摘要:

JASPE2 8(8j 61 N-66N 1053-1 122 337R-405R 9 9 ) Typeset by Burgess Thames View Abingdon Oxfordshire December 1993 Printed in Great Britain by Journal of Analytical Atomic Spectrometry Including Atomic Spectrometry Updates CONTENTS NEWS AND VIEWS 61 N Obituary-David A Hickman 61 N Reconstruction of Boris L'vov's Electrothermal Atomizer-Judith Egan-Shuttler 61 N Gordon Kirkbright Bursary 62N Book Review-Adam McMahon 63N Diary of Conferences and Courses 65N Future Issues PAPERS 1053 1059 1067 1075 1085 1091 1097 1103 1109 1113 1117 1121 Determination of Ultratrace Levels of Heavy Metals in Arctic Snow by Electro- thermal Vaporization Inductively Coupled Plasma Mass Spectrometry-Ralph E Sturgeon Scott N Willie James Zheng Akira Kudo D Conrad Gregoire Determination of Palladium and Platinum in Fresh Waters by Inductively Coupled Plasma Mass Spectrometry and Activated Charcoal Preconcentration-Gwendy E M Hall J C.Pelchat Determination of Selenium in Marine Certified Reference Materials by Hydride Generation Inductively Coupled Plasma Mass Spectrometry-Hiroaki Tao Joseph W H Lam James W McLaren Arsenic Speciation in Seafood Samples With Emphasis on Minor Constituents an tnvestigation Using High-performance Liquid Chromatography With Detection by Inductively Coupled Plasma Mass Spectrometry-Erik H Larsen Gunnar Pritzl Steen Honore Hansen Speciation of Arsenic by Ion Chromatography and Off -line Hydride Generation Electrothermal Atomic Absorption Spectrometry-Han Heng-bin Liu Yan-bing Mou Shi-fen Ni Zhe-mmg Electrothermal Vaporization for Sample Introduction in Microwave-induced Plasma Atomic Absorption Spectrometry-Ytxiang Duan Xingyou Li Qinhan Jin Improvement in Mercury Cold Vapour Atomic Techniques by Resorting to Organized Assemblies and On-line Membrane Drying of Vapour-B Aizpun Fernandez M R Fernandez de la Campa Alfred0 Sanz-Medel Improvement in Detection Limits in Graphite Furnace Diode Laser Atomic Absorption Spectrometry by Wavelength Modulation Technique.Plenary Lecture-Christoph Schnurer-Patschan Aleksandr Zybin Henning Groll Kay Niemax Preliminary Study on the Use of Palladium as a Chemical Modifier for the Determination of Silicon by Electrothermal Atomic Absorption Spectrometry-Zhixra Zhuang Pengyuan Yang Xiaoru Wang Zhiwei Deng Benli Huang Effect of Aqueous Organic Solvents on the Determination of Trace Elements by Flame Atomic Absorption Spectrometry and Inductively Coupled Plasma Atomic Emission Spectrometry-M Todorovic S Vidovic.Z IIIC Indirect Flame Atomic Absorption Spectrometric Determination of Papaverine Strychnine and Cocaine by Continuous Precipitation With Dragendorff's Reagent-Marceltna Eisman Mercedes Gallego Miguel Valcarcel CUMULATIVE AUTVOR INDEX ATOMIC SPECTROMETRY 337R Industrial Analysis Metals Chemicals and Advanced Materials-John Marshall UPDATE John Carroll James S. Crighton Charles L. R. Barnard 377R References continued on inside back cover 0267-9477C199318:l-YJASPE2 8(8j 61 N-66N 1053-1 122 337R-405R 9 9 ) Typeset by Burgess Thames View Abingdon Oxfordshire December 1993 Printed in Great Britain by Journal of Analytical Atomic Spectrometry Including Atomic Spectrometry Updates CONTENTS NEWS AND VIEWS 61 N Obituary-David A Hickman 61 N Reconstruction of Boris L'vov's Electrothermal Atomizer-Judith Egan-Shuttler 61 N Gordon Kirkbright Bursary 62N Book Review-Adam McMahon 63N Diary of Conferences and Courses 65N Future Issues PAPERS 1053 1059 1067 1075 1085 1091 1097 1103 1109 1113 1117 1121 Determination of Ultratrace Levels of Heavy Metals in Arctic Snow by Electro- thermal Vaporization Inductively Coupled Plasma Mass Spectrometry-Ralph E Sturgeon Scott N Willie James Zheng Akira Kudo D Conrad Gregoire Determination of Palladium and Platinum in Fresh Waters by Inductively Coupled Plasma Mass Spectrometry and Activated Charcoal Preconcentration-Gwendy E M Hall J C.Pelchat Determination of Selenium in Marine Certified Reference Materials by Hydride Generation Inductively Coupled Plasma Mass Spectrometry-Hiroaki Tao Joseph W H Lam James W McLaren Arsenic Speciation in Seafood Samples With Emphasis on Minor Constituents an tnvestigation Using High-performance Liquid Chromatography With Detection by Inductively Coupled Plasma Mass Spectrometry-Erik H Larsen Gunnar Pritzl Steen Honore Hansen Speciation of Arsenic by Ion Chromatography and Off -line Hydride Generation Electrothermal Atomic Absorption Spectrometry-Han Heng-bin Liu Yan-bing Mou Shi-fen Ni Zhe-mmg Electrothermal Vaporization for Sample Introduction in Microwave-induced Plasma Atomic Absorption Spectrometry-Ytxiang Duan Xingyou Li Qinhan Jin Improvement in Mercury Cold Vapour Atomic Techniques by Resorting to Organized Assemblies and On-line Membrane Drying of Vapour-B Aizpun Fernandez M R Fernandez de la Campa Alfred0 Sanz-Medel Improvement in Detection Limits in Graphite Furnace Diode Laser Atomic Absorption Spectrometry by Wavelength Modulation Technique.Plenary Lecture-Christoph Schnurer-Patschan Aleksandr Zybin Henning Groll Kay Niemax Preliminary Study on the Use of Palladium as a Chemical Modifier for the Determination of Silicon by Electrothermal Atomic Absorption Spectrometry-Zhixra Zhuang Pengyuan Yang Xiaoru Wang Zhiwei Deng Benli Huang Effect of Aqueous Organic Solvents on the Determination of Trace Elements by Flame Atomic Absorption Spectrometry and Inductively Coupled Plasma Atomic Emission Spectrometry-M Todorovic S Vidovic. Z IIIC Indirect Flame Atomic Absorption Spectrometric Determination of Papaverine Strychnine and Cocaine by Continuous Precipitation With Dragendorff's Reagent-Marceltna Eisman Mercedes Gallego Miguel Valcarcel CUMULATIVE AUTVOR INDEX ATOMIC SPECTROMETRY 337R Industrial Analysis Metals Chemicals and Advanced Materials-John Marshall UPDATE John Carroll James S. Crighton Charles L. R. Barnard 377R References continued on inside back cover 0267-9477C199318:l-Y

ISSN:0267-9477    

DOI:10.1039/JA99308FX025

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

JASPE2 8(6) 45N-51 N 767-934 September 1993 Typeset by Burgess Tharnes View Abingdon Qxfordshire Journal of Analytical Atomic Spectrometry 1993 EUROPEAN WINTER CONFERENCE ON PLASMA SPECTROCHEMISTRY GRANADA SPAIN JANUARY 10-1 5 1993 CONTENTS NEWS AND VIEWS 45N Foreword-Alfred0 Sanz-Medel 46N Obituary-Woicieth Vieth 47N Diary of Conferences and Courses 50N Papers in Future Issues PAPERS PLENARY LECTURE 767 Developments and Trends in Plasma Spectrochemistry-A View-Paul Boumans INVITED LECTURES 781 Inductively Coupled Plasma Mass Spectrometry of Biological Samples- Carlo Vandecasteele Hans Vanhoe Richard Dams 787 Potential of Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry for Trace! Metal Speciation-Nohora P. Vela. Joseph A. Caruso 795 803 809 81 5 821 827 833 839 843 Real-time Internal Standardization for Inductively Coupled Plasma Atomic Emission Spectrometryl Using a Custom Segmented-array Charge Coupled Device Detector-Jean-Michel Illermet Juan C lvaldi Comparison of Optical Emission Spectrometric Measurements of the Concentration and Einergy of Species in Low-pressure Microwave and Radiofrequency Plasma Sources-Yurgen Ropcke Andreas Ohl Martin Schmidt Simultaneous Multi-element Determination Using Helium or Argon Plasma for Graphite Furnace Capacitively Coupled Plasma Atomic Emission Spectrometry-Glen F R Gilchrist Peter M Celliers Huacheng Yang Changbin Yu Dong C Liang Vesicle-mediated High-performance Liquid Chromatography Coupled to Hydride Generation Inductively Coupled Plasma Atomic Emission Spectrometry for Speciation of Toxicologically Important Arsenic Species-Yi Ming Lu Maria Luisa Fernandez Sanchez Elisa Blanco Gonzalez Alfredo Sanz-Medel Sensitive Method for Determination of Lead by Potassium Dichromate-Lactic Acid Hydride Generiation Inductively Coupled Plasma Atomic Emission Spectrometry-M C L'aldes-Hevia y Ternprano M R Fernandez de la Campa Alfredo S a nz- M ed e I Boron Determination in Steels by Inductively Coupled Plasma Atomic Emission Spectrometry.Comparative Study of Spark Ablation and Pneumatic Nebulization Sampling Systems -Aurora G Coedo Teresa Dorado Ester Escudero Isabel G Coba Application of Ultrasonic Nebulization for the Determination of Rare Earth Elements in Phosphates and Related Sedimentary Rocks Using Inductively Coupled Plasma Atomic Emission Spectrometry with Comments on Dissolution Procedures-I B Brenrier E Dorfrnan Analysis of Glasses froim the V20,-As203-Ba0 System Using Inductively Coupled Plasma Atomic Emission Spectrometry-S Del Barrio R Benito F J Valle Determination of Nickel Biological Samples by Inductively Coupled Plasma Atomic Emission Spectrometry After Extraction With 1.5-Bis[phenyl(2- pyridyl)methylene]thioc:arbonohydrazide-E Vereda Alonso A Garcia de Torres J M Can0 Pavon continued on inside back cover847 853 859 867 875 881 891 899 905 91 1 91 5 921 927 933 Generation of Volatile Cadmium Species With Sodium Tetrahydroborate From Organized Media Application to Cadmium Determination by Inductively Coupled Plasma Atomic Emission Spectrometry-M C Valdes-Hevia y Temprano M R Fernandez de la Campa Alfredo Sanz-Medel Microwave Digestion Methods for the Atomic Spectrometric Determination of Some Elements in Biological Samples-M D Mingorance M L Perez-Vazquez M Lachica Consideration of the Chemical Reactivity of Trace Impurities Present in a Glow Discharge-S K Ohorodnik S DeGendt S L Tong W W Harrison Optimization of Quantitative Depth Profiling With Glow Discharge Mass Spectrometry-Angelika Raith Robert C Hutton John C Huneke Analysis of Soils by Glow Discharge Mass Spectrometry-Douglas C Duckworth Christopher M Barshick David H Smith Analysis of Aluminium Oxide Powder by Glow Discharge Mass Spectrometry With Low Mass Resolution-Jin Chun Woo Norbert Jakubowski Dietmar Stuewer Plasma Temperature From Ion Kinetic Energies and Implications for the Source of Diatomic Oxide Ions in Inductively Coupled Plasma Mass Spectrometry-Scott D Tanner Noise in Inductively Coupled Plasma Mass Spectrometry Some Preliminary Measurements-Ahmet T Ince John G Williams Alan L Gray Determination of Aluminium by Inductively Coupled Plasma Mass Spectrometry in Serum of Patients Treated by Haemodialysis Dialysis Solutions and Tap Water and a Comparison with Atomic Absorption Spectrometry-Pier Luigi Trentini Monica Ascanelli Bernardette Zanforlini Francesco Venturini Gianna Bucci Francesco Fagioli Profile of Serum Silicon in Aluminium-overloaded Patients on Regular Haemodialysis Treatment-lbrahim H Fahal Rasheed Ahmad Gordon M Bell James D Birchall Norman B Roberts Concentration and Distribution of Silicon in Uremic Serum and Its Relation to Aluminium Levels-Kasia Wrobel Elisa Blanco Gonzalez Alfredo Sanz-Medel Anion Exchange for the Determination of Arsenic and Selenium by Inductively Coupled Plasma Mass Spectrometry-Jan Goossens Luc Moens Richard Dams Detection Limits Versus Matrix Effects Analysis of Solutions With High Amounts of Dissolved Solids by Flow Injection Inductively Coupled Plasma Mass Spectrometry-Peter Richner Cumulative Author Index

ISSN:0267-9477    

DOI:10.1039/JA99308BX027

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

1 994 Winter Conference on Plasma Spectrochemistry January 10 - 15 1994 San Diego California The 1994 Winter Conference on Plasma Spectrochemistry eighth in a series of biennial meetings sponsored by the ICPlnfonnation Newsletter features developments in plasma spectrochemical analysis by inductively coupled plasma (ICP) dc plasma (DCP) microwave plasma (MIP) and glow and hollow cathode discharge (GDL HCL) sources. The meeting will convene Monday January 1 Othrough Saturday January 15,1994 at the San Diego Princess Convention Center in San Diego California. Continuing education short courses at introductory and advanced levels will be offered Friday through Sunday January 7 - 9. A three-day exhibition of spectroscopic instrumentation and accessories also will be presented. The 6th Winter Conference on flow Injection Analysis will be held immediately before the meeting on January 5 to 7.Objectives and Program The rapid growth in popularity of plasma sources for atomization and excitation in atomic spectroscopy and ionization in mass spectrometry and the need to discuss recent developments of these discharges in spectrochemical analysis stimulated the organization of this meeting. The Conference will bring together international scientists experienced in applications instrumentation and theory in an informal setting to examine recent progress in the field. Approximately 500 participants from 25 countries are expected to attend. Approximately 200 papers describing applications fundamentals and instrumental developments with plasma sources will be presented in lecture and poster sessions by about 150 authors.Symposia organized and chaired by recognized experts will include the following topics 1) Sample introduction and transport phenomena 2) Flow injection spectrochemical analysis 3) Elemental speciation with plasma/ chromatographic techniques 4) Plasma instrumentation including chemometrics expert systems on-line analysis software and remote- system automation 5) Sample preparation treatment and automation 6) Excitation mechanisms and plasma phenomena 7) Spectroscopk standards and reference materials 8) Plasma source mass spectrometry 9) Solid sample analysis with glow discharges and laser-assisted plasma spectrometry and 10) Interferometry and plasma atomic fluorescence spectrometry.Six plenary and 18 invited lectures will highlight advances in these areas. Three afternoon poster sessions will feature applications automation and new instrumentation. Five panel discussions will address critical development areas in sample introduction automation elemental speciation practical plasma source mass spectrometry and novel software and hardware directions. Plenary invited and submitted papers will be published after peer review in September 1994 in the Journal of Analytical Atomic Spectrometry as the official Conference proceedings. Instrument Exhibition A three-day exhibition of spectroscopic instrumentation and chemicals electronics glassware publications and software supporting plasma spectroscopy will complement the scheduled sessions on Tuesday through Thursday January 1 1 - 13 with approximately 30 firms participating.Invited Speakers Invited speakers indude M. Blades P. Boumans J. Broekaert R. Browner J. Caruso R. Cornelis M.B. Denton L Ebdon P. Farnsworth W. Harrison K.G. Heumann G. Hieftje G. Horlick R.S. Houk H.M. Kingston J. Koropchak R.K. Marcus J. Mclaren J.M. Mermet J. Olesik J. Ruzicka D. Stuewer W. Wegscheider and J. D. Winefordner. Continuing Education Short Courses Introductory and advanced four-hour short courses will be presented Friday through Sunday January 7 - 9. Designed to provide background and intensive training in popular topics of plasma spectrochemistry these 65 courses feature analysis methods flow injection analysis instrumentation sample introduction and various plasma-related techniques.Social Activities The Conference will be held at the San Diego Princess on Vacation Isle in Mission Bay 10 minutes away from the San Diego International Airport. San Diego combines the proximity of Mexico with internationally famous landmarks including the San Diego Zoo Balboa Park Sea World Cabrillo National Monument Mission Bay Aquatic Park San Diego Harbor Old Town Wild Animal Park and Scripps Aquarium. Disneyland is only 90 miles to the north and Tijuana Mexico is approximately 30 miles to the south. The average high temperature in January is 65OF. A Conference social evening on January 13 will feature a dinner and show. Daily social hours and refreshments also are planned. Accommodations and Travel Central Travel Springfield Massachusetts is the official Conference travel agency. Accommodations at the San Diego Princess where all Conference activities will take place can be reserved with Central Travel at a special Conference rate of $92 per day (excluding tax) before October 15.After that a late fee will be charged. Arrangements for families with children are provided and extended stays before and after the Conference are offered at the Conference rate. Special low airfares and discount automobile rentals are available exclusively through Central Travel. For travel information and reservations contact Central Travel at 800-777-1 680 (US) or 41 3-781 -1 680; fax 41 3-737-9772. Registration The Conference registration fee indudes a copy of the Conference proceedings Conference abstracts and a souvenir tee shirt.The registration fee is $285 prior to October 15 $400 until December 20 and $475 thereafter. Discounts are provided for students and no registration fee is required for spouses. Short-course preregistration fee is $75 prior to October 15 $1 25 until December 20 and $175 afterward for each four- hour short course. For information concerning exhibition registration facilities and fees contact the Conference chairman. Advertising rates for the Conference program book also are available upon request. Call for Papers and Submission Schedule Titles and 50-word abstracts of papers describing original work with plasma spectrochemical applications fundamentals and novel instrument developments are solicited by July 3,1993. For accepted papers final abstracts are due by October 8,1993.Manuscripts for publication in the proceedings are requested by January 10,1994. For further information and registration materials contact 1994 Winter Conference on Plasma Spectrochemistry Attention Ramon Barnes Department of Chemistry 102 Lederle GRC Towers University of Massachusetts Amherst MA 01 003-0035 USA. (41 3) 545-2294 fax (413) 545-4490 e-mail RAMON.M.BARNESQCHEMISTRY.UMASS.EDU.r 3 STREEJ 4 TOWN 5 COUNTY POST CODE 6 COUNTRY 7 DEPARTMENT DIVISION 8 YOUR JOB TITLE POSITION 9 TELEPHONE NO I I I I I I I I s 1 - n 1 % I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Postage will be paid by Licensee Do not a Channel f i x Postage Stamps if posted in Gt. Britain slands N. Ireland or the Isle of Man BUSINESS REPLY SERVICE Licence No.WD 106 Reader Enquiry Service Journal of Analytical Atomic Spectrometry The Royal Society of Chemistry Burlington House Piccadilly LONDON W1E 6WF England I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I !r 3 STREEJ 4 TOWN 5 COUNTY POST CODE 6 COUNTRY 7 DEPARTMENT DIVISION 8 YOUR JOB TITLE POSITION 9 TELEPHONE NO I I I I I I I I s 1 - n 1 % I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Postage will be paid by Licensee Do not a Channel f i x Postage Stamps if posted in Gt.Britain slands N. Ireland or the Isle of Man BUSINESS REPLY SERVICE Licence No. WD 106 Reader Enquiry Service Journal of Analytical Atomic Spectrometry The Royal Society of Chemistry Burlington House Piccadilly LONDON W1E 6WF England I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I !r 3 STREEJ 4 TOWN 5 COUNTY POST CODE 6 COUNTRY 7 DEPARTMENT DIVISION 8 YOUR JOB TITLE POSITION 9 TELEPHONE NO I I I I I I I I s 1 - n 1 % I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Postage will be paid by Licensee Do not a Channel f i x Postage Stamps if posted in Gt. Britain slands N. Ireland or the Isle of Man BUSINESS REPLY SERVICE Licence No. WD 106 Reader Enquiry Service Journal of Analytical Atomic Spectrometry The Royal Society of Chemistry Burlington House Piccadilly LONDON W1E 6WF England I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I !

ISSN:0267-9477    

DOI:10.1039/JA99308BP043

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 45N Foreword 1993 European Winter Conference on Plasma Spectrochemistry Granada Spain January The fifth European Winter Conference on Plasma Spectrochemistry appears to have been well worth attending for participants coming to Granada and naturally well worth the effort for the organizers! Science was always pre- dominant in a fortunate encounter of a special location people and weather. This mixture seems to have produced a meeting to remember. After the meeting in Granada it can be assured that plasma spectrochemis- try continues to ‘excite’ the interest of the analytical community worldwide. In fact around 250 scientific delegates registered at the Conference from over 25 countries all around the world. Sessions were well attended which means that most delegates resisted strong temptations to view the city of Granada or to visit the ski resort in Sierra Nevada. New trends instru- mental developments and applications of analytical plasmas were addressed and freely discussed in the six plenary lectures ten key-note lectures thirty- four oral presentations and three poster sessions of 43 posters per ses- sion.It was in the second of the poster sessions while setting up his poster that Dr. Wojciech Vieth suffered a fatal heart attack and died on the way to the hospital. Our sincere regrets are expressed to his family. All the above numbers amount to around 170 scientific contributions from which the abstracts have ap- peared in the April issue of ICP Infor- mation Newsletter. These numbers are larger than those registered in previous European Winter Conferences.More- over they are approaching the presen- tation of 204 papers and the atten- dance of 450 delegates at the American sister meeting last year in San Diego.’ The most numerous national delega- tion came from Spain (nearly 60 dele- gates almost double the number of attendees coming from the second largest national delegation Germany). This is a matter of congratulation in a country whose economic power is not particularly well suited to implement relatively expensive plasma tech- niques as routine analytical tools. It seems that only 30 years after Stanley Greenfield and coworkers first demon- strated the usefulness of ICP for chemical analysis plasma spectros- copy has expanded from an esoteric 1045,1993 topic of a few convinced devotees from highly developed industrial countries to a routine analytical tool of great practical importance in analyt- ical problem solving almost ev- erywhere.Unfortunately there are still countries where this ‘plasma invasion’ is slow and even painful. After my previous contacts in Chile with presti- gious Latin American atomic spectros- copists we had greater hope that Gra- nada could become a first ‘pier of a necessary bridge’ (a nice image of Paul Boumans) for communication be- tween European and Latin American atomic spectroscopists. In spite of our efforts the economic crisis greatly hampered our initiatives as only a few delegates from Argentina Brazil and Chile finally attended the conference- Some hope came in Dr.Batistoni’s lecture when he said that ‘a growing interest in plasmas is envisaged in Latin America’; so it is hoped that the situation will improve in the near future. The technical content and develop- ment of the scientific programme have been discussed previously in detail by Dr. Garcia Alonso in his conference report.2 Therefore I would only remark here that perhaps the feature I noticed as most striking was how interest in basic research and development of single atomic detectors or even tan- dem sources is moving towards re- search on hybrid systems (e.g. chro- matography or flow injection-plasmas) to solve real problems (e.g. environ- mental and biological issues dealt with on the last two days of the conference) where more sensitivity (preconcentra- tions) more selectivity (matrix re- moval) or molecular information (spe- ciation) are urgently needed to expand the scope of plasmas.The three special sessions dedicated to current ‘hot plasma topics’ the seven short-courses presented by leading scientists and a successful instrument exhibition (where fifteen instrument manufacturers showed us their latest plasma products) completed the pic- ture of the scientific and technical side of the meeting. The 25 manuscripts published in this special issue give a good flavour of the scientific success of Granada’s meeting. The ‘other aspect’ of any scientific meeting which people deeply appreci- ate but are afraid to publicly confess to its importance turned out to be also most rewarding and enjoyable.The magical city of Granada had probably something to do with it; its beautifully preserved art and history (The Alham- bra The Generalife The Alcaiceria are ‘open books’ of the good old times of Granada) and the host of sights sounds and tastes which surround you in this unique city are difficult to forget. Moreover the gods of weather were clearly propitious because the whole week was blessed with an im- peccable sunny sky and pleasant tem- perature. Only if you add to all that atmosphere the recognized hospitality of the fun-loving southern Spanish people and the local flavour of the social evening events can you rational- ize the strange phenomena observed in some of those events (e.g. the striking sight of so many respectedreknowned international spectroscopists of all ages letting their hair down raising their arms and trying to emulate those beautiful Flamenco dancers of Mega Viajes and of the Conference after- dinner show!).Let me conclude by saying that the great interest and attendance demon- strated in Granada even in the middle of this economic crisis gives us the basis to continue celebrating the next meeting in the old Europe. The 1995 European Winter Conference is still in the process of being arranged and information on that meeting is ex- pected by the 1994 Winter Conference in San Diego USA. Finally I hope that our efforts in Spain to promote the active participa- tion from Latin American spectros- copists will continue to flourish on both sides of the Atlantic crossed for the first time five hundred years ago by a Spanish expedition commanded by Columbus (Cristobal Colon). Alfredo Sanz-Medel Conference Chairman University of Oviedo Oviedo Spain References 1 2 Barnes R. M. J. Anal. At. Spectrom. 1992 7 781. Garcia Alonso J.I. J. Anal. At. Spec- trom. 1993 8 27N.

ISSN:0267-9477    

DOI:10.1039/JA993080045N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

46N JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 Obituary Woiciech Vieth Dr. Woiciech Vieth died tragically and unexpectedly of a heart attack on Tuesday January 12 the second day of the ‘European Winter Conference on Plasma Spectrochemistry’ in Granada as he was preparing his poster for presentation in the early morning. First aid was immediately available and resuscitation was started in the hospital as soon as possible but any help was too late. His death was a big shock not only for all participants of the confer- ence and people who knew him but mainly for his family. He leaves behind his wife Elzbieta and their two children Piotr and Anna for whom his sudden death was a very big loss. The organizers of the conference and his friends did their very best to help his family in this tragic moment.Many problems were caused by the fact that he died in Spain but lived in the USA and kept his Polish citizen- ship. It took more than a week to overcome all these problems but fin- ally the funeral could take place in California his chosen home where his family is living. Woiciech Vieth was born on May 4 1947 in Radom Poland. He finished his studies at the university in 1970 as one of the best students of his course. In 1974 he started working as a senior engineer in the Structural Research Department at the Institute of Electronic Materials Technology in Warsaw on thermal analysis for appli- cation in metallographic and crystalli- zation processes. In 1976 he started lecturing as an Assistant Professor. In 1977 he became manager of the mass spectrometry laboratory in the analytical division of the institute where he came in contact with elemen- tal mass spectrometry for the first time.In this new field he gave proof of considerable talent by becoming an expert in spark source mass spectro- metry (SSMS) in a very short time as can be seen from a number of publica- tions and presentations at conferences in those times. Very soon his main interest was devoted to the develop- ment of procedures to improve sensi- tivity accuracy and precision in SSMS. With this primary aim he started to model processes taking place in the spark source plasma and in the ion beam of the mass spectrometer. The result of this study was the devel- opment of a model calculation which from a practical point of view could improve the accuracy by a factor of 3 at best.The results of these investiga- tions were the basis for a Ph.D. thesis in 1986. I first met him and his family in May 1987 when he became a guest co- worker of our institute engaged in a project for analytical characterization of pure metals. He was accompanied by his wife and his two children and my family and I immediately made friends with them and this was the beginning of an intense friendship. In the analytical research work being carried out in our group he soon found his second love in elemental MS glow discharge mass spectrome- try (GDMS). All his experience from SSMS could be utilized for this really promising and exciting technique and it took only a very short time before he was fully accepted as a member of our working group and had a strong influ- ence on our work in GDMS.His friendly character and his open- minded nature made this co-operation fruitful and pleasing for all persons involved and he became familiar as a scientist who worked with high moti- vation and concentration for improve- ment and promotion of this new ana- lytical technique. Again his main inter- est was to study the physical processes taking place in the glow discharge plasma with the aim of improving sensitivity and accuracy in GDMS on the basis of model calculations. It was one of his dreams to work and to live in the USA which was realized when in 1988 he was employed at Charles Evans and Associates in Redwood City CA because of his extraordinary knowledge and experi- ence in solid state mass spectrometry.Being engaged mainly in commercial analysis of different types of samples by GDMS he was successful in work- ing out new analytical procedures not only for conducting but also for semi- conducting and even for non-conduct- ing samples. His creativity contributed to continuous progress in elemental mass spectrometry expanding this technique to new applications. Al- though he had a full-time job in rou- tine analysis he nevertheless managed to produce publications covering fun- damental aspects of GDMS. At the end of his too short life a respectable scientific achievement is connected with his name. More than 20 publications with his authorship can be found in national and interna- tional journals of analytical chemistry. His presence and his contributions in national and international conferences will be greatly missed. His early passing is deeply regretted by his many professional and personal friends who sincerely condole with his family. Norbert Jakubowski Inst it u t f i r Spektrochem ie und angewandte Spektroskopie Dortmund Germany 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 WlV OBN UK. Tel +44 (0)71-437 8565; fax +44 (0)7 1-287 9798; Telecom Gold 84 BUR2 10 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.

ISSN:0267-9477    

DOI:10.1039/JA993080046N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 47N Diary of Conferences and Courses 1993 5th Beijing Conference and Exhibition on Instrumental Analysis October 11-16 Beijing China Details can be found in J. Anal At. Spectrom. 1992 7 39N. For further information contact The Secretariat of BCEIA Room 5412 Building 4 Xi Yuan Hotel 10046 Beijing P. R. China. Telephone 86 1 83 13388/5412; telex 20056 BCEIA CN; fax 86 1 8320908. 2nd National Conference on Inductively Coupled Plasma Mass Spectrometry October 16-17 Detroit MI USA For further information contact F. W. Kunz Ford Research Laboratory M/D 5-3061/SRL Room 1341 P.O. Box 2053 Dearborne MI 48121 USA. Telephone (3 13) 845-8536; fax (3 13) 323-7397. Society for Applied Spectroscopy Short Courses October 16-17 Detroit MI USA Fourier Transform Infrared Spectro- metry Plasma Spectrochemical Analysis Applied Near-infrared Spectroscopy Modem Analytical Spectroscopy Biological Infrared and Raman Spec- troscopy Modern Furnace Atomic Absorption For further information contact Society for Applied Spectroscopy 198 Thomas Johnson Drive S-2 Frederick MD 2 1702-43 17 USA.Telephone (3 10) 694-8 122. 20th Annual Meeting of the Federation of Analytical Chemistry and Spectro- scopy Societies (FACSS) October 17-22 Detroit MI USA For further information contact FACSS P.O. Box 78 Manhattan KS 66502-0003. Telephone 301 846 4797. Environmental Analysis and Assess- ment. A Series of Nine Short Courses Modules October 1993-March 1994 Details can be found in J. Anal. At. Spectrom. 1993 8 40N. For further information contact Im- perial College Continuing Education Centre Room 558 Sherfield Building South Kensington London UK SW7 2AZ.Telephone 071 225 8667; fax 071 225 8668. 3rd International Conference LASER M2P December 8-10 1993 Lyon France Details can be found in J. Anal. At. Spectrom. 1993 8 12N. For further information contact Centre Jacques Cartier Conference Laser M2P 86 rue Pasteur 69365 Lyon Cedex 07 France. Telephone (33) 78 69 72 21; fax (33) 78 61 07 71. 1994 WCFIA 94 1994 Winter Conference on Flow Injection Analysis January 5-7 1994 San Diego CA USA The Sixth Winter Conference on Flow Injection Analysis will be held on January 5-7 1994 at the San Diego Princess Convention Center followed by short courses highlighting special topics January 7-9 1994 in the follow- ing areas.WCFIA 94 will focus on industrial FIA and SIA techniques solving real world problems. New hardware and state of the art software-driven applications will be presented by leaders in the field. The three-day conference will high- light the following areas sequential injection analysis; process chemistry; industrial applications; biotechnology; instrument design; automation; new methods; atomic spectroscopy; and electrochemistry. Principles of Flow Injection Anal- ysis-Gil Pacey Miami University Oxford Ohio Sequential Injection Analysis-Jarda Ruzicka and Gary Christian Univer- sity of Washington Seattle Washing- ton Method Development/Optimization in FIA-Adrian Wade University of British Columbia Vancouver British Columbia Sampling Systems and Industrial Ap- plications of FIA-Don Olson FIA Solutions Houston Texas Detectors/Automation in FIA-Sandy Dasgupta Texas Tech University Lubbock Texas FIA in Atomic Absorption Spectro- scopy-Julian Tyson University of Massachusetts Amherst Massa- chusetts Electrochemical Methods and Sensors in FIA-Ari Ivaska Abo Akademi University; Turku-Abo Finland; and Joe Wang New Mexico State Univer- sity Las Cruces New Mexico Chromatography for FIA Practition- ers-John Dorsey University of Cin- cinnati Cincinnati Ohio Titles for lecture or poster papers are solicited by October 15 1993.Ab- stracts are requested by November 15 1993. Registration by October 15 1993 (Regular $225 Student $100 and on-site registration $275). For further information contact WCFIA 94 Gary Christian Depart- ment of Chemistry BG- 10 University of Washington Seattle WA 98195.Telephone (206) 543-1635; fax (206) 685-3478; e-mail christia@ chem.- washington.edu. 1994 Winter Conference on Plasma Spectroc hemis try January 10-15 1994 San Diego CA USA Details can be found in J. Anal. At. Spectrom. 1992 7 49N. For further information contact Dr R. M. Barnes 1994 Winter Conference on Plasma Spectrochemistry c/o ICP I n formation Newsletter Department of Chemistry GRC Towers Univer- sity of Massachusetts Amherst MA 01 003-0035 USA. Telephone 4 13 545 2294; fax 413 545 4490. 45th Pittsburgh Conference and Expo- sition on Analytical Chemistry and Applied Spectroscopy48N JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 February 28-March 4 Chicago IL USA For further information contact Pittsburgh Conference 300 Penn Center Boulevard Suite 332 Pitts- burgh PA 15235-9962 USA.ANATECH 94 4th International Sym- posium on Analytical Techniques for Industrial Process Control April 10-13 1994 Royal Hotel Casino Mandelieu La Napoule France Venue The symposium will be held at the Royal Hotel Casino Mandelieu La Napoule France. Within easy reach of Nice-CBte d’Azur and Cannes- Mandelieu airports the hotel offers luxury accommodation overlooking the sea or the golf course. With tennis court swimming pool health centre and its own casino it provides an ideal opportunity to enjoy the CBte d’Azur at its best. Call for Papers Authors are requested to submit two copies of abstracts in English typed in double spacing not exceeding 300 words including title name(s) or author(s) and affiliation.Both copies should be sent to ANATECH 94 Secretariat Elsevier Advanced Tech- nology Mayfield House 256 Banbury Rd Oxford UK OX2 7DH. Please ensure that the full address including country of origin is clearly stated and indicate whether an oral paper or a poster will be presented. Each abstract should include the following signed statement ‘Neither this paper not any version close to it has beenlis being offered elsewhere for publication and if accepted the paper will be personally presented at ANA- TECH 94 by the author or one of the co-authors.’ Deadline for submission of abstracts is August 31 1993. The official language of the conference will be English. Exhibition An exhibition will be arranged in conjunction with the conference.Registration As with previous ANATECH meet- ings an all-inclusive package is offered which covers the registration fee all accommodation and meals a welcome reception banquet and a copy of the proceedings. Full details will be given in the next announcement. For further information contact ANATECH 94 Secretariat Elsevier Advanced Technology Mayfield House 256 Banbury Road Oxford UK OX2 7DH. Telephone +44 (0) 865 512242; fax +44 (0) 865 310981. 24th Annual Symposium on Environ- mental Analytical Chemistry May 16-19,1994 Ottawa Canada For further information contact M. Malaiyandi CAEC Chemistry De- partment Carleton University 1255 Colonel By Drive Ottawa Ontario Canada. International Symposium on Micro- chemical Techniques (ISM ’94) May 16-20 Montreux Switzerland The International Symposium on Microchemical Techniques (ISM ’94) will have its next meeting in a joint organization with the Deanville Con- ference 1994-Symposium on Analyt- ical Sciences (SAS ’94) in Montreux Switzerland from May 16-20 1994.For further information contact Nicko & C.R.I. Associes 7 Rue d’Argout F-75002 Paris France. Telephone + 33-1 -42 334766; fax +33-1-40 41 92 41.. Scandinavian Symposium on Infrared and Raman Spectroscopy SSIR-94 May 30-June 1 1994 Department of Chemistry University of Bergen N-5007 Bergen Norway The First Scandinavian Symposium on Infrared/Raman Spectroscopy will take place during May 30-June 1 1994 at the University of Bergen Norway covering all fundamental as- pects instrumental developments and applications in (mid and near) infra- red/Raman spectroscopy and new sampling techniques such as diffuse reflectance internal and external reflectance specular reflectance photo-accoustic etc.The symposium will also cover hyphenated techniques such as GC-IR LC-IR GUMS-IR SFC-IR and infrared microspectro- scopy. Spectral interpretation and neural networks and chemometric techniques in spectral data handling and interpretation are also subjects of interest. Venue The symposium will take place at the Science building of the University of Bergen. May/June is an ideal time to visit and enjoy the beautiful surround- ings of the symposium venue. Bergen can be reached by air from all over the world. Car ferries from Denmark England and The Netherlands are other alternatives.There is a scenic high mountain rail-road from Oslo. Scientific Programme The scientific programme involves in- vited lectures keynote lectures and contributed papers (oral and posters). The Symposium language is English. Invited Lecturers Professor Peter R. Griffiths Univer- sity of Idaho Idaho USA Professor P. Hendra University of Southampton UK Professor Peter Klieboe University of Oslo Norway Professor John van der Maas Univer- sity of Utrecht The Netherlands Dr. Tormod Nzs Matforsk Oslo Norway Call for Papers Participants wishing to present a paper should submit a camera-ready copy of an abstract (not exceeding an A4 size page) before 15 December 1993. The authors will be informed by 15 Janu- ary 1994 about acceptance.Social Programme The social programme includes a wel- come party and a Symposium dinner. Tours will be arranged for the partici- pants and accompanying persons. More details will follow in the second announcement. Exhibition If there is sufficient interest an Exhibi- tion of instruments will be organized during the Symposium. Those who are interested in exhibiting their instru- ments should contact Dr. Alfred A. Christy for details. For further information contact Dr. Alfred A. Christy Department of Chemistry University of Bergen. Tele- phone +47 5-2 13363 (after 09.09.93) +47-55-213363); fax +47-5-329058 (after 09.09.93) +47-55-329058). Laila Kyrkjebo Department of Chemistry University of Bergen telephone + 47-5-2 13342 (after 09.09.93 +47-55-2 13342). Biosensors ’94 The Third World Con- gress on BiosensorsJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL.8 49N June 1-3 New Orleans LA USA Details can be found in J. Anal. At. Spectrom. 1993 8 42N. For further information contact Kay Russell Conference Department Elsevier Advanced Technology May- field House 256 Banbury Road Oxford UK OX2 7DH. Telephone +44 (0) 865 512242; fax +44 (0) 865 3 1098 1. 6th International Conference on Flow Analysis June 8-11 Toledo Spain Details can be found in J. Anal. At. Spectrom. 1993 8 42N. For further information contact M. ValcarceVM. D. Luque de Castro Flow Analysis VI Departamento de Quimica Analitica Facultad de Cien- cias E- 14004 Cordoba Spain. Tele- phone 34 57 218616; fax 34 57 2 18606. 7th International Symposium on Reso- nance Ionization Spectroscopy and Its Applications (RIS-94) Bernkastel-Kues Germany The Seventh International Symposium on Resonance Ionization Spectroscopy and Its Applications (RIS-94) is organ- ized by the International Advisory Committee and the Local Organising Committee from the University of Mainz and the GSI Darmstadt.The meeting will be held in a modem con- ference hotel complex (Hotel Mosel- park) in the medieval Moselle wine village of Bemkastel-Kues Germany from July 3-8 1994. On July 3 a one- day introductory course on RIS physics is planned for students in particular. The conference site is easily reached by rail road and by air via Frankfurt Luxembourg or Cologne airports. Symposium topics will include the theory of light matter interaction; pic0 and femtosecond spectroscopy; atomic ionization spectroscopy; molecular ionization spectroscopy; analytical and environmental applications; ultra- sensitive methods; nuclear applica- tions; surface and bulk analysis; chemical applications; biological and medical applications; atomic molecu- lar and ion sources; laser sources; and new techniques and exotic applica- tions.July 3-8 1994 For further information contact RIS-94 R. Chitty Institut fur Physik Universitat Mainz Postfach 39 80 D- 55092 Mainz Germany telephone 0049-6 13 1-393628; fax 0049-6 13 1- 393428; telex 418-7155 phmz d; email RIS94@VIPMZA.PHYSIK. UNI-MAINZ.DE. Seventh Biennial National Atomic Spectroscopy Symposium University of Hull Hull UK Details can be found in J. Anal. At. Spectrom.1992 7 49N. For further information contact Dr Steve Hill Department of Environ- mental Sciences University of Plymouth Drake Circus Plymouth Devon UK PL4 8AA. July 20-22,1994 13th International Mass Spectrometry Conference August 29-September 2 Budapest Hungary For further information contact Hun- garian Chemical Society; FO u. 68 H- 1027 Budapest Hungary. Telephone 361 201 6883; fax 316 15 61215. EUCMOS XXII XXII European Con- gress on Molecular Spectroscopy September 11-16 1994 Essen Germany The congress will cover all methods and applications of molecular spec- troscopy from theory to problem solving. Its purpose is to catalyse inter- national co-operation and exchange of ideas. Plenary lectures will deal with new developments and topics of gen- eral interest.Poster sessions and work- shops with contributed papers provide the opportunity to present and discuss new results. EUCMOS XXII is especially inten- ded to help colleagues from Eastern Europe to establish new contacts. Lim- ited funds are available for those who contribute a poster or paper. Details for application will be given in the Second Circular. Key Topics Industrial medical and environmen- tal problems; sensors remote spectro- scopy astrophysics; molecular elec- tronics semi- and superconductors; solid state effects of phase order temperature pressure; space resolu- tion surfaces nanostructures micro- scopy mapping tomography; time resolution transients relaxation; reso- nance and non-linear phenomena; biomolecules chirality; structure in- teraction modelling; and new tech- niques. Exhibition In the lobby of the Congress Centre Ost new instruments will be demon- strated.Interested exhibitors are re- quested to contact the secretariat. Examples of problem solving in industry medicine and ecology will be demonstrated by firms and research organizations. A Market for Problems will be established for discussions about unsolved problems and to pro- mote cooperation leading to their solution. Further Circulars The Second Circular and Call for Papers will be mailed in summer 1993. For further details contact Gesell- schaft Deutscher Chemiker Abt. Tagungen P.O. Box 90 04 40 W-6000 Frankfurt 90 Germany. Telephone +49 697917-366; fax +49 69 7917- 475; telex 4 170 497 gdch d. Geoanalysis 94 An International Sym- posium on the Analysis of Geological and Environmental Materials September 18-22,1994 Charlotte Mason Conference Centre Am bleside UK.Geoanalysis 94 will be an Interna- tional Symposium covering all aspects of the analysis of geological and envi- ronmental samples and is designed to attract international participation from scientists in Universities Re- search Institutes Commercial and In- dustrial Laboratories interested in any aspect of developments in analytical geochemistry. The scope of the sympo- sium includes advances in bulk and microprobe analytical techniques (whether elemental or isotopic for solids or fluids) reference materials and data quality. It is planned that sessions will be organized to cover the applications of geoanalysis in both geochemical research and environ- mental assessment.In addition con- tributions will be particularly welcome on the themes of field sampling and measurement quality control and laboratory accreditation reference materials for microanalysis develop- ments in techniques for isotopic anal- ysis and geoanalytical techniques used in environmental applications. Venue The Charlotte Mason Conference Centre in Ambleside lies in the heart of the English Lake District near to the shores of Lake Windermere. The pur- pose-built conference facilities offer both luxury bedrooms and more eco- nomical accommodation on site all50N JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 within easy walking distance of lecture theatres dining areas and sports facili- ties. The nearest International airport is at Manchester and there are excel- lent travel links by road (M6 motor- way) or rail (West Cost Main line to Oxenholme).Dates to Note Second Circular available October 1993. Final Circular and application forms available January 1994. Dead- line for the submission of abstracts 3 1 March 1994. Deadline for registration at the discounted rate 30 June 1994. Workshop/Field Trips A number of pre- and post-symposium workshops and field trips designed in part to be of a tutorial nature and to cover specific aspects of geoanalysis are being planned. These events will be organized according to demand. Representative Sampling of the Lake District Province a workshop to ad- vance ideas in sampling coupled to a field excursion to selected localities in the Lake District to apply these con- cepts.Quality Assurance and Laboratory Ac- creditation a workshop to discuss concepts and issues followed by a visit to selected commercial and research geoanalytical laboratories to see how these procedures are implemented. Reference Materials Preparation and Analysis a workshop followed by a field excursion to collect and plan the characterisation of a new candidate reference material. Statistics and Reference Material Data Sets a workshop for logical statisti- cians on the one hand and pragmatic empiricalists on the other to put their cases with a view to reaching a concen- sus. Environmental Effect of Mining in the Lake District a field trip to evaluate the role of sampling and analysis in assessing the environmental impact of disused mines in a National Park which is a designated area of outstand- ing beauty.Sellafield a visit to the nuclear repro- cessing centre. Social Programme It is planned that an accompanying persons programme will be available to allow visitors to view the spectacu- lar Lake District scenery and to visit places of interest associated with some of the famous inhabitants of the area including William Wordsworth John Ruskin and Beatrix Potter. Multilin- gual tutors with expertise in these literary areas can lead these tours if the demand is sufficient. For further information contact Mr. D. L. Miles Analytical Geochemistry Group British Geological Survey Kingsley Dunham Centre Keyworth UK NG12 5GG. Telephone 0602 363100; fax 0602 363200. 7th International Symposium on Envi- ronmental Radiochemical Analysis September 2 1-23 Bournemouth UK Dates to Note Synopses of papers January 28 1994.Final date for registration July 15 1994. For further details contact Dr P. Warwick Department of Chemistry Loughborough University of Tech- nology Loughborough Leicestershire UK LEll 3TU. Telephone 0509 222585 or 0509 2:22545; fax 0509 233 163. 1995 Colloquium Spectroscopicum Interna- tionale (CSI) XXIX August 27-September 1 1995 Leipzig Germany Venue The CSI will be held mainly in the University which is situated in the centre of Leipzig. Therefore you can visit all historical places and take part in the life in the centre. Leipzig is located in Saxonia and is easily reached by train car and aircraft. Scientific Programme Atomic absorption spectrometry atomic emission spectrometry atomic fluorescence spectrometry gamma spectrometry laser spectroscopy mass spectrometry molecular spectroscopy and X-ray and electron spectroscopy.Theoretical advances experimental developments and applications for bulk analysis distribution analysis local analysis microanalysis structure analysis surface analysis and trace analysis. Special topics include all sam- ple introduction techniques automati- zation and computerization tandem techniques for speciation analysis e.g. chromatography element detection and quality assurance in analysis. Application fields include agriculture biology chemistry environment food geology health hydrology metallurgy and research and industrial aspects instruments books chemicals and standards. Exhibitions will be orga- nized for several topics. For further details contact Prof. Dr. K. Dittrich Universitat Leipzig FB Chemie FG Atomspektroskopie Lin- nestr.3 D-04 103 Leipzig Germany. Telephone and fax (49)-341-6858377. UFZ-Centre for Environmental Re- search Department of Analytical Chemistry Permoserstr. 15 D-043 18 Leipzig Germany. Telephone (49)- 341-235-2370; fax -2625.

ISSN:0267-9477    

DOI:10.1039/JA993080047N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

50N JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 Future Issues will Include Operation Principles and Design Atomization Non-thermal Excitation and Urine by Zeeman-effect Electro- Considerations for Radiofrequency Spectrometry-Philip G. Riby and thermal Atomic Absorption Spectro- Powered Glow Discharge Devices- James M. Harnly. metry-Jane K. Johannessen Bente Kenneth R. Marcus. Gammelgaard Ole J h s and Steen H. Comparison of Chemical Modifiers for €bsen Characterization of a Helium Dis- Simultaneous Determination of Dif- charge for Hollow Anode Furnace ferent Selenium Compounds in Serum Use of the Hildebrand Grid NebulizerJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 51N as a Sample Introduction System for Microwave-induced Plasma Spectro- metry-Henryk Matusiewicz.Diagnostic Investigations of Aerosols With Varying Water Content in Induc- tively Coupled Plasma Mass Spectro- metry-Norbert Jakubowski Ingo Feldmann and Dietmar Stuewer Evaluation of Linear Photodiode Array Detection for Continuum Source Atomic Absorption Spectro- metry With Electrothermal Atomiza- tion-Clare M. M. Smith Robbin Nichol and David Littlejohn In Situ Concentration of Selenium and Tellurium Hydrides in a Silver-coated Graphite Atomizer-Zhe-Ming Ni Bin He and Heng-bin Han Determination of Traces of Lutetium in Geological Samples by Resonance Ionization Spectrometry-T. B. Krus- tev S. T. Mincheva D. A. Angelov and E. P. Vidolova-Angelova Determination of Lead by Electrother- mal Vaporization Microwave-induced Plasma Atomic Emission Spectro- metry After Flow-through Electrolytic Deposition in a Graphite Tube Packed With Reticulated Vitreous Carbon -Ernest Beinrohr Ewa Bulska P.Tschopel and G. T61g A Study of X-ray Fluorescence Spec- trometry and Spark Ablation In- ductively Coupled Plasma Atomic Emission Spectrometry for Chromium Determination in Ferrochromium From Bulk Metal Samples-Aurora G. Coedo Teresa Dorado Carlos J. Riv- ero and Isabel G. Cob0 Isotope Ratios of Calcium Determined in Calcium-46 Enriched Samples From Infants by Automated Multiple- collector Thermal Ionization Mass Spectrometry-Judith R. Turnlund William R. Keyes Karen C. Scott and Richard A. Ehrenkranz Immobilized Cysteine as a Reagent for Preconcentration of Trace Metals Prior to Determination by Atomic Absorption Spect rometry-Hayat A.M. Elmahadi and Gillian M. Greenway Determination of Trace Metals in Concentrated Brines Using Induc- tively Coupled Plasma Mass Spectro- metry On-line Preconcentration and Matrix Elimination With Flow Injec- tion-Les Ebdon Andrew Fisher Howard Handley and Philip Jones Determination of Gold by Slurry Graphite Furnace Atomic Absorption Spectrometry After Preconcentration by Escherichia Coli and Pseudomonas Putida-L. C. Robles C. Garcia-Olalla and A. J. Aller Isotope Ratio Measurement by Induc- tively Coupled Plasma Multiple Collector Mass Spectrometry Incorpo- rating a High Efficiency Nebulization System-Andrew J. Walder Dagmar Koller Nicola M. Reed Robert C. Hutton and Philip A. Freedman Mineralization of Biological Materials Prior to Determination of Total Mer- cury by Cold Vapour Atomic Absorp- tion Spectrometry-Jorge E.Tahan Victor A. Granadillo Jose M. Sanchez Hernan S. Cubillan and Romer A. RomeroRamon M. Barnes Editor Department of Chemistry LGRC Towers University of Massachusetts Am herst MA 01 003-0035 Telephone (413) 545-2294 fax 545-4490 Objective The ICP INFORMAT/ON NEWSLETTER is a monthly journal published by the Plasma Research Group at the University of Massachusetts and is devoted exclusively to the rapid and impartial dissemination of news and literature information re- lated to the development and applications of plasma sources for spectrochemical analysis. Background ICP stands for inductively coupled plasma discharge which duringthe past decade has become the leading spectrochemi- cal excitation source for atomic emission spectroscopy.ICP discharges also are applied commercially as an ion source for mass spectrometry and as an atom and ion cell in atomic fluo- rescence spectrometry. The popularity of this source and the need to collect in a single literature reference all of the pertinent data on ICP stimulated the publication of the ICP INFOR- MATION NEWSLETTER in 1975. Other popular plasma sources i.e. microwave induced plasmas direct current plasmas and glow discharges also are included in the scope of the ICP IN- FO RMA TI0 N NEWSLETTER. Scope As the only authoritative monthly journal of its type the ICP INFORMATION NEWSLETTER is read in more than 40 coun- tries by scientists actively applying or planning to use the ICP or other types of plasma spectroscopy.For the novice in the field the ICP INFORMATION NEWSLETTER provides a concise and systematic source of information and background material needed forthe selection of instrumentation or the development of methodology. For the experienced scientist i t offers a sin- gle-source reference to current developments and literature. Editorial The ICP INFORMATION NEWSLETTER is edited by Dr. Ramon M Barnes Professor of Chemistry University of Mas- sachusetts at Amherst with the assistance of a 20-member Board of National Correspondents composed of leading plasma spectroscopists. The Board members from around the world report news viewpoints and developments. Dr. Barnes has been conducting plasma research on ICP and other dis- charges since 1968.He also serves as chairman of the Winter Conference on Plasma Spectrochernistry sponsored by the ICP INFORMATION NEWSLETTER. Regular Features .Original submitted and invited research articles by ICP and *Complete bibliography of all major ICP publications. eAbstracts of all ICP papers presented at major US and inter- .First-hand accounts of world-wide ICP developments. especial reports on dcp microwave glow discharge and other *Calendar and advanced programs of plasma meetings. *Technical translations and reprints of critical foreign-lan- guage ICP papers. *Critical reviews of plasma-related books and software. Conference Activities The ICP INFORMATION NEWSLETTER has sponsored seven international meetings on developments in atomic plasma spectrochemical analysis since 1980 in San Juan Orlando San Diego St.Petersburg and Kailua-Kona. Meeting pro- ceedings have appeared as Developments in Atomic Plasma Specfrochemical Analysis (Wiley) Plasma Spectrochemistry ,and Plasma Spectrochemistry 11-IV (Pergamon Press) as well as in special issues of Spectrochimica Acta Part 5 and Journal of Analytical Atomic Spectrometry. The 1994 Winter Confer- ence on Plasma Spectrochemistry will be held in San Diego California January 10 - 15 1994; its proceedings will be published by Fall 1994. Subscription Information Subscriptions are available for 12 issues on either an annual or volume basis. The first issue of each volume begins in June and the last issue is published in May. For example Volume 18 runsfrom June 1992 through May 1993.Back issues beginning with Volume 1 May 1975 also are available. To begin a subscription complete the form below and submit i t with prepayment or purchase information. For additional informa- tion please call (41 3) 545-2294 fax (41 3) 545-4490 or contact the Editor. Credit cards accepted. plasma experts. national meetings. plasma progress. To order complete this section and send it to ICP Information Newsletter %Dr. Ramon M. Barnes Depart- ment of Chemistry Lederle GRC Towers University of Massachusetts Amherst MA 01 003-0035 USA. Start a subscription for the following issue 0 Volume(s)- (June 19- - May 19- ) or 0 19 (January - December). Enclosed 0 Prepayment 0 Check or money order OVISA 0 Mastercard Account No. (All 13 or 16 digits) ) or 0 Send invoice. Date M a i l to tl Purchase order (No. Card holder Name Expiration date - Cardholder Signature . Amount Due $ - Name Organization City State/Country ZI P/Pos talcode Note For each credit-card transaction a 4 % service charge willbe added reflecting our bank charges. Current subscription rates are $60 (North America) $85 (Europe South America) or $94 (Africa Asia Indian/Pacific Ocean Areas Middfe East and Russia). Back issue rates available on request. All payments should be made with US dollars by draft on a US bank by international money order or by credit card. Foreign bank checks are not accepted. Telephone Telex/f ax --

ISSN:0267-9477    

DOI:10.1039/JA993080050N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 767 Developments and Trends in Plasma Spectrochemistry-A View* Plenary Lecture Paul Boumans c/o Philips Research Laboratories WB7 P. 0. Box 80.000 5600 JA Eindhoven The Netherlands A review of the history of spectrochemistry over the past 40 years is taken as a starting-point for presenting a personal view on recent developments and current trends in plasma spectrochemistry . Booms and trends featured in graphical form are introductorily discussed. In that context an iconographic approach for the visualization of ratings of analysis methods is proposed. The main body of the discussion deals with assessments of the present position and future perspectives of furnace atomization plasma emission spectrometry plasma source mass spectrometry plasma source emission spectrometry and as a perhaps curious intruder and possibly serious competitor total-reflection X-ray fluorescence spectrometry.The potentials of recently introduced echelle array spectrometers for plasma source emission spectrometry are considered in the light of new or improved insights into the spectroscopic methodology and in the scope of input from developments in chemometrics. The paper is concluded with a brief review of the plasma spectrochemistry conferences in the past 18 years and their role for communication. Keywords Plasma spectrochemistry; graphite furnace plasma emission spectrometry; plasma source atomic emission spectrometry; plasma source mass spectrometry; X-ray fluorescence spectrometry Probably the term ‘Plasma Spectrochemistry’ appeared for the first time as the title of the Proceedings of the 1982 Winter Conference in 0rlando.l It followed the designation ‘Atomic Plasma Spectrochemical Analysis’ used in connec- tion with the first international Winter Conference held in San Juan de Puerto Rico in 1980.* The keyword in these expressions is ‘plasma’ an abbreviation of ‘plasma source’ a term which was introduced in the 1960s and has remained in use as a magic winged word up to the present day.The introduction of plasma sources in the 1960s marked the renaissance of atomic emission spectroscopy (AES).3 The term ‘plasma sources’ must then have been coined to show the analytical world that AES had rejuvenated itself by the invention and exploration of novel excitation sources whose capabilities were argued to extend far beyond the domains of arcs and sparks i.e.sources that the ‘parvenu’ of the 196Os atomic absorption spectroscopy (AAS) had marked out as old-fashioned and incapable. It therefore seemed psychologically better not to tell the AAS commu- nity that arcs and sparks were also ‘plasmas’ fundamentally not different from the new ‘plasma sources’ but to indoctrinate them with panegyrics singing the unique features of these ‘plasma sources’ a high temperature and an ability to accept aerosols of solutions in much the same way as combustion flames did. What is in a name if it can adequately serve as a battle-cry on the banners of crusaders who believed in their cause and made efforts to convince the community that ‘Plasma Spectrochemistry’ had to be identified with innovation and renovation? The belief and conviction of the crusaders and all their followers have in fact reshaped analysis in many respects including the extension of the umbrella ‘Plasma Spectrochemistry’ to cover also plasma source mass spectrometry (MS) glow discharge (GD) optical and mass spectrometry as well as particular areas of laser spectroscopy.It may be not only tempting but also inspiring to look at the past and to analyse and assess some developments in order to under- stand the present better and to extrapolate to the future. I will attempt to do this more or less under the motto ‘Plasma Spectrochemistry in search of innovation or ~~~ ~ *Presented in part as a Plenary Lecture at the opening of the 1993 European Winter Conference on Plasma Spectrochemistry Granada Spain January 10- 15 1993.confirmation?’ In that context I shall also pay attention to the communicative role of the Plasma Spectrochemistry Conferences in the United States and Europe including the European Plasma Spectrochemistry Conferences avant la lettre known as the ‘Noordwijk ICP Conferences’ (1 976 1 978).4*5 My intention is to present a view based on the insights I have gained during the nearly 40 years that I have been closely connected with analytical atomic spectrometry. The reader should thus not expect a review in which every statement is documented by references. Their number will be limited partly because an overdose of them would 1950 1960 1970 1980 1990 Year Fig.1 Characterization of the history of spectrochemistry in terms of ‘booms and trends’. The ordinate of each ‘whale’ depicts the ‘attention’ the relevant method received in the course of time whereby ‘attention’ should be understood to comprise research development and application. The scale is relative ‘within’ each method but does not include relative weights for the various methods. Acronyms are explained in Table 1768 Analytical and economic criteria chec klis f 0 Precision Accuracy Detection power Traces Minor/major 0 Solids metals 0 Solids non-conducting Liquids 0 Multi-element Selectivity Cornplexity/cost 0 Automation /cost JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 Table 1 Glossary of acronyms Table 2 Possible motives behind developments AAS AES A1 CCD CCP CID CMP DCP DSI ED ETV FANES FAPES FIA GC GD GF GIXA HA HC ICP LA LC MIP MS R.f.RSD RSDB RSDN SBR SNR TXRF WD XRFS Atomic absorption spectrometry Atomic emission spectrometry Artificial intelligence Charge coupled device Capacitively coupled plasma Charge injection device Capacitively coupled microwave plasma Direct current plasma Direct sample insertion Energy dispersive Electrothermal vaporization Furnace atomization non-thermal emission Furnace atomization plasma emission Flow injection analysis Gas chromatography Glow discharge Graphite furnace Glancing incidence X-ray analysis Hollow anode Hollow cathode Inductively coupled plasma Laser ablation Liquid chromatography Microwave-induced plasma Mass spectrometry Radiofrequency Relative standard deviation Relative standard deviation of the background Relative standard deviation of the net line signal Signal-to-background ratio Signal-to-noise ratio Total-reflection X-ray fluorescence spectrometry Wavelength dispersive X-ray fluorescence spectrometry spectrometry spectrometry detract from the view character of this paper but chiefly because it is impossible to retrace the roads that led to particular insights.Booms and Trends in Spectrochemistry a Brief Characterization Fig. 1 characterizes the history of spectrochemistry over the past 40 years. The acronyms used in this figure or elsewhere in the text are explained in Table 1. The picture shows a series of ‘whales’ representing the booms and trends on a relative scale for each method separately but does not cover the relative weights of the various methods.The diagram is approximate only and represents simply what I have in mind. The most important features are in the upper two-thirds of the diagram from XRFS-TXRF upwards. The trends of GFAAS-GFAES XRFS-TXRF plasma MS and plasma AES will be further discussed below. It may be interesting not only to consider the develop- ments themselves (Fig. l) but to look also briefly at the motives that have possibly driven these developments (Table 2). I leave it to analysts of human behaviour to make a balanced assessment but believe that the first four points stated in the table are the truly driving forces behind innovation. Why were scientists such as Greenfield Fassel Robin Mermet Ohls and I for example pioneers in the early years of the ICP? Because we believed in multi- element emission spectroscopy as a viable and indispen- sable analytical tool and also because we wished to avenge what we thought to be the initial cheap successes of the poor man’s spectroscopy of the 1960s atomic absorption! The reasons for these successes are clear (Table 3) which is why it was difficult to convince the man in the street that Urge to creativity Scientific ambition/competition Belief and conviction Challenges and dreams Social andor industrial needs Instrument markets Entrepreneurial making money Supply and demand Table 3 Reasons for initial success of flame AAS Direct anaiysis of liquids Analysis of dissolved solids (= isoformation) Many elements but typically one at a time Acceptable precision and accuracy Tailored to the minds and hands of wet chemists (sample treatment no problem!) Cheap and simple Spectroscopy of the ‘minute man’! Fig.2 Checklist with the most important features to be consi- dered in assessments of analysis methods there were better things to come! Admittedly the field of AAS has also seen radiant developments and has its enthusiastic and prominent pioneers such as Walsh Willis L’vov Slavin and others who believed in their causes and justly so! Much of the beliefs of both groups of missionaries the ‘emissionaries’ and the ‘absorptionists’ have been translated into hardware and software that now populate numerous laboratories. The first commercial ICP emission spectrometers became available in the mid-l970s resulting in the gradual accep- tance of the ICP as an analytical tool for the reasons shown in Table 4.Note in particular the last point which indicates that the emancipation of the wet analytical chemist has been an important factor! Assessing the Merits and Capabilities of Analytical Methods Generally speaking we may assess analytical methods with the aid of checklists of factors of the type shown in Fig. 2. Essentially these factors can be classified into two groups depending on whether they are connected with the sample or the method (Table 5). However this issue may also be approached in a modern graphical way using multivariate,JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 769 Table 4 Reasons for gradual acceptance of ICP-AES Analysis of liquids and dissolved solids Acceptable precision Simultaneous multi-element analysis Accuracy low multiplicative matrix effects Economy sample treatment for ICP far easier than for AAS Cost and complexity of AAS apparatus rose Emancipation of the wet ‘minute man’! Table 5 Sample-related and method-related criteria for assessing analytical methods Sample- Solid versus liquid Conducting versus non-conducting Trace versus minor versus major Detection power-range-selectivity Accuracy-precision Complexity-required expertise-cost Method- Maximum Minimum (a ) B Cost effectiveness I I Analytical figures of merit r\ Simplicity 0 0 00 A 0 Universality (sample types) Overall (zJ@ maximum Overall minimum Fig.3 Multivariate iconographic rating of analysis methods. (a) Icons representing four essential criteria to which the most important features of analysis methods can be reduced.The picture shows the maximum and minimum ‘values’ of the icons whereby ‘maximum’ refers to ‘best case’ and ‘minimum’ to ‘worst case’. (b) Assemblage of the icons into faces depicting the overall maximum and minimum ratings of an analysis method iconographic in which all factors are condensed to four essential features each represented by an icon with a minimum and a maximum [Fig. 3(a)]. A sophisticated computer program enables the user to assemble the icons into a four-dimensional picture as illustrated in Fig. 3 (b) which depicts the two extremes only. The power of the program is that it not only fits the correct face to the input data but can also provide a picture of the fate of a new analysis method as shown in Fig.4 whereby further icons are automatically added as new dimensions if the built-in artificial intelligence feels that the overall assessment should be enhanced. The program includes an automatic ‘bias protection feature’ in that the one-sided champion’s view is always supplemented by that of the adversaries. This approach will thus put a new analysis method always in the right perspective. Alluding to the above multivariate iconographic rating of analysis methods was not just for fun and entertainment only. In fact I did so as an introduction to an intriguing question about the reasons behind research projects. Fate of an analysis mefbod faced in phases and faces Actual finally lnit ia I Actual R expectation upon release Champions’ view @ 0 W Adversaries‘ view @ c~ 8 Fig.4 Fate of an analysis method faced in phases and faces Fig. 5 Causal relationships and chronology of the booms and trends in spectrochemistry. Arrows and connecting lines give a qualitative indication of the relationships and simultaneously the chronology. The diagram includes some diversifications within the scope of ‘methods’. Acronyms are explained in Table I Why are solutions often being sought to problems that others claimed to have solved 10 or 20 years ago using the same method or appear to have (better?) solved by other methods? Possible reasons are the following (1) Unawareness of existing solutions (2) No concrete evidence claimed solutions being (3) Context limitation claimed solutions being satis- (4) Redefined requirements extension of analytical (5) Technological innovation prompts. valid only ‘in principle’.factory only in a particular environment. capabilities or cost reduction needed. Apart from the trivial yet persistent unawareness of existing solutions ( l ) there are valid practical reasons (2-4) to embark upon research that confirms or extends the outcomes of earlier work while instigation by technological innovation (5) is doubtless a most laudable incentive. Below I shall point out a few developments in which innovation prompts have played a major role.770 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 l:i I 0 HC-FANES FAPES 0 Grimm 0 Boosted 0 Jet- enhanced Fig. 6 Block diagram of Fig. 5 stripped of items that have at present lost much of their attraction and topicality.The stripping covers both entire methods (‘defunct whales’ in Fig. 1) and diversifications (Fig. 5) that have flopped or turned out to be less world shocking than originally anticipated Booms and Trends in Blocks and Boxes It may be instructive to discuss current developments against the background of a self-explanatory block diagram (Fig. 5) that reveals simultaneously the causal relationships in and the chronology of the booms and trends in spectrochemistry. Obviously the parallelism between chro- nology and causal relationships is not at all surprising. In contrast what is surprising is what remains of the block diagram if it is stripped of the items that have lost all or most of their attraction and novelty as shown in Fig. 6.Only a few methods are seen to be really defunct most of them being still wholly or partly alive or even in full blossom in agreement with the tenacity of the correspond- ing ‘whales’ in Fig. I. This must be due to innovation within the scope of the methods leading to an extension of their capabilities and fields of application. Innovations Extensions of GFAAS Among the extensions of GFAAS (Fig. 5 ) several versions have ‘ES’ as part of their acronyms which reflects a trend from GFAAS to GFAES. The original GFAES as well as HA-FANES have more or less flopped while HC-FANES as a method for special purposes copes in particular with the problems of molecular background and adequate correction for this.* The most viable and interesting version appears to be FAPES (including GF-CCP) which uses a graphite furnace additionally heated by a radiofrequency dis- ~ h a r g e .~ - l ~ This development will enhance the possibility of extending graphite furnace techniques into the field of simultaneous multi-element analysis. It is interesting to see that the research on the GF-CCP started by Liang and Blades9J3 some 6 years ago has resulted in the development and commercialization of equipment for both emission and absorption.14 A report on the detection limits attained with this device shows striking improvements for a number of elements whose detection limits form a ‘weak‘ spot of ICP performan~e.~~ These improvements by one or two orders of magnitude with respect to the values reported by Winge et a1.,l6 concern in particular elements such as Ag As Cd Pb Sb Se Te T1 and Zn.In summary this work marks an innovation that supplements and extends (a) the GF technique with the possibility of multi-element analysis and (b) the ICP method by providing essentially improved detection limits for a particular set of elements without requiring operation in a vacuum although adaptations for use at various pressures can be made. Overall FAPES is a refreshing development not only in the sense of technological innova- tion but also politically as its acceptance in analysis might help to bridge the gap between the AES and AAS factions in the spectrochemistry community! Total-reflection X-ray Fluorescence Spectrometry A totally different aspect of ‘booms and trends’ is included in the ‘X-ray tree’ at the far right of Figs. 5 and 6 the birth and development of total-reflection X-ray fluorescence spectrometry for which the acronym TXRF has been generally adopted.X-ray fluorescence spectrometry (XRFS) was started in the mid 1950s as wavelength dispersive (WD) XRFS and later extended by energy dispersive (ED) XRFS. We optical spectroscopists know that XRFS is being used worldwide as a powerful tool in both research and industry. We also ‘know that XRFS leads a life of its own usually far away from our optical spectroscopic laboratories in particular research laboratories. The situation is certainly different in industries and government or private organizations where laboratory managers have to make the optimum choice of analysis methods to run their analyses efficiently and cost effectively. It would be useful however if also in optical spectroscopic research laboratories more attention would be paid to what happens in the X-ray field.Perhaps many optical spectroscopists are prejudiced about XRFS they think that the method deals with metals or geological samples requires large samples cannot handle solutions is precise but inaccurate has poor detection limits and is extravagantly expensive. That picture may have applied around 1960 but is no longer valid. An extremely important innovation is TXRF. Recent reviews may serve as key referencesI7-l9 and introductions to the principles of this method. Essentially in TXRF the sample is applied for example as a thin layer of a dried solution or slurry on a carrier of quartz glass or glassy carbon.X-ray radiation from a W or Mo tube is directed to a reflecting mirror or monochromator for selective filtration and subsequently to the sample at a glancing angle of about 4 min. As a result of this grazing incidence the beam is totally reflected at the carrier surface. The thin sample layer on the carrier is passed through by the primary and the totally-reflected beam whereby it is excited to X-ray fluorescence. The emitted radiation is detected by an Si(Li) detector mounted directly above the sample and is recorded as an energy dispersive spectrum. The essential benefits and limitations of this approach are summarized in Table 6 while conspicuous features are shown in Table 7. Note here that matrix separation is required not to avoid matrix effects but to achieve good detection limits. The amount of scattered radiation and hence the background increases proportionally to the matrix concentration.Also note the hidden or perhaps denied (Fig. 4!) question about the possible problems inherent in the drying step. Optical spectroscopists may consider all this as interest- ing but still take it for granted! However why is bringing up TRXF important in the context of plasma spectrochemis- try? Table 8 provides an answer. The crucial point is that TXRF brings XRFS into the hands of the wet chemist who in spite of all instrumental developments in the past 40 years has remained a key figure in the analytical chemistry picture. The question at the bottom of Table 8 has thus not been added without reason (cJ Tables 3 and 4).AnotherJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 77 1 I 1 \ I ~ ~~ Table 6 Essential benefits and limitations of TXRF Substantial reduction of the background intensity and duplication of the line intensity leads to improved SNR and detection limits (three orders of magnitude compared with classical EDXRFS) Use of thin specimens provides for simple and reliable quantifica- tion No matrix effects Fixed element-specific sensitivities Single internal standard for universal calibration curve requirement of separations Fig. 4) However a matrix worsens the detection limits entailing the Hidden or denied question is the drying step free of problems? (cJ ~ ~ Table 7 Conspicuous features of TXRF Microanalysis < 1 pg solid < 10 pl solution Trace analysis picogram level detection limits Direct Aqueous solution 1 pg ml-’ Acids 10 pg ml-1 Biological materials 10 ng ml-1 Ultra-pure metals 10 ng g-’ After matrix separation Multi-element capability 80 elements above Z = 11 (Na) Fields of application environmental mineralogical medical biological ultrapure reagents surfaces thin layers,.. . . . . . . . . . . Table 8 General reasons for bringing TXRF into the context of plasma spectrochemistry TXRF versus optical methods including MS TXRF is competitive or even more capable TXRF can handle solutions slurries powders tissues thin TXRF uses similar sample preparation methods TXRF fits the minds and hands of wet chemists TXRF is not fabulously expensive! Will history repeat itselj? layers.. . . . . Actual finally expectation upon release Initial A I Champions‘ view @ view Adversaries’ @ r7 8 Fig. 7 Fate of an analysis method faced in phases and faces with changed caps alluding to the competitive position of TXRF and illustrating that it is not the cap but the face that makes up the substance in the proposed iconographic rating of analysis methods IT= I ____________________.------ I I I I - 1950 1960 1970 1980 1990 GF-CCP question raised above in the section Assessing the Merits and Capabilities of Analytical Methods might be repeated here in a somewhat modified form Why are solutions often being sought to problems that others claim to have (better?) solved by other methods? Obviously the reasons are not different from those brought up above. Possibly TXRF may become a lever for bridging the gap between X-ray and optical spectroscopy and more impor- tantly between the two factions X-ray and optical spectros- copists.As an attempt to make the factions approach each other I mention the publication of the proceedings of a biennial workshop on TXRF in Spectrochirnica Acta Part B.20-22 To conclude I believe that the efficiency of research as well as instrument and methods development in atomic spectroscopy could substantially benefit if both groups would have a better understanding of each other’s fields. Whether familiarization with the principles and applica- tions of TXRF will induce plasma spectroscopists to change caps or not it is not the cap but the face that makes up the substance as illustrated in Fig. 7.Plasma Source AES and Plasma Source MS Fig. 8 brings us back to plasma spectrochemistry with the projection of a part of the ‘booms and trends’ picture (Fig. Fig. 8 Projection of a part of the ‘booms and trends’ picture of Fig. 1 on the block diagram of Fig. 6 with plasma source AES and plasma source MS highlighted 1) on a simplified version of the block diagram of Fig. 5 in which a blank oval puts plasma source AES and plasma source MS into the limelight. The oval might tempt the adversaries of these techniques to raise the ‘hopeful’ question symbolized in Fig. 9 but that is not what the iconographic rating program provides. On the contrary the program automatically tilts the oval and shows a family portrait with two friendly happy snowmen shaking hands (Fig.10). Their faces are not entirely identical but I had to accept what the computer dictated and the computer did so because I had furnished the input impressions derived from some recent conferences verbally summarized in Table 9. The last point stated in this table is emphasized and expanded in the block diagram ‘under construction’ depicted in Fig. 11 with in the right-hand upper corner a rising sun called ‘arc’. One reason for this is the present trend to explore and exploit solid sampling using such methods as direct sample insertion slurries and laser ablation. These approaches provide us of course with some of the possibilities of the arc avoiding however its instability but also introducing again many problems connected with solid sampling such as incomplete evapora-772 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL.8 1950 imo 1970 1980 iwo Fig. 9 Part 1 of a strip story Fig. 8 with a ‘face fit’ symbolizing a possible ‘adversaries’ view’ I BOOMS s. TRENDS^ GFMS - GFAES Fig. 10 Part 2 of the strip story Fig. 8 with a ‘face fi approximately symbolizing current reality tion selective distillation and thermochemical reactions. On the other hand selective distillation and thermochemi- cal reactions may be exploited to obtain emission or mass spectra of relatively volatile traces stripped of a possibly cumbersome spectrum of a refractive matrix in much the same way as the old ‘carrier distillation’ method23 or its numerous variants (cf ref. 24). That rising sun however has more to tell as preluded by the computer output faced in Fig.12 showing one of our two snowmen in a medallion happy and chuckling rubbing his hands! The message of the rising sun in Fig.13 is labelled ‘photographic plate’ but not really that plate itself but the arc methodology connected with it multi-line multi-element analysis and general survey analysis. Actu- ally the reason for the existence of this sun lies in another sun called ‘array’ (Fig. 14) which term refers to some major recent advances in the development of echelle spectrometers with several types of array detectors. Plasma Source AES Array Spectrometers This development reminded me of a perhaps long-forgotten article by Margoshes ‘Data acquisition and computation in Table 9 Brief assessment of the impact of plasma source MS on plasma source AES and the current positions of these two methods Initially strong ‘drain’from AES to MS- MS promised very low detection limits MS promised ‘no’ matrix effects MS promised much higher selectivity Both stabilizing in mutual interaction AES and MS mutually supplementary-combined systems? Severest handicap of MS matrix effects; ‘no’ has evaporated into Plasma source chiefly argon ICP MIP-AES for special purposes (e.g.in GC or LC) He-MIP-MS as supplement (Fe As Se Br) Chiefly quadrupole mass spectrometers Double focusing high-resolution mass spectrometers entering Ion trap and time-of-flight MS cradled MS appears ‘stagnant’ in details of applications AES and MS are both ‘fighting’ with solids At present- the spectrometer! practice spectrochemical analysis’,25 from which I might cite two statements ‘.. . . . .A spectrometer employing a television camera tube could have many advantages.. .However many problems must be solved before such an instrument could be made practical.. .’ It appears that this 1970 Midsummer- Night’s Dream has finally become a reality! Denton and co-workers in particular must be credited with having performed extensive ~ t u d i e s ~ ~ - ~ ~ aimed at the implementation of two-dimensional (2-D) array detectors in ICP-AES. Various efforts have resulted in the develop- ment of commercial instruments using different types of echelle spectrometers with 2-D dispersion and different types of 2-D array detectors briefly characterized by the data given in Table 1 033,34 and Table 1 1 ,35,36 respectively.The future will have to show how these systems perform in practice and how the constraints inherent in array detectors have been compromised to meet the requirements of wide spectral range small spectral bandwidth high detector resolution (=number of pixels per unit of bandwidth) signal-to-noise ratio ruggedness and cost effectiveness. Improved Insights and Chemometrics Fig. 14 contains an overlaid block with the headings ‘Improved insights into the spectroscopic methodology’ and ‘Chemometrics’ suggested as an input item for ‘Plasma source AES’ on the same level as input item ‘Echelle spectrometer-array detector’. The suggestion implies that the advent of echelle spectrometers with array detectors opens perspectives for advanced applications of recently gained or improved insights into the spectroscopic metho- dology in general as well as applications of results of new developments in chemometrics.In the following sections I shall recapitulate a few issues as a basis for pointing out some directions from which further developments can be expected. Application of Improved Insights in Plasma Source AES Array Spectrometers and SBR-RSDB Approach It is no secret that in recent years I have crusaded to convince the world that the use of signal-to-background ratio (SBR) in combination with the relative standard deviation of the background (RSDB) has a number of advantages over the approach using signal noise and signal-773 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 ICP MIP Fig.11 Phase 1 of the construction of a block diagram emphasiz- ing the exploration of techniques for solid sampling in plasma source AES and MS. The rising sun symbolizes these developments as a reincarnation of the ‘good old arc’. Acronyms are exdained in Table 1 in spectrochemistry 1950 1960 1970 1980 1990 W ) W Fig. 12 Part 3 of the strip story Fig. 8 with a ‘face fit’ symbolizing and emphasizing another current reality and its perspectives to-noise ratio (SNR). To convince a person or a group of people of the appropriateness of a thesis a proposal or an idea it does not suffice to show ‘that something works’ or even ‘that it works better than something else’ one should also show why it works better and what is gained. This requires one to penetrate profoundly not only into the approach one wishes to recommend but also into the approach one wishes to banish.In the case of the SBR-RSDB and SNR approaches there was fortunately nothing to banish but a lot to compare and above all to connect. I have tried to do that in a series of lectures the preparation of which as well as the discussions following them have gradually enhanced my own insight into this delicate matter with the result that I could eventually let this insight culminate in a paper ‘Atomic emission detec- tion limits more than incidental analytical figures of merit!-a tutorial discussion of the differences and links between two complementary appro ache^'.^' This paper along with three papers dealing with the theory and measurement of detection limits in ICP-AES using the SBR-RSDB a p p r ~ a c h ~ * - ~ ~ and the preceding outpost skir- mishes in the lectures have probably prompted the defini- tive infection of the North American spectroscopy commu- nity with the SBR-RSDB virus.This happened some 45 years after Kaiser published the fundamental work ‘Die Berechnung der Nachwei~empfindlichkeit’,~~~~~ the nursery from which the virus spread over Europe. At present the SBR-RSDB virus appears to have settled well in North America even to the extent that Hieftje’s group has launched within the incubation period a program for data collection and calculation of figures of merit using the SBR-RSDB as an electronic publication in Spectrochimica Acta Ele~tronica,~~ while the approach has been recently applied in the scope of the development assessment and performance testing of a new type of Cchelle array s p e c t r ~ m e t e r .~ ~ - ~ ~ It may be interesting to look in that context again at the SBR-RSDB approach and to show in which respect this approach also provides a convenient framework for understanding why and how array detectors may bring us an eagerly sought after crucial improvement of the precision in ICP-AES and a concomitant improve- ment in the detection limits. As an aid for appreciating the arguments the following tutorial introduction may be useful. Basically the SBR-RSDB approach involves three vital equations from which other equations may be developed for specific situation^.^^-^^ First we have the equation for the detection limit (cL) (1) CO c,= k x 0.0 1 x RSDB= - SBR where c is the analyte concentration to which the SBR applies and k is a statistical factor chosen to be 2 2 2 or 3.Note that in this equation RSDB is expressed in %. The same will apply to the related quantities RSDN aA and aB introduced in the equations that follow. The second equation specifies RSDB:37-39 Y RSDB= in terms of coefficients for source flicker noise (aB) shot noise (D) and detector noise ( y ) and the background signal (X,). Eqn. (2) has been further developed into a form convenient for dealing with the detector noise,39 but it would only unnecessarily complicate the present discussion to consider that equation here. Let it suffice to say that detector noise may play a predominant role in commercial instruments using photomultiplier tubes (PMT) in particu- lar in the low UV spectral region,4o and also in instruments with array detectors unless they satisfy particular require- ments as indicated below.In the present tutorial we may confine discussion to situations with a negligible detector noise contribution (7x0 and/or XB is large) r--- The third equation formulates the relative standard deviation (RSDN) of the net line signal (X,) as a function of SBR X and the various noise coefficient^:^^-^^ whereby an additional coefficient a covers the flicker774 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 Arc methodology Photographic plate 0 Multiline multi- element analysis 7-1 0 General survey I analysis j U Plasma source AES ICP 0 MIP Fig. 13 Phase 2 of the construction of the block diagram (started in Fig.1 1 ) emphasizing the predictable rebirth of the essential arc methodology prompted by the reshaping of the ‘photographic plate’ in the form of array detectors (Fig. 14) 0 General survey 0 Spectrum resolution ICP 0 W I ? Spectrum simulation True detection limit 0 tine selection and Al Chemometrics Multivariate analysis 0 Multicomponent L analysis Kalman filters Fig. 14 Phase 3 of the construction of the block diagram (Figs. I 1 and 13) emphasizing not only the foreseeable renaissance of the essential arc methodology induced by the recent maturing of echelle spectrometers with array detectors but also expansions of this methodology as a result of the exploitation implementation and further exploration of recently gained insights into the spectroscopic methodology and advancements in the field of chemometrics noise in the net line signal.Coefficient aA may be of the same magnitude as a but this is not necessarily so. If we assume that a A = a B then eqn. (3) may be conveniently written as I This result is obtained by combining eqns. (I) (2) and (3). Finally if y=O and SBR is large then eqn. (3) may be converted into I Table 10 Brief characterization of Thermo Jarrell Ash IRIS-CID ichelle spe~trometer~~,~~ Conventional echelle arrangement with toroidal camera mirror CIDI 7BAS array (CIDTEC Liverpool NY USA) pixel 23 pm x 27 pm 388 pixels x 244 pixels 8.7 mm x 6.6 mm !Special phosphor to increase quantum efficiency in UV Cryogenic cooling to 135 K !Spectral bandwidth 20 pm !Spectral range 170-800 nm which is the net line equivalent of eqn.(2a) for the background. The similarity of the two equations is immedi- ately understood if one considers that a large SBR in fact means that the background is negligible. With the present state of the art we must be generally satisfied with values of the flicker noise coefficients of about 1% or slightly lower. Therefore the minimum value of RSDB will also be about 1 O/o and this condition is met if the background signal X (as the resultant of the background radiant flux and the detector sensitivity) is high enough to make the shot noise and detector noise terms in eqn. (2) negligible. As noted above with PMTs and most array detectors this cannot be achieved in the low UV. However whenever it can be realized we have a situation in which the flicker noise term dictates the lower limit of RSDB.A property of array detectors is that virtually simulta- neous measurements can be made at adjacent wavelengths in the spectrum. Since it is likely that the intensity signals measured at such wavelengths are correlated one may exploit the correlations involved by instantaneous ratioing of the intensities. It is irrelevant here how this is precisely implemented in the hardware and software. It is essential that one can define a ‘measure’ in terms of a ratio either a classical quotient of just two signals or in a multivariate form and that the flicker noise of this ratio will approach zero if the correlations are intrinsically perfect and are fully exploited. Consequently if we also represent in this case the flicker noise coefficient by aB then the RSDB will be limited by shot noise and detector noise rather than flicker noise.Such a situation is represented in Fig. 15 not as an innovation but as a revitalization of an ‘old truth’ reproduced from a paper dealing with PMTs published in 198 1 .46 Actually the figure published was not for RSDB but for RSDN. However it referred to conditions where eqns. (2a) and (3b) are valid whence it may be taken to represent both RSDB as a function of X and RSDN as a function of X,. What is crucial is that the diagram shows the experi- mental curve of the RSDB or RSDN to reach a constant level of 1% when the intensity exceeds a particular value. This constant level is the flicker noise limit. In the original publication the curve for the shot noise component was included to show that the RSDB or RSDN is entirely dictated by shot noise at the lower end of the intensity range.In contrast in the present context it is the upper end of the intensity range which deserves our attention since array detectors can permit a switch to the curve for the shot noise component as the ‘experimental’ curve. This has been recently demonstrated by Barnard et af.36 and Ivaldi and B a ~ n a r d ~ ~ to be a reality for the array spectrometer they explored. This point is documented here by merely reproducing a figure from the latter paper as Fig. 16 whereby the reader is referred to that paper for explanations. A vital requirement for obtaining results of the type shown in Fig. 16 is that a sufficiently large background signal be obtained.Otherwise the working point will lie at the lower end of the range where shot noise is predominant making any attempt to exploit the correlations in the flickerJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 775 ~~ Table 11 Perkin-Elmer segmented CCD array (SCD) echelle spectrometeP~~~ Non-conventional echelle spectrometer- Separate output regions for UV and VIS Each optimized for resolution and throughput Range 167-782 nm Bandwidth 6 pm at 220 nm High throughput luminosity per unit A = 72 x luminosity of Thermo Jarrell Ash IRIS system Segmented CCD array detector (SCD)- Custom integrated circuit 224 linear array segments totalling Covering 5.7% of the spectrum (1 67-782 nm) Potentially 5000 lines 3-4 primary lines of each of 72 elements Pixel width 12.5 pm Pixel height 80-1 70 pm Detector cooled to -40 “C Virtual gate buried-channel structures Front side illumination No overlaying poly-silicon gate structure-maximum UV quantum efficiency David Sarnoff Research Center Pinceton NJ 16 photolithography mask layers 300 semiconductor processing steps 6336 pixels 0.1 I 1 x lo2 1 x 10’ 1 x lo‘ 1 x 10’ 1 x lo‘ I 1 I J Background or net line signal (abitrary units) Fig.15 Relative standard deviation of background (RSDB) or net line signal (RSDN) in dependence on the corresponding back- ground (A’,) or net line signal (X,) respectively. The diagram shows the experimental curve for an EM1 9789 QA PMT reflecting the contributions from source flicker noise and shot noise and the curve for the shot noise component alone as derived from the experimental curve by a theoretical analysis.Reproduced with permission from Boumans P.W.J.M. McKenna R. J. and Bosveld M. Spectrochim. Acta Part B 198 1 36 103 1 noise ineffective. A high optical throughput of the spectro- meter and a high quantum efficiency of the detector in turn are the prerequisites for obtaining a high background signal since the ‘intensity resources’ at the side of the ICP are virtually exhausted. This has been achieved in the pertinent spectrometer (cJ Table 11). What consequences has the reduction of the flicker noise on analytical figures of merit? First if we are able to reduce RSDB from 1% to for example O.l% this implies according to eqn.(1) an improvement of the detection limits by a factor of 10. On the other hand the precision of the net line signal at the detection limit will fundamentally not improve since this precision is entirely dictated by the second term under the square root sign in eqn. (3a). This I 0.1 1 9 -<. 0 %s 10 100 1000 10000 Background sig na I/cou n ts s-’ Fig. 16 Theoretical and experimental plots of RSDB versus background signal as obtained with a segmented CCD array (‘SCD’) Cchelle spectrometer (Table 1 1). All curves are theoretically derived approximations representing total noise shot noise and flicker noise respectively whereas the points are experimental data. In contrast to Fig. 15 the present figure includes experimental points for the shot noise component alone as obtained through ‘multicomponent spectral fitting’.The diagram demonstrates that the array spectrometer permits the elimination of the source flicker noise component from the experimental results. Reproduced with permission from Ivaldi J. C. and Barnard T. W. Spectrochim. Acta Part B 1993 (ref. 45). precision in terms of RSDN would thus remain 50% if k = 2 G and about 50% if k=3. However this precision is reached at a 10 times lower detection limit while the limit of determination (RSDN= 10%) now coincides with the ‘former’ detection limit. If correlations in net line signals can be exploited in a similar way an essential gain in the overall precision of the method comes within sight. This is illustrated with the aid of a classical picture which I must have shown for the first time in 197847 and has since appeared in various publica- tions or tutorials e.g.refs. 39 and 48. It is reproduced here in a slightly modified form as Fig. 17. The diagram is essentially a representation of eqn. (3a). The curves are for various values of a namely 5 2 1 and 0.5% respectively. For obvious reasons the curves have a shape similar to that of the experimental curve in Fig. 15. Also for obvious reasons each curve reaches a plateau at a relatively high analyte concentration corresponding to a value of for example c/c,= 500 which in turn corresponds to SBRs of 70 28 14 and 7 for the respective curves from top to bottom; in the plateaus RSDNSCY,. Fig. 17 can be extended with curves for still smaller values of CY repre- senting situations that may be realized with array detectors if the correlations (or anticorrelations?) in the flicker noise of the line signals at different wavelengths are well exploited.The set of curves might eventually include the shot noise limit shown as the broken line in Fig. 17. If this could be actually achieved in ICP-AES the precision of ICP-AES would become competitive with the precision of XRFS which is high (RSDNzO. 1%) because XRFS does not cope with the critical feature of optical methods flicker noise arising from fluctuations in sample introduction and its repercussions on the source conditions. Line Selection in ICP-AES The overlaid block in Fig. 14 includes ‘line selection and AI’ (artificial intelligence) as a separate item. However ‘line selection’ does not stand on its own but is firmly linked with all the other topics listed in the block.Two questions are of vital interest here. Firstly what progress has been776 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 50 10 A - $ 5 z P v) a 1 0.5 - Limit of \ a A 5 2 1 I 0.5 determination \ \ 1 1 1 \ I 1 50 100 5001000 0.1 1 5 10 C/CL Fig. 17 Plots of the relative standard deviation of the net line signal (RSDN) as a function of the ratio of the concentration present to the detection limit (c/cL) according to eqn. (3a) for various values of the source flicker noise coefficient (a,) 5 2 1 0.5% and 0 respectively. Adapted and reproduced with permission from Boumans P. W. J. M. Fresenius’ Z. Anal. Chem. 1979,299 337 made in recent years? Secondly what will be the impact of array spectrometers and comparable multichannel instru- ments? The former question is considered in this section the latter in the next.The introduction and the gradual understanding and penetration of the concept of ‘true detection limit’ has induced researchers to devise and implement chemometric procedures not only to facilitate line selection but also to correct for spectral interferences due to line overlap. The concept introduced and elaborated in the second half of the 1 980s,49-54 sprouted from our studies on high-resolution spectrometry and our initial disappointment about the fact that high resolution brought only rather marginal profits for the detection limits if the contribution from an interfering line to a gross analyte line signal was treated in the same way as continuous backgro~nd.~~ Accepting this hard ‘truth’ was difficult.The problem was not a failure of high- resolution spectroscopy which could not be reproached for not behaving as it should physically. The case in point was that the contribution from an interfering line should be brought into the context of ‘selectivity’ and not be consi- dered as if it were merely a simple addition to the background under the analysis 1ine.52~53 What this means is elucidated in Fig. 18 which shows a line that is thought partly to overlap an analysis line (not shown) thus contributing an interfering signal XI at the peak wavelength Aa of the analysis line. The picture further shows the contributions from the original background (XB) and back- ground due to a continuum or line wings (X,) produced by the interferent. The basic idea was that continuous back- ground (even if slightly sloping) can be accurately deter- mined by one- or two-point measurements.However this is impossible with the interfering line signal since an accurate measurement would make demands on the accuracy of the wavelength positioning device of the spectrometer that are incompatible with the actual state of the art. This problem manifests itself not only with the measurement of XI in the situation shown in Fig. 18 i.e. for the spectrum of the pure interferent but even more seriously in the sample spec- trum where we can only observe the resultant profile of analysis line and interfering line (Fig. 19). In conclusion an interfering line signal had to be considered as a contribution t o the background that can be measured only with a far larger uncertainty than continuous background if tradi- tional peak height measurements are applied.It was this insight that prompted the introduction of the concept of k Wavelength - Fig. 18 Schematic representation of the situation that results if an interfering line partly overlaps an analysis line having its peak at wavelength la. The interfering signal is made up from three distinct contributions X,=interfering line signal; Xw=interfering continuum signal; X,= original background (pure water) I I 1 Wavelength - Fig. 19 Line profiles observed for a blank solution of an interferent and the same solution spiked with analyte. The peak of the analysis line is located at wavelength la.To determine the net line signal (X,) accurately it is required to make an accurate measurement of the gross signal (X,+ X,+X,) the interfering line signal (XI) and the background signal (XB). The peak height measuring mode precludes accurate measurement of the former two owing to wavelength positioning errors in a spectrometer. This contrasts with the scanning mode in combination with a multivari- ate technique. Reproduced with permission from Boumans P. W. J. M. and Vrakking J. J. A. M. Spectrochim. Acta Part B 1987 42 819 ‘true detection limit’ (cL to be distinguished from the ‘conventional detection limit’ (cL ,,,,) and the ‘common detection limit’ (cL) for pure water as follows. The detection limit for pure water (or diluted acid) is defined by eqn.(I) which may also be written in terms of the background equivalent concentration cBEQ instead of the quotient cdSBR (4) C = k x 0.0 1 x RSDB x cBECJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 C may be ') (iterative calculation) (iterative operation) (' must be '1 (' may be '1 777 With reference to Fig. 18 the conventional detection limit is then defined analogously where cWEQ and cIEq are the equivalent concentrations associated with the signals Xw and XI the sting being in obtaining a realistic value of RSDB in order to let c ~ ~ ~ ~ ~ reflect a realistic situation! Various considerations have prompted the introduction of the true detection limit according to this definition V CL true= - 5 CIEC + CL conv (6) where v is a parameter whose value is likely to lie between 0 and 2.In eqns. (5) and (6) we may now use a value for RSDB of the order of 1% such as it would be derived from a series of intensity integrations at La with a fixed wave- length setting of the spectrometer while a solution of the pure interferent is nebulized. This is so because we have made a distinction between two detection limits an unrealistic one cL conv and a realistic one cL The latter not only provides a fair estimate of the detection limit that can actually be achieved under real analysis conditions but is also by excellence the criterion for line selection in trace analysis of real The implementation of the cL true concept in ICP-AES has been illustrated in various p ~ b l i c a t i o n s ~ ~ ~ ~ ~ ~ ~ ~ while an electronic publication on spectrum simulation has made the tools available for the 'readers' to perform case studies on their own computers.57 However all that work emphasized the diagnostic aspects of the problem but did not directly contribute to remedying the disease i.e.providing means for nullifying or at least reducing the disastrous effect of line interference on the true detection limit. It is the merit of van Veen and c o - w o r k e r ~ ~ ~ - ~ ~ that they were the first to meet the challenge and to take up the gauntlet. Their work involves the application of a multicomponent or multivari- ate technique known as 'Kalman filtering'. This approach has brought the desired 'release' as is well explained in the pubications of van Veen and co-workers.The essence is the judicious collection of such additional spectral information of analytes and interferents that the magnitude of interfer- ing line signals (XI) can be accurately 'predicted' which in terms of eqn. (6) means that the value of parameter v is reduced to zero. This additional information is obtained from scans instead of simple peak height measurements. If the value of v is reduced to zero the true detection limit becomes equal to the conventional detection limit. The risk of line interference is thus diminished to that produced by a simple background enhancement equalling X I . A further consequence is that the conventional detection limit may now be used as the criterion for line selection which avoids some complications and is more straightforward.The approach also entails an appreciable relief of the require- ments upon the dynamic range of databases for the initial tentative line selection preceding the definitive measure- ments involving Kalman filtering.62 Yang and c o - ~ o r k e r s ~ ~ - ~ ~ have made an in-depth analysis of the factors implied in parameter v in eqn. (6) and also established under which conditions Kalman filtering tends to bring the sketched profits and when not. Ivaldi et al.67 have tested an alternative multivariate method for increas- ing the quality of the information extracted from ICP spectra also involving spectral scans instead of peak height measurements. Their publication provides keys to addi- tional literature. I off-line (available data base) on-line (ad hoc data collection) 1 a prior/ ( single element determinations (' may be ' I 2 multielement analysis off -I ine on-line multielement analysis a posterlor/ I multiline analysis I I Fig.20 Schematic representation of possible protocols for line selection in AES trace analysis as explained in the text Pure substance simple spectrum Pure substance complex spectrum ' Known ' simple mlxture I \ Istmpie/complex spectrum I I I Requirements I 0 Criterion 0 Data base 0 Knowledge of sample composition slmplelcomplex spectrum U Fig. 21 Schematic representation of situations permitting in principle a priorz line selection in AES trace analysis. The conditions grow steadily more difficult in the direction of the arrow making increasingly more severe demands upon data base knowledge of the sample composition and spectrometer flexibility although strictly speaking a posteriori line selection becomes mandatory only if all knowledge on the sample composition is lacking (Fig.22) Line Selection and Multichannel Spectrometers Generally we may classify approaches to line selection in AES trace analysis on the basis of the schedule presented in Fig. 20. Accordingly the first possibility is a priori line selection which may be done either off-line or on-line. In the former case we must have a database available in the latter we collect dedicated data ad hoc. This approach may be applied to single-element determinations or to multi- element analysis. More powerful is a posteriori line selec- tion. The off-line mode implies iterative calculations using the data measured in a complete spectrum such as happened in general survey analysis using a d.c.arc and photographic detection with an advanced automated den- sitometer.'j* The on-line mode implies not only iterative calculations but also iterative operation to collect data. It is feasible only with multichannel detection. Application of either off-line or on-line a posteriori line selection requires the analysis to be a multi-element analysis since the results for the one element are needed for decision making with respect to the other. It may be a multi-line or multiple line analysis i.e. a multi-element analysis using more than one analysis line per analyte. This is the ideal approach but its implementation requires the availability of hardware and software that provide rapid access to several hundred spectral lines.This was actually so with the now defunct d.c.778 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 ~~ Table 12 Plasma Spectrochemistry Conferences Prehistorical Time the Stone Age- ICP Information Newsletter founded ICP Round Table Discussion XVIlI CSI First European ICP Symposium Amherst MA USA Grenoble France Munich Germany Transient Era the Golden Age- Noordwijk aan Zee The Netherlands First ICP Conference Noordwijk aan Zee The Netherlands Second ICP Conference San Juan Puerto Rico International Winter Conference on Atomic Spectrochemical Analysis with ICPs MIPS and DCPs Historical Time the Silicon Age- Orlando FL USA San Diego CA USA Leysin Switzerland Kailua-Kona HI USA Lyon France San Diego CA USA Reutte Austria St.Petersburg FL USA Dortmund Germany San Diego CA USA Granada Spain San Diego CA USA June 1976 September 1975 June 1976 June 1976 April 1978 January 1980 1982 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 Barnes editor Robin chairman Kontron sponsor de Galan de Galan Barnes Barnes Barnes Mermet Barnes Mermet Barnes Wegscheider Barnes Broekaert Barnes Sanz-Medel Barnes Es=l\1. 0 Data base Unknown ',comple mlxture vrrl8ble 0 Hardware I Software 0 The ' old ' knowledge and experience of Fig. 22 Schematic representation of the situation that makes a posteriori line selection indispensable. Actually this is the situation to be covered by general survey analysis formerly entrusted to the d.c.arc in combination with photographic recording of the spectra. The advent of array spectrometers opens perspectives for a renaissance of the old arc methodology involving multi-line multi- element analysis arc system for general survey analysis used for many years in Philips Research Laboratories6* Which condition essentially dictates whether a priori or a posteriori line selection can or has to be used? Fig. 2 1 covers a series of situations that in principle permit a priori line selection. However all situations have as a common denominator the condition that the sample composition should be a priori 'known' the only difference between the situations being that the complexity of the sample increases from top to bottom making thus ever higher demands upon both the database and the flexibility of the spectrometer.The criterion is always the same namely the true detection limit or the conventional detection limit depending on whether a multivariate approach such as Kalman filtering is used or not. NOordwljk 197U - 1978 Purrlo Rko 1980 0 Orlando 1002 ff h n Ol.00 1984 ff Lapin 1985 Hiwall 1986 Lym W? &n Mwo lOl8 * Routla 1969 St htrraburp 1)90 Oomnund loo1 * &n Dbgo 1992 Graruda 1903 'LASMA SPElXROCHEMISTRY CONFERENCES # ,rd B I 6 P e c 4 i 7 Fig. 23 Erecting a triumphal arch for the 'good old arc' might still seem premature. Erecting it in honour of the Plasma Spectroche- mistry Conferences their Venues and Organizers (see attic at other side) is entirely appropriate along with a special tribute to Ramon M.Barnes and his ICP Information Newsletter which lent a charm to our 'Life with for and through the ICP' and made it more comfortable In contrast as Fig. 22 shows an 'unknown' complex mixture with variable composition precludes a priori line selection making a posteriori line selection mandatory. In fact a system using a posteriori line selection should be analysis proceed concomitantly and the consistency 01 the concentration values found with different lines of each analyte is used as the main criterion. This was the way in which the d.c. arc system referred to above was operated. It appears that the advent of powerful spectrometers with array detectors and perhaps also other types of multichan- nel instruments will produce a revitalization of 'spectrogra- phic general survey analysis' in the sense of casting the old arc methodology into the mould of modern technologies,JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL.8 779 fully profiting from the abundant possibilities of modern hardware and software. The greatest challenge will then be to achieve a balanced integration of old practical experi- ence knowledge available in the arsenal labelled ‘spectros- copic methodology’ and ‘abstract’ chemometrics. One might thus predict that the year 2000 will have seen the comeback of the arc in the jacket of an arch of the type shown in Fig. 23. Plasma Spectrochemistry Conferences To prevent premature celebrations the arch in Fig. 23 has been cautiously erected not for the arc but in honour of both the ICP and the Plasma Spectrochemistry Confer- ences whose venues are carved in the attic of the arch like battlefields in ancient times.The side of the arch shows the Imperator’s name Barnes along with his attribute the ICP Information Newsletter the sponsor and promoter of many conferences. The names of the Chairmen of the Confer- ences carved at the back of the arch are listed in Table 12 under three sub-headings characterizing the eras. Although it is not a Spectrochemistry Conference I found it appropriate to open the listing by making reference to the foundation of the ICP Information New~letter,~~ shortly before a Round Table Discussion in Grenoble acted as the germ of the Plasma Conferences. This discussion immediately following a cocktail party has been one of the best open discussions in the history of the ICP.The report in the Newsletter is still topical.70 The Stone Age was followed by the turbulent Golden Age also marked by open discussions unspoilt by commerce and trade fully recorded transcribed and afterwards published in edited form in the New~letter.~~~ In that period in particular the Newsletter disseminated a wealth of information including ‘Questions’ from readers and ‘Answers’ from pioneers two of which are listed in Table 1 3 for both instruction and entertainment! The last stage the Silicon Age was less turbulent than the previous era yet most interesting and challenging. Table 12 lists a continuous stream of streamlined Winter Confer- ences with sun or snow and skis or snorkels. These conferences have contributed greatly to communication among spectroscopists primarily Europeans and North Americans.The latest conference in Granada might prelude an extension of the communication lines in such a way as to embrace also Latin America in this network. Intensifying our contracts with Latin America is important not only to disseminate spectroscopic knowledge and promote the proliferation of modern spectroscopic methods and ideas in that part of the world but also to bring together people whose cultures have been continuously connected in the past five centuries. It will be a challenge to discover these connections personally on the track of what the Mexican Table 13 Samples from ‘Questions’ including the ‘Kinnunen Questions’ (1 975)71*72 Class of spectral lines best used with ICP arc or spark? Any special Answer- criteria for selecting lines? Arc lines No special criteria except perhaps interference by matrix lines How much wet chemistry has been replaced by ICP? Answer- Too early to tell how much has been replaced Predictable that the ICP will replace wet chemical analysis (including AAS) where a multi-element technique is more economical than single-element methods writer Carlos Fuentes has pictured in his fascinating book ‘The Buried Mirror’.73 Let that mirror be dug up in search of innovation or confirmation! Conclusions If a spontaneous discussion on the ICP at the XVIIIth CSI in Grenoble in 1975 is marked as the start of the ‘Plasma Spectrochemistry Conferences’ this institution will cele- brate this year its 18th birthday the age at which in many parts of the world youths reach maturity.Plasma spectro- chemistry itself is much older being cradled in the early 1960s. In spite of many explosive developments it is rejoicing and encouraging to see that the field still shows a remarkable vitality which prompts innovations such as furnace atomization plasma emission spectrometry and practically usable Cchelle array spectrometers. The latter development opens the door for an effective implementa- tion of many insights into the spectroscopic methodology that have been obtained in the past decade. This in turn may entail the reincarnation of the multi-line multi- element methodology associated with the now defunct arc. Also the present state of the art of array detectors solicits the exploitation of correlations in the spectra.A judicious application of these correlations could provide a lever for nullifying the adverse effects of source flicker noise on the precision of optical spectroscopic methods. If in this way the effect of flicker noise could be banished then the precision of optical methods might become competitive with that of X-ray fluorescence spectrometry. On the other hand plasma spectrochemists should be well aware of developments in the X-ray field such as the maturing of total-reflection X-ray fluorescence spectrometry which is capable of handling samples as solutions and slurries although often requiring chemical separation or preconcen- tration. However it appears that also in plasma spectroche- mistry ever more chemistry is involved but chemistry with a better status than formerly having gained appreciably in social prestige and standing from its happy liaison with the plasmas and the spectra of plasma spectrochemistry.1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 References Plasma Spectrochemistry guest ed. Barnes R. M. Spectro- chim. Acta Part B 1983 38 pp. 1-445. Developments in Atomic Plasma Spectrochemical Analysis ed. Barnes R. M. Heyden London 1981. Boumans P. W. J. M. in Inductively Coupled Plasma Emission Spectroscopy Part 1 Methodology Instrumentation and Per- formance ed. Boumans P. W. J. M. Wiley New York 1987 p. 93. 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Rev. 1974 34 322. 69 ICP InJ Newsl. ed. Barnes R. M. 1975 1 1. 70 Scott R. H. ICP Inf Newsl. 1975 1 144. 71 ICP InJ Newsl. 1975 1 46. 72 ICP In$ Newsl. 1976 1 206. 73 Fuentes C. The Buried Mirror Reflections on Spain and the New World Houghton Mifflin 1992. Paper 3/01321I Received March 5 I993 Accepted April 3 1993

ISSN:0267-9477    

DOI:10.1039/JA9930800767

出版商:RSC    

年代:1993

数据来源: RSC

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JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 78 1 Inductively Coupled Plasma Mass Spectrometry of Biological Samples* Invited Lecture Carlo Vandecasteele Department of Chemical Engineering University of Leuven de Croylaan 46 B-300 1 Heverlee Belgium Hans Vanhoe and Richard Dams Laboratory of Analytical Chemistry Rijksuniversiteit Gent Proeftuinstraat 86 8-9000 Ghent Belgium The determination of trace and ultra-trace amounts of elements in biological samples by inductively coupled plasma mass spectrometry is discussed. Most attention is paid to human serum but other materials are also considered. Matrix effects and their correction using internal standards are discussed in detail together with the determination of Zn B Mo and Sn in serum. An overview is also given of the results obtained on a ‘second generation’ serum reference material.Keywords Inductively coupled plasma mass spectrometry; biological samples; human serum; matrix effects The determination of trace and ultra-trace amounts of elements in biological samples has been and still is the subject of numerous investigations. One of the most difficult biological samples from the point of view of trace element determinations is human serum which contains very low concentrations of several elements of potential interest. Atomic absorption spectrometry (AAS) atomic emission spectrometry (AES) proton-induced X-ray emis- sion (PIXE) and neutron activation analysis (NAA) have all been frequently used for the determination of trace elements in serum. Electrothermal AAS (ETAAS) and radiochemical NAA (RNAA) offered the greatest possi- bilities. Other techniques at the concentration levels that occur in serum are limited to a few trace and minor elements.Table 1 presents a survey of this situation.*.* The AAS technique has the disadvantage that only one element can be determined at a time; for NAA the main disadvantages are that a nuclear reactor is required and that the results are usually obtained only after a relatively long delay (up to several weeks). An alternative method was therefore needed and starting from about 1986 attempts were made to use inductively coupled plasma mass spectro- metry (ICP-MS) for this purpose. Table 1 Overview of techniques for trace and ultra-trace determi- nations of elements in human serumlJ Element V Cr Mn Fe co Ni c u Zn As Se Rb Mo Cd Sb cs Hg ETAAS X X X X X X X X X * X * X X X X * x t - * Hydride generation AAS.t Cold vapour AAS. RNAA X X X X X X X X X X - X X - - X * Presented at the 1993 European Winter Conference on Plasma Spectrochemistry Granada Spain January 10-1 5 1993. The ICP-MS method of measurement has several advan- tages for trace element determination (quasi-)simultaneous multi-element determinations are possible; excellent detec- tion limits; wide linear dynamic range; and high sample throughput. However it also has a number of disadvan- tages matrix effects; and for quadrupole MS the occurrence of interferences due to polyatomic ions and to doubly charged ions. For these reasons when studies on trace element determi- nations in human serum by ICP-MS were initiated it was not at all clear whether this technique would ever provide useful and accurate data for trace elements in serum.In this paper the possibilities of using quadrupole ICP-MS for the determination of trace elements in human serum are considered. Some attention is also given to the analysis of other biological samples. Matrix effects and methods to correct for them are discussed first. Polyatomic interfer- ences (and interferences from doubly charged ions) are related to the choice of the analytical indicator isotope and only a few examples therefore are discussed. Matrix effects Human serum contains large amounts of proteins (60-80 g 1-*) and dissolved salts (approximately 10 g l-l) which can lead to clogging of the pneumatic nebulizer of the central tube of the torch and of the entrance aperture of the sampling cone. To avoid these effects the sample can be digested with acid.This has the drawback of introducing significant blanks and can also cause losses of volatile elements unless use is made of closed systems. It was therefore decided3 to apply where possible a simple dilution only. This leads of course to poorer detection limits. In general the sample was diluted 5-fold with 0.14 mol 1-l HNO,. To illustrate the occurrence of matrix effects 10 pg 1-l of T1 were added to 0.14 mol 1-l HN03 (blank) and to five 5-fold diluted serum solutions. Fig. 1 shows the 205Tl signal as a function of the number of the consecutively measured solutions. It appears that the signal is suppressed in the sample compared with the blank by an average of about 16% and after measurement of five such serum solutions the original signal is obtained again.The question is which components in the serum cause the suppression (or in general a change) of the analyte signal. From the compo- sition of serum it is most likely that proteins and easily ionized elements such as Na Mg K and Ca contribute to the suppression. In order to simulate the influence of proteins glycocolJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 782 30 cn c C .- 2 E 20 e c .- I g 5 10 Y- e m C cn z 0 I I I I 1 I I 1 I 2 3 4 5 Blank Blank 1 Solution Fig. 1 Influence of serum matrix (5-fold diluted) on 205Tl+ signal (1 2 3 4 5=5-fold diluted serum solutions and blank= 0.14 mol I-' HN03) cL 0.6 Y- : 5 10 15 20 25 30 35 - 2 0.4 c n o iTj Carbon concentratiodg I-' Fig.2 glycocol solutions containing 100 pg I-' of In l151n signal as a function of the carbon concentration for .$ 0.8 C 3 ; 0.2 Y- t s I a l l I i T j 0 2 4 6 8 10 12 cn NaCl concentration/g I-' Fig. 3 Influence of NaCl concentration on the l151n signal ' O ' 60 .- '0 50 cn 40 2 30 iTj 20 Q 3 C cn 101 1 1 I I I 0 50 100 150 200 250 Mass number of nuclide Fig. 4 Percentage suppression by 4 g I-' NaCl as a function of the mass number 1 2 3 4 5 6 7 8 9 10 v ) ' NaCl concentration/g I-' Fig. 5 Suppression of 1151n signal by NaCl and recovery of the signal when a pure In solution is measured after a 2 min cleaning time I I I I I 6 8 10 0.20 I 0 2 4 NaCl concentration/g I-' Fig.6 Use of an internal standard to correct for signal suppres- sion caused by NaCI A 121Sb:1151n signal; and B,l2'Sb signal solutions with a carbon concentration ranging from 0.5 to 35 g 1-l were analysed. Serum contains approximately 40 g 1-1 of carbon. It appears from Fig. 2 that the indium signal remains fairly constant as a function of the carbon concentration up to about 25 g 1-l of the latter. This suggests that organic compounds up to this concentration have virtually no influence on the analyte signal. The decrease in signal at concentrations above 25 g 1-* is probably due to a too high solids concentration. It is clear that for 5-fold diluted serum the influence of the proteins will be minimal. For easily ionized elements the situation is completely different as can be seen from Fig.3. A 9 g 1-1 concentration of NaCl is equivalent to the total cation concentration of human serum. Here a strong suppression effect is noted. The same trend was observed for other elements but the suppression differed significantly as shown in Fig. 4. For 4 g 1-l of NaCl the suppression increases with increasing mass number from 33% for Li to 56% for U. Fig. 5 shows the results of measurements of solutions with various NaCl concentrations containing a constant concentration of indium. After cleaning of the sample introduction system for 2 min a pure indium solution with the same concentration was measured. After each measure- ment of the NaCl solution whereby the indium signal was suppressed the l151n+ signal returned to its original value.Of course in order to produce accurate results a method must be developed to correct for the matrix effect. The method most often applied is based on the use of an internal standard to each solution the same amount of a given element is added and the signal of the analyte is divided by that of the internal standard. Fig. 6 illustrates the effective- ness of this method. It appears that after division by theJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 783 1151n+ ion signal (internal standard) the 12’Sb+ signal is independent of the NaCl concentration. However as the suppression by NaCl is mass dependent (Fig. 4) it is obvious that not every element can be used as an internal standard and several such internal standards over the mass range must be used.In general four internal standards 9Be at low mass 59C0 for transition elements IIsIn at medium mass and 205Tl at high mass were used. To check the accuracy that can be achieved in this way a multi-element standard solution (each element at 100 pg 1 - I ) was added to 5-fold diluted serum. For each element the ‘recovery’ was determined using the original serum solution as the blank and the multi-element solution as a standard. Table 2 summarizes the results the experimental recoveries range from 98.2 to 103.2% which is acceptable in view of the experimental uncertainties. The use of a suitable internal standard with a mass number close to that of the analyte element thus corrects accurately for matrix effects with human serum. Standard additions is also an accurate method that has been applied occa~ionally.~ Examples of the Determination of Various Elements As it is impossible to deal with interferences from poly- atomic ions for every element of interest only Zn B Sn and Mo are discussed.The purpose is to show that for low concentrations a judicious selection of the analyte isotope is of prime importance. In addition it is shown that for ultra- trace concentrations of some elements in the presence of high concentrations of possible interfering elements many more spectral interferences may occur than those com- monly described in the literature (isobaric interferences interferences from M2+ interferences from polyatomic ions produced from the argon gas the solution or the matrix e.g. ArCl+ C10+ and MO+).In order to check the accuracy of the results use was made of a ‘second-generation biological reference material (Human Serum)’ certified for several trace elements by Versieck et al.,5 which will be referred to as the reference serum. Determination of zinc Zinc has five stable isotopes 64Zn (48.6%) 66Zn (27.9%) 67Zn (4.loh) 68Zn (18.8%) and ’OZn (0.60%). The determina- tion of zinc in human serum is complicated mainly by interference from sulfur-containing polyatomic ions with the major zinc isotopes (Table 3). The other spectral interferences [from 64(CaO)+ and 64(P02H)+ with ‘j4Zn+ and from 67(C102)+ with 67Zn+] are fairly unimportant. From the apparent zinc concentrations at a given sulfur concentration it appears as would be expected from the Table 2 Results of ‘recovery’ experiments Nuclide Internal standard 7Li (92.5%) 9Be 1°B (20%) 9Be ‘j9Ga (60.1 Yo) 59c0 73Ge (7.8%) 59c0 85Rb (72.2%) 1151n 88Sr (82.6%) 1l51n 9 8 ~ 0 (24.1%) 1151n ll1Cd ( 1 2.8%) ll51n 120Sn (32.6%) ll51n I2ISb (57.3%) l151n 1271 (100%) ll51n 133cs ( 1 00%) 1151n 138Ba (7 1.7Oh) 1151n 202Hg (29.8%) 2 0 5 ~ 1 208Pb (52.4%) 205TI 209Bi ( 100%) 205TI Recovery (O/O) 102.6k2.7 99.6 2 2.5 103.1 k2.1 98.22 1.7 103.2 f 2.7 100.4f 1.3 101.Ok 1.4 99.6 f 2.5 98.7 f 2.6 101.4k 1.3 101.22 1.1 99.4 f 0.8 100.8 f 1.9 1 02.0 f 2.1 100.2 f 0.9 99.2 f 2.0 Table 3 Interferences of polyatomic ions containing sulfur with the determination of zinc Interfering polyatomic Apparent Zn isotope ion concentration*/pg I-’ 64Zn 32Sl60l60 500 66Zn 34S160160 44 67Zn 34S160160H 23 68Zn 36s 1 6 0 1 6 0 3 33S160160H 32s 1 6 0 I 8 0 32Sl60180H 34s 1 6 0 1 8 0 *Apparent concentration in a solution containing 1 g I-’ of sulfur.Table 4 Results for zinc (ug g-l) in reference serum 642n 66Zn 68Zn Dilution (corrected 65%) (corrected 6%) 5-fold 10.37+0.72* 9.54k0.17” 9.59?0.32* I 0-fold 12.2 f 1 .o* 10.0+ 1.1* 9.76 f 0.43* 5O-fold 10.12 -+ 0.83* 9.33?0.46* 9.64+0.54* Certified value - 9.6 f 0.2 - *Mean values and 95% confidence limits of results on four different samples of reference serum. isotopic abundances of the relevant isotopes that 68Zn is the most suitable isotope in order to keep interference from sulfur to the minimum. The apparent zinc concentrations (64Zn 570 pg 1-I; 66Zn 54 pg l-l 68Zn 3.7 pg 1 - I ) can be compared with the zinc concentration in serum (872 pg 1 - I for the reference serum); for ‘j8Zn this contribution amounts to approximately 0.4% and can therefore be neglected.The results for the reference serum (Table 4) confirmed this. For 68Zn 5- 10- and 50-fold diluted serum gave results in good agreement with the certified value. Results obtained via 64Zn and 66Zn and using a blank solution with the same sulfur concentration as serum are also given the correction is approximately 65% for 64Zn and 6% for 66Zn. For ‘j4Zn clearly less precise results were obtained probably owing to the importance of the correction; for 66Zn the agreement with the certified value was acceptable. Determination of boron Boron has two isotopes I0B (20%) and IlB (80%). When IIB is used a problem occurs because at the normal resolution of the quadrupole mass spectrometer the IIB peak is not separated from the immense I2C peak with the high carbon concentrations found in diluted serum.The situation could be improved by destruction of the organic material by acid digestion with HN03 or HN03-HC104 and by increasing the resolution of the quadrupole. This resulted however in a higher blank (from the HC104) and in a lower sensitivity (owing to the higher resolution) so that it was not advisable to use IlB. Therefore 1°B was used for the determinations. For the reference serum a value of 227 ng g-I with a standard deviation of 18 ng g-l was obtained. Determination of molybden um Molybdenum has seven stable isotopes 92Mo ( 14.8%) 9 4 M ~ (9.35%) 9 5 M ~ (15.9%) 9 6 M ~ (16.7%) 9 7 M ~ (9.6%) 98Mo (24.1%) and IooMo (9.6%).As can be seen from Table 5 several of these suffer interference from potassium as a matrix element (concentration in human serum = 166 mg 1-I). In addition bromine interferes with the determina- tion of molybdenum as shown in Fig. 7. The increase in the784 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 Table 5 Interferences of polyatomic ions containing potassium with the determination of molybdenum Table 7 Results for tin (ng g-l) in reference serum. Literature values 10k2.6 ng g-' (NAA6); 7.6k 1.4 ng g-' (ICP-MSs); 7.96 k 0.97 ng g-l (NAA7); 8.38 k 0.48 ng g-I (NAA7) Interfering polyatomic Apparent Mo isotope ions concentration*lpg I-' 9 4 ~ 0 39K39K160 4.0 9 5 ~ 0 40Ar39Kl60 38 9 6 M ~ 39K4 1 K 1 6 0 1 .o 9 7 ~ 0 4 o ~ P ~ 1 6 0 9.5 * Apparent concentration in a solution containing 1 p g I-' of potassium.0 1 2 3 4 5 Br concentration/mg I-' Fig. 7 Apparent Mo concentration at A mlz 95 and €3 mlz 97 as a function of Br concentration apparent concentration which is a linear function of the bromine concentration can be attributed to the formation of BrO+ 79Br160+ at rnlz 95 and 81Br160+ at mlz 97. The interference of 79Br170+ and 81Br170+ at mlz 96 and 98 could not be detected for the bromine concentrations in serum. The determination of molybdenum can therefore be carried out using the 9 4 M ~ 9 8 M ~ and looMo isotopes and 9 8 M ~ was selected because it has the highest abundance. Experiments showed that under optimum conditions the blank for molybdenum ranged from 0.01 to 0.03 pg 1-L and is mainly due to the continuous background found over the spectrum.The corresponding detection limit (taking account of the 5-fold dilution) was 0.04 pg 1-1 (or 0.44 ng g-l in lyophilized serum). Table 6 gives results for the reference serum which were obtained on lyophilized (the reference serum) and on liquid serum which had been conserved deep-frozen. The results are in good agreement with the certified value (7.5k0.8 ng g-l) and the relative standard deviation (RSD) ranges from 8.3 to 15.3%. This is mainly due to the relatively low concentration so that the contribution of the background is relatively important. For the certification only results from NAA were available viz. 7.64 f 1.1 I and 7.04 3- 1.10 ng g-l respectively.A literature search showed also that apart from an occasional value obtained by ETAAS only results from NAA have been reported for molybdenum in human serum. Table 6 Results for molybdenum (ng g-l) in reference serum. Certified valueS = 7.5 f 0.8 ng g-' Lyophilized serum* Liquid serum* 6.89 (0.69) 6.90 (0.81) 8.06 (0.73) 7.82 (0.65) 7.63 (0.81) 6.89 (0.81) 7.46 (0.68) 5.87 (0.90) 7.5 1 & 0.77t 6.9 f 1.37 * Standard deviation in parentheses (n = 5). 7 95% confidence limits. Sample 1 lssn* 12OSn* Lyophilized serum 9.97 (0.51) 9.88 (0.93) 11.3 (1.1) 8.84 (0.30) 10.81 (0.67) 8.93 (0.47) 9.71 (0.46) 9.92 _+ 0.83t 9.65 (0.46) 10.38 (0.61) 10.90 (0.90) 8.69 (0.91) 10.83 (0.77) 8.67 (0.45) 9.30 (0.44) 9.77 _+ 0.887 Liquid serum 11.58 (0.93) 10.69 (0.55) 9.67 (0.66) 9.38 (0.31) 11.67 (0.54) 10.32 (0.78) 11.3 (1.1) 11.94 (0.49) 11.1 2 1.57 10.6 k 1.87 * Standard deviations in parentheses (n = 5).7 95% confidence limits. 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Sn concentrationlpg I-' Fig. 8 Tin concentration in human serum Determination oftin Tin has ten stable isotopes ll2Sn (0.97%) II4Sn (0.65%) llsSn (0.360//) Il6Sn (14.5%) Il7Sn (7.7%) l18Sn (24.2%) lI9Sn (8.6%) lzoSn (32.6%) 122Sn (4.6%) and Iz4Sn (5.8%). For all these isotopes isobaric interferences with Cd In and Te occur except for II8Sn and I2OSn therefore only these two isotopes were used for the determination of tin in serum. Under optimum conditions and taking into account the 5-fold dilution for both isotopes a detection limit of 0.05 pg 1-l of tin (corresponding to 0.55 ng g-' in lyophilized serum) was obtained with a blank corresponding to 0.02-0.06 ,ug 1-' of tin.Table 7 summarizes the results for the reference serum via 5-fold dilution and using indium as internal standard. The results obtained using both nuclides are in good agreement and the results for the liquid and lyophilized serum do not differ significantly. The RSD ranged from 3 to 10% and the blank contribu- tion ranged from 10 to 25% of the signal. The results obtained compare well with those obtained by other investigators Xilei et aL6 reported (NAA) lo? 2.6 ng g-I and Versieck and Vanballenberghe7 7.96 k 0.97 and 8.38 -t 0.48 ng g-l. Baumann8 obtained (ICP-MS) 7.6 -t I .4 ng g.-l. In view of the very low concentration these values are in excellent agreement with the results obtained here.The results for tin in sera from six female and six male healthy subjects are shown in Fig. 8. The average was 1.02 pg 1-' with a standard deviation of 0.26 pg l-l which is much lower than the ranges published previously.JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 785 Table 8 Results for trace and ultra-trace elements in second generation reference serum obtained after measurement of a 5-fold diluted reconstituted solution. Results expressed in ng g-l or pg g-' of freeze-dried sample Isotope measured '.Li 10B 24Mg 54Fe 65CU 68Zn 79Br 85Rb 88Sr 9 8 M ~ lllCd lI8Sn 12'Sb 133cs l j8Ba 200Hg 208Pb ( 100 x diluted) 1271 209Bi Result obtained* 15.04 k 0.39 ng g-I 227-1- 18 ng g-' * Means k 95% confidence limits (n= 5).t Units as in previous column. 188.1 k8.7 pg g-l 25.3 -1- 1.9 pg g-l 10.78 -1-0.22 pg g-l 9.59 k0.32 pg g-I 47.5 -1- 1 .o pg g-' I .69 -1- 0.029 pg g-l 0.2740 k0.0066 pg g-l 7.51 20.77 ng g-l 2.23 k 0.6 1 ng g-' 9.92 2 0.83 ng g-l 0.87 k 0.29 ng g-I 0.7 I0 k 0.048 pg g-' 10.20k0.79 ng g-' 11.1 k3.1 ng g-l 6.49 k0.89 ng g-l 46.3 k4.6 ng g-' 0.69 2 0.1 1 ng g-' Certified or literature value? 19.3 (ref. 8); 14.8 (ref. 12) 222 (ref. 12) 180+ 10 (ref. 12) 25.9 k 1.5 11.1 20.4 9.6 5 0.2 48.8 k 3.8 1.85 k 0.33 0.352 (ref. 6); 0.244 (ref. 4) 7.5 ~t 0.8 10 (ref. 6); 7.6 (ref. 8); 8.0 (ref. 7); 8.4 (ref. 7) 0.25 5 0.15 (ref. 6) 10.0 -+ 2.3 6.6 k 0.4 2.0 (1.7-2.5) - - Analysis of Reference Serum Table 8 summarizes the results obtained on a 5-fold diluted reconstituted solution of the reference serum.The nuclides measured are given together with the analytical results expressed in ng g-l or pg g-l of the original freeze-dried material with the 95% confidence limits. The results are compared with the certified values or with values obtained by other techniques. For nine trace elements (Fe Cu Zn Br Rb Mo Cd Cs and Hg) the results were in good agreement with the certified value for five other elements (Li B Mg Sr and Sn) there was good agreement with values from the literature for Sb the agreement with one literature value is not satisfactory and for four other elements (I Ba Pb and Bi) no comparison with literature data was possible. Attempts were also made to determine other elements but were unsuccessful for the reasons mentioned in paren- theses A1 (interference from l2CI5N and I3Cl4N) Si (poly- atomic ions containing C N and 0) Sc [interference of 45(C02H)+] Ti (polyatomic interferences) V (interference of ClO) Cr (interferences from Arc and ClO) Mn (interference from C10 and KO) Ni (interference from CaO Table 9 Results for National Institute of Standards and Techno- logy (NIST) Standard Reference Material (SRM) 909 (Human Serum) Certified Element Nuclide ICP-MS* value Li/mmol 1-' 'Li 1.68 (0.04) 1.61 (1.70) Mg/mmol I - l 24Mg 1.20 (0.02) 1.18-1.26 Pb/nmol I-' 208Pb 91.6 (2.5) 87- 109 * Standard deviations in parentheses (n = 5).and NaCl) As (interference from ArC1) and Se (interference from Ar ArCl and SO3). Of course hydride generation can be used for example to separate As and Se (e.g.from C1) in order to determine these elements in biological materials. Buckley et aL9 determined Se in several biological reference materials using a hydride generation sample introduction system. In order to check further the accuracy of the method a National Institute of Standards and Technology (NIST) Table 10 Results for lithium (ng g-I) in three biological reference materials Material SRM 1549 Non-Fat Milk SRM 1548 Total Diet Powder SRM 1845 Cholesterol in Whole Egg Powder ICP-MS* Other results 8.7 (1.2) 10.0 (1.9) 9.65 1.8 (NA-MS'O) 50.2 (2.1) 49t 48.2 (2.0) 48.6 It 0.5 (NA-MS'O) 51.4 (1.1) 49.2 (0.6) 49.8 k 2.24 73.6 (2.4) 71.4 (0.7) 70.2 (1.4) 72.2 k 2.5$ 73.4 (1.7) 78.2 k 1.2 (NA-MS'O) * Standard deviation in parentheses (n= 5).t Indicative value. $ 95% confidence limits.786 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 ~~ Table 11 Results for boron (ng g-*) in three biological reference materials Material SRM 1567a Wheat Flour SRM 1577a Bovine Liver SRM 1548 Total Diet * Standard deviations in parentheses (n=?). t PGAA= neutron-capture prompt pray activation analysis. $ Indicative value. 4 95% confidence limits. ICP-MS* Other results 610 (30) 580 k 20 (NA-MS'O) 530 (40) 950 (30) 1040k 130 (PGAAt") 860 (60) 590 f 80 (NA-MS'O) 2668 (21) 2500$ 2688 (5) 2685 k 409 2700 (17) 24 10 f 50 (NA-MS'O) 26 10 f 120 (PGAAt") Standard Reference Material (SRM) SRM 909 Human Serum was also analysed for Li Mg and Pb. Table 9 shows that the results (obtained on 50-fold diluted reconstituted samples for Li and Mg and on Sfold diluted samples for Pb) are in good agreement with the certified values.Other Biological Samples It is impossible to discuss in this paper the application of ICP-MS to all types of biological samples. Usually solid biological samples are first dissolved by an appropriate digestion procedure. Tables 10 and 11 give some results obtained for Li and B in three different biological reference materials. The samples were digested in closed poly- (tetrafluoroethylene) (perfluoroalkoxy resin) vessels with concentrated HN03 using a domestic microwave oven. An amount of 400 mg of sample and 2.5 ml of nitric acid were heated using the following programme 8 min at 20°/0 8 min at 40% and 4 min at 60% of the maximum power (700 W).This sequence was repeated twice the digest was diluted to 25 ml and Be was added as internal standard. In general the agreement with the other technique(s) cited was sat isfactory . Grateful acknowledgement is made to J. Versieck for his interest in this work and for providing the serum reference material. 1 2 3 4 5 6 7 8 9 10 11 12 References Iyengar G. V. Elemental Analysis of Biological Systems. Volume 1. Biomedical Environmental Compositional and Methodological Aspects of Trace Elements CRC Press Boca Raton FL 1989. Versieck J. and Cornelis R. Trace Elements in Human Plasma or Serum CRC Press Boca Raton FL 1989. Vanhoe H. Vandecasteele C. Versieck J. and Dams R. Anal. Chem. 1989 61 1851. Vandecasteele C. Vanhoe H. Dams R. Vanballenberghe L. Wittoek A. and Versieck J. Talanta 1990 37 819. Versieck J. Vanballenberghe L. De Kesel A. Hoste J. Wallaeys B. Vandenhaute J. Baeck N. Steyaert H. Byrne A. R. and Sunderman F. W. Anal. Chim. Acta 1988,204,63. Xilei L. Van Renterghem D. Cornelis R. and Mees L. Anal. Chim. Acta 1988 211 231. Versieck J. and Vanballenberghe L. Anal. Chem. 1991 63 1143. Baumann H. personal communication 1 988. Buckley W. T. Budac J. J. Godfrey D. V. and Koenig K. M. Anal. Chem. 1992 64 724. Iyengar G. V. Clarke W. B. and Downing R. G. Fresenius' J. Anal. Chem. 1990 338 562. Anderson D. L. Cunningham W. C. and Mackey E. A. Fresenius' J. Anal. Chem. 1990 338 554. Abou-Shakna F. R. personal communication 1990. Paper 3/00268C Received January 18 1993 Accepted March 4 1993

ISSN:0267-9477    

DOI:10.1039/JA9930800781

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 787 Potential of Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry for Trace Metal Speciation* Invited Lecture Nohora P. Vela and Joseph A. Carusof Department of Chemistry University of Cincinnati Cincinnati OH 45221 -01 72 USA Liquid chromatography (LC) and supercritical fluid chromatography (SFC) coupled with plasma mass spectrometry for ultra-trace level detection of metal-containing compounds are discussed. The compatibility of liquid and supercritical fluid flow rates with the plasma allows real-time chromatograms to be obtained. Different LC modes including reversed phase ion exchange and size exclusion have been used in the separation of metal-containing species and some of these applications are discussed in this paper.Studies to date have developed potential methods for arsenic mercury lead tin and chromium speciation. Sub-ng to pg detection is available with LC sample introduction into the plasma. Chromatographic methods which introduce samples as gases such as SFC provide the best levels of detection usually in the pg to sub-pg range. Keywords Trace metal speciation; plasma source mass spectrometry; liquid chromatography; supercritical fluid Chromatography Improvements in instrumentation performance and design plus continually developing methods have responded to the demand for more sensitive and reliable techniques in trace metal speciation. It is known that the determination of the total metal content in a sample is not always sufficient thereby requiring metal speciation.Metal speciation refers to the identification and quantification of organometallic state or oxidation state in a particular sample. Variations in the chemical form define the toxicity or essentiality of the analyte. Since the final goal in methods development for trace metal analysis is to analyse ‘real samples’ including for example waters biological fluids and foods several precautions must be taken and considerations made. Firstly the technique should provide sufficient sensitivity and selectivity to separate and detect the analytes of interest present in a complex matrix sample eliminating or minim- izing possible interferences. Secondly the method should require minimum sample handling so that the original species present in the sample are preserved.Ideally the technique must be applicable to different types of samples. Trace metal speciation is achieved through the combina- tion of two different techniques one providing an efficient and reliable separation procedure and the other detection and quantification. Several chromatographic procedures are available but the most commonly used for the separa- tion of metal containing species are gas chromatography (GC) and liquid chromatography (LC). Supercritical fluid chromatography (SFC) provides an alternative to GC and LC and has also been used for the separation of organome- tallics. Inductively coupled plasma atomic emission spec- trometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) are two different and sensitive methods used in trace metal speciation.The main advan- tages of ICP-MS over ICP-AES are lower limits of detection (sub-ng to sub-pg levels) wide linear ranges and isotope analysis capability with precisions expressed as relative standard deviation (RSD) of 0.1-5%. This paper describes the potential for LC and SFC coupled with ICP-MS for trace metal speciation. Several laboratories have developed methods for the speciation of organometallics containing arsenic tin lead mercury cadmium and gold in a variety of samples. A review of different LC modes is given * Presented at the 1993 European Winter Conference on Plasma t To whom correspondence should be addressed. Spectrochemistry Granada Spain January 10-1 5 1993. including reversed phase ion pair ion exchange and size exclusion that have been used in the separation of metals and organometallics as well as capillary SFC with particu- lar reference to their interfacing with ICP-MS.Trace Metal Speciation Toxicity of Metal Containing Compounds There is no general rule or trend that relates toxicity with oxidation state or chemical form and number of substitu- ents linked to the central atom. Arsenic containing com- pounds are a good example to illustrate the need for elemental speciation. A decreasing order of toxicity is as follows arsenite (AslI1) arsenate (AsV) monomethylarso- nate (MMA) and dimethylarsinate (DMA). Lethal doses LD50 (rats) for these compounds are 1.5 5 50 and 500 mg kg-l respectively. Other organoarsenic compounds such as arsenobetaine (ASB) and arsenocholine (ASC) have been found to be non-toxic for Toxicity of organotin compounds presents a different picture.Tetra- and tri-organotin compounds have similar toxicities and they are the most hazardous. A decrease in the number of substituents is related to a reduction in t ~ x i c i t y ~ . ~ and tin is in fact one of the essential trace elements6 Other important factors in the toxicity of organotin compounds are the type of alkyl group those containing ethyl methyl propyl or butyl phenyl and octyl groups are listed here in decreasing order of toxi~ity.~J Although the traditional application of alkyllead com- pounds as gasoline additives has declined in the USA the presence of these compounds in the environment is still of concern. Tetraethyllead tetramethyllead and the three mixed methylethyllead species are the most common.Degradation products of tri- and di-alkyllead have also been found in environmental sample^.^*^*^ Another interesting metal that has gained attention in metal speciation is chromium as the oxidation state clearly defines the extent of toxicity Cr1I1 is essential in human nutrition whereas CrV1 is toxic or a precursor to toxic Liquid Chromatography Modes The popularity of LC in the speciation of organometallics is well recognized. This separation technique offers the possibility to separate ionic polar and non-polar com-788 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 pounds and extensive efforts have been directed towards column technology. Reversed-phase liquid chromatograpy (RPLC) is the most popular separation mode in LC.9 Separation is obtained by partition of the analyte between a non-polar stationary phase and a polar mobile phase.Usually mobile phases are aqueous mixtures of methanol acetonitrile or tetrahydrofuran. Use of a buffer solution control of the pH and addition of salts are the parameters evaluated to optimize an RPLC method. Reversed-phase ion-pair chro- matography uses the same type of columns and mobile phases as RPLC the only difference being that a counter ion is added to the mobile phase. The counter ion or ion- pair (IP) reagent is of opposite charge to the sample molecule. One option in IPLC is the use of detergents as counter ions.9 This is known as micellar liquid chromato- grapy and it has been used in the separation of metal- containing compounds.1° Ion-exchange chromatograpy (IEC) is applied to the separation of ionic and non-ionic compounds complex ions and neutral species.Non-polar compounds can be resolved in IEC by the formation of ionic complexes or by ligand- exchange reactions. The extent of ionization sample retention and selectivity are controlled by variations in pH. Mobile phases in IEC consist of a buffered aqueous salt solution with limited amounts of methanol or acetonitrile (less than 35%). Variations in column temperature (up to 60 "C) are also suggested in IEC when changes in pH and mobile phase do not improve the result^.^ One of the limitations of IEC is only moderate stability and reproduci- bility in packing materials. The use of pre-columns and guard columns and a pre-clean step for samples is required to extend the life of the column.In size-exclusion chromatography (SEC) the separation occurs according to the effective molecular size in ~olution.~ Adsorption or partition ion exchange and chemical interac- tions are minimized in SEC. Selection of the mobile phase in SEC is based on the capability to dissolve the sample the compatibility with the stationary phase and the effective- ness in eliminating or reducing interaction of the sample with the packing material. Usually the mobile phase contains a salt to eliminate adsorption mostly when unmodified siliceous packing material is used. Supercritical Fluid Chromatography A key feature of SFC is that it bridges the gap between GC and LC having the main advantage of GC that is high diffusion coefficients and LC which has good solubility properties.In this way it is possible to separate thermally labile non-volatile and high relative molecular mass com- pounds not easily separated by GC and with the advantage of shorter analysis times than LC." Temperature programming and gradient elution respec- tively are the parameters used to optimize separation conditions in GC and LC. The same variables are consi- dered in SFC with the difference that instead of gradient elution the properties of the mobile phase are changed by adding a modifier. This 'modifier' alters the solubility properties of the mobile phase and the partition coefficients of the solute between solvent and stationary phase.ll A modifier is required for the elution of compounds that are somewhat polar and have limited solubility in a non-polar mobile phase.The most widely used mobile phase is carbon dioxide. Methanol acetonitrile chloroform and even water have been employed as modifiers in SFC. Solvating power diffusion coefficients and viscosities of supercritical fluids are a function of density. Thus pressure or density programming constitutes a third variable in SFC and perhaps the most important. Simultaneously density is temperature dependent. This means that at low tempera- ture the mobile phase will have higher density and better solvating power generally yielding a more rapid elution from the column.11 Interfacing Chromatography and Plasma Mass Spectrometry The compatibility of the liquid flow rate from LC with the traditional sample introduction devices used in ICP makes it relatively easy to interface LC with ICP-MS.All that is required is a transfer line between the LC column and the nebulizer. However some peak broadening is observed but this is minimized by using narrow bore and short transfer lines. One limitation of conventional nebulization is the low analyte transport efficiency ( 1 - - 5 % - 0 ) . ~ 9 ~ 7 ~ The use of ultrasonic nebulizers in LC-ICP is a benefit (10% analyte transport efficiency) but these present considerable dead volume in the gas phase.4 Direct injection nebulization (DIN) is promising for LC-ICP-MS since it provides minimum peak broadening and almost 100% analyte transport efficiency for microbore columns with mobile phase flow rates of up to 0.5 ml Interfacing SFC with ICP-MS requires a more complex set-up.The spray chamber is removed and typically is replaced by the interface shown in Fig. 1 which has been described in a previous p~b1ication.l~ The function of the restrictor is to keep the supercritical conditions through the column and to maintain certain linear velocity (about 1 ml min-I). The frit restrictor is inserted and positioned flush with the end butting the copper tube to minimize the dead volume. A heated argon make-up gas that corresponds to the nebulizer gas flow serves as a carrier for the analyte and helps to produce a central channel in the plasma. Control of the interface temperature is required since at the tip of the restrictor the mobile phase changes from a supercritical fluid to a gas at atmospheric pressure.This process is subject to the Joule-Thomson effect and net cooling is the result." Sufficient heat must be provided to the restrictor in order to avoid cluster formation and wall condensation. Optimization of the interface temperature is recommended especially for mixtures that contain com- pounds of different v01atilities.I~ Inductively Coupled Plasma Mass Spectrometry Operating Conditions In general LC mobile phases contain organic solvents and salts in buffer solutions or as ion-pair reagents. Perform- ance of the ICP-MS instrument can deteriorate because of the instability of the plasma due to the presence of organic vapours and the deposition of salts in the nebulizer and sampling cone causing physical bl~ckage.~ Use of a water- cooled spray chamber and an increase in the r.f.power (up to I .6 kW) partially reduce the problems caused by organic s ~ l v e n t s . ~ J ~ Addition of oxygen ( 1 -3%) to the nebulizer flow is also recommended to minimize carbon deposition Copper tube I Heated zone Transfer line I connector Make-up gas Frit restrictor Column Fig. 1 Schematic diagram for the SFC-ICP-MS interface. Repro- duced from ref. 13 with permission from the American Chemical SocietyJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 789 and clogging of the sampler and skimmer with the disadvantage of significantly reducing their lifetirnes.l5 The presence of salts in the mobile phase causes short- term signal drift affects sensitivity (signal-to-noise ratio) and gives a more complex spectrum particularly for mlzt80.Nebulization of 2% nitric acid between runs tends to alleviate the inconvenience caused by the salts in the mobile phase. Recent chromatographic instrument design provides the option of metal free LC systems with the advantage of less interferences and potential contamina- tion. Finally coupling LC with ICP-MS requires com- promise conditions in order to maintain a good separation and acceptable detector performance. A recent publicationi4 demonstrated that when SFC is coupled to plasma mass spectrometry it is not necessary to modify the normal ICP-MS operating conditions. The plasma is more tolerant to the low flow rates of the carbon dioxide (less than 1 ml min-l) than to larger organic solvents flows from LC.Separation of Organometallics Using Reversed-phase Chromatography Beauchemin et a1.I6 identified ASB as the final metabolic product of arsenic in a Dogfish Muscle reference material (DORM- 1 from the National Research Council of Canada) by using a simple methanol-chloroform extraction followed by LC-ICP-MS. The mobile phase consisted of a 10 mmol 1-l sodium dodecyl sulfate solution containing 5% metha- nol and 2.5% glacial acetic acid. A CIS column was used for the separation and although three arsenic containing compounds (As*I1 AsV and MMA) co-eluted DMA and ASB were well resolved. The presence of ASB in the sample was confirmed by comparison with the LC-ICP-MS results for a spiked sample. Further confirmation was obtained by electron impact mass spectrometry (EIMS).The amount of ASB present in the sample (15.7a0.8 pg of As per g of DORM-1) corresponded to 84% of the total arsenic present in the sample. Bushee17 reported the separation of mercury containing compounds using a PicoTag c18 column with a mobile phase consisting of a 0.06 mol 1 - I ammonium acetate 3% acetonitrile and 0.005% v/v 2-mercaptoethanol. A post- column mercury cold-vapour generation was included in the system which improved the sensitivity when compared with LC-ICP-MS. The chromatogram obtained for the separation of different organomercury compounds is shown in Fig. 2. The method was verified by analysing several spiked solutions as well as a National Institute of Standards and Technology (NIST) Reference Material (RM) (RM50 Albacore Tuna) that contains methylmercury. Thimerosal (sodium ethylmercurithiosalicylate) was also determined and comparable results were obtained by direct solution nebulization and LC-ICP-MS mercury concentrations as low as 0.004% being detected.Detection limits for the organomercury compounds ranged from 7 to 20 ppb using LC-ICP-MS and from 0.6 to 1.2 ppb using LC-cold vapour A more detailed paper concerning the separation and detection of thimerosal has been published by Bushee et a1.18 Samples of vaccines and toxoids (influenza virus vaccine and tetanus toxoid) were analysed for their mercury content by flow injection (F1)-ICP-MS and compared with the results obtained by LC-ICP-MS. The results indicated that the organomercury present in the sample was fully recovered after the LC runs.Column and chromatographic conditions for this work had been described previou~ly.~~ Reversed-phase LC was investigated for the separation of inorganic lead and trimethyllead.I9 An Econosphere column and a mobile phase consisting of 0.1 mol 1-' ammonium acetate and 30% methanol at a pH of 4.6 ICP-MS. I 1 0 4 8 12 16 Ti me/m i n Fig. 2 LC-cold vapour ICP-MS chromatogram of 1 methylmer- cury acetate; 2 mercury(x1) chloride; and 3 ethylmercury at the 13 ng ml-' mercury level. Reproduced from ref. 17 with permission from The Royal Society of Chemistry provided the separation between Pb2+ and trimethyllead. Triethyllead chloride eluted in reasonable time but tri- phenyllead chloride was highly retained in the column. Absolute detection limits for inorganic lead trimethyllead and triethyllead were 32 25 and 87 pg respectively.Reversed- p hase ion -pair chromatography Non-metallic anionic compounds containing phosphorus and sulfur have been separated using tetraalkylammonium salts as the ion-pairing reagents.20 The chromatogram obtained for the separation of inorganic phosphates is given in Fig. 3. Some adjustments in mobile phase composition flow rate and sample pH were required to apply the technique to the separation of adenosine phosphates. This paper by Jiang and Houk also described the detection of sulfur monitoring at mlz 34 since at mlz 32 a high background signal is present. It is important to point out that the detection limits obtained with this technique are comparable to those obtained with LC-DIN-ICP-AES despite the low abundance (4.2%) isotope. Inorganic sul- fates and amino acids were used as samples to demonstrate l4 1 I A 0 2 4 6 Time/min Fig.3 Reversed phase ion-pair chromatography with ICP-MS as the phosphorus selective detector in the separation of phosphates A orthophosphate; B pyrophosphate; and C tripolyphosphate. Reproduced from ref. 20 with permission from Pergamon Press7 90 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 Table 1 Detection limits for compounds speciated by different reversed-phase LC modes and ICP-MS detection HPLC mode* Detection limit/ Element RP IP MLC Pg As Hg Pb Pb Sn Hg Pb S P Sn x x - x - - x x - - x - - x - - x - - x - - x - - x - X - - 50-300 7-20 ppb 25-1 59 140-3900 400- 1000 7 0.2 7000 400-4000 26- 126 Reference Beauchemin and co-workers refs. 16 and 21 Bushee ref.17 AL-Rasdan et al. ref. 19 AL-Rasdan et al. ref. 22 Suyani et af. ref. 15 Shum et af. ref. 12 Shum et al. ref. 12 Jiang and Houk ref. 20 Jiang and Houk ref. 20 Suyani et al. ref. 10 * RP reversed phase; IP ion pair; and MLC micellar liquid chromatography. the capability of LC-ICP-MS for their separation and detect ion. A comparison of anion pairing and cation pairing in the separation of As"' AsV MMA and DMA was presented by Beauchemin et Baseline resolution for the previously mentioned arsenic containing compounds was obtained by anion-pair chromatography. However the presence of a matrix containing lithium or iron compromises the chroma- tographic separation showing that the particular conditions were not convenient for the analysis of real samples.Cation pairing provided good results in the determination of DMA and ASB present in biological samples with high salt concentrations. Absolute detection limits for arsenic species varied between 50 and 300 pg. Improvements of three orders of magnitude in detection limits for tin were reported by Suyani et a1.,I5 when ICP-MS was compared with ICP-AES under the same chromatogra- phic conditions. The column used was a Spherisorb ODs-2 CIS and the mobile phase prepared in 80+ 19+ 1 metha- nol+water+acetic acid at pH 3.00 contained 4 mmol l-l sodium pentane sulfonate. Different trialkyltin chlorides were separated and the chromatogram is shown in Fig. 4. Direct solution nebulization of tin in the LC eluents gave detection limits of 0.1 ppb whereas with chromatography they are 20 times higher.Accumulation from tin in the ion- pair column is evident from the relatively high background. Also tin was detected in the solvent front when a blank was injected. The absolute detection limits are listed in Table 1. Speciation of lead containing compounds has been described by AL-Rashdan et a1.I9 Triorganolead com- A I I 1 I 0 400 800 1200 1600 Retention time x 03s Fig. 4 Ion-pair chromatogram with ICP-MS detection for tin containing species identified as A tin contaminant; B trimethyltin chloride; C triphenyltin acetate; and D tributyltin chloride. Sample size 6 ng (51 pmol). Reproduced from ref. 15 with permission from Preston Publications a Division of Preston Industries pounds were resolved by ion-pair chromatography using a Spherisorb ODs-2 c18 column with a mobile phase contain- ing 4 mmol 1-' sodium pentane sulfonate and 70% methanol at a pH of 3.Baseline resolution for trimethyl- lead triethyllead and triphenyllead chlorides was observed. However a front shoulder on the trimethyllead peak identified as inorganic lead was also present. Detection limits for trialkyllead compounds using ion pairing ranged from 59 to 159 pg. A recent publication by Shum et a1.12 described the use of ion-pair chromatography for the speciation of organomer- cury and organolead compounds. A metal free LC system consisting of a bioclean microflow pump head and a 5 cm long 1.6 mm i d . PEEK column packed with reversed- phase CIS material was employed. A narrow bore polysil tube (50 pm i.d.and 5 cm long) connects the analytical column with the nebulizer. The sample was introduced into the plasma using a direct injection nebulizer. The mobile phase giving optimum results contained 5 mmol 1-l ammonium pentanesulfonate in 20 + 80 vlv acetonitrile- water with a flow rate of 100 pl min-l. A Perkin-Elmer SCIEX instrument was used for data acquisition monitor- ing at rnlz 202 for Hg+ and mlz 208 for Pb+. In Fig. 5 the chromatogram obtained for the separation of species containing lead and mercury is presented. Detection limits for mercury- and lead-containing compounds were of the order of 7 and 0.2 pg respectively independent of the specific chemical form. The technique was validated using 8 1 0 1 2 3 4 5 6 Retention time/min Fig.5 Separation of two alkyllead and three organomercury species using ion-pair chromatography and ICP-MS detection. Reproduced from ref. 12 with permission from The American Chemical SocietyJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 79 1 Retention ti me/m i n Fig. 6 HPLC-ICP-MS of 5 ppm of A Pbii; B triethyl- lead chloride; C triphenyllead chloride; and D tetraethyllead. Chromatographic conditions Nucleosi! CIS column; mobile phase 8 mmol 1-1 PIC-B5 at pH 3; and gradient elution 40-90% methanol over 10 min held at 90% methanol for 20 min. Flow rate 1 ml min-I. Reproduced from ref. 22 with permission from The Royal Society of Chemistry an NIST SRM 2670 Freeze-Dried Urine for Lead Specia- tion.The sample contained only inorganic lead and the results showed good agreement with the certified value. A 24 h urine specimen was analysed for the presence of mercury and demonstrated signal suppression for methyl- mercury and ethylmercury due to the presence of sodium in the matrix. However in the same sample no signal suppression was observed for mercury(I1). Gradient elution HPLC was applied by AL-Rashdan et aLzz to separate in one run inorganic lead ionic alkyllead and tetraalkyllead compounds. Methanol concentration was changed from 40 to 90% over a time period of 10 min. Under these conditions the plasma is stable with minimum reflected power. Effects of ion-pair concentration and pH on the separation of lead-containing compounds were evaluated in this paper.A typical chromatogram is illustrated in Fig. 6. Loss in sensitivity owing to the high organic solvent concentration (90% methanol) was observed for tetraethyllead which elutes last in the chroma- togram. The absolute detection limit for this component was 3.9 ng. For inorganic lead triethyllead chloride and triphenyllead acetate they are 0.37 0.14 and 0.17 ng respectively. Absolute detection limits were calculated considering a 50 pl sample injection. The NIST SRM 2715 Lead in Reference Fuel that contains tetraalkyllead was used to verify the technique.22 The results indicated that direct solution nebulization and LC sample introduction to ICP-MS show good agreement with the certified value. The detection limits are summarized in Table 1 for different metal containing species that are separated using different reversed-phase modes and plasma mass spectro- metric detection.Micellar liquid chromatography Micellar liquid chromatography coupled to ICP-MS has been used in the determination of triorganotin com- pounds.'O Surfactants of different polarity including so- dium dodecyl sulfate (SDS negatively charged) dodecyltri- methylammonium bromide (DTAB positively charged) and polyoxyethylene(23)lauryl ether (Brij-35 non-ionic) were tested. Satisfactory chromatographic results were obtained only with SDS at a concentration of 0.1 mol 1 - I . The mobile phase also contained 3% v/v acetic acid and 3% v/v propanol. Using the same C18 column but 0.05 mol 1-' SDS and 5 mmol I - ' KF it was possible to separate mono- di- and tri-methyltin species.Detection limits for trimethyl- tin chloride triethyltin chloride and tripropyltin chloride were 25 51 and 1 I 1 pg respectively. Similar detection limits were obtained for monomethyltin trichloride dime- thyltin dichloride and trimethyltin chloride (46,26 and 126 pg respectively). The RSD for ten 100 pl injections containing 4 ng of tin varied from 1.3 to 1.9% with a 0.1 mol 1-' SDS mobile phase and from 3.4 to 4.8% with a 0.02 mol 1-1 SDS concentration. Metal Speciation by Ion-exchange Chromatography Suzuki et al.23 described the use of ion-exchange chromato- graphy in the determination of chloride and bromide present as impurities in methamphetamine. Previous re- sults obtained by neutron activation analysis and con- firmed using ICP-MS indicated that the samples of meth- amphetamine also contained sodium palladium and bar- ium.A paper published by Suyani et a l l S referred to the separation of triorganotin compounds using an ion-ex- change column (Adsorbosphere SCX). The mobile phase composition was 0. I mol 1-1 ammonium acetate in 85% v/v methanol + water. Tributyltin chloride triphenyltin acetate and trimethyltin chloride were completely resolved giving a linear response over three orders of magnitude. These compared sensitivity using ion pairing and ion exchange for the separation of the same organotin com- pounds and even with the lower background signal that is obtained in the ion-exchange mode no improvement in sensitivity was achieved. Method development in arsenic speciation by Beauche- min et al.*I included not only ion pairing but also anion- exchange columns. Two different anion-exchange columns were used [Radial-Pak (SAX) and PRP-X 1001 and a mobile phase consisting of phosphate buffers at pH values of 7 and 8.Arsenic containing compounds considered in this work included As"' AsV MMA and DMA and under different chromatographic conditions no baseline resolu- tion was obtained for all species. However the buffering capacity of the mobile phase allowed the injection of a strong acid matrix with minor modifications in retention times. Heitkemper et aLz4 emphasized some of the modifica- tions required in the LC method when changing from LC-ICP-AES to LC-ICP-MS. For example it was neces- sary to decrease the buffer concentration (from 50 mmol 1-1 NH4H2P04 to 15 mmol 1-l and from 5 mmol 1-I CH3C02NH4 to 1.5 mmol l-') to prevent salt deposition and clogging of the sampling orifice.However since this new mobile phase has a lower solvent strength the analysis time was extended. This was overcome using a flow-rate programme consisting of 6 min at 1 ml min-I followed by a faster flow rate (2 ml min-I) for the remainder of the chromatogram. Arsenic compounds (As"' DMA MMA and AsV) were completely resolved using a weak anion- exchange column and the analytical figures of merit are presented in Table 2. Minor variations in detection limits were observed for As standards in aqueous solutions and in urine samples. However as indicated by the arrow in Fig. 7 the presence of chlorine in urine samples causes problems in the determination of As"'.Arsenite ion co-elutes with chloride which in the presence of argon produces the 40Ar35C1+ interference at m/z 75. Elimination of the 40Ar35C1+ interference by chromato- graphically resolving arsenic compounds and chlorine was reported by Sheppard et aLz5 The separation was achieved using a Wescan Anion/R IC column and a mobile phase containing 5 mmol 1 - I phthalic acid at a pH of 2.55. The effect of sodium chloride concentration in the separation of As"' and AsV was initially evaluated since urine samples792 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 Table 2 Detection limits and response data for arsenic species* Parameter As111 DMA MMA AsV Calibration graph data?- Absolute detection Sensitivity/counts Slope log-log data 0.972 0.975 0.988 0.992 Retention timelmin 3.7 4.7 6.9 8.5 limit for As/pg$ 38 20 44 91 5.9 11.2 5.0 2.4 0.9999 Per Pg.Correlation coefficient 0.9999 0.9999 0.9999 Standard additions data for a representative urine sample&- Absolute detection limit for As/pg$ 73 38 Sensitivitylcounts Per Pg. 4.1 7.0 Correlation coefficient 0.9976 0.9984 * Adapted from ref. 24 by permission from The Royal Society of Chemistry. t Four standards ranging in concentrations from 10 ppb to 1 ppm; sample size 50 pl. 4 Detection limit 3a background counts/slope of calibration curve. 4 Urine sample UriChem Urine Chemistry Control freeze-dried urnne; sample size 50 pl. 36 5.9 0.9982 96 3.3 0.9885 MMA DMA 0 102 204 306 408 510 Retention time/s Fig. 7 Chromatogram of a urine sample spiked with 2 ng of each arsenic species consisting of AslI1 DMA MMA and AsV.Sample size 200 pl. Mobile phase 30% methanol-15 mmol 1-l NH4H2P04-2 mmol 1-I CH3C02NH4. Flow rate 1 ml min-l for 6 min followed by 2 ml min-'. Monitoring at mlz 75. The arrow indicates interference in the determination of As111. Reproduced from ref. 24 with permission from The Royal Society of Chemistry contain about 0.9% sodium chloride. Results indicated that a 20-fold dilution of the urine samples was necessary in order to prevent overloading the column. Under these conditions baseline resolution for AslI* AsV and ArC1+ was obtained. Detection limits in urine were 3.4 4.2 and 7 ppb for AslI1 AsV and DMA respectively. Three freeze-dried urine standards were used to test the accuracy of the method. One limitation of this technique is the lack of resolution between DMA and MMA. Recently Sheppard et a1.26 investigated the use of alternative mobile phases and a gradient programme to separate arsenic species and the 4oAr35C1+ interference in a single run.Conventional argon ICP-MS and helium-argon mixed gas ICP-MS were used in the detection of arsenic- containing compounds in different samples (freeze-dried urine club soda and wine). The sensitivity was improved using a helium-argon mixed gas plasma. However the ArC1+ signal was also increased owing to the more energetic plasma. Presented in Table 3 is a comparison of the detection limits. A comparison of ICP-MS and colorimetry in the determi- nation of CrV1 has been presented by Roehl and A l f o r q ~ e .~ ~ Similar detection limits (1-2 ppb) and linearity (four decades) were calculated for both systems. Ion chromato- graphy was also employed for the separation of vanadium tungsten molybdenum and chromium in the form of their oxyanions. Kawabata et a1.** reported the separation of 14 trace rare earth elements using ion chromatography with plasma mass spectrometric detection. Detection limits ranged from 1 to 5 ppt with linear ranges from 10 ppt to 10 ppm. Size-exclusion Chromatography in the Separation of Metal Containing Species Studies of metalloproteins have been successfully accom- plished by coupling SEC and ICP-MS.29v30 The chromato- gram obtained for the separation of metallothionein and ferritin is shown in Fig. 8 with ( a ) UV detection and (b) ICP-MS monitoring at mlz 114 for cadmium.29 Mason et aL30 also determined cadmium copper and zinc in metallothionein. Size-exclusion and weak anion-exchange chromato- graphy were used in the characterization of gold-based drug metabolites present in blood samples. Some adsorption of Table 3 Analytical figures of merit for arsenic species in a 1 +4 wine matrix* Parameter As"I AsV DMA MMA Ar ICP-MS- Detection limit (ppb) 1.6 2.6 0.73 1.8 Absolute detection limit for Aslng 0.16 0.26 0.073 0.18 Linearity? 3 3 3 >2 Reproducibility RSD n= 5 (Oh) 4.5 5 4 15 He-Ar ICP-MS- Detection limit (ppb) 0.63 0.37 0.32 0.80 Absolute detection limit for Aslng 0.063 0.037 0.032 0.080 Linearity 3 3 3 3 RSD n=5 (O/O) 7 4 14 12 Reproducibility * Adapted from ref.26 with permission from The Royal Society t Linearity in orders of magnitude.of Chemistry.793 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 t W C (D e v) 9 Q t a C P W a 6 10 14 18 22 Ti me/mi n Fig. 8 Analysis of metalloproteins [ferritin (F) and metallothionein (M)] using (a) UV (254 nm) and (b) ICP-MS (*14Cd) detection. Reproduced from ref. 29 with permission from The Royal Society of Chemistry 0 2 4 6 8 10 Ti m e/m i n Fig. 9 SFC-ICP-MS chromatogram for 500 pg injection of each organotin using a 4 m column. Initial pressure 80 atm held for 2.5 min; pressure ramp 150 atm min-I; and final pressure 400 atm held for 5 min. Oven temperature 75 "C. See text for peak identification; X is an impurity. Reproduced from ref. 14 with permission from The Royal Society of Chemistry the metals in the column was established by comparison of the results obtained from calculated peak area using flow injection and peak intensities with SFC for Au Zn and Cd.31 Variations in pH buffer composition and addition of modifiers reduces but does not completely eliminate adsorption of the metals in the column.The effect of cooking and enzymic digestion on the molecular size of cadmium-binding proteins was discussed in the paper published by Crews et Three fractions with relative molecular mass ranging from 1.2 x lo6 to 6 x lo3 were found in uncooked pig. After cooking or enzyme treatment only the small relative molecular mass fraction was present. Supercritical Fluid Chromatography for Analysis of Organo- metallic Compounds The potential of plasma mass spectrometry as a detector for capillary SFC has been demonstrated by Shen et aLL3 '- I ,-......__. --._ _.-..-...._ ....-. '^."*.. _..... .-... ......... +-. ._... ~ ._....... ......I -... -... 0 2 4 6 8 10 Time/m i n Fig. 10 Time-resolved acquisition scan for tetraphenyltin (A 120Sn and B IlsSn) and tetraphenyllead (C 2osPb and D 2MPb) separated using SFC followed by ICP-MS detection. Chromatogra- phic conditions as in Fig. 9. Isotope ratios IzoSn:IIaPb actual ratio 1.373; experimental ratio 1.340; error 2.4%; and 208Pb:2MPb actual ratio 2.083 experimental ratio 1.853 error 11.0%. Repro- duced from ref. 14 with permission from The Royal Society of Chemistry Tetraorganotin compounds were separated using an SB- octyl-50 capillary c ~ l u m n .~ ~ ~ ~ ~ The addition of 2% methanol to the carbon dioxide mobile phase did not affect the stability and sensitivity of the ICP-MS in~trument.~~ Abso- lute detection limits for tetrabutyltin and tetraphenyltin were 0.18 and 0.22 pg respectively with linear responses of three decades. Vela and Caruso14 reported the speciation of tri- and tetra-organotin compounds with an SB-biphenyl-30 capil- lary column. This study described the effect of oven temperature pressure programming mobile phase compo- sition and column length on the separation of organotins. Detection limits of 0.26 0.80 0.57 and 0.20 pg were found for tetrabutyltin (TBT) tributyltin chloride (TrBT-Cl) triphenyltin chloride (TrPT-C1) and tetraphenyltin (TPT) respectively. A representative chromatogram is shown in Fig.9. The RSD for five 50 nl injections containing 0.5 ng of tin ranged from 1.3 to 3.4%. The potential for a simultaneous multi-element chromatogram was also demonstrated (see Fig. 10) for the separation of tet rap hen yl t in and tet raphen yllead. A comparison of a flame ionization detector (FID) and ICP-MS in the determination of organometallics separated by SFC has been presented by Vela and C a r u ~ o . ~ ~ Better resolution was obtained with SFC-FID and the differences were attributed to fluctuations in the temperature of the transfer line used to interface the SFC and ICP-MS instruments. Nevertheless a mixture of tri- and tetra- organotins was completely resolved using the SFC-ICP-MS system with a 4 m SB-biphenyl capillary column (50 pm i.d.and 375 pm 0.d.). Detection limits for TBT TrBT-C1 TrPT-C1 and TPT using SFC-FID were 10.3 12.5 12.0 and 9.0 pg respectively. These results indicate that lower detection limits are obtained with SFC-ICP-MS.I4 In addition to the advantages of high sensitivity and selectivity of plasma mass spectrometry as a detector for SFC ICP-MS does not give a solvent peak allowing the detection of organometallics that co-elute with the solvent and modifiers in the mobile phase. Determination of mercury- and lead-containing com- pounds by coupling SFC with ICP-MS has been presented by Carey et A comparison of single-ion monitoring detection limits and mass detection by time resolved analysis was presented for diethyl mercury and tri- and tetra-butyl lead compounds.Single-ion monitoring pro-794 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1993 VOL. 8 vided detection limits in the range 0.5-10 pg for these compounds using a 2.5 m SB-biphenyl capillary column and a carbon dioxide mobile phase. When analysing the total ion beam chromatogram obtained in a multi-mass detection mode detection limits were approximately 0.7-50 pg and the chromatograms obtained by extracting the signals at the masses of the analytes provided detection limits in the range 10-100 pg. Conclusions The coupling of different chromatographic methods such as LC and SFC with plasma mass spectrometry provides the sensitivity necessary to achieve analysis with selectivity and ultra-trace levels of detection. Detection levels from sub-ng to pg are possible while retaining valuable speciation information.The possibility of obtaining multi-element chromatograms with a single sample injection has been demonstrated. The authors are grateful to the National Institute of Envirionmental Health Sciences for partial support of this work through grant numbers ES03221 and ES04908. 1 2 3 4 5 6 7 8 9 10 References Brinckman F. E. and Bellama J. M. Organometals and Organometalloids. Occurrence and Fate in the Environment ACS Symposium Series 82 Washington DC 1978. Craig P. J. Organometallic Compounds in the Environment. Principles and Reactions Wiley New York 1986. Harrison R. M. and Rapsomanikis S. 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Spectrom. 1989 4 279. 25 Sheppard B. S. Shen W. L. Caruso J. A. Heitkemper D. T. and Fricke F. L. J. Anal. At. Spectrom. 1990 5 431. 26 Sheppard B. S. Caruso J. A. Heitkemper D. T. and Wolnik K. A. Analyst 1992 117 971. 27 Roehl R. and Alforque M. M. At. Spectrosc. 1990 11 210. 28 Kawabata K. Kishi Y. Kawaguchi O. Watanabe Y. and Inoue Y. Anal. Chem. 1991,63 2137. 29 Dean J. R. Munro S. Ebdon L. Crews H. M. and Massey R. C. J. Anal. At. Spectrom. 1987 2 607. 30 Mason A. Z. Storms S. D. and Jenkins K. D. Anal. Biochem. 1990 186 187. 31 Matz S. G. Elder R. C. and Tepperman K. J. Anal. At. Spectrom. 1989 4 767. 32 Crews H. M. Dean J. R. Ebdon L. and Massey R. C. Analyst 1989 114 895. 33 Vela N. P. Dissertation University of Cincinnati 1992. 34 Vela N. P. and Caruso J. A. J. Chromatogr. in the press. 35 Carey J. M. Vela N. P. and Caruso J. A J. Anal. At. Spectrom. 1992 7 1 173. Paper 3/00832K Received February 11 I993 Accepted March 19 I993

ISSN:0267-9477    

DOI:10.1039/JA9930800787

出版商:RSC    

年代:1993

数据来源: RSC