obtained with a modifier containing. pmol Pd-. pmol Mg. For the deter- mination of total Se in urine by ETAAS Drake et al. found that a Pd-Mg-Ba chemical modifier gave satisfactory results for the analysis of urine SRM. With this chemical modifier cocktail a detection limit of pg - was achieved. A Cu-Ni chemical modifier was used by Li et al. for the determination of Se in serum by ETAAS. Rock and Booth C found that a Pd-hydroxylamine HC chemical modifier overcame the problem of precipitation of Pd and coagulation of clinical specimens that occur when ascorbic acid is used as the reducing agent in combination with Pd for Se determination by ETAAS. Burrini et a!. however used a Pd-citric acid-Triton X- chemical modifier to determine normal levels of serum Se in the Italian popu- lation. An NiNO chemical modifier was used by Lin et al. to determine Se in Chinese proprietary medicines by ETAAS following sample digestion with HNO,. Shrader C described the use of new instrumentation design for the determination of Se in biological samples by Zeeman effect ETAAS.The use of boosted EDLs and a different photomultiplier design giving superior response in the UV region of the spectrum increased the intensity of the light source and lowered noise levels to improve both sensitivity and precision. Ni et al. C examined the use of an Ag-modified graphite tube for the determination of Se andTe in urine by ETAAS. Their method involved in situ concen- tration of Se and Te by trapping the hydrides on the Ag-modified tube. The Ag tube trap was shown to be an adequate alternative to chemical modification with Pd for determination of Se in biological samples with Se concen- trations greater than ng g-'. Several studies have reported ranges of Se concentrations in biological fluids in both healthy populations and subjects with various pathological conditions. Alaejos and Romero comprehensively reviewed analytical data on Se concentrations in human urine published between and. The reviewers considered that urine Se may be a more suitable indicator of Se status than blood Se levels in view of the fact that it appears to respond more quickly to changes in dietary intake. Selenium levels in serum from healthy individuals in different regions of the Czech Republic were determined by Korunova and Selecka C using ETAAS with Zeeman effect background correction and a Pd-citric acid or Pd-Mg chemical modifier. Improved sensitivity was observed with the first modifier. Samples were simply diluted with the modifier solution prior to determination. Average Se levels were pg l-l with a range of.-. pg -'. Whole blood and serum Se levels in patients with epidemical neuritis were determined by Prieto et al. using ETAAS with D background correction.Two sample pre-treatments were examined. For serum determinations samples were diluted with a Ni-Triton X- chemical modifier whilst whole blood was diluted with H and a Pt-Ni chemical modifier injected separately. Statistically different Se levels were found in patients serum Se= pg l-' blood Se= pg -l compared with controls serum Se= pg l-' blood Se= pg -l.The relationship between hair Ca and Se nutritional status was investigated by MacPherson and Balint. Plasma Se was determined by HGAAS. The authors observed that a large proportion of the study group % had plasma Se levels below pg -l and % had levels less than pg l-' providing further evidence of inadequate Se in the Scottish diet. Recent interest in SIDS has focused on the possible role of Se in this syndrome. Lemke et al. investigated the possible role of Se in the etiology of this syndrome hypoth- esising that a Se deficiency may cause an immunosuppression. Serum Se was determined by AAS. The authors found no evidence of a Se deficiency in SID victims.The Se status of patients receiving long-term parenteral nutrition was investi- gated by Yamamoto et al. using HGAAS. Plasma Se levels of subjects receiving parenteral nutrition without Se supplementation were lower than control subjects but were returned to normal values by supplementation with - pg R Journal of Analytical Atomic Spectrometry April Vol. of Se per day. Paszkowski et al. used ETAAS to determine Se concentrations in serum and follicular fluid in a study to evaluate the Se status of 'in-nitro' fertilization patients. Patients with unexplained infertility had significantly reduced follicular Se levels compared with subjects with tuba infertility. The activity of the Se enzyme glutathione peroxidase was also diminished in follicles with non-fertilized oocytes. Silicon A method for the direct determination of Si in whole blood by ETAAS was described by Lin et al. Interferences from the blood matrix were minimized by the use of a Ca chemical modifier and W coated graphite tube. Matrix-matched calibration was necessary for accurate quantification of Si. Bercowy and Rieders described a DCP-AES method for the determination of total Si in biological fluids. A linear range of - mg -' of Si and an LOD of. mg -' for plasma whole blood and urine were reported. Levels of Si determined in a normal population by the method were <.- mg -' for blood matrices and.- mg -' for urine. Over % of blood samples analysed had Si levels less than. mg -'. Silver.The sensitivity of FAAS for the determination of many elements is significantly improved by atom trapping in a quartz tube.This approach was adopted by Huang et al. for the determination of Ag in oyster tissue CRM. The effect of burner height gas flows flame composition and trapping time on the sensitivity of the method were investigated. Five hundred milligram samples of oyster tissue CRM were digested with ml HN-ml HClO and diluted to ml with H for Ag determination. The best sensitivity was achieved using an air-CH flame with an air flow rate of h-' and CH flow of. min-' for trapping and. min-l for release. A trapping time of min gave a -fold improvement in sensi- tivity over conventional FAAS. Precision was better than % RSD for an Ag concentration of. pg g-'. Tsipouras and colleagues developed a chemical model system to study the solubility of Ag from silver sulfadiaz- ine in various physiological solutions in order to gain a better understanding of the mechanisms of absorption of Ag following silver sulfadiazine treatment of burn wounds. Silver sulfadiazine lmg was incubated with ml of test media over weeks after which the solution was filtered.The filtrate was analysed for Ag content by both FAAS and ETAAS with Zeeman effect background correction. Various media including a synthetic electrolyte solution containing individual endogen- ous ligands cysteine histidine glutathione beef blood protein solution and human serum were examined for their ability to solubilize Ag. A. mol -' solution of NaNO was used as a control non-interactive solution. Dissociation of silver sulfadi- azine and solubilization of Ag was greatly enhanced by the presence of C- peptides and proteins.The authors considered there was the potential for significant Ag absorption in the early stages of burn treatment with this compound particularly if a large body surface was affected. Sodium and potassium. The simultaneous determination of concentrations of K and Na inside single human erythrocytes by pulsed laser vaporiz- ation ICP-OES was described by Cheung et al. With a modified sheath gas flow arrangement it was possible to detect. fmol of Na by measuring the atomic emission from one laser pulse. Poisson statistics were used to determine single-cell concentrations from vaporization of multiple cells by a single laser pulse. The intracellular concentrations of K and Na varied significantly within cells of one individual f% for Na and f % for K and the variability was not explained by cell volume changes.The authors concluded that the results reflected the age distribution of erythrocytes in the sample. Levels of K in bone of residents of Beijing were determined by Lin using AAS. The K levels were log normally distributed with a range of.-. g kg-' bone ash. Highest concentrations of bone K mean value.g kg-' were observed in young infants < year and the lowest levels. g kg-' in children aged - years. Strontium Previously published studies have reported widely variable values for the concentration of Sr in tooth enamel from to ppm. Suzuki and colleagues considered that interferences from other inorganic ions in the determination of Sr by AAS was an important contributory factor to the variability of these values.They noted that FAES with a N-CH flame was much more sensitive than FAAS for the determination of this element and described a method for the quantitative determination of Sr in mg samples of human teeth. A ppm K solution was added to digested tooth enamel to overcome interferences. With this method an Sr concentration of pg -' was determined in human molar tooth enamel. Desmet et al. used ICP-OES to deter- mine Sr in human whole blood following microwave digestion of the blood samples. The method gave an LOD of. pg l-' and a mean value of. pg -l was reported for normal whole blood. The method was used to investigate the enhancement of blood Sr in cases of drowning. Tellurium. The Te" selective chelating agent Bis-IIS a bismuthiol-I sulfonic acid derivative coupled to an ion-exchange resin was used to pre-concentrateTe from urine for determination by ETAAS in a method described by Chikuma et al. Urine samples were digested with HNO,-HClO,. TelluriumV in the digested sample was reduced to Te" by boiling with mol -' HC and Bis-IIS resin added to the solution to complex Te. The resin suspension was mixed with NiN as chemical modifier for determination by ETAAS. Recovery of Te from urines spiked at - pg I-' ranged from to %. In order to monitor patients administered a novel an ti- tumour drug ammonium trichloro dioxoethylene- U tellurateIV Aggarwal et al. developed an ID-GC-MS method for the determination of Te in urine. Samples were digested with HN,-H and derivatized with lithium bis trifluoroethyldithiocarbamate. The Te derivative was reacted with Grignard reagent for GC-MS analysis. All five majorTe isotopes were measured using "OTe as an internal standard. No carryover or memory effects were observed and Te concentrations in the - pg I-' range were determined with an RSD of -%. The GC-MS method was validated by comparison with an ETAAS method. Tin. The use of various chemical modifiers for the quantitative determination of Sn in whole human blood was investigated by Chiba et al. The chemical modifiers mg -' Ni,.% H,PO and % ascorbic acid all gave improved analytical sensitivity for the analyte. A detection limit of. pg l-' for a p injected sample was found. The method was used to determine the blood Sn levels in a group of Sn smelters. The levels found ranged from <.- pg -'. The same group described AAS INAA and RNAA methods for the determination of Sn in biological CRMs and human liver samples. For AAS determination samples were acid digested and Sn was extracted into IBMK. Good agreement in the value determined for Sn was observed between the techniques Journal of Analytical Atomic Spectrometry April Vol. R and with the reference values. Levels of Sn determined in the.Thorium and Uranium liver samples ranged from.-. pg g-' wet mass. A further chemical modifier KNO, was employed by Lin et al. for the determination of Sn in whole blood by ETAAS. As in previous reviews much of the work has focused on the determination of both inorganic and organotin species. Both inorganic Sn and tributyltin species in biological samples were determined by ETAAS in the method described by Pang et al. For total Sn determination samples were acid digested and the digest solution passed through an anion- exchange column to remove dissolved solids and interfering lipid residues prior to determination by ETAAS. For quantifi- cation of tributyltin species the acid digest was extracted with pentane and inorganic Sn dibutyl Sn and monobutyl Sn removed by back extraction into. moll-' NaOH.Tributyltin was adsorbed onto a C solid-phase extraction tube and eluted with CH,OH-HNO for quantification of Sn by ETAAS using a tungsten-coated tube. Other groups have described methods for the determination of organotin species. Ku balla et al. described a coupled GC-AAS method for the determination of organotin species in water soil sediment and fish tissues. Samples were treated with hexane and sodium tetraethylborate as an 'in-situ' ethylating agent and the organic layer injected directly onto a DB GC column. A heated quartz tube atomizer was used for AAS determinations.The authors applied the method to study the contamination of the Elbe river with inorganic tin and organotin compounds derived from docking activities in Hamburg harbour and run off from an Sn smelter. Ceulemans et al. described a simplified sample preparation technique for the GC analysis of organotin species in marine biological samples. Sample dissolution with tetramethlyammonium hydroxide TMAH and enzymic hydrolysis were compared with conventional acid digestion. In situ ethylation with sodium tetraethylborate was performed without any separation of the analyte from the sample matrix. The capillary GC was coupled to MIP-AES for the determination of Sn.The methods were validated by quantitative analysis of fish CRM NIES-. The process of sample preparation for GC-HGAAS was fully automated in the method described by Bautista and Altenau C for the determination of organotin compounds in biological samples. The modification of a commercial vial sampler and purge and trap headspace concentrator eliminated the need for manual derivatization of samples prior to analysis thereby greatly improving precision and sample throughput. The appli- cation of He MIP-AES for the determination of organotin compounds in biological samples was described by Sumki et al. Organotin compounds were extracted from homogenized samples with acidified diethyl ether and alkylated with methylmagnesium bromide. The alkyltin compounds were separated by GC and quantified by MIP-AES detection. Limits of detection for organotin compounds ranged from.-. pg and the values determined in several tissue homo- genates agreed we with those obtained by GC-MS with selected ion monitoring.Titanium For the determination of Ti in human serum by ETAAS with Zeeman effect background correction Skipor et a!. found that even dispersion of the sample in the graphite tube was critical for reproducible results. To achieve this dispersion a lengthy temperature programme was employed to prevent spattering of the sample and excessive build-up of carbon residue. Samples were diluted + + v v with.% HNO and.% Triton X-. With this pretreatment the detection limit was. pg - '.Twiss and Watling described an ICP-MS method for the determination ofTh and U in faeces which was used to monitor workers occupationally exposed to the elements. A precision of % RSD was satisfactory for routine analysis and detection limits of ng g-' Th and ng g-' U were reported. An accumulation of both Th and U in faeces together with an increase in the ratio of Th to U was observed in workers occupationally exposed to monazite ore. Vanadium Yaman and Guecer described an FAAS method for the determination of V in biological matrices including animal tissues and urine. Enrichment of V from the sample matrix by chelation with -hydroxyquinoline and adsorption of the che- late onto activated charcoal was performed to achieve the necessary sensitivity for accurate quantitation of V in these matrices. Zinc. The effects of sample matrix on the determination of Zn in rat liver by FAAS was examined in detail by Luterotti. Synthetic samples simulating diluted liver homogenates were prepared in three homogenization media; H,OTRIS-acetate buffer and mol -' HCl. They were spiked with Zn at concentrations between. and. pg -' to produce matrix- matched calibration standards. The influence of matrix effects was evaluated from the observed changes in calibration sensi- tivity. The HC medium was found to be least affected by matrix components. Using this medium accurate quantifi- cation of Zn in complex matrices was also achieved with aqueous standards thereby eliminating the need for matrix matched calibration. Two groups have reported methods for the quantitative determination of Zn in leukocytes. Tsunoda et al. separated leukocytes from whole blood by dextran centrifugation and disrupted the cells by ultra- sonication. Zinc was determined by FAAS. Leukocyte levels were determined in healthy adults and the mean Zn content was. pg -' protein pg per " cells. No sex-related difference in leukocyte Zn was observed. Leukocyte Zn was also determined by Lei et al. using FAAS. A method for the determination of serum Zn both bound and unbound by pulse sampling FAAS was developed by Shi et al. For the determination of total Zn serum was diluted + v v with H,O.To determine bound Zn serum was diluted I + v v with saturated NH ,SO and centrifuged. The precipitate was re-dissolved in H,O and a pl aliquot taken for determination of Zn by FAAS with Zeeman effect back- ground correction. The serum Zn level in healthy Chinese children aged between and years was determined by Zhu and colleagues using FAAS. Serum Zn levels were higher in girls and increased with age.The authors considered that children with a serum Zn level <. mg -' were Zn deficient and should receive Zn supplementation for satisfac- tory growth. The variability in the measurement of plasma Zn levels of men and women in the age range - years was investigated by Smiciklas-Wright et al. Repeated blood samples were taken by finger prick on five occasions over a d period. Plasma Zn was determined by FAAS using a micro-injection method. The day to day inter-individual variability was about %. The variability was not attributable to dietary Zn intake or changes in serum albumin concen- tration. The authors concluded that estimations of Zn status in older populations could not be accurately made from a single blood sample.The rate of disappearance of plasma Zn following a single injection of Zn was studied by Yokoi et al. using ICP-MS to determine Zn:Zn ratios. Blood samples were collected at regular intervals following an fR Journal of Analytical Atomic Spectrometry April Vol. iv injection of mg of Zn. Plasma was digested with H and the Zn extracted with.% diethlyammonium dithio- carbamate into CCl and back-extracted into HN for deter- mination of Zn. In this review period groups have investigated the Zn status of haemodialysis patients children with asthma and individuals shortly following acute myocardial infarction. The Zn status of uraemic patients with or without haemodialysis treatment was investigated by Cheng et al. who determined serum Zn levels by FAAS. Mean serum Zn levels were lower pg - I in patients not undergoing haemodialysis corn- pared with dialysis patients pg -' and both groups had significantly lower serum Zn levels than controls pg -I.The authors considered that inadequate Zn from a restricted protein diet was a contributory factor to the observed Zn deficiency. The concentrations of Zn in serum blood and ultrafiltrate from patients undergoing haemodialysis was deter- mined by Jimenez de Blas et al. using both FAAS and ETAAS. Blood was digested with HN,-HS followed by heating with H and dilution with H. Serum was similarly digested omitting the H treatment. Both digests were analysed by FAAS. Ultrafiltrate was diluted v v for direct determination of Zn by ETAAS. Arnaud et al. studied changes in serum Zn levels and Zn distribution in a group of patients over a d period following acute myocardial infarction using ultra-filtration and ETAAS to determine total serum and exchangeable Zn. Serum Zn levels declined over the first d following infarction but then returned to normal values.The decline in serum Zn was entirely attributable to changes in the exchangeable fraction. Malvy et al. examined the trace element status of children with inflamma- tory asthma. Plasma Zn was determined by FAAS and plasma Se by ETAAS. Both plasma Zn and Se levels were significantly decreased in children with asthma. pmol -' Zn,. pmol -' Se compared with controls. pmol -' Zn,. pmol -' Se. Powell et al. investigated the cardiac protective properties of Zn in post ischaemic isolated rat heart. Pre- and post-ischaemic treatment with Zn resulted in a Zn concen- tration dependent enhancement of post-ischemic cardiac func- tion. Analysis of heart tissue by AAS showed that hearts treated with Zn had % less Cu than control hearts.The authors concluded that the cytoprotective action of Zn was associated with the interaction between tissue Zn and Cu. Conclusions Continuing progress has been made in the application of on-line digestion reaction and preconcentration or separation for the presentation of samples for analysis by AAS and ICP- AES Section. It has been taken to its ultimate conclusion by Burguera et al. in a continuous FI system from the patient's forearm to the spectrometer for determination of Co in blood by ETAAS. An important new development has been brought about by the requirement for mass screening of children for lead exposure in the USA see Section. For this simplified dedicated analysers for measuring Pb in blood by ETAAS were devel- oped. Some workers aimed at portability to allow measure- ments directly in a clinic. As some of these developments could have important 'knock-on' effects for ETAAS generally further details of these developments are awaited with interest. Applications of accelerator mass spectrometry have shown an increase.There has been a growth in the number of tracer studies using A and an emergence of interest in studies on Ca using the isotope ,'Ca. One wonders about the cost benefit ratio of these studies when often the number of collaborators exceeds the number of subjects studied. Although it is import- ant that AMS offers the possibility of tracer studies on A with a non-radioactive isotope it is disappointing to find consider- able differences reported on the percentage of A absorbed. In addition the finding of Jouhanneau et al. that citrate does not increase the absorption of Al seems in contradiction to previous studies e.g. Slanina P. et al. Food Chem.Toxicol.,. An exciting new approach is that of Nomizu et al. for measuring element concentrations in individual blood cells by ICP-AES. Cells were suspended and diluted sufficiently for each nebulizer droplet to contain at most one cell. Pulses of emitted light were then detected and passed to a multi-channel pulse height analyser. Success was only possible at the time of reporting with Ca as the sensitivity was inadequate for other elements.The approach clearly has potential and we look forward to reporting details of their promised further work on use of alternative droplet generators and use of ICP-MS. Table. The 'Multi-element' section which presents papers where five or more various elements are included has been arranged so that similar applications appear together. Entries have been grouped as Serum plasma blood; Urine; Other biological fluids; Soft tissues; Bone and other hard tissues; Hair nails; Biological materials RMs CLINICAL AND BIOLOGICAL MATERIALS. Element Matrix Technique; atomization; Sample treatment comments Reference Biological tissues Sulfadiazine complexes AA;ETA;L AA;F;L Ag Lobster digestive gland AA;F;L Binding of Ag Cd Cu and Zn to medium and high f A A; ETA; L relative molecular mass components was investigated.Tissue homogenized in mol -' CH,COONH at pH. was centrifuged and filtered. Sephadex gel chromatography of the filtrate with mol -' CH,COONH at pH. separated the species for measurement of Ag by ETAAS and Cd Cu and Zn by FAAS Tissues were solubilized in HNO,; HC was added and heated and the solution diluted with H. The instrumental parameters were optimized for atom- trapping and with min sampling an enhancement of -fold was reported in Chinese Interactions between silver-containing ointments and media such as NaC glutathione and serum were investigated. The ointment was suspended in a solution of the test medium for weeks and then filtered through a. pm Teflon membrane. Ag was measured in the filtrate AA;F air-C,H,;L Journal of Analytical Atomic Spectrometry April Vol. R Table continued Reference CTechnique; atomization; Element Matrix A Pharmaceutical solutions AE;ICP;L Sample treatment comments suitable sensitivity was found at and nm. Interferences from Fe and C were observed at nm while Ca gave strong emission close to Higher tissue A concentrations were found when rats were given fluids stored in A cans compared with glass bottles Triton X-. An LOD of pg -' was reported in Spanish A transversely heated graphite atomizer was compared with a conventional system. Comparable results were obtained but a lower optimal atomization temperature "C shorter analysis times and less carryover were evident with the newer instrument Positive influences of NH,H,PO, MgCl and CaCO and negative effects of HC on the atomization of A were demonstrated. Dissolved solids also influenced the signal and only standard additions calibration gave accurate measurements Analysis of RMs showed that the assay was accurate and precise. Concentrations were increased in samples from subjects with hypertension and chronic renal failure Human urine was diluted :l with. mol I-' HNO, taken to "C and allowed to cool to room temperature. Rat urine samples were diluted with % H and mol -' HNO, l:l:l heated at "C for h rediluted and re-incubated.This treatment redissolved urinary precipitates evaporated almost to dryness. H was added with heating and H added to ml. The A was determined by AES at. nm and the LOD was. pg ml - ' in Chinese sample containing up to pg added to silica gel or Chrome Azurol S-modified Amberlite IRA columns.The A was eluted with mol -' HCl and enrichment factors of up to -fold were achieved without interference from Ca Cu Mg Na or Zn. The Amberlite column could not be used with Fe-rich samples HPLC coupled to ETAAS was used to separate and identify proteins binding A and Fe. The AAS conditions were adjusted to permit measurement of A and Fe in the eluate buffer. All solutions were passed through a silica-based 'scavenger' to remove traces of these metals before they were used citrate was measured in rats. The A was measured by AMS AMS was used to show the distribution of A among cellular compartments and culture medium in cultured human neuroblastoma cells Careful optimization of sheath gas viewing height wavelength background correction and sample diluent was described. With appropriate conditions the LOD for diluted samples was. pg -' Samples were diluted ten-fold in H with Y as an internal standardTissues were ashed and % m v PTFE slurry added. The suspension was homogenized by ultrasonication for min and a portion taken for electrothermal vaporization into the plasma. With the PTFE modifier which served as a fluorinating agent dissolved salts did not interfere with the determination and the LOD was pg Electrothermal vaporization of A into the plasma was improved by inclusion of a PTFE slurry in Chinese Different emission lines were investigated and Plasma specimens were diluted + with. YO ml urine and ml HNO were heated and. The pH was adjusted to with Tris buffer and Gastrointestinal absorption of A with or without A A A Tissues Plasma Plasma urine AA;ETA;L A A;ETA; L A A;ETA;L A Urine AA;ETA;L A A Plasma Urine AA;ETA;L AE;ICP;L A Urine AE;F N,O-C,H,;L AA;F N,O-C,H,;L A Dialysis solutions A Plasma proteins AA;ETA;L Plasma urine liver bone Neuroblastoma cells Biological samples A A A MS;ICP;L AE;ICP;Sl A A Serum Serum tissues AE;ICP;Sl A Serum R Journal of Analytical Atomic Spectrometry April Vol. Table continued Element MatrixTechnique; atomization; Sample treatment comments A A A A A A A A Brain liver Serum urine Tissues Biological materials Tissues Dialysis fluids water Serum urine tissues Dialysis fluids MS;-;S MS;-;S MS;-;S AE;ICP;L AA;ETA;L.___ AE;ICP;L AA;ETA;L A Serum dialysis fluid water AE;ICP;L Samples were diluted + with H and the A measured at nm. Careful background correction was necessary for serum specimens and a Y internal standard at a final concentration of pg -' was included in the diluent.This permitted compensation for matrix effects. The procedure was demonstrated to be rapid and robust digestion with HN,-HClO the residue was dissolved in H with Al carrier. A was precipitated as the -hydroxyquinoline complex by addition of ammonium acetate. The precipitate was collected and ashed at "C to form Al, which was compressed into the sputter cathodes for measurement of A by AMS A was measured by AMS in samples from two volunteers who consumed test doses of A. Intestinal absorption and urinary excretion were calculated and a compartmental model for aluminium metabolism was proposed experiments to determine disposition after intravenous administration Sample mg was digested in. ml HNO,,. ml % H and p HF with microwave heating.The digest was diluted to ml with B solution Concentrations in tumours were compared with levels in healthy tissues Data from an external quality assessment scheme were reviewed. Performance of the laboratories improved between and but was considered poor for some participants After dilution + in g -' KCl the samples were nebulized into an Ar plasma and A emission was measured at. nm with an LOD of. pmol -'. The KCl prevented interference from Ca in French A in the sample was complexed with. mol I-' Tiron ,-dihydroxy- ,-benzenedisulfonic acid at pH. The complex was adsorbed on an AG MP- resin column and eluted with. mol -' HCl. The Tiron was desorbed with mol -' HCl for further use of the column and the entire procedure was accomplished within an FI manifold Chromotrope B immobilized on AG -X. Features involved with retention and elution were investigated.The LODs were and. ng ml-' with FAAS and ICP-MS respectively ref. exchange column Protein-Pak DEAE-PW. The eluted fractions were taken for measurement of A and Si A systematic study of diluents and chemical modifiers was reported. Ca NO was recommended for use with digested bone samples and CaNO in.% HN was preferred for sera Liquid specimens were analysed untreated; tissues were solubilized with HNO,. The LOD was given as pg -'. Toxicity in joints was reported after injection of A ingestion of breast milk or special formula feeds. Concentrations were significantly increased in babies fed high-A milks compared with breast milk Samples were diluted -fold with.% v vTriton X-. Concentrations were increased in patients with essential hypertension Samples were collected from animals given A. After A was measured by AMS in tissues from rats in. The A was concentrated on-line by retention with This work is described in more detail in Various Speciation was achieved on a polymeric anion- A was measured in samples from infants after A Dialysis fluids MS;ICP;L AA;F;L A Stomach intestine MS;ICP;L A Serum A A;ETA; L A Serum bone AA;ETA;L A Plasma urine tissues AE;ICP;L A Plasma A Plasma AA;ETA;L AA;ETA;L Journal o Anal tical Atomic S ectrometr A ril Vol. Reference R analyte form * AA;ETA;S Element Matrix As Hair Sample treatment comments Reference mm segments of hair were placed into a cup-in- tube device with pl chemical modifier [ pg Pd+ pg MgNO ,].The LOD was. pg g-' Optimal pH for generation of ASH was found to vary for different As species. Addition of % cysteine gave the organosulfur derivatives which were found to react similarly with tetrahydroborate in an FI-HG system. not associated with C- species but are caused by signal enhancement caused by a C matrix. Accurate results were obtained with matrix matched calibration ,-Cysteine was used to reduce As species to As"'. Acid conditions for HG in an FI system were achieved with HNO,. This arrangement reduced interference from C- Samples were diluted :. Cl was used to correct for the ,'ArW interference on As After heating sample containing mg As with HS- NH ,SO,-K,SO and dilution with water a portion was further diluted with % HS and % NiSO for measurement of the As by AAS An FI system was set up which provided for on-line acid digestion reduction of AsV to As"' with L- cysteine and HG at a rate of - samples h-' Five As species were separated by an optimized ion chromatographic procedure with the tartaric acid eluate taken to the ICP Arsenobetaine and arsenocholine were removed from urine samples by passage through a Bond-Elut SCX cartridge. Inorganic As and its metabolites were recovered with ethanolic HNO for digestion. A number of 'non-perchloric acid' digestion procedures were compared with the As determined uia an FI procedure.The recommended method employed HNO-H,SO-K,Cr,O-H~ for digestion I n a study of As metabolism mouse tissues with Sr added for internal standardization were digested with HN,-H,O and the As measured byTRXRF in Japanese. The atomic vapour temperature was determined under different conditions. Addition of KMnO was recommended dimethylarsinic acid in ml of urine were sequentially eluted from an AG W-X column. The As in different fractions was measured by [Jrine was diluted + in % HNO,. The diluent included an internal standard In and As spikes for standard additions calibration. Samples were aspirated into an He-ICP. There was signal enhancement due to dissolved Na U and SO,- but this was corrected for by the internal standard A new interface for direct AAS analysis of the eluent from an HPLC column was described which was reported to give equivalent responses for all species and for aqueous or organic mobile phases HN,-HC,-H,S at "C. Samples were also homogenized and arsenobetaine extracted with CHC,-methanol. A portion of the methanol phase was hydrolysed by heating with NaOH and the headspace gas taken for GC with AAS detection Different nebulizers were investigated to link HPLC columns to the detector. A Meinhard pneumatic nebulizer was appropriate where the flow rate was ml min-'. With mini-HPLC flow rates of - pl min-' a direct injection or a high efficiency nebulizer was used 'These workers propose that interferences on As are f C As"' AsV monomethylarsonic acid and FI-HG-AASTotal As was measured after digestion with C As Urine A A;H y ;L As Biological samples MS;ICP;L MS;ICP;L As Urine MS;ICP;L AA;ETA;L As Blood urine As Patent drugs As As As Whole blood Urine Urine A A;H y;L MS;ICP;L AA;Hy;L Tissues XRF;-;S As Urine Urine A A;ETA; L AA;Hy;L As As Urine MS;ICP;L As AA;H y;L AA;H y:L,G As As Muscle Muscle As Biological materials MS;ICP;L R Journal of Analytical Atomic Spectrometry April Vol. Table continued Element As Urine As As As As As As As As As Au Au Au Faeces Matrix Urine Biological tissues Urine Urine Hair nails urine tissue Biological tissues Biological tissues Urine Blood serum urine Biological samples SerumTechnique; atomization; Sample treatment comments Reference MS;ICP;L MS;ICP;L MS;ICP;L MS;ICP;L AA;Hy;L AA;H y;L AE;Hy;L AA;H y ;L Speciation by HPLC on a C,,-bonded silica column modified by treatment with didodecyldimethylammonium bromide in methanol was improved by use of vesicular mobile phases. Eluate from the column was reacted for HG and the release of Hg by CV dissolution acid digestion vapour phase acid digestion dry ashing-were compared. Preparation was complete within - min. Good results were obtained for a range of CRMs by all methods chromatography linked to ICP-MS.The LODs were.-. pg - ' in Japanese Various As species were separated by HPLC on a Dionex AS column and measured with LODs of. -. pmol - ' cetyltrimethylammonium bromide-% propanol-. mol -' borate buffer for chromatographic separation of four As species was developed. No sample preparation was necessary and there was no C- interference Total As and As species were determined in samples from a population where the drinking water contained very high concentrations of As"' Samples collected from subjects with symptoms of toxicity see As ref. were analysed. Solid specimens were prepared in a PTFE digestion bomb CHH-H,O five times.The combined extracts were evaporated the residue dissolved in H,O and As species separated by chromatography. Eluent was mixed with % K,S,O in % NaOH irradiated at nm HG achieved and the ASH pumped to an ICP for AES CHH-CHC CH,OH CHH-H,O was reported. The preferred method was used in As ref. Several methods were investigated to determine As in urine after ingestion of seafoods i. g cysteine was added to ml urine and pl taken min later for FI-HGAAS; ii ml urine +. g K,S,O +. g KOH in a ml conical flask were heated in a microwave oven. Samples were diluted with H,O to ml and the As measured by FI-HGAAS; iii arsenosugars were separated by HPLC on a Phenomenex c, column with ICP-MS for detection A selection of chemical modifiers was investigated and three Rh-Re ascorbate-Pd ascorbate-Rh gave assays which were free from interference.The LOD was. Fg -'. The authors also showed that samples prepared for analysis required stabilization with. g -' NHSCN or. g -' ascorbate evaporated to dryness. The residue was dissolved in mol -' HC dried redissolved and diluted with thiourea. The solution was taken for analysis in a molybdenum atomizer. The stability of samples diluted with.% Triton X- and. mol I-' HCl was investigated. Au concentrations remained constant for d. The three methods gave comparable results but ICP-MS had best sensitivity. LODs were and. ng ml-' for FAAS ETAAS and ICP-MS respectively Techniques for preparation-microwave oven Six As species were separated by ion A micellar mobile phase,. ml -' g of tissue was extracted with % v v Evaluation of three extraction methods Samples were heated with HN and H,Oz and AE;Hy;L MS;ICPL AA;Hy:L AA;ETA;L A A;ETA;L MS;ICPL AA;F;L A AETA;L Journal of Analytical Atomic Spectrometry April Vol. R Table continuedTechnique!; at omizatiom; Element Matrix Sample treatment comments Reference B Biological materials MS;ICP;L A procedure was developed which allowed measurement of B with an LOD of. pg g-'. Dry sample,. g was digested with ml HNO + ml H,O in a microwave oven and the digestate diluted to g with H,O. Accurate analysis of CRMs were obtained with external calibration standard additions or ID calibration. A between-sample wash with NaF reduced memory effects. In the recommended method a Be internal standard was included to compensate for matrix variations boron neutron capture therapy capture therapy were tested. Accumulation of B in cells was measured as part of the study analysed by colorimetric fluorimetric and atomic techniques. Recoveries precision and interferences were investigated and the ICP methods gave best results Absorption of B was investigated measuring isotope ratios after oral administration of IB. Be was used as the internal standard Blood cells were suspended inTriton X- and the slurry sample introduced into the plasma ;Samples from bodybuilders who received B supplements were prepared by microwave digestion. The B had no effect on testosterone or other parameters monitored heating investigated. Pyrolytic graphite tubes and Ar sheath gas were preferred. Atomization was incomplete up to a temperature of °C. Interferences were found at high salt content and standard additions calibration was essential a was measured in deproteinized specimens in a study to determine absorption and excretion of Ba in occupational settings After digestion with acid MgNO was added and p injected into the furnace.The detection limit was pg g-I in Japanese Digestion with HN,-HCI,-HF was carried out in a PTFE bomb. The residue was diluted with. mol I-' HNO and the Be measured with Pd added as chemical modifier Accumulation of Bi in different regions of the nervous system was determined and high concentrations were found in association with fenestrated blood vessels Specimens were digested with HNO in tubes placed in an aluminium heating block. The residue was heated at °C for min with mol - HC and taken for HG. Matrix matched calibration materials were similarly prepared Plasma pharmacokinetics and urinary excretion were measured in subjects receiving Bi-containing drugs and other pharmaceuticals.The distribution of B was determined in dogs after New compounds developed for boron neutron RMs were prepared by microwave digestion and Samples were digested in HNO, with microwave ,lltomization parameters were systematically See Al ref. A suspension of cells in CH,H was sprayed into a heated drying chamber. The suspension dilution was arranged so that an aerosol droplet contained no more than one cell. An air stream transferred the cells to the ICP and each emission pulse was individually determined to give the Ca content of each cell. The LOD was approximately. pg cell - experiment to investigate Ca resorption from bone. Samples were collected for days after an injected dose of Ca to a human volunteer Ascelerator MS was used to measure in an AE;ICP;L AE;ICP;L MS;ICPL AE;ICP;L MS;ICP;L B B Brain bloodTumour cells B Biological materials B Urine faeces MS;ICP;L Whole blood Plasma AE;ICP or DCP;Sl AE;ICP;L B B AE;ICP;L AA;ETA;L B Ba Blood tissues Biological materials AA;ETA;L AE;ICP;L Ba Be Be Plasma urine Liver Urine AA;ETA;L AA;ETA;L AA,-;- Bi Brain neural tissues Plasma tissues AA;Hy;L J Bi AA;-;L Bi Plasma urine Urine Single cells AE;ICP;L AECP;S Ca Ca MS;-;S Ca Serum urine R Journal of Analytical Atomic Spectrometry April VoZ. Table continued ~ ~~ Reference C Technique; atomization; MS;-;S Element Matrix Sample treatmentlcomments Movements of Ca following cardiac ischaemia and reperfusion were investigated in animals using a Ca probe measured by accelerator MSTotal body Ca was measured in uiuo in rats by dual- energy X-ray absorptiometry. Rats were then killed the skeleton isolated and ashed for determination of the Ca by AAS. Results were highly correlated measurement of Ca and K. The sample was automatically diluted and separated to go to separate detectors Changes in metal concentrations were measured in drug induced cardiac arrhythmias in Chinese Isotope ratios were measured in a study of the bioavailability of minerals from different food types Hair samples were washed with % CH,COOH dried and digested. Specimens of plasma were diluted in H,O for ICP-AES. Beard shavings were analysed by XRF without any treatment Cochlea fluid p was diluted with pl.% La solution for pulse sampling FAAS in Chinese Ca Cu Mg and Zn were measured in patients with healing of bone fractures in Korean.The reference range established from healthy blood donors was found to be.-. mmol l-l which is lower than in previous studies An FI manifold provided for simultaneous See Ag ref. Ca Ca Ca Ca Ca Ca Ca Ca Ca Cd Cd Cd Cd Cd Cd Tissues Bone AA;F;L Serum AA;F;L AA;F;L MS;ICP;L AE;ICP;L XRF;-;S Serum Urine faeces Hair beard plasma Perilymphatic fluid Whole blood Serum AA;F air-CH;L AE;ICP;L AA;F;L AE;F;L AA;F;L AA;F;L A AETA;L Lobster digestive gland Urine A precipitate with an APDC-Fe complex was formed in a cm knotted PTFE tube. The precipitate was dissolved in IBMK and introduced into the AA spectrometer in this FI procedure in Chinese See As ref. CThree methods ashing at "C digestion with HN,-HCl-HCIO and autoclave digestion were compared. The third procedure was preferred by the authors.-. g liver was digested with ml HN and diluted with H to ml. Specimens from deer had concentrations of <.-. mg kg-I Cd compounds were separated by HPLC which was connected by a novel thermospray interface to the AA spectrometer. The interface removed the sample solvent and presented the fine particles directly to the base of the flame. With this arrangement the sensitivity was increased -fold over conventional nebulization ,-bis di-pyridyl-methylene thiocarboh ydrazine was used to extract Cd Five elements in maternal and cord blood were measured by AAS and ion chromatography to determine whether there is placental transfer An on-line FI system was proposed where the Cd coprecipitated with dithizone through a knotted reactor.The precipitate was dissolved in IBMK and transferred to the graphite furnace. This method had an LOD of. pg -l. See Cd ref. in Chinese Samples were acidified and the Cd trapped on an anion exchange resin. The eluted Cd was thus separated from alkali metals. The authors developed a kit to simplify the procedure Cd in tissues of non-occupationally exposed subjects Ammonium diethyldithiophosphate promoted adsorption for concentration of analyte and separation from salt matrices. g powdered medicine was heated in a platinum crucible at and "C for and min respectively. After cooling the residue was dissolved in ml % HNO and diluted to ml with H in Chinese In uiuo XRF was sufficiently sensitive to determine Blood urine Herbal drugs MS;ICP;L AA;F;L AA,ETA;L Liver Urine sweat AA,F;L Cd Cd Biological samples Whole blood AA;ETA;L AA-;- Cd Blood AAETA;L Cd Blood AA;ETAL Cd Cd Cd Kidney Biological materials Chinese medicines XRF;-;- AA;ETA;L AA;ETA;L Journal of Analytical Atomic Spectrometry April Vol. R Table continuedTechnique atomization; AA;ETA;L Sample treatment comments chemical modifier. Samples were also analysed by ASV ,-Bis [ - -pyridy ethylidenel thiocarbanohydrazide was used for extraction of Cd. With an aqueous:organic ratio of the LOD was. ng ml-' Specimens from dental technicians diluted with H,O were analysed for Cd Cr and Ni. Blood Ni concentrations were higher than in control subjects in Korean NH,H,PO was used as modifier. A + dilution and ppm of PdNO were used for Cd.There were no interferences and the LOD was. ng ml-' in Japanese ICI reagent g KI- g ascorbate in ml H,O was added to ml of acidified urine. Analytes were extracted into YO tri-n-octylamine in but-yl acetate and Zeeman effect background correction was used in work to assign certified values to RMs Residues after digestion with HN,-HCl were taken into % thiourea-% ascorbate- YO phenanthroline-. mol -' HCl and sampled into an FI manifold for further mixing with DDDC in a knotted coil reactor. The complex was adsorbed onto the reactor walls and then eluted with IBMK into the flame Lyophilized tissue specimens were digested with HN,-HC the residues dissolved in NaOH and the pH adjusted to. Cd was extracted into IBMK-l$bis [ phenyl- - pyridyl methylenel thiocarbonohydrazide and the organic phase separated for measurement of Cd hdetal profiles of different metallothioneins were examined by HPLC separation.The study included the determination of redox state by measurement of Cd binding in the presence and absence of a reducing agent. A laboratory manufactured unit linked the column eluant to a quartz 'microatomizer furnace' for AAS Fluids were diluted with H and Pd used as ]Blood samples were diluted + and % Powdered sample was placed on a L'vov platform See Cd ref. Reference Element Matrix Cd Dialysis fluids Cd Biological samples AE;ICP;L Cd Whole blood A A;ETA;L Cd Whole blood urine AA;ETA;L AA;F air-C,H,;L Cd Urine AA;ETA;S AA;F,air-C,H ;L Cd Tissue Cd Hair Cd Biological materials AE;ICP;L MS;ICP;L AA;F OZ-H ;L Cd Metallothionein Cd Metallothionein Cd Hair MS;ICP;L AA;ETA;L AA;F O,-H,;L Washed hair samples from children living in different areas were collected and digested to monitor exposure to Cd and Pb blood or.% HNO urine were assayed. Modifiers were investigated and PdNO ,-MgNO gave best results with different RMs and when matrix matched calibration was used.The modifier was purified by injection onto the L'vov platform and heating at "C; the sample was then placed on top. The LOD was. pg -' Changes in concentrations of Cd Fe and Zn were determined in skin after exposure to low-dose X-rays With an on-line column of D chelating resin - mesh an enrichment factor of. was obtained. Experimental conditions were optimized and the LOD was. ng ml-' in Chinese Scrum and H,O :l with PdNO solution added was injected into the furnace. Aqueous calibration provided for an assay with an LOD of. pg -' Samples diluted + with.%Triton X- See Cd ref. Tissue disposition of Co was determined after :ml sample was digested by acid and Co in the administration of CoC or Co-protoporphyrin residue was extracted as the APDC chelate into IBMK. Precision was good no interferences were found and the LOD was < nmol -' Cd Whole blood urine AA;ETA;L AA;-;- Cd Skin Cd Liver AE;ICP;L c o Serum AA;ETA;L AA;F;L A A;ETA;L c o Liver co Tissues c o Serum urine AA;ETA;L R Journal of Analytical Atomic Spectrometry April k d. Sample treatment comments Reference C Element Matrix c o Whole blood A A;ETA;L In a continuous system blood was pumped from a catheter in a patient's vein and mixed with anticoagulant and HNO for on-line microwave digestion. An aliquot pl was automatically removed from the effluent stream and injected into a graphite furnace with p MgN , for measurement of Co. With no opportunity for contamination the LOD was. pg -' Fetotoxicity of Co was demonstrated in mice rats and rabbits in Hungarian Samples were injected into the furnace after dilution + with H,O. Pd NO chemical modifier was added and standard additions were used for calibration.The LOD was. pg -' was digested with HNO, + in a pressure bomb. Measurement techniques including cathodic stripping voltammetry were compared. The lowest LOD,. pg I-' was obtained with ICP-MS In uitro binding to serum proteins was investigated. Bound and free fractions were separated by dialysis ingested g K,Cr in a suicide attempt in Portuguese Ashing at "C eliminated interferences and no background correction or chemical modifiers were neccesary.The heating programme was reduced to s correction were compared. Injection of sample into a pre-heated furnace was also examined. A method with slow hot-injection and Zeeman background correction gave good results with a CRM and had an LOD of. pg -' Serum samples were diluted with % HNO, blood Blood samples were analysed from an individual who Tungsten lamp and Zeeman effect background See Cd ref. Biological fluids were diluted + with.% Triton X- blood or.% Triton X- in mmol I-' HNO urine. Bone was digested in HNO,. Solutions were taken for ETAAS with standard additions calibration. LODs were and ng -' with deuterium or Zeeman background correction respectively and multiple aliquots were injected into the furnace to reduce the LOD of the assay.The sample was dried and ashed after each injection and was used to prevent C accumulation in the tube in Japanese See Cd ref. A transversely heated graphite tube was used with Specimens were diluted -fold with Pd-Triton X- MgN as the chemical modifier. The LOD at. pg I-' was lower than seen with a conventional furnace Increased concentrations of Cr were found in blood plasma and urine from subjects with occupational exposure below the Maximum Exposure Limit for Cr"'. mg rn-,. A modest increase was also found in lymphocytes. No increase in DNA strand breakages in lymphocytes were found. Lymphocyte and urine -hydroxy-deoxyguanosine concentrations were also normal ICP-MS for the determination of Cr was reviewed. Digestion procedures calibration ICP operating parameters were investigated to minimize polyatomic interferences. Best results were achieved with a % air-Ar plasma which gave an LOD of pg ml-' See Co ref. Zeeman effect background correction on two different instruments from the same manufacturer were compared and found to be quite different AA;ETA;L AA;ETA;L c o c o Blood Serum c o Whole blood serum AA;ETA;L MS;ICP;L c o Cr Cr Serum Plasma erythrocytes Biological samples AA;ETA;L AA;-;L AAETA;L Cr Urine AA;ETA;L Cr Cr Chinese medicines Blood bone urine A A; ETA; L AA;ETA;L Cr Serum whole blood AA;ETA;L Cr Cr Whole blood Urine AA;ETA;L AA;ETA;L Cr Whole blood plasma A A;ETA;L lymphocytes urine CrTissues MS;ICP;L Cr Cr Serum Serum urine AA;ETA; L AA;ETA;L Journal of Analytical Atomic Spectrometry April Vol. R Table continued Element Cr Plasma Matrix c u Serum urineTechnique; atomization; Sample treatment comments AA;ETA;L A preliminary enzymic digestion was adopted before injection into the graphite furnace. Samples collected following an oral intake of Cr"' had higher concentrations when ascorbate was included in the dose Serum and urine were diluted + and + respectively with.% Triton X- in ml-' HNO,. The LODs were. for serum and. pmol - for urine. Dry and ash phases were simplified to reduce the analysis time to s AA;ETA;L See Ag ref. c u Lobster digestive gland AA;FL c u Vitreous and aqueous A A; ETA; L AA;ETA;L humour c u Serum AA;ETA;L c u Biological materials A A;ETA;S c u Herbal drugs c u Biological samples c u Liver c u Tissues c u Liver cu Plasma c u Plasma blood cells c u Biological materials c u Serum c u Mammoth bone c u Liver AA;F;L.__- AE;ICP;L AA;-;- A A;ETA;L AA:F;L AA;F;L AA;F;L AA;ETA;L A A;ETA;L AA.-- AA;F;L A A;ETA; L c u Heart perfusion fluid AA;-;L c uTissues c u Urine faeces cu Stomach intestines AA;ETA;L MS;ICP;L MS;ICP;L pl sample was mixed with ml of mmol I-' HNO and pl injected into the furnace in Chinese injected into the furnace. No interferences were observed in Chinese A vertical column atomizer made from glassy carbon packed with activated charcoal was constructed. This was fixed within a stainless steel housing or 'atomization chamber' which was electrically heated. With these materials a maximum temperature of "C was achieved for isothermal atomization of the sample from a graphite cup suspended immediately above the glassy carbon column. Vapours were transferred by a flow of Ar through the column and non-atomic vapours were adsorbed onto the charcoal. Atomic vapour passed into the light path and background correction was not required pl of the sample diluted + with. mol I-' was See Cd ref. ,dvantages speed precision and disadvantages incomplete breakdown of microwave digestion were discussed in German Metal distribution profiles were studied in different stages of hepatocellular damage in the LEC rat a model for genetic disorders of Cu metabolism Administration of tetrathiomolybdate to LEC rats reduced the content and altered the subcellular distribution of Cu in liver. Some alteration to Zn in tissues was also observed. Severe jaundice was also cured An impressive discussion was given of approaches to reduce analysis times by simplification of digestion procedures and reduction of the drying and ashing steps in ETAAS. Other developments were also presented metabolism were found to be abnormal in samples from asthmatic children Concentrations were similar in diabetic children and their controls See Cd ref. Elinding of Cu to serum proteins was investigated. Proteins were separated by gel chromatography Concentrations across a cross-section of bone were measured l h e mechanism for development of hepatitis and the role of Cu-metallothionein was investigated by measurements of Cu and the protein in subcellular fractions from normal and diseased liver in Japanese were shown to contain sufficient Cu and Fe to promote autoxidation and tissue damage.The contamination was traced to solid NaC NaHCO, KC CaCTrace elements and other markers of oxidative Some buffer fluids used in isolated heart experiments See Al ref. See Ca refThis work is described in more detail in Various soft tissues ref. Reference R Journal of Analytical Atomic Spectrometry April Vol. Sample treatment comments Reference and R Element Matrix c u Plasma blood cells A A; ETA; L Samples were collected from patients with diabetes. White cells were isolated from ml of blood by density gradient centrifugation. The cells were digested in mol -' HNO and portions were taken for ETAAS which included an ashing step. The sample was diluted + with.% Triton X-. pl was taken for first-order-derivative FAAS in Chinese catecholamines were measured in different regions of the rat brain after manipulation of the diet Changes in the concentrations of Cu and See Ca ref. Concentrations of Cu and Zn were measured in term infants at birth and after months feeding with breast or formula milk determined by weekly measurements for months collected from the day of delivery to days post partum.The mean Cu concentration in tears was. ppm. There was no correlation between Cu in tear and serum samples g of powdered material in a ml Nessler tube was heated at "C for h with ml of % v v HNO,. The suspension was filtered diluted to ml and taken for analysis Intra-individual variation in concentration was Concentrations remained constant in samples See Cu ref. c u Whole blood AA;F;L c u Brain AA; ETA;L c u c u Whole blood Plasma urine A E;I C P; L AA;ETA;L c u c u Plasma AA;-;- Breast milk AA;ETA;L c uTears serum AA;-;L Chinese medicines c u AA;F;L Vitreous and aqueous Liver Liver humour AA;ETA;L Fe Fe Fe AE;ICP;L A A;ETA;L AA;F;L AE;ICP;L MS;ICP;L AA;-;L AA*-*- AAIETA;L AA;ETA;L See Cu ref. See Cu ref. Biological materials Heart perfusion fluid Urine faeces Skin Breast milk Plasma See Al ref. See Cu ref. See Ca ref. See Cd ref. See Cu ref. Plasma,. ml was mixed with. ml diluent containing.% Ca-.% Triton X- Yo HNO,. A two-stage ash sequence was employed with heating to and then °C. Good recovery and precision were observed and an LOD of. ng was obtained in Chinese modifiers was reported in Chinese and Sr blood samples were analysed without treatment Inorganic and organic modifiers were investigated programme temperatures were optimized and mechanisms of signal enhancement were discussed in Chinese didodecyldimethylammonium bromide gave good HPLC separation of Hg" and methylmercury in a linked technique with detection by a CVAAS system.The assay also featured good sensitivity with an LOD of.-. pg -' volatile ethyl derivatives of Hg" and methylmercury formed and collected on a GC column. Compounds eluted from the column were reduced to elemental Hg and measured by CVAFS heated at °C for h. The solution was cooled to - "C for h followed by the addition of. mol -' bromine chloride in mmol -' HC. After h H,O and SnCl was added and Hg vapour removed to Au-coated sand by a stream of He. Thermal desorption caused release of the trapped Hg which was detected by AFS and the LOD was pmol - An investigation of graphite tubes and chemical With a chemical modifier which included NH ,NO A vesicular mobile phase of Samples were treated with ethanolic KOH the HN,-H,SO was added to the sample and Fe Fe Fe Fe Fe Ge Ge Serum Ge Whole blood AA;ETA; L AA;ETA;L Ge Serum A A;ETA;L Hg Urine AA;CV;L Hg Biological specimens AF;CV;L Hg Urine breast milk kidney AF;CV;L faeces Journal of Analytical Atomic Spectrometry April Vol. Table continued Element Hg Hair urine Matrix Hg Whole blood Hg Blood urine Hg Liver Hg Biological tissues Hg Hair Hg Brain Hg Hair Hg Mouthwash Hg Urine Hg Urine Hg Urine Hg SerumTechnique; atomization; Sample treatment comments AAi-i- AA;CV:L A A;CV;L AA;CV;L MS;ICP;L AA;CV;L AE;CV:L AA;CV;L AA;CV;L AF;CV;L AA;CV;L AA;CV;L A A;CV;L n FI procedure was used to mix. ml liquid sample with H and to react the Hg with HC and KBH,. Separated Hg vapour was carried to an Au-coated graphite tube for collection.The tube was heated to °C for desorption of the Hg. The LOD was pg in Chinese See Cd ref. !Samples were digested with acid in sealed bombs and heated either in a conventional oven or by microwaves. Similar results were obtained with either procedure but the microwave method was much faster I-Iomogenized tissue was acidified to release protein- bound species centrifuged and cysteinato complexes formed. The inorganic methyl- and ethylmercury species were separated by chromatography with a laboratory-made interface to link to the AA spectrometer Tissue was digested with NaOH NaCl and cysteine with two approaches to this step either a block heater at "C for h or digestion at -°C overnight. Comparable results were obtained. Selective reduction with SnC or SnC,-Cd was employed to determine Hg" or total Hg respectively Segments of hair were dissolved in HNO at room temperature overnight for determination of the distribution profile along a single strand Evidence was presented for the overestimation of inorganic Hg by the Magos procedure. A proportion of methylmercury could be rapidly degraded and measured as Hg". A correction procedure was proposed An FI technique was described which mixed acidic Sn reagent with sample. A stream of He transferred Hg vapour from a gas-liquid separator to a quartz tube containing a gold-film lining where it also provided a DCP. Resistive heating of the film desorbed the Hg into the He plasma for AE mixture of nonpolar.-% NaCl and polar solvent paraffin or an edible oil ml of urine was mixed with ml HNO and ml HS for min. ml of. mol -' KMnO was added the solution decolorized with. mol -' oxalate and diluted to ml with H for HG by addition of ml SnCl in French. mol -' KBr-. mol -' KBrO reagent was used to release Hg" from organic species rapidly. Excess Br was removed with % hydroxyammonium chloride and the diluted solution taken to an FI system for reduction CV generation and AFS.The LOD was ng -' Hg vapour from dental amalgam was collected into a See As ref Hg and Se were measured in specimens from residents of different regions of the Czech Republic in a study of cardiovascular disease analysed together with cerebrospinal fluid Hg by NAA Organomercury compounds were satisfactorily separated by capillary GC with MIP-AES detection subjects. Specimens were digested in sealed PTFE containers. Hg vapour was trapped by Au amalgam formation before measurement by AAS For inorganic Hg,. g sample +. ml mol - ' HS were mixed and heated overnight at "C. ml H,O+antifoam were added and the sample taken for CVAAS.To measure total Hg the sample was digested with HN,-HClO at "C. ml % urea solution and ml H were added the sample was sonicated for min and the sample taken for CVAAS.The apparatus included a gold trap for preconcentration of the vapour Samples from workers exposed to Hg vapour were Normal concentrations were assessed in Japanese Hg Plasma erythrocytes urine AA;CV;L Hg Biological samples AE; MP;L Whole blood urine AA;CV;L Hg Hg Whole blood erythrocytes AA;CV;L Reference lC R Journal of Analytical Atomic Spectrometry April Vbl. AA;Hy;L MS;ICP;L Sample treatment comments See Cu ref. A combustion procedure was developed for solid samples with dissolution of residues in. mol -' NaOH.The LOD was. pg I - ' Washed hair was ashed at °C for h the residue dissolved in ml HC :l and diluted to ml with H. Atomization from a graphite probe was employed in work which determined the normal range to be - ng g-'. The LOD was. pg in Chinese intratracheal instillation of InP were prepared by acid digestion or by extraction with methyltricaprylammonium ions. Absorption tissue distribution and excretion were determined An ArF laser focused onto a very fine flowing sample stream produced a luminous vapour. Emitted light was transmitted to a monochromator and detector. Configuration of the flow cell gave a flow rate of -SO p mol min-' and with careful operation the concentration in single cells could be determined Cells were separated from ml blood and ashed for the measurement of K and Mg in Japanese See Ca ref. See Ca ref. - mg tissue was homogenized in ml ofTissues from animals with oral exposure or mmol -' HCl and the supernatant was diluted + with H Matrix interferences associated with C were eliminated by use of an in situ Ta-coated atomizer. Picomolar concentrations were determined Endogenous Li clearance was calculated from data determined by ETAAS. Results were similar to those determined after administration of Li and measurement by FAAS. The performances of ISEs and a colorimetric method were compared with AAS and AES. Various interferences were reported in the non- atomic procedures.The assay had an LOD of pg I-' and was used to show that there was no dermal absorption of Li during immersion in a hot spa sanitized with lithium hypochlorite See K ref. See Cu ref. See Al ref. Concentrations were determined before and after treatment with Mg in women with pre-eclampsia and in controls. Erythrocyte Mg levels were low in the pre-treatment samples increased post- treatment but were still below the normal values See K ref. Lymphocyte Mg was low in patients with essential hypertension and increased in subjects with renal hypertension compared with controls patients with essential hypertension treated with thiazide diuretics. Subjects also given K-sparing drugs did not show this reduction Mg was precipitated from samples by -hydroxyquinoline and "Mg added for calibration of theTIMS measurement by internal standardization. Interferences from urine matrix were removed by a preliminary cation-exchange step Concentrations of Mg in plasma and monocytes were low in diabetic children compared with their controls Plasma and blood were diluted + and + respectively with.% HNO for calculation of the Mg concentration in erythrocytes from patients with chronic fatigue syndrome. Levels were not different to those of controls Intracellular Mg concentrations were reduced in See Ca ref. Reference Element Matrix Hg Chinese medicines I Serum milk tissues AA;ETA;L In Hair In Tissues AA;ETA;L K Erythrocytes AE;laser;L K Monocytes AA;-;L S K K K Serum Serum Heart and skeletal muscle AE;F;L AA;F;L AA;F air-CH,;L K Renal tubular fluid AA;ETA;L Li Serum urine AA;ETA;L AE;F;L Li Serum AA;F;L AE;F;L. Li Serum AA;ETA;L Li Renal tubular fluid Mg Biological materials Mg Urine Mg Plasma erythrocytes AA;ETA;L AA;ETA;S AE;ICP;L AA;-;L Mg Monocytes Mg Lymphocytes Mg Erythrocytes AA;-;L Mg Serum urine MS;-;S Mg Plasma blood cells Mg Plasma whole blood AA;F;L AA;F air-CH,;L Mg Serum AA;F;L Journal of Analytical Atomic Spectrometry April Vol. R Element Mg Mg Mg Mg Mn Mn Mn Mn Mo Matrix Choroid-retina Sample treatment comments Mg and Zn were measured in specimens from chemically-induced diabetic rats in an investigation of the mechanism of optical dysfunction in Japanese - mg was homogenized with ml of mmol I-' HCl and the supernatant was diluted + with H. Mg was measured at. nm fractions in serum. Changes in the concentrations of each were associated with clinical disorders 'Various approaches were used to identify Mg !see Ca ref. See Cu ref. See Cu ref See Cu ref. See Fe ref. Samples were injected without preliminary treatment and the modifier MgNO in.%Triton X- was added in the furnace.The LOD was. pg I-' in Spanish Samples were analysed after dilution with H. An injection of.% HNO was used between samples to remove memory effects and the LOD was. pg I-' were dissolved in mol - HCI. Fe" and ascorbate were added to prepare the sample for an FI system which was developed to coprecipitate Mo with Fe"-pyrrolidin-yldithioformate pyrrolidinedithiocarbamate in. mol - ' HCI on the walls of a knotted reactor. The precipitate was dissolved in IBMK which was directly loaded into the graphite furnace.The LOD was. A solution of mg I-' PdN ,- mg -' After digestion of hair with HN-HC, residues MgNO was added to serum and an aliquot injected into a graphite furnace for atomization into the ICP. Measurements were made at mjz and and the LOD was. pg - See K ref. See Ca ref Na was measured at. nm. See K ref. See Cd ref. This review considered sample collection and storage details of preparation and the measurement of Ni Solvent extraction was used to separate Ni isotopes from interferences due to Ca and Na. Mass numbers and were used for counting while was used for isotope dilution in a study of Ni metabolism in volunteers IBMK- ,-bis [ phenyl -pyridy methylenel thiocarbonohydrazide. A maximum aqueoworganic phase ratio of was possible with these materials Tissues were microwave digested. Ni in the residues and in urine was extracted with ,-bis [ phenyl -pyridy methylenel thiocarbono- hydrazide in IBMK Interferences from Ca were reduced by multivariate calibration with principal components analysis.The higher concentrations of Ca in urine were reduced by coprecipitation with oxalate. Experimental data after administration of Ni and 'jNi were presented Ni was extracted into See Cr ref. Set Cd ref. ml serum ml H,O and ml of mol I-' HNO were mixed and centrifuged. The supernatant was mixed with. ml of.% ammonium vanadate,. ml of pg ml-' La and diluted to ml with ,O. An aliquot was injected into an Mo-coated graphite tube and the LOD was ng ml-' A iransversely heated graphite tube was used and the ],OD at. pg I-' was lower than seen with a conventional furnace Reference AE;ICP;L Heart and skeletal muscle AA;F air-CH;L AA;F;L Plasma Whole blood Biological materials Plasma Mammoth bone Breast milk Serum AE;ICP;L A A;ETA;S AA;F;L AA;F;L AA;ETA;L A A;ETA; L Mo Whole blood Mo Hair AA;ETA;L AA;ETA;L Mo Serum MS;ICP;L Na Na Na Ni Ni Erythrocytes Serum Renal tubular fluid Urine Serum urine AE;laser;L AA;F;L AA;ETA;L AA;F;L AA;ETA;L Plasma urine faeces MS;ICP;L c NiTissues serum urine AA;ETA;L Ni AE;ICP;L Ni Tissues urine Ni Serum urine MS;ICP;L Serum whole blood Whole blood Serum AA;ETA;L A A; ETA; L A A;ETA; L Ni Ni Ni Ni Urine AA;ETA;L R Journal of Analytical Atomic Spectrometry April Vol. Sample treatment comments Reference Element Ni Serum Ni Urine Matrix See Co ref. APDC complexation and enrichment with activated carbon were used to concentrate Ni from ml urine.The method had an LOD of. pg I - ' Organolead compounds were separated by GC with AAS for detection and quantification Samples were prepared by precipitation of protein with HNO,. The analytical time was reduced by a device to start the autosampler before the furnace programme was completed. ng ml-' in. mol -' HNO were mixed for s centrifuged and pl of supernatant taken for analysis with ETA into the ICP. The plasma Pb was. ng ml-' Specimens were diluted + with.% Triton X- with pg -' Pd % citric acid and. mol -' HNO,. The LOD was reported to be pg -' in Spanish Standard additions calibration was used to determine Pb in undiluted blood. The mean concentration in samples from children was. pmol I-' in Chinese Calibration standards prepared in % HNO and blood specimens from children were diluted + with.%Triton X-.% NH,HP-.% HNO,. Accuracy was demonstrated by analysis of RMs and the LOD was pg -' C ml sample-. ml HNO,-O.I ml Pb See As ref. C C See Al ref. C C See Cd ref. A specimen bank with tissues collected from individuals who were workers at a Cu-Pb smelter and a control material has been set up. Procedures for sample collection and storage were described. To investigate questions such as temporal variations risk assessment etc. elements were measured by NAA and Pb and Zn were determined by AAS See Cd ref. Blood pl was placed onto a tungsten filament electrode. Microwave irradiation was used to dry the sample and then ignite the He plasma. An LOD of pg was found. See also Pb ref. An on-line FI manifold was described that diluted the sample and added an internal standard.The nebulizer setting was found to be critical to the achievement of good precision RSD < YO Samples were spiked with Pb and a complex formed with lithium bis trifluoroethy dithiocarbamate. This was further derivatized with -fluorophenyl magnesium bromide for GC-MS which was uncomplicated by memory effects. Analysis of RMs was satisfactory A technique for the in uiuo measurement of Pb using injected Tcm as an internal excitation source was investigated in an experimental model. The described system required a radiation dose which was too high for use and modifications to improve sensitivity were suggested Pt was constructed using Tc" determined by in uivo XRF An in v i m approach to the measurement of Pb and. The authors propose that long-term exposure can be See Cd ref. An overcorrection error is found when transversely heated graphite tubes with longitudinal Zeeman background correction is used to measure Pb in bone at nm.This was not observed when longitudinal heating and transverse Zeeman background correction were used or if D background correction was employed See Pb ref. A A;ETA;L AA;F;L Pb Biological samples AAi-i- Pb Whole blood A A; E TA;L Pb Plasma MS;ICP;L Erythrocytes A A; E TA; L Pb Pb Pb Blood Blood A A;ETA;L AA;ETA;L c Pb Pb Pb Pb Blood urine Blood Herbal drugs Tissues MS;ICP;L AA;ETA;L AA;F;L AA-;-; Pb Pb Whole blood Whole blood Pb Urine MS;ICP;L Pb Blood urine MS;GCL Pb Bone XRFi-i- Pb Kidney XRF;-;- Pb Bone XRF;-;- Pb Pb Biological materials Bone AA;ETA;L A A,ETA;L Pb Whole blood AE;MIP;L Journal of Analytical Atomic Spectrometry April Vol. R Table continued Element Matrix Pb Whole blood Pb Pb Pb Pb Pb Pb Chinese medicines Bone Whole blood Sweat urine Dialysis fluids Whole blood PbTeeth Pb Whole blood tissues Pb Tissue Pb Whole blood Pb Bone Pb Whole blood Pb Whole blood Pb Whole blood Pb Tissue sections Pb Hair Pb Blood Pb Neural tissue kidney Pb Chinese medicines Pb Whole blood Technique; atomization; Sample treatment comments AA;ETA;L MS;ICP;L MS;ICP;L MS;ICP;L MS;-;-L AA;ETA;L AA;ETA;L MS;ICP;L AA;Hy;L AA; ETA$ AA;ETA;L AA;ETA;L AA;ETA;L AA;ETA;L AA;ETA;L AA;ETA;L AA;F;S AA;ETA;L AA;-;- AA;F;L AA;ETA;L AA;ETA;L Blood samples were diluted + with % v v Triton X- centrifuged and the supernatant taken for measurement of Pb in an epidemiological survey which suggested that more than % of children in Saudi Arabia have blood Pb concentrations greater than pg dl-' See Cd ref. Pb isotope ratios were measured in bone and other archaeological samples to determine likely sources of exposure in ancient populationsTwo aliquots of blood. ml were weighed and one spiked with an NIST Radiogenic Pb Isotope Standard to give an ID assay. The two aliquots were digested with HNO and the residues diluted with H for aspiration into the ICP. The concentration of Pb was calculated from the 'O'Pb and Pb signals Dermal absorption of Pb" was investigated using Pb-enriched test samples. Sweat and urine specimens were analysed by TIMS and ICP-MS :See Cd ref. Blood diluted + with g -' NH,HP- ml -' HNO,-. ml I-' Triton X- was mixed and pl injected onto a L'vov platform. A short heating programme was used to increase throughput and results agreed well with other methods 'The 'Pb:Pb zo*Pb:Pb and osPb:Pb ratios were measured in an attempt to identify which environmental sources of exposure contribute to the body load Residues after digestion with HClO,-HNO were diluted with. mol -' HC. ml from the solution was injected into an FI manifold to mix with % nitroso-R salt in mmol -' NaOH and with.% NaBH for HG.The LOD was pg -' but there was some interference from Se" See Cd ref. ml. mol -' HNO in.% Triton X- was added to. ml blood left for min and centrifuged. The deproteinized supernatant was analysed by AAS See Pb ref. A simple low-cost prototype instrument was developed for measurement of Pb in blood. It includes a tungsten filament atomizer and Smith- Hieftje background correction. Problems with accumulation of C remain to be overcome An instrument and analytical procedure were set up for rapid measurement of Pb in large numbers of blood samples developed for the measurement of Pb in blood. It includes a tungsten coil atomizer powered from a car battery and measures non-atomic absorption at the unabsorbed Pb line at. nm for background correction the association with other elements were demonstrated See Cd ref. An improved filter-paper micro-cup FAAS method was compared with an established ETAAS procedure. Good agreement was obtained when strict precautions to prevent contamination during sample collection were in place Axonal transport of Pb could not be demonstrated in a study of the mechanism of development of motor neurone disease See Cu ref. Blood specimens diluted ten-fold with. % v v A dedicated low-cost portable instrument was Incorporation of Pb in sub-cellular structures andTriton X- were analysed using pg I-' -% m v citric acid-. mol -' HNO as the chemical modifier. Increased concentrations were found in patients with essential hypertension Reference C C C C R Journal of Analytical Atomic Spectrometry April Vol. Table continued Element MatrixTechnique; atomization; Sample treatmen tlcommen ts Pt Pt Pt Pt Pt Pt Pt Pt Ru Sb Sb Sb Sb Se Se Se Se Serum urine Lymphoma cells AA;ETA;L MS;ICP;L Tissues M S;ICP;L MS;ICPS Kidney XRFi-i- Plasma ultrafiltrate AA;ETA;L Kidney cortex and medulla AA;ETA;L Plasma ultrafiltrate whole A A;ETA; L blood Plasma urine AA;ETA;L Liver kidney AA;ETA;L Urine AA;ETA;L Whole blood serum Serum tissues Blood urine Serum Serum Blood serum Urine A F;ETA; L AA;Hy;L AA;ETA;L AA:ETAL AA;ETA;L A A; H y; L AA;ETA;L Pt Pharmaceutical preparations MS;ICP;L Pt species were separated by HPLC coupled to the ICP-MS via a laboratory-made interface. Eluent from the column passed through a pneumatic nebulizer to a heated spray chamber and was desolvated by a membrane drier tube and cryogenic condenser Methods for measurement of Pt in body fluids were given.The LODs were - ng ml- ' in German Cells cultured in the presence of cisplatin were sonicated for min and digested with. ml of HNO at °C for h. Solutions were diluted and the suspensions introduced into the plasma via a nebulizer pharmacokinetics of Pt-chemotherapy A review of ICP-MS applied to studies of the See Pb ref. Pharmacokinetics of carboplatin were determined in children with malignant tumours. Data were similar to those reported in adults Pt concentration post mortem was examined relative to a range of factors time since last injection size of dose hydration regime etc. with a view to improving treatment with cisplatin Antifoam-B for measurements in pharmacokinetic studies of enloplatin with ormaplatin a new platinum anti-cancer drug microwave oven. HNO was added ml per g of tissue and heated. After cooling HNO and HzOz were added and. ml per g of tissue respectively with further heating.The digestate was evaporated to ml and diluted to ml with H for measurement of Ru. Standard additions calibration was employed with Ru added to portions of the homogenate and the LOD was ng g-' A ml sample was adjusted to pH <. ml of % cupferron was added and the Sb chelate extracted into ml of IBMK. pl was injected into the graphite furnace. Concentrations of Sb in control subjects refinery workers and battery manufacturers were reported LEAFS with atomization within a graphite furnace was described. Measured concentrations were around pg ml-' considerably below previously reported values Concentrations of Sb"' and SbV were measured in Leishmania infected hamsters treated with an Sb-containing drug Samples were diluted withTriton X- in a study of the pharmacokinetics of sodium stibogluconate in patients with leishmaniasis Samples were mixed with a modifier,.% ascorbate +.% Triton X- and pl was injected onto p.% Pd solution in Italian Different Se-containing species were separated by concanavalin A affinity chromatography and the Se measured with an Ag-Cu-Mg modifier Blood,. ml was heated with ml HN,-HClO :l at °C and then with ml of mol I-' HC.This solution was diluted to ml with H and. ml taken for an FI procedure for HG which gave an LOD of. pg I-' in Chinese tetrakis -fluorophenyl borate was collected either by solvent extraction or on a. pm pore size cellulose nitrate filter. The Se was then measured with a Pd chemical modifier. Similar detection limits ng ml-' were achieved using both procedures but the filter collection method was more precise Samples were diluted with Triton X- and Pharmacokinetic and other studies were conducted Homogenized tissues were heated gently in a An ion pair of trimethylselonium ion with Reference C Journal of Analytical Atomic Spectrometry April Vol. R Table continued Element Se Hair Se Urine Matrix Se Biological tissues Se Se Se Se Se Se Se Se Se Se Se Se Se Medicines Dietary supplements Serum urine Biological samples Hair nail Plasma Urine Biological materials Blood urine Serum whole blood Urine Muscle Biological samples Se UrineTechnique; atomization; Sample treatment comments A A;ETA;L AA;F;L A A;ETA; L AA;ETA;L A A; ETA; L AA;ETA;L AA:Hy:L Cattle with acute heart failure had much lower hair Se concentrations than were found in healthy animals from another region in Spanish Organoselenium species were digested with hydrobromic acidlbromide reagent for HG. An FI manifold was set up to form transfer and trap the H,Se in a graphite furnace.-. pg of powdered sample was placed into a graphite cup-in-tube and two modifiers Pd in.%Triton X-. g I-' pl and. g - Cu pl added. Calibration was carried out with standard solutions in % HNO H,O-NiNO for measurement of Se in a coated graphite tube in Chinese Conditions for the separation of selenite and selenate by ion chromatography were investigated. Potassium hydrogenphthalate at mmol I-' saturated with NiOH , was the preferred mobile phase. The LODs with ETAAS detection were ng selenite and. ng selenate. The equivalent figures for FAAS detection were and ng respectively A wide range of chemical modifiers was investigated to determine their effect on the thermostability of selenite selenate selenomethionine and trimethylselonium. None had the same effect on all Se species but. pg Pd- pg MgNO gave accurate results with CRMs ,Selenocysteine and selenomethionine were separated by HPLC connected to a graphite furnace by a laboratory made interface for detection by AAS IOrganoselenium compounds were digested by HNO and H,O,. Electrothermal atomization of the digestate was accomplished with a Pd chemical modifier AA;Hy;L AA;ETA;S Samples digested with HNO, were diluted with See Cu ref. Reference ranges were presented for groups in different countries methods of analysis year of study etc.,.The authors suggest that concentrations reflect dietary intake 'The gaseous hydride was collected in a heated silver- coated graphite furnace. The temperature was raised to °C for atomization Separation of selenomethionine selenocysteine SeIV and Se"' in samples from individuals given Se and *,Se was effected by HPLC coupled to ICP- MS ]Blood was diluted with H andTriton X-. The modifier,.% Ni-O.% Pt was added in the furnace as a separate injection. For serum the dilution was made with Ni-Triton X-. Standard additions was used for calibration and D background correction was applied. Accuracy was demonstrated by analysis of a CRM !$ee As ref. !See As ref. Aqueous samples were treated with KBr,-KBr-HC and min UV irradiation for digestion. HCI was added and then % NH,.OH*HCl to remove yellow colour. Tissues were digested at "C with HN,-HClO, HCl and NH -H.HCl were then added. Solutions were boiled and then taken for HG which was collected in a liquid N trap. No interferences were observed Acidified urine,. ml was mixed with p each of Pd. mg ml-' Mg. mg ml-' and Ba. mg ml. pl were injected into the furnace. Recoveries of added Se were >% and good results were obtained with an SRM AA;Hy:L MS;ICP;L AA;ETA;L MS;ICP;L A A;H y; L A A;H y ;L A A; ETA; L Reference C c C R Journal of Analytical Atomic Spectrometry April Vol. Table continued Element MatrixTechnique; atomization; Sample treatment comments Se Se Se Se Se Se Se Se Se Se Se Se Se Se Se Se Tissues Biological materials AA;ETA;L AA;ETA;Sl Biological materials Clinical samples Serum Biological tissues Urine Biological materials Biological samples Plasma Serum Plasma Biological samples AA;Hy:L A A; ETA; L AA;ETA;L AA;ETA;L AA;H y;L MS;MIP;L MS;ICP;L A F; H y ; L AA;ETA;L Se Heart AA;ETA;L - mg tissue was lyophilized and then dissolved with HNO,. Triton X- was added and a portion injected into the graphite tube with Pd-Cu pg and. pg respectively for measurement of Se.The Se status was assessed in patients receiving long- term home parenteral or enteral nutrition in Japanese Se was measured in breast milk of women from Niger. Concentrations decreased for up to months post parturn and were unrelated to maternal serum Se levels Digestion in H,SO, H,O and V-H,SO at °C was as effective as an IUPAC reference procedure. Good results were obtained for CRMs. Samples from children in Austria had lower Se concentrations than found in other European countries Plasma A A;Hy;L Breast milk serum A A;ETA; L Whole blood serum urine AA;Hy;L See Al ref. - g was digested with ml HN,-H,O + in an autoclave at "C for h. The solution was adjusted to pH. and heated for min with - mg Polyorgs YIIM sorbent.The sorbent was filtered washed and suspended in H,O to provide the sample for analysis with an LOD of. pg -' Reduction of SeV' to Se" was investigated to develop a robust reliable method for this critical step. Heating with HCI in closed containers was shown to be effective without loss of volatile Se and independent of time for up to h Hydroxylamine hydrochloride was added to reduce the Pd chemical modifier and to avoid precipitation of protein which occurs with Pd-ascorbate photomultipliers and chemical modifiers to improve measurement of Se were described were evaluated as chemical modifiers for use with different Se species. A complex series of interactions was described. Pd provided for greatest thermostabilization inclusion of MgNO increased the signal but reduced the thermostabilization.The recommended modifier was. pg Pd-. pg Mg Developments with hollow cathode lamps Cu Pd and Ni as nitrates alone and in combination See As ref. In an ID assay the isotope ratio Se:Se was measured with good precision by using a long integration time. Interference from SO + at m z = was found but was not a problem because of the low concentrations Several Se compounds in specimens were separated by SEC with ICP-MS detection at m z and. The natural abundance of these isotopes was dependent on dietary intakes Low plasma Se concentrations in subjects living in Scotland were reported Pd-ascorbate or Pd-MgNO were used as chemical modifiers to measure Se in specimens from residents of different regions of the Czech Republic in a study of cardiovascular disease See Cu ref. Factors involved in the digestion of samples with microwave heating volumes of HNO and HS microwave power and time were optimized using a three-level orthogonal array design.The general principles were applied to the measurement of Se in biological samples. With. g powdered SRM it was found that optimum conditions were to use. ml HNO,,. ml H,S and % microwave power for min Reference c c c J C J Journal of Analytical Atomic Spectrometry April VoZ. R Element Matrix Se Follicular fluid serum AA;ETA;L Si Plasma urine Si Biological materials Si Whole blood Si Serum Sn Biological tissues Sn Sn Blood Tissues Sn Biological samples Sn Urine Sn Urine Sn Biological tissues Sn Biological tissues Sr Serum Sr Whole blood Sr Mammoth bone Sr Tooth enamel Te Urine Te Biological specimens AE;DCP;L AE;ICP;L AA;ETA;L AA;ETA;L AA;ETA;L A A;ETA;L AE;MIP;L AA;-;L AE;F;L AA;Hy;L AA;H y;L AE;MIP;L AA;ETA;L AE;ICP;L AA;F;L AE;F MS;GC;L N,O-CzH,;L AA;ETA;L AA;Hy:L Sample treatment comments Concentrations of Se in follicular fluid were approximately % of those in serum. Low levels were found in samples from subjects with unexplained infertility.The method had an LOD of. pg ml-'. Reference ranges for healthy individuals were presented <.- pg ml-I and <.- pg ml-' for plasma and urine respectively See Al ref. Ca was used as the chemical modifier and the furnace was coated with tungsten. Matrix matched calibration solutions were employed in Chinese See Al ref. Total Sn levels were determined after acid digestion and removal of dissolved solids by ion exchange. Organotin compounds were extracted into heptane from acid-homogenized tissue and the mono- and dibutyltin species removed by backwashing with. mol -' NaOH.Tributyltin was taken into methanol-HNO and the Sn measured in a tungsten-treated graphite tube. The LOD for tributyltin was. ng g-' HP and % of ascorbate improved the sensitivity of the analysis and the LOD was. ng ml-' with pl of sample homogenized samples with acidified ether. Silica gel chromatography was used to clean the extract and the organotin reacted with methylmagnesium bromide to form tetraalkylated organotin species which were separated by GC with MIP-AES detection Sn from digested samples was extracted into IBMK and measured by AAS and NAA. There was good agreement between results from the two techniques Organotin compounds were reacted within GC sampling vials to produce volatile hydride species which were separated by GC with flame AE detection A chemical modifier with pg ml-' of Ni,. % of Organotin compounds were extracted from See As ref. - g tissue were solubilized with - ml of % m mTMAH for - min at °C. After adjustment of the pH to ml of hexane and ml of sodium tetraethylborate were added. The samples were shaken for min the organic layer taken reduced under N to ml and pl injected onto a GC column to separate the organotin compounds. The detector was a quartz tube furnace heated with an H,-air flame and the LOD was pg Solubilization of samples with TMAH was compared with enzymic digestion for initial preparation. Derivatization was with sodium tetraethylborate for capillary GC with MIP-AES for separation and detection of organotin species See Ge ref. Samples were digested by microwave heating and analysed with no further treatment.The LOD was. pg -' and normal values were around. I-' See Cu ref. The sample was prepared to contain K at ppm A Te complex with Li to correct for ionization interference bistrifluoroethy dithiocarbamate was prepared from digested samples and reacted with -fluoropheny magnesium bromide. "'Te was added for internal standardization. The TeC,H,F was determined by GC-MS and results were similar to those given by ETAAS See Se ref. lC Reference lC lC R Journal of Analytical Atomic Spectrometry April Vol. Table continued ~~ Technique; atomization; AA;ETA;Sl Sample treatment comments Te"' in digested samples was reduced by HCl and the Te'" separated by ion-exchange. In a novel analysis a suspension of the resin and NiN was injected into the graphite furnace in Japanese An LOD of ng g-' was achieved in a study to monitor pulmonary exposure to monoazite Samples were mixed with.% HNO and.%Triton X-. Additions of Ti were prepared for internal calibration. A long heating programme was developed to give careful drying and avoid losses of Ti and to prevent accumulation of ash in the tube. The LOD was. ng ml-' See As ref. C See Hg ref. - An LOD of ng g-' was achieved in a study to monitor pulmonary exposure to monoazite Specimens were diluted + with. mol -' HNO and the LOD was reported to be pg -' in Spanish See Al ref. C V in prepared solutions was complexed with -hydroxyquinoline and adsorbed on charcoal to effect enrichment of concentration for measurement by FAAS Samples diluted -fold with.% v vTriton X- and analysed using pg -' Pd-% m v citric acid-. mol -' HNO as the chemical modifier. Increased concentrations were found in patients with chronic renal failure See Ag ref. Reference C C Element Te Th Ti T T U V V V V Zn Zn Zn Zn Zn Zn Zn Zn Matrix Urine Faeces Serum MS;ICP;L AA;ETA;L MS;ICP;L MS;ICP;L MS;ICP;L A A;ETA;L Blood urine Hair Faeces Plasma Plasma Tissues urine AA;ETA;L AA;F;L Plasma AA;ETA;L Lobster digestive gland AA;F;L AE;ICP;L AA;F air-C,H,;L AA;ETA;L.-_ AA;ETA;L Urine Biological samples Serum blood ultrafiltrate See Al ref. See Cu ref. Blood was digested with HNO and HS followed by heating with H and the addition of H. Serum was similarly prepared but without addition of H,O,. ETAAS was required for measurement of Zn in diluted ultrafiltrate See Cu ref. See Pb ref. See Cu ref. Plasma Zn levels at intervals after an iv injection of Zn were determined. Samples were digested with H the Zn extracted with.% diethylammonium DDC in CCl and then back- extracted with HNO,. Zn:Zn ratios were measured by MS in Japanese See Cu See Cu ref. LiverTissues Tissues Plasma AE;ICP;L AA;-;- AA;-;- MS;ICP;L Zn Zn Plasma Plasma blood cells AA;F;L AA;F;L AA;F;L AA;ETA;L Zn Plasma Day-to-day variation in subjects aged - y was about % which was greater than reported for younger individuals sedimentation were lysed by sonication. Reference values expressed as pg per " cells and as pg g-' protein were given in Japanese Leucocytes separated from blood by dextran See Al ref. See Mg ref. See Cd ref. See Ca ref.This work is described in more detail in Various See Cu ref. Liver homogenates in mol -' HCl were subject to ref. less matrix interference than other media investigated centrifuged. pl of supernatant was taken for pulse sampling FAAS to determine the 'uncombined' Zn in Chinese. ml serum +. ml saturated NH S was See Cd ref. Dermal absorption of Zn from ointments was investigated Zn Leucocytes AA;F;L Zn Zn Zn Zn Zn Tissues Choroid-retina Tissue Urine faeces Stomach intestine AA;ETA;L AE;ICP;L AA;ETA;S MS;ICP;L MS;ICPL AA;ETA;L AA;F;L Zn Zn Plasma blood cells Liver AA;F air-CH;L Zn Serum Zn Zn Skin Skin sebaceous glands Journal of Analytical Atomic Spectrometry April Vol. I R Element Matrix Zn Whole blood AECP;L Zn Plasma urine AA;ETA;L Zn Breast milk AA;F;L MULTI-ELEMENT ANALYSIS Serum plasma and blood Various Placental serum AE;ICP;L Zn Plasma AA;-;- Various Blood MS;ICP;L Various Whole blood urine milk AE;ICP;L Various Serum Various Whole blood Various Serum Various Serum CSF Various Blood urine bone Various Serum biological materials Various Serum Various Urine plasma erythrocytes Various Plasma bone Various Serum AE;ICP;L AA;F;L AA;H y:L AE;ICP;L AA;ETA;L AA;F;L AA;ETA;L MS;ICP;L MS;ICP;L AA;F;L AA;ETA;L M S;MI P;L MS;ICP;L AA;F;L Sample treatmentJcomments See Ca ref. See Cu ref. See Cu ref. See Fe ref. Serum+ ml HNO was cooled in a refrigerator. After addition of ml HNO the solution was heated until clear. HClO, ml was added and the sample heated almost to dryness.The residue was dissolved in ml of. mol - HC and diluted to ml with H. Recoveries were -% in Chinese Spectral interferences were abolished by use of high resolution sector field ICP-MS for the measurement of platinum group metals and Au sequentially mixed with HNO HN,-H,SO and H,O for digestion with an open focused microwave system.The digestion sequence could be programmed to provide optimized conditions for each sample matrix Serum ml was heated with ml HNO and. ml HClO, the solution evaporated almost to dryness and diluted to ml with H,O Ca Cu Fe K Mg Na P Zn in Chinese Samples from patients with Blackfoot disease were digested with acid and elements measured As Cu Fe Se Zn A mixture of sample and sodium acetate-acetic acid buffer mol I-' pH. was pumped though a desolvation device coupled to an on-line column of -hydroxyquinoline-sulfonic acid on an active carbon-silica gel support.The analytes were eluted with mol -' HC. The desolvation efficiency was % and the column could be used more than times. Detection limits were.-. ng ml-' Al Cd Cu Fe Mn Concentrations in specimens from subjects without neurological disorders were determined Al Cu Mg Mn Pb Zn in Greek Blood was diluted with.% Triton X- urine with.% Triton X-. mol -' HNO and digested bone with. mol -' HNO,. Chemical modifiers placed into the graphite furnace were used for measurement of Pb. mg -' Pd-% m v citric acid and V. mg -' Pd-% m v citric acid-. mol -' HNO,. Detection limits were.-. pg - and accurate results were obtained with a series of CRMs Al Cu Fe Pb V 'The author reviews ICP-MS for the determination of trace elements in biological materials It was shown that serum-separating tubes and stainless-steel needles caused increased concentrations of elements. Samples were diluted -fold with H,O 'The effect of desferrioxamine on mobilization and urinary excretion of metals was investigated. A new approach to the treatment of Pb toxicity was proposed Al Ca Fe Mg Pb contamination among reagents sample tubes etc. and for matrix effects on the analytical results in Japanese Interferences in the simultaneous measurement of elements by ICP-MS were examined and results compared with those given by FAAS. Problems were found for the determination of Ca and Mg but matrix-matched calibration or standard additions gave acceptable results Br Ca Mg Rb Sr Zn In a continuous FI arrangement the sample was Zn.The authors sought for possible sources of ~~ ~~ Reference C R Journal of Analytical Atomic Spectrometry April Vol. Table continued Element MatrixTechnique; atomization; MULTI-ELEMENT ANALYSIS Urine faeces Various Urine AEDCP;L Various Whole blood urine milk AEICPL Various Blood urine bone A A;ETAL Various Urine plasma erythrocytes AA;F;L Various Faeces M S;ICP;L AA;ETA;L MULTI-ELEMENT ANALYSIS Other biological fluids Various Whole blood urine milk Various Serum CSF Various Sweat MULTI-ELEMENT ANALYSIS Soft tissues Various Soft tissues bone Various Biological tissues Various Kidney Various Brain Various Placenta Various Kidney Various Biological tissues Various Tissues Various Tissues Various Tissues AE;ICP;L A A; ETA; L AA;F;L AA;F;L AA;ETA;L AA;F air-C,H,;L AE;ICP;L AA;CV;L AE;ICP;L AE;ICP;L A A;ETA;L XRF;-;S MS;ICP;S AE;ICP;L MS;ICP;L AE;ICP;L Sample treatment comments.The As K Na and P affected the spectral emission of other elements and matrix-matched calibration was employed to give accurate results See Serum plasma and blood ref. See Serum plasma and blood ref. See Serum plasma and blood ref. Vacuum-dried faecal samples were dry ashed in platinum crucibles. The ash from g was dissolved in ml HNO and diluted to ml with H,O. Isotope ratios were determined and precisions of <O.l o RSD were achieved for all elements except Li. The low RSDs were obtained by using long count times - min and by counting isotopes which are within a factor of ten in abundance. Drift was compensated with a third isotope by addition of two internal standards or by frequent recalibration Cu Fe Li Ni Pb Zn See Serum plasma and blood ref. See Serum plasma and blood ref. Substantial quantities of trace elements were found in sweat Al Cd Cu Mn Ni Zn Samples were digested with HN,-HClO in a closed vessel Ca Cu Fe Mg Zn in ChineseTissues were ashed at OoC % H,O added and the solution evaporated to dryness. After a second ashing step the residue was dissolved in HCl and diluted with H,O. Further samples were digested with HNO and HClO for measurement of Hg by CVAAS -.-fold was accomplished using the chelating agent M-Tetrakis-aminopheny porphyrin and carbon-silica gel. Analytes were eluted with NH,-H,O-NH,C at pH. Cd Cu Fe Mn Ni Pb in Chinese Concentrations of elements in regions of the brain were determined in specimens from individuals with Alzheimer's disease. Specific distribution patterns associated with A and Zn were identified Digestion procedures were investigated and either HNO in a pressure bomb or HN-H were considered suitable. Concentrations were very high in specimens collected in an area with increased environmental exposures Cd Co Cr Cu Mn Mo Pb Zn Concentrations of trace elements in tumour-bearing animals were measured after injection of cisplatin with or without selenite and selenocystamine Cu Fe K Pt Se Zn Distribution of elements with a spatial resolution of pm was determined in fish scales rat kidney and pig femur Small samples of tissue - mg were placed into a quartz container within a high-pressure digestion vessel containing acid. Heating led to vapour- phase acid digestion.The technique showed good recoveries and low blanks C Ca Cd Cu Fe Mg Mn Zn.Their tissue distribution and the perturbation of essential elements were determined Normal concentrations were measured in rat organs from animals aged and weeks. Specimens were prepared for analysis by lyophilization and digestion with HNO -HC in Japanese On-line preconcentration with enrichment of Mixtures of REEs were administered to mice. Journal of Analytical Atomic Spectrometry April Vol. ~ Reference R Table continued Element Matrix Technique; atomization; Various Brain AE;ICP;L Various Tissues intestinal contents MS;ICP;L Various Gelatin films MS;-;S Various Tissue biopsy samples MS;-;S Various Brain AE;ICP;L Various Tissues AE;ICP;L AA;ETA;L AA;CV;L MS;ICP;L MULTI-ELEMENT ANALYSIS Bone and other hard tissues Various Bone teeth AA;F;L Various Soft tissues bone Various Blood urine bone Various Dental plaque Various Calcified tissue Various Plasma bone Various Bone VariousTeeth AA;F air-C,H,;L AA;ETA;L XRF;-;S MS;ICP;S MS;MIP;L AE;ICP;L MS;ICP;S MULTI-ELEMENT ANALYSIS Hair nails Various Hair AE;ICP;L Various Hair biological samples Various Hair Various Hair MS;ICP;S X R F;-; S AE;ICP;L AA;ETA;L Sample treatment comments Concentration changes in mouse brain after repeated hypoxia were investigated As B Co Cr Cu Fe V in Chinese uptake from foods assimilation and incorporation into tissues were examined Al Cu Mn Ru Sr Zn Porcine gelatin films were spiked to different concentrations to use as model systems for SIMS analyses analysis were discussed HNO in a digestion bomb in a microwave oven. The digestate was made to ml with H for ICP- AES. Nine brain regions were examined to provide normal reference data Al Ca Cu K Mg Mn Na P S Sr Zn Dried tissue samples were digested in PTFE bombs using HN,-H. Fresh and formalin-fixed tissues were compared. A increased in fixed tissues after and months storage while small decreases in Mn were seen. Normal concentrations were reported for areas of brain from human subjects Al As Ca Cd Cu Fe Hg Mg Mn Pb Zn Methods of sample preparation to improve SIMS LOO mg of brain otissue was heated with ml of Samples ashed at "C were then microwave heated in a bomb for s.This permitted the simple preparation of large samples without contamination Ba Ca Cd Fe K Mg Na Pb Zn See Soft tissues ref. See Serum plasma and blood ref. Microgram-sized samples of dental plaque from different parts of the mouth were investigated byTXRF Trace elements in otoliths coral and fossilized bone were used to monitor environmental changes. With laser ablation sampling very fine spatial resolution across solid samples was achieved Ba Cu Li Mg Pb REEs Zn See Serum plasma and blood ref. The composition of prehistoric human bones were determined to investigate environmental conditions nutrition and migratory behaviour Ba Ca Cd Cu Pb Sr Zn have important influences on the LA process. The amount of Ca ablated and species differences in tooth composition also affected the signal. Careful attention to these variables was crucial to achievement of reproducible accurate results Laser energy and pulse frequency were shown to Hair samples were digested with HNO and HClO,. The HC concentration and ascorbate in the NaBH solution were optimized for HG. With. mol - HCl and.% ascorbate in YO NaBH the LODs were from.-. ng ml-' As Ge Hg Sb Se Sn in Chinese A free-running ruby laser was used to vaporize solid samples directly into the plasma. Accuracy and precision were inferior to pneumatic nebulization but rapid semi-quantitative results were obtained Washed hairs were dried and individually mounted for longitudinal SEM and for nuclear scanning PIXE of transverse sections Al Ca Fe K Mg Na P S Si Zn. g of hair was heated at "C for min with HN,-HClO :. Se was measured by ETAAS other elements by ICP-AES and differences were seen between specimens from patients with cancer and healthy subjects Reference. c R Journal of Analytical Atomic Spectrometry April. Table continued Element MatrixTechnique; atomization; MULTI-ELEMENT ANALYSIS Biological materials RMs Various Biological materials AA;-;L.__- Various Clinical and biological samples Various Biological materials AA;ETA;L Various Hair biological samples MS;ICP;S Various Biological materials M S;ICP;L Various Serum biological materials MS;ICP;L Various Biological materials MS;ICP;L MS.-.- Various Biological materials ? Various Amphetamine drugs AE;ICP;L MS;ICP;L.-_- Various Clinical and biological samples Various Potential allergens XRF;-;S Various Biological samples MS;-;- Various Clinical samples AFi-i-.-_- Various Biological materials Various Biological materials XRF;-;S Sample treatment comments A rapid simple acid digestion procedure was developed which used ultrasonic energy to promote the destruction of biological samples Cd Cr Cu Fe Mn Ni Pb Zn in Spanish.The ASU which reviewed analytical developments during the previous year Continuum source AAS was described with instrumentation which included an Echelle monochromator and a linear photodiode array detector. Detection limits were similar to those achieved with conventional systems Cd Cr Cu Mn Mo Pb See Hair nails ref. Dried sample mg was placed with ml HNO in a PTFE double-vessel digestion bomb.The bomb was heated in an oven at "C for h and then at "C for h. When cooled the inner container was removed and heated gently to release NO As Ge Mo Ni V Zn in Japanese See Serum plasma and blood ref. The authors review ICP-MS for the determination of trace elements in biological materials in Japanese An extensive review of different MS techniquesTIMS ICP-MS FAB-MS GC-MS and the use of ID for the measurement of trace elements in biological samples Powdered pharmaceutical was dissolved in diluted HNO,. The ASU which reviewed analytical developments during the previous year. Items suspected of contributing to dental allergies were analysed for the presence of metals known to be allergenic Ag Au Cr Cu Fe Hg Mn Ni Pd Sn Zn in Japanese A comprehensive review of MS methods which are used to measure stable isotopes for trace element balance studies A new instrument was described which featured high intensity light sources high throughput optics high signaknoise ratio and HG. The LODs were at pg ml-' levels and few interferences were experienced As Bi Cd Ge Hg Pb Sb Se Sn Te Zn chromatographic approaches with detection by atomic spectrometric techniques were discussed Al As Hg Si Sn micro-XRF and the work of a European facility at Grenoble were described Strategies for speciation involving novel.The potential of synchrotron radiation induced Reference c J c * Hy indicates hydride generation and S L G and S signify solid liquid gaseous or slurry sample introduction respectively. Other abbreviations are listed elsewhere. ANALYSIS OF FOODS AND BEVERAGES Simon Branch and Helen Crews presented by Haswell at the SAC conference in Hull in July C. A summary of the published and conference papers covered in this review is given in Table. The organization of this part of the review is similar to that presented last year. Elements which had a particularly high profile this year are As Se and to a lesser extent Al. In addition there has been an increase in papers from Poland other Eastern European countries and China. As well as the ASU review there has been a Japanese review of the analysis of heavy metals a review by Crews et al. on mass spectro- metric methods for studying nutrient mineral and trace element absorption and metabolism using stable isotopes and also an overview of sample preparation was. Sampling and Sample Preparation. Direct determination of analytes Simple dilution of a sample is currently the nearest that analysts can get to minimal sample preparation. Copper was determined in port wine and Madeira wine by ETAAS following a + dilution with.% HN.The calibration graph for Cu was linear in the range.- pg -' of Cu and the LOD for the undiluted sample was. pg I-'. Samples of wine alcohol aromatic alcohol apple and malt vinegars were analysed by FAAS for Cd Ni and Pb.The vinegars were evaporated to dryness and the white residue dissolved in Journal of Analytical Atomic Spectrometry April Vol. R diluted HC +. Detection limits were. ppm for Cd,. ppm for Ni and. ppm for Pb. Preconcentration Three different preconcentration methods for the determiviation of Cd and Pb in mineral waters were investigated by CujeS and Gorup C. The first method was based on coprecipi- tation with MgOH ,. The coprecipitate was dissolved in HNO and the analytes determined by ETAAS. Enrichment factors obtained were approximately for both Cd and Pb with LODs of. and ng ml-' respectively. The second method tested was ligand exchange liquid-liquid extraction using a DDC complex.The enrichment factors obtained were for Cd and for Pb with respective LODs of and ng I-'. Flame AAS was used for the determinations. The third method was on-line ion exchange enrichment using Chelex-. The measurements were carried out with FI-FAAS and enrichment factors of and were obtained for Cd and Pb respectively. The LOD for Cd was ng -' and for Pb. ngml-'. Saxena et al. determined both Pb and Zn using Amberlite XAD- for preconcentration prior to measurement by FAAS. The Amberlite was functionalized by coupling it through an -N=N- group with salicylic acid. The optimum pH values for quantitative absorption of Pb" and Zn" were - and respectively. The two metals can be desorbed with good recoveries -Y using HC-HNO and HCl for Pb and Zn respectively. The only interference found for Pb was PO,-.The preconcentration factors were found to be for Pb at the ppb level and for Zn at the. ppb level. Simultaneous determination of the two metals was possible and it was concluded that cations com- monly present in water did not effect the absorption of both metal ions by the resin. On-line preconcentration of A was investigated by Spanish workers. The method was based on selective retention of A in a micro-column packed with Chromotrope B immobilized on an X-AG ion- exchange resin. All the variables that affected the efficiency of A retention and dilution from the micro-column were investi- gated. For collection times of and min at a flow rate of ml min-' the LODs were and. ng ml-' for FAAS and ICP-MS respectively. The method was successfully applied to the determination of A in tap water and dialysis solutions. Flame AAS was used to measure A after preconcentration on various sorbents. Optimal results of -fold enrichment were obtained when less than or equal to pg A in. mol -'TRIS buffer pH was applied at ml min-' to a column packed with silica gel or Chrome Azurol S CAS - modified Amberlite IRA. The A was eluted with mol -' of HCl. Preconcentration using. mol -' malonate-NH buffer pH and. mol -' ammonium acetate pH. for the Amberlite and silica gel columns respectively was also satisfactory. The method was applied to potable water and renal dialysates. Albumen interference was decreased by the use of. YO Triton-X,.% polyviny pyrrolidone and.% trypsin. IronI interfered with determinations using Amberlite. Trace Mo in tap water was measured after on-line ion exchange preconcentration with an FI-ICP-AES system.The water was injected onto a micro-ion-exchange column packed with Dowex- resin with NH,Cl-amrnoriium citrate as the eluent at. ml min-' at °C over min. Recoveries were -% for. ng ml-' of Mo and the RSD was.%. An enrichment factor of was achieved at sampling frequency of samples h-'. Leng measured Cu Fe Mn and Zn in tap water following adjustment to pH. with HCL and or NH,. The water was mixed with APDC-DDC and shaken with IBMK-xylene after which the organic phase was shaken with HNO and finally the aqueous layer analysed by FAAS. A rapid method for the determination of Cd in soya sauce in which APDC was used as precipitant was described by Su et al. Cadmium determination was by FAAS. No interference by any other element was observed.The recovery of Cd was -% with a linear calibration curve in the range -. mg Cd -' at pH. The s for measurements was.%. An enrichment method was developed for the determination of Cd and Pb in vegetable material using FAAS after preconcentration with -hydroxyquinoline or cupferron on activated carbon. An enrichment factor of up was achieved by using both of the complexing reagents. The optimum lowest pH values were found to be. and. with cupferron and. and. with -hydroxyquinoline for Cd and Pb respectively. The RSDs were % for Cd at pg -' and % for Pb at pg -'. Vegetable samples from fertilized farmland and roadside areas of Zucchetti in Turkey were analysed using this method. Digestion Dry ashing or wet ashing with various acids are the most common methods for sample destruction. Zucchetti and Contarini have investigated the use of trichloroacetic acidTCA for the analysis of solid matrices such as cheese. They used TCA to extract Ca K and Na. The percentage recovery was evaluated using standard solutions and a milk powder RM. Trials were also carried out on milk and cheese spiked with cations. The percentage recovery ranged from. The influence of digestion methods on the determination of A in food samples by ICP-AES was investigated. The authors state that to determine total A in a variety of food and total diet samples pretreatment with HF prior to wet digestion with HN,-HClO, seemed to be necessary. When the results obtained after HF pretreatment were compared with those obtained using microwave digestion with HNO or HN,-HClO, the latter acids recovered only -% of the A from dried spinach and flour and -% from total diet samples. In most cases the addition of. ml of HF per gram of dry mass resulted in a maximum A yield.The results were found to be in acceptable agreement with those obtained by NAA. The use of closed vessel microwave acid digestion has been described by a group of workers looking to optimize trace A determinations in foodstuffs. The estimation of daily dietary intake of A was part of an ongoing project aimed at the assessment of the daily intake of food constituents by the Belgian population. The method to be applied to different solid foods was that of dissolution of the samples with microwave digestion using HN-H with subsequent A determination by ETAAS. The use of closed-vessel micro- wave acid digestion was found to shorten the time for sample dissolution and to improve the analytical quality. Direct calibration against aqueous solutions was used for all of the digests. Aluminium was determined in different types of bread and types of fish with an LOD in solution of approximately pg -' s.The use of closed-vessel microwave acid digestion has been described by a group of workers looking to optimize trace A determinations in foodstuffs. The digestion procedures used for multi-element analyses of milk by ICP-MS were compared by Alkanani et al. The elements As Cd Cr Cu Mg Mn Mo Ni Pb Rb and Zn were determined in IAEA CRM A- milk powder in human breast milk and in a representative variety of infant formulae. The effects of digestion procedures and the masses of the reference milk samples on the recovery precision and accuracy of multi-element analysis for milk were examined. to.%. R Journal of Analytical Atomic Spectrometry April. Both high-pressure microwave bombs and four closed vessel ashing procedures were used as the means of digestion. Elements were either preconcentrated on a Chelex- resin or determined directly in a diluted digest.The most satisfactory results were obtained using closed vessel ashing on a hot-plate and direct analysis of the diluted digest. The optimum pro- cedure consisted of heating the milk with HNO in a sealed vessel at °C for d. This seems an awfully long time to digest a sample. It is surprising that high-pressure microwave digestion was not able to reduce this sample digestion time as found for A in above. Negretti De Bratter et al. have used microwave-based digestion for the deter- mination of macro- and trace elements in total diet samples with determination by ICP-AES.They have compared a microwave-based digestion with pressurized ashing systems using different acid mixtures. They found the most reliable digestion procedure for the determination of Al Ca Cu Fe K Mg Na P and Zn in total diet samples using ICP-AES was a microwave-based technique using HNO alone or with a mixture of HN,-H,O +. In comparison the pressur- ized ashing technique was faster but lower values for K were obtained. In the end the authors chose the pressurized ashing technique using HN,-H,O to perform the digestion on total diet samples because it was simple and rapid. In a conference presentation C focused open and closed vessel microwave digestion procedures were compared with conventional digestion procedures for the trace element analy- sis of cereals.The authors stated that of the various sample preparation techniques available microwave digestion was increasingly the method of choice with the advantages of reduced sample preparation time reduced consumption of acid and the ability to control the conditions for flexibility in digestion methods. Systems were evaluated using cereal CRMs from Canada the United States of America the EC Japan and China as well as in-house quality control cereal samples. We look forward to seeing this work in publication. The determination of Ca K Mg and Na by FAAS was described for milk samples following microwave oven digestion. Milk was mixed with HN,-H,O in a PTFE vessel. Lanthanum as LaCI was added.The mixture was heated in a microwave oven both domestic and analytical microwave ovens were used by irradiation at W for min and then at W for min. The digests were cooled and diluted Ca and Mg were determined by FAAS and K and Na by AES. Quantification was by external calibration except for Ca in whole milk for which standard additions were used. The LODs were and pg -l for Ca K Mg and Na. The RSDs n= were -% for all four elements and recoveries were quantitative. Results agreed with those obtained by using a sample preparation procedure involving precipitation with TCA see also reference in. The authors concluded that the microwave oven digestion method was very practical for routine laboratory analysis of relatively large numbers of samples.Two papers describe the use of microwave dissolution for the determination of trace metals in seafood products. Cabrera et al. have determined Cd in seafoods frequently consumed in Mediterranean coastal regions of Spain. The method was tested using CRMs from the EC and an LOD of. pg was reported. The highest concentrations of Cd were found in crustaceans and cephalopods with the maximum concen- tration reported being. ng g-'. Sheppard et al. determined As Cd and Pb in seafood products by ICP-AES and ICP-MS. A single microwave digestion procedure was used with a variety of products including tuna salmon shrimp walleye clams oysters and lobster. The precision for replicate analyses of clams was.% for As at the pg g-' level,.% for Cd at the. pg g-' level and.% for Pb at the. pg g p l level. Results for two CRMs were in good agreement with certified values.The homogenized seafoods were mixed with concentrated HNO, allowed to pre-digest for min after which microwave digestion was used. A six- stage pressure programme was employed. In the final stage the microwave power was decreased to zero over min and then kept at zero for a further min. A slight modification to the procedure was made for lobster. Direct solid and slurry sampling In a conference presentation C Fonseca and Miller- Ihli described the advantages of solid sampling over traditional sample preparation procedures. The most notable advantages are the avoidance of time consuming sample preparation procedures and the minimized risk of sample contamination. They describe a study in which ultrasonic slurry sampling ETV- ICP-MS was used for the determination of Cu Mn Ni Pb and V in a diet sample and in oyster tissue.They discussed different calibration strategies and the benefits and limitations of this technique. Compromise conditions for metal element determinations were considered focusing on furnace con- ditions including the use of and ashing. The beneficial effect of using tygothane tubing was verified in this work as a means of improving transport efficiency. Again we look forward to seeing this important work published. Aluminium was determined in milk dessert samples by ETAAS. The aim of the work was to avoid sample weighing dilution and homogenization by preparing milk dessert slurries. A preparation module allowed aqueous stan- dards to be automatically inserted in such a way that cali- bration could be implemented without sample weighing.The module was coupled to the instrument's autosampler. The module consisted of an FI system connected semi-on-line to an ETAAS system through an autosampler for preparation of the slurries addition of chemical modifier and dilution-homogeniz- ation in a mixing chamber. Calibration was performed with aqueous standards. Slurries contained up to % m v. Aluminium was determined in various milk desserts at concentrations between. and. mg per g. A series of papers by Vinas and colleagues describe the use of slurry procedures with E TAAS for determining trace elements infoodstufls. The determination of Cu Cr Fe Pb and Zn in sweets and chewing gum after partial dry ashing was described in the first of this series.The samples were heated at °C for h and the resulting residue was ground and made into a slurry by mixing with an C,H,OH-H,-NHHP mixture. The stirred suspension was analysed by ETAAS using fast programme methodology in which the drying and ashing stages were replaced by a modified drying stage. The NH,H,P was added as chemical modifier and the H was added to prevent the build-up of carbonaceous residues inside the atomizer. Calibration was carried out using aqueous standards and the reliability of the procedure was ascertained by analysing several CRMs. The RSD of the method ranged from.% for Fe to.% for Zn. The LOD was ng g-' for Cr for Cu for Fe for Pb and for Zn. In a second paper slurry procedures for determining Cd and Pb in cereal-based products were described. Again the method- ology required C,H,OH H and chemical modifiers. For Cd Pd and an ammoniacal Cu" solution was used. For Pb PO- was used as the modifier. For these samples fast programme methodology was not used and the drying char- ring and ashing temperatures were and °C for Cd and and "C for Pb.The LODs and percentage S were. ng g-' and.-.% for Cd and ng g-' and.-% for Pb. Again the method was validated with two RMs and the method finally applied to biscuits bread and other cereal-based products. Copper was also analysed in these types of sample but for this element fast programme Journal of Analytical Atomic Spectrometry April Vol. R slurry ETAAS was used. There was no significant difference in calibration response between aqueous standards and matrix- matched standards for Cu and hence aqueous standards were used. Results for two RMs rice flour and wheat flour and samples of bread and biscuits were in good agreement with certificate values and with an independent AAS method of analysis. In the fast programme methodology the drying and ashing steps were replaced with a modified drying stage. Atomization was performed at "C and a clean-out step was not necessary. For slurry atomization of vegetable samples Vinas et al. washed the samples with water chopped and dried them to constant mass at °C. After grinding for min they treated - mg of the ground material with an CHH-H-NHHP mixture and made up to volume ml with H. Suspensions were homogenized and then continuously stirred for sampling by ETAAS. Again fast programme methodology was used. Results were in good agreement with those obtained by acid decomposition and also a slurry-based procedure using partial calcination of the samples but the RSDs were lower for the slurry atomization method. Finally rapid procedures for Co and Ni determination in slurried food samples was described by Vinas et al. Seafood samples were freeze-dried for h and then ground. Plant materials were washed chopped and dried before being ground. In this instance samples were diluted to ml with.%Triton X-% H-l% HN. Fast programme methodology was not used. Measurements were made at. and nm for Co and Ni respectively. A mild calcination procedure was used for materials containing very low Co concentrations.The LODs were and ng g-' for Co and Ni respectively. The corresponding RSDs were. and.% using a % slurry concentration. Solid sampling of spaghetti for the direct determination of Fe was described by Anzano and colleagues. Spaghetti fragments were weighed and handled with stainless steel tweez- ers. Sample masses of - mg were deposited directly into the pyrolytic graphite tube through an inverted paper cone with a pierced apex that was inserted into the enlarged hole of the tube. Iron was measured at. nm.The analytical conditions used permitted the determination of Fe at a concentration of pg g-' in pasta using aqueous standards for calibration. No special sample introduction system platform background noise correction or matrix modification were required. The RSD for the results was typically %. The direct analysis of solid samples by ETAAS was described in a second paper on this subject in this case focusing on the determination of Cd.The method was applied to the direct analysis of plants and cereals as well as soils and sediments. Dried sample was ground and mixed with matrix-modifier containing CaNO-LaNO,-NHNO-CHH. The sample was then dried again and applied with the use of a laboratory-made micro-solid sample injection device for L'vov platform ETAAS. With the use of standard additions recoveries were to % with RSD of.- %. No interferences were reported for this methodology. Flow injection FI-HG-AAS with on-line microwave digestion was used to determine Pb in wine beverages and fruit slurries. The lead hydride was generated in HN-H medium using NaBH as the reducing agent. For the determi- nation of Pb in beer juice and fruit a microwave oven was coupled on-line to the FI-HG-AAS system. For fruit the Pb hydride was generated from slurries of the fresh sample.The method enabled a direct determination of Pb in untreated samples with use of an aqueous calibration graph. No matrix interferences were found. The LOD was pg -' in wine and for other beverages or fruit the LOD was ng. An FI system incorporating a microwave oven was used for the digestion of food samples for subsequent determination of A by ETAAS. Sample slurry was simultaneously injected with HNO and transferred into a PTFE reactor coiled around a Erlenmeyer flask filled with H located in a microwave oven. The digested sample and flushing solution were collected in a autosampler cup. The performance of the method was evaluated by determining A in shellfish which typically contains abundant organic matter. Recovery of A was about % with no apparent differences between replicate analyses. An on-line method with FI was used for an adsorption and preconcentration method using a PTFE reactor with FAAS. Copper-DDC chelate was adsorbed onto the walls of a PTFE knotted reactor.The species were eluted by IBMK at a flow rate of. ml min-'; an enhancement factor of and an LOD of. pg -' were achieved for a s loading period. The sample throughput was samples h-'. An interference from Fe"' was eliminated by adding ascorbic acid. The method was successfully used for determining Cu in drinking water and rice. On-line preconcentration was also used in the determination of trace Pt by FI-FAAS. For on-line preconcentration on an alumina micro-column,. mol -l HN was used as the carrier solution.The adsorbed Pt was eluted by injecting ml of mol -' ammonia solution at ml min-l into the carrier stream. Recoveries for - pg I-' of Pt from spiked tap waters were greater than %. The method was suitable for the determi- nation of Pt in natural waters with an LOD of. pg -'. Speciation Studies. The bioavailability of A from infant formula compared with that from other milks including breast milk was described in a paper by Hawkins et al. The A was measured in samples of infant blood plasma and samples of feed obtained from infants with normal renal function established on various feeds breast whey based fortified whey based pre-term soya and casein hydrolysate. Blood samples were collected midway between feeds and A measured by ETAAS. Mean A concen- trations in milks were as follows breast,. pg -'; whey based,. pg -'; fortified pg -'; pre-term pg -I; soya yg -'; and casein hydrolysate pg -'.The mean blood plasma A concentrations in infants receiving the differ- ent milks were as follows breast,. pg -'; whey based,. pg -'; fortified,. pg -'; pre-term,. pg -'; soya,. pg la'; and casein hydrolysate,. pg -'. The mean plasma A concentrations for infants fed caesin hydrolysate formula were significantly different from those fed breast milk. The authors speculated that the A compounds found in breast milk were more bioavailable than those found in other milks and that some constituents of infant formulae affect A absorption from the gut lumen. In a conference presentation C the speciation of A in drinking water was described both in terms of the methods available and the significance of the speciation.The use of sampling kits to study on-site speciation was described. The methods were applied to laboratory and field studies particularly for surveys which targeted drinking water originating from untreated shallow groundwater or from treated surface water and groundwater. The significance of the results was discussed with regard to the potential toxicity of A species in drinking water and with regard to what speciation methods are required. To our knowledge this work has not yet been published and it would be of interest if it could be. Total and soluble Fe content and the eflects of various inhibitors present in selective varieties of bean Phaseolus acutifolius were evaluated. Tannins phosphates and oxalates affected the iron solubility in beans but it was not affected by crude fibre.The use of ETAAS for differentiating between organic and bound Fe was presented in a conference C. Again we look forward to seeing this work R Journal of Analytical Atomic Spectrometry April. published as iron speciation is becoming more important particularly in relation to the bioavailability of iron sup- plements in foodstuffs. Organic lead compounds in wine were determined by capillary GC with microwave induced PES. Ionic organolead compounds were extracted as DDC complexes into hexane and propylated with Grignard reagent. The derivatized extract was analysed by capillary GC and microwave induced PES. The method of standard additions was used for calibration. The most ubiquitous species was trimethyllead and wines made from grapes close to industrial zones showed elevated concen- trations of ethyllead species. Concentrations of methyllead and ethyllead found in wines were compared with the concen- trations of organolead found in rainwater and plant sap collected in the viticulture regions.The ratio of methyllead to ethyllead in wines greatly exceeded the same ratio found in atmospheric deposits. Larsen and Stuerup improved the LOD for As by a factor of. after the addition of CH,OH to aqueous analyte solutions which were subsequently measured by ICP-MS. In fact the addition of C as either CHH or NH ,C in combination with increased plasma power input enhanced single intensitiesfor As and Se. The addition of % v v CHH in the analyte solutions doubled the level of the background signal for both As and Se but the noise was not increased.Therefore the authors proposed that the observed increase in analyte sensitivity led to a similar increase in signal to noise ratio. In contrast the addition of C as NH C enhanced the As signal by a similar factor but also caused severe contamination of the ICP-MS instrument by C. In the % v v CH,OH solution of As and Se the signal intensity from Sb internal standard was enhanced by a factor of. This was taken to indicate that the enhancement effect on the As and Se signals by CHH was only due in a limited fashion to improved sample transport and nebulization efficiency. It was postulated that an increased population of C ions or C-containing ions in the plasma facilitated a more complete ionization of analytes lower in ionization energy than C itself. Enhanced detection power for As was applied to As speciation by HPLC-ICP-MS and made possible the detection of arseno- choline ion in extracts of shrimp at the -long g-' per concentration.The LOD was improved by factor. after the addition of CHH and was. ng g-' as the arsenocholine ion. The solubility of Cu Se and Zn in samples of mussels has been reported. Absorbable fractions of Cu Se and Zn from mussels were studied using in vitro techniques which simulated human gastric and intestinal digestion. The Se speciation study focused on the differentiation of protein ligands by H,O-TCA precipitation and gel-filtration chroma- tography. The in vitro absorbability showed that the major proportion of Cu Se and Zn was solubilized by the simulated stomach digestion and that at neutral pH the absorbable fraction of Cu and Se was almost the same while for Zn it was lower. A % decrease in absorbable Zn was observed after gastric and intestinal digestion.This was probably due to Zn precipitation either by PO- during the gastric stage or by other anions at the neutral pH of the intestinal stage. The Cu was determined in various factions by ETAAS Se was deter- mined by HGAAS and Zn by FAAS. Sanz-Medel et al. have investigated further the use of uesicle-mediated HPLC coupled to atomic detection for the speciation of toxic elements. In this publication the method was applied to the separation and determination of As species in tap water and urine. Also the use of surfactant vesicles as mobile phases for the speciation of As Hg Se and Sn was investigated. Separations were carried out on a CI-bonded silica reversed-phase column which was modified by passing didodecyldimethylammonium bromide DDAB solution in CH,OH at ml min-'.The column was flushed with H,O for min prior to use. Various mobile phases were used. The eluate from the column was mixed with HC-NaBH for the generation of As or Sn hydrides and for Hg CV generation. The volatile species were swept by Ar carrier gas for CVAAS detection of Hg at. nm or for ICP-AES determination of As and Sn. For the determination of Se the eluate was collected and analysed by ETAAS. Inorganic Hg and methylmercury were rapidly determined in fish by using a mixed solution of NaOH-NaCysteine to digest samples. Mercury was determined by CVAAS using a selective reduction step with SnC and SnC,-Cd solutions. Ethanol was satisfactory in preventing excessive foaming.Two optimum digestion procedures were found one using a dry block heater at °C for h and the second employing an overnight digestion at - "C. Differences between the two digestions were not significant at the % confidence level for the concentration range - ng g-' of Hg" and methylmercury in fish samples. Some reduction of the Hg signal due to matrix effects from different fish species was found. Oily fish shrimps and lobsters gave the greatest reduction in response and internal calibration by the addition of Hg standards was strongly recommended when exact quanti- tative determinations were required. The LOD was close to long g-'. The authors stated that the method could be applied to other matrixes including hair urine and blood with some modifications. Fish samples were analysed to deter- mine free and bound Ag Cd Cu and Zn in lobster digestive gland extracts.The samples were separated using gel- permeation columns packed with Sephadex G- or G- using ammonium acetate pH. as the mobile phase. Cadmium Cu and Zn were measured by FAAS and Ag was measured using ETAAS. If the samples were homogenized with. mmol - ' a-toluenesulfonyl fluoride TSF a protease inhibitor only Zn+ was found whereas Ag Cd and Cu were bound in both high and medium molecular weight fractions. In the absence of TSF Cd+ and Zn+ were released from their bound forms. The method was used to study the changes in bound and free metal ions during the processing of shellfish- based foods. Lin et al. reported the multi-element speciation of tea extracts using ICP-AES for Fe Mg Mn and Zn determi- nations and ETAAS for A determinations. All species were separated by HPLC. On-line detection was employed with ICP-AES and off-line detection with ETAAS.The results showed metals were differentiated as inorganic and organic species. Catechine complexes of Al Fe Mg Mn and Zn were employed as standards. The organic metal species in the tea extract gave almost the same retention time as the standards and it was therefore concluded that these elements are most likely to be in the form of flavanoid-type complexes. The speciation of trace metals in trace mineral supplements is of interest if the supplements are to have any benefits in terms of bioavailability. The total levels of nutritional toxic and other elements in dietary supplements were determined using ASV ICP-AES NAA FAAS and ETAAS. Elements were measured in dietary supplements. For most products A levels were explained by the presence of a soil component. Soil and excipient fractions were determined and the level of elements in soil and biological portions of matrixes were established. Potential element intakes from the supplements based on the label dosages and average dietary intakes from food were calculated. Some products provided levels of Cu Fe Mn Mo Pb and Zn which were in excess of levels generally accepted as safe by national and international organizations. Intakes of Ca Cr and Mg from some supplement products may augment average intake of foods to meet established nutritional requirements. Journal of Analytical Atomic Spectrometry April Vol. R . Developments in Methodology for Flame Atomic Absorption Spectrometry Cadmium was determined in biological materials by FAAS with FI on-line sorption and preconcentration. Rice was mixed with HN and the samples digested. After cooling HC was added the digest heated to near dryness and the residue washed and diluted with. mol -' HC.The sample was loaded into an FI system where it was merged with NaDDC and then passed into a PTFE knotted reactor. Cadmium complexed with NaDDC was absorbed onto the inner walls of the reactor and eluted on-line by IBMK.The retention efficiency was % at a sample loading rate of. ml min-'. The enhancement factor was and an LOD of. pg -' for Cd was obtained with a sampling frequency of h-'. Precision was.% RSD for pg -'. Thiourea and ascorbic acid-phenanthroline were used to overcome inter- ferences from Cu and Fe respectively. Flame AAS was used to determine traces of Zn in beverages after preconcentration in a liquid membrane. Soft drinks or beer were mixed with liquid paraffin emulsifier-sodium acetate-acetic acid-NaC.The resulting mixture was diluted with H and centrifuged. The inner phase was de-emulsified by applying a high-frequency high-voltage static electric spark V for lOmin diluted and analysed by FAAS. The LOD was. ng ml-' the average recovery.% and the RSD were.-.%. The results compared favourably with those obtained using an ashing technique. Two papers report the use of slotted tubes with FAAS for improving determinations using this technique. The first paper reported the determination of trace Cu in rice using conventional FAAS with a slotted quartz tube.The method was found to be rapid and low cost and the results obtained had an RSD of.% with recoveries of -%. The second paper used a single slotted silica tube to give an improvement in signal to noise ratio sensitivity and LOD for the determination of Pb in tap water. The analytical line of nm was chosen because improvements obtained in noise sensitivity and signal to noise ratio on this line were better than those for. nm. Using nm the LOD for Pb was.ngml-' with an RSD of.% for.ngml-l. The determination of Sr has been described in two papers. Trace Sr in natural mineral waters has been measured by FI-FAAS. An FI method for the preconcentration of Sr from natural mineral waters was developed based on ion exchange. For a sampling frequency of samples h-' a concentration factor of was achieved. As the preconcen- tration was carried out at an acidic pH interferences caused by foreign ions which were present in the sample were elimin- ated.The LOD for the method was ng ml-'. In the second paper stable Sr in milk and milk powder was determined by FAAS after ashing milk and milk-powder samples. The range of Sr concentrations determined in German milk and milk powder samples was - pg l-' in regions with the lowest concentrations and up to. mg -' in milk equivalent to. mg kg- ' in milk powder in areas contain- ing the highest concentrations. The lowest values were found for a baby food based on milk from a lowland area. The implications of the large variation in Sr concentrations in terms of radioecology were discussed in this paper. Also the publication discussed the significance of these values and the need to develop chemical separation methods for the determi- nation of Sr radionuclides with new selective ion exchangers. Lithium metaborate fusion was used in the analysis of wild rice for Ca K Mg and Si. Flame AAS was used to determine Ca K and Mg. Silicon was measured using Molybdenum Blue spectroscopy.Thirty-six samples were ashed overnight fused in h on the following day and analysed. R Journal of Analvtical Atomic Svectrometrv. Avril. Developments in Methodology for Electrothermal Atomic Absorption Spectrometry Two papers by Wei et al. described the determination of Si and Ge. For Si determination foods were digested with HNO in a microwave system with NHCl added to eliminate interferences by HN. Absorbance was measured by ETAAS using standard additions.The LOD was. pg ml-'. Germanium in foods was measured after the sample had been digested with HNO in a high pressure system. In order to increase the ashing temperature PdN was added to the sample solution. It also removed interferences caused by the sample matrix. The minimum detectable concen- tration was quoted as. mg kg-' with an RSD of less than %. Cernohorsky and Kotrly used tungsten furnace AAS to determine Be in drinking water. The use of a tungsten atomizer combined with the reductive reaction of H contrib- uted to the higher sensitivity obtained using the. nm line in comparison with the use of a graphite furnace. The addition of AlN as a chemical modifier eliminated interferences from Ca and Mg at concentration levels typical for natural waters.The authors comment that the method was suitable for rapid assays in the control of drinking water but it could also be applied successfully for the determination of Be in samples of contaminated water by using the method of stan- dard additions. The LOD for the method was. pg. Workers in Taiwan described a method for the determinution of Cd and Pb by direct injection ofmilk serum into the graphite tube of an electrothermal atomic absorption spectrometer. Raw milk samples were held at room temperature "C for h to allow the pH to decrease below. when casein and fat precipitated. The milk serum was then filtered and injected directly into a graphite furnace. Phosphoric acid was used as chemical modifier and the samples measured using standard additions. Oxygen prevented charcoal accumulation on the graphite tube during the ashing stage. Mean Cd and Pb values obtained for samples were for.ngml-'.-. and. ng ml- '.-. respectively.Tahvonen and Kumpulainen have reported a method to enable the LOD for Pb to be reduced by using the nm wavelength which is a more sensitive line than. nm and with Pd as a chemical modifier. Several RMs from the Agricultural Research Centre of Finland Central Laboratory ARC CL were used including potato powder animal muscle wheat flour and milk powder. Recommended values had been established using inter-laboratory comparison studies and other certification procedures. In addition commercial RMs such as NIST SRM non-fat milk powder SRM B bovine liver and some EC RMs were employed.The instru- ment was equipped with a Photron Pb Superlamp which give high lamp intensity. This combined with the most sensitive Pb wavelength resulted in better characteristic masses. In peak height type mode at. nm with the hollow cathode lamp the characteristic mass was usually. pg but at nm with the Superlamp the characteristic mass was - pg depending on the sample matrix. Low backgrounds were measured in all sample materials. It was not possible to use NaP as the chemical modifier with the nm line as PO- species cause spectral interferences at that wavelength. The accuracy of the method was satisfactory for the tested materials. Miller-Ihli describes an ETAAS method for the determination of Pb in sugars and syrups following wet ashing with HN-H. Magnesium nitrate was added as a chemi- cal modifier.The samples were analysed by using air-ashing platform atomization and quantification by peak area measure- ments with direct calibration against aqueous standards. The instrumental LOD was pg or. pg -l for a pl injection C'ol. corresponding to a method LOD of. ng of Pb per g of sugar. The characteristic mass was approximately pg. Two papers describe the measurement of edible oils andfats by ETAAS. Methods for the direct determination of Al Cr Cu Fe Ni and Pb in sunflower oil and olive oil were described. For Cu and Pb no matrix interferences were observed when samples were atomized directly off the tube wall. For all other elements a L'vov platform was required to eliminate interferences. Aluminium Cr Fe and Ni were quantified using a standard solution prepared in IBMK. For Cu and Pb the standard curve and the standard additions method gave similar results.The LODs ranged from. ppb for Cu to. ppb for Ni. Chromium Ni and Pb were not detected in any sample tested. The method was used to measure A and Fe after storage of oil in contact with various metals and alloys. Contamination with Fe was only detected in the olive oil that had been in contact with carbon steel with Fe concentrations increasing from when not in contact with carbon steel to ppb. Virgin olive oil showed lower stability after storage and contact with a carbon steel sheet than when stored in the absence of metal. The direct determination of particular elements in edible oils and fats was determined using an ultrasonic slurry sampler with ETAAS. The auto- mated ultrasonic slurry sampler yielded the same accuracy and somewhat better precision than the previously used laborious manual ETAAS method.The determination Cd Co Cu Ni and Pb in natural waters and the determination of Se in biological samples such as grain potato and cabbage was carried out after ultrasonication with Polyorgs YIIM sorbent. The biological samples were digested with HN,-H,O in an autoclave for h at -°C. The digest was adjusted to pH. treated with the sorbent and heated for min on a hot-plate or for - min in a microwave oven. The sorbent was then filtered off rinsed and water added. For waters - ml samples were ultrasonicated with mg of Polyorgs YIIM sorbent separated by centrifugation rinsed and left in ml of H. The resulting sorbent suspensions were introduced into the graphite furnace and analysed by ETAAS.The precision was improved by using ultrasonic mixing and an autosampler for the sample introduc- tion. The LODs pg -' were for Cd. for Co. for Cu and Ni. for Pb. and for Se. Developments in Methodology for Inductively Coupled Plasma Mass Spectrometry. The use of chromatography coupled to ICP-MS was described in two papers. Heitkemper et al. described the use of ion chromatography to determine residual bromate in baked foods. The determination of the flour improver potassium bromate was also described in a paper by Dennis et al. In this latter paper breadcrumbs were extracted with H and the filtered extract was applied to three anion exchange columns mounted in series and pre-conditioned with CH,OH-H-ammonium acetate. The KBrO was eluted with. mol -l ammonium acetate. A sub-sample ml was separated on a Dionex Ionpac SC column and a CG guard column with. mol -' ammonium acetate solution as the mobile phase. ICP-MS detection was carried out using Br.The ICP-MS method gave an RSD of % compared with an RSD of % for a GC method. The LODs were mg kg-' for HPLC-ICP-MS and mg kg-' for a GC method. Thompson described the determination of ultra- trace levels of Pb in infant formula by ID ICP-MS. After the addition of a known amount of ,Pb samples were digested in a microwave oven and the ratio Pb:Pb determined in the digest. Agreement with certified values for Pb in milk powder SRMS was good and ID using Pb yielded identical results for the SRMs. Typically RSD of <% were obtained with this method for Pb concentrations of about ppb.The recovery of ng of Pb from an aqueous standard taken through the microwave digestion was *%. Infant formula which contained. ppb Pb to which. ng of natural abundance Pb had been added to simulate a formula contain- ing. ppb Pb was analysed by ID. The result was L- % of the theoretical value. Therefore the authors concluded that differences of. ppb could be clearly distinguished and the LOD was estimated to be. ng g-' infant formula. The authors stated that the key to accuracy for this method was in minimizing contamination and accurately determining the concentration of Pb in the isotopically enriched standard. On-line sample dilution and internal standardization was carried out using an FI system coupled to ICP-MS. The method was used for the determination of Pb in wine and three calibration procedures were compared on-line isotope dilution on-line standard additions and external calibration. Overall the standard additions method was preferred with respect to accuracy precision and flexibility.The use of LA-ICP-MS for the multi-element analysis of biological materials was reported by Durrant and Ward. The use of a free-running ruby laser was compared with conventional pneumatic nebulization of the sample solu- tion following acidic digestion. Although inferior in both accuracy and precision LA-ICP-MS offered rapid semi- quantitative analyses with little or no sample preparation. Progress for Individual Elements. Arsenic A critical review of the determination of As in foods by atomic spectroscopy involving HG platform furnace and ICP has been produced by Cervera and Montoro.They state that HG has been largely displaced as a powerful tool by platform furnace with Zeeman background correction using the STPF concept for the control of interferences. Inductively coupled plasma with conventional pneumatic nebulization has been little used. An alternative is to employ HG-ICP with extraction of the As in an organic phase which permits an increase in sensitivity plus control over interferences. The method of sample digestion is dependent upon the matrix. One of the most shocking papers to be published in last review year was that by Chakraborti and colleagues. This paper deals with the contamination of ground water in districts of West Bengal in India with As. Using FI-HG-AAS biological samples as well as drinking water samples have been measured for As.The source of As is geological. Most of the water samples analysed contained a mixture of arsenite and arsenate and the organic forms of methylarsonic or dimethylar- sinic acid were not detected in any samples. The six districts affected have an area of km and hold a population of million people. Arsenic speciation in marine biological materials has been investigated using liquid chromatography with HG-ICP-AES. Not surprisingly the main As species found in these marine samples was arsenobetaine. A further paper from the same authors described the extraction methods for As species from samples of flounder sole mussel and cockles. Methanol-H,O + was considered to be the best extraction method and a procedure involving a C cartridge clean-up was proposed. The optimization of the extraction and clean- up procedures for determining arsenobetaine quantitatively in commercial seafood products was described.The authors used HPLC-ICP-AES. Real samples representative of fish molluscs and crustaceans were used. The Canadian National Research Council RM DORM- Dogfish muscle was used to establish the accuracy of the method. The analysis of DORM- provided an arsenobetaine value of.+. Journal of Analytical Atomic Spectrometry April Vol. I R mg g-' which agreed with results obtained from other authors using HPLC-ICP-MS. For the other species of seafood the percentage recovery for arsenobetaine was & % for cockles +% for sole and +% for prawns. The LOD of the method was. pg g-' of dry matter with an RSD of between and % depending on the fish species analysed. An LOD of. ng g-' in freeze-dried childrens' diets was quoted for samples prepared by furnace ashing with an ashing aid. Roxarsone -nitro-hydroxyphenylarsonic acid is a feed additive that is commonly used in the poultry industry.Three papers in this review report the determination of Roxarsone in various samples. Webster et al. reported the determi- nation of Roxarsone in feed using standard additions to diagnose matrix effects in AAS analyses. The authors state that the additive is routinely assayed in industry using AOAC official methods. and. The latter is an AAS method which was judged by the authors to be quite advanta- geous because it is both accurate and efficient. However occasionally the analysis of feeds by this method yields ques- tionable results.The authors recommend the application of standard additions to detect this problem in future analyses. In a second paper As residues were detected in egg components from laying hens that were fed either control or diets treated with the organic arsenicals arsanilic acid and Roxarsone. Arsenic residues in both yolk and albumen increased in a dose-dependent manner although the amount of As was much higher in the yolk % of total. Arsenic concentrations increased within week of treatment and the highest amounts were obtained between the second and fourth week for yolk samples. Hens treated with ppm of As from arsanilic acid produced eggs with As residues exceeding the ppb Food and Drug Administration whole egg tolerance level. In a very similar paper by the same authors the egg sample was subjected to HN digestion and the As concentration was determined by ETAAS. Again it was stated that As residues in both yolk and albumen increased in a dose- dependent manner although the amount of As was much higher in yolk. Boron Boron analysis in foodstuffs can be difficult.The determination of B by diflerent methods was compared following microwave digestion of some biological materials. Analysis was performed by photometry with azomethine-H fluorimetry with carminic acid ICP-AES and ICP-MS. For all of these methods matrix interferences interferences caused by Fe and LODs were investigated. In particular the materials investigated were wheat milk meat and plant materials. The recoveries from and precision of all the methods were studied using four NIST SRMs. Good recoveries were found for all of the methods except the fluorimetric technique.The best precision was obtained for the two ICP methods and the azomethine-H method gave good results when material of high B content was analysed. The method involving carminic acid produced no reliable results. Chromium An ETAAS method has been developed for the determination of total and hexavalent Cr in animal feeds. Total Cr was measured after digestion in HN-HCl-HF. A CrV' standard was prepared by dissolving KCr in. mol -l NaOH solution. A mixture of Pd + Mg was used as chemical modifier. Validation of the proposed method was carried out by using both standard additions and analysis of NJST SRM total diet. The LODs were. and. pg -l for total and hexavalent Cr respectively. Similarly the RSDs were. and % for total and hexavalent Cr.The proposed method was considered satisfactory for routine analyses. In a total of samples that were analysed the mean levels were. pg g-' for total Cr and ng g-' for Cr"'. In both in- stances large variations in concentration were found and this was stated by the authors to show the diverse contamination of raw materials used in the preparation of animal feeds. The effect of season and species of plant on the ash and Cr content of honey was studied. Four types of honey were studied sunflower acacia floral and wild floral. The botanical origin of the honey was determined by microscopic analysis of pollen as well as the organoleptic properties. Chromium was measured by FAAS. There were statistically significant influences of season on the ash content as well as the interaction of species and season on the Cr content. Chromium was determined in cereals by ETAAS following dry decomposition and dissolution of the sample. Chromium was extracted with diphenylcarbazide in -methylpropan-.The RSDs for Cr in cereals in the concen- tration range -. pg g-' was from.-.' with an LOD of. pg g-'. Mercury A gas cell designed to determine small amounts of Hg when used with single-slit air-CH or CH-N,O burners was described. The cell consisted of a molybdenum glass tube with gas outlets attached at a distance of mm from the optical windows of the cell. Windows of mm thick optical quartz were attached to the ends of the tube perpendicular to optical axis of the cell. The cell was fastened to the burner by two spring-loaded clips with pieces of fluoroplastic pipe mounted on them screwed to the burner.The cell was installed with two sections of glass pipe placed under it. A section of Nichrome wire was wound on to the cell tube to supply current to combat condensation. The cell was set up and adjusted in min. The LOD was long of Hg and the instrument could be used to detect Hg in vegetable animal and mineral oils. A self-made T-shaped quartz tube was described for the HG-AAS determination of Hg in water. Water was reacted with KBH in the hydride generator and the generated hydride was transferred by Ar carrier gas to the T-shape quartz tube for atomization. The measurement was performed at. nm. The LOD was. ng ml-' and the RSD was.%. The method was applied to drinking and household waters as well as industrial waste waters. Two mineralization procedures for biological materials prior to the determination of total Hg by CVAAS were described.The mineralization procedures were performed in Parr digestion bombs heated by either convection or micro- wave irradiation. Some NIST RMs were used to verify the method including NIST RM Albacore Tuna. No significant differences p >. were observed in Hg concentrations in samples decomposed by convection and microwave heating. For mg of biological material mineralized and diluted to produce ml of solution the LOD was. ng g-' of Hg in the original solid sample. An RSD of.% was found for both the within- and between-run precisions. However the convec- ition heated digestion required considerable time approxi- mately h including two h cooling intervals but the method was recommended for processing a large number of samples. 'The microwave mineralization was found to be much faster laking approximately s.The authors concluded that the destruction of the organic matter was achieved efficiently by using either of the mineralization procedures. An LOD of. ng g-' wet mass was reported for a national study of Hg contamination of fish. The improved ,OD was achieved by reducing the sample size from to. g and screening reagents for low Hg content. Samples were digested in a mixture of HN-HS followed by the R Journal of Analytical Atomic Spectrometry April Vol. addition of KMnO and further digestion. Potassium sulfate was added and the solution boiled cooled and treated with NaC-hydroxylamine sulfate solution and either SnC or SnSO,. Mercury was analysed by CVAAS with deuterium background correction. Analysis of Hg by CVAAS was used to determine the average weekly intake of Hg in the diet in Italy.The data were required in order to verify whether the intakes corresponded to the provisional tolerable weekly intake PTWI established by the FAO-WHO i.e.,. mg per week. The weekly intake values ranged between. and. pg for two types of diet. Iodine Schramel and Haase reported the determination of I in biological materials by ICP-MS. Liquid samples were ana- lysed directly after dilution; milk powder plants and tissues were dissolved using an ashing procedure with the residue being taken up in NaOH and the resulting solution being analysed by ICP-MS. The LOD was in the order of. pg I-' and the method was tested using CRMs certified for I content. Selenium Several papers reported methods for the determination of total Se in various food samples. A Korean paper reported a method to improve the sensitivity of current assay techniques for Se and dried yeast preparations.The sample was digested with HCl-HN,-HClO having been pre-treated to remove ether-soluble substances. The quantitative range was given as.-. pg ml-'. Selenium is present in animal feed sup- plements mineral mixes premixes and as an injectable solution as selenite Se" or selenate SeV'. Anderson et al. described a simple method for the determination of Se in feedstuffs. High concentrations of other common minerals present in these types of supplements were also tolerated by the method. The samples were initially digested by heating with HNO and then boiled with H,SO,-HClO to convert all Se species to Se".The SeV' was reduced to SeIV with HC at °C. In turn Se" was reduced by acidic NaBH to HSe which was measured by HG-ICP-AES at. nm. The LOD for this method was. mg -l. Recoveries of Se were -%. The method was described as being suitable for the determination of Se in samples in the range.- pg g-' of sample. The Se content of infant formulae was measured after microwave digestion. Samples. g were digested with HN,-H in a medium-pressure microwave digester. The digestate was mixed with CuNO,-MgNO and diluted to ml with H. This digestate was measured by ETAAS with drying for s at "C charring for s and s respectively at and "C atomization for s at "C and cleaning for s at "C. Detection was carried out at nm. The LOD was.nm g-' with an RSD of.%.The accuracy of the method was tested by comparison of results for an RM. Good agreement was obtained. Electrothermal AAS using Zeeman background correction and Pd as chemical modifier was used to measure Se in human milk in Niger. Within-run precision was.% and the between-run precision.%. The precision and recovery of standard additions YO were sufficient to allow the routine determination of selenium in breast milk. The values for Se in breast milk were compared with the Se level in the mother's serum parity age of the mother and age of the previous child. No significant correlation was found between the breast milk Se and these parameters. Minerals and trace elements were measured in Chinese selenium tea and its infusions by ICP-AES ETAAS and instrumental NAA. The China's Enschi district in Hubei province is one of two seleniferous regions producing both selenium black tea and selenium green tea.Three samples of green tea with different Se contents and one non-selenium tea were analysed. The following elements were determined by ICP-AES Al Ba Ca Co Cr Cu Fe K Mg Mn Mo Na Ni P S and Zn. The Se content in the tea samples and infusions were measured by ETAAS. The accuracy of Se determinations was tested by measuring untreated tea samples with instrumental NAA. The Se content was -. pg g- '. Up to % of a total Se was found in the first infusion made from the tea. The results for untreated tea samples by ETAAS were consistent with those obtained by NAA. Selenium was deter- mined in tea garlic bulbs and rice by FAAS with a slotted quartz tube. The slotted quartz tube was used to increase the sensitivity of conventional FAAS. It was used in conjunction with an air-CH flame.The recovery of Se was -% for rice -% for garlic and -% for tea. The respective RSD were.,. and.%. Garlic as well as Ginseng radex and Ganoderma hicidum was also measured for Se in a paper by Cha et al. The samples were measured by using HG-AAS. The effects of several acids and NaBH concentration and their flow rates on the determination of Se by HG were investigated. Sample decomposition using various mineral acids such as HNO, HClO and HS was also investigated in a closed system. The data for garlic Ganoderma hicidum and Ginseng radex indicated Se levels of and ppb respectively. Hydride generation ICP-MS was used to determine Se in wheat based on the method of ID.The method involved wet digestion with HNO in a high pressure asher with subsequent on-line generation of the hydride in an FI system without a pre-reduction. The calibration was based on ID with Se as the spike relative to Se as the reference isotope. The Se-Se ratios were measured. The accuracy and precision of the procedure was established using BCR SRM wheat flour. Good agreement with the certified value was obtained. The need to correct for mass discrimination was discussed and neglecting instrumental mass discrimination gave a bias of about %. Comparing some of the results with those obtained using instrumental NAA showed satisfactory agreement. Selenium was determined in wheat flour samples by ETAAS using automated ultrasonic slurry sampling. The method used a Pd-Mg chemical modifier and slurries were prepared by adding ml of an acidic diluent containingTriton-X. The proposed method gave good accuracy and precision as judged by the data obtained for NIST SRM A wheat flour. Repeatability of the method using a % m v slurry was.% with an LOD of. pg g-'. In a paper from China standardless analysis of Se was described for powdered samples of wheat flour pork liver and wild cabbage. The term standardless was slightly confusing as the technique appeared to involve standard additions with additions being made directly to the slurry prior to application onto an automatic sampler for ETAAS determination of Se. The method was suitable for the analysis of samples containing more than. pg g-' of selenium. The RSD was %. Two papers describe the determination of Se in fish. Four microwave digestion methods for fish tissue were compared by Lan et al.The methods which employed HN,-H, HN-KS-H and HN-HP-H were judged to be unreliable. However by using HN,-KS-H an adequate digestion was obtained for fish tissues and the Se was retained in a state amenable to determination by HG-AAS. The recoveries from spiked samples using this method were -%. The LOD was. pg -l on a dry mass basis for a mg sample. The contents of Se in local fish species were.-. pg g-' and the RSD was less than % for the method. In the second paper Se was determined in fresh fish from South Eastern Spain for calculation of daily dietary intake. The fresh Journal of Analytical Atomic Spectrometry April Vol. R fish samples were lyophilized and then mineralized with HN,-HC prior to Se determination by HG-AAS.The LOD was. ng. Relative standard deviations ranged from to.%. The average daily consumption of fresh fish in this region was calculated and the daily dietary intake of Se supplied by this source was. pg d-' for an adult. The precision of isotope ratio measurements for Se using I D with a nitrogen microwave induced plasma was reported. The precision for the Se:Se ratio in a ng ml-' standard solution was.% under practical ana- lytical conditions and could be lowered by increasing the integration time. The spectroscopic interference at m z = arising from SO+ was observed but was not such as to cause a serious problem at the S level normally found in biological materials. Isotopic ratios in digested clinical specimens agreed well with those in the standard solutions indicating no other spectroscopic interferences on Se isotopes in real samples.The method was successfully applied to the analysis of Se in biological RMs. Two papers describe the determination of SeV and Se'" by on-line speciation techniques. Pitts et al. described an FI approach using on-line microwave reduction followed by HG-quartz furnace-AAS. The RM NIST C trace elements in water was used to test the method. The sample was mixed with HC and pumped through a heating coil inside a microwave unit operating at % of maximum power. The heated solution was passed through to a reaction coil and subsequently mixed with NaBH,-NaOH after passing through a gas-liquid separator. The H,Se was detected by AAS at nm. A linear calibration graph was obtained for up to pg -l of sodium selenate.The results for the RM agreed well with the certified values. An automated system was then developed for Se speciation in which the sample was first analysed for Se" then heated to reduce SeV and analysed for total Se. The sample throughput was h-'. The LODs and precision were unaffected by the on-line reduction step but recoveries were improved. On-line speciation of selenium v~ seleniumv and trimethylselenium was described by Cobo- Fernandez et al. Tapwater samples were injected through a six-port low-pressure sample injection valve into a buffered PO,- solution thence to an ion exchange column. The eluate was mixed with KS solution and then heated in a microwave oven at W in a reaction coil. The sample was cooled in an ice-bath and Se" species reacted with.% NaBH,.The Se hydride was carried by Ar to a gas-liquid separator and then to the AAS instrument. Recoveries were nearly quantitative absolute LODs were. ng for trimethylse- lenium and. and. ng for seleniumv and seleniumvI respectively. Relative standard deviations were less than %. Uden et al. described the speciation of organoselenium and other organometallic compounds in foods and the aqueous environment using GC with AE detection C C. Gas chromatography with AE detection was able to provide high sensitivity and characterization of compounds by means of element specific determination. Uden and col- leagues have published a paper on the identification of natural abundance organoselenium volatiles from garlic elephant garlic onion and Chinese chive using headspace GC with AE detection.The plant materials studies are all mem- bers of the Allium family which tend to contain more Se than most other vegetables. The current interest in Se is due partially to its role as an essential element and partially to the fact that in excess it can be toxic. In addition Se may be beneficial in preventing cancer Atomic plasma spectral emission provided a powerful element-specific detector for GC. The AE detector response flags compounds in the GC effluent that contained specific elements. Uden et al. used the Se emission line at. nm to determine organoselenium species while concur- rently monitoring C and S by lines at. and. nm respectively. By using empirical formulae calculations utilizing compound-independent calibration were employed for quali- tative identification of the Se-containing peaks.These assign- ments were confirmed by headspace GC-MS. The above techniques were used to analyse the headspace above the homogenized garlic elephant garlic onion and Chinese chive samples. As the headspace GC-MS procedure was not suffic- iently sensitive and selective to directly detect natural levels of Allium Se compounds garlic grown in an Se fertilizer medium Le. Se-enriched garlic or garlic homogenates augmented by addition of Se amino acids were used. A number of volatile Se compounds were detected from all four samples including dimethyl selenide methanesulfenoselenoic acid methyl ester dimethyl diselenide bismethylthio selenide ally methyl selen- ide prop-enesulfenoselenoic acid methyl ester and prop- enesulfenoselenoic acid methyl ester. In addition allylthiome- thylthio selenide and bisallythio selenide were found in garlic and elephant garlic.The effect of increasing Se levels in the volatiles to facilitate GC-MS identification also elucidated possible sources of Se. For example addition of selenocystine to onion or garlic homogenates enhanced the formation of bismethythio selenide and in the case of garlic allylthiome- thylthioselenide and bisallythio selenide. Similarly the addition of selenomethionine to onion and garlic homogenates enhanced the formation of methanesulfenoselenoic acid methyl ester in both cases. The detection of eight compounds of Se in Allium headspace volatiles and the strong garlic odour of the synthetic compounds indicated to the authors that it was probable that many of those compounds would be exhaled in trace amounts in 'garlic breath' and that these should be detectable using the GC-AE detection technique.The authors have in fact pursued this and in a paper on Allium chemistry entitled 'Identification of Natural Abundance Organic Selenium Compounds in Human Breath after Ingestion of Garlic using GC-AED' have described the method for determining and characterizing for the first time in 'garlic breath' the presence of significant amounts of organoselenium and mixed organoselenium-sulfur compounds J. Agric. Food. Chem.,. In a further paper by this group the headspace sampler that had been interfaced with GC and used to determine trace levels of volatile organoselen- ium in garlic flavorants was described. The volatiles from crushed garlic were detected by AE and MS. The determination of free selenomethionine by HPLC coupled to thermochemical HG-AAS has been described.The selenoamino acid in alkaline solution was first derivatized with l-fluoro-,-dinitrobenzene FDNB Sanger's reagent after removal of excess of the reagent by partition with diethyl ether. The N-dinitrophenyl DNP derivatized selenomethionine was protonated by acidification and extracted with diethyl ether. The DNP-selenomethionine was determined selectively by HPLC-themochemical HG-AAS. Ascorbic acid which was present in large amounts in some nutritional supplements was revealed to be the major interference during the DNP derivatiz- ation step. This interference was removed by use of cation exchange treatment Dowex W-X column of the crude extract prior to the derivatization. The recoveries of selenome- thionine from stock solutions and nutritional supplements were virtually quantitative +.%. In the presence of a -fold excess of other amino acids this recovery decreased +.% but remained in an acceptable range to allow the accurate determination of selenomethionine in a protein hydrolysate. In a conference presentation C the separation of selenomethionine from SeV' Se" and selenocys- tine standards was described using HPLC ion exchange coupled to ICP-MS.The LOD was stated to be ppb. The accuracy of isotope ratio measurements associated with the separated species was within -% of the expected ratio. We look forward to seeing this work published. R Journal of Analytical Atomic Spectrometry April Vol. . Tin. The extraction and determination of butyltin compounds in shellfish by HG-GC-quartz furnace AAS was reported.The method involved the conversion of butyltin compounds extracted from shellfish into volatile hydrides by NaBH, followed by cryogenic trapping and selective volatiliz- ation using on-line quartz furnace AAS detection. The digestion method chosen utilized. mol -' HCI in.% CH,OH under sonication for h. The recoveries of mono- di- and tributyltin compounds from spiked mussel and oyster samples ranged from to % with low degradation of butyltins. The LODs were in the - ng g-' wet mass range. Giordano et al. describe the use of Zeeman ETAAS to measure tricyclohexyltin hydroxide cyhexatin. This com- pound is widely used as an acaricide on both fruit and vegetables. The methods used to determine this compound tend to be lengthy and are often seriously affected by inter- ferences.The study was undertaken to assess the use of ETAAS for measuring the Sn component of this compound. Preliminary experiments showed that both pyrolitic tubes with a L'vov platform and titanium-coated tubes performed well. The validity of the method was verified by the sensitivity detection power and reproducibility of figures given by each type of tube used. An extraction method for butyltin cyclohexyltin octyltin and phenyltin compounds in wines was developed. The compounds were detected in blended wines and were extracted using.% tropolone in % diethyl ether-pentane. Recoveries ranged from to %. Methyl derivatives made by the Grignard reaction were quantified using GC-AAS. Of the samples tested contained at least one of the analytes. Mono- and dioctyltin were found in one sample only at levels of. and. ng ml-' respectively. Dibutyltin levels ranged from less than. to. ng ml-'. Both monobutyl- and tributyltin were found less frequently and at lower levels than butyltin. No other organotin compounds were detected by either GC-AAS or GC-MS. Single and Multi-element Analysis of Foods An impressive number of Polish papers have been published by Falandysz et al. in which a range of elements were analysed primarily using FAAS.The Mn content of food available in Northern Poland has been described in one of these papers. The method used incorporated dry ashing of samples followed by FAAS measurement. A range of Mn concentrations was obtained for a variety of foods including vegetables both root and leaf as well as wild strawberries parsley leaves sunflower seeds and black tea. In addition cereal and cereal products in particular bread flakes and groats as well as some imported products such as processed pineapple rice and spices were analysed.These foodstuffs were rich in Mn as were meat and fish products. Average Mn concentrations for meat prod- ucts ranged from. to. mg kg-' in muscle meat,.-. mg kg-' in liver meat and.- mg kg-I in the kidneys of slaughtered and game animals. The level in fish from the Baltic was.-. mg kg-'. In contrast most vegetable varieties contained < mg kg-' of Mn while a few were as high as mg kg-l. The highest value of all was found in black tea which had an average value of ml kg-'. In total the Mn content was measured in over samples of food which had been available in Northern Poland between and.The same group report data for Cu Fe Mn and Zn in fruits cultivated in the provinces of Gdansk and Elblag in apples from the same district but related to seasonal content in nuts almonds raisins and cocoa in edible tubers roots root stocks fruits and seeds of vegetables and in leafy vegetables. All of the measurements were made by FAAS with the highest levels of Cu Mn and Zn being found in nuts seeds and raisins. The lowest levels were found in apples and fruit products. A further paper described the analysis of the same four metals in tea infusions of different strengths. The teas were imported from China India Indonesia and Vietnam and were infused with boiling tap or distilled water. The metal contents of both leaves and infusions were determined by FAAS.The amount of metal leached varied with the metal the tea and the amount of tea and water used to make the infusion. Falandysz et al. also report in two papers the metal content of wild growing mushrooms gathered in Northern Poland. The contents of Ag Cd Cu Fe Mn Pb and Zn were determined in species. The Ag content was determined in a total of species. The samples were dried at "C for h weighed and ashed at "C. The residue was wetted with HNO, re-ashed and the residue dissolved in HNO prior to measurement by FAAS using an air-C,H flame. The concentration ranges for each of the elements were as follows mg kg-' dry mass Ag.-. Cd.- Cu.- Fe.- Mn.- Pb.- Zn.-. The Hg content of these mushrooms was also determined. The samples were treated with concentrated HNO prior to measurement of CVAAS; the average concentrations of Hg depended on the species of mushroom. For Agaricus campestiris the level of Hg was.-. mg kg-'. For A.agustus the range was.-. mg kg-' and for an unidentified specimen of Agaricus species the range was. to mg kg-'.These values were compared with cultivated A. bisporus specimens which had a range of. to. mg kg-'. A second group of Polish workers describe the methods for measuring the A content of food products by ETAAS and the determination of As Cu Pb Sn and Zn in bottled fruit pulp and jams by FAAS. The levels of As Cd Pd Cu Sn and Zn in preserved vegetable and vegetable meat products produced in Poland were also measured.For As an Ar-H flame was used for HG-FAAS determination. The remaining elements were determined in acid digests except for Pb which was measured after complexation with DDC and extraction to IBMK. Addition of % isopentane was used to improve the analysis of the fruit composite and jam samples. A paper by Kozak et al. also investigated the trace metal content of fruits growing in the region of Lublin in Poland.The levels of Cd Cu Fe Mn Ni and Pb were measured in samples of fruit. In a paper from the Czech Republic C various decomposition methods including the use of open PTFE- vessels high pressure digestion in a microwave system and dry ashing using a superoxidation gaseous mixture of ,-,-NO, have been tested and used to determine Cd Cu Mn Hg Pb and Zn. The open PTFE vessels in combination with FAAS were found to be sufficient for the determination of Cu Mn and Zn. The use of a microwave system with CVAAS was discovered to be the best for Hg measurements whilst low temperature ashing was used for the determination of Cd by FAAS and Pb by ETAAS.These methods were used to monitor the above elements in edible fungi and blueberries from a network of sampling points across an area of the Czech Republic. Two cases of anomalous levels were observed; firstly Cd in one of the edible fungi had a range of.-. mg kg-' dry mass and secondly Mn in blueberry leaves had a range of - mg kg-'. Lead was measured in cereals by ETAAS following mineralization and dissolution of the samples and extraction with NaDDC in CC,. By using this method it was possible to determine lead in cereals down to. pg g-'. The RSD for the concentration range.-. pg kg-' was from. to.%. The same group determined Ag in cereals. In this case Ag was extracted into IMBK after complexation with diphenylthiocarbamate.The precision of the procedure was.-% RSD Journal of Analytical Atomic Spectrometry April VoZ. R for up to. mg g-' of silver in the cereal. The LOD for Ag was. mg kg- '. The paper reported the results for different cereal samples from the Skopje region of Macedonia in Yugoslavia. Another paper reported the levels of Ca Cu Fe K Mg Mn Na and Zn in similar samples from the same region. Heavy metals were also determined in fruiting bodies of wild mushrooms from the Czech Republic. Mercury was determined using CVAAS. The remaining elements Cd Co Cr Cu Fe Mn Ni Pb and Zn were measured using FAAS. Cadmium values ranged from. to. mg kg-' dry matter. The statutory safe limit for Pb was exceeded by several samples from an industrial area.The largest contents of all of the metals were found in the gills of the mushrooms. The consequences of consuming wild mush- rooms containing high levels of Cd and Hg were discussed. A number of papers reporting the elemental content of Chinese foods have been published. The determination of trace elements in various alcoholic drinks from the Shanxi district of China has been reported. The levels of Co Cr Cu Fe Mn Mo Ni Sr and Zn were determined simultaneously by ICP-AES. A method for the rapid determination of Cu in egg white and yolk in which samples were digested in PTFE closed vessels in a microwave oven was described. The Cu was determined by ETAAS and the method was described as safe rapid and simple with high accuracy.The determination of Ca Cu Fe K Mg Mn Na and Zn as well as other trace elements was reported by Wang et al. Measurements were made for Cu Fe and Mn by air-CH FAAS. Calcium was similarly determined after mixing with.% La and Mg Na K and Zn were measured after further dilution. The foods measured were bean milk crystals and instant milk powder. Arsenic Cd Cu and Pb were determined in food additives by ETAAS. Ninety-one foods were analysed for Cu Fe Mg Mn and Zn. Manganese was found to be higher in beans and black rice than in any other food. Copper Fe and Zn predominated in meat and offal samples although Fe was also high in wheat flour dried bean bean curd and spinach. The four essential trace elements were found to be low in kinds of freshwater fish. For Mg grains were found to have generally higher levels than any other food. Zhang et al. measured the content of Ni Se'" and Sr in the different parts of ginseng as well as looking at the seasonal variations and the trace element content of the growing fields.The results were used to provide data for improving the planting selling and comprehensive utilization of Jilin ginseng. Seven elements were determined in edible fungi using a closed digestion-FAAS method. Flame AAS was used to measure Fe and Mn in soya bean and tea. Calibration graphs for Fe and Mn were linear up to and pg ml-' respectively. Recoveries were -% with an RSD of.-.%. Flame AAS was also used for the determination of Cu Sn and Zn in canned foods. For the determination of Sn the use of K as an 'anti-ionizer'. mg ml-l was reported and the absorption enhancement of P- relative to Sn was decreased by reducing the fuel-to- oxidant ratio of the flame.The recoveries were % for Cu % for Sn and % for Zn. The mineral content of milk samples has been reported in various papers. Moreno et al. reported the levels of elements in Spanish sterilized milk. The contribution of this foodstuff to the elemental content of the Spanish diet was estimated. On a daily basis the milk contributed the following mg of Ca; pg of Cu; pg of Fe; mg of K; mg of Mg; pg of Mn; mg of Na and. pg of Zn. The Cu Fe Mn and Zn content in human colostrum and transitory milk from French women was reported by Arnaud and Favier. Zinc was analysed by FAAS and the other elements by ETAAS. The Cu concentrations remained constant whilst the Fe Mn and Zn levels declined at various times post partum.The Cu concentrations were also related to the maternal body mass index. Raw cow ewe and goat milk was analysed by Moreno et al. in a paper investigating the concentration and seasonal variation of Ca K Mg and Na. Samples were measured by FAAS. Aluminium levels in soya-based infant formula were measured by ICP-AES. The A content of the soya-based samples ranged from. to. mg -'. This compared to the aluminium levels in reconstituted cow milk based formulas of. to.mg -'. Multiple regression analysis has been reported for the evaluation of primary cation data for raw milk and multivariate factor analysis was used to study the effects of pasteurization sterilization and drying of milk on mineral conent,. The two papers studied the trace metal content of cow and buffalo milk.Three papers report the analysis of cheese. The effect of processing on the concentration of Pb in Manchego- type cheese and also the contents of Cay Mg Mn Na and K in the same type of cheese during ripening were reported. Slight increases in the Pb content were due mainly to the retention of Pb by the curd and also to possible contamination which occurred during processing. Levels of As Cu Cd Fe Mn Ni Sn Pb and Zn were reported for brined canned cheese. Although metals levels were generally comparable with the literature data the work showed that white brined cheese picked up metals from tin containers and from the naturally contaminated salt. Cheese in glass jars showed lower levels of metals. Therefore the authors rec- ommended the use of purified salt for the preparation of brined cheeses and that glass jars should be used for white cheese preservation. Papers from different parts of the world have investigated the contents of various elements in tea. Levels of A and Mn in tea leaves and tea infusions was investigated using ETAAS,. In this Japanese paper the influence of infusion conditions on the elution of these two elements and the daily intake of them was estimated. From a tea infusion of ml the estimated intake of A was.-. mg d-' and for Mn.-. mg d-'.This represented -% of A intake and -% of Mn intake from foods. The effect of the infusion procedure on leaching yield of Cu Fe and Mn from tea leaves was measured by Flanadysz. Samples of black tea imported into Poland from China India Indonesia and Vietnam as well as those from England and Holland were infused using five different infusion procedures and the levels measured by FAAS. Significant variations in leaching yield were observed for the analytes depending on the infusion procedure used. Both ICP-AES and FAAS were used to investigate the content of seven essential trace elements in tea used in Pakistan. Four papers reported the determination of Al in beer. Aluminium was determined in lemonade and beer stored in bottles or cans. In beer stored in aluminium barrels the levels of A varied from. to. mg -' which was - times higher than that found in beers stored in bottles. A collaborative study was made of a method for the determi- nation of A in beers by ETAAS. Five pairs of beers with a range of A concentration of - mg -' were analysed by laboratories.The repeatability was - mg -' and the reproducibility was - mg -'. A second collaborative study in which the method was slightly modified failed to give better results.This paper serves to illustrate the difficulties of A analyses. The authors state that in view of the high values for reproducibility the method was not adopted as an approved analytical method in Spain. Aluminium was determined in de-gassed samples of beers following three-fold dilution with H and measurement by ETAAS at. nm. The optimum ashing temperature was found to be °C and there was no need for the addition of a chemical R Journal of Analytical Atomic Spectrometry April Vol. modifier. For.ngml-' A the RSD was.% with an average recovery of %. The results were comparable for this direct measurement technique to those obtained after digestion.The use of ETAAS for the determination of Zn in wort and beer has been reported. A previously reported method was evaluated and results of collaborative tests showed that the repeatability coefficients ranged from. to.% and were considered to be acceptable. However the reproducibility coefficients ranged from. to.% and were considered unacceptable. A quick easy method was reported for the determination of Pb in table wines using ETAAS with Zeeman background correction and a L'vov pyrolytic graphite platform. Ammonium dihydrogenphosphate was used as a chemical modifier. The wines were diluted by a factor of with % HNO and analysed directly. The absorbances were compared with those of a standard calibration curve prepared with a % HNO,. Analytical results obtained by comparison of the data from the standard curve agreed with those obtained by the method of standard additions. In total four white four red and two rosk wines were studied. Wines fortified with lOOngml-' had an average recovery of %.The average short term RSD was.% and the long-term RSD was.%. The estimated LOD and LOQs were and ngml-' respectively. Manganese was determined in European wines. Thirty-five different red white and rosC wines pro- duced in several European countries were measured by ETAAS. A mean concentration of.+. mg -' was obtained with a range of.-. mg I-'. No statistical difference was observed between all red and white wines. Red Beaujolais wines had a higher Mn content P<O.Ol. Factors affecting the Mn content of wine were discussed. A second paper on Pb evaluated the actual concentration of this element in Italian wines.The paper reported the determination of Pb in wines with representative samples from the entire Italian production taking into consideration different geographical areas and vinification processes. Three hundred and twenty samples were measured and the average levels of Pb <. mg -' were significantly lower than the Italian legal limit. mg -'. The paper considers the possibility of re-evaluating the legislative limit. A specific method for the determination of Zn in wines by FAAS was published.The paper reports that matrix effects were avoided by using the standard additions method. Results were obtained within - s for direct atomiz- ation of the wines and the coefficient of the variation was <%. A second paper from Italy discussed Cu Pb and Zn in wines produced in the Arezzo region.The three elements were measured in local wines of the area during and. Copper was generally below legal tolerance although it exceeded mg -' in a few samples Pb rarely exceeded. mg -' and Zn exceeded mg -'. The simultaneous multi-element analysis of 'so-called health foods' by ICP-AES was reported by Japanese workers. The commercial health foods consisted of samples of mushrooms tea leaves shellfish seaweed Chinese natural drugs vegetable and animal oils. The samples were digested with HNO in a Teflon vessel digestion bomb prior to measurement. The As B Cd and K concentrations were high in seaweed products Al Cu and Zn levels were high in oyster extracts and Ba Mg and Mn were high in products containing Aloe arborescens. Generally vegetable oil egg yolk oil and horse oil-containing products were low in these analytes. In some food products additives such as iron@ sodium citrate and powdered bovine bone affected the elemental concentrations.The content of monosodium glutamate in processed foods and the influence on analytical methods for sodium determi- nation were discussed by Fujisawa and Nadamoto. The NaCl and monosodium glutamate contents in process foods were measured and the ratio of Na originating from the monosodium glutamate to total Na was estimated. In out of foods analysed the ratio was greater than %. In particular pickled vegetables soup powdered fish and other foods eaten with cooked rice fish paste and Chinese foods showed high ratios. The methods used to determine Na content included AAS determination using an electrode and the Mohr method; all showed a high correlation with monosodium glutamate content. Cadmium was measured by ETAAS for determining residual levels in this element various food samples. Cereal vegetables fruit vegetable oils milk and poppy seeds were subjected to wet ashing and extraction with organic solvents prior to measurement by ETAAS. Rinkis et al. described a method for eliminating background interferences caused by the macro-elements Ca K Mg Na etc. For solutions of plant or animal ash the background interfering elements are separated from the analyte by the use of dithizone in CC.The A content of some selected Indian foods was measured by FAAS. The Indian foods were in general found to have lower A contents compared with published A levels for foods. Cadmium Hg and Pb were measured in Slovak total diet samples using ETAAS for Cd and Pb and CVAAS for Hg. On the basis of the data the authors concluded that the levels of the toxic elements in the total diet were in good agreement with data from other authors and did not exceed the maximum permissible concentration pro- posed for adults by the FAO-WHO.The accuracy of their results was verified by using CRMs such a Bowen's Kale NIST CRMs and IAEA mixed human diet H-. Yasui et al. studied the eflects of major elements on emission during ICP-AES determination of inorganic elements in foods. Model solutions with compositions similar to that of highly polished rice soya bean soya sauce and edible seaweed were used. When the concentration of salt in the sample solution was below. YO emission of Cu Fe Mn Sr and Zn were not affected by the presence of major elements such as Ca K Mg Na and P. When the ash concentration the sum of the aforementioned interfering elements was above.% it was necessary to use standard solutions of the minor elements containing the major elements. A rapid and precise procedure was described for the determination of lead in food and feed products by ETAAS. Samples were min- eralized in a microwave acid digestion bomb with HNO and V. Lead concentrations were determined in the digested samples and the LOD was. ng ml-'.The method was tested on food and feed crops from Mediterranean zones in Spain and found to be suitable for this type of product. Lead concentrations in these samples ranged from <LOD to. pg g-' fresh mass. Levels of Ag Fe Pb and Zn were determined in oranges and avocados from two gold-rich towns and compared with levels in an adjacent gold-deficient town.The Ag and Fe levels in fruits were highest in one of the gold-rich areas and least high in the control area. Similar amounts of Zn were found in one of the gold-rich towns and the control area but they were very much higher > mg kg-' in fruit from a farm in the other gold-rich area. Lead did not show any geographical variation. Levels of As and Pb in cherries harvested in the years - were measured in German home-made preserve samples. Arsenic concen- trations showed a decrease during the period thought to reflect the discontinuation of the use of As-containing pesticides. However some of the older samples of home-made preserves of both fruit and vegetables contained more Cd or more Pb than in some of the more recent samples. A method was developed for the determination of Sn in canned fruits and vegetables.The measurements were made with an N-CH flame following extraction of the samples by - Journal of Analytical Atomic Spectrometry April Vol. R methylenedisalicylodihydroxamic acid complex with IBM K in tributyl phosphate. The organic phase was centrifuged and aspirated into the flame. The LOD and RSD for mg of Sn were. pg -' and.% respectively. Two papers reported the levels of elements in various Spanish fruits. Calcium K Mg and Na and Cu Fe Mn and Zn were measured in fruits. A Chinese paper reported the indirect determination of total water-soluble sugar in fruit and veg- etables by looking at the residual amount of Cu remaining after conversion of non-reducing sugars in fruit and vegetable samples.The use ofTi as a measure of soil contamination was described for Al Cr and Fe determination in vegetables. The authors reported that soil entrap- ment by plant tissues was often ignored when tissues were analysed and this lead to errors in the interpretation of results. They investigated the problem by taking plant tissues washing them in deionized H oven-drying or freeze-drying them grinding them and storing in glass bottles. Samples were obtained from different vegetable plots and the surface soil in each plot was sampled. Sub-portions of the ground plant tissues and soil were analysed for a number of elements by ICP-AES and ETAAS. Up to % of the Al % of Cr and % of the Fe of vegetable samples could be accounted for by soil particulate inclusion by the plant during its growth.The analysis of Pb in cucumber plants was reported. The first paper discussed the accumulation and translocation of Pb as monitored by ETAAS. Parts of the cucumber plants were dried at "C and then the dried samples were digested by using HN,-H,O followed by dilution. The samples were analysed by ETAAS with drying charring and atomization temperatures of and "C respectively. Each determination was followed by a s clean-up at "C. In the second paper ICP-AES was used to measure B Ca Cu Fe Mg Mn Ni Pb and Zn. The influence of Pb contamination and complexing agents on the metal uptake of the cucumbers was studied. In the presence of ETDA Pb contamination resulted in growth stimulation and higher Cu and Ni uptake. Addition of Pb to nutrient solutions containing citrate or C- resulted in reduced growth and higher Ca Mg Ni and Zn uptake. Papers byTahvonen describe the Cd and Pb content in selected fruits berries and vegetables on the Finnish market and the Cd and Pb content of Finnish breads. For the fruit berry and vegetable samples Ca Fe K Mg Mn and Zn contents were determined by FAAS after digestion with HNO,. For Cd and Pb in bread samples ETAAS with Zeeman background correction and NH HP as chemical modifier were used. The mean and median Cd contents in all bread samples analysed were and pg kg-l. The mean and the median Pb contents were and pg kg-'. The samples showed a very high variation in their Pb contents and the study showed that Pb in Finnish breads was much lower than that found in the late s. In contrast the Cd level was about the same as that found in the late s.The Cd content of rye breads was lower than that of other bread types studied. The same author has published levels for a range of trace elements in a total of Finnish bread samples. In total six bread types were investi- gated rye bread wheatflour content -% Finnish coffee bread wheat low ash French bread wheat low ash whole- wheat bread high ash mixed bread one wheat rye and or oat; mainly wheat and mixed bread two flour components unknown; mainly wheat. Rye bread had the highest mean elemental concentrations with the exception of Fe. French bread was found to have highest Fe content because of the Fe fortification of wheat flours. However the range of Fe contents in wheatbreads was wide - mg kg-l indicating that not all bakeries use fortified flours. Overall the levels of these elements in bread samples varied considerably within and between the different bread types. In a paper from Pakistan wheat and wheat by-products from that country were analysed to study the concentrations of essential or toxic elements.The analyses were carried by NAA and AAS. The results were compared with those from other countries. Pesticides and heavy metals were measured in German cereals by Tietz et al. Samples from the German harvest were investigated. Of the samples none were found to exceed the tolerance value. mg kg-l for Cd and Pb. The pesticide Lindane was found in <O% of the samples and DDT was found in %. Copper Fe and Zn were measured in tinned mussels by ICP-AES.The optimum conditions for RF power pump flow plasma gas flow and nebulizer gas flow as well as the observation height above the load coil were determined manually for each element since the authors found the Simplex method to be less than adequate. Cadmium Cr Co Cu Fe Mn Pb and Zn were measured in dried fish from Nigerian markets by FAAS. The method was used to investi- gate the possibility of surface contamination of fish due to poor handling practices. The results were discussed in terms of the effects of the concentrations found for the different metals on the health of the consumer. Contributions From Food Packaging Materials Food containers may contribute to the trace element content of foodstuffs. For example A in wines has been determined directly using ETAAS to investigate the migration of A from aluminium crown caps on wine bottles.The wine was diluted with H and measured at. nm. The use of Ar as purge gas improved the sensitivity by at least two-fold com- pared with that obtained when N was used. The use of % HNO as chemical modifier did not affect the results. The LOD was. pg -' with RSDs of. and.% for white red and fortified wines respectively. The contribution of A packaging materials and cooking utensils to the daily A intake was studied by Mueller et al. The levels of A in foods and beverages was determined at intervals during cooking or during storage by ETAAS. As anticipated higher amounts of A migrated when acidic products such as mashed tomatoes were cooked in aluminium pans. The storage of cola- type drinks in internally lacquered aluminium cans resulted in A levels of <. mg -'. In contrast coated aluminium camping bottles containing lime blossom tea acidified with lemon juice released < mg I-' within d.The Swiss authors of this paper stated that as most pans nowadays were made of stainless steel or Teflon-coated aluminium the average contribution of aluminium utensils to the daily dietary A intake in Switzerland - mg was estimated at <. mg. The effect of soft drink packaging on the A concentrations in tissues of rats was also reported. The objective of the study was to compare tissue levels of A in rats fed soft drinks packaged in aluminium cans or glass bottles; the levels were compared between rats fed soft drinks or distilled water. Rats fed canned soft drinks had significantly higher blood liver and bone A concentrations than rats that were given glass bottle soft drinks.There was % higher bone A concentration and % lower femur mass in rats fed aluminium canned soft drinks when compared with rats fed with distilled water. Polymers may contain low levels of chemicals used in their manufacture or else substances derived from them such as catalyst residues. Tin in unplasticized polyviny chloride P V C pipes used for conveying drinking water was measured by Zeeman effect ETAAS. Samples were suspended in % acetic acid using CaNO as chemical modifier to increase the ashing temperature and reduce inter- ferences. The method was reported to be quick and simple and as well as accurate and sensitive with an RSD of.%. An R Journal of Analytical Atomic Spectrometry April Vol. improved method for the determination of organotins in food surveillance was reported by Dominic et al.The authors reported that the use of the L'vov platform plus chemical modifier for measurement by ETA AS offered improved sensitivity and specificity over complexation-color- imetry and other methods which have been used for determi- nation of organotin in food simulants. The LOD for Sn in corn oil was ppb with a standard deviation of ppb. The recovery of Sn stabilizers spiked into corn oil at ppb was %. The method was used to test for leaching of Sn from PVC bottles stabilized with methyltin stabilizers. The results showed that the levels of methyltin presented no hazard for consumers. Trace elements from food contact polymers were measured by different techniques in a paper assessing the performance of the techniques for this application.The evaluation of an analytical method is best performed by using CRMs if available. However since no polymer standards were commer- cially available at the time of this paper the authors reported the use of in-house polymer RMs. The methods evaluated were a semi-quantitative microwave digestion ICP-MS method with NAA analysis used as a reference method and with some data obtained by LA-ICP-MS. The authors reported that the semi- quantitative ICP-MS method performed well where the requirements were wide element coverage and high sensitivity. A few elements were subject to interferences which necessitated cautious interpretation of the data. The inherent sensitivity of ICP-MS was also negated to some degree by the sample dilution which accompanied the microwave digestion since both HNO and HS were used to digest the polymers.The accuracy of the semi-quantitative mode was not exceptional but the method did achieve rapid multi-element analyses which were considered ideal for screening of polymers for trace elements prior to a fully quantitative analysis or migration experiments on targeted substances. The results for Co and Sb in an unknown polyethyene terephthalate PET were reported using a PET in-house polymer reference material for calibration. The values mgkg-I for Co were for semi- quantitative ICP-MS ; for quantitative ICP-MS ; for NAA ; and for LA-ICP-MS,. Similarly for Sb the figures were and. The results for these in-house RMs suggested that they provided a useful aid for validating the methods described in the paper.The authors stated that this type of RM would have great use now that recycling issues have generated new requirements for the use of contact polymers in food wrapping materials. Dietary Intake Studies. The daily dietary intake of Cu and Zn by several population groups in Belgium has been described. Daily elemental intake not including the contribution from beverages was calculated for these two elements and proved to be below the recommended daily allowances [National Academy of Sciences USA ] except for the Cu intake of macrobiotics. The values obtained in this study were compared with the scarce data on intake by similar groups from other countries. The influence of dietary factors on the trace elements reference values in tissues from the inhabitants of the European Community were described by Minoia et al.The study was carried out using a combination of techniques including ETAAS and HGAAS ICP-AES ICP-MS and NAA. In the absence of CRMs the control of accuracy was performed by determining each element by at least two independent analytical techniques. The results were considered satisfactory for differences which were < and % for analyte concentrations of > mg -' in the range - mg -l and < mg -' respectively. This Italian study concentrated on assessing the importance of beverages as a dietary factor influencing trace element reference values. The elements B Rb and Zn followed by Al Cu Mn and Sr were the elements with the highest concen- trations ranging from mg levels to hundreds of pg per litre in wines. Boron and Sr were highest in mineral waters; Al B Mn Rb and Sr in beers; Al B Mn Rb Sr and Zn in tea infusions; and Cu Mn and Rb in instant coffees. Overall beverages contributed significantly to the total dietary intake of elements such as Al Ag B Ba Co Li Mn Ni Rb Sb ScTh T U V and W. Corradini et al. analysed the heavy metal content of Aceto Balsamic Tradizionale di Modena ABTM. This type of balsamic vinegar was measured by FAAS using an air-C,H j a m e following predigestion with HNO overnight at room temperature. Digestion was continued on a sand-bath at "C and then the sample reduced by gentle boiling to near dryness. The HNO was again added lOml and digestion continued until approximately ml of the solution remained. Following rinsing with H the sample was heated again for min and then after cooling made up to ml with H and filtered.The filtrate was analysed without further dilution. Recoveries were nearly quantitative for Cd Cr Cu Ni Pb and Zn. The dependence of metal content on the age of the product was investigated. The ABTM is manufactured from cooked musts. Metal concentrations exceeded legal tolerances for both wine and wine vinegar but because only small amounts of ABTM are ingested the amounts of metals con- sumed were considerably below recommended dietary intake values. A duplicate diet study and one market basket study were used to investigate the daily intakes of alkaline earth metals in Japanese males. The elements were determined by ICP-AES. Some of the observed ratios defined as the element ratio in bone divided by the respective element intake ratio in Japanese males were as follows for Ba,.; for Mg,.; and for Sr,. A Polish study determined trace element levels in domestic food products in particular milk and milk products.The elements investigated were Cd Co Cr Cu Se Mn Ni Pb and Zn. The experimental data indicated that in some powdered milks the levels were higher than recommended for Cd and Pb the recommended values being. and. mg kg-l respectively. The same group investigated the Cd Hg and Pb intake from canteen diets. A survey had been conducted during in the Lublin area to determine dietary intakes from food served in a student canteen. Diets were collected in each of the four seasons over a period of d. The data indicated that the average intakes of Cd Hg and Pb did not exceed the tolerable weekly intakeTWI recommended by the FAO-WHO reaching up to % Cd % Hg and % Pb of these limits. However on an individual basis some of the intakes may approach % of the daily intake limits for Cd and Hg. For Pb the intake ranged from to % of the daily intake limit. Calculated total diet daily intakes were compared with intakes published for other countries in a study of different population groups in Burundi Africa. Recommended daily intakes RDIs National Academy USA were met for Cu and Zn however for Se especially in rural populations there was a risk of deficiency with an observed daily intake of pg. The importance of different types of food in daily intake was discussed. For Cu legumes proved to be an important source whilst for Se fish contributed in large part to the dietary intake.The Ca Cu Mn and Zn levels as well as non- starch polysaccharide and phytate contents of locally grown and prepared African foods were measured. Calcium Cu Mn and Zn were measured by FAAS. On a fresh mass basis legumes and animal products had the highest mineral content. In contrast cereals had the lowest Ca and Cu content with roots tubers plantain and vegetables having the lowest Journal of Analytical Atomic Spectrometry April Vol. R Zn content of all. The authors felt that the addition of foods such as peanuts fermented locust bean seeds or fermented kapok seeds to soups and stews and the use of small fish would increase the mineral content of the dishes consumed. The question of Cu Se and Zn deficiencies in the diets of French men was addressed in a paper by Pelus et al. Copper Fe Mn Se and Zn were determined in liophilized daily diet samples by ETAAS. Gas chromatography-MS was used for Se determinations. Whilst Fe and Mn intakes appeared to be adequate the requirements recommended by the National Academy of Sciences USA were not met for Cu Se and Zn.The dietary intake of Cd and Pb amongst the Japanese population was compared for men and women. Cadmium intake was greater for men than for women but there was no difference in the intake of Pb for the two sexes. The Pb intake had decreased steadily for both men and women in the last years and this decrease was greater than that for Cd. A Chinese paper reports the determination of Cd Hg and Pb in Chinese total diets. Cadmium and Pb were determined by ETAAS and Hg by CVAAS using pressure bomb digestion.The NIST SRMs spinach and oyster tissue were used as RMs and in total cooked and prepared diet composites were analysed. The LODs for Cd Hg and Pb were.,. and. pg kg-l respectively. Characterization Studies Coni et al. investigated the role of manufacturing processes in the distribution oftrace elements in milk and dairy products. The results showed considerable differences between the levels of trace elements in raw milk and those in derived products. Quantitative measurements for Al Ba Cd Co Cr Cu Fe Mg Mn Ni Pb Pt Sr and Zn were made by ICPAES. In a similar paper by the same group the data are interpreted in terms of animal feeding the season of sample collection environmental conditions as well as the manufactur- ing processes. All were deemed to play a key role in the distribution of trace elements in raw cow’s milk and cheese products. Both FAAS and ETAAS were used to determine trace element levels in raw milk.The milk was produced from cows under two different feeding regimes using the technique of linear discrimination analysis. The authors were able to confirm fully the separation between the two types of milk on the basis of the minor and trace element con tents. A large variation in the trace element composition of tea samples was found in a paper by Lamble and Hill. The paper reported a microwave digestion method for tea leaves using an open focused microwave digester. The elements Al Ba Ca Cu Mg Mn and Zn were determined using ICP- AES. Excellent agreement was obtained for the certified values of a reference tea sample.The results for the commercial teas were discussed with reference to both existing literature values and country of origin. Principal components analysis PCA was used to group Belgian breads according to their mineral composition and to uncover any hidden relationships in the data tables. A distinc- tion could be made between a group of white breads and a group of wholemeal breads using data for seven minerals Al Ca Cu Se K Mg and Zn. Data for Cu Se Mg Mn and Zn from cocoa masses was evaluated by PCA in order to build a model for the determination of geographical origin and process effect. However the contamination of cocoa masses originating from the grinding tools prevailed over geographical origin variability. Chinese workers have compared mineral element contents from different types of ginseng using ICP- AES. A total of elements were measured and the results indicated that the elemental content varied with ginseng type location and place of origin. Levels of Cd and Pb in all R Journal of Analytical Atomic Spectrometry April types of ginseng were far below toxic doses.The multi-element data would provide a foundation for the optimum selection of superior types of ginseng. A review of methods for assessing the authenticity of orange juice has been given by Robards and Antolovich. The paper critically examined analytical approaches used to measure juice integrity and to detect various forms of adulter- ation including the measurement of vitamins and minerals and total trace metal measurements using ICP-AES and ICP-MS. Criteria were developed to detect the presence of pulp wash in orange juices. Using PCA levels of Ca and Mg as well as hesperidin narirutin flavonoid and poly- phenol data gave a semi-quantitative estimate of true orange juice content.Trace metal profiles in green coffees were investigated using ICP-AES and ICP-MS for multi-element data determinations. The authors stated that it was highly likely that the levels of some elements were indicative of the growing plants’ micro-environment and could therefore provide a means of differentiating coffees of different geographical origin. Pattern recognition analysis was used to classify wines from North-western Spain with certified brand of origin certificates. Data was processed using multivariate chemometric techniques involving cluster analysis PCA discriminate analysis K-near- es t neighbours and soft independent modelling of class analogy to develop a typification for wine samples in this region. By using Li and Rb as key features a nearly correct classification was achieved. Metal ions were determined in Spanish wines from Granada by Olalla et al.The results showed low K levels and high Fe and Mn levels in the wine. After using variant analysis no significant variations were observed for the wines from the different areas studied that could be deemed due either to altitude or proximity to the sea. Day et al. have been determining the geographical origin of wine using analysis of both elemental and isotopic composi- tion. Stable isotope analysis of grape juices and fermented products involved H-NMR spectroscopy and iso- tope ratio MS was carried out in combination with total elemental determinations using FAAS and ETAAS. An exhaus- tive statistical evaluation of the x data set produced was carried out using analysis of variants and PCA.The classification of samples in typical appellations was carried out by discriminant analysis and nearly % correct classification was achieved. Cobalt Cr Cu Se Mn Ni Pb and Sn were measured in virgin olive oils obtained by using different extraction systems. The results obtained for the different trace elements were analysed by multivariate statistical analysis to evaluate the influence of the production systems on the oil character- istics. The Fe content of the oil was linked to the extraction methodology although variation was considerable. No correlation was observed between the extraction procedures and the content of the other metals. Reference Materials and CollaborativeTrials Trace amounts of A in biological RMs were measured by ETAAS. The homogeneity of Al at the ppm level in a set of RMs was determined. The materials included bran wheat flour gluten whole egg powder whole milk powder meat powder starch cellulose corn kernel and corn stalk. Reproducible values were obtained which indicated that all the material studied could be considered to have a homogenous distribution of A between samples at test size portions of mg. For all of the materials except milk egg and meat HF was required in addition to HNO to effect complete dissolution. A new batch of CRM skimmed milk powder supplied by the European BCR Measurements and Testing Programme Vol. was characterized for Ca Cu C- Fe K Mg PO,- N, Na and Zn.The material was prepared by spray drying and its homogeneity and long-term stability were verified. Flow injection was used with HG-AAS to determine As and Se in two RMs. The RMs were NIST SRM A and A spinach and tomato leaves respectively. The samples were digested with HN,-HS,-HC using a reflux column. After cooling HC was added the digests diluted with H,O and then the reducing agent consisting of % KI-% ascorbic acid was used to reduce AsV to As"'. A second portion of the diluted digest was heated with HC in a water-bath at °C for min to reduce SeV to SeiV. Using % HCl as the carrier stream the FIA system swept the sample from the injection loop to a mixing coil where it was reacted with a reductant solution of NaBH,-NaOH. The LODs for As and Se respectively were. and. ng ml-I and the results agreed well with certified values.The preparation and homogeneity characterization of RMs was described in a paper by Ihnat et al. The RMs were bovine muscle powder corn starch hard red spring wheat flour soft winter wheat flour whole milk powder wheat gluten corn bran Durham wheat flour whole egg powder and microcrystalline cellulose. Homogeneity tests were performed for elements using FAAS and ETAAS. Aluminium Ca Cu Fe K Mg Mn Na Sr and Zn were determined by FAAS after acid digestion. Cadmium Co Ni and Pb were measured after separation and preconcentration by ETAAS. In addition an extensive set of analytical results obtained from inter- laboratory co-operative characterization measurements were used to provide homogeneity estimates for other elements. In total acceptable homogeneity data for elements was obtained. Jorhem reported the results of an inter- laboratory study for Cd Cr Cu Fe Ni Pb and Zn in foodstuffs.The samples were measured by FAAS and ETAAS after dry ashing. The results were discussed in detail. The precision of the method was acceptable for all elements except for Ni but there was no other collaboratively tried method that provided as good or better results for these metals. The study included five different foods liver paste apple sauce minced fish wheat bran and milk powder as well as two composite diets. A single analysis was carried out on each sample by each laboratory. An assessment of the analytical quality control procedures for Table ANALYSES OF FOODS AND BEVERAGES developing methods for determining toxic traces elements in Chilean seafoods was described. Levels of Cd Cu and Hg were determined in fresh and canned molluscs caught in areas off the Chilean coast. Analyses were performed by NAA ASV and CSV as well as AAS.The data obtained by these analyses and the analysis of SRMs were comparable. Satisfactory results were obtained from inter-laboratory com- parisons. Longbottom et al. report the results of a joint US Environmental Protection Agency-AOAC inter- laboratory method validation study. The study was conducted to determine and compare mean recovery and precision data using ICP-MS analyses for trace elements in reagent water drinking water and groundwater. Mean recoveries for spikes were generally -% with between-laboratory RSD of %. Recoveries for Ag were low in all matrices at concen- trations greater than pg -'.The HN digestion pro- cedure used was comparable in accuracy and precision to a mixed acid digestion described in United States Environmental Protection Agency USEPA Method. The reported method was adopted as a first action by AOAC International. Finally direct ETAAS was used to determine Pb in edible oils and fats. The IUPAC Commission on Oils Fats and Derivatives undertook the development of a method and the oversight of a collaborative study for the determination of Pb in oils and fats. Various types of graphite furnaces were used with or without platform. Twenty-three collaborators from countries participated in the study and the test materials were soya bean oil and cocoa butter containing Pb at three concen- tration levels. Collaborators were instructed to analyse each material at each level in duplicate and to report both results. A total of collaborators returned the results for the study. After data from laboratories that did not follow instructions were excluded only sets of data were evaluated statistically. On the basis of this collaborative study a direct method for determining Pb in oils and fats has been adopted as a first action by AOAC International as a IUPAC-AOCS-AOAC method.The method involves heating samples at °C and then allowing them to equilibrate. After shaking a portion of samples was mixed with % lecithin solution in cyclohexane as chemical modifier and then analysed by ETAAS. Reproducibility and repeatability as RSD were.% and <.% for soya bean.% and Y for soya bean for cocoa butter. Element Ag Ag A A A CerealsTechnique; atomization; Matrix AA;ETA;L Mushrooms Food packaging Wine Foods AA;F,air-CH,;L AA;-;L A A;ETA; L AA;ETA;L Sample treatment comments Reference Following sample digestion Ag was extracted using diphenyldithiocarbamate in IBMK. The RSD was between. and % for sample concentrations up to. pg g- Crushed samples were dry ashed at "C,. The leaching of A from soft drink packaging was re-dissolved in mol -' HNO, re-ashed and finally dissolved in mol - HNO ml investigated by analysis of rat tissues. There was a % higher bone A content and a % lower femur weight in rats fed the A canned soft drinks compared with rats fed distilled water A procedure was devised to determine migration of A from A caps. The use of % HNO as chemical modifier did not influence results.The wavelength was. nm ashed using HNO,.With analysis at. nm the recovery of the method was better than % in Polish Samples were dry ashed at "C for h or wet Journal of Analytical Atomic Spectrometry April Vol. R Matrix Sample treatment comments An FI system connected to the ETAA spectrometer autosampler was used for slurry preparation addition of modifier dilution and homogenization. The arrangement could be used to perform standard additions A variety of sorbents for preconcentration were evaluated. The best results -fold enrichment were given by silica gel or Amberlite IRA modified by Chrome Azurol S. Various potential interferents were discussed packaging was reported. The contribution to the average daily dietary intake in Switzerland was calculated A was determined in lemonade and beer stored in bottles or A cans.The A level in the beverages stored in A cans was up to times those stored in bottles. The wavelength of measurement was. nm in Czech determined. All of the samples required HF to be included with HNO in the digestion leaves. It was estimated a ml infusion contributed - and -% respectively of daily A and Mn intake in Japanese contained lower levels of A than those in previously published data. The determination of A at. nm was used to measure the carmine content of cherries. Carmine- containing cherries contained pg g-' whereas those without carmine contained.-. pg g- ' in Japanese Samples were microwave digested using HN,-H,O, + in a closed vessel. Direct measurement against aqueous standards was used for calibration acid leachable total dissolved chelation extractable and non-extractable An on-line microwave digestion-FI-ETAAS method was described. Samples p were simultaneously injected with p of mol -' HNO into a PTFE reactor inside a microwave oven.The digest was collected in the autosampler A was preconcentrated using a microcolumn packed with Chromotrope B immobilized on AG-l-X ion exchange resin. The LODs for FAAS and ICP- MS were and. ng ml-' respectively Optimum conditions for the ashing step were discussed in Chinese A detailed study of the effect of soil inclusions on the accuracy of Al Cr and Fe determinations was described. As much as % of the Cr found in vegetables could be accounted for by soil entrapped within the plant tissues Addition of C via MeOH or NH ,CO to sample solutions increased As and Se signals by - to -fold.The enhancement was reported to be species specific A review containing references on arsenic determination in food using atomic spectroscopy A study of A leaching from food and beverage. The homogeneity of selected Canadian RM's was Both A and Mn were determined in tea and tea It was reported in a survey of Indian foods that these Al was speciated into the following fractions-total Reference Element A Milk desserts AA;ETA;Sl A Water A Packagmg materials AA;ETA;L A Beverages AA;-;L A Biological RM's A Tea AA;ETA;L AA;ETA;L AA;ETA;L A Foods A Canned cherries AE;ICP;L AA;ETA;L A Bread fish A Water A Shellfish c AA;ETA;L MS;ICP;L AE;DCP;L AA;ETA;L A Water AA;F;L MS;ICP;L A Beer A Vegetables AA;ETA;L A A;ETA;L As Shellfish MS;ICP;L As Foods As Cows milk AA;ETA;L AA;H y;L -;ICP;L A A;H y ;L A dry ashing procedure was described that yielded an LOD of. ng g-' and a recovery of approximately %. Possible interferents were discussed.The presence of tertiary amines was reported to enhance the As and Se ions and significantly reduce chloride polyatomic interferences As Foods MS;ICP;L C R Journal of Analytical Atomic Spectrometry April Vol. Element Matrix As Foods MS;ICPL Sample treatment comments prior to determining As Hg and Se by HG-ICP-MS was described. Samples were digested overnight with HNO, diluted to ml whilst maintaining an acid concentration of % v v and introduced using continuous flow HG. Problems with As recovery were described A single microwave digestion method was developed for the detection of As Cd and Pb in a variety of seafood products. Analytical criteria of merit were calculated chickens fed arsanilic acid and roxarsone were found in some cases to exceed the US FDA whole egg tolerance An unusual study was reported in which levels of As Cd and Pb were measured in preserves dating back to. As levels were higher in the early samples as surprisingly were some of the Cd and Pb levels in German Samples were digested using HN,-H,S,-HC under reflux and analysed using an FI AAS method.The LODs were. and. ng ml-l for As and Se respectively arsenobetaine by HPLC-ICP-MS was described. Recovery was of the order of % Various dissolution methods were compared. Using microwave furnace ashing with ashing aid an LOD of. ng g-' was obtained Samples were enriched by co-precipitation with FeOH , centrifuged and analysed using HG to improve sensitivity. An LOD of ng ml-' was reported An alarming report on As poisoning as a result of natural contamination by As"' and AsV of drinking water in the West Bengal region of India. It was estimated that at least people were drinking water above the WHO recommended level with showing symptoms of the late stages of As toxicity Samples were digested using microwave techniques then analysed by a number of procedures including the two ICP methods.The ICP methods gave the best precision. The optimum conditions for determining Be using a tungsten atomizer were discussed. Addition of AlNO as modifier eliminated Ca and Mg interferences. At. nm an absolute LOD of. pg was reported matrix method for identifying adulteration of orange juice using pulpwash in French.The determination of Ca was used as an indirect measure of total acidity in Chinese Raw milk samples were soured so that the fat and casein precipitated filtered and analysed using ETAAS with. YO HPO as chemical modifier Cd was determined using APDC as chelating agent in Chinese Various vinegars were evaporated to dryness ashed at "C the ash redissolved in diluted HC :l and Cd Ni and Pb analysed using FAAS. LODs were at. nm at nm and at nm ng ml-' for Cd Ni and Pb respectively. Significant losses during ashing were reported determined by suspending in % v v EtOH and slurry sampling using ETAAS. LODs for Cd and Pb were. and ng g-'.Chemical modifiers were Pd and Cu NH for Cd and P - for Pb Samples were microwave digested. The highest level detected was. ng g-' A sample digestion method that could be utilized.The concentrations of As found in eggs from A procedure to extract clean up and determine. The measurement of Ca and Mg was part of a Various cereals and cereal based products were Reference C. As As As Seafood Chicken eggs Cherry preserves AE;ICP;L MS;ICP;L AA;ETA,L AA;-;L AA;-;L As Food CRMs As As As Seafoods Childrens' food Water MS;ICP;L MS;ICP;L AE;ICP;L As Water AA;ETA;L AA;Hy;L B Foods AE;ICPL MS;ICP;L Be Water AA;ETA;L Ca Orange juice AA;-;L Ca Cd Soda water Milk AA;-;L AA;ETA;L Cd Cd Soy sauce Vinegar AA;F;L AA;F,air-C,H ;L Cd Cereals AA;ETA;SI Cd Seafood AA;ETA;L Journal of Analytical Atomic Spectrometry April Vol. R Element Matrix Cd Seafood Sample treatment comments. The development of methods for and the results of a survey of Cd Cu and Hg in Chilean seafood were given.The results of a -day trial of Cd Hg and Pb in diets served in a Polish student canteen were reported. Levels of both Cd and Hg approached the FAOIWHO tolerable daily intake in Polish See As ref. Reference AA;-;L Cd Student food AA;-;L Cd Seafood Cd Foods AE;ICP;L A A;ETA;L M S;ICP;L AA;CV;L Sample g was digested under reflux with concentrated HN,-% H + and analysed using ETAAS Cd and Pb and CVAAS Hg in Slovak Samples were washed chopped dried to constant weight ground then treated with EtOH ml concentrated H,Oz ml and NH,H PO mg before final dilution to ml. The solutions were stirred continuously whilst pl portions were taken for analysis at. and. nm for Pb and Cd respectively. The effect of Cd Cr and Pb contamination in water and aquatic plants on levels in buffalo milk was investigated See As ref. ' Preconcentration factors of -fold were obtained using both -hydroxyquinoline and cupferron on activated C yielding LODs of. and. ng g-' of Cd and Pb in dry material.The effects of pH and decomposition method employed were investigated FI preconcentration using NaDDC in IBMK was described. LODs of. pg -' were quoted Samples were ground then mixed with a combined chemical modifier of Ca NO ,-LaNO ,- NH NO all.% and % EtOH dried and introduced using a home-made solids injection device onto a L'vov platform. Using standard additions recoveries of -% were reported in Chinese Total Diet Survey were reported along with details of the methods used A survey of Finnish breads showed Cd levels had remained constant and Pb levels had declined since surveys in the 's. Zeeman effect ETAAS with NHH,P chemical modifier were used for the measurement A platinum loop atomizer was used to determine Cd Pb and Zn Samples were dried ground and suspended in.%Triton X-% H,O,-l% HNO,. Aliquots pl were analysed using wall atomization at. and nm for Co and Ni respectively yielding LODs of and ng g-' Total Cr was determined following digestion using HN,-HCl-HF whilst Cr"' was dissolved in. mol -' NaOH. Using a Pd-Mg chemical modifier the LODs were. and. pg -' respectively. Detailed information on method development is given Cr"' at an LOD of. pg -' was measured using ion chromatography coupled to ICP-MS in Japanese. The results for Cd Hg and Pb in the Chinese See Cd ref. Cr was determined following extraction using diphenylcarbazide in isobutanol.The LOD was ng g-' See Al ref. Samples were digested in HNO, evaporated to dryness and the chloro complexes of Cu Fe and Zn formed by treatment with moll-' HC. The complexes were then passed through an anion exchange column and eluted using HCl-HNO, evaporated and redissolved in % HNO prior to analysis by FAAS AA;ETA;Sl Cd Vegetables Cd Buffalo milk AA;-;L Cd Cherry preserves Cd Vegetables AA;-;L AA;F;L AA;F,air-CH,;L AA;ETA;S Cd Rice Cd Cereals plants AA;ETA;L AA;CV;L Cd Foodstuffs Cd Bread A A; ETA; L AA;ETA;L A A; ETA; S c Cd Apricots c o Foods Cr Animal feed A A;ETA;L Cr Water M S;ICP;L Cr Buffalo milk Cr Cereals AA;-;L AA;ETA;L Cr Vegetables c u Infant milk formula AA;ETA;L AA;F,air-C,H,;L R Journal of Analytical Atomic Spectrometry April Vol. Reference C Element Matrix Sample treatment comments Samples were analysed using a slotted-tube atom trap in Chinese A rapid method for the determination of Cu in egg white and yolk involving closed PTFE vessel microwave sample dissolution was described in Chinese STPF ETAAS was used to measure Cu in port and Madeira wine.The LOD was. pg -' in the undiluted sample HNO in % EtOH stirred and a pl portion pipetted into a pyrolytically-coated tube. Analysis was at. nm with D background correction See Cd ref. The effect of infusion procedure on the leaching rate Cu was determined following on-line FI Dried ground sample was sonicated with.% of Cu Mn and Zn was studied in Polish preconcentration using DDC to chelate with the Cu the complex then being adsorbed onto the walls of knotted reactor tubing over a period of s prior to elution using IBMK.The LOD was. The fractions of Cu Se and Zn available for human. pg -' absorption were studied by an in vitro method that simulated human gastric and intestinal absorption. Se species were separated by precipitation and gel-permeation chromatography Wet and dry ashing were compared for the determination of Cu and Fe in musts. Wet ashing was found to give low recoveries for Fe Brazilian sugarcane spirit in Portugese Various methods for overcoming interferences were discussed in Chinese Cu was determined in samples of Aguardente a Cu Sn and Zn were determined in canned foods. see Cu ref. Samples were vaporized in a graphite cup and the gases passed through an inlet hole into an integrated contact furnace placed directly above the cup where atomization took place. Slow heating and atomization under reduced pressure were possible and were utilized to differentiate between inorganic and porphyrin bound Fe Between and mg of sample was introduced through an enlarged hole into a pyrolytically coated tube. Using "C ashing without platform or modifier an LOD of pg g-' was achieved at. nm See Cu ref. See Al ref. Samples were diluted to ml then analysed at. nm using FAAS. Recoveries were approximately % in Chinese beverage. Digestion was achieved using mol -' NaOH and H in Chinese Samples were digested using HN in a pressurized system. Using Pd as chemical modifier allowed an ashing temperature of "C. An STPF with pyrolytically coated tubes was used in Chinese Ge was determined in Ganoderma a Chinese See As ref. C See Cd ref. Convection and microwave heating were compared for sample dissolution. No significant differences in digestion efficiency were observed although the microwave was much quicker See Cd ref. See Cd ref. c u Rice AA;F,air-CH,;L c u Egg AA;ETA;L AA;ETA;L c u Fortified wines c u Biscuits bread A A;ETA;Sl c u c u SeafoodTea c u Rice water c u Mussels AA;ETA;L AA;F;L AA;Hy;L c u Must AA;-;L c u Spirits c uTinned foods AA;-;L AA;F,air-C,H,;L Fe Infant milk formula Fe Foods AA;F,air-C,H ;L AA;ETA;L Fe Pasta AA;ETA;S Fe Musts Fe Vegetables Ge Beverages AA;-;L AA;ETA;L AA;F,air-C,H ;L Ge Ganoderma AA;ETA;L Ge Foods AA;ETA;L Hg Foods Hi Seafood Hg CRMs MS;ICP;L A A;CV;L AA;-;L C Hg Student food Hg Foods AA;-;L AA;ETA;L AA;CV;L AA;-;G Hg Oils.The design of a gas cell for use with specific AA spectrometers was described in detail. The design allowed determinations at ng Hg in Russian An on-line FI microwave digestion system coupled to a dedicated FI Hg analyser was described. The system gave an LOD of ng -' AA;CV;L Hg Water c Journal of Analytical Atomic Spectrometry April Vol. I R Matrix Sample treatment comments Samples were digested using HNO-HSO at "C KMn was added and digestion continued. Then KS was added and the solution brought to boiling cooled NaC-hydroxyammonium sulfate added and an Sn" salt added to generate elemental Hg. The LOD was. ng g-' See Cd ref. Reference Element Fish AA;CV;L Hg Hg Foods Hg Mushrooms Hg Foods K Flour improvers AA;ETA;L AA;CV;L AA;CV;L Up to mg kg- of Hg were found in mushrooms around the Polish city of Gdansk in Polish.The average weekly intake of Hg in the Italian diet was assessed in Italian. The flour improver potassium bromate was extracted from flour using H filtered cleaned up using Bond Elut columns and determined using coupled HPLC-ICP-MS. The method yielded an LOD of pg kg- ' See Ca ref. See Al ref. See Cu ref. The concentration of Mn in a wide range of foods from Northern Poland was measured using dry ashing followed by FAAS in Polish An on-line FI system involving preconcentration on Dowex resin and elution using NH C- ammonium citrate was described. Measurement was at. nm and an enrichment factor of was achieved See Cd ref. See Co ref. Contamination and Pb retention by curd were thought to be the source of variations in Pb content in Manchego cheeses Pb species were extracted as DDC complexes derivatized using a Grignard reagent and measured by capillary GC-MIP.Trimethyllead was ubiquitous in all French wines examined See Cd ref. An on-line microwave digestion FI-HG-AAS system operating at. nm was described. A HN,-H,O mixture was the digestion medium and LODs of pg -' for liquids and ng for fruit were reported Pb was determined at nm using Zeeman-effect background correction,. YO Pd solution as the modifier and a Photron Superlamp as the source. This arrangement yielded an LOD of - pg See Cd ref. See Cd ref. See Cd ref. Samples were spiked with ' Pb microwave digested and the ' Pb:'" Pb determined by ID-ICP-MS using ultrasonic nebulization. Good recoveries for CRMs were obtained and the LOD was. ng g-' infant formula An on-line FI system for sample dilution and internal standardization was coupled to ICP-MS.The results for on-line ID on-line standard additions and external calibration were compared. The favoured results were from the standard additions approach. Full experimental details were given See As ref. AA;CV;L MS;ICP;L Mg Orange juice Mn Tea Mn Tea Mn Foods AA;-;L AA;ETA;L AA;F;L AA;-;L Mo Water AE;ICP;L Ni Vinegars Ni Foods Pb Cheese AA;F,air-C,H,;L AA;ETA;Sl AA;ETA;L AE;MIP;L Pb Wine Pb Milk Pb Beverages fruit AA;ETA;L AA;Hy;L,Sl AA;ETA;L C Pb Food CRMs AA;F,air-C,H,;L AA;ETA;Sl MS;ICP;L AA;-;L Pb Vinegars Pb Cereals Pb Student food Pb Infant formula Pb Wine MS;ICP;L Pb Seafood AE;ICP;L A A;ETA;L AA;ETA;L AA;ETA;L M S;ICP; L A A,CV;L Pb Foods See Cd ref. See Cd ref. The results of an AOAC collaborative study were reported. Samples were heated to °C allowed to equilibrate a portion taken and mixed with a chemical modifier of % lecithin in cyclohexane and analysed by ETAAS at. nm analysed using Zeeman-effect ETAAS with a L'vov platform.The LOD at. nm was. ng ml-' Wines were diluted -fold with % HNO and Pb Vegetables Pb Fats oils AA;ETA;L Pb Wine R Journal of Analytical Atomic Spectrometry April Vol. Element Matrix Pb Cereals Pb Buffalo milk Pb Cherry preserves Pb Peach leaves rice Sample treatment comments Samples were digested and Pb extracted using NaDDC in CCl,.The LOD was. ng g-' See Cd ref. See As ref. Samples were digested with + HN,-HClO, evaporated to dryness and redissolved in mol -' HCl. Using FI this solution was mixed with a stream of % nitroso-R-salt in mmol -' NaOH and.% NaBH and the resulting hydrides determined by HGAAS.The LOD was pg I-'. The design of a portable Pb detector based on a tungsten coil atomizer fibre optics and a CCD spectrometer was described See Cd ref. Amberlite XAD- was functionalized by coupling it to salicylic acid. The resulting resin was used to preconcentrate Pb and Zn simultaneously A high-performance HCL high efficiency nebulizer and a slotted-tube atom trap STAT gave LODs of. ng ml-' at nm in Chinese cucumber plants was investigated. Microwave digestion was used for sample decomposition Samples were digested in a microwave using HNO and V,O,.The LOD was. ng ml-' See Cd ref. The accumulation and translocation of Pb in Reference C lC C C C R A A;ETA;L AA;-;L AA;-;L AA;H y;L Pb Biological samples A A;ETA;L Pb Pb Vegetables Water AA;F;L AA;F,air-C,H,;L Pb Water AA;F;L Pb Cucumber AA;ETA;L Pb Foods AA;ETA;L Pb Foods AA;ETA;L AA;ETA;L A A; ETA; L AA;ETA;L AA;F;L A A; CV; L Pb Pb Pt Bread Apricots Water See Cd ref. See Cd ref. lC Pt was preconcentrated on-line using FI with an alumina microcolumn for measurement by FAAS and off-line using the same arrangement but determination by ETAAS.The respective LODs for -fold FAAS and -fold ETAAS preconcentration factors were. mg -' and. pg -'.Various possible interferents were studied preconcentration on a cation-exchange resin. The method LOD was pg -' S-containing compounds were determined using a GC-AE detector See As ref. See As ref. C See As ref. C Sample was wetted mixed with glycerin Ra was determined by ICP-MS following pg ml-' Cu % MgNO and % HNO, diluted and portions of the resulting suspension analysed by Zeeman ETAAS in Chinese.The results of a survey of Se in fish from South Eastern Spain were reported Inorganic Se species were separated using HPLC with a potassium hydrogenphthalate mobile phase saturated with NiOH ,.The results of an interference study were reported HPLC-ICP-MS and isotope ratio analysis performed on the separated species. The LOD was ng g-' Headspace GC-AED was used to determine organoselenium species in garlic and garlic preparations Four Se species were measured using ion exchange See Cu ref. Ra Water M S;ICP;L S Garlic AE;-;L Se Se Se Se Shellfish M S;ICP;L Foods MS;ICP;L Foods MS;ICP;L Wheat flour wild cabbage AA;ETA;Sl Se Se Fish AA;Hy;L Selenium supplements AA;ETA;L AA;F;L Se Foods MS;ICP;L Se Se Se Garlic AE;-;G MS;ICP;G Mussels AA;ETA;L AA;F;L AA;H y;L Nutritional supplements A A;H y;L Selenomethionine was determined using HPLC- thermochemical HGAAS following derivatization with l-fluoro-,-dinitrobenzene and extraction with diethyl ether. Recoveries from supplements were of the order of % Following wet digestion with HNO, quantification was performed by on-line FI-HG-ICP-MS using isotope dilution for calibration Se Wheat M S; IC P; L Journal of Analytical Atomic Spectrometry April Vol. Table continued Element Matrix Se Human milk Se Se Se Se Se Se Se Se Sn Food RMs Garlic Fruit juices Infant formula Garlic rice teaTechnique; atomization; Sample treatment comments AA;ETA;L A A; ETA; L Water AA;H y;L Chinese chives garlic onion AE;-;L Broccoli garlic onion AE;-;G Shellfish Sn Food simulants Sn Fruits vegetables Sn Fruit vegetables AA;Hy;L AA;ETA;L AA;ETA;L A A;ETA;L AA;ETA;L Variations in Se content of human milk at different stages of lactation were investigated using Zeeman- effect ETAAS with Pd modifier.The results suggested Se status is adequate in Niger the country under study See As ref. Se species were preconcentrated on Tenax in a cryogenic trap prior to quantification by GC-AED. Dimethylselenide was the major species in garlic-borne breath present at sub-ng ml-' concentrations FI was used to dilute add modifier [PdNO ,] and deliver filtered sample to the autosampler of an ETAA spectrometer operating at nm. The LOD was pg I-' Sample. g was microwave digested with. ml of % HNO, mixed with. ml of.% CuNO and. ml of.% MgN and diluted to ml prior to analysis by ETAAS.The LOD was ng g-' residue was then dissolved in ml of.% HC further diluted in HCl-H and analysis conducted using FAAS with a STAT at nm SetV SeV and trimethylselenium were speciated using on-line anion exchange HPLC-microwave oven digestion-HGAAS with LODs of.,. and. ng respectively Another paper describing the application of headspace GC-AED with a total of nine Se-containing species identified in the target samples Further discussion of the application of headspace GC-AED for Se speciation in plant materials. Extraction methods such as solid phase extraction and thermal extraction were also considered during the presentation Butyltin species were extracted by sonicating samples for h in. mol -' HC. Species were then reduced by NaBH, cryogenically trapped separated by selective volatilization and measured by quartz furnace AAS. LODs were approximately - ng g-' wet mass A method for determining organotin compounds in food contact plastics using ETAAS with L'vov platform and chemical modifier was described.The LOD for Sn in corn oil a fatty food simulant was ng g-' ETAAS with L'vov platform and titanium coated tubes for analysing the acaricide tricyclohexyltin Fenbutatin oxide was extracted using butanone cleaned up using a silica gel column and measured at. nm using ETAAS with Pd chemical modifier in Japanese. The use of ,'-methylenedisalicylohydroxamic acid complex with. mol -' IBMK in tributylphosphate for Sn extraction was detailed Sn was determined in PVC pipes designed for carrying drinking water.The sample was suspended in % CH,COOH and Sn measured using ETAAS with CaNO as modifier in Chinese Butyl- cyclo- octyl- and phenyltin were determined in wines by GC-AAS following extraction with.% tropolone in % diethyl ether-pentane and subsequent Grignard derivatization. More than % of the samples tested contained at least one of the species AA;F,air-CH,;L Digestion was achieved using HN-HC the A method was developed using Zeeman effect AA;F,air-C,H,;L See Cu ref. AA;F;L FI with an on-line ion-exchange column was used to preconcentrate Sr. The LOD was ng ml-' Sn Canned fruits and vegetables AA;Hy;L Sn Water AA;ETA;L Sn Wine Sn Tinned foods Sr Water AA;-;L Reference c C R Journal of Analytical Atomic Spectrometry April Vol. AA;F,air-C,H ;L Element Sr Matrix Milk milk powder Sample treatment comments A method for determining stable Sr and its application in a survey of milk from dairies in different geological areas of Germany was described and the radiological importance discussed in German A complex method was outlined which involved preconcentration of Zn on a liquid emulsion membrane and then desorption by applying a static electrical charge.The LOD was. ng ml-' in Chinese see Cu ref. See Cu ref. See Cu ref. Reference. c C Zn Beverages AA;F,air-C,H;L Infant milk formula Tea Mussels AA;F,air-C,H,;L AA;ETA;L AA;F;L AA;Hy;L AA;-;L AA;F,air-CH,;L AA;F;L Zn Zn Zn Zn Zn Water Wine See Pb ref. A standard additions FAAS method for routine See Cu ref. See Cd ref. C control of Zn in wine was proposed Tinned foods Apricots AA;F,air-C,H ;L AA;ETA;L Zn Zn MULTI-ELEMENT ANALYSIS Certified Reference Materials and InterlaboratoryTrials Various RMs MS;ICP;Sl Slurry sampling was conducted by means of ultrasonic sampling-ETV-ICP-MS with particular emphasis on investigating transport efficiency and the use of O ashing. The use of tygothane tubing as carrier was proven to be beneficial Analysis by direct laser ablation of the samples was found to give results inferior in accuracy and precision to wet digestion and pneumatic nebulization An interlaboratory trial of a joint USEPA-AOAC method for ICP-MS determination of elements in a variety of waters was conducted. Mean recovery was - % and interlaboratory RSDs were -%. The method was adopted first action by AOAC International dissolution in concentrated HN,-HS.Semi- quantitative analysis using In as the internal standard was also performed. In-house RMs were prepared by incorporating the analyte elements into the polymer melt Single standard calibration was used following preparation by microwave oven-HNO digestion.The results of an inter-laboratory trial were reported. The foods were dried ashed at "C treated with HC the solution evaporated and the residue dissolved in. mol -' HN.The results for all the metals were good with the possible exception of Ni although the authors thought that no other method provided Ni results as good Cd Cr Cu Fe Ni Pb Zn Samples were decomposed using microwave Various RMs Various Water MS;ICP;S MS;ICP;L Various Food contact plastics MS;ICP;L Various RMs Various Foods MS;ICP;L AA;F;L AA;ETA;L MULTI-ELEMENT ANALYSIS Foods Various Lobster Free and bound Ag Cd Cu and Zn were measured in lobster digestive gland by extraction followed by gel permeation chromatography and final analysis by ETAAS Ag and FAAS Cd Cu Zn.The results were used to investigate processing of shellfish Bread type could be differentiated by PCA Al Ca Cu Fe K Mg Zn Two microwave methods were used for sample dissolution using either closed vessels with pressure relief valves or high pressure reactors. No differences were observed between the results for the two approaches Al Cu Fe Hg Pb Na Zn in Spanish For Cu and Pb wall atomization was used for Al Cr Cu and Fe a L'vov platform was required. The effect of metal contamination on oxidative stability was discussed A A;ETA; L AA;F;L Various Bread Various Canned tuna A A;ETA; L AA;F;L AE;F;L AA;CV;L Various Edible oils AA;ETA;L Journal of Analytical Atomic Spectrometry April Vol. R Element Matrix Sample treatment comments Reference Various Fruits and processed fruits AA;F;L A A;H y ;L nalytical methods for determining As Cu Pb Sn and Zn in compotes purees and jams were described in Polish 'The ASU Samples were heated to "C ground and a portion of the residue mixed with EtOH-H-NH,HP and diluted to ml.The suspension was ultrasonicated and stirred and p portions removed for analysis. The LODs for Cu Cr Fe Pb and Zn were and ng g-l respectively !Samples were charred dry ashed at °C for h wet with concentrated HNO and diluted to final volume with. mol -' HNO,.Standard additions gave recoveries between and % in Chinese ]Potentially toxic metals were determined in Balsamic vinegar. Mellowing gave increased concentrations and levels exceeded tolerances for wine and wine vinegar. However the levels consumed were below recommended dietary intakes HNO,-% H + and diluted to ml with H As Cd Cu Fe Mg Mn Pb Sn and Zn were determined in Jordanian dairy products in particular brined canned cheese. Packaging and contaminated raw materials lead to elevated levels Mushrooms were digested in YO HNO at "C in a pressure vessel Ca Fe K Mg Mn Na Zn in Chinese vegetables grown in a Saharan Wadi were determined and Cd and Pb unsurprisingly found to be at lower concentrations than in urban areas.The ASU A comprehensive review with references of the application of MS methods in studying trace element absorption and metabolism in humans Cu Fe Mn and Zn were determined in various soft fruits in the Gdansk region of Poland in Polish Cu Fe Mn and Zn were measured in varieties of apples from the Gdansk region of Poland in Polish Cu Fe Mn and Zn were determined in beans nuts and seeds imported into Poland in Polish S'tatistically different concentrations of Ca K Mg Mn and Na were observed with time during the month ripening period of Manchego cheese.The effects of Pb contamination and complexing agents citrate C- EDTA on the uptake of the nutrients B Ca Cu Fe Mg Mn Ni and Zn were investigated Nigerian smoked fish was dried ground predigested overnight in HNO, open-vessel digested to dryness and the residue ashed in a °C mufie furnace for h. The health implications of the results were discussed Cd Co Cr Cu Fe Mn Pb Zn. The elemental content of asparagus perilla garlic and radish was measured in Chinese.The performance of different acid mixtures in closed vessel microwave and pressurized ashing techniques was investigated. The most reliable approach for determining Al Ca Cu Fe K Mg Na P and Zn was the closed vessel microwave in conjunction with HNO or HNO,-H,O +. The optimum conditions for determining Cd Cu Hg Mn Pb and Zn were studied. One species of mushroom was found to contain Cd concentrations up to. mg kg-' dry mass Elemental profiles were used for selecting superior types of Ginseng Freeze-dried food was digested with % Concentrations of Cd Cu Fe Mn Pb and Zn in IC Various Beverages foods Various Confectionery.-- AA;ETA;SI A A;ETA;L Various Food additives Various Balsamic vinegar AA;F;L Various Hospital food Various Dairy products MS;ICP;L AA;-;L Various Edible fungi Various Vegetables AA;F;L AA;F;L AE;F;L Various Beverages foods Various Foods Various Fruit Various Apples AA-;L AA;F;L AA;F;L AA;-;L Various Nuts Various Cheese AE;ICP;L Various Cucumber Various Fish Various Vegetables Various Foods AE;ICP;L AECP;L Various Blueberries mushrooms Various Ginseng.-_- AE;ICP;L R Journal of Analytical Atomic Spectrometry April Vol. Element Matrix Various Wild mushrooms AA;F;L AA;Hy:L Various Fruits AA;-;L MULTIELEMENT ANALYSIS Beverages VariousTea AA;ETA;L AA;F,air-C H ;L Various Beverages foods Various Wines Various Tea Various Chinese selenium tea Various Wine Various Water Various Milk Various Beverages foods Various Cows milk Various Coffee Various Milk Various Beverages foods Various Orange juice.__- Y MS;ICP;L AE;ICP;L AA;ETA;L AA;ETA;L AE;ICP;L AA;-;L MS;ICP;L MS;ICPL AE;ICP;L AA;F;L M S;ICP;L AEF;L AA;ETA;L Sample treatment comments very high levels of Cd and Hg in particular were observed. Concentrations of Cd and Hg of and mg kg - ' respectively were recorded Cd Cr Cu Fe Mn Ni Pb Zn in Czech In a survey of fruit samples from the Lublin region of Poland no concentrations exceeding recognized safe limits were reported Cu Fe Mn Ni Zn in Polish In a study of heavy metals in Czech mushrooms Samples were dried powdered and heated under reflux with ml of HN-HS + before final dilution to ml with H,O or extracted using a method that simulated typical Chinese tea preparation.The ASU REE and trace metals were measured in wines. Samples were prepared simply by f dilution with H,O and measurement against matrix- matched standards Fe Mg Mn and Zn were determined in tea infusions by HPLC-ICP-AE spectrometry A by ETAAS.The authors claimed it was possible to differentiate the metals into inorganic and organic species in Chinese wet-ashed using HNO,-H,O and autoclaved in a stepwise sequence at temperatures up to °C. Dry leaves contained Se up to. pg g-' in German wines were not found to be influenced by geographical location Ca Fe K Mg Na in Spanish An interlaboratory trial of a joint USEPA-AOAC method for ICP-MS determination of elements in a variety of waters was conducted. Mean recovery was -% and interlaboratory RSDs were -%. The method was adopted first action by AOAC International multi-element analyses of milk the method that gave the closest comparisons between observed and reference values used. g of sample digested in. ml of concentrated HNO on a "C hotplate for d Leaves of this unusual beverage were lyophilized Concentrations of the measured elements in Spanish In a study of experimental parameters affecting.The ASU Four out of elements measured in cows milk were used in a principal components model to identify two different kinds of cow feed Cd Cr Cu Fe Mn Mo Ni Pb Zn Trace metal profiles in green coffee were used to identify geographical origin Multivariate statistical analysis of elements present in milk was used to differentiate products on the basis of differences such as pasteurization and sterilization processes Ca Cu Fe K Mg Mn Na Zn In a duplicate diet study the intakes of healthy French men were found to be adequate for Fe and Mn but the levels of Cu Se and Zn were below those recommended by the US Food and Nutrition board. Se was determined by GC-MS added pulpwash and for identifying geographical origin were among the methods described in an outstanding review of the current status in analytical approaches for assessing orange juice authenticity Atomic spectrometry procedures for determining Reference Journal of Analytical Atomic Spectrometry April Vol. R Table continued Element Various Milk VariousTea Various Juices Various Water Various Cows milk Matrix Various Milk Various Grape juice wine Technique; atomization; Sample treatment comments AE;ICP;L AA;-;L AA;ETA;L AE;ICP;L AA;Hy;L AE;ICP;L AA;F;L AA;ETA;L AA;F;L AA;-;L A rapid method for determining Ca K Mg and Na at LODs of and yg - in skimmed and whole milk was described. Concentrated HNO ml was added to sample ml in a PTFE reactor the vessels closed and placed in a laboratory or domestic microwave oven where they were subjected to a step procedure A HN,-HC mixture in conjunction with an open focused microwave digester was used to prepare a wide range of tea samples. Perhaps the most significant result was that Japanese teas contained in excess of yg ml-' Al Ba Ca Cu Mg Mn and Zn A British Standard method for determining Ca K Mg and Na in fruit and vegetable juices was described.The sample was ashed the ash absorbed in ml of mol I-' HC and diluted to ml with H,O. For K and Na the samples were mixed with CsCl solution prior to analysis. The role of surfactant vesicles as mobile phases in the HPLC-AAS speciation of toxic metals was investigated. The separations were obtained using a CI reverse-phase column modified by passing along it the surfactant didodecylmethylammonium bromide in % MeOH As Hg Se Sn A detailed study of milk and dairy products provided evidence that the manufacturing process plays a key role in the distribution of elements in milk derived products S'easonal variations in Ca K Mg and Na present in cow ewe and goats milk were studied over a year period Elemental composition was statistically coupled to isotopic data obtained using isotope ratio MS and H-NMR to determine the geographical origin of the named products. The classification of the products into different Appellations using discriminant analysis was performed with nearly % accuracy AE;-;L MULTI-ELEMENT ANALYSIS Miscellaneous Various Food contact plastics MS;ICP;L Samples were decomposed using microwave dissolution in concentrated HN,-H,SO,.Semi- quantitative analysis using In as internal standard was also performed. In house RMs were prepared by incorporating the analyte elements into the polymer melt Reference * Hy indicates hydride generation and S L G and S signify solid liquid gaseous or slurry sample introduction respectively. Other abbreviations are listed elsewhere. R Journal of Analytical Atomic Spectrometry April Vo. LOCATION OF REFERENCES. The full list of references cited in this Update have been published as follows

ISSN:0267-9477    

DOI:10.1039/JA996110103R

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

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COMPLIS laser spectroscopy experiment at ISOLDE.Proc. lnt. Symp. Capture Gamma-Ray Spectrosc. Relat. Top. 8th 1993. World Sci. Singapore Singapore 1994. 1001. 96/1798 Lhersonneau G. Enqvist T. Honkanen A. Huhta M. Jauho P. Jokinen A. Labtinen M. Lampinen A. Leino M. et al. Kern J. (Ed.) First results from the Jyvaskyla HI-cyclotron. Proc. Int. Syrnp. Capture Gamma-Ray Spectrosc. Relat. Top. 8th 1993. World Sci. Singapore Singapore 1994. 1004. 96/1799 Schuricht J. Depth resolving analysis of outdoor aerosol particles with secondary mass spectrometry. Wiss. Ber.-Forschungszent. Karlsruhe FZKA 5529 1995 113 pp. (Germany). Souzis A. E. Lareau T. T. Wittstruck R. Analysis of semi-insulating bulk GaAs using glow discharge mass spectrometry. Report ARL-TR-69; Order No. AD-A273032 1993 23 pp. (NTIS Springfield VA USA).Skowronski M. High resistivity buffer layers by oxygen doping. Report AFOSR-TR-94-0023; Order no. AD-A274986 1993 52 pp. (NTIS Springfield VA USA). Zou H. Hood G. M. Nakajima H. Roy J. A. Schultz R. J. Solid solubility of Ni and Co in a-Zr a secondary ion mass spectrometry study. At. Energy Can. Ltd. [Rep.] AECL AECL-11211 COG-94-541 1995 5 pp. 96/1800 96/1801 96/1802 Journal of Analytical Atomic Spectrometry April 1996 Vol. 1 1 203R5 Royal Society of Chemistry Analytical Division Atomic Spectroscopy Group Eighth Biennial National Atomic Spectroscopy Symposium The aim of this three day meeting is to promote and encourage developments in both fundamental and applied atomic spectroscopy including ICP-MS and XRF by providing a friendly environment where delegates can meet formally and informall:y to exchange ideas views and results.Plenary lectures given by world renowned spectroscopists' provide overviews of important areas of atomic spectroscopy. Invited and submitted lectures as well as posters cover the most recent developments in both pure and applied atomic spectroscopy. Although the majority of papers tend to focus on analytical applications presentations on theoretical studies or fundamental advances in AA AE AF and XRF are also important components of each BNASS. Social Programme l BNASS has an enviable reputation of being a friendly and dynamic meeting. A number of social 1 events including a Symposium Dinner will form an integral part of the meeting. Plenary Lecturers Dr S J Hill (University of Plymouth UK) Professor N Furuta (Chuo University Japan) Professor F C Adams (University of Antwerp Belgium) Professor J M Mermet (Universitk Claude Bernard- Lyon 1 France) and Professor G Hieftje (Indiana University Bloomington IN USA) Invited Lecturers Dr 0 Donard (UniversitC de Bordeaux 1 France) Dr S J Parry (CAFE Imperial College of Science Technology and Medicine UK) Dr S Fairweather-Tait (Institute of Food Research Norwich UK) Dr A T Ellis (Oxford Analytical Instruments Abingdon UK) Dr A G Howard (University of Southampton UK) Dr I B Brenner (Varian Ginzton Research Centre Palo Alto CA USA) Dr J Marshall (ICI Wilton UK) Dr N J Miller-Ihli (USDA Beltsville Agricultural Centre MD USA) Dr S D Tanner (SCEX Toronto Ontario Canada) and Professor D Littlejohn (University of Strathclyde UK).Call for Papers Contributed oral and poster presentations on recent developments in both pure and applied atomic spectroscopy - analytical applications theoretical studies or fundamental advances in AAS AES AFS inorganic MS and XRF.Three copies of abstracts must be submitted before 28 February 1996. Authors will be informed by 31 March 1996 of the acceptance or rejection of submitted papers and whether presentation will be by lecture or poster. Manuscripts of accepted papers will be considered for publication following the usual peer review process in a special issue (March 1997) of the Journal of Analytical Atomic Spectrometry (JAAS). Workshop Immediately prior to the 8th BNASS there will be a Short Course on Sample Pre-treatment and Sample Introduction for Atomic Spectroscopy 17 July a.m. 1996. Further Details Ms Brenda Holliday Royal Society of Chemistry Thomas Graham House Science Park Milton Road Cambridge CB4 4WF UK.Tel 4 4 (0)1223 420066; Fax +44 (0)1223 420247; E-maiI JAAS @RSC.ORG

ISSN:0267-9477    

DOI:10.1039/JA996110187R

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Validation of the Calibration Procedure in Atomic Absorption Spectrometric Methods Journal of Analytical Atomic Spectrometry W. PENNINCKX C. HARTMANN D. L. MASSART AND J. SMEYERS-VERBEKE ChemoAC Pharmaceutical Institute Vrije Universiteit Brussel Laarbeeklaan 103 1090 Brussels Belgium A general strategy for the validation of the calibration procedure in AAS was developed. In order to accomplish this the suitability of different experimental designs and statistical tests to trace outliers to examine the behaviour of the variance and to detect a lack-of-fit was evaluated. Parametric as well as randomization tests were considered. For these investigations simulated data were used which are based on real measurements. The results obtained indicate that to validate a straight-line model the measurement points should preferably be distributed over three or four concentration levels.In order to check the goodness-of-fit the significance of the quadratic term should be investigated. A lack-of-fit to a second degree model is better detected when the measurement points are distributed over more than four concentration levels. For an unweighted second degree model an analysis of variance (ANOVA) lack-of-fit can be used while a randomization test is proposed for a weighted model. A one- tailed Rest or an alternative randomization test should be used to trace a non-constant variance. Keywords Method validation; calibration; randomization test Method validation is the process of demonstrating the ability of a newly developed method to produce reliable results.' Generally one starts this process by validating the applied calibration procedure.The calibration model is used to describe the relationship between the analytical signal ( y ) and the concentration (x). One can assume for example that the Lambert-Beer law is valid within the applied concentration range so that a straight-line model (y=b,+b,x) can be used. However if the Lambert-Beer law is not valid and the straight- line model is fitted to the data the calibration procedure introduces a systematic error in the analysis results. The calibration method has to be evaluated prior to its routine use since the limited number of data points used routinely does not permit such an evaluation. Different approaches can be followed to validate the calibration procedure. A number of guidelines to validate the calibration function are for example published by the International Organisation for Standardisation ( ISO).273 However some important problems such as the investigation of the lack-of-fit of a weighted and a second degree calibration line are not discussed by ISO. Therefore in this paper a more general strategy for the validation of AAS calibration pro- cedures is given.This work investigates the validation of straight-line models ( y = b + blx) and second degree models ( y = bo + blx + b,x2) which are the most applied in practice and are included in the IS0 guideline^.^,^ Other calibration models are reported in the literature. Some workers4 use for example a cubic model ( y = b + blx + b,x2 + b3x3).However such a model has little physi- cal meaning and requires a large number of calibration stan- dards during routine analysis. Barnett' has described the calibration model that is included in the Perkin-Elmer atomic absorption spectrometers. Other models have been reported by Phillips and Eyring6 and Ko~cielniak.~ Since these models are not generally applied their validation is not discussed further here. The validation of the calibration procedure involves an examination of the behaviour of the variance and of the goodness-of-fit of the selected model. In order to accomplish this aqueous standards are measured at different concentration levels covering the complete calibration range. IS0,233 for example recommends to distribute ten standards uniformly over the calibration range and to perform ten replicate analyses of each of the lowest and highest concentrations. The exper- imental design is important since it influences the probability that a problem such as a lack-of-fit or a non-constant variance is detected. Therefore this work evaluates the applicability of different experimental designs. After the performance of the experiments one should first evaluate the data graphically.Often this permits an easy detection of important problems. A good way to do this is by examining the residuals.' Since this is not included in the IS0293 recommendations it is discussed briefly in this paper. For a statistical evaluation of the results one should check whether the data are free of outliers. Outlying points may disturb the normality of the data which is required by most of the tests used to examine the behaviour of the variance and the goodness-of-fit.Moreover the occurrence of multiple out- liers would indicate a fundamental problem with the method. In this paper two tests to trace single outliers namely the Dixon' and the Grubbs" tests and a test to trace paired outliers," are studied. Next the behaviour of the variance is investigated. This work evaluates the suitability of tests which compare variances at different concentration levels such as the F,2,3 Cochran,12 Hartley12 and Bartlettl3 tests as well as alternatives for these tests where the standard deviations at the different levels are estimated by the range.I4 Finally in order to trace a lack-of-fit the applicability of an analysis of variance (ANOVA) procedure15 and the significance of the quadratic terrnI6 are evaluated.An alternative test is considered for weighted m0de1s.l~ This work also investigates the suit- ability of a number of randomization tests." In that case the computed test statistic is not compared with a critical value but with a distribution which is obtained by random assign- ment of the experimental data. By deriving the distribution from the data themselves these tests should be less sensitive to deviations from normality.18 The different tests and experimental designs are evaluated in a systematic way by means of simulations which are based on a number of real data sets. The results of this evaluation are used to construct a general validation strategy for the calibration procedure in AAS.This could form the basis for a more general strategy applicable to other measurement techniques. EXPERIMENTAL The symbols that are used throughout this paper are summar- ized in Table 1. Journal of Analytical Atomic Spectrometry April 1996 Vol. 11 (237-246) 237Table 1 Symbols that are used ~ Total number of measurements N Concentration levels 1; ...; i; ...; n Number of replicates m,; ...; mi; ...; m xi=concentration at level i (i=l ... n) yij=jth absorbance measured at level i ( j = 1 . . . mi) Yi =mean absorbance at level i si = the standard deviation of the absorbances of level i wi = the range of the absorbances of level i b ; bl ; bz = the estimated calibration parameters j i = estimated absorbance at level i = b + b X j for a straight-line model = b + b,xi + b,x? for a second degree model eij = yij - ji =jth residual at level i Ci=mean of the residuals at level i Z =mean of all residuals ewij = ,h%K [ y z j - ji] =jth weighted residual at level i q= ,=the weight at level i - 1 3 Instrumental All programming was performed on a Compaq ProLinea 4/25s personal computer.Visual Basic 3.0 (Microsoft) was used as the programming environment. A Perkin-Elmer (Norwalk CT USA) Zeeman 3030 atomic absorption spectrometer equipped with an HGA-600 graphite furnace an AS-60 autosampler and a PR-100 printer were used for ETAAS determinations. For flame AAS determinations a Perkin-Elmer 373 spectrometer with a PRS-10 printer sequencer were used. Planning of Simulations Description of experimental data In order to simulate the data as realistically as possible some real experimental results were obtained first.The investigated data sets contain absorbances measured in aqueous solutions at different levels and over a large concentration range. Zn Fe and Cu measurements were obtained with flame AAS while ETAAS was used for Pb Cd and Mn measurements. For the different data sets the standard deviation is constant at low concentration levels but from a certain level it increases with the absorbance. This is illustrated in Fig. 1 for Fe measure- ments obtained with flame AAS. For the given example it is clear that from a certain concentration level the standard deviation increases linearly with the absorbance but this could T 0.008 } ,- I T 0.006 \ w v) t I 0.004 t A --.- rn ’ i- -+-+ t-+ Fe concentration/mg I-’ I .0.002 0 2 4 6 8 10 12 14 16 18 20 Fig. 1 the Fe concentration (data obtained with flame AAS) Standard deviation of the absorbance (n = 6 ) as a function of 1.2 1 .o 0.8 ‘ct 0.6 0.4 0.2 0 1 2 4 6 8 10 12 14 16 -0.2 Zn concentration/mg I-’ Fig. 2 Absorbances as a function of the Zn concentration (data obtained with flame AAS). The line represents the weighted second degree function that is computed from these data not be shown for all examined cases. The concentration level where the behaviour of the variance changes can be situated above below or within the selected calibration range. This must be investigated during the validation because the first situation (constant variance) permits the use of an unweighted model while for the other two (non-constant variance) the most precise results are obtained with a weighted model.Generally up to a certain concentration a straight-line model can be used to describe the relationship between concen- tration and absorbance. For higher concentrations a second degree calibration model is needed. This is also the case for the inspected data sets. Moreover it is difficult to build a good calibration model in a concentration range where the cali- bration line is partially straight (lower part of the range) and partially curved (upper part of the range). Fig. 2 shows for example the absorbance values measured with flame AAS as a function of the Zn concentration. It can be seen that the weighted second degree model that is computed from the data does not describe the measurement results accurately.In such a situation the calibration range should be split into two parts. For the given example an unweighted straight-line model can be used for concentrations up to 2mgl-’ while a weighted second degree model has to be used in the range between 2 and 15 mg 1-’ (results not shown). Consequently in the selected calibration range three situations can occur. The calibration line can be straight or curved over the complete range or it can be partially straight and partially curved. Moreover it is found that in the region where a straight-line model can be used the variance remains constant while it increases when the calibration line starts to bend. Simulations In order to evaluate the different statistical tests and experimen- tal designs for each situation considered 100 data sets were simulated.Randomized normal distributed numbers were gen- lerated in Visual Basic using the method proposed by Box and Mu1ler.l’ The suitability of the random generator was con- firmed by simulating a large number of data of which the normality of the distribution was checked graphically (with a ]histogram) as well as statistically (with a x2 test). Moreover in0 correlation was observed between data that were success- ively simulated. The simulations are based on the Pb data that were obtained by ETAAS. The applied parameters are given in Table 2. The calibration range (0-100 pg I-’) is divided into two equal parts in which different conditions can be valid. For example a data set can be simulated with a constant standard deviation in the lower part but an increasing standard deviation in the upper part of the calibration range.Similarly a first degree model can be valid in the lower part but not in the upper part. For 238 Journal of Analytical Atomic Spectrometry April 1996 Vol. 11Table 2 Parameters applied for the simulation of the data I . I . . . 0 - - ~ 0.05 0.10 a.15 0.50 0.25 0.30. 0.35 Experimental conditions- Concentration range Equation calibration line b1 = 0.003 0-100 pg I-' (divided into two equal parts) y =Po + plxi + & x i 2 with Po = 0.02 pz= -4.0 x -3.8 x ... -0.2 x 0.0 x Standard deviation homoscedastic oi = 0.002 heteroscedastic oi = 0.002 + yi 0.02 y i j ' = y i j + k a with k=4 6 8 10 or 12 Introduction outlier In case of a problem at the lowest concentration level (see Section 4) Y l j ' = ~ 1 j + c 0.010 0.005 Experimental design- Number of concentration Design levels (n) ( d ) -~ c11 c21 c31 c41 1151 0 .3 4 6 9 12 . m .. . 0.05 0.10 0.15 0.20 ,0.25 0.30 rn Number of replicates at each level (mi) 12 9 6 4 3 each investigation (evaluation of outlier tests tests to trace heteroscedasticity and goodness-of-fit tests) different simu- lations were performed which are specified further. Five different ways to distribute 36 measurement points symmetrically over the calibration range are considered (see Table 2). Design 1 for example positions 12 measurements at three concentration levels namely 0 50 and 100 pg 1-'. The choice of 36 points is arbitrary.The main reason why this number was selected is that it permits the residual variance to be estimated with a large number of degrees of freedom (> 30) and the measurement points can be distributed evenly over three or four concentration levels. These are the minimum number of levels to investigate a lack-of-fit to a straight line and second degree model respectively (see below). 0.006 0.004 0.002 0 -0.002 -0.004 . m . . . m . 1 . I ! . 0.05 ' 0.10 0.15 O.;O 0.2 0.30 ; 0.35 . ' m . I - v) -0.006 a ' 0.008 1 3 I 0.004 I ! I 1 . . -0.008 I The design that is proposed by IS0,293 namely ten replicates at both extremes and a single measurement point at the eight other concentration levels is not considered mainly for practi- cal reasons. In the first place this design cannot be applied for the validation of a weighted model.In order to determine the weight factors the variance must be estimated at the different concentration levels which requires the performance of repli- cate measurements. The lack of replicates also hampers the application of outlier tests at the different levels as well as the evaluation of tests which compare variance estimates at differ- ent levels such as the Cochran test. Moreover if one does not take into account the replicates at the extremes of the cali- bration range for the investigation of the goodness-of-fit as is proposed by KO several tests that are evaluated here (e.g. ANOVA lack-of-fit) cannot be performed. RESULTS AND DISCUSSION 1. Examination of the Residuals The residuals (eij) as given in Table 1 are the differences between the responses actually measured (yij) and those pre- dicted by the calibration model ( j i ) .In order to examine the residuals they are plotted against the predicted value. When a weighted model is used the weighted residuals (see Table 1) are plotted against the predicted value. Fig. 3 illustrates four situations that can occur. In the first situation [Fig. 3(a)] the residuals form a horizontal band which indicates no abnor- mality. In the second situation [Fig. 3(b)] the spread of the residuals increases with the size of the predicted value (and thus also with the concentration) which indicates that the variance is not constant. In such a situation the use of a weighted calibration model should be considered. Fig.3 (c) shows a trend in the residuals which indicates that the model is inadequate. Fig. 3(d) illustrates the residual plot in a situation where the calibration set contains an outlier. Draper and Smith' have shown that the estimated residuals are correlated but they indicate that this correlation does not invalidate the residual plot when N is large compared with the number of regression parameters estimated. 0.008 i ( b ) 0.004 1 . . = I m I -0.004 -0.008 . . rn ' I . . I ! 8 rn I I . . ' 0.05 '0.10 :0.15 0.25~ 0.301 0.35 = 0.20 -0.005 1 -0.01 0 I Predicted value Fig. 3 The residuals (Le. the difference between the measured and estimated absorbances) are plotted against the estimated absorbance to detect a calibration problem. The following plots can be obtained which indicate (a) no abnormality; (b) a variance that increases with the estimated absorbance (i.e.heteroscedasticity); (c) a lack-of-fit; and (d) an outlier Journal of Analytical Atomic Spectrometry April 1996 Vol. 1 1 239Table 3 Test criteria to trace an outlier at concentration level i. The applied symbols are explained in Table 1 Test criteria for Dixon’s test as presented by ISO:5 When 2<m<8 When 7<m<13 Q= When 12<rn<41 Yi2-Yi1 and Q= Yim-Yi(m-1) Y i m - Y i 2 Yi(m - 1 ) - Y I Yi3-Yi1 and Q= Yim-Yi(m-2) Y i m - Y i 3 Q= Y i ( m - 2 ) - Y i l Test criteria for Grubbs single outlier test? and z= - Test criteria for Grubbs’ paired outlier test:7 z2= - with si’ the standard deviation of leaving out a pair of values Y i m - j i Y i l - P i z= __.Si Si 1 - s i t Si 2. Detection of Outliers 2.1. Description of tests After the performance of the experiments one inspects each of the concentration levels for outliers. This work considers the Dixon’ and the Grubbs tests’’ which are the most generally applied tests for the detection of a single outlier. The Dixon test is applied as originally presented in the I S 0 guidelines.’ The test criteria are given in Table 3. In contrast to the Dixon test which is based on a range the Grubbs or maximum normalized deviation (MND) test makes use of the standard deviation to detect outliers. The Grubbs test criterion is also given in Table 3. The use of the Grubbs test is recommended by the Association of Official Analytical Chemists (AOAC)” and is also preferred in the latest draft I S 0 document.21 Multiple outliers can be detected by repeated application of a test for single outliers.However paired outliers may mask each other so that neither of them is detected with a single outlier test. The Grubbs’ pair statistic for the detection of two outliers given in Table 3 investigates the decrease in the standard deviation when removing a pair of values. 2.2. Evaluation In order to evaluate the performance of the described tests samples containing 3- 18 normally distributed measurement points were simulated. Single outliers were introduced at 4 6 8 10 or 12 standard deviations (0) of the population mean. In order to introduce two paired outliers the first was positioned at 4 6 8 10 or 12 standard deviations while the second was put at two times the position of the first.For each situation 100 samples were simulated and the tests were performed at the 5% significance level. For all investigated situations with sample sizes larger than three similar results are obtained with both single outlier tests. Fig. 4 shows for example the percentage of positive test results when an outlier is positioned at 60 or when no outlier is present. The probability of correctly detecting an outlier decreases with a decreasing sample size. One can see that for sample sizes below six the probability of not detecting an outlier when it is present (p error) becomes very high. The probability of falsely detecting an outlier (a error) varies around 5% which is in agreement with the specified significance level.However for a sample size equal to three the number of false positive results (a error) obtained with the Grubbs test is -a - --_ _ _ i t - q--_ - - - - $ - 2 4 6 8 10 12 14 16 18 Sample size r 1 - 4 Fig.4 Percentage of positive test results obtained with the Grubbs (squares) and the Dixon (triangles) test when an outlier is positioned at 6s (solid line) and when no outlier is present (broken line) unexpectedly high. There is clearly a problem with the Grubbs test for very small sample sizes. For a data set that contains 2 outliers the Grubbs test performs better than the Dixon test. The best results are obtained with the test for the detection of paired outliers. For example with nine measurements of which one is at 40 and another at 80 a problem is detected in 21 53 and 81% of the cases with the Dixon test Grubbs test and the Grubbs test for paired outliers respectively.The probability of falsely detecting a problem (a error) with the paired outlier test varies around 5% (significance level) for samples containing 18 12 and 9 measurements. However for samples that contain only six measurements the a error is about 11 YO. These results indicate that to avoid difficulties with false outliers the number of replicate measurements at each concen- tration level should be sufficiently high (at least >4). When no significant outlier is detected with the single outlier test one should check the data set for two paired outliers that may mask each other. This test however requires even larger sample sizes (> 6). The Behaviour of the Variance 3.1.Description of the evaluated tests Parametric tests. I S 0 proposes to use a one-tailed F-test to check (a) whether the variance at the highest concentration level is significantly larger than at the lowest concentration level and (b) whether the variance at the lowest concen- tration level is significantly larger than at the highest con- centration l e ~ e l . ~ ? ~ For AAS applications only the first test is meaningful because one knows that the variance when not constant increases with the concentration. Other tests which can be applied to trace a non-constant variance use estimated variances at different levels. In this work the suitability of the Cochran,” Hartley12 and BartlettI3 tests is investigated. Table 4 shows how the test statistics are computed. Cochran compares the ratio between the highest variance and the sum of the variances with a critical value.Hartley on the other hand uses the ratio between the highest and the lowest variance. Theoretically both these tests for which specific tables exist require an equal number of measurement points at each concentration level. However I S 0 indicates that for the Cochran test small differences in the number of points can be ignored and applies the Cochran criterion for the number of measurements that occur at most concentration levels.’ The more complex Bartlett test does not assume an equal number of points at the different levels. A quantity M/C is computed I(see Table 4) which is distributed as x2 when the variances are not significantly different.All these tests (Cochran Hartley Bartlett and F-test) are based on the comparison of estimated variances (s2). Some workers14 propose to test the sample range (w). Correction terms are published14 by which the range 240 Journal of Analytical Atomic Spectrometry April 1996 Vol 11Table 4 Evaluated test parameters to detect a non-constant variance. The symbols are explained in Table 1 Smm2 r = ~ Smin' Hartley F-test Bartlett M/C with where vi = mi - 1 must be divided to obtain an estimation of s. These estimations can then be applied in parametric statistical tests such as the F-test. Alternatives for the Cochran and Hartley tests based on the ranges have also been described.14 The test statistics for these tests are also given in Table 4.Randomization test. Apart from the parametric tests which are generally applied this work also investigates the applica- bility of a randomization test" to trace heteroscedasticity. The randomization F-test that we propose is illustrated in Table 5. First at each concentration level the squared differences between the individual and the mean measurement results are computed (di;). Since the size of the d2 values depends on the variance at that level the test statistic for the experimental data (Re) is computed as the sum of the d2 values at the upper concentration level divided by the sum of the values at the lowest level. In a next step the d2 values are randomly permuted between the concentration levels and for each permutation an R value is computed. If the d2 value (and thus the variances) at the upper and the lower concentration levels are similar R values will be found that are distributed around Re.However if the d2 values at the upper concentration level are significantly larger most of the R values will be smaller than Re. Consequently the significance level can be computed as the ratio between the number of permutations with R,>R to the total number of permutations. In this work the test results are based on 1000 permutations obtained by means of a random data permutation program.18 3.2. Performance under normal conditions As already mentioned five different ways to distribute the 36 measurement points symmetrically over the calibration range were considered. Fig. 5 shows the number of positive test results for these designs in a situation where the variance is 1 h s? v Q) v) 0 .- .- .I- n \ 0 ' I I I I Design 1 Design 2 Design 3 Design 4 Design 5 Fig.5 Percentage of positive test results obtained with Cochran (A) Hartley (A) Bartlett (0) and F (H) tests in a heteroscedastic situation constant in the lower part of the calibration range but increases in the upper part. It can be seen that for all tests the best results are obtained with the design that positions all meas- urement points at three concentration levels (design 1). Distributing the measurements over more levels and thus reducing the number of replicates at each level decreases the probability of detecting the heteroscedasticity. When the different tests are compared one can conclude that the best results are obtained with the Bartlett and the F-tests.The F- test has its simplicity as an additional advantage. Moreover this test is recommended by IS0.273 For homoscedastic measurements the evaluated tests produce between 2 and 10% of false positive results which is in agreement with the specified significance level of 5%. For the tests that estimate the standard deviation by the range a similar performance is observed. The test that uses the ratio of the smallest to largest absorbance range for example performs similarly to the classical Hartley test. Moreover determining the significance level of the F-test by a randomization procedure gives similar results as using a criti- cal value. 3.3. Performance in the presence of outliers Since there is always a probability that an outlier is not detected it is important to examine the effect of such a measurement point on the applied tests.Here a number of situations are considered where an outlier at one of the concentration levels results in an overestimation of the variance at that level. With homoscedasticity this overestimated variance can lead to an increased number of false positive conclusions. Fig. 6 illustrates this in a situation where the lower or the upper concentration level contains an outlier at 60. With the Bartlett test for example between 50 and 80% of false positive results are obtained depending on the applied design. Similar results are obtained with the Cochran and Hartley tests (not shown). The F-test is only affected by the outliers at the extreme levels because it does not use the data of the other levels.Moreover since this test is one-sided an outlier at the lowest concen- tration level does not increase the number of false positive results (see Fig. 6). When the upper concentration level con- tains an outlier the F-test gives a comparable number of false positive results as the other tests. However for the most suitable designs (designs 1 2 and 3) this number largely decreases when the significance level of the test is determined by a randomization procedure (see Fig. 6). A similar conclusion is obtained for data sets where one of the concentration levels is contaminated with two outliers. The number of false positive results obtained with the F-test is only increased by outliers ::L*+ 0 Design 1 Design 2 Design 3 Design 4 Design 5 Fig.6 Percentage of positive test results obtained with the Bartlett test (squares) the F-test (triangles) and the randomization F-test (diamonds) in a homoscedastic situation but with an outlier (60) at the lower (solid line) or upper (broken line) concentration level Journal of Analytical Atomic Spectrometry April 1996 Vol. 11 241at the upper concentration levels while the other tests are also affected by an overestimation of the variance at the other levels. When in a heteroscedastic situation the variance at the lowest concentration level is overestimated owing to an outlier an increased number of false negative conclusions can be obtained. In that case the real difference between the variance at the highest and lowest concentration levels is underesti- mated so that an existing heteroscedasticity is masked.As an example a situation is considered where design 1 is applied and the real standard deviations at the lowest the middle and the upper level of the concentration range equal 0.002 0.002 and 0.008 respectively. The lowest level is contaminated with an outlier which leads to an overestimation of the variance at this level. With an outlier positioned at 40 or at 60 the probability to detect the heteroscedasticity with the F-test decreases from about 100 to 65 and 30% respectively. Determining the significance levels of the I;-test by a randomiz- ation procedlure does not improve the results. With the Bartlett test this decrease is also observed but the number of positive test results stabilizes and even slightly increases for important outliers.This is because in this situation the variance at the lowest level is overestimated in such a way that it becomes significantly larger than the variance at the other levels. This effect is not experienced with the one-tailed F-test which checks whether the variance at the upper level is significantly higher than at the lower level. 4. Goodness-of-fit for Homoscedastic Data 4.1. Descriplion of the tests Parametric tlests. IS02,3 recommends as a goodness-of-fit test to check whether the data are better fitted by a second degree model ( y = bo + blx + b,x2) than by a straight-line model ( y = b + blx) using an F-test. In this work we preferred to check whether b2 iis significantly different from zero using a t-test (see Table 6).When it is shown that the data are better fitted by a second degree than by a straight-line model one concludes that the straight-line model does not fit the data accurately. This does however not prove that the second degree model fits the data correctly as is illustrated in Fig. 2. ANOVA lack- of-fit’’ is a test which can be applied to check the goodness- of-fit of a model such as a straight-line or second degree model. The test which is described in Table 6 compares the error due to lack-of-fit with the pure experimental error. Randomization tests. Van der VoetZ2 has proposed a randomiz- ation test to compare the predictive accuracy of two calibration models. In this work we applied this test to check whether better predictions are made by a second degree model than by a straight-line model.Consequently it can be considered as a Table 5 Procedure of the randomization F-test 1. Computation of d2 values 2. Test param,eter for experimental data 3. Permutations The following steps are repeatedly performed 3.1. The d2 values are randomly permuted between the 3.2. The test parameter is computed for each permutation R concentration levels 4. Determination of signijicance level ’= =umber of permutations number of‘ permutations with R > Re Table 6 Parameters applied to detect a lack-of-fit of an unweighted calibration model. The symbols are explained in Table 1 ANOVA lack-of-@ test Degrees of Mean squares Sum of squares (SS) freedom (df) (MS) N - n ss dfpe Lack of fit n-k SSlOf i = l dhof mi c ~ i - j i 1 2 with k = 2 for a straight-line model k = 3 for a second degree model MSlof MSF - F(iV -n),(n-k),a - Signijicance of second degree term randomization alternative of the parametric test proposed by IS0.293 The test compares the squared residuals for the straight- line model (ei?l) and the squared residuals for the second degree model (eij22).If both models have the same predictive ability ei:l and e i t 2 have equal distributions (HO = null hypothesis). However if better predictions are obtained with the second degree model the eij21 values are generally larger than the eij22 values. In order to test this the difference between the squared residuals dsij= eij21 - eij22 is computed for each measurement point. The mean of these values which is called T is then used as the test parameter.This value is first computed for the experimental data (T,). If both models have the same predictive ability the dsij values are small and distributed around zero so that T will be almost zero. However if the second degree model provides better estimations the dsij values will generally be positive so that a T value larger than zero is obtained. In the randomization test at each iteration random signs are then attached to the dsij values and the T value is computed (T,). If the original dsij values are distributed around zero (HO true) this operation has little effect on T so that T values are obtained which are sometimes larger and sometimes smaller than T,. However if random signs are attached to ds values that are predominantly positive (HO not true) most T values will be smaller than T,.Therefore the significance level is then computed as the ratio between the number of iterations with T,> T and the total number of iterations. In this paper we propose another randomization test to trace a lack-of-fit. This test investigates whether the prediction error estimated by the residuals is independent of the concen- tration level. As shown in Fig. 3(c) a lack-of-fit can be detected by demonstrating that the size of the residuals depends on the level where they are measured. Table 7 explains how this can be used in a randomization test. The numerator of the applied test parameter is an estimate of the variation of the mean residuals between the different concentration levels while the denominator estimates the variation within the levels.First the parameter value is computed for the experimental data (LJ. Then data permutations are performed. At each step the residuals are re-assigned to the different concentration levels and the test parameter is re-calculated (I+). Re-assigning the data has little effect on the test parameter when the residuals are randomly distributed over the concentration levels [see Fig. 3 (a)]. Consequently for the different permutations one will find test values which are sometimes larger and sometimes smaller than that obtained for the experimental data. However when the size of the residuals depends on the concentration level [see Fig. 3(c)] re-assigning the data will affect the test parameter. In fact for most permutations a test value will be 242 Journal of Analytical Atomic Spectrometry April 1996 Vol.11Table7 Procedure of the randomization test to investigate the goodness-of-fit 1. The test parameter m i [ ~ i - ~ z 2. Computation of the test parameter for the experimental data 100 80 60 40 20 0 W .I -20 -1 5 -1 0 -5 0 c. The residuals [el I ; . . .; eij; . . .; enm] are used to compute L .- 3. Permutations The following steps are repeatedly performed 3.1. The residuals are randomly assigned to the n concentration 3.2. The test parameter is computed for the ith permutation L levels 4. Determination of signi,ficance level ’= total number of permutations number of permutations with L > L found which is lower than that obtained for the experimental data. The significance level is then calculated as the ratio between the number of permutations with a test parameter higher than that computed with the experimental data (L,.> L,) and the total number of permutations. In this work the test results are again based on 1000 random permutations. Strictly speaking the proposed test as with most statistical tests is applicable only when the data are independent. For the estimated residuals this is not the case owing to the correlation that exists between them.’ However when the number of measurement points is large compared with the number of regression parameters estimated the effect is small,’ so that it can be ignored. 4.2. Performance under normal conditions First the validation of a straight-line model is investigated. For the test that is based on the significance of the quadratic term the best result is theoretically found with design 1.It follows from the D-optimality principle23 that the volume of the confidence region for the calibration parameters of a second degree polynomial is minimized when the measure- ments are equally distributed over the two extremes and the middle of the concentration range. It is clear that the more precisely the calibration parameters are estimated the easier it is to demonstrate that the quadratic term is significantly different from zero. For the ANOVA lack-of-fit it is more difficult to explain theoretically which is the optimum design. The simulations show however that the design that distributes all measurement points over three concentration levels (design 1 ) is the best to trace a lack-of-fit of the straight-line model with both tests.The sensitivity of the tests decreases when the number of concentration levels over which the measurements are distributed increases and the number of replicates at each level decreases. This is illustrated in Fig. 7(u) for the ANOVA lack-of-fit. One can see for example that for a calibration line with a quadratic term equal to - 12 x lop7 the lack-of-fit to the straight-line model is almost certainly detected when design 1 is used. With design 5 on the other hand the probability of correctly detecting the lack-of-fit is about 30%. The test based on the significance of the quadratic term is less affected by the applied design [see Fig. 7(b)]. Compared with the ANOVA lack-of-fit this test gives similar results when the most suitable design is applied but better results when the other designs are applied.The randomization tests give less good results. For example ANOVA lack-of-fit detects a problem in 97 88 and 34% of the cases when the 100 80 60 40 20 0 -20 -15 -1 0 -5 0 Quadratic term (x lo-’) Fig. 7 Percentage of cases for which (a) a lack-of-fit is detected with an ANOVA and (b) a significance of the quadratic term is detected for a curved calibration line and for different designs. The lines correspond to H design 1; 0 design 2; + design 3; 0 design 4; and A design 5 calibration lines contain a quadratic term equal to - 12 x -8 x and -4 x respectively (design 1 applied). With the randomization test described in Table 7 this is in 93 72 and 18% of the cases.The randomization test proposed by van der Voet22 detects a lack-of-fit in 82 56 and 13% of the cases. The number of false positive conclusions obtained with the randomization tests is situated between 2 and 6% which is in agreement with the specified significance level of 5%. Similar conclusions are obtained for situations where the lack-of-fit to the straight-line model is the result of problems other than a curvature to the x-axis. For example a situation is considered where data following a straight-line model are simulated and a constant value cb is added to all measurement points of the lowest concentration level. Also in that situation the test based on the significance of the quadratic term and the ANOVA lack-of-fit give the best results and they should preferably be combined with design 1.In order to validate a second degree model an ANOVA lack-of-fit is applied. Design 1 which uses only three concen- tration levels cannot be applied here. Table 6 illustrates that with three parameters to estimate ( k = 3 ) and three concen- tration levels (n=3) the degrees of freedom of the error due to lack-of-fit would be zero. In order to simulate a lack-of-fit to a second degree calibration model curved calibration lines were simulated and a constant value (cb) was added to the measurement results of the lowest concentration level. Fig. 8 gives the number of positive test results for the different cb values added and for different designs. For the given situations the most suitable designs to detect a lack-of-fit are designs 3 and 4.For example when cb=0.005 with design 2 a lack-of- fit is detected in 30% of the cases while designs 3 and 4 detect it in about 50% of the cases. Thus in contrast to the straight- line model the distribution of the measurement points over the minimum number of concentration levels (four in this situation) does not guarantee the best results. The reason for this is explained further for the weighted second degree model where this problem is even more important. The randomization test gives less good results than the ANOVA lack-of-fit. For example for cb values of 0.002,0.004 and 0.006 a lack-of-fit is detected in 16 33 and 62% of the cases respectively when Journal of Analytical Atomic Spectrometry April 1996 VoL 11 243'OiI 60 A 501- 4-== ' Design 2 Deskn 3 Des'ign 4 Deiign 5 ' 1 Fig.8 Percentage of positive test results obtained with an ANOVA lack-of-fit for a second degree model in a situation where the lowest concentration level is contaminated. To simulate this problem constant values (cb) of 0.00 (H) 0.02 (0) 0.03 (+ ) 0.04 (0 ) 0.05 (A) and 0.06 ( A ) were added to the absorbances of the lowest concentration level ANOVA lack-of-fit and design 3 are applied. With the same design the randomization test detects a lack-of-fit in 4 16 and 42% of the cases respectively. 4.3. Performance in the presence of outliers The effect of outliers is only evaluated for the validation of a straight-line model. Two outlier problems are examined namely a curvature that is masked by one or two too high measurement results at the upper concentration level and a curvature that is falsely detected owing to one or two too high measurements at the middle concentration level.For the most suitable design (design 1) the effect of an outlier at the upper level is the same for the ANOVA lack-of-fit and the test based on the significance of the quadratic term. When the curvature is strong and the outlier is not very large the probability of detecting a lack-of-fit to the straight-line model is little affected. However when the curvature is weak and the outlier is important the probability of detecting the curvature decreases. For example when the quadratic term equals - 12 x -8 x lop7 and -4 x a lack-of-fit is detected in 97 95 and 34% of the cases respectively.When an outlier (60) is introduced at the upper concentration level the probabilities decrease to 89 28 and 3%. With two outliers at the upper concentration level (40 and 80) the probabilities to detect the lack-of-fit are 25 3 and 1%. In a similar way to what was described above also in the presence of an outlier the signifi- cance of the quadratic term is less affected by the applied design. The probability of falsely detecting a curvature increases if the middle concentration level contains one or two outliers. With design 1 for example and a single outlier (60) at the middle concentration level one falsely detects a lack-of-fit to the straight-line model in 10% of the cases with the ANOVA lack-of-fit as well as with the test based on the significance of the quadratic term.When the middle concentration level is contaminated with two outliers (40 and 80) a lack-of-fit is detected in 22% of the cases. The tests are performed at a significance level of 5% so that a number of false positive results around this level is expected. In a similar way to what was described above also in the presence of outliers the randomization tests are less sensitive than the parametric tests. This means that the number of false positive results owing to an outlier in the middle of the concentration range is lower with the randomization tests. However the probability of correctly detecting a curvature when the upper concentration level contains an outlier is also lower with the randomization than with the parametric test.Therefore one cannot say that the randomization tests are more robust to outliers. 5. Goodness-of-fit for Heteroscedastic Data 5.1. Description of the tests In order to examine the goodness-of-fit of a weighted cali- bration model two parametric and two randomization tests are evaluated. The first testI7 computes the sum of squares S = c K(Ji-9i)2 where the weight factor is the inverse of the variance of yi. If the calibration model describes the data accurately the value of S has a x2 distribution with n-2 or n - 3 degrees of freedom for a straight-line and a second degree model respectively. As a second test to validate a straight- line model one can also check the significance of the quadratic term for a weighted model. The evaluated randomization tests are similar to those described in Section 4.1.In order to apply the test proposed by van der Voet22 for weighted models the weighted residuals pi ( yij-ji) are used. Thus one computes the mean difference between the squared weighted residual for the straight-line model and the squared weighted residual for the second degree model and applies the test on these values. For the test that is proposed by us (see Table 7) one states that the weighted residuals must be randomly distributed over the concentration levels. Thus the randomization test which is explained in Table 7 can also be applied on the weighted residuals. Here it is also assumed that the correlation that exists between the weighted residuals does not affect the test results. 5.2. Performance Fig. 9 compares the performance of the evaluated tests for the validation of a weighted straight-line model.A situation is considered where all measurement points are distributed over three concentration levels (design 1) and where the relative standard deviation equals 2%. It can be seen that the best results are obtained with the test that determines the signifi- cance of the quadratic term. Less good results are obtained with the randomization test that is proposed by us. The other tests seem less suitable. Regarding the selection of the design the same conclusions can be made as for the unweighted straight-line model namely that the best results are obtained with design 1. It should also be remarked that when the heteroscedasticity is not detected and the goodness-of-fit tests for an unweighted model are performed satisfactory results are still obtained when the data set is free of outliers.However when the middle concentration level is contaminated with two outliers (40 and 8 4 the probability of obtaining a false positive result with the unweighted test is very high (between 20 and 30%). The weighted tests on the other hand are little affected by these outliers. This is probably because the outliers increase 80 h $? - 60 a) .- U a 40 20 0 B I I -30 -25 -20 -15 -10 -5 0 Quadratic term (x Fig. 9 Percentage of cases where a lack-of-fit to a weighted straight- line model is detected with the x2 test (O) the randomization test proposed in Table 7 (A) the randomization test proposed by van der Voet (+ ) and by determining the significance of the quadratic term (H) 244 Journal of Analytical Atomic Spectrometry April 1996 Vol.11. . 0.5 0 - -1 -2 . . 0 -0.5 I 10 20 30. 40 50 60 '70 80 90 100 I ~ . I ' 10 20 -30 40 50 60 70 80. 99 rn ~. - 100 - . I m . . . . I . . . . . -41 Concentration Fig. 10 Weighted residuals for a second degree calibration model in a situation where a contamination of the lowest concentration level occurs. Design 2 (a) and design 5 (b) are applied. the variance at the middle concentration level so that a smaller weight is given to this level. In order to evaluate the goodness-of-fit of a weighted second degree model the randomization test described in Table 7 performed on the weighted residuals is found to be the most suitable test. The probability to detect a lack-of-fit increases when the measurement points are spread over an increasing number of concentration levels so that the best results are obtained with design 5.This is because for a small number of concentration levels an alternative model can be found which fits the actual data accurately but does not give a correct description of the relation between concentration and absorbance. This is illustrated in Fig. 10. The weighted residuals for a calibration line obtained with design 2 and design 5 are given in a situation where a curved line is simulated but a value cb is added to all data points of the lowest level. Design 5 clearly indicates a problem because the weighted residuals are not randomly distributed over the concentration levels. With design 2 on the other hand no problem is detected.However the calibration model that is found with this latter design cannot be used to make correct estimations. The x2 test performs less well than the randomiz- ation test. With design 4 for example and Cb=0.002 0.004 and 0.006 the randomization test detects a lack-of-fit in 24 58 and 90% of the cases respectively. With the x2 test the lack- of-fit is only detected in 1,16 and 38% of the cases respectively. In contrast to what is concluded for the straight-line model the goodness-of-fit tests that assume homoscedasticity fail when they are applied on a second degree model in a heterosc- edastic situation. Recommended Strategy The described results were used to build a strategy for the validation of atomic absorption calibration models.The pro- posed strategy is based on the assumption that the analyst has an idea of the linear range of the calibration line before he starts the validation. Consequently he will preferably try to demonstrate the suitability of a straight-line model within this range. However sometimes the linear range is so small that one is obliged to work in the curved concentration range. The analyst will then try to demonstrate the suitability of a second degree model within the specified calibration range. A number of experienced analysts whose opinion was asked stated that to ensure the general acceptance of the validation strategy it should be combined with information on how to continue when a problem such as a lack-of-fit is detected. Although this is not part of the validation the results of the validation experiments can be used to give these recommen- dations.In order to avoid confusion in this section a distinction is made between the real validation of the calibration line and a number of additional tests that are performed to advise the analyst on how to continue. Validation strategy In order to validate a straight-line model the analyst is advised to apply experimental design 2 (ie. nine replicates at four concentration levels). Design 1 (three concentration levels) is more sensitive but does not permit a further investigation when a lack-of-fit is detected. Designs 4 and 5 on the other hand do not permit an accurate outlier detection at the different concentration levels and are less suitable for the validation of a straight-line model.Moreover owing to the small number of replicates at each concentration level these designs are not really suitable to evaluate a possible het- eroscedasticity. For the validation of a second degree model an alternative design is proposed because none of the evaluated designs seems optimum. The designs that position all measurement points at a small number of concentration levels (designs 1 2 and 3) are the most appropriate to detect a heteroscedasticity but are the least suitable to detect a lack-of-fit especially for a weighted second degree model. The designs that spread the measurement points over a large number of levels (designs 4 and 5 ) on the other hand are the most suited to detect a lack-of-fit but the small number of replicates makes them scarcely appropriate to investigate the behaviour of the variance.Therefore it is proposed to position nine replicates at both extremes and six replicates at five other concentration levels equally spread over the concentration range. This design requires more measurement points than for that proposed for the validation of a straight-line model (48 instead of 36) but additional effort can be required for the validation of a more complex model. After the performance of the experiments the results should first be evaluated visually. The most appropriate way to do this is by plotting the residuals uersus the predicted value. The statistical evaluation of the experimental results for a straight- line model is summarized in Fig. 11. First single outliers are traced at the different concentration levels applying a Grubbs test. When no single outliers are found the presence of possible paired outliers is investigated.When in the complete data set no more than two outliers are detected the analyst can remove them and continue the evaluation of the data. More outliers indicate a fundamental problem with the analysis method which must be investigated. When the problem that is respon- sible for the outliers is solved a new data set should be prepared. The homoscedasticity of the data is then investigated. One investigates whether the variance at the highest concen- tration level is significantly larger than at the lowest concen- tration level. In order to accomplish this one can use a one- tailed F-test or the alternative randomization test which is even more suitable.Depending on the result an unweighted or a weighted model must be used. In order to investigate the goodness-of-fit of the straight- line model one checks whether the data are better fitted by a second degree model. If this is not the case one confirms the suitability of a straight-line model with an ANOVA lack-of-fit (for an unweighted model) or with a randomization test (for Journal of Analytical Atomic Spectrometry April 1996 Vol. 1 I 245method does not perfow as expected Straight line model is not suitable outliers from data F test n l y 171 Use unweighted 'rl U s e weighted n l Unueighted straight line model Weighted straight line model Fig. 11 Strategy for the evaluation of the experimental results a weighted model).These tests are also those used to demon- strate the suitability of a second degree model. Recommendations after the detection of a lack-of-t When the validation shows that calibration data cannot be described by a straight-line model two actions can be taken. First one can check whether a straight-line model can be valid over a smaller concentration range. Therefore the upper concentration level of the design is eliminated and the tests for the validation of a straight-line model are applied on the reduced calibration set. Possibly a decrease of the calibration range also allows the use of an unweighted instead of a weighted model. When no suitable straight-line model can be built one can investigate the suitability of a second degree model. It must be clear that those tests on a reduced calibration set are only applied to give an indication of how the analysis method can be adapted.They cannot be used as validation results. If these tests indicate for example that a straight-line calibration model seems suitable over a smaller concentration range than specified at the start of the validation the analyst can adapt his method and start the validation of this new method. REFERENCES 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Taylor J. K. Anal. Chem. 1983 55 600A. IS0 International Standard 8466- 1 Water Quality-Calibration and Evaluation of Analytical Methods and Estimation of Pevformance Characteristics-Part 1 Statistical Evaluation of the Linear Calibration Function International Organisation for Standardisation Geneva 1990. I S 0 International Standard 8466-2 Water Quality-Calibration and Evaluation of Analytical Methods and Estimation of Performance Characteristics-Part 2 Calibration Strategy for Non-linear Second Order Functions International Organisation for Standardisation Geneva 1990. Wendt R. H. At. Absorpt. Newsl. 1968 7 28. Barnett W. B. Spectrochim. Acta Part B 1984 39 829. Phillips G. R. and Eyring E. M. Anal. Chem. 1983 55 1134. Koscielniak P. Anal. Chim. Acta 1993 278 177. Draper N. and Smith H. Applied Regression Analysis Wiley New York 2nd edn. 1981. I S 0 International Standards 5725 International Organisation for Standardisation Geneva 1986. Grubbs F. E. and Beck G. Technometrics 1972 14 847. Kelly P. C. J. Assoc. 08. Anal. Chem. 1990 73 58. CETEMA Statistique Appliqu6e a 1 'Exploitation des Mesures Masson Paris 2nd edn. 1986. Snedecor G. W. and Cochran W. G. Statistical Methods The Iowa State University Press Ames 7th edn. 1982. Lang-Michaut C. Pratique des Tests Statistiques Dunod Paris 1990. Massart D. L. Vandeginste B. G. M. Deming S. N. Michotte Y. and Kaufman L. Chemometrics a Textbook Elsevier Amsterdam 1988. Garden J. S. Mitchel D. G. and Mills W. N. Anal. Chem. 1980 52 2310. Cooper B. E. Statistics for Experimentalists Pergamon Press Oxford 1969. Edgington E. S. Randomization Tests Marcel Dekker New York 1987. Box G. and Muller M. Ann. Math. Stat. 1958 29 610. AOAC Referee 1994 October p. 6. I S 0 DIS 5725-1 to 5725-3 (Draft versions) Accuracy (Trueness and Precision) of Measurement Methods and Results International Organisation for Standardisation Geneva 1990/1991. Van der Voet H. Chemometr. Intell. Lab. 1994 25 313. Atkinson A. C. Chemometr. Intell. Lab. 1995 28 35. Paper 5/07400B Received November 10 1995 Accepted December 13 1995 246 Journal of Analytical Atomic Spectrometry April 1996 VGl. 11

ISSN:0267-9477    

DOI:10.1039/JA9961100237

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Optical Emission Studies of the Mach Disc Extracted From an Inductively Coupled Plasma With an Echelle Spectrometer and Segmented-array Charge-coupled Detectors* Journal of Analytical Atomic Spectrometry SHEN LUAN,+ HO-MING PANG AND R. S . HOUKS Ames Laboratory-US Department of Energy Department of Chemistry Iowa State University Ames I A 5001 I USA An inductively coupled plasma (ICP) is extracted into a small quartz vacuum chamber through a sampling orifice in a water- cooled copper plate. Optical emission from the Mach disc region is measured with a new type of Cchelle spectrometer equipped with two segmented-array charge-coupled device detectors the Optima 3000 from Perkin-Elmer. This device provides high quantum efficiency throughout the ultraviolet- visible region as well as low dark current and readout noise.The spectral background emitted by the Mach disc is very low. Axial profiles of the optical emission of a range of atom and ion lines are measured. The effects of aerosol gas flow rate on the intensities of various lines are investigated. The relationship between the location of the Mach disc and the pressure in the expansion chamber is also studied. The analyte line intensities are enhanced at higher pressure. Keywords Inductively coupled plasma; supersonic jet; Mach disc; atomic emission spectrometry; simultaneous multi-element analysis Measurements of optical emission from the reduced-pressure plasma extracted from an atmospheric pressure inductively coupled plasma (ICP) were first demonstrated by Houk and Lim.' The analyte line intensities from the reduced-pressure plasma were weaker than those from the ICP by a factor of approximately 1000.However the spectral background emitted by the reduced-pressure plasma was so low that it was indis- tinguishable from the dark current of the photomultiplier used (0.3 nA in this case). In contrast a substantial background is seen from the ICP alone throughout the ultraviolet (UV)-visible region.2 In a second paper by Lim et aL3 some fundamental characteristics of the reduced-pressure plasma extracted from an ICP were described. Gas kinetic tempera- tures were measured in the Mach disc region of the extracted plasma from the widths of emission and fluorescence lines and from the intensities of various OH band components. These temperature values were in the range of 2200-2500K as expected if collisions in the Mach disc reheat the sampled gas to temperatures approximately half of those outside the sam- pler in the ICP.495 Several other workers have also studied reduced-pressure emission sources extracted from ICPs.Kawaguchi et aL6 measured the dependence of emission on spatial position and background pressure in the expansion chamber. Gray7 reported a qualitative photographic study of the supersonic jet and shock waves. The expansion shrank and the Mach disc and barrel shock emitted more strongly as background pressure increased. Borer and Hieftje*-" evaluated the performance of a microwave-boosted reduced-pressure plasma extracted from an atmospheric pressure ICP. The reduced-pressure plasma was viewed axially so that emission from the ICP outside the sampler was also collected in contrast to the perpendicular viewing discussed in ref.1. Shibata et a1.l' measured Ar I and HP emission lines from the supersonic jet to determine electron density and excitation temperature. Recently an echelle polychromator equipped with two seg- mented-array charge-coupled device detectors (SCD) has been designed for inductively coupled plasma atomic emission spec- trometry ( ICP-AES).12*'3 This device provides high quantum efficiency in the UV region low dark current low readout noise as well as simultaneous multi-element capabilities which are perfectly suited to a tandem emission source with a low spectral background. The present work reports the joint use of the Mach disc emission source extracted from an ICP with an echelle spectrometer equipped with SCDs.The general objectives are both to study the basic characteristics of the Mach disc and to investigate possible methods to intensify emission from it for analytical purposes. EXPERIMENTAL Extraction System A scale diagram of the ICP and extraction system is shown in Fig. 1. The ICP torch along with the 40 MHz free-running radiofrequency (r.f.) generator from the Perkin-Elmer Optima 3000 were used here. The outer tube of the torch was shortened by 10mm. The ICP was operated vertically. A cross-flow nebulizer and Scott-type double-pass spray chamber were used to introduce aqueous samples. Typical operating con- ditions are listed in Table 1. A circular sampling orifice was drilled in a copper sampling disc.Different orifice diameters ranging from 0.56 to 1.06 mm were tested in the present work. The sampling disc (B in Fig. 1) was made very thin (approximately 4 mm in thickness) because it was considered desirable to be able to collect optical radiation from as close to the sampling orifice as possible. Soft copper tubing with an outside diameter of 3.2 mm was silver- Table 1 Typical instrumental operating conditions _ _ _ _ _ _ _ ~ ~ ~ ~ ~ ~ ~ * Presented at the Twenty-First Annual Conference of the Federation of Analytical Chemistry and Spectroscopy Societies (FACSS) St. Louis Missouri USA October 2-7 1994. Present address Thermo Jarrell Ash Corporation 27 Forge Parkway Franklin MA 02038 USA. * To whom correspondence should be addressed.Component R.f. generator ICP torch Cross-flow nebulizer Operating conditions R.f. power 1100 W Plasma gas flow 15 1 min-' Intermediate gas flow 1.0 1 min-' Aerosol gas flow 1.000 1 min-' Liquid flow 1.0 ml min-' Journal of Analytical Atomic Spectrometry April 1996 Vol. 11 (247-252) 247H- 4 Fig. 1. ICP and extraction system A ICP torch load coil and bonnet; B copper sampling disc; C water cooling coil; D cylindrical quartz tube; E flat Viton gasket; F threaded retaining rod; G pumping port; and H optical baffles soldered to the edge of the disc for water cooling. A shallow cone was made on the ICP side of the disc to make it easier to centre the sampling orifice on the axial channel of the ICP. A quartz cylinder was used as the wall of the extraction chamber so that the extracted plasma could be measured optically in the UV region.Flat Viton gaskets (0.8 mm in thickness) and threaded retaining rods sealed the quartz cylin- der to the sampling disc and pumping flange. A rotary vacuum pump (Edwards E2M18 pumping speed of 5.7 1 s-l) was connected to the extraction system. A Convectron vacuum gauge (Granville-Phillips) was introduced into the vacuum line. The meter readings of the gauge which was factory- calibrated for nitrogen were converted into argon pressures by using the conversion curve supplied by the manufacturer. An in-line valve was also employed to control the pressure in the extraction chamber. The entire extraction system was attached to a vertically movable stand that was fixed on top of the ICP torch box.The sampling orifice was centered on the ICP and was positioned 15 mm above the top of the load coil. The ICP was ignited with the sampling disc in position. The sampling disc was grounded. No severe secondary discharge or pinch e f f e ~ t l ~ ~ ’ was observed outside the sampling orifice. The orifice did not erode or expand over a period of several months and Cu lines from the sampler were not observed. Spectrometer An echelle polychromator with an SCD detection ~ y s t e m l ~ ~ ~ was used to measure the optical emission from the extracted plasma. Care was taken to shield the strong radiation from the ICP by using baffles made of steel sheets. The baffles were treated chemically to achieve a dull-black finish to intercept reflected and scattered light.The ceramic purge extension along with the quartz window was removed to accommodate the extraction system in the sample compartment. The vertical viewing position (viewing height) and the horizontal viewing position were changed by computer-controlled movement of the first transfer mirror. The viewing height could be changed from the load coil to 30 mm above the load coil in 1 mm increments. However some astigmatism ( 5 mm)I2 was intro- duced in the vertical direction by the transfer optics. In other words a 5 mm high segment of the source was actually viewed by the spectrometer at each observation position. The hori- zontal viewing position could be adjusted from -10.0 to 10.0 mm in 0.4 mm increments. RESULTS AND DISCUSSION Physical Appearance and Structure of Extracted Plasma The physical appearance of the extracted plasma is depicted in Figs.1 and 2. The dark ‘zone of silence’ was clearly visible. The zone of silence was surrounded by a concentric barrel shock and terminated in a perpendicular shock wave called the Mach disc. These shock waves were characterized by faint bluish red emission. Downstream from these shocks a red afterglow continued for some distance.'^^,^ Location of the Mach Disc as a Function of the Background Pressure in the Extraction Chamber In a photographic study of the shock waves Gray7 showed that the shock envelope is more compact when the background pressure in the extraction chamber increases. Ashkenas and Sherman,16 in their supersonic molecular beam experiments demonstrated that the Mach disc forms at a distance XM from the orifice (Fig.2) given by the following equation where P is the background pressure in the extraction chamber Po is the source pressure (in this case; 1 Torr = 133.322 Pa) and D is the orifice diameter. The validity of eqn. ( 1 ) for high temperature partially ionized gases such as the ICP has been confirmed by Kawaguchi et aL6 In the present study the location of the onset of the Mach disc X (Fig. 2) is measured by a cathetometer which consists of a telescopic levelling apparatus that slides up and down on a perpendicular stand with a finely graduated scale. The resolution of the scale for the cathetometer used is 0.05 mm. A log-log plot of X,/D versus Po/P is shown in Fig. 3. Results of linear regression are also shown in Fig.3 with an R value or correlation coefficient of 0.998. The change in location of the Mach disc with varying background pressure conforms closely to that predicted from eqn. ( 1) obtained in supersonic molecular beam experiments.16 The rather small difference between the coefficient found in the present work and that from eqn. (1) (ie. 0.62 uersus 0.67) i s probably due to the difference between the pressure measured by the gauge and the true ambient pressure in the chamber. The range of the measured background pressure was fairly ____+I I- D Fig. 2. Mach disc formation at a distance XM from the orifice 248 Journal of Analytical Atomic Spectrometry April 1996 Vol. 1120 10 9 8 Q 7 $ 6 5 4 3 2 &ID = 0.62 (PdP1)0.498 50 60 70 80 90100 200 300 400 500 Pol Pl Fig.3.Location of the Mach disc as a function of the argon background pressure in the extraction chamber (PI). The orifice diameter (D) used here was 0.85mm and atmospheric pressure (Po) was 740.1 torr. Note the error bars for the X,/D values narrow in the present study (from 1.8 to 9.5 Torr). The shock envelope was very faint at lower pressure making the measure- ment of the exact location of the onset of the Mach disc very difficult. On the other hand at higher pressures the shock envelope became more compact and was eventually blocked by the thin sampling disc. Axial Emission Profiles Axial profiles of the optical emission of various atom (I) and ion (11) lines are shown in Fig. 4. In this study the viewing height was changed by computer control of the image transfer optics.In these profiles the horizontal coordinate is the distance from the orifice (instead of viewing height above the top of the load coil). The sampling orifice is 15mm above the top of the load coil. The orifice used here was of 0.56mm diameter,' and the argon pressure in the extraction chamber was 1.8 Torr while sampling the ICP. As can be seen from Fig. 4 the intensities in the 'zone of silence' are low. They increase drastically with increasing distance from the orifice and reach maxima at around 7mm from the orifice which corresponds to the location of the Mach disc. For neutral atom lines (I) the profiles level off or drop off slightly above the location of the Mach disc while for ion lines (11) the profiles drop off much more significantly.The difference between the profiles for atom (I) and ion (11) lines is more profound for Mg than for analogous lines from Ca or Sr. Effect of Aerosol Gas Flow Rate on Emission The dependence of analyte line intensity on aerosol gas flow rate is shown in Fig. 5. In the present study the viewing height was chosen to be 7 mm above the orifice (22 mm above top of the load coil). The neutral atom lines (I) peak at 1.4-1.6 1 min-l. However for ion lines (11) some interesting fea- tures appear. The intensities of the Mg I1 lines are maximum at 0.6-0.7 1 min-'. The profiles for Ca I1 lines are double- humped with one peak at 0.7-0.8 1 rnin-l and a second one at 1.6 1 min-l. For Sr I1 lines the maxima are at 1.6-1.7 1 rnin-' with another small hump at about 0.8 1 min-I.In principle the ionic emission from the Mach disc IM+,MD can be expressed by the following proportionality (2) - E*/kT IM+,MDanM+,MD exc,MD 2 0 I '.L 5 c i 0 2 4 6 8 10 12 14 16 400 Ca (11) 393.386 n m 200 Ca (I) 422.673 nrn 01 ' 1 ' ' 0 2 4 6 8 10 12 14 16 160 120 80 40 Sr (11) 407.771 nm / - S r (11) 4 2 1 552 nm _____ 60 ~~~~ Sr (I) 460 733 n m 15 -- 0 I / / 0 2 4 6 8 10 I2 14 16 Distance from orifice/mm Fig. 4. Axial profiles of the optical emission of various atom (I) and ion (11) lines. The orifice used was of 0.56 mm diameter. The back- ground pressure in the extraction chamber was 1.8 torr. The concen- trations of these elements were 50 pg ml-l where nM+,MD is the number density of M+ ions in the Mach disc E* is the excitation energy of M+ ions k is Boltzmann's constant and Texc,MD is the excitation temperature in the Mach disc.The terms nM+,MD and Texc,MD in eqn. (2) are proportional to the analogous quantities outside the sampler in the ICP n~ + M D ~ ~ M + ,ICP Texc,MDCCTexc,ICP (3) (4) Journal of Analytical Atomic Spectrometry April 2996 Vol. 12 249v 240 r -1 60 7- - 0 0 0 5 1.0 1 5 2 0 Ca (11) 393.366 nrn I 200 ,- I Ca (I) 422.673 n m L5G 1 600 Sr (11) 407 771 nm 300 50 I i \ I _____~ S r (1) 460.733 nrn 80 Aerosol gas flow rate/l min-’ Fig. 5. Dependence of analyte line intensity on aerosol gas flow rate. The orifice used was 0.56 mm diameter. The background pressure in the extraction chamber was 1.8 Torr. The concentrations of these elements were 50 pg ml-’ where nM+,ICP and Texc,Icp are the number density of M+ ions and excitation temperature of the ICP just outside of the sampling orifice.When the aerosol gas flow rate is set to 1.6 1 min-l the apex of the initial radiation zone17 formed by aspirating a solution of yttrium at 1000 pg ml-I is located 1-2 mm below the sampling orifice. This sampling position generally corre- sponds to the highest M+ signal in ICP mass spectrometry (ICP-MS),’~ thus the highest value of ~zM+,Icp (hence nM+,MD) is obtained here. This ion number density factor is most important when a relatively small orifice (0.56 mm diameter in this case) is used because only the centre part of the axial channel is sampled. However at a lower aerosol gas flow rate (0.7 1 min-I) the sampling position is in the middle of the normal analytical zone,17 which is the region where Texc,Icp (hence Texc,MD) is highest.Thus the variation of ion line intensity with aerosol gas flow rate is caused by a competition between the nM+,MD factor and the Boltzmann factor in eqn. (2). For high E* lines (such as Mg I1 279.553 nm and Mg I1 280.270 nm) the Boltzmann factor is more important. Therefore Mg I1 emission is a maximum at a lower aerosol gas flow rate. For low E* lines (such as Sr I1 407.771 nm and Sr I1 421.552 nm) the nM+,MD factor is more important so they peak at a higher aerosol gas flow rate. The double emission humps for Ca I1 393.366 nm and Ca I1 396.847 nm indicate that the spatial changes in the ion number density factor and Boltzmann factor are of similar magnitude in this case. Effects of Background Pressure and Orifice Diameter With the orifice diameter of 0.56 mm and background pressure in the extraction chamber of 1.8 Torr the spectral background emitted by the Mach disc is very low usually less than 0.1 counts s-’ for a 200 s integration time.However it is obvious that the analyte intensities from the Mach disc need to be enhanced. One simple way to boost the analyte intensities from the Mach disc is to increase the background pressure in the extraction ~ h a m b e r . ~ ’ ~ Considering eqn. ( 1 ) when P increases X becomes shorter. If the Mach disc is too close to the orifice optical emission from the Mach disk will be difficult to measure simply because it will be blocked by the sampling disc. Considering eqn. ( 1 ) more closely if D increases X becomes longer.In the present study the orifice diameter was then enlarged to 1.06 mm and the background pressure was increased to 9.5 Torr. At a background pressure of 9.5 Torr the flow pattern downstream of the Mach disc is different from the case of 1.8 Torr as shown in Fig. 6. With higher background pressure the reflected shock forms a second barrel and another disc. Increasing the background pressure even further the pattern is repeated along the axis many times. As many as five successive patterns are observed with background pressure around 20Torr. Similar observations have been made by Gray.7 Axial profiles of the optical emission of various atom (I) and ion (11) lines with a background pressure of 9.5 Torr and orifice diameter of 1.06 mm are shown in Fig.7. In general the analyte line intensities are enhanced by using a higher PI = 1.8 torr P = 9.5 torr D = 0.56 mm D = 1.06 mm Fig.6. Dependence of the structure of the extracted plasma on background pressure and orifice diameter 250 Journal of Analytical Atomic Spectrometry April 1996 Vol. 112400 1 1600 M g (11) 279.553 nrn ::"L 600 Mg (11) 279 553 nm +p*\\J 1200 1 800 1 I 800 I GO0 ! 1 450 300 I50 0 Mg (11) 280270 nm I 6 0 0 I Mg ( I ) 285 213 nrn 300 I5O I i' 0 0 0 5 1 0 1 5 20 0 2 4 6 6 10 I2 14 16 6000 C a (11) 393.366 nrn 3000 Ca (11) 393.366 nm I I 1500 0 Z - ' I 1200 Ca (11) 396647 nm-1 L - 200 Ca (I) 422673 nm 300 C a ( I ) 422.673 nrn I I 0 0 0 5 10 1 5 2 0 3200 Sr (It) 407771 nm 2400 1600 800 0 1000 Sr (11) 421 552 nrn 2800 Sr (11) 407.771 nm 1 800 Sr (11) 421.552 nm 200 Sr ( I ) 460.733 nm 200 I Sr ( I ) 460.733 nrn 150 :::I =A,//?{ 50 0 0.0 0.5 1.0 1.5 2.0 0 2 4 6 8 10 12 14 16 Distance from orificehm Aerosol gas flow raten min-' Fig.7. Axial profiles of the optical emission of various atom (I) and ion (11) lines. The orifice used was 1.06 mm diameter. The background pressure in the extraction chamber was 9.5 Torr. The concentrations of these elements were 50 pg ml-' Fig. 8. Dependence of analyte line intensity on aerosol gas flow rate. The orifice used was 1.06mm diameter. The background pressure in the extraction chamber was 9.5 Torr. The concentrations of these elements were 50 pg ml-' hump behaviour is removed. The intensities of ion I1 lines are all maximized at 0.7-0.9 1 min-'. When the orifice diameter was enlarged to 1.06 mm all of the axial channel was sampled through the sampling orifice at all the aerosol gas flow rates studied." Apparently changes in the ion number density factor with aerosol gas flow rate became less significant instead the Boltzmann factor became dominant [eqn.(2)]. background pressure and larger orifice diameter. The axial profiles are maximized neither at the location of the Mach disc (7 mm) nor at the location of the second disc (14 mm). For the lines studied a viewing height 12 mm above the orifice was chosen to be the optimum viewing position. The effect of aerosol gas flow rate was also studied as shown in Fig. 8. The most striking result is that most of the double- of Analytical Atomic Spectrometry April 1996 Vol.1 1 251 JournalTable 2 Detection limits (DL) ~ ~~~ ~ Element Wavelength/nm Z,*/counts s-l Z,t/counts s-l a$/counts s-l DL§/ng ml-I Mg 279.553 Ca 393.366 Sr 407.771 41.8 98.2 51.2 0.20 0.16 0.19 0.08 1 0.072 0.077 6 2 4 * Z is the peak intensity of the analyte after background correction. 2o The analyte concentration is 1000 ng m1-l. 7 Zb is the net intensity of the spectral background at the wavelength of the peak maximum.20 1 a is the measured standard deviation of the background in counts s-l.” The standard deviation was calculated from ~ 2 0 independent tj DL is the analyte concentration that provides a net signal equal to three times the standard deviation of the blank”. measurements of the background. Detection Limits and Noise Sources Detection limits were measured for the most intense line for each element studied as shown in Table2.Operating con- ditions for these detection limits are as follows orifice diameter 1.06 mm; background pressure 9.5 Torr; viewing height 12 mm above the orifice; aerosol gas flow rate 0.8 1 min-’; and sampling time = integration time = 200 s. Detection limits were in the range of 2-6 ng ml-’ . These detection limits are respectable mainly because the background and the standard deviation of the background from the Mach disc remain low as seen previously.’ The main source of noise in the background can be estimated as follows. This discussion follows that of Barnard et ~ 1 . ’ ~ The detector accumulates photoelectrons. Fifteen such photoelectrons are needed to produce one count in the readout electronics and software.The dark current is typically 7-11 counts s-’ which would be 1400-2200 counts in the integration time used here (200 s). These values correspond to 21000 to 33000 electrons from the dark current. The software automatically subtracts the dark current so this dark current is not included in the background values shown in Table2 but the noise on the dark current remains. The standard deviation caused by shot noise on the dark current would be =(number of dark current electrons)’’’ which corresponds to 145-1 82 electrons or 10-12 counts. At the three wavelengths monitored the count rates shown for the standard deviation of the background corre- spond to 14-16 counts in the integration time used. Therefore shot noise in the dark current is the main component of the background noise especially since the total noise is the sum of the variances contributed by the various noise sources i.e.(ctotal)’ ZZ (a from various noise sources).’ The readout noise of 13 electrons (x 1 count) and additional digitizing noise” is negligible. The intensities shown in Table2 are still lower than those seen from the ICP” by factors of 100-1000. Obviously the analyte signal from the Mach disc must be enhanced further. Several possible ways to implement such enhancements are currently under investigation in this laboratory including backfilling the chamber with He applying r.f. voltage to an electrode located at a position downstream from the Mach disc and incorporating a magnetic mirror. Ideally these measures would enhance the analyte signal more than the background.The authors gratefully acknowledge Perkin-Elmer for the loan of the Optima 3000 atomic emission spectrometer. Ames Laboratory is operated by Iowa State University for the U.S. Department of Energy under contract No. W-7405-Eng-82. This research was supported by the Office of Basic Energy Sciences Division of Chemical Sciences. REFERENCES 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Houk R. S. and Lim H. B. Anal. Chem. 1986 58 3244. Winge R. K. Fassel V. A. Peterson V. J. and Floyd M. A. Inductively Coupled Plasma-Atomic Emission Spectroscopy. An Atlas of Spectral Information Elsevier Amsterdam 1985. Lim H. B. Houk R. S. Edelson M. C. and Carney K. P. J. Anal. At. Spectrom. 1989 4 365. Douglas D.J. and French J. B. J. Anal. At. Spectrom. 1988 3 743. Fraser R. B. Robben F. and Talbot L. Phys. Fluids 1971 14 2317. Kawaguchi H. Asada K. and Mizuike A. Mikrochim. Acta 1988 111 143. Gray A. L. J. Anal. At. Spectrom. 1989 4 371. Borer M. W. and Hieftje G. M. Spectrochim. Acta Reu. 1991 14 463. Borer M. W. and Hieftje G. M. J. Anal. At. Spectrom. 1993 8 333. Borer M. W. and Hieftje G. M. J. Anal. At. Spectrom. 1993 8 339. Shibata N. Fudagawa N. and Kubota M. Spectrochim. Acta Part B 1992 47 505. Barnard T. W. Crockett M. I. Ivaldi J. C. and Lundberg P. L. Anal. Chem. 1993 65 1225. Barnard T. W. Crockett M. I. Ivaldi J. C. Lundberg P. L. Yates D. A. Levine P. A. and Sauer D. J. Anal. Chem. 1993 65 1231. Houk R. S. Fassel V. A. Flesch G. D. Svec H. J. Gray A. L. and Taylor C. E. Anal. Chem. 1980 52 2283. Houk R. S. Fassel V. A. and Svec H. J. Dyn. Mass Spectrom. 1981 6 234. Ashkenas H. and Sherman F. S. in Rarefied Gas Dynamics Proceedings of the 4th International Symposium on Rarefied Gas Dynamics ed. de Leeuw J. H. Academic Press New York 1966 Koirtyohann S. R. Jones J. S. and Yates D. A. Anal. Chem. 1980,52 1966. Jarvis K. E. Gray A. L. and Houk R. S. Handbook of lnductively Coupled Plasma Mass Spectrometry Blackie Glasgow 1992. Douglas D. J. and French J. B. J. Anal. At. Spectrom. 1988 3 743. Ivaldi J. C. and Barnard T. W. Spectrochim. Acta Part B 1993 48 1265. Mermet J.-M. and Ivaldi J. C. J. Anal. At. Spectrom. 1993,8 795. VO~. 11 pp. 84-105. Paper 51041 76G Received June 28 1995 Accepted December 12 1995 252 Journal of Analytical Atomic Spectrometry April 1996 Vol. 11

ISSN:0267-9477    

DOI:10.1039/JA9961100247

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Study of the Effect of Organic Emulsified Samples in Inductively Coupled Plasma Atomic Emission Spectrometry 1 Journal of Analytical Atomic Spectrometry I MIGUEL MURILLO AND JOSE CHIRINOS" Centro de Quimica Analitica Facultad de Ciencias Universidad Central de Venezuela P.O. Box 471 02 Caracas 1041 -A Venezuela A study of the plasma discharge was carried out in order to evaluate the possible effects of the introduction of emulsified samples. Several plasma diagnostic parameters such as excitation temperature electron number density ionic-to- atomic intensity ratio and atomic-to-molecular carbon intensity ratio were measured. Organic solvents with different evaporation factors and crude oil were used as the oil phase in the emulsion. Typical operating conditions for ICP-AES were employed for all the experiments.Generally the results show that an oil phase such as xylene in the emulsion can perturb the plasma discharge processes. Also an evaluation of the diagnostic parameters shows that a crude oil in water emulsion has a similar effect to an aqueous solution on the plasma discharge. This result confirms that plasma emission is mainly perturbed by the volatility of the organic material in the emulsion. Keywords Inductively coupled plasma atomic emission spectrometry; organic solvent; emulsion ICP-AES has been extensively used as an excitation atomiz- ation and ionization source in analytical atomic spectrometry.' The ICP is considered to be an ideal source for emission spectrometry because it is free of matrix interferences mainly due to the high temperature rises in the plasma discharge.2 It has been demonstrated that the composition of the sample matrix may produce unpredictable changes in the emission intensity of the analyte which may affect the accuracy and precision in the quantification of trace elements under particu- lar experimental condition^.^-' The matrix interferences can be produced by inorganic acid,3 easily ionizable elements4 or organic solvent^.^ The application of ICP-AES to the determination of trace elements in organic solvent media has been well docu- mented.5-1' The three main applications include analysis of samples dissolved directly in organic solvents,' e.g.petroleum products analysis of organic extracts" and element-specific detection for liquid chromatography." A net analyte signal suppression in the presence of certain volatile organic solvents has been rep~rted.'?'~-~~ This phenomenon has been attributed to the presence of a high organic vapour loading which can absorb rf power in the central channel of the plasma thus lowering its excitation temperature and decreasing the analytical signal.The analysis of samples dissolved in organic solvents with greater volatility than water requires different ICP-AES operating conditions compared with those used for aqueous solution^,'^-^^ including the use of a condenser after the spray chamber to remove the excess of solvent vapour an increase in the forward power and the plasma gas flow rate to protect the torch and the addition of oxygen to the plasma to achieve solvent vapour combustion. As an alternative to the use of organic solvents the samples * To whom correspondence should be addressed.can be emulsified in water. The use of emulsions can reduce the organic content of the sample solution to less than 95% m/m. Previous studies have reported the use of emulsion systems for sulfur and trace metal determination in lubricating oil and crude oils with good accuracy and These workers have reported that emulsion sample preparation is extremely rapid and the matrix interference experienced with organic solvents such as solvent loading are avoided because of the reduction of the organic content of the sample solution. Generally emulsified inorganic aqueous solutions were used as calibration standards for trace element determinations in crude oil and lubricating oils showing that some matrix interference was produced by the emulsified solutions.This work presents an evaluation of several spectroscopic diagnostic parameters when emulsified organic samples are nebulized in order to obtain information on the possible effect of these samples on the plasma discharge. PROCEDURES Several emulsions with different oil phases were nebulized under typical operating conditions of the plasma. Diagnostic parameters such as plasma background emission excitation temperature electron number density ionic-to-atomic intensity ratio and atomic-to-molecular carbon intensity ratio were evaluated for each of these emulsions and the results were compared with those obtained for an aqueous solution. Emulsion Preparation An appropriate portion of the organic phase was mixed with 0.40 g of emulsifier and the mixture was mechanically agitated until a homogeneous solution phase was obtained.De-ionized water was then added with continual agitation until a final mass of 20 g was obtained. Plasma Diagnostic Parameters The Boltzmann plot method was used to measure the average excitation temperat~re.'~ Vanadium was selected as the ther- mometric element and the lines used are listed in Table 1. These lines were carefully selected in order to avoid carbon spectral interferences. Measured line intensities were fitted with Table 1 Vanadium lines used for excitation temperature determination22 Wavelengt h/nm 292.4 292.46 297.62 297.65 303.38 309.31 311.07 311.84 Excitation energy/cm - 37 352 37 151 47 102 47 181 47 608 35 483 34 947 34 746 1 Log (gf) 0.75 0.56 0.67 1.17 1.12 0.79 0.56 0.42 Journal of Analytical Atomic Spectrometry April 1996 Vol.1 1 (253-257) 253a least-squares routine using standard computer software. The values of log (IA3/gf) were plotted against excitation energy and excitation temperatures were calculated from the line slopes. Log gfvalues were taken from Corliss and Bozman.22 The experimental standard deviation of the temperature was 100 K based on three repetitive measurements. The HP line at 486.1 nm was employed for determining the average electron number density using Griem's approxi- m a t i ~ n . ' ~ Mg I1 280.270 to Mg I 285.2 nm lines were used to obtain ionic-to-atomic line intensity ratio^.'^ Molecular carbon and atomic carbon13 were measured at 436.92 and 199.301 nm respectively.EXPERIMENTAL Instrumentation The inductively coupled plasma spectrometer employed in this study was a Jobin-Yvon (Longjumean France) Model JY24 instrument. Details of the instrument and the operating con- ditions used are listed in Table 2. Reagents Magnesium and vanadium solutions were obtained from 1000 pg ml-' (BDH Poole Dorset UK) stock solutions. Ethoxy nonylphenol (Etoxyl Maracaibo Venezuela) was used as emulsifier. Nitrobenzene (BDH) isobutyl methyl ketone (IBMK) (BDH) sulfur-free xylene (BDH) and Venezuelan crude oil were used as oil phases in the emulsion samples. De-ionized water (Milli-Q grade) was used throughout. RESULTS AND DISCUSSION Effect of the Volatility of the Oil Phase of the Emulsion on Plasma Excitation Temperature Previous studies carried out with organic solvents have reported a decrease in the excitation temperature in the plasma owing to the extra energy consumption required to decompose the organic matter."-l7 This effect depends on the volatility of the solvent.Hence a study of the excitation temperature of the plasma was carried out in the presence of some oil in water emulsions. The oil phases used in the emulsion were xylene IBMK and nitrobenzene. These solvents have evaporation rates of 77.3 18.5 and 4.09 pm3 s-' respectively. A crude oil in water emulsion was also studied. The temperatures were obtained by using two different nebulizer gas flow rates uiz. 0.5 and 0.7 1 min-' . The excitation temperatures obtained for the emulsions are presented in Table 3.It can be seen that a reduction of approximately 150 K is observed with the introduction of the emulsions with a solvent of greater volatility (xylene and IBMK) when Table 2 Instrumental and experimental parameters Spectrometer Grating Rf generator Forward power Nebulizer Spray chamber Coolant gas flow rate Auxiliary gas flow rate Sheath gas flow rate Nebulizer gas flow rate Purge gas flow rate Observation height in the plasma Measurement time Jobin-Yvon Model JY 24 Holographic grating having 3600 grooves mm-' 40 MHz 900 W Meinhard C type Scott type 12 1 min-' 2 1 min-' 0.1 1 min-' 0.9 1 min-' 10 1 min-' 15 mm above load coil 0.5 s (with peristaltic pump) Table3 Excitation temperatures of the plasma in the presence of the emulsions Evaporation Oil phase of factor 'E' the emulsion pm3 s-' IBMK 77.3 Xylene 18.5 Aqueous 13.1 'Nitrobenzene 4.09 solution Nebulizer gas flow 1 min-' 0.50 0.70 0.50 0.70 0.50 0.70 0.50 0.70 Excitation temperature/K 4915 4538 4959 4416 5000 4616 4861 4639 compared with the temperature obtained for a nitrobenzene in water emulsion and an aqueous solution.These results indicate that the solvent load produced by the emulsion did not have a significant effect on the excitation temperature of the plasma discharge. The reduction of the excitation tempera- ture when the nebulizer gas flow rate is changed from 0.5 to 0.7 1 min-l is mainly attributed to a reduction of the residence time of the analyte in the plasma discharge.' Study of the ICP Background Emission Predominantly it has long been recognized that atomic carbon diatomic carbon and cyanide radicals contribute to ICP back- ground emission when a solution containing organic matter or an organic solvent is introduced into the ICP and that the intensities of these various species vary with the ICP excitation conditions.The background caused by carbon species worsens the detection limits by adversely affecting the signal-to- background ratios.' Scans of the ICP background emission give an excellent over-all impression of the wavelength region where molecular bands dominate the spectrum and where interferences can be expected. Hence the ICP background emission was scanned when xylene in water and crude oil in water emulsions were nebulized. Xylene in water emulsion Scans of the plasma background emission with the introduction of xylene in water emulsions and an aqueous solution (used as reference) are shown in Fig. 1.The background of an aqueous solution (curve a) and a xylene in water emulsion (curve b) exhibit considerable differences. The intensity of the back- ground with xylene in water emulsions is greater than that obtained for the aqueous solution in three well-defined zones from 200 to 260nm from 340 to 400nm and from 440 to 480nm. The intensities of this region increase as the xylene concentration increases (curve c) indicating that this effect is produced by molecular carbon emissions due to incomplete combustion of the organic matter from the emulsion. These c 4 E W 200 220 240 260 280 300 310 340 360 380 400 425 440 460 480 500 Wavelengthhm Fig.1 Plasma background emission with introduction of a aqueous solution; b xylene (1%) in water emulsion; and c xylene (1.5%) in water emulsion. Sheath and auxiliary gases flowing 254 Journal of Analytical Atomic Spectrometry April 1996 Vol. 11molecular emissions may produce spectral interferences with analytical lines located in this zone demonstrating that xylene in water emulsions perturb the plasma discharge processes. Crude oil in water emulsion The ICP background emission with crude oil in water and crude oil plus xylene in water emulsions was compared with the plasma background emission obtained when an aqueous solution and a xylene in water emulsion were nebulized. The results are presented in Fig. 2. It can be seen that the crude oil in water emulsion exhibits a similar background to the aqueous solution indicating that the organic matter from the crude oil does not contribute significantly to the ICP back- ground continuum.On the other hand the crude oil plus xylene in water emulsion exhibits a similar background to the xylene in water emulsion demonstrating that whole organic materials do not affect the plasma discharge significantly in contrast to the volatile material of the emulsion. Eflect of sheath and auxiliary gas$ow rates The ICP background emission when a xylene in water emulsion was nebulized was studied under different sheath and auxiliary gas flow rates. These gases are used to avoid any carbon deposition on the inner wall of the injector25 and on the torch L .$ 200 Y - 150 2 .g 100 5 50 .v 0 .- v) I >f 200 240 280 310 360 400 440 480 Wavelengthhm Fig.2 Plasma background emission with a aqueous solution; b crude oil; c crude oil with xylene in water emulsion; and d xylene in water emulsion. Sheath and auxiliary gases flowing h 250 200 220 240 300 310 340 360 38C 400 440 460 Wavelengthhm Fig.3 Plasma background emission with a auxiliary and sheath gases absent; b auxiliary gas present and sheath gas absent; c auxiliary gas absent and sheath gas present; d auxiliary and sheath gases present surface.17 It can be seen from Fig. 3 that the background is modified by the presence of sheath and auxiliary gases giving a higher emission in the zone attributed to carbon band emissions. This result contrasts with that obtained for an aqueous solution where the presence of these gases does not affect the ICP background emission. The differences in the magnitude of the background obtained for a xylene in water emulsion can be attributed to plasma excitation changes and this aspect is discussed further.Diagnostic Parameters Knowledge of various parameters of the plasma such as excitation temperature electron number density ionic-to- atomic intensity line ratio and atomic-to-molecular carbon intensity ratio (C1:C,) is necessary to describe some of the properties of the discharge and is useful to explain line intensities line widths and background intensities for analytical purposes.24 The above-mentioned parameters were measured for xylene in water crude oil in water and crude oil with xylene in water emulsions and the results were compared with those obtained for an aqueous solution.The results are pre- sented in Table 4. It can be seen that the diagnostic parameters obtained when a crude oil in water emulsion is nebulized into the plasma show similar values to those obtained for an aqueous solution. When a crude oil with xylene in water emulsion is nebulized the diagnostic parameters are similar to those obtained for xylene in water emulsions. These results explain the background differences exhibited by the emulsions in Fig. 1 and confirm that a crude oil in water emulsion does not provide a considerable amount of organic material that could affect the plasma excitation conditions significantly. The presence of volatile material in the emulsion is the main factor affecting the plasma excitation changes.Several diagnostic parameters were obtained when a xylene in water emulsion was nebulized in the presence or absence of the auxiliary and sheath gases. Diagnostic parameters for an aqueous solution were also obtained for comparative purposes. The results are presented in Table5 It can be seen that the diagnostic parameters obtained for a xylene in water emulsion and an aqueous solution are similar in the absence of the auxiliary and sheath gases. Furthermore a reduction of the values of these parameters is observed when both gases are used simultaneously. This deterioration of the excitation con- ditions of the plasma may be due to the introduction of volatile solvent from the emulsion into the plasma.Also the auxiliary and sheath gases do not permit an effective interaction of the energy of the plasma with the sample. By analysing the C1:Cz ratio obtained for the xylene in water emulsion it is apparent that a minimum value for this ratio is found when both the auxiliary and sheath gases are flowing. This trend is similar to that found for the excitation temperature and electron number density when these additional flows of argon are introduced. This deterioration of the C1:Cz ratio is caused by a deterioration of the excitation conditions of the plasma which increases the emission of molecular carbon. The effect of auxiliary and sheath gas flow rates on the basic properties of the plasma explains the changes Table 4 Excitation temperature electron number density ionic-to-atomic intensity line ratio and atomic-to-molecular carbon intensity ratio for aqueous solution xylene in water emulsion crude oil in water emulsion and crude oil with xylene in water emulsion. Auxiliary and sheath gases present Temperature/ YIl Solution K cm-3 Mg I1 Mg I c c Aqueous solution 4725 1.48 4.36 Xylene in water emulsion 4403 1.04 6.78 18.05 Crude oil in water emulsion 4578 1.42 4.90 - Crude oil and xylene in water emulsion 4398 1.02 6.57 15.42 - Journal of Analytical Atomic Spectrometry April 1996 Vol.11 255Table 5 Excitation temperature electron number density ionic-to-atomic intensity line ratio and atomic-to-molecular carbon intensity ratio for aqueous solution and xylene in water emulsion using sheath and auxiliary gases - Solution Sheath Auxiliary Temperature/ v/ gas flow* gas flow* K cm-3 Mg I1 Mg I c1 cz Aqueous solution + - + - Xylene in water emulsion + - 4725 4650 4618 4626 4403 4506 - 1.48 4.36 1.52 4.29 1.61 4.60 1.64 4.50 1.04 6.78 18.05 1.06 7.08 18.07 - - - + - 4560 1.25 6.16 18.47 - - 4604 1.39 5.90 18.58 * + Gas flow present; - gas flow absent.250 1 200 220 240 300 310 340 360 380 400 440 460 Wavelengthlnm Fig. 4 Plasma background emission with a auxiliary and sheath gases absent; b auxiliary gas present and sheath gas absent; c auxiliary gas absent and sheath gas present; and d auxiliary and sheath gases present observed in the background continuum obtained when a xylene in water emulsion is nebulized (Fig. 3). Also these results are in agreement with those obtained by Pan et al.I7 and Murillo and Mermet.26 They concluded that the optimum excitation and atomization properties of the plasma are obtained with the lowest possible auxiliary and sheath gas flow rates.By analysing the diagnostic parameters for an aqueous solution it is apparent that these parameters do not exhibit considerable changes in the presence or absence of the sheath and auxiliary gases. For the aqueous solution the C C2 ratio is not reported as this solution did not give rise to molecular carbon emissions. These results indicate that the excitation conditions of the plasma are not affected by the presence of the auxiliary and sheath gases and they are in agreement with the ICP background emission obtained in Fig. 4. Effect of the Concentration of Oil Phase in the Emulsion A study of the effect of the oil phase concentration on the plasma discharge was carried out.For this purpose xylene in water emulsions were studied. Atomic-to-molecular carbon intensity ratios were used as the diagnostic parameter. The C1 C2 ratio as a function of the nebulizer gas flow for xylene in water emulsions is presented in Fig. 5. It can be seen that the C1 C2 ratio remains almost constant for values of nebulizer gas flow of 0.5 and 0.6 1 min-l. This relationship is signific<antly depressed when higher values of nebulizer gas flow are employed owing to an increase in the molecular carbon emission. Also when molecular carbon and atomic carbon intensity ratios are studied for all the nebulizer gas flow rates used it is apparent that there is a reduction of this intensity ratio.The worsening of the C Cz ratio either by using higher values of the nebulizer gas flow rate or by using higher xylene concentrations in the emulsions can be attributed to an increase in the solvent load which increases the amount of organic matter that cannot be decomposed totally in the plasma. 256 Journal of Analytical Atomic Spectrometry April 1996 U 1.5 2:o 2:5 3:O Xylene concentration (% m/m) Fig.5 C1:C ratio as a function of xylene concentration in the emulsion A nebulizer gas flow 0.5 1 min-l; * nebulizer gas flow 0.6 1 min-'; 0 nebulizer gas flow 0.7 1 min-'; and El nebulizer gas flow 0.8 1 min-l. Sheath and auxiliary gases flowing. When a similar study was carried out using crude oil in water emulsions the results showed that these emulsions did not exhibit molecular carbon emissions demonstrating that an efficient decomposition of organic matter was accomplished under the working conditions used.The crude oil concentration in the emulsion was 5.0% m/m which is the maximum value at which a stable emulsion can be obtained. CONCLUSIONS The presence of carbon molecular emissions in the plasma when xylene in water emulsions are nebulized in the plasma demonstrates that there is incomplete combustion of the organic matter that is introduced into the plasma. When aqueous solutions are nebulized in the plasma dis- charge the emission of the background is not affected signifi- cantly by the presence or absence of the sheath and auxiliary gases; in addition the excitation temperature electron number density and Mg 1I:Mg I ratio are not seriously affected. However when a xylene in water emulsion is introduced the diagnostic parameters are affected both in the presence and absence of the auxiliary and sheath gases.The diagnostic parameters of the plasma when a crude oil in water emulsion is introduced into the plasma exhibit similar values to those for aqueous solutions indicating that it is the introduction of the volatile material that disturbs the plasma discharge. This can result in an inefficient supply of energy from the plasma to the sample. This effect increases as the concentration of volatile material in the emulsion increases. This work was supported by the Consejo Nacional de Investigaciones Cientificas y Tecnologicas (Research Grant 184-93).The authors appreciate the help provided by Dr. Albert0 Fernandez in preparing the manuscript. REFERENCES 1 Boumans P. Inductively Coupled Plasma Emission Spectroscopy Part I Wiley New York 1987 ch. 4. vd. 1 12 8 9 10 11 12 13 14 Fassel V. Plenary Lectures and Reports of 16th Colloquium Spectroscopicurn Internationale ed Kaiser H. Hilger London 1972 p. 63. Fernandez A. Murillo M. Carrion N. and Mermet J. M. J. Anal. At. Spectrom. 1994 9 217. Tripkovic M. and Holclajtner-Antunovic I. J. Anal. At. Spectrom. 1993 8 349. Boumans P. and Lux-Steiner M. Spectrochim. Acta Part B 1983 38 81. Merryfield R. and Loyd R. Anal. Chem. 1979 51 1965. Merryfield R. N. and Runnels J. H. in Developments in Atomic Plasma Spectrochemical Analysis ed.Barnes R. M. Heyden Philadelphia PA 1981 pp. 396-403. Jansen E. Knipscheer J. and Nagtegaal M. J. Anal. At. Spectrom. 1992 7 1274. Milner 0. J. Analysis of Petroleum for Trace Elements Pergamon New York 1963 pp. 68 and 97-98. Seeverens P. Klaeassen E. and Maessen F. Spectrochim. Acta Part B 1983,38 727. Hausler D. and Taylor L. Anal. Chem. 1981 53 1227. Pan C. Guangxuan Z. and Browner R. J. Anal. At. Spectrom. 1990 5 537. Boumans P. Inductively Coupled Plasma Emission Spectroscopy Part 11 Wiley New York 1987. Fabec J. and Ruschak M. Anal. Chem. 1985 57 1853. 15 16 17 18 19 20 21 22 23 24 25 26 Barret P. and Prusekowska E. Anal. Chem. 1984 56 1927. Kreuning G. and Maessen J. Spectrochim. Acta Part B 1989 44 367. Pan C. Guangxuan Z. and Browner R. J. Anal. At. Spectrom 1992 7 1231. Lord C. Anal. Chem. 1991,63 1594. Borszeki J. Knapp G. Halmos P. and Bartha L. Mikrochim. Acta 1992 108 157. Murillo M. and Chirinos J. J. Anal. At. Spectrom. 1994 9 237. Murillo M. Gonzalez A. Ramirez A. and Guillen N. At. Spectrosc. 1994 15 90. Corliss C. and Bozman W. Experimental Transition Probabilities for Spectral Lines of Seventy Elements NBS Monograph 53 The Superintendent of Documents Washington DC 1968. Hill R. J. Quant. Spectrosc. Radiat. Transf. 1964 4 857. Mermet J. Anal. Chim. Acta 1991 250 855. Mermet J. Ripoche P. and Trassy C. in Developments in Atomic Spectrochemical Analysis ed. Barnes R. M. Heyden London 1981 p. 718. Murillo M. and Mermet J. Spectrochim. Acta Part B 1987 42 1151. Paper 51057248 Received August 30 1995 Accepted December 21 1995 Journal of Analytical Atomic Spectrometry April 1996 Vol. 11 257

ISSN:0267-9477    

DOI:10.1039/JA9961100253

出版商:RSC    

年代:1996

数据来源: RSC