摘要:

Sixth Biennial National Atomic Spectroscopy Symposium will be held at Polytechnic South West Plymouth UK 22-24 July 1992 The symposium will provide a forum where interesting and useful applications of atomic spectros- copy can be reported and discussed. In addition to plenary invited and submitted lectures a particu- lar feature of the meeting will be the presentation of posters. There will also be an exhibition and a social programme for delegates and their guests. Scientific programme will include Plenary Lecturers- M.W. Blades (Vancouver BC Canada) B.V. L’vov (Leningrad USSR) J.W. McLaren (Ottawa Ontario Canada) K. Niemax (Dortmund Germany) B.L. Sharp (Loughborough UK) Invited Lecturers- J. S. Crighton (Sunbury-on-Thames UK) H. Falk (Kleve Germany) S.J. Hill (Plymouth UK) D.Littlejohn (Glasgow UK) C. McLeod (Shefleld UK) G. Schlemmer (Uberlingen Germany) P. Stockwell (Sevenoaks UK) J.F. Tyson (Amherst MA USA) J.G. Williams (Egham UK) A.M. Ure (Glasgow UK) This meeting is organized by the Atomic Spectroscopy Group Analytical Division of The Royal Society of Chemistry. Further information can be obtained from the Chairman of the organizing committee Dr S. J. Hill Department of Environmental Sciences Polytechnic South West Drake Circus Plymouth Devon PL4 8AA UKRamon M. Barnes Editor Department of Chemistry GRC Towers University of Massachusetts Amherst MA 01003-0035 Telephone (41 3) 545-2294 fax 545-4490 Objective The ICP lNFORMA TlON 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 during the past decade has become the leading spectrochemi- cal excitation source for atomic emission spectroscopy. ICP sources also are applied commercially as an ion source for mass spectrometry and as an atom and ion cell in atomic fluorescence 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 lNFORMA TlON NEWSLETTER in 1975. Other popular plasma sources i. e.microwave induced plasmas direct current plas- mas and glow discharges also are included in the scope of the ICP lNFORMA TlON NEWSLETTER. Scope As the only authoritative monthly journal of its type the ICP lNFORMA TlON 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 lNFORMATlON NEWSLETTER provides a concise and systematic source of information and background material needed for the selection of instrumentation or the development of methodology. For the experienced scientist it offers a sin- gle-source reference to current developments and literature. Editoriai The /CP /NFORMAT/ON 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 Spectrochemistry sponsored by the ICP INFORMATION NEWSLETTER. Regular Features Original submitted and invited research articles by ICP Complete bibliography of all major ICP publications. Abstracts of all ICP papers presented at major US and inter- First-hand accounts of world-wide ICP developments. Special reports on dcp microwave glow discharge and other Calendar and advanced programs of plasma meetings. Technical translations and reprints of critical foreign-lan- Critical reviews of plasma-related books and software.and plasma experts. national meetings. plasma progress. guage ICP papers. Conference Activities The ICP lNFORMATlON NEWSLETTER has sponsored six 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 Spectrochemical Analysis (Wiley) Plasma Spectrochemistry and Plasma Spectrochemistry I/-IV (Pergamon Press) as well as in special issues of Spectrochimica Acta Part 8 and Journal of Analytical Atomic Spectrometry. The 1992 Winter Confer- ence on Plasma Spectrochemistry will be held in San Diego California January 6 - 11 1992; its proceedings will be published by Fall 1992.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 17 runs from June 1991 through May 1 992. Back issues beginning with Volume 1 May 1975 also are available. To begin a subscription complete the form below and submit it 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. 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 Am herst MA 01 003-0035 USA. Start a subscription for the following issue tJ Volume(s)- (June 19- - May 19- ) or 17 19 (January - December). Enclosed 0 Prepayment 0 Check or money order CIVISA 0 Mastercard Account No. (All 13 or 16 digits) ,a Purchase order NO.^ or tJ Send invoice. Date Cardholder Name Expiration date Cardholder Signature .Amount Due $ Mail to Name Organization Address City State/Country ZI P/Postalcode Telephone Telex/fax Note For each credit-card transaction a 3% service charge will be added reflecting our bank charges. Current subscription rates are $60 (North America) $85 (Europe South America) or $94 (Africa Asia Indian/Pacific Ocean Areas Middle East and USSR). 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. Circle 004 for further information

ISSN:0267-9477    

DOI:10.1039/JA99106BP017

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

Journal of Analytical Atomic Spectrometry (Including Atomic Spectrometry Updates) JAAS Editorial Board* Chairman L. Ebdon (Plymouth UK) J Egan (Cambridge UK) D L Miles (Keyworth UK) D A Hickman (London UK? B L Sharp (Loughborough UK? J Marshall (Middlesbrough UK) R D Snook(Manchestei UK) J M Mermet (Vdleurbanne France) *The JAAS Editorial Board reports to the Analytical Editorial Board Chairman A G Fogg (Loughborough UK) JAAS Advisory Board F C Adams (Antwerp Belgium) R M Barnes (Amherst MA USA) G M Hieftje (Bloomington IN USA) L Bezur (Budapest Hungary) R F Browner (Atlanta GA USA) S Caroli (Rome Italy) A J Curtius (Rio de Janeiro Brazil) L de Galan (Vlaardmgen The Netherlands) J B Dawson (Leeds UK) R E Sturgeon (Ottawa Canada) K Dittrich (Leipng Germany) W Frech (UmeS Sweden) A Walsh K B (Victoria Australia) K Fuwa (Tokyo Japan) B Welz (Uberlingen FRG) A L Gray (Egham UM T S West (Aberdeen UM S Greenfield (Loughborcugh UK) G Horlick (Edmonton Canada) B V L'vov (Leningrad USSR) Ni Zhe-ming (Beiling China) N Omenetto (lspra Italy) T C Rains (Charleston SC USA) R Van Grieken (Antwerp Belgium) Atomic Spectrometry Updates Editorial Board Chairman *D L J Armstrong (Dumfnes UM J R Bacon (Aberdeen UK? C Barnard (Glasgow UK) R M Barnes (Amherst MA USA) S Branch (High Wycombe UK) R Bye (Oslo Norway) J Carroll (Middlesbrough UK) M R Cave (Keyworth UK) "J M Cook (Keyworth UK) "M S Cresser (Aberdeen UK) H M Crews (Norwich UK) J S Crighton (Sunbury-on-Thames UK) J R Dean (Newcastle upon Tyne UK) "J B Dawson (Leeds UKI " L Ebdon (Plymouth UK) *J Egan (Cambridge UK) "A T Ellis (Oxford UK) *D J Halls (Glasgow UK) "D A Hickman (London UK) * S J Hill (Plymouth UK) J Fazakas (Bucharest Romania) K W Jackson (Albany NY USA) R Jowitt (Middlesbrough UK) K Kitagawa (Nagoya Japan) J Kubova (Bratislava Czechoslovakia) "D Littlejohn (Glasgow UK) Miles (Keyworth UK) "J Marshall (Middlesbrough UK) H Matusiewicz (Poznan Poland) J M Mermet (Villeurbanne France) R G Michel (Storrs CT USA) T Nakahara (Osaka Japan) Ni Zhe-ming (Beying China) P R Poole (Hamilton New Zealand W J Price (Ashburton UK) C J Rademeyer (Pretoria South Afr/ca) M H Ramsey(London UK) A Sanz-Medel (Ovredo Spain) I L Shuttler (Uberlmgen FRG) S T SparKes (Plymouth UK) R Stephens (Halifax Cmada) J Stupar (Llubhana Yugoslavia) R E Sturgeon (Ottawa Canada) A Taylor (Guildford UKi A P Thorne (London LIM G C Turk (Gaithersburg MD USA) J F Tyson (Amherst MA USA) *A M Ure (Aberdeen UK) S J Walton (Crawley OK) P Watkins (London Uk) B Welz (Uberlingen FF'G) J Williams (Egham UKi J B Willis (Victorm Au.;tralia) *Members of the ASU Executive Committee ~ ~ ~ ~~ ~ Editor JAAS Judith Egan The Royal Society of Chemistry Dr J M Harnly Thomas Graham House Science Park Milton Road Cambridge CB4 4WF UK Telex No 81 8293 Fax 0223 423623 Assistant Editors Brenda Holliday Editorial Secretary Monique Warner US Associate Editor JAAS US Department of Agriculture Beltsville Human Nutriton Research Center Beltsville MD 20705 USA Telephone 30 1 -344-2 569 Telephone 0223 420066 BLDG 161 BARC-EAST Paula O'Riordan Sheryl Whitewood Advertisements Advertisement Department The Royal Society of Chemistry Burlington House Piccadilly London W I V OBN UK.Telephone 071-437 8656. Fax 071-437 8883 Information for Authors Full details of how to submit materials for publica- tion in JAAS are given in the Instructions to Authors in Issue 1 Separate copies are available on request The Journal of Analytical Atomic Spectrometry (JAA.9 is an international journal for the publica- tion of original research papers communications and letters concerned with the development and analytical application of atomic spectrometric techniques The journal is published eight times a year including comprehensive reviews of specific topics of interest to practising atomic spectrosco- pists and incorporates the literature reviews which were previously published in Annual Reports on Analytical Atomic Spectroscopy (ARAAS) Manuscripts intended for publication must de- scribe original work related to atomic spectromet- ric analysis Papers on all aspects of the subject will be accepted including fundamental studies novel instrument developments and practical ana- lytical applications As well as AAS AES and AFS papers will be welcomed on atomic mass spectro- metry and X-ray fluorescence/emission spectro- metry Papers describing the measurement of molecular species where these relate to the char- acterization of sources normally used for the pro- duction of atoms or are concerned for example with indirect methods of analysis will also be ac- ceptable for publication Papers describing the de- velopment and applications of hybrid techniques ( e g GC-coupled AAS and HPLC-ICP) will be par- ticularly welcome Manuscripts on other subjects of direct interest to atomic spectroscopists in- cluding sample preparation and dissolution and analyte pre-concentration procedures as well as the statistical interpretation and use of atomic spectrometric data will also be acceptable for pub- lication There is no page charge The following types of papers will be consid- ered Full papers describing original work Comrnunicatmx which must be on an urgent matter and be of obvious scientific importance Communications receive priority and are usually published within 2-3 months of receipt They are intended for brief descriptions of work that has progressed to a stage a t which it is likely to be valuable to workers faced with similar problems Reviews which must be a critical evaluation of the existing state of knowledge on a particular facet of analytical atomic spectrometry Every paper (except Communications) will be submitted to at least two referees by whose advice the Editorial Board of JAAS will be guided as to its acceptance or rejection Papers that are accepted must not be published elsewhere except by permission Submission of a mancr- script will be regarded as an undertaking that the same material is not being considered for publica- tion by another journal Manuscripts (three copies typed in double spacing) should be sent to Judith Egan Editor.JAAS or Dr J M Harnly US Associate Editor JAAS All queries relating to the presentation and sub- mission of papers and any correspondence re- garding accepted papers and proofs should be directed to the Editor or US Editor (addresses as above) Members of the JAAS Editorial Board (who may be contacted directly or via the Editorial Office) would welcome comments suggestions and advice on general policy matters concerning JAAS ~ ~ Fifty reprints are supplied free of charge.Journal of Analytical Atomic Spectrometry (JAAS) (ISSN 0267-9477) is published eight times a year by The Royal Society of Chemistry Thomas Graham House Science Park Milton Road Cambridge CB4 4WF UK. All orders accompanied with payment should be sent directly to The Royal Society of Chemistry Turpin Tractions Ltd. Blackhorse Road Letchworth Herts. SG6 1 HN UK Tel. +44 (0) 462 672555; Telex 825372 Turpin G; Fax +44 (0) 462 480947.Turpin Transactions Ltd. is wholly owned by The Royal Society of Chemistry. 1991 Annual subscription rate EC €309.00 USA $728.00 Rest of World €355.00. Customers should make payments by cheque in sterling payable on a UK clearing bank or in US dollars payable on a US clearing bank. Air freight and mailing in the USA by Publications Expediting Inc. 200 Meacham Avenue Elmont NY 11003. USA Postmaster send address changes to Journal of Analytical Atomic Spectrometry (JAASI Publications Expediting Inc. 200 Meacham Avenue Elmont NY 11 003. Second class postage paid at Jamaica NY 11431. All other despatches outside the UK by Bulk Airmail within Europe Accelera?ed Surface Post outside Europe. PRINTED IN THE UK. 0 The Royal Society of Chemistry 1991.All rights reserved. No part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photographic recording or otherwise without the prior permission of the publishers.Journal of Analytical Atomic Spectrometry (Including Atomic Spectrometry Updates) JAAS Editorial Board* Chairman B. L. Sharp (Loughborough UK) J. Egan (Cambridge UK) D. A. Hickman (London UK) J. Marshall (Middlesbrough UK) J. M. Mermet (Villeurbanne France) D. L. Miles (Keyworth UK) R. D. Snook (Manchester UK) *The JAAS Editorial Board reports to the Analytical Editorial Board Chairman A. G. Fogg (Loughborough UK) JAAS Advisory Board F. C. Adams (Antwerp Belgium) R. M. Barnes (Amherst MA USA) L.Bezur (Budapest Hungary) R. F. Browner (Arlanta GA USA) S . Caroli (Rome Italy) A. J. Curtius (Rio de Janeiro Brazil) L. de Galan (Vlaardingen The Netherlands) J. B. Dawson (Leeds UK) K. Dittrich (Leipzig Germany) W . Frech (UmeB Sweden) K. Fuwa (Tokyo Japan) A. L. Gray (Egham UK) S. Greenfield (Loughborough UK) G. M. Hieftje (BlUOmingtOn IN USA) G. Horlick (Edmonton Canada) B. V. L'vov (Leningrad USSR) Ni Zhe-ming (Beijing China) N. Omenetto (lspra Italy) T. C . Rains (Charleston SC USA) R. E. Sturgeon (Ottawa Canada) R . Van Grieken (Antwerp Belgium) A. Walsh,,K. B. (Victoria Australia) B. Welz (Uberlingen FRG) T. S. West (Aberdeen UK) Atomic Spectrometry Updates Editorial Board Chairman "D L J Armstrong (Dumfries UK) J R Bacon (Aberdeen UK) C Barnard (Glasgow UK) R M Barnes (Amherst MA USA) S Branch (High Wycombe UK) R Bye (Oslo Norway) J Carroll (Middlesbrough UK) M R Cave (Keyworth UK) "J M Cook (Keyworth UK) "M S Cresser (Aberdeen UK) H M Crews(Norwich UK) J S Crighton (Sunbury-on-Thames UK) J R Dean (Newcastle upon Tyne UK) "J B Dawson (Leeds UK) "J Egan (Cambridge UK) "A T Ellis (Oxford UK) J Fazakas (Bucharest Romania) D J Halls (Glasgow UK) "D A Hickman (London UK) "S J Hill (Plymouth UK) K W Jackson (Albany NY USA) R Jowitt (Middlesbrough UK) K Kitagawa (Nagoya Japan) J Kubova (Bratislava Czechoslovakia) "D Littlejohn (Glasgow UK) "J Marshall (Middlesbrough UK) Miles (Keyworth UK) H.Matusiewicz (Poznan Poland) J. M. Mermet (Wlleurbanne France) R. G. Michel (Storrs CT USA) T. Nakahara (Osaka Japan) Ni Zhe-ming (Beijing China) P.R. Poole (Hamilton New Zealand W. J. Price (Ashburton UK) C. J. Rademeyer (Pretoria South Africa) M . H. Ramsey (London UK) A. Sanz-Medel (Oviedo Spain) "B. L. Sharp (Loughborough UK) I. L. Shuttler (Uberlingen FRG) S. T. Sparkes (Plymouth UK) R. Stephens (Halifax Canada) J. Stupar (Ljubljana Yugoslavia) R . E. Sturgeon (Ottawa Canada) A. P. Thorne (London UK) G. C. Turk (Gaithersburg MD USA) J. F. Tyson (Amherst MA USA) "A. M. Ure (Aberdeen UK) S. J. Walton (Crawley UK) P. Watkins (London UK) B. Welz (Uberlingen FRG) J. Williams (fgham UK) J. B. Willis (Victoria Australia) "A. Taylor (Guildford UK) "Members of the ASU Executive Committee Editor JAAS Judith Egan The Royal Society of Chemistry Thomas Graham House Science Park Milton Road Cambridge CB4 4WF UK Telex No 81 8293 Fax 0223 423623 Assistant Editors Brenda Holliday €ditorial Secretary Monique Warner US Associate Editor JAAS Dr J.M Harnly US Department of Agriculture Beltsville Human Nutriton Research Center Beltsville MD 20705 USA Telephone 301 -344-2569 Telephone 0223 420066 BLDG 161 BARC-EAST Paula O'Riordan Sheryl Whitewood Advertisements Advertisement Department The Royal Society of Chemistry Burlington House Piccadilly London WIV OBN UK Telephone 071-437 8656. Fax 071-437 8883 Information for Authors Full details of how to submit materials for publica- tion in JAAS are given in the Instructions to Authors in Issue 1 Separate copies are available on request The Journal of Analytical Atomic Spectrometry (JAAS) is an international journal for the publica- tion of original research papers communications and letters concerned with the development and analytical application of atomic spectrometric techniques The journal is published eight times a year including comprehensive reviews of specific topics of interest to practising atomic spectrosco- pists and incorporates the literature reviews which were previously published in Annual Reports on Analytical Atomic Spectroscopy (ARAAS) Manuscripts intended for publication must de- scribe original work related to atomic spectromet- ric analysis Papers on all aspects of the subject will be accepted including fundamental studies novel instrument developments and practical ana- lytical applications As well as AAS AES and AFS papers will be welcomed on atomic mass spectro- metry and X-ray fluorescence/emission spectro- metry Papers describing the measurement of molecular species where these relate to the char- acterization of sources normally used for the pro- duction of atoms or are concerned for example with indirect methods of analysis will also be ac- ceptable for publication Papers describing the de- velopment and applications of hybrid techniques (e g GC-coupled AAS and HPLC-ICP) w\\\ be par- ticularly welcome Manuscripts on other subjects of direct interest to atomic spectroscopists in- cluding sample preparation and dissolution and analyte pre-concentration procedures as well as the statistical interpretation and use of atomic spectrometric data will also be acceptable for pub- lication There is no page charge The following types of papers will be consid- ered full papers describing original work Communications which must be on an urgent matter and be of obvious scientific importance Communications receive priority and are usually published within 2-3 months of receipt They are intended for brief descriptions of work that has progressed to a stage at which it is likely to be valuable to workers faced with similar problems Reviews which must be a critical evaluation of the existing state of knowledge on a particular facet of analytical atomic spectrometry Every paper (except Communications) will be submitted to at least two referees by whose advice the Editorial Board of JAAS will be guided as to its acceptance or rejection Papers that are accepted must not be published elsewhere except by permission Submission of a manu- script will be regarded as an undertaking that the same material is not being considered for publica- tion by another journal Manuscripts (three copies typed in double spacing) should be sent to Judith Egan Editor JAAS or Dr J M Harnly US Associate Editor JAAS All queries relating to the presentation and sub- mission of papers and any correspondence re- garding accepted papers and proofs should be directed to the Editor or US Editor (addresses as above) Members of the JAAS Editorial Board (who may be contacted directly or via the Editorial Office) would welcome comments suggestions and advice on general policy matters concerning JAA S Fifty reprints are supplied free of charge Journal of Analytical Atomic Spectrometry (JAAS) (ISSN 0267-9477) is published eight times a year by The Royal Society of Chemistry Thomas Graham House Science Park Milton Road Cambridge CB4 4WF UK All orders accompanied with payment should be sent directly to The Royal Society of Chemistry Turpin Tractions Ltd Blackhorse Road Letchworth Herts SG6 1 HN UK Tel +44 (0) 462 672555 Telex 825372 Turpin G Fax +44 (0) 462 480947 Turpin Transactions Ltd is wholly owned by Thd Royal Society of Chemistry 1991 Annual subscription rate EC f309 00 USA $728 00 Rest of World €355 00 Customers should make payments by cheque in sterling payable on a UK clearing bank or in US dollars payable on a US clearing bank Air freight and mailing in the USA by Publications Expediting Inc 200 Meacham Avenue Elmont NY 11003 USA Postmaster send address changes to Journal of Analyrical Atomic Spectrometry (JAAS) Publications Expediting Inc 200 Meacham Avenue Elmont NY 11 003 Second class postage paid a t Jamaica NY 11431 All other despatches outside the UK by Bulk Airmail within Europe Accelerated Surface Post outside Europe PRINTED IN THE UK 0 The Royal Society of Chemistry 1991 All rights reserved No part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photographic recording or otherwise without the prior permission of the publishers

ISSN:0267-9477    

DOI:10.1039/JA99106FX021

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

JASPEZ 6(6) 405-498 September 199 1 Journal of Analytical Atomic Spectrometry CONTENTS ~ ~~ NEWS AND VIEWS 405 Royal Society of Chemistry's Sesquicentenary-Sheryl Whitewood 406 Conference Reports-G Samuel Hurst Ian L Shuttler Barry L Sharp 41 7 Conferences and Meetings 418 Courses 420 Journal Style Update-Alan McNaught 420 Papers in Future Issues PAPERS 421 431 439 445 451 457 465 473 477 483 487 493 497 Comparison of Normal and Low-flow Torches for Inductively Coupled Plasma Mass Spectrometry Using Optimized Operating Conditions-E Hywel Evans Les Ebdon Analytical Performance Evaluation of a 40.68 MHz Inductively Coupled Plasma Mass Spectrometer-Chang J Park Kwang W Lee Verification of a Correction Procedure for Measurement of Lead Isotope Ratios by Inductively Coupled Plasma Mass Spectrometry-Michael E Ketterer Michael J Peters Preston J Tisdale Quantitative Analysis of Trace Elements in Carbonates Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry-William T Perkins Ronald Fuge Nicholas J G Pearce Comparison of Refractive Index Energy Dispersive X-ray Fluorescence and Inductively Coupled Plasma Atomic Emission Spectrometry for Forensic Characterization of Sheet Glass Fragments-Robert D Koons Charles A Peters Pamela S Rebbert Rapid Stopped-flow Microwave Digestion System-Vassili Karanassios F H Li B Liu Eric D Salin Investigations on the Determination of Chloride and Bromide by Furnace Atomic Non-thermal Excitation Spectrometry and Furnace Ionic Non-thermal Excitation Spectrometry-Klaus Dittrich Bernard Radzuik Bernhard Welz Determination of Lead in Soil by Slurry-Electrothermal Atomic Absorption Spectrometry With a Fast Temperature Programme-Michael W Hinds Kathryn E Latimer Kenneth W Jackson Platform in Furnace Zeeman-effect Atomic Absorption Spectrometric Determination of Arsenic in Beer by Atomization of Slurries of Sample Ash -Maria Luisa Cervera As<censio Navarro Rosa Montoro Miguel de la Guardia Amparo Salvador Dermination of Lead by HMride Generation Atomic Absorption Spectrometry With In Situ Concentration in a Zirconium Coated Graphite Tube-Yan Xiu-ping Ni Zhe-ming Behaviour of Various Organic Solvents and Analytes in Electrothermal Atomic Absorption Spectrometry-Emil Tserovsky Sonia Arpadjan Inserted Injector Tubes for Inductively Coupled Plasma Spectrometry-Lyne S Gervais Eric D Salin CUMULATIVE AUTHOR INDEX INTER-LABORATORY NOTE Typeset by Burgess & Son (Abmgdon) Ltd __ PAGF HROS Printed in Great Britain by Page Bros Norwicht STANDARD TYPE S.&. J. JUNIPER 8t Co. 7 Potter Street Harlow Essex. Tel 0279 422456 PERKIN-ELMER TYPE Fax 0279 438095 Telex 817907 JUNHAR G Circle 001 for further information ROYAL SOCIETY OF CHEMISTRY The COSHH Regulations A Practical Guide Edited by D. Simpson and W. G. Simpson Principal Consultants Analysis for Industry The COSHH (Control of Substances Hazardous to Health) Regulations are the most significant health and safety legislation since the Health and Safety at Work Act 1974. Chemists are one of the largest professional groups to be affected by these regulations and this new book provides a definitive guide to their implications and implementation.The Regulations apply to employers in every walk of life as well as to the self-employed and The COSHH Regulations A Practical Guide warns of the penalties that will follow any harm to employees or the general public. It offers realistic help and advice on the steps to be taken to comply with the Regulations or prepare a defence if necessary. Based on the editors’ and contributors’ wide experience the book is immensely practical and provides examples of the application of the Regulations in many different fields of business and commercial life. It is one of the few independent publications available on the COSHH Regulations‘and is an essential addition to the bookshelf of anyone with an interest in or responsibility for safety. Hardcover Approx 208 pages 234 x 156 mm Price f45.00 ISBN 0 85186 189 X Autumn 1991 ROYAL SOCIETY OF To Order Please write to the Royal Society of Chemistry Turpin Transactions Ltd Blackhorse Road Letchworth Herts SG6 1 HN UK. or telephone (0462) 672555 quoting your credit card details. We can now accept Access/Visa/MasterCard/Eurocard Turpin Transactions Ltd distributors is wholly owned by the Royal Society of Chemistry. For information on other books and journals please write to Royal Society of Chemistry Sales and Promotion Department Thomas Graham House Science Park Milton Road Cambridge CB4 4WF UK. RSC Members should obtain members prices and order from The Membership Affairs Department at the Cambridge address above. information Services Circle 002 for further information

ISSN:0267-9477    

DOI:10.1039/JA99106BX023

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

405 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 The Royal Society of Chemistry’s Sesquicentenary 1991 Pro Scientia et Humanitate On February 23rd 1841 a meeting called by Robert Warington resolved that ‘it is expedient that a chemical society be formed’. On March 30th of that year the founding meeting of the Chemical Society of London was held at the Royal Society of Arts; Thomas Graham was elected as the first Presi- dent and R. Warington as an Hono- rary Secretary. The first Honorary and Foreign Member was Justus von Liebig. In 1874 the Society of Public Ana- lysts was founded which in 1907 became the Society of Public Analysts and other Analytical Chemists and was later to become the Society for Analytical Chemistry (SAC). The SAC in 1968 had a total of 2268 members of which 19 18 were based in the UK it also produced the journals The Ana- lyst Analytical Abstracts and Proceed- ings of the Societv for Analytical Chemistry.In 1877 The Institute of Chemistry was founded which in 1944 became the Royal Institute of Chemistry (RIC) by Royal Charter. In 1967 the first amalgamation dis- cussions began between the various organizations. In 1972 the Chemical Society the RIC and the Faraday Society amalgamated. There was also a provisional agreement with the SAC. However at this point it was 98 years old and it was decided that full amal- gamation should wait until the end of 1974 after the centenary celebrations at which it was announced that the SAC had ‘scored 100 not out innings declared closed’. The amalgamation was complete.On June lst 1980 there was com- plete unification of all of the societies under the one name The Royal Society of Chemistry. So from the founding 77 members of the Chemical Society of London the Society has grown over the past I50 years to a current member- ship of over 43000 world-wide with over 300 permanent staff based at premises in Burlington House Lon- don (front cover) Thomas Graham House Cambridge (named after the first President) and Distribution Centre Letchworth. The RSC is actively celebrating the sesquicentenary of the founding of the Chemical Society. An extensive agenda of celebratory activities and events have been taking place through- out the year probably the most notable being the Annual Congress in April at Imperial College London.Attended by over 2000 chemists the opening ceremony took place in the Great Hall where the guest of honour Lord Porter expressed the sentiment ‘the debt mankind owes to chemistry is enormous’. The Science Museum also mounted an exhibition in Imperial College on the foundation of the Chemical Society. Other events with a historical theme were organized and included the ple- nary address by Professor Colin Rus- sell (Chemical bonds 184 1-1 99 l) the Historical Group’s symposium (His- torical highlights of the 150 years) and a reception at the Royal Institution. The reception included an address by the Director Professor Sir John Tho- mas on ‘The Genius of Faraday’ as this year also marks the bicentenary of Michael Faraday’s birth. At this year’s Congress there was a strong industrial and practical repre- sentation among the symposium top- ics which went some way to alleviat- ing its undeserved although tra- ditional image of being ‘dry and aca- demic’.The Industrial Division held a joint symposium with the Royal Neth- erlands Chemical Society which at- tracted industrial sponsorship. The meeting was the fourth in a series of international conferences and avoided a clash of interests. Another area of new science being considered was the area of sensor technology. The Analytical Division ran a series of sessions on ‘Lumines- cence and optical sensors’ and its Electroanalytical Group combined with the Faraday Division’s Electro- chemistry Group to set up a sympo- sium on new electrochemical sensors. The special nature of this year’s congress brought out a high proportion of distinguished speakers including El- ias Corey Sir Derek Barton and Jean- Marie Lehn all Nobel Laureates.Other symposia topics could be broadly labelled professional matters such as the environment education in the future and women in chemistry which was attended by Dorothy Hodgkin the most distinguished British female chemist whose Nobel prizewinning research in crystal- lography was discussed. The biennial meeting of the interna- tional chemical society Presidents took place at Burlington House an event normally held in conjunction with the IUPAC congress but arranged this year to honour the RSC’s anniver- sary. There was also the second Chemistry and Developing Countries Symposium run by the RSC and sup- ported by the British Council and the Commonwealth Science Council.Other events planned have been the Anniversary Concert performed by the Royal College of Music and the fash- ion show ‘Chemically Chic!’ which took place at London’s Savoy Hotel. ‘Chemically Chic!’ generated the most media coverage that the RSC has ever received for a single event. The show aimed to stress how chemistry has influenced fashion in ways both obvious and subtle obvious through dyes and synthetic materials; subtle through the treatment or processing of ‘natural’ fibres so that wool cotton and silk are comfortable to wear and easy to care for. The highlight of the show however was the new Licritherm ther- mochromic textile ink (a development by Merck) and its use in the fabric industry.The ink is based upon ther- mochromic liquid crystals which are incorporated into microcapsules. The crystals give rise to changes in the waveband of the reflected light. They are screen printed onto fabrics by using an aqueous binder resin. When the fabric changes temperature with atmospheric conditions or where the fabric is in contact with the human body the colour changes from colour- less to red and then through the colours of the visible spectrum to blue violet and finally to colourless again as the temperature increases. The chang- ing colours are viewed against a dark background for the greatest effect. In Cambridge an Anniversary Open Day was held at Thomas Graham House on June 26th 199 1. The theme of the day reflected 150 years of scientific publishing.Thomas Graham House (TGH) is the information man- agement and membership base for the RSC and is to be found on Cam- bridge’s renowned Science Park. Opened in 1989 by HRH Prince Phi- lip it houses the editorial offices of all of the primary journals including JAAS. The TGH open day was attended by about 400 top chemists and scientists from industry and the academic world a variety of other people including406 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 some local Members of Parliament were also invited. The staff of TGH spent the day showing the visitors around the building and explaining the process of scientific publishing. Some historical pieces of printing equipment and original journals were on display to help with the explana- tions.Lunch was in the form of a Victorian buffet with the catering staff dressed appropriately. Some other members of staff also entered into the spirit of the day and dressed in full Victorian costume at the end of the day they must have been extremely glad to divest themselves of the heavy and cumbersome garments. During the afternoon the guests were invited to attend a TGH version of the extremely successful London fashion show but with a difference! Gone were the TV presenters and professional models and in their place a few willing and able members of staff including one rather unwilling partici- pant the Editor of JAAS Judith! At this point thanks are due to Pat Styris wife of Dr. Dave Styris (Pacific Northwest Laboratories WA USA) without whose help the TGH fashion show would definitely not have been the same. She was seconded as ward- robe assistant and managed to make sure that all of the models looked great and after a few stitches here and there made all of the dresses fit-hard work but genuinely appreciated. Dr. Dave Styris and Dr. Barry Sharp (Loughborough University) attended the show and comimented that it was great fun and all of the models were excellent. However it would appear that it was a good thing that the Licritherm costumes were restricted to the models and not the audience whose temperatures were definitely rising. The day finished with a ‘staff only’ evening (we deserved it-honest!) which included a disco and a great deal of food and drink. The next day was a little quiet in some offices but of course the Analytical staff were their usual efficient selves not a bleary eye in sight. Let’s hope the RSC’s next 150 years go as well. Sheryl Whitewood Assist ant Editor JAAS

ISSN:0267-9477    

DOI:10.1039/JA9910600405

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

406 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 Conference Reports Fifth International Symposium on Resonance Ionization Spectroscopy and Its Applications (RIS-90) September 16th-21 st 1990 Varese Italy If scope challenge diversity of appli- cations and creativity are valid indi- cators Resonance Ionization Spec- troscopy (RIS) has come of age. These qualities and more were conspicuous during RIS-90. The inherent features of RIS in which tuned lasers are used to ionize atoms and molecules lead to analytical measurement systems which are far ahead of most conven- tional methods in both selectivity and sensitivity. It is the combination of these two qualities that is being em- ployed by scientists around the world to tackle a diversity of challenging problems which were reported at Var- ese by over 100 scientists representing 22 countries.At RIS-90 there was participation from USSR (Moscow and Leningrad) Finland Germany France Italy China Scotland Wales England Bel- gium United States Switzerland Canada and others. The involvement of the Institute of Spectroscopy (Tro- itsk) which George Bekov from the USSR Academy of Sciences initiated at RIS-88 grew considerably at the last meeting. Besides Bekov other mem- bers of the combined advisory and programme committees included J. E. Parks N. Omenetto E. Arimondo P. Benetti P. Camus G. Goldstein H. J. Kluge P. Knight Y . Y . Kuzyakov B. Lehmann A. L'Huillier T. Lucatorto C. M. Miller K. Niemax G. Rossi H. Rubinsztein-Dunlop J. C. Travis and T. J. Whitaker. The host organization for RIS-90 was the Commission of the European Communities Joint Research Centre Ispra Site Italy under the leadership of Professor N.Onienetto who served as Co-chairman of the symposium. Working closely with Professor Omen- etto was Co-chairman James E. Parks director of the Institute of Resonance Ionization Spectroscopy of the University of Tennessee (USA). The five-day meeting was packed with technical sessions in which 61 papers were delivered orally at 14 technical sessions and an additional 56 technical presentations were made at poster sessions. In addition 'A Short Course on Resonance Ionization Spec- troscopy' was conducted for an esti- mated 66 participants who were both beginners and seasoned experts of RIS. And there were special events perhaps the most significant of these was the judging and presentation of two awards which were inaugurated this year.One of these was given to the best work performed by a graduate student and another was given to the best work presented in a poster. As the quality of all of the technical papers (plenary and invited lectures oral and poster presentations) was notably high it is with some trepida- tion that any are singled out for discus- sion. The examples chosen represent the range and the flavour of the meet- ing with the trust that those not mentioned will not feel slighted. A strong theoretical component con- tinues to be a vital part of these Symposia on RIS. From the beginning of the RIS work at Oak Ridge National Laboratory Marvin G. Payne has made valuable contributions which were important in their own right and were critical for the innovation and conduct of new experimental demon- strations of the power of RIS.His contribution at RIS-90 dealt with co- operative effects which are sometimes pressure dependent during three-pho- ton excitation of atomic levels. There is good agreement between the theory and the experiments which shows that destructive interferences can greatly reduce the excitation probability in certain circumstances. Although these effects are rarely evident in RIS appli- cations it is a reminder that subtleties continue to emerge. About three years ago it was ob- served that there can be hyperfine structure effects in resonance ioniza- tion even with broad-band laser radia- tion. This problem attracted the atten- tion of another theorist P.Lambro- poulos of the University of Southern California and the University of Crete. With a laser that overlaps the hyper- fine manifolds the key parameters areJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY. SEPTEMBER 199 1 VOL. 6 407 Rabi frequency ionization rates hy- perfine splitting pulse duration and bandwidth. Detailed calculations were presented by Professor Lambropoulos and comparisons were made with ex- perimental data. Another subtlety in photoionization was discussed by Professor V. N. Os- trovsky of Leningrad State University who dealt with the problem of photo- detachment of electrons when negative ions are placed in an electric field. Oscillatory structure in the photode- tachment cross-section as a function of energy were explicable in terms of a model which involves the idea that when alternative paths connect arbi- trary points in space interferences are observed.This effect is reminiscent of Young's double slit experiment which shows wavelike interferences with either photons or electrons even when these are so low in intensity that as particles they would pass through the slit one at a time. Workers experimenting with vari- ous forms of ionization have always had to worry about collective pheno- mena or space charge effects which can make it very difficult to collect and measure the total ionization produced. During the past two meetings RIS-88 and RIS-90 Professor F. Giammanco University of Pisa Italy has been tackling these difficult problems for laser ionization in matter.He is now able to give quantitative descriptions that agree with laser ionization experi- ments and the theory is being ex- tended to the ejection of high energy electrons owing to the interaction of intense laser beams with surfaces. New Laser Sources and RIS Applications As all forms of laser spectroscopy including RIS depend on the avail- ability of suitable laser sources the programme committees for nearly all of the RIS symposia have invited speakers who could keep us up-to-date on leading edged developments on laser sources. This year R. Wallen- stein University Kaiserslautern Ger- many lectured on the generation of intense laser light from the extreme ultraviolet to the infrared. Professor Wallenstein discussed the use of Nd:YAG harmonics for optical par- ametric oscillation (OPO) in barium borate and lithium borate for the generation of coherent radiation which is continuously tunable in the range of 300-3000 nm.Frequency doubling and mixing in these all-solid- state lasers give wavelengths as short as 160 nm. Higher order frequency mixing with krypton and argon can even give wavelengths as short as 58 nm (20 eV). Another significant trend in solid- state lasers is the development and use of diode lasers as sources and as pumps for other lasers. K. Niemax who chaired the session on laser sources has made impressive contribu- tions in this area. J. P. Young of the Oak Ridge National Laboratory re- ported on the use of diode lasers for isoiopically selective RIS of lan- thanum. However not all of the novel RIS work is carried out using solid- state lasers.Novel work is also carried out on isotopic selectivity using CW- dye lasers for instance B. A. Bushaw Pacific Northwest Laboratory re- ported on the use of these methods for isotopes such as *loPo in context with the Radon problem. Copper-vapour laser technology has matured and has unique applications because of the high repetition rates as was reported by C. E. Webb Oxford Lasers. B. L. Fearey Los Alamos National Laboratory USA and his colleagues S. C. Johnson and C. M. Miller have been working on methods to make RIS methods more sensitive and reliable by using CW lasers. Their approach is to develop an external cavity which promises to increase the circulating laser power by about a factor of 100 and thereby to increase ionization efficiencies to the tens of per cent level.A new concept in the use of CW lasers for excitation and strong elec- tric fields for the final ionization step in RIS schemes was introduced by R. Hergenroder and K. Niemax Institut fur Spectrochemie und angewandte Spektroskopie Dortmund Germany. The novelty is in the spatial separation of the excitation and ionization re- gions. When these processes occur in the same region the strong electric fields cause Stark shifts and splitting of the high Rydberg states required for field ionization. This in turn causes a loss of selectivity in resolving one isotope from another. It was shown that lithium atoms when excited to n>30 would live long enough so that the atom could enter the ionization compartment before decay.Mechanisms Basic Experiments and RIS Data Service P. Agostini CEN Saclay France re- ported some intriguing new results on the multiphoton ionization of atoms in intense laser fields. When the photo- electron spectra are taken with ultra- short laser pulses at a fixed wave- length they show a complex structure which can be related to Stark-induced resonances. Analysis of these spectra reveal the energies of atomic levels directly under intense laser irradia- tion. The key point is the use of the ultrashort laser pulses as the features of the energy levels wash out with the use of longer laser pulses. Basic experiments on excitation mechanisms in laser enhanced ioniza- tion (LEI) in flames were reported by Ove Axner Chalmers University of Technology Goteborg Sweden.Line shapes for two-step ionization and other experimental features could not be treated with a rate equation theory yet the density-matrix formulation does give satisfactory agreement. In other work on LEI N. Omenetto and his colleagues at the Environment In- stitute of the JRC Ispra have been able to record directly the Raman spectra of molecules while using atomic con- stituents of flames as novel photon detectors. The basic principles of the ionization of atoms in hot cavities have been investigated by V. I. Mishin at the Institute of Spectroscopy in Troitsk USSR. Particular attention was given to ion extraction permitting efficient detection of the lanthanide atoms in such cavities. The National Institute of Standards and Technology (NIST) of the United States has established a data service on RIS. Building on a long tradition (as the National Bureau of Standards) in Atomic Physics Data the NIST pro- gramme offers RIS data sheets on individual elements. Judging from the presentation by E.B. Saloman and the response generated from the devel- opers and users of RIS it appears that the new service is destined to have a bright future. RIS Applications to the Study of Rare Atoms One of the highlights of RIS-90 was a report on the applications to the study of rare atoms. As Professor H. J. Kluge Institut fur Physik Universitat Mainz Germany stated in his plenary paper much of our knowledge on the atomic nucleus has come from optical studies. Quantities such as nuclear spin magnetic dipole moment and spectroscopic quadrupole moment have been determined from optical spectroscopy as the hyperfine struc- ture is revealing these and other nu- clear parameters.On-line mass separa- tors equipped with techniques of laser spectroscopy for the determination of hyperfine structure in long chains of short-lived isotopes has made it pos- sible to catalogue the ground-state properties of some 30 elements involv- ing about 500 nuclear ground and isomeric states. The group of Professor Letokhov at Troitsk has collaborated with Profes- sor Kluge and his colleagues at Mainz in pioneering the use of RIS in many of these studies. Closely related work is being carried out by Professor A. E.408 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL.6 Barzakh Leningrad Nuclear Physics Institute USSR. A great deal of RIS work is also carried out at ISOLDE/ CERN ISOCELE/Orsay and Gatchina/ Leningrad. Professor J. E. Crawford and his colleagues at McGill Univer- sity are collaborating with groups at Orsay to study the nuclear properties of gold and platinum isotopes. Detec- tion of very rare isotopes in which RIS is applied to collinear techniques was reported by Yu. A. Kudryavstsev at Troitsk. This powerful technique for obtaining high isotopic resolution is based on the production of large kine- matic isotope shifts in accelerated atoms moving collinearly with the laser beam. For atoms such as 3He having high ionization potentials metastable neutrals are first produced by charge exchange between the atomic ion and a suitable metal vapour.A tradition in the RIS symposium is to invite speakers to represent non- RIS methods for difficult analytical problems. This year Martin Suter Paul Scherrer Institut Zurich Switzer- land gave a plenary lecture on an accelerator mass spectrometer for rare isotopes such as l0Be and 14C. This method uses very mature technology as compared with RIS and sets a high standard for the detection of rare species such as 14C. Applications of RIS to Materials Science N. Thonnard Atom Sciences Oak Ridge TN USA outlined the devel- opment of the analytical capabilities for the analysis of surfaces and the bulk characterization of materials by depth profiling using the sputter- initiated RIS technique known as SIRIS. This technique pioneered by J.E Parks and others at Atom Sciences and by N. Winograd at Pennsylvania State University has some features in common with the well-known SIMS method. However in SIRIS the secon- dary ions generated by the impact of the ion beams on the surface are not the signal of interest; it is rather the signal generated by RIS on the sput- tered neutral atoms. The central idea in this more complex instrument is that the analysis of impurities in ma- terials should be more sensitive and relatively free of matrix effects com- pared with SIMS. That these features can be advantageous was dramatically demonstrated by S. W. Downey AT&T Bell Laboratories Murray Hill NJ USA. Dr. Downey showed results for the depth profiling of Be atoms at the interfaces of GaAs-A1As and InGaAs-InAIAs structures.The clean features of these interfaces are not seen nearly so well with the SIMS technique where large matrix effects obscure the boundaries. Equally impressive results using the SIRIS technique were re- ported by George Havrilla BP Re- search Cleveland OH USA on the analysis of silver-gold structures where again drastic improvements in the definition of boundaries was ob- served and was attributed to reduced matrix effects. Dr. Matthew H. Ervin with the Winograd group reported some fasci- nating studies of polycyclic aromatic compounds and several molecules of biological interest which were deposi- ted on the upper layer of solids. These molecules could be photo-desorbed in a process described as ‘gentle’ such that the released molecules were neu- tral and intact.Further when the RIS process was used to ionize these mainly the parent positive ion was found. These strikingly clean results have led to an analytical system with sensitivity at the ferntomole level. Environmental and Trace Analysis Because of pressing applications new developments in trace analysis espe- cially for environmental applications is taking place at a rapid rate. The well-known approach at the Institute of Spectroscopy at Troitsk in which a graphite furnace is used as the atom- izer was reviewed by George Bekov. The free atoms are then stepwise ex- cited in resonance processes to a Rydberg state where field ionization occurs. High sensitivity efficient atomization and other features were described that show laser analytical photoionization spectrometry (LAPIS) is capable of handling a wide variety of environmental problems.R. Zilliacus Technical Research Centre of Finland studied the problem of precision using a system similar to the LAPIS system of Bekov. Of special attention is the matrix effect which is smaller with the graphite furnace than many other types of ionizers. The group in Finland (Zilliacus Likonen and Auterinen) is making progress using various tricks of chemical modification to achieve precisions of a few per cent. For several years the KIS group at Tsin- ghua University has been developing an analytical system for the direct analysis of gold and other precious metals in minerals. At RIS-90 the authors (Hui Niu Cheng Xu and Zhao under the direction of D. Y . Chen) reported on a spectacular sensi- tivity for the analysis of gold in miner- als.They find detection limits of 10 ppt with backgrounds of the same order. The Tsinghua group uses a thermal atomizer followed by three resonance steps the last being an auto- ionization level. Not all trace analysis belongs to the environmental areas. H. Lauranto Helsinki University of Technology Finland discussed the use of RIS to measure the neutron dose in pressure vessels of nuclear reactors. The idea is to measure the concentration of the nuclear isomeric state compared with the nuclear ground state of 93Nb which increases in direct proportion to the neutron flux that can embrittle the vessel. A RIS scheme for distinguish- ing the two nuclear states based on hyperfine splitting of certain optical levels was presented.F. Ames Universitat Mainz Ger- many along with his colleagues at Mainz and the Bhabba Atomic Re- search Centre Bombay India devel- oped a RIMS system for the measure- ment of the 8B solar neutrino flux. The special feature of this experiment pur- sued also at Los Alamos National Laboratory is that it would measure the neutrino flux integrated over the past several million years and would thus test the constancy of the sun. The method requires the analysis of about 1 x I O8 atoms of 9 7 T ~ or 9 8 T ~ along with about 1 x 10’ atoms of 99Tc and about 1 x lo1* atoms of Mo. An ingenious furnace was developed such that when operated at 2300 K the atoms to be detected would be confined inside a cavity where they cross the RIS beam many times.Ions extracted from the cavity were mass analysed with a high resolution mass spectrometer. A novel method for the direct analy- sis of semiconducting materials using LEI was developed and presented by N. V. Chekalin V. I. Verdansky Insti- tute of Geochemistry and Analytical Chemistry Moscow USSR. This so- called ‘rod-flame’ method uses a confi- guration in which the sample can be directly evaporated from a graphite rod into a flame where atomization of the sample and where the LEI process occurs on the thermally dissociated atoms. The rod-flame method is 3-4 orders of magnitude more sensitive than conventional atomic absorption in flames. R. D. Willis Atom Sciences re- ported on the use of RIS to measure 81Kr in lunar rocks and meteorites. A method for measuring cosmic-ray ex- posure ages of such materials has been pioneered by Professor 0.Eugster University of Bern Switzerland in which a mass spectrometer is used to measure 81Kr along with at least one cosmogenic stable isotope of Kr and from the ratio the exposure age is calculated. A measurement was made at Bern by Eugster Th. Michel and B. E. Lehmann using a special mass spec- trometer and a measurement was made in Oak Ridge using RIS in a TOF mass spectrometer. The agree- ment on the exposure age (more thanJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 409 The Russian delegation of scientists clearly en.jo-ving themselves at the Conference Dinner on Thursday evening 20 million years) was excellent even when the sample measured at Atom Sciences was about 50 times smaller than that of the Bern measurement.The pay-off in using RIS is that much smaller sample sizes can be used perhaps by more than two orders of magnitude. Biological and Medical Applications Progress on the application of RIS and other laser methods to biological and medical problems continues. In a ple- nary lecture Professor Sune Svanberg Lund Institute of Technology Lund Sweden reviewed the use of laser spectroscopy such as coherent and anti-Stokes Raman scattering laser induced fluorescence and others in the mapping and quantification of atmos- pheric pollution. In medicine lasers are used to detect cancer in addition to photochemically treating them. Fol- lowing the injection of tumour-seeking agents lasers can be used to induce fluorescence in the diseased areas.By using time-gated optical illumination of the tissue with picosecond laser pulses blurring as a result of scattering can be reduced giving new possibili- ties for mammography with non-ioniz- ing radiation. I. K. Perera and colleagues at Uppsala University Uppsala Sweden reported progress on the use of UV lasers to desorb and ionize large mole- cules of biological interest. These ions are then analysed with a TOF mass spectrometer up to a mass range of 200000 u to study peptides polypep- tides and proteins. The RIMS technique is making im- portant contributions to diabetes hae- matology toxicology neonatology and neurology by analysis of trace elements such as chromium iron copper nickel and molybdenum. These results were reported by L.J. Moore Eastern Ana- lytical College Park MD and repre- sent a collaboration with Atom Sci- ences in Oak Ridge. Another significant contribution to the biological sciences is being made by H. F. Arlinghaus and his colleagues at Atom Sciences in their teaming with K. B. Jacobson of Oak Ridge National Laboratory to develop a much more rapid sequencing technique for the human genome. The approach is to label the four nucleotide bases with stable isotopes and to detect these isotopes using RIS in the SIRIS sys- tem. Encouraging results show that by speeding up the analysis with the high pulse rates of a Cu-vapour laser it should be possible to process 10 mil- lion base pairs per day and thus an entire genome could be sequenced in one year. Molecular Studies Many of us would not have predicted that laser ionization of large mole- cules would ever produce the beau- tiful results that were presented at Varese.For instance J. Grotemeyer Garching Germany uses a wide range of laser wavelengths to desorb and ionize molecules such as amino acids proteins nucleotides and pep- tides. Supersonic jets were used to keep the neutral molecules intact. The RIMS studies of naphthalene toluene and aniline were reported by A. Marshall University of Glasgow UK. Some very interesting results were discussed by U. Boesl Universi- tat Munchen Garching Germany. By Jim Parks congratulates Mohamed El- Maazawi winner of the Poster Award. The work was carried out at the Pennsylvania State University under the direction of Professor N.Winograd Roland Hergenroder student to Professor Niemax receives the congratulations of Jim Parks (lefl) and Sam Hurst (centre) as the recipient of the Graduate Student Award. The ceremony took place during the Social Dinner using benzene as an example it was shown that the multiphoton ioniza- tion of large molecules can occur in a sequence called ‘ladder-switching’ in which ion dissociation can be so fast that further absorption takes place in a fragment which further dissociates and so on to propagate the sequence.410 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 Awards Two awards were made at RIS-90. One of these was for the best work per- formed and presented at the sympo- sium by a graduate student. Another award was for the best poster and was open to all participants.The Award for best poster presentation was made to Mohamed El-Maazawi who happened to also be a graduate student. Along with the honour Dr. El-Maazawi re- ceived a cash prize of US$200.00 provideq by an anonymous donor and copies of the books by Professor Leto- khov on ‘Laser Ionization Spectro- scopy’ and Hurst and Payne on ‘Reso- nance Ionization Spectroscopy’. For the Graduate Student Award there were 10 entries and all of them represented excellent work. The judg- ing committee was very impressed and took the evaluation process very seri- ously. At the social dinner the top three places were recognized. In third place was Q. Hui a student of Professor D. Y. Chen at Tsinghua University in Beijing People’s Repub- lic of China.The title of this work was ‘Ultrasensitive Analysis of Gold in Mineral Samples Using Resonance Excitation and Auto-ionization Mass Spectrometry’. In second place was F. Ames a student of H. J. Kluge Universitat Mainz with an entry entitled ‘RIS of Technetium in a Laser Ion Source for a So1a.r-Neutrino Exper- iment’. However the Award went to Roland Hergenroder a student of K. Niemax Institut fur Spektrochemie und angewandte Spektroskopie. The Award was made for the development of the ‘Continuous Wave Field Ioniza- tion Laser Spectrometer’. For this out- st anding contribution Dr . Hergenro- der received a plaque and a cash prize of US$lOOO provided by the Institute of Resonance Ionization Spectro- scopy Physics Department Univer- sity of Tennessee. Thanks are due to the many spon- sors for their financial and moral support.These were CNR Comitato Nazionale Scienze Chimiche; ENEA; Istituto Nazionale Fisica Nucleare; Environment Institute JRC Ispra; dB Electronics; Elicam; ISA Italia; Laser Optronic; Microcontrole; VG Instru- ments; Atom Sciences; US Depart- ment of Energy Office of Health and Environmental Research; Battelle Pacific Northwest L,aboratories Mole- cular Sciences Research Center; EG & G Energy Measurements; Los Alamos National Laboratory; Martin Marietta Energy Systems; Perkin-Elmer Physi- cal Electronics Division; National Institute of Standards and Techno- logy; and the Institute of Resonance Ionization Spectroscopy and the Sci- ence Alliance of The University of Tennessee. The continued interest of the US Department of Energy and especially the strong interest and leadership provided by Gerald Goldstein of the Office of Health and Environmental Research is much ap- preciated.The complete proceedings of RIS-90 are available from IOP Publishing Bristol UK. The RIS-92 is planned for May 24-29 1992 Santa Fe New Mexico. Those interested in further informa- tion should contact the Institute of RIS or C. M. Miller at Los Alamos National Laboratory. One of the main goals is to continue the strong partici- pation of graduate students which started at Varese through the efforts of Professor Omenetto. The Graduate Student Award and the Poster Award will be a continuing part of the sym- posia. Tutti si sono divertiti moltissimo! G. Samuel Hurst Institute of Resonance Ionization Spectroscopy 10521 Research Drive Suite 300 Knoxville TN 37932 USA XXVll CSI Pre-Symposium on Graphite Atomizer Techniques in Analytical Spectroscopy June 6th-8th 1991 Hotel Ullensvang Lofthus Norway I have to admit that after nearly two months of non-stop travel and having only two days before the start of the pre-Symposium flown back from Ja- pan the thought of travelling to Nor- way for the CSI meeting was not one I viewed with any enthusiasm. The all day journey culminating in a four hour bus transfer from Bergen to Lofthus on narrow twisting roads along the Nor- wegian Fjords (what no parrots?) did not auger well.However both myself and the other participants (approxi- mately 120) were to be rewarded with what in my opinion was one of the best electrothermal atomization meet- ings that I have attended in the last 4-5 years.The organizers Bernhard Welz and Wolfgang Frech are to be roundly congratulated for such a wide ranging and informative meeting. They also introduced several new sym- posium management techniques that I feel sure will become accepted practise in the future. The first requirement is to organize the meeting in a good hotel in an area Bernhard U’ek om7 of the con-krence organizers in a more relaxed monieiit of outstanding natural beauty which has a high propensity for torrential rainfall in the summer. This ensures an almost 100°/o attendance at all of the lectures. Secondly ensure that the final speaker of each session is the Chair- man of that session. This concentrates the mind of the Chairman on making sure that everyone keeps to time as both myself and Chris Mullins dis- covered.Thirdly organize the meeting in a country where alcohol is prohibi- tively expensive this guarantees that everyone will be on time for the first lecture of the day. Finally ensure that the sun comes out in time for the excursion tour. Without a shadow of a doubt Drs. Welz and Frech have set the organizational standards against which all other future meetings will be measured. The meeting was opened on the Thursday morning by Sir Alan Walsh who apologized for never having used an atomic absorption instrument with a graphite electrothermal atomizer but that he had realized the feasibility of the technique for absolute analysis early on which had subsequently been demonstrated and expanded on by Professor L’vov.The first half of the morning session was comprised of a series of lectures examining the structure and nature of reactions on the surface of graphite. Professor Yang (State University ofJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 41 1 New York at Buffalo) gave a fascinat- ing lecture entitled ‘Electron Micros- copy Study of Gas-Carbon Reactions’ which considered the probable nature of reactions between metal atoms and the edge carbons of the graphite crystal plane at elevated temperatures in the presence of water carbon dioxide and oxygen. Some stunning electron mi- crographs were shown of metal par- ticles ‘eating’ their way in a regular fashion along the edge carbons which might be a result of the carbon dissolv- ing into the metal droplet which ‘pulls’ the metal particle along.This was followed by Professor Ortner (Techni- cal University of Darmstadt) with his lecture ‘Materials in ETAAS-a struc- tural and morphological review’ which examined graphite surfaces on a slightly larger scale but illustrated how important the microstructure of the graphite surface is in terms of its lifetime. Following these two lectures what turned out to be the ‘hot topic’ of the meeting was introduced by Professor Boris L‘vov (Leningrad State Techni- cal University) with his lecture ‘Gase- ous Carbide Concept in GFAAS State of the Art’. A review of the develop- ment of the theory and the author’s experimental evidence contrasted with a differing interpretation of recent results published by Holcombe et al.This prompted a heated debate which was continued in a discussion later that evening. The next two lectures discussed the opposing theories on the subject of reduction by gaseous car- bides. Dr. Dave Styris (Pacific North- west Laboratory) with ‘Atomization Mechanisms from Real-Time Gas Phase Mass Spectra Clues from Car- bides and Oxides’ discussed the differ- ences between vacuum and atmo- spheric vaporization. If both of these are performed then one can separate out the gas phase from the surface effects. From his studies he concluded that the atomization mechanisms of In Ga and A1 were a result of thermal decomposition. Following on from this came Professor Jim Holcombe (University of Texas) with ‘Alumi- nium Spikes and Mechanisms for Alu- minium Vaporization’.This intensi- fied the debate as Jim Holcombe pre- sented his and his co-workers interpre- tation of the spikes sometimes formed by the atomization of large amounts of A1 in a graphite electrothermal atom- izer. However there were no dissent- ing voices when Jim Holcombe stated that ‘spikes are fascinating’ he went on to say that the generation of spikes is frustrating and that in his opinion the direct observation of spikes does not support the gaseous carbide theory and that there are so many dependent variables that everything is very con- fusing. A conclusion that nobody in the audience at Lofthus would disagree with. He presented a range of results from mass spectra studies to those from Monte Carlo modelling and ended up by presenting more ques- tions than answers.However the lec- ture stimulated a considerable discus- sion as only now is the gaseous carbide theory being rigorously examined by a variety of groups around the world. The results of all of these investiga- tions can only be to improve our understanding of what is happening within a graphite electrothermal atom- izer for which Professor L‘vov and his theory of gaseous carbide reduction has been the catalyst. To conclude the first mornings session Dr. Gilmutdi- nov (University of Kazan USSR) pre- sented his teams work on ‘Dynamics of Atomic and Molecular Layers in Graphite Furnace AAS’. The distribu- tion and generation of atomic and Time for a break during the poster session Boris L ’vov Dave Styris Debbie Bradshaw and Jim Harnly molecular layers during the atomiza- tion stage in a graphite atomizer were examined using shadow spectral film- ing.Some very interesting results were presented showing atomization from both the wall and the platform for a variety of elements and showed strong non-uniform distributions across the atomizer which depended upon the element. Both sides in the discussions used the data to support their own particular interpretation. By now it was time for lunch and the partici- pants walked stunned into the hotel restaurant. This had to be one of the most stimulating mornings collection of papers I had ever experienced and the general consensus gained during lunchtime discussions confirmed these feelings. The afternoon session continued with more mechanistic considerations with Professor Cor Rademeyer (University of Pretoria) considering the atomization mechanism of silicon in the presence of oxygen and carbon monoxide.This was nicely followed with Dr. Wend1 (University of Karls- ruhe) considering the role of oxygen in the determination of oxide forming elements such as T1 Bi Cd and Pb. On a slightly different tack Dr. Huie (State University of New York at Binghamton) presented results exam- ining the gas dynamics in a graphite atomizer using the absorption from Na and laser sources. The laminar and turbulent gas flows in a transparent cylindrical glass tube with the same dimensions as a graphite atomizer were assessed although as a number of questions pointed out his experi- ments were performed at room tem- perature which is somewhat different to the real situation however the information was valuable.Dr. Douglas Baxter (University of Umeii) made a stunning entry from the back of the lecture theatre in complete traditional Scottish dress and presented his results on assessing the spatial distribution and partial pressures of Cz and CN molecules in an integrated contact atomizer. Douglas was to be congratu- lated on starting his lecture with a geography lesson showing a sketch map of where we were in Norway and where Umeii is in relation to Lofthus. I was indebted to this overhead as up until that point I had no idea of where I was in relation to the rest of Norway although the worst question of the meeting had to be ‘Do all Scotsmen wear dresses?’ Dr. Yasuda (Hitachi) then presented some work on measur- ing gas temperatures in a graphite atomizer using the ‘two-line’ method which is now accepted as only giving an approximate measure of the aver- age temperature in the atomizer. The afternoon session was concluded by Dr.Marowsky (Max-Plank Institute for Biophysical Chemistry) who dis- cussed the information that can be extracted from gas phase systems (such as temperature measurements) using non-linear optics and the fact that degenerate four-wave mixing provides much better detection sensitivity than that of non-resonant CARS. As a very non-physical chemist I was prepared to take his word however there is no denying Dr. Marowsky’s enthusiasm for his subject and during a subsequent lunchtime discussion he convinced me that he could solve all our problems with laser beams.But as always it is a question of time and money. The evening discussion with the provocative title of ‘Modelling of Graphite Furnace Processes What Do We Know?’ rapidly moved on from the suggested topic of modelling to that of the reduction by gaseous car- bides. In the blue corner we had Professor Boris L‘vov and in the red corner Professor Jim Holcombe and412 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 we the assembled throng waited with baited breath for the heavyweights to slug it out! It rapidly became clear that there are no firm protocols or ideas on how to investigate atomization mecha- nisms or interference mechanisms and that without further evidence we are left with interpretation of experimental data which can often be conflicting depending upon the starting point or opinions of the individual scientist.The discussion was ably led by Wolf- gang Frech who bravely kept the whole thing under control and the evening was notable for the two occasions when Jim Holcombe said that he agreed with Boris L'vov on particular points. 'Is this possible' asked the assembled masses? (An abridged version of the discussion will appear in the confer- ence issue of JAAS next March.) Following the main discussion a small group of well-known scientists were seen later to be huddled in a corner until the small hours of the morning discussing believe it or not gaseous reduction by carbides. Another not so well-known group re- tired to the back of the lecture theatre and with the aid of some not inconsi- derable amounts of imported duty free liquor discussed deep and meaningful questions such as the probability of whether it would continue to rain on the following day and whether any programme session could ever hope to finish on time? Only experience would tell as an extremely nervous future Chairman wound his weary way to bed! The Friday morning session was devoted to combined techniques and featured presentations from Dr.Welz (Bodenseewerk Perkin-Elmer) and Professor Fang (Academica Sinica Shenyang China) on flow-injection on-line preconcentration procedures coupled with a graphite electrothermal atomizer. This is a technique that seems to be increasing in popularity and offers a relatively contamination- free method of improving detection limits and extending the range of ETAAS analysis to lower levels.These two lectures were complemented by those of Walter Slavin (Perkin-Elmer) and Professor Ni (Academica Sinica Beijing China) who considered the trapping of gaseous hydrides and alkyl- selenides within a graphite electrother- mal atomizer. Professor Ni described the coupling of GC with ETAAS for the determination of alkylselenides. The alkylselenides were separated by gas chromatography and the eluted species led directly into a palladium coated graphite tube and trapped at a temperature of 500-600 "C. There appeared to be sufficient time for the operation of the furnace programme during the time interval between each elution peak. Dr. de Loos-Vollebregt (Technical University Delft) con- tinued with this theme and discussed the speciation of organo-metal com- pounds with HPLC-thermospray coupled with a graphite electrothermal atomizer. Professor Chakrabarti (Car- leton University Canada) then consi- dered the use of electrothermal vapori- zation coupled with ICP-MS to inves- tigate the chloride interferences in graphite electrothermal atomizer AAS on the determination of Mn in 1% HC1.The fact that wall atomization was used for the investigation when this interference can be overcome by the use of a platform and/or chemical modification was the subject of some pertinent questioning. To conclude the mornings session the Chairman (the Presentation to Bruno Hiitsch The poster session author of this report) described the development and application of an instrument using the longitudinal Zee- man-effect for background correction combined with a transverse heated graphite electrothermal atomizer.The afternoon session was devoted to viewing the posters of which 50 were presented and sub-divided into the following subject areas separation preconcentration and sequestration; instrumental developments; reaction and atomization mechanisms and modelling; solid samples and slurries; interferences and modifiers; and last but not least applications. An ex- tremely wide range of posters were presented and most of the participants spent the entire afternoon in detailed discussion with the various authors although the steady and persistent rainfall might have had something to do with this.Both before and after the evening meal group discussion sessions were organized concerning the posters. The evening poster discussions were pre- ceeded by a presentation of a gold graphite tube with a diamond injec- tion hole in the form of a tie pin and an accompanying certificate signed by the participants. They were awarded to Bruno Hutsch of Ringsdorff GmbH as a small token of the appreciation for all his help and assistance over the years with the fabrication of all of the myriad different graphite tube and platform designs that many of us have required for our research and often obtained at no expense. Following the presentation Dr. Gilmutdinov showed actual film of some of his shadow spectral results. These results certainly stimulated some thoughts as to what we were really observing in a graphite atomizer.The range of subjects and areas considered by the posters was large and only a flavour can be given here. Clearly the subject of speciation is one that is starting to receive serious attention not only from the point of analyticalJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 413 methodology but from the more se- rious aspect of what are we really measuring? How can we be sure that we are not disturbing the equilibrium of the various species? All present agreed that quality control samples are needed with certified values for differ- ent species. The hardy perennial of standardization in slurry and solid sampling was once again discussed. With multi-element techniques inter- nal standardization can be used but one has to confirm that it works.Some discussion centred on the limitations of the Zeeman-effect for background correction especially when small mole- cules such as PO are present. However it was concluded that while there are certain situations where there are problems with Zeeman-effect back- ground correction these are very rare and hence it is still the best method. During the evening discussion the topic of nomenclature reared its mal- ign head courtesy of Bernhard Welz and considerable time was devoted to the discussion of what symbol we should use for integrated absorbance? The term As is false as integrated absorbance is a dimensionless unit but with this terminology the units should be seconds. The term A has been proposed for peak absorbance and discussion centred on the use of A,nt for integrated absorption.Just to round off the evening we were all told that we should stop using the term furnace and that IUPAC recommends the term atomizer. Therefore in the preparation of this report I have tried to use the term atomizer throughout. Saturday morning and the start of the final session was greeted with sunshine much to our amazement Even though Dr. Yngvar Thomassen had promised us all fine weather for the Saturday afternoon excursion most of us had considered that this was wishful thinking on his part or that he had a direct line to God. It would appear that the latter was correct. The final session was devoted to the exami- nation of some of the new techniques being developed involving the use of graphite atomizers as a source of either atoms or ions for emission measure- ments.Professor Mike Blades (Univer- sity of British Columbia) started with a discussion of the ‘Recent Develop- ments in Furnace Atomization Plasma Excitation Spectroscopy’. The FAPES source has the potential for carrying out simultaneous multi-element analy- sis and Mike described his system which uses an isothermal side-heated graphite atomizer with a central graph- ite rod powered by a radiofrequency generator enabling the formation of plasmas at atmospheric pressure. The system is flexible and allows a compar- ison of both atomic emission and absorption signals. Dr. Ralph Sturgeon (National Research Council of Canada) discussed the use of the FAPES source to examine molecular species and to assess the effects of modifiers on these species in an effort to provide more information about what is happening during atomization in a graphite atomizer.The multi- element theme was expanded by Dr. Jim Harnly (United States Depart- ment of Agriculture) who presented work on the various techniques used to improve the performance of contin- uum source AAS. These included an improved optical configuration pho- todiode array detection in conjunction with a larger spectral bandpass and pulsing of the xenon arc continuum source. Dr. Heinz Falk (Spectro Ana- lytical Instruments) discussed the ‘Ul- trasensitive Detection of Atoms and Ions using Graphite Furnaces’ and indulged in a little bit of crystal ball gazing to consider the possibilities of single atom detection using laser exci- tation and trapping within graphite atomizers.Although feasible in princi- ple I noted the wry irony in Dr. Falk’s voice when he concluded that the level of experimental expenditure to de- monstrate this would be high! The potential of ‘Laser Induced Flu- orescence (LIF) Spectrometry as an Analytical and Diagnostic Tool in Graphite Atomizers’ was presented by Dr. Sten Sjostrom (Chalmers Univer- sity of Technology). This technique has detection limits in the femtogram range high selectivity and a large dynamic range and in the opinion of Dr. Sjostrom is justified for demand- ing ultratrace analyses. Although a major limitation appears to be the availability of cheaper lasers covering a wider wavelength range. The penulti- mate lecture was presented by Dr.Ken Jackson (State University of New York) on the ‘Physical and Chemical Mechanisms of Modifiers in Slurry ETAAS’ however he decided to re- name his lecture ‘Only God Knows How Pd Works as a Modifier’ in response to comments made the previ- ous day by Professor Chakrabarti con- cerning what goes on in an atomizer (maybe he should talk to Yngvar?). Palladium is widely accepted as a modifier however its mechanism of action in slurry analysis has not been widely investigated and results indi- cating a more physical than chemical effect were shown. The concluding lecture was from Dr. Chris Mullins (Varian) on the determination of man- ganese in urine using platform atomi- zation and preconcentration via mul- tiple injections. After such an arduous two and a half days of lectures a half day excursion was organized to enable us to relax unwind and admire the spectacular Norwegian countryside.I make no apologies for these gushing sentences as they are lifted directly from the symposium programme. I am certain that if Drs. Welz and Frech grow tired of science then they are assured of a successful future as advertising copy writers. (The money cannot be any worse!) Following a pleasant after lunch stroll in glorious sunshine round the small village of Lofthus (some brave souls even ventured by rowing boat onto the fiord) and entertainment by the local marching bands we boarded the buses for our visit to the Hardangervidda the largest mountain plateau in Northern Europe. Along the way we stopped at the Sima electricity generating plant which is built 700 m inside the mountain side at Eidfjord where we were shown an interesting film about the construction of the power plant.Heavy snowfall takes on a whole new meaning when you see pictures of ‘dwarf-like’ snow blowers attempting to cut through 10 m high snow drifts! From here we climbed slowly up to the Voringsfoss waterfall. This steep twisting road had me wish- ing that I had brought my motorcycle to Norway. The Voringsfoss waterfall has a free fall of over 183 m and is certainly spectacular. What was also entertaining was to see the look of absolute horror on the face of our tour guide as over 120 people scrambled to the very edge of the ravine to get good photographs clambered all over the wet slippery rocks and generally took more risks than he would have liked.I am certain that he had visions of seeing more than one person go Enjoying Saturday afternoon ’s excursion Barbara Dittrich (Leipzig Germany) and Marcella Sucmanowa (Brno Czecho- slovakia)414 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 through a ‘birdman-crater (or splash!)- total’ sequence. Fortunately we all returned safely to the buses although I had tried to convince Ken Jackson that throwing himself into the ravine would have made a spectacular picture for this JAAS report and would assure him of a legendary status within our community. From here we continued up to the plateau and marvelled at the amount of snow still on the ground before stopping at the Halne Mountain Lodge where we were served a superb buffet of typical Norwegian hot and cold dishes.Those of us with some experience in these matters made straight for the reindeer goulash the enormous smoked salmon and the Norwegian sweet porridge with cinna- mon which is eaten as a dessert. This delightful though not terribly inter- esting looking dish became a firm favourite with a small select group of aficionados. Following our return journey the final evening ended up with a considerable number of the participants taking over the hotel foyer and indulging in a late night inter- national joke-telling competition with notable contributions from Jim Harnly for ‘The Gorilla Story’ Nancy Miller-Ihli for ‘The Wendy tale’ and a seemingly never ending stream of jokes from Mike Blades.Social highlights of the meeting were the phenomenal drinking exploits of a couple of English scientists who shall remain nameless although they wish to apologize publicly to Zvone Gro- benski for drinking his bottle of slivo- vitz. Dr. Grobenski organized the early morning jogging sessions which sadly I missed due to Phil Riby keep- ing me up past my bed-time! Most people also missed the disgusting early morning spectacle of a relatively young English scientist being abso- lutely thrashed at squash by a well- known Texan Professor of Chemistry. The final seven hour coach journey back to Bergen for the CSI meeting was enlivened for the people at the back of our bus as one participant and a well-known journal editor indulged in what is euphemistically known to the English as ‘jovial banter’ but to those in the near vicinity who are unaware of this custom may have appeared to be some form of ritualistic verbal abuse normally carried out be- tween sworn enemies. Throughout the three days of this symposium stimulating ideas were presented new directions examined and I went away with my intellectual batteries recharged my liver crying out for a rest and total panic taking hold every time I thought about how I was going to write about all these lectures for next years ASU review.In conclusion I would once again like to thank the organizers for an excellent meeting. From both a scientific and social point of view we all had a very enjoyable time. I look forward to seeing everyone at the next ETAAS Post-CSI symposium somewhere in Northern England in 1993.Who- ever convinced me to organize this has no idea of how hard it is going to be to follow such an impressive act.. . Ian L. Shuttler Bodenseewerk Perkin-Elmer GrnbH Uberlingen Germany XXVll Colloquium Spectroscopicurn Grieg Hall Bergen Norway Internationale Continuing in the tradition of the CSI meetings the XXVII in Bergen Nor- way afforded an opportunity for ana- lytical spectroscopists from around the world both to learn of the latest devel- opments and to discuss them with their peers. The CSI is truly the most international of analytical spectros- copy meetings and on this occasion 27 countries were represented. What bet- ter place to become acquainted with the person whose name you know so well from their published work.And then there are old friends ever willing to discuss their latest ideas and to share in the pleasures of the social gatherings. The main conference venue was the Grieg Hall in Bergen where the plenary lectures and poster sessions were given and which housed the instrument exhi- bition. The contributed papers were organized into six parallel sessions which were presented in the lecture theatres of the University a few min- utes walk away from the Grieg Hall. The scientific programme covered all of the major branches of analytical spectroscopy including optical X-ray mass NMR and electron spectrome- try. The two opening plenaries dealt with sources somewhat larger than those normally encountered in the analytical laboratory namely stars and inter-stellar clouds.Analytical spec- troscopists familiar ,with using wave- length or mass tables to identify the presence of particular species will feel fortunate in not having to interpret spectra that have been Doppler shifted to unfamiliar wavelengths. Here the wavelength separations and intensity ratios become the key identifiers and it is perhaps not surprising that the use of multi-pixel detectors pioneered in astronomy are now beginning to have an impact in analytical spectroscopy. An unusual feature of this meeting was that the mornings were largely given over to plenaries a total of eighteen being presented. These included con- tributions on environmental applica- tions atomic and molecular spectros- copy surface techniques and chemo- metrics. There were 167 contributed papers and 255 posters falling broadly into these categories but also included were many on sample preparation techniques and the use of spectros- copic detectors coupled directly to either preconcentration or chromato- graphy systems.An important part of the contem- porary CSI meetings are the pre- and post-symposia. Three were organized in Norway on the following Graphite June 9th-l4th 1991 Atomizer Techniques; Measurements of Radionuclides after Chernobyl; and Speciation of Elements in Environ- mental and Biological Sciences. Large numbers of delegates attend these meetings and they are undoubtedly major contributors to the success of the over-all event. There is however some evidence that many scientists attend only the peripheral meetings and this undoubtedly detracts from the main event.Traditionalists may Sir Alan Walsh receives his award fiom Adam HulanickiJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 41 5 regret this but it certainly reflects trends elsewhere where specialist meetings have grown at the expense of those covering a broad range of sub- jects. Future CSI organizers will have to consider this point carefully. Cer- tainly those of us concerned with the next CSI in York will try to strike an appropriate balance. Perhaps some time in the future an organizing com- mittee will offer an entirely decentral- ized CSI but then will it be the CSI? A new event departure at this CSI was the introduction of a CSI Award for major scientific contributions to analytical spectroscopy. The recipient was Sir Alan Walsh and there were tributes from L.R. P. Butler P. Lar- kins and R. Sturgeon. Sir Alan’s scien- tific achievements are well known but we heard of a humble man whose infectious enthusiasm and advocacy helped to bring atomic absorption spectrometry to the benefit of the analytical community and the world at A detailed discussion of the week’s events held at an informal meeting near Bergen harbour large. One story told of how in the very early days of atomic absorption Awaiting the train to Flam during the Wednesday excursion Admiring the scenery. Left to right Mikhail Bolshov Adam Hulanicki Manfred Gras- serbauer and Zhaolung Fang A welcome stop on the coach journey back to Bergen. Left to right Yngvar Thomassen (conference organizer) Ian Brindle Julian Tyson and Helen Crews On board the catamaran.Left to right Richard Ediger Jim Crighton John Dean Sheryl Whitewood Barry Sharp Sam Houk and Carmen Huie416 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 When the dancing had to stop there was always the scenery to admire and the ramp was an ideal vantage point. Lejt to right Sheryl Whitewood Phil Riby Debbie Bradshaw Joanne King Ian Brindle and Mike Hinds Definitely the stars of the show Sir Alan and Lady Walsh enjoying the dancing at the Conference Farewell Party The transport really was a car ferry but that didn’t stop anyone from enjoying themselves The US contingent however were a close second when it came to putting on a show. Left to right Dorothy Barnes Susan and Gary Hieftje the life of a young boy suffering from Mg deficiency was saved following an analysis of his blood. A fitting tribute to this most humane of men.But what now? Speaking personally I do hope that future organizers will not feel obliged to make an award lest they devalue those that have gone before or burden their committees with a ‘whose turn is it next?’ decision. The city of Bergen is situated on Norway’s spectacular West Coast where a never ending vista of sea Gords and mountains capture both the eye and the imagination. Several ex- The North American ‘Spectroscopists’ Choir singing Rudolfthe Red Nosed Reindeer at the Tuesday evening cheese and wineJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 417 cursions were available to cater for all tastes the most popular being the Norway in a Nutshell tour.Delegates were taken by train through deep valleys hiding under snow-capped mountains past thundering waterfalls and tumbling rivers to the town of Ham. Here we boarded a catamaran which took us along the Aulandsfjord and into the Naeroyfjord one of the narrowest in Western Norway. The scenic tour continued by coach follow- ing roads that clung precipitously to rock ledges hewn from the mountain- sides which plunged into the cold blue water. I was strongly reminded of the West Coast of Scotland but the scale was larger and the alpine architecture gave the scene a fairyland feeling. Just the place to meet a troll one of Norway’s mythical gremlins and well known to users of scientific instru- ments everywhere.In addition to the excursions there was opportunity to sample Norway’s musical and cultural heritage with the music of Grieg as the focal point. Music of a different kind provided the entertainment at the final social event. For this the organizers hired a car ferry for an evening tour of the waterways around Bergen. The open air car deck provided the dance floor whilst in the saloons plentiful supplies of prawns and beer kept the delegates fuelled for the evening’s activities. Purists might regard steel plating as only suitable for tap dancing but analytical spectroscopists are necessa- rily a hardy race and there were some noteworthy performances. Not all of which were necessarily related to the dancing. And so to York where you are invited to attend the XXVIII CSI on June 29th-July 4th 1993. The confer- ence will be held at the University of York a modem campus offering excel- lent facilities on a compact site. The scientific programme will be organized into four main sessions dealing with Tibor Kantor leading the East European Choir in response (a few extras helped out including on the far right Pat Styris) atomic molecular and mass spectro- metry and surface science. Days will begin with a plenary session and then divide into four parallel streams each beginning with an invited lecture. Afternoon sessions will begin in a similar fashion but the remainder of the afternoon will be given over to poster presentations. There will again be a series of pre- and post-symposia and also workshops. The list of these is not yet complete but electrothermal atomization inductively coupled plasma mass spectrometry glow dis- charge spectrometry data transfer in spectroscopy and chemometrics will be included. The ancient walled city of York is full of attractions for the tourist York Minster the largest Gothic cathedral in Northern Europe; the Castle Mu- seum; the Jorvik Viking Centre; the National Railway Museum; and many more. It also provides excellent shop- ping areas and is a centre for the antiquarian book trade. Close to the city country houses such as Castle Howard and Skipton Castle are open to the public. The Yorkshire moors and the many attractive towns and villages of the Yorkshire coastline are also nearby. An aim of the Organizing Commit- tee is to keep costs to a minimum in order to enable as many scientists and students as possible to attend. For this reason the conference will be offered at a price which includes accommoda- tion in the University halls of resi- dence. If you require further informa- tion this is available from the Con- ference Secretariat Department of Chemistry Loughborough University of Technology Loughborough Lei- cestershire LE11 3TU UK. Barry L. Sharp Loughborough University of Technology Lough borough UK

ISSN:0267-9477    

DOI:10.1039/JA9910600406

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY7 SEPTEMBER 199 1 VOL. 6 417 Conferences and Meetings 1992 Winter Conference on Flow Injec- tion Analysis (WCFIA 92) January 12-1 5 1992 Embassy Suites Resort Hotel Scottsdale Arizona USA Flow injection analysis techniques are being used in many laboratories throughout the world. Although the idea of injecting a sample has been around for many years the concept of controllable dispersion is only starting to be more clearly understood. As a result FIA is being viewed as an alternative that can simplify analyses which previously were time consum- ing or presented difficulties in data acquisition. Much of the progress that FIA has made over the years is the result of better hardware designs and the practical implementation of chemistry. This conference strives to bring these two important aspects of science together.The WCFIA 92 will focus on how industrial FIA techniques have helped solve real world problems. New hardware- and software-driven applications will be presented. The conference will consist of two and a half days highlighting the follow- ing areas process chemistry; bio- technology; instrument design; new methods; atomic spectroscopy; and electrochemistry.418 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 In addition to the technical sessions the conference offers a unique oppor- tunity for the informal exchange of information and ideas among the che- mists and engineers working on the FIA field. There will also be an instru- ment exhibition. Call for papers Papers and posters should be received by November 15 199 1.Accepted papers will be 20 min in length. It is suggested that 35 mm slides are used for the presentation. Posters should fit on 1 . 2 2 ~ 1.83 m presen- tation boards. Sunday excursion As many airfares are lower for Satur- day arrivals WCFIA 92 is planning an optional group outing for participants and/or families on Sunday January 12 1992. The Scottsdale area is rich in Old West culture and activities. Addi- tional details will be sent with registra- tion confirmation. Registration Registration includes the conference dinner and a conference memento. The deadline for pre-registration is December 3 1991 conference fees before this date are regular US$200; student US$ 100. On-site registration fee is US$250.Registration can be done by fax (206) 685-3478 or by telephone (206) 543-1635. A confirmation package will be sent by December 15 1991. Registration cancellations will be as- sessed a US$50 administration fee. Accommodation Embassy Suites Resort Hotel 5001 N. Scottsdale Road Scottsdale AZ 85250 USA telephone (602) 949-1456. Room rates are US $105- 120 (plus tax). Rates include airport shuttle complimentary break fast buffet and a two-hour nightly cocktail reception. Recreation facili- ties include tennis golf exercise rooms pool and spa. Shopping malls are abundant in the neighbourhood and well-known ‘Old Scottsdale’ is just a walk down Scottsdale Road. Please make reservations directly with the hotel. For further information please contact the organizing committee either Pro- fessor G.D. Christian University of Washington Seattle WA; Professor G. E. Pacy Miami University Oxford OH; or Professor J. RGiiEka Univer- sity of Washington Seattle WA USA. Third International Conference on Plasma Source Mass Spectrometry September 13- 18 1992 University of Durham Durham UK The conference is the third biennial meeting on plasma source mass spec- trometry to be held at the University of Durham. Papers are invited on all aspects of plasma source mass spectro- metry including both inductively coupled plasma MS and glow dis- charge MS. The scientific programme will consist of invited and open lec- tures discussion sessions and poster presentations. A full programme of social events will also take place. The conference is sponsored by VG Elemental and organized in con- junction with the University of Durham. For further information contact Dr. J. G. Holland Department of Geological Sciences The University Science Lab- oratories South Road Durham DH1 3LE UK.

ISSN:0267-9477    

DOI:10.1039/JA9910600417

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

418 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 Courses Analytical Science and the Environ- ment October-December 199 1 Imperial College of Science Technology and Medicine Royal Holloway and Bed- ford New College and the Open Univer- sity A series of related courses on the practical evaluation and monitoring of trace elements in the environment these courses will be of particular interest to consultants researchers and laboratory managers with responsi- bility for solving environmental prob- lems. Problem Solving in Environmental Sciences sampling analytical tech- niques and data interpretation. Dr. M. Rarnsey and Dr. P. J. Potts. October 22-24 199 1. Inductively Coupled Plasma Atomic Emission Spectrometry sample prepa- ration techniques analysis and inter- pretation.Dr. J. N. Walsh and Dr. I. Jarvis. November 5-7 1991. Inductively Coupled Plasma Mass Spectrometry a powerful analytical tool for the environmental scientist. Dr. K. E. Jarvis and Dr. J. G. Williams. November 19-2 1 199 1 . X-ray fluorescence analytical prac- tice in the fields (f environmental industrial and research sciences. Dr. P. J. Potts and Dr. P. C. Webb. December 3-5 199 1 . Activation Spectrometry the role of neutron activation and gamma ray spectrometry in environmental analy- sis. Dr. S. J. Parry. December 10- 12,199 1. For details of these courses please contact Pamela Manser Continuing Education Centre Imperial College Room 5 5 8 Sherfield Building London SW7 2AZ UK. Telephone +44 (0)71 225 8666/7; fax +44 (0)71 225 8668. Atomic Absorption Short Course December 16-20 199 1 Department of Chemistry Loughborough University of Technology Loughborough Leicest- ershire UK An intensive introductory course on the theory practice and application of atomic absorption spectrometry. Suit- able for the beginner but also relevant to those in more senior positions who need to broaden their knowledge on this subject.Lectures will be given by University staff and by experts from the public sector industrial labora- tories and instrument companies. The course is supported by most of the leading manufacturers and the practi- cal sessions are conducted on modern commercial instruments with guid- ance from manufacturers representa- t ives . Course fee E650 (VAT not appli- cable) including accommodation and meals in a University hall of residence.For further information please con- tact the Course Secretary Mrs. s. J. Maddison Department of Chemistry Loughborough University of Techno- logy Loughborough Leicestershire LEI 1 3TU UK. Inductively Coupled Plasma Mass Spectrometry Short Course May 18-22 1992 Department of Chemistry Lough borough University of Technology Loughborough Leicest- ershire UK This is a new addition to the well- established series of courses on analyt- ical chemistry run by the Lough- borough analytical group. The course aims to provide a comprehensiveJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 419 Sixth Biennial National Atomic Spectroscopy Symposium will be held at PoIytechnic South West PIymouth UK 22-24 July 1992 The symposium will provide a forum where interesting and useful applications of atomic spectros- copy can be reported and discussed.In addition to plenary invited and submitted lectures a particu- lar feature of the meeting will be the presentation of posters. There will also be an exhibition and a social programme for delegates and their guests. Scientific programme will include Plenary Lecturers- M.W. Blades (Vancouver BC Canada) BY. L’vov (Leningrad USSR) J.W. McLaren (Ottawa Ontario Canada) K. Niemax (Dortmund Germany) B.L. Sharp (Lmghborough UK) Invited Lecturers- J. S. Crighton (Sunbury-on-Thames UK) H. Falk (Kleve Germany) S.J. Hill (Plymouth UK) D. Littlejohn (Glasgow UK) C. McLwd (Shefield UK) G. Schlemmer (oberlingen Germany) P. Stockwell (Sevenoaks UK) J.F.Tyson (Amherst MA USA) J.G. Williams (Egham UK) A.M. Ure (Glusgow UK) This meeting is organized by the Atomic Spectroscopy Group Analytical Division of The Royal Society of Chemistry. Further information can be obtained from the Chairman of the organizing committee Dr S. J. Hill Department of Environmental Sciences Polytechnic South West Drake Circus Plymouth Devon PL4 SAA UK.420 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 introduction to ICP-MS and will cover the following topics fundamentals of ICP-MS; instrument design; sample introduction; optimization; analytical methodology; isotopic analysis and isotope ratio determinations; and ap- plications which include geochemical environmental nuclear and biological. The course will be delivered through a combination of lectures tutorials and practicals.The support of the leading manufacturers is also antici- pated and their staff will be present to assist with the practicals and to pro- vide information on the latest com- mercial developments. Accommoda- tion will be in Burleigh Court the University’s new Short Course Centre which provides facilities equivalent to those of a mid-range hotel. For further information please contact the Course Secretary Mrs. S. J. Mad- dison Department of Chemistry Loughborough University of Techno- logy Loughborough Leicestershire LE11 3TU UK. Journal Style Update Spelling of Sulfur The new (1990) edition of IUPAC’s ‘Nomenclature of Inorganic Chemis- try’ contains a table of IUPAC-ap- proved names ‘for use in the English language’. These include ‘caesium’ ‘aluminium’ and ‘sulfur’ (spellings as given here). There is an increasing use of the ‘f’ rather than the ‘ph’ spelling for sulfur in English publications in particular the English language ver- sions of IS0 and European standards and those British Standards that implement IS0 standards verbatim. Furthermore there is no good etymo- logical basis for preferring the ‘ph’ spelling. In view of these considera- tions the Royal Society of Chemistry’s Nomenclature Committee has recently recommended that the RSC change to using the ‘f’ spelling in all publications. This recommendation will be imple- mented for the RSC’s primary journals in 1992. Alan McNaught Manager RSC Journals Thomas Graham House Science Park Cambridge UK

ISSN:0267-9477    

DOI:10.1039/JA9910600418

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

420 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 Future Issues will Include- Direct Determination of Copper and Iron in Edible Oils Using Flow Injec- tion Flame Atomic Absorption Spec- trometry-V. Carbonell A. R. Maurc A. Salvador and Miguel de la Guardia Interference of Copper Silver and Gold in the Determination of Selenium by Hydride Generation Atomic Fluo- rescence Spectrometry an Approach to the Studies of Transition Metal Inter- ferences-Alessandro D’Ulivo Leo- nardo Lampugani and Roberto Zamboni Accuracy of Multi-element Analysis of Human Tissue Obtained at Autopsy Using Inductively Coupled Plasma Mass Spectrometry-Thomas D. B. Lyon G. S. Fell Keith McKay and Roger D. Scott Study of Internal Standardization for Analysis of Powdered Samples Using a Theta Pinch Discharge-Zuwei Wang and Alexander Scheeline Influence of Solvent Physical Prop- erties on Drop Size Distribution Transport and Sensitivity in Flame Atomic Absorption Spectrometry With Pneumatic Nebulization-Juan Mora Vicente Hernandis and Antonio Canals Electrothermal Vaporization Sample Introduction System for the Analysis of Pelletized Solids by Inductively Coupled Plasma .4tomic Emission Spectrometry-V.Karanassios J. M. Ren and Eric D. Salin Laser Ablation in a Liquid Medium as a Technique for Solid Sampling- Yasuo Iida Akira Tsuge Yoshinori Uwamino Hisashi Morikawa and Toshio Ishizuka Preliminary Investigations of a Helium Alternating Current Plasma for the Determination of Metals by Atomic Emission Spectrometry-Luis A. Colon and Eugene F. Barry Atomic Spectrometry Update The Update in the October issue is- Inorganic Mass Spectrometry and X- ray Fluorescence-Jeffrey R. Bacon Andrew T. Ellis and John G. Williams

ISSN:0267-9477    

DOI:10.1039/JA9910600420

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 42 1 Comparison of Normal and Low-flow Torches for Inductively Coupled Plasma Mass Spectrometry Using Optimized Operating Conditions E. Hywel Evans* and Les Ebdon Plymouth Analytical Chemistry Research Unit Department of Environmental Sciences Polytechnic South West Drake Circus Plymouth Devon PL4 8AA UK Simplex optimization has been used in order to optimize inductively coupled plasma (ICP) operating conditions for ICP mass spectrometry (namely nebulizer auxiliary and coolant gas flows and forward power) using a standard and a low-flow torch. The signal intensity for In+ at m/z 115 was used as the criterion of merit. Analyte signals were lower by a factor of approximately 3 for the low-flow torch compared with the standard torch.The Ba2+:Ba+ ratio was greater by a factor of 7 for the low-flow compared with the standard torch while the BaO+:Ba+ ratios were low for both torches. The ArO+:ln+ and ArN+:ln+ ratios were higher for the low-flow torch and the ArAr+:ln+ ratios were low for both torches. A relatively flat mass response curve was obtained using the low-flow torch indicating that mass discrimination effects were less pronounced for ions extracted from the plasma formed using this torch. Plasma stability was better with the low-flow torch compared with the standard torch when introducing volatile organic solvents. Keywords Inductively coupled plasma mass spectrometry; simplex optimization; low-flow torch; organic solvent Reports of optimization studies for inductively coupled plasma mass spectrometry (ICP-MS)*-6 have mainly de- tailed the effects of individual operating parameters on analytical performance.Whereas optimization studies for ICP atomic emission spectrometry (ICP-AES) generally use signal-to-background ratio or signal-to-noise ratio as the criterion of merit owing to the relatively large varia- tions in continuum background optimization studies for ICP-MS generally use maximum signal as the criterion of merit because of the low continuum background. More important from the point of view of ICP-MS is the need to optimize the instrument for maximum analyte re- sponse while at the same time minimizing potential interferences such as doubly charged and polyatomic ions. Several workers have optimized plasma operating con- ditions and ion lens voltages for the two main commer- cially available systems namely the Sciex Elan (Sciex Thornhill Ontario Canada)'~~.~ and the VG PlasmaQuad (VG Elemental Winsford Cheshire UK).2,3*6 These work- ers optimized the systems for maximum signal using univariate optimization techniques and subsequently chose operating conditions which gave large analyte sig- nals but also minimal signals due to doubly-charged and polyatomic ions.In general they concluded that suitable compromise operating conditions could be found for different elements with widely differing masses ioniza- tion potentials and chemistries and that these conditions yielded tolerably low levels of doubly charged and oxide ions. However it is possible that other workers may find completely contrary results since it has been our experi- ence that there is a great deal of variability in the levels of polyatomic ions from day-to-day with the same instru- ment let alone between different instruments.Such varia- bility may depend to a great extent on the condition of the sampling and skimmer cones which gradually deter- iorate with time. The trends observed for the two instru- ments were broadly similar although differences have been noted in the behaviour of doubly charged ions,3 probably owing to important differences in the design of the load coil interface and ion lenses which have a great influence on the ion energies of extracted ions and their subsequent transmission into the quadrupole analyser. All workers identified the most important para- * Present address University of Cincinnati Department of Chemistry Mail Location 1 72 Cincinnati OH 4522 1-0 172 USA.meters to be nebulizer gas flow forward power and sampling depth. The optimization studies mentioned above have been applied to ICP-MS systems operating with standard compo- nents and the preferred optimization technique has been to perform a series of univariate searches. However a more rigorous optimization regime is necessary for instrumental systems that have operating parameters that are interdepen- dent variables. Recently Schmit and Chauvette5 and Evans and Caruso6 have demonstrated the applicability of a multivariate simplex optimization technique for tuning of the ion lens voltages. Since the operating variables are known to interact univariate methods alone are unsuitable for system optimization.Therefore a multivariate optimi- zation technique such as simplex optimization is necessary in order to locate the true optimum. Low-flow torches have been shown to allow more stable plasma operation for ICP-AES.' It has been observed in this laboratory8 that stable operation of the plasma is more difficult for ICP-MS compared with ICP-AES on the introduction of an organic solvent probably because of the perturbing effect of the interface which is in contact with the plasma in the former instrument. There- fore a low-flow torch may have certain advantages over the standard torch in ICP-MS for the introduction of organic solvents. Gordon et aL9 have optimized a water cooled low-flow torch for ICP-MS using a univariate optimization tech- nique and arrived at the optimum operating conditions of plasma gas 2.1 1 min-l; neublizer gas 0.20 1 min-l; and forward power 1100 W.Using this torch they observed analyte signals comparable with those obtained with the standard torch. Ross et a1.lo have studied a 9 mm torch and found it to give similar sensitivities and doubly charged ion and oxide ratios to a conventional plasma. However in the last two s t u d i e ~ ~ ? ~ ~ the operating condi- tions were optimized using univariate approaches. Simplex optimization has so far not been applied to ICP-MS for the optimization of the plasma operating conditions but has been shown to offer particular advantages for ICP-AES.11-13 In the present work plasma operating conditions using both a standard torch and a low-flow torch have been optimized by using simplex optimization and the two torches subsequently evaluated with regard to plasma stability for the introduction of volatile organic sol- vents.422 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL.6 Experimental Instrumentation All experiments were performed using an inductively coupled plasma mass spectrometer (VG PlasmaQuad 2). Torch dimensions are given in Table 1. The low-flow torch differed from the standard torch in that the spacing between the intermediate and outer tubes and the internal diameter of the injector tube were smaller in the former. Addition- ally the inlet tubes for the auxiliary (intermediate) and coolant (outer) gases were constricted in the low-flow torch thereby increasing the velocity of these gases through the intermediate and outer tubes respectively. A standard concentric nebulizer was used in conjunction with the low- flow torch and a V-groove nebulizer (Ebdon nebulizer PS Analytical Sevenoaks Kent UK) with the standard torch.Simplex Optimization Parameters The parameters which were optimized are listed in Table 2 with the ranges over which the optimization experiments were conducted. The sampling depth was not included because adjustment of this parameter caused arcing be- tween the torch box and sampling cone probably owing to a loose radiofrequency connection. The sampling depth was maintained at 11 mm and the spray chamber at 2 "C. Simplex optimization experiments were performed using a software package developed previously14 and run on a microcomputer (Apple IIe Apple Computer Cupertino CA USA).The algorithm used was based on that of Yarbro and Derning,ls and initially covered the whole of the factor space then contracting in step size by 50% for each contraction as the optimum was approached. The optimum was deemed to have been reached when the relative standard deviation of the response factors for the vertices retained in the simplex was within the medium term precision of the technique which was given as 5% for this experiment. The signal intensity for In+ in area counts s-l at m/z 1 15 was taken as the criterion of merit. Whenever operating conditions were altered the ion lenses (extraction collec- tor L1 L2 L3 and L4) and the pole-bias were re-adjusted manually by the operator in order to obtain the maxi- mum signal.Additionally the position of the torch in the horizontal and vertical planes was re-adjusted in the same way so as to obtain a maximum signal. This was particularly critical for the low-flow torch since the small internal diameter of the injector meant that accurate alignment with the sampler orifice was important in order to achieve maximum analyte signal. After each optimization was completed univariate searches were performed for each parameter in turn while holding the others at the optimum established by using the simplex procedure. Mass Spectrometer Operating Conditions The mass spectrometer was operated in survey scanning mode throughout. Data acquisition parameters are listed in Table 3.Reagents and Standards A multi-element standard solution of Be Co In Ba and Pb 100 ng ml-l was prepared by dilution of a 10 pg ml-l multi-element stock solution using 2% v/v nitric acid (Aristar BDH Chemicals Poole Dorset UK) in distilled de-ionized water. All multi-element stock solutions were made up using single element standard solutions (Spectro- SOL BDH Chemicals). Results and Discussion Optimization experiments were completed in 25-30 steps. The only problem encountered was that caused by extreme sets of operating conditions at the boundary limits which made tuning of the ion lenses difficult. Table 4 shows the optimum conditions established for the standard and low-flow torches. Univariate searches at the established optimum conditions for analyte signal Ba2+:Ba+ ratio BaO+:Ba+ ratio ArO+ ArN+ and ArAr+ are shown in Figs.1 - 1 5. Despite the fact that the optimization was performed using llsIn+ as the criterion of merit it was considered useful to compare the effects of operating conditions on the criteria mentioned above so that a valid comparison between the two torches could be made with respect to polyatomic and doubly charged ions. On completion of the optimization the simplex proce- dure retained the five vertices which gave the best response factors each vertex consisting of a set of operating conditions. The vertical arrows on Figs. 1 4 10 and 13 Table 1 Dimensions of the standard and low-flow torches in mm Torch dimension Standard torch Low-flow torch Injector tube i.d. 1.6 1 .o Intermediate tube 0.d.15.6 16.6 Outer tube 0.d. 20.4 20.4 Outer tube i.d. 18.0 18.0 Configuration factor 0.77 0.8 1 Gas inlets. i.d. 6 2 Table 2 Boundary limits of parameters studied during the simplex optimization Range Table 3 Data acquisition parameters used in survey scanning mode Value Parameter Mass range mlz Number of channels Number of scan sweeps Dwell timelps Time per scads Number of scans 8.0-215.5 2048 100 320 65.5 I Table 4 Optimum operating conditions established for the stan- dard and low-flow torches Optimum conditions Parameter Standard torch Low-flow torch Nebulizer gasll min-' 0.200-1.250 0-0.800 Auxiliary gasll min-' 0-2.5 0-2.0 Coolant gasll min-I 11-18 6-10 Forward powerlW 900- 1 800 500-900 Parameter Standard torch Low-flow torch Nebulizer gad1 min-I 0.842 0.670 Auxiliary gad1 min-I 0.8 1.6 Coolant gad1 min-l 11.5 6.8 Forward power/W 1583 865JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL.6 423 indicate the optimum condition for each of the operating conditions which was obtained in each instance by averag- ing the values for each of the parameters in the five vertices retained by the simplex procedure. The error bars represent the range of values obtained for each operating condition. The trends shown in the graphs for the analyte signal were repeatable from day-to-day and the optimum did not exhibit significant variation over a period of several months. The absolute magnitude of the signals varied with time and the polyatomic ion to indium ratios also varied considerably.However the general trends remained rela- tively similar and were sufficiently dissimilar for the two torches to warrant comparison. The effects of the different operating parameters on the criteria mentioned above are discussed below. Effect of Operating Parameters Nebulizer gas The effect of nebulizer gas flow on analyte signal for the elements Be Co In Ba and Pb using the isotopes at mlz 9 59 115 138 and 208 respectively is shown in Fig. l(a) for the standard torch and Fig. l(b) for the low-flow torch. It should be remembered that the optimization was per- formed using the In+ response as the criterion of merit hence the vertical arrows indicate the optimum conditions for this element only. The simplex procedure located the optimum successfully for both torches.However for the standard torch [Fig. l(a)] Be+ and Co+ signals peaked at higher nebulizer gas flow rates than In+ and Ba+ and Pb+ signals peaked at slightly lower flow rates the trend being that the lower the mass the higher the nebulizer flow rate 100000 (a) t 80000 60000 40000 - 20000 4- C 3 8 ( D o I I I Ag P\ 25000 20000 15000 10000 5000 n 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 Nebulizer gas flow/l min-’ Fig. 1 Effect of nebulizer gas flow on signals for A 9Be+; B 59C0+; C llsIn+- D 138Ba+; and E 208Pb+ using (a) the standard and (b) the low-flow torch that was required for maximum signal. Gray and co- workers2J6 have shown that the plasma potential and ion energies for elements of different mass are dependent on the nebulizer gas flow and forward power at least in the VG PlasmaQuad instrument for which plasma potentials be- tween + 5 and + 20 V are common.A consequence of this is that certain sets of operating conditions may result in ion energies which vary across the mass range making it difficult to optimize the ion lenses in order to achieve uniform response for elements of different mass. This may be the cause of the trends observed and shown in Fig. l(a) since the ion optics were optimized for In+ only. These results differ from those of Gray and Williams2 who found that one nebulizer gas flow was optimum for elements of different mass. One explanation for this may be that they performed experiments at 1300 W forward power whereas this work was performed at 1583 W forward power which was found to be the optimum.Douglas and French” have suggested that ion energies vary considerably more than those reported by Gray and Williams,2 owing to measure- ment of the ion energies after the ion optics which act as a filter for ions of the same energy. For the low-flow torch with the exception of Be all elements exhibited maximum signals at more or less the same nebulizer gas flow [Fig. l(b)J. Gordon et aL9 have postulated that the plasma potential is greater in plasmas operated at lower than normal flows with a consequent increase in ion energies. However as long as the spread in ion energies for elements of different masses is small then one set of ion lens conditions such as those for In+ should be optimum for all ions. This seems to be true for the low- flow plasma studied in this work with the exception of Be.The major effect of a high plasma potential is to increase the amount of doubly charged i ~ n s . ~ J ~ This effect was observed for the low-flow torch studied in this work the Ba2+:Ba+ ratio showing a peak that coincided with the peaks in analyte signals and having the high value of approximately 0.5 at its maximum [Fig. 2(b)]. During operation of the low-flow torch what appeared to be a secondary discharge or boundary layer was visible at the sampler orifice. The large amounts of doubly charged ions formed might explain why the peak of the Ba2+:Ba+ ratio closely matched that for the analyte signal. For the 0.6 0.4 0.2 + (D 0 m +- 0 standard torch the Ba2+:Ba+ ratio was much (a) 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 Nebulizer gas flow/l min-’ Fig.2 Effect of nebulizer gas flow on the ratios for A Ba2+:Ba+; and B BaO+:Ba+ using (a) the standard and (b) low-flow torch424 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 lower at the optimum nebulizer gas flow [Fig. 2(a)] in comparison with the low-flow torch but increased as gas flow increased. These results are consistent with those obtained by other workers2v3 using a PlasmaQuad instru- ment with an asymmetrically grounded load coil. Gray et a1.16 have shown that as nebulizer gas flow increases so does the plasma potential resulting in an increase in the amount of doubly charged ions a decrease in ArO+:Co+ and ArAr+:Co+ ratios and a slight decrease in CeO+. For the Elan instrument with a centre tapped load coil the Ba2+:Ba+ ratio decreases with nebulizer gas flow.' The behaviour is different in this instrument because the plasma potential is relatively low,'* i.e.+0.5 to -3.5 V and less dependent on operating conditions. For both torches the BaO+:Ba+ ratios were low at optimum nebulizer gas flows [Fig. 2(a) and (b)] and therefore would not give rise to serious potential interfer- ences. The BaO+:Ba+ ratio increased slightly at high gas flow for the standard torch [Fig. 2(a)] in agreement with Gray and Williams,2 and the ratio showed a small peak at 0.75 1 min-l for the low-flow torch [Fig. 2(b)] which closely follows the trend observed for analyte signal suggesting that the observed trend was influenced by factors such as analyte or O+ transport into the plasma.The effect of nebulizer gas flow on ArO+ ArN+ and ArAr+ is shown in Fig. 3. For the standard torch the trends exhibited in Fig. 3(a) agree with those reported by Gray and Williams,* and each show a minimum at the optimum nebulizer gas flow though the response for ArAr+ was much lower in this study. In contrast for the low-flow torch the ArN+ and ArO+ signals peaked at nebulizer gas flows which were the same as and 0.01 1 min-l higher respectively than the optimum for In+ signal [Fig. 3(b)]. This difference 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 Nebulizer gas flow/l rnin-' Fig. 3 Effect of nebulizer gas flow on the signals for A ArO+; B ArN+; and C ArAr+ using (a) the standard and (b) the low-flow torch is significant because the data were acquired within the same experiment for all masses.It is likely that the presence of the O+ and N+ precursors influenced the formation of the polyatomic species to the greatest extent their concen- tration in the plasma being determined by the nebulizer gas flow. However Douglas and French17 have calculated that for low-flow argon plasmas a greater proportion of the plasma gas will be sampled through the sampler orifice possibly leading to greater entrainment of atmospheric gases which also influence the formation of ArO+ and ArN+. Whatever the situation more work is necessary in order to determine the mechanisms of formation of these species in a low-flow low-power plasma with a high plasma potential. The low-flow torch gave rise to a smaller signal for ArAr+ in comparison with the standard torch (Fig.3) though the difference was not great. The low-flow torch gave rise to a smaller signal for ArAr+ in comparison with the standard torch (Fig. 3) though the difference was not great. Forward power The effect of forward power on the analyte signal is shown in Fig. 4 for both torches. With regard to the standard torch [Fig. 4(a)] the simplex procedure has successfully located the optimum forward power for maximum In+ signal. However the maximum signals for Be+ and Co+ were at lower power while those for Ba+ and Pb+ were at higher power. As observed for nebulizer gas flow the optima were mass dependent although in this instance the order was reversed i. e. higher masses required higher power for maximum signal. A correlation between power and first 50000 40000 30000 20000 10000 B I 1 I m m C 22 P .- a 80000 60000 40000 20000 0 400 800 1200 1600 2000 Forward power/W Fig.4 Effect of forward power on signals for A 9Be+; B 59C0+; C llsIn+. D 138Ba+; and E 208Pb+ using (a) the standard and (b) low- flow torchJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 42 5 Table 5 Masses of the major isotopes first ionization potentials ( I ) and apparent optimum powers (Popl) for the elements studied Isotope I,/V PO,l/W 9Be 9.32 1300 5 9 c 0 7.86 1350 ll51n 5.79 1583 13*Ba 5.21 >1800 zo8Pb 7.42 >1800 ionization potential cannot be made i.e. those elements with highest first ionization potentials would require high- est power whereas this was not true (Table 5). A disparity in ion energies for elements of different mass may again explain the apparent differences in optima as discussed for nebulizer gas flow since the ion optics were optimized for In+ only.Gray et a l l 6 found that plasma potential and hence ion energies increase as nebulizer gas flow is increased but decrease as power is increased. Bearing this in mind the trends in mass dependent optima for nebulizer gas flow and power support each other Taking Pb as an example for one particular nebulizer gas flow or forward power Pb+ ions will have a greater energy than In+ ions due to the mass dependent acquisition of kinetic energy in the expansion region. Hence Pb+ ions with energies required for maximum transmission through ion optics optimized for In+ will be most prevalent at a lower nebulizer gas flow or a higher power than is optimal for In+.Such an effect was observed in this work however since no measurements or ion energy were made such an explana- tion remains tentative. For the low-flow torch maximum signal was not obtained for any of the elements even at the highest power studied [Fig. 4(b)]. The simplex procedure located the ‘optimum’ power for the In+ signal at a lower value than would be regarded as optimum i.e. the optimization failed. This was because at a power greater than 1000 W the torch started to melt requiring a false low response to be input to the computer whenever such a condition arose. This is the normally accepted procedure for the type of algorithm used but it can lead to poor results when the optimum is close to or beyond one of the boundary conditions. This had the effect of causing the simplex to locate an ‘optimum’ at a lower power.However the trends exhibited show a similar pattern for all elements indicating that the discrepancy in ion energies was less pronounced with the low-flow torch compared with the standard torch. The increase in analyte response with increasing power is probably due to a corresponding increase in ionization temperature. For the standard torch the Ba2+:Ba+ ratio decreased with increasing power to less than 0.1 at the optimum [Fig. 5(a)] in agreement with the results of Long and Brown,3 and possibly owing to a corresponding decrease in plasma potential. The BaO+:Ba+ ratio was less than 0.01 at all powers studied. For the low-flow torch the Ba*+:Ba+ ratio trend exhibited different behaviour showing a maximum at 825 W [Fig.5(b)]. The subsequent decrease in the ratio above 825 W could have been due to a decrease in plasma potential though this seems unlikely. As mentioned already a discharge was visible in the sampler orifice during oper- ation and this may well have had an effect. Gordon et aL9 observed Ce2+:Ce+ ratios of up to 1.0 and a much broader peak profile between 900 and 1400 W using a water cooled low-flow torch though it was operated at much lower gas flows and was different in design. Evidently it is desirable to operate this particular torch at the maximum power possible in order to reduce the Ba2+:Ba+ ratio while at the 1 .o 0.8 0.6 0.4 0.2 + l-0 0 rn i o 4d X (a) A 400 800 1200 1600 2000 Forward power/W Fig.5 Effect of forward power on the ratios for A Ba2+:Ba+; and B BaO+:Ba+ using (a) the standard and (b) the low-flow torch same time improving the analyte signals. The BaO+:Ba+ ratio was of the order of 0.0 1 between 800 and 1000 W [Fig. 5(b)] which was the analytically useful power range. The ArO+ and ArN+ signals exhibited contrasting behav- iour for the two torches (Fig. 6). Whereas for the standard 40000 20000 r UJ v) 4d = o s Forward powerIW Fig. 6 Effect of forward power on the signals for A A&+; B ArN+; and C ArAr+ using (a) the standard and (b) the low-flow torch426 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 0.8 0.6 0.4 torch the signals for these species decreased with increasing forward power [Fig. 6(a)] for the low-flow torch the signals decreased to a minimum at 700 W increased to maxima at 950 and 900 W respectively then decreased again [Fig.6(b)]. In the latter instance i.e. the low-flow torch the initial decrease in polyatomic ions may have been due to a reduction in the entrainment of atmospheric gases as the plasma increased in size with increasing power. Subse- quently O+ and N+ precursors from the nebulizer gas may have predominated and the polyatomic ions increased as ionization temperature increased with power until the point at which other factors such as ion energy or decomposition had a greater influence. The ArAr+ signal varied very little for both torches over the power ranges studied. - - - Sampling depth The sampling depth parameter was not included in the simplex optimization but was held constant at 11.0 mm.However univariate searches were undertaken in an effort to ascertain whether this parameter had a significant effect on the criteria already mentioned. Sampling depth is defined as the distance between the tip of the sampling cone and the foremost coil of the load coil. For the standard torch analyte signals decreased as the sampling distance was increased [Fig. 7(a)] which would be expected as ions were sampled from successively cooler regions of the plasma where ion populations were lower. There was comparatively little change in analyte signals as the sampling distance of the low-flow torch was increased [Fig. 7(b)]. This could have been owing to the secondary discharge in the sampling orifice which probably influenced the degree of ionization of the elements to the greatest 50000 40000 30000 20000 1oooc v) v) t4 ; c (D m 1.m 2 120000 & 100000 .- v) 80000 60000 40000 20000 n ( b ) B 1 8 9 10 11 12 13 Sampling cone-load coil distance/mm Fig. 7 Effect of sampling depth on signals for A 9Be+; B s9C0+; C IlsIn+; D 13*Ba+; and E 2osPb+ using (a) the standard and (b) the low-flow torch 1 .o (a) 0.2 1 B % - n~ 0 I I 8 9 10 11 12 13 Sampling cone-load coil distance/mm Fig. 8 Effect of sampling depth on the ratios for A Ba2+:Ba+; and B BaO+:Ba+ using (a) the standard and (b) the low-flow torch extent rather than the sampling distance. However the discharge did change in intensity as the sampling distance was altered becoming more intense at greater distances. Similarly very little change was observed in the Ba2+:Ba+ and BaO+:Ba+ ratios for either torch (Fig.8) although a steady increase in the Ba2+:Ba+ ratio was observed using the low-flow torch as the distance between the sampling cone and the load coil was increased [Fig. 8(b)]. This was probably linked to the discharge in the sampler orifice which increased in intensity as the sampling position moved further away from the load coil. A gradual increase in the signals for ArO+ ArN+ and ArAr+ was observed as sampling distance from the load coil 40000 20000 - v) v) C 3 c 8 0 m 40000 1 C 0 v) .- 20000 (a) C A Y Y 8 9 10 11 12 13 Sampling cone-load coil distance/mm Fig. 9 Effect of sampling depth on the signals for A ArO+; B ArN+; C and ArAr+ using (a) the standard and (b) the low-flow torchJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL.6 427 increased for the standard torch [Fig. 9(a)] probably because ions were sampled from a cooler region of the plasma. The trends exhibited by these ions when using the low-flow torch contrasted greatly with each other [Fig. 9(b)]. The signal for ArO+ decreased that for ArN+ increased slightly and that for ArAr+ remained constant. The con- trasting trends for ArO+ and ArN+ suggest that these ions may have been formed with precursors from different sources in the low-flow plasma either from the nebulizer gas or from entrained atmospheric gases. Auxiliary gas The simplex optimization successfully located the optimum gas flows for both torches. The trends in analyte signals observed for the standard torch [Fig.10(a)] agree with the results of Long and Brown3 who observed an identical pattern albeit at lower gas flows. For the low-flow torch auxiliary gas flow had little effect on analyte signals [Fig. 1 O(b)]. Likewise Ba2+:Ba+ and BaO+:Ba+ ratios were relatively unaffected (Fig. 11) for both torches. The ArO+ and ArN+ signals exhibited similar behaviour for the standard torch [Fig. 12(a)] although contrasting this with the behaviour for the low-flow torch [Fig. 12(b)] suggests again that these ions were formed with precursors from different sources with this torch. For both torches the optimum gas flows determined for In coincided with signals close to the minima observed for these ions. The ArAr+ signal varied very little over the ranges studied for either torch (Fig.12). 100000 80000 60000 40000 7 20000 fn 3 4- 8 0 l i (a) B 25000 20000 1 = 1 (11111 0 0.5 1.0 1.5 2.0 2.5 3.0 Auxiliary gas flow/l min-’ Fig. 10 Effect of auxiliary gas flow on signals for A 9Be+; B 59C0+; C IlsIn+; D 138Ba+; and E ***Pb+ using (a) the standard and (b) the low-flow torch 0.4 o . 6 ~ + 0.2 - 0 0.5 1.0 1.5 2.0 2.5 3.0 Auxiliary gas flow/l min-’ Fig. 11 Effect of auxiliary gas flow on the ratios for A BaZ+ Ba+; and B BaO+:Ba+ using (a) the standard and (b) the low-flow torch 60000 40000 20000 fn fn 3 4- C I 8 0 60000 m 1. C 0 m .- 40000 20000 0 (a) ( b ) I B 7 3 3 Y * .c Y U 1l u 0.5 1.0 1.5 2.0 2.5 3.0 Auxiliary gas flow/l min-’ Fig. 12 Effect of auxiliary gas flow on the signals for A ArO+; B ArN+; and C ArAr+ using (a) the standard and (b) the low-flow torch Coolant gas The simplex optimization located the ‘optimum’ coolant gas flow to be close to the lower boundary limit for both torches (Fig.13). Evidently the true optima were below the boundary limits for coolant gas flow at 1 1 and 6 1 min-l for the standard and low-flow torches respectively. The torches could not be operated below these flows because of the danger of melting. Analyte signals varied in a similar428 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 :TA B manner for both torches i.e. decreasing as coolant gas flow increased. However a coolant gas flow of 10 1 min-' would be necessary for the low-flow torch if it was operated at the maximum power of 1000 W. The BaO+:Ba+ ratios remained relatively constant throughout the range of coolant gas flow studied for both torches (Fig. 14).The Ba2+:Ba+ ratios exhibited contrasting t 50000 40000 30000 20000 B " ( a ) m - Is v) .- 30000 t ' ' 20000 10000 0 1 - \ 5 10 15 20 Coolant gas fIow/I min-' Fig. 13 Effect of coolant gas flow on signals for A 9Be+ B 59C0+; C I151n+; D 138Ba+; and E 2osPb+ using (a) the standard and (b) the low-flow torch 0.8 0 2 0.6 .- 4- 0.4 0.2 0 5 10 15 20 Coolant gas fIow/I min-' Fig. 14 Effect of coolant gas flow on the ratios for A BaZ+:Ba+; and B BaO+:Ba+ using (a) the standard and (b) the low-flow torch behaviour for the two torches with respect to coolant gas flow (Fig. 14). It is difficult to assess the influence of this parameter on the formation of Ba2+ ions in the plasma.Increasing the coolant gas flow caused an increase in the intensity of the discharge in the sampler orifice using the low-flow torch which probably contributed to the increase in the Ba2+:Ba+ ratio. The signals for ArO+ ArN+ and ArAr+ showed very little change with respect to coolant gas flow for the standard torch [Fig. 15(a)]. However once again the ArO+ and ArN+ signals exhibited dissimilar trends for the low-flow torch [Fig. 15(b)]. This lends further strength to the argument that these species were formed with precursors from different sources in the low-flow plasma. More significantly such species were more prevalent in the low-flow plasma and were more sensitive to coolant gas flow than the standard torch. 40000 20000 - I cn c +I Z o (II m 22 (II C Is v) 40000 .- 20000 0 A- B $5 Coolant gas flow/! min-' Fig.15 Effect of coolant gas flow on the signals for A ArO+; B ArN+; and C ArAr+ using (a) the standard and (b) the low-flow torch Semi-quantitative Calibration Fig. 1 6 shows two semi-quantitative calibration graphs constructed when using the low-flow torch. Fig. 16(a) illustrates the effect of including Ba in the calibration. In m X 1191 1 (a) X I "---' 0 1 41.50 83.00 124.5 166.0 207.5 m/z Fig. 16 Semi-quantitative calibration graphs calculated using the low-flow torch with (a) 138Ba+ included; and (b) 138Ba+ excludedJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY. SEPTEMBER 199 1 VOL. 6 429 this instance the signal for I3*Ba+ was degraded because of the propensity for Ba2+ ions to form when this torch is used and the calibration was rendered useless.However when Ba was excluded a useful calibration was obtained [Fig. 16(b)]. Because of this effect it may be necessary to perform a separate calibration using elements with low first ioniza- tion potentials if such elements are to be determined semi- quantitatively. Another interesting property of the low-flow torch was the relatively high sensitivity achieved for 9Be+. A relatively flat mass response curve was obtained using the low-flow torch compared with that typically obtained with a stan- dard torch. The relatively high signals obtained for 9Be+ and 59C0+ were observed throughout the experiment although there was considerable variation in relative signal intensities for different operating conditions.It is suspected that the existence of the secondary discharge in the sampler orifice may have played an important role in that it increased the ion energies of the elements thereby reducing space charge effects in the ion beam resulting in less defocusing of the light elements. Effect of Organic Solvents Several organic solvents of differing volatility were intro- duced into the plasmas formed with the standard and low- flow torches and their effects on plasma stability and reflected power noted. The torches were operated using the conditions shown in Table 6. It was necessary to introduce oxygen into the nebulizer gas in order to prevent carbon deposition on the cones the amount depending on the solvent used. Also the sample uptake rate was reduced considerably for the more volatile solvents namely acetone cyclohexane and hexane al- though in general a greater sample uptake rate could be tolerated by the low-flow torch.The performance of the two torches with respect to reflected power and plasma stability is shown in Table 7. It is evident from Table 7 that the low-flow torch was much more tolerant of organic solvents especially the more volatile solvents than the standard torch. This may be an Table 6 Operating conditions for the low-flow and standard torches for organic solvent introduction Parameter Standard torch Low-flow torch Ar nebulizer gad1 min-' O2 nebulizer gad1 min-l Auxiliary gad1 min-l Coolant gad1 min-I Forward power/W Sampling depth/mm Spray chamber temperature/"C Sample uptake rate/ml min-' 0.802 1.3 0.025-0.071 15 1800 10.5 -2 0.12-1.46 0.655 0.025-0.1 15 1 .o 10 1000 10.5 - 2 0.12-1.46 Table 7 Reflected power and plasma stability (S stable; U unstable; and VU very unstable) compared for the low-flow and standard torches during organic solvent introduction Standard torch Low-flow torch Reflected Plasma Reflected Plasma Solvent power/W stability power/W stability Propan-2-01 45 S 10 S Ethanol 42 S 10 S Methanol 60 S 12 S Acetone 80 vu 25 S Cyclohexane 65 vu 20 S Hexane 67 vu 45 U Table 8 Figures of merit for the standard and low-flow torches operated at optimum conditions Figure of Standard Low-flow merit torch torch 'I5In+ signal/area counts s-I 47 591 17 508 Ba2+:Ba+ 0.078 0.510 0.008 BaO+:Ba+ ArO + In + 0.19 1.12 ArN+:In+ 0.12 0.27 ArAr+:Tn+ 0.001 0.003 0.020 advantage for the analysis of organic solvents and coupled high-performance liquid chromatography-ICP-MS studies where the mobile phase may be volatile. Conclusions A comparison of various figures of merit can be made for the two torches operating at conditions found to be optimum for maximum In+ signal by reference to Table 8.In general signals for a number of elements covering the mass range being studied were lower with the low-flow torch compared with the standard torch although considerable variation in the magnitude of signals for the low mass elements Be and Co was noted for the low-flow torch. The Ba2+:Ba+ ratio was much greater and was influenced differently by operating parameters for the low-flow com- pared with the standard torch probably because of a greater plasma potential in the low-flow plasma.The BaO+:Ba+ ratios were low for both torches with no significant differences with respect to operating parameters. The ArO+:In+ and ArN+:In+ ratios were higher for the low-flow compared with the standard torch probably owing to the greater air entrainment and results suggest that the ArO+ and ArN+ species were formed with precursors from different sources in the low-flow plasma and to a lesser extent in the plasma formed using the standard torch. The ArAr+:In+ ratio was lower for the low-flow compared with the standard torch. A relatively flat mass response curve was achieved using the low-flow torch and the plasma formed with this torch was much more stable for the introduction of organic solvents which may be an advantage in some applications involving volatile solvents.The support of E.H.E. by the Science and Engineering Research Council and ICI Materials Research Centre under the Co-operative Award in Science and Engineering (CASE) scheme is gratefully acknowledged. References Vaughan M. A. and Horlick G. Appl. Spectrosc. 1986 40 434. Gray A. L. and Williams J. G. J. Anal. At. Spectrom. 1987 2 599. Long S. E. and Brown R. M. Analyst 1986 111 901. Vaughan M. A. Horlick G. and Tan S. H. J. Anal. At. Spectrom. 1987 2 765. Schmit J.-P. and Chauvette A. J. Anal. At. Spectrum. 1989 4 755. Evans E. H. and Caruso J. A. presented at the 1991 Pittsburgh Conference Chicago USA 3rd-8th March 1991 paper No. 109 1. Ng R. C. Kaiser H. and Meddings B. Spectrochim. Acta Part B 1985 40 63.430 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 8 Evans E. H. Ebdon L. and Barnett N. W. presented at the 1989 European Conference on Plasma Spectrochemistry Reutte Austria 8th-14th January 1989 paper No. P2-44. 9 Gordon J. S. van der Plas P. S. C. and de Galan L. Anal. Chem. 1988 60 375. 10 Ross B. S. Chambers D. M. Vickers G. H. Yang P. and Hieftje G. M. J. Anal. At. Spectrom. 1990 5 351. 11 Ebdon L. Evans E. H. and Barnett N. W. J. Anal. At. Spectrom. 1989 4 505. 12 Ebdon L. Cave M. R. and Mowthorpe D. J. Anal. Chim. Acta. 1980 115 179. 13 Cave M. R. Kaminaris D. M. Ebdon L. and Mowthorpe D. J. Anal. Pruc. 1981 18 12. 14 Norman P. Ph.D. Thesis Plymouth Polytechnic Council for National Academic Awards 1987. 15 Yarbro L. A. and Deming S. N. Anal. Chim. Acta 1974,73 391. 16 Gray A. L. Houk R. S. and Williams J . G. J. Anal. At. Spectrom. 1987 2 13. 17 Douglas D. J. and French J. B. J. Anal. At. Spectrom. 1988 3,743. 18 Houk R. S. Schoer J. K. and Crain J. S. J. Anal. At. Spectrom. 1987 2 283. Paper 1/01 842F Received March 15th 1991 Accepted April 19th I991

ISSN:0267-9477    

DOI:10.1039/JA9910600421

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 Analytical Performance Evaluation of a 40.68 MHz Inductively Coupled Plasma Mass Spectrometer 43 1 Chang J. Park and Kwang W. Lee Inorganic Analytical Laboratory Korea Standards Research Institute P. 0. Box 3 Taedok Science Town Taejon Korea The instrumentation of a new 40.68 MHz inductively coupled plasma (ICP) mass spectrometer is described. An optimization study has been carried out for the instrument. Of the many operating parameters the carrier argon flow rate is the most sensitive and the optimum carrier argon flow rate is found to be much lower than the literature values for a 27.12 MHz ICP mass spectrometer. The analytical performance of the instrument i.e. the detection limits background mass spectrum and formation of oxides and doubly charged ions is also evaluated.Keywords Inductively coupled plasma mass spectrometry; 40.68 MHz plasma; optimization and analytical performance; detection limits; background spectrum Since the first commercially available inductively coupled plasma mass spectrometer was introduced at the 1983 Pittsburgh Conference inductively coupled plasma mass spectrometry (ICP-MS) has received a lot of interest in many analytical fields such as geochemical e~ploration,~-~ environ- mental pr~tection,~ biomedical research5 and quality control in nuclear fuel6 and materials7 industries. In Korea ICP-MS is being used increasingly because of the important advan- tages of simple spectra high sensitivity and isotope abun- dance information. During 1989- 1990 about ten ICP-MS instruments were installed in Korean national research institutes and quality control laboratories.It is however reported in Korea that the down time of the instruments is much higher than that of other well-established analytical instruments such as ICP emission spectrometers and atomic absorption spectrometers probably because ICP-MS is a relatively young technique and most operators do not fully understand the basic principles.8 The Korea Standards Research Institute as a national centre for measurement of standards and also as an educational centre for analytical instrumentation developed an ICP-MS instrument to be used for the certification of reference materials and fundamental studies of ICP-MS. This paper presents the instrumentation and evaluation of the analytical performance of a laboratory-built ICP-MS system. The evaluated analytical performance includes the back- ground mass spectrum doubly charged and oxide ion formation detection limits and isotope ratio measurements of the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) isotopic standards.Experimental Reagents All laboratory ware was washed with de-ionized water from a Milli-Q system (Millipore Bedford MA USA). Standard solutions were prepared using sub-boiling quartz-distilled water. All chemicals employed were of analytical-reagent grade. Instrumentation The ICP source consists of an r.f. generator impedance matching unit gas panel load coil torch and sample introduction unit as shown in Fig.1. The plasma is generated by a 40.68 MHz r.f. generator (Model ICP-l6L RF Plasma Products Marlton NJ USA) which uses a field effect transistor (FET) instead of the conventional power tube. It is therefore very compact (482.6 mm rack mount) and requires no warm-up time. For sample introduction a Meinhard concentric nebulizer (TR-30-K3) and Scott-type spray chamber are used and a peristaltic pump (Minipuls 3 Gilson Medical Electronics Middleton WI USA) is em- ployed to control the sample uptake rate. The carrier argon gas flow is precisely controlled by a mass flow controller (Vacuum General San Diego CA USA). The torch box housing a standard short torch (Superior ICP Denver CO USA) nebulizer spray chamber and impedance matching unit sit on a laboratory-built xyz translator. Typical ICP- MS operating conditions are given in Table 1.A schematic diagram of the interface and quadrupole mass spectrometer is shown in Fig. 2. The interface is pumped by a 7.5 I s-' rotary pump (SD450 Varian Lexington MA USA). The sampler and skimmer orifices are 1 and 0.7 mm in diameter respectively and the distance between the two orifices is 8 mm. Both aluminium and nickel orifices were successfully employed in this instrument but throughout this work the aluminium orifices were used. The orifices are mounted on water-cooled flanges without the use of bolts they are simply screwed into the flanges. With this mount- / * Copper . braided I wire Tesla P coil cooling water pressure Gas 23-96 PF R.f. Spray chamber II Nebulizer Mass flow controller 11 40.68 MHz r.f. generator cooling water - R.f.inter-lock Gas panel Fig. 1 ICP generation system432 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 Einzel lens Fig. 2 Schematic diagram of interface and quadrupole mass spectrometer .Il....m......._r_..rrl..LI.I...m_..._ Fig. 3 Calculated ion trajectories in the electrostatic lens system Table 1 Optimized ICP-MS operating conditions Forward power Reflected power Coolant flow rate Auxiliary flow rate Carrier gas flow rate Nebulizer pressure Sample uptake rate Sampling depth Interface pressure Quadrupole chamber pressure 1.2 kW <3 w 12 1 min-' 0.4 1 min-' 0.37 1 min-I 2.1 x los Pa 0.8 ml min-I 10 mm 2.1 x lo2 Pa 1.1 x Pa ing a vacuum leak which was often observed for the bolt- fastened orifices did not occur for the 6 months the spectrometer was in operation.The vacuum chamber which houses an electrostatic lens assembly and a quadru- pole mass filter is isolated from the interface by a laboratory-built gate valve (36 mm thick) when the plasma is not sampled. Between the skimmer cone and gate valve is a cylindrical lens biased to about - 200 V to attract positive ions towards the electrostatic lens assembly. The vacuum chamber is separated into two parts by the exit plate (hole of 4 mm diameter) of the Bessel box. The first chamber houses the front part of the electrostatic lens assembly and is pumped by a 1200 1 s-I diffusion pump (VHS-4 Varian). The second chamber contains the rear part of the lens assembly and a quadrupole mass filter and is pumped by a 285 1 s-' diffusion pump (HS-2 Varian).The chamber and vacuum line pressures are monitored by two vacuum controllers (Varian 843 and Balzers TPG 300) and vacuum valves are automatically controlled by a labora- tory-built valve controller. The ion optics in this instrument were designed by utilizing a computer program (SIMION Idaho National Engineering Laboratory Idaho Falls ID USA). Fig. 3 shows the calculated ion trajectories assuming a 10 eV ion energy. The quadrupole mass filter (SX300 VG Quadru- poles Winsford Cheshire UK) is composed of four (12 mm i.d. 230 mm long) molybdenum rods and has a mass range of 1-300 u. The quadrupole mass control is accom- plished by the 10 V analogue output of a 12 bit digital to analogue converter (DAC) card (WB-AVO-B2 Omega Stamford CT USA).Pulse counting mode is used for signal detection. Negative pulses are generated when ions hit an electron multiplier (CEM4870 Galileo Electro-Optics Sturbridge MA USA). They are then converted into transistor-transistor logic (TTL) pulses through a charge sensitive preamplifier-discriminator (A 1 1 1 AMPTEK Bedford MA USA). The discriminator threshold was set to approximately 1 x lo6 electrons in order to remove theJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 433 quadrupole r.f. noise at the highest mass detected (238U160+). The TTL pulses are counted displayed and manipulated by a multichannel scaler card (ACE-MCS EG&G ORTEC Oak Ridge TN USA) plugged into an IBM PC-AT computer. In mass scanning each DAC output change advances one channel in the multichannel scaler and thus for the 12 bit DAC 13.65 channels on average are allocated to a particular mass.Results and Discussion Background Mass Spectra The background mass spectrum observed when distilled de-ionized water is nebulized into the plasma is shown in Fig. 4(a) and was obtained by accumulating 50 scans from m/z= 10-85. Five hundred and twenty channels were assigned to cover the 76 masses with a dwell time per channel of 2 ms and hence a complete spectrum was obtained in 52 s. The integrated count rate over 100 ms in each channel was converted into a count rate per second. The detector bias potential was substantially reduced so that the maximum peak count rate [Fig. 4(a)] could not exceed 1 x lo6 counts.The background spectrum in Fig. 4(a) shows typical major peaks at mlz values of 16 (O+) 17 (OH+) 18 (OH2+) 32 (02+) 40 (Ar+) and 4 1 (ArH+). Among the major peaks the doubly charged argon ion (Ar2+) is unusual indicating that this instrument has a serious discharge at the sampler orifice. The secondary discharge was also confirmed by visual inspection of the sampler orifice. The discharge at the sampler orifice did not enlarge the orifice diameter but produced widely eroded areas around the orifice. The aluminium sampler orifice was less affected by erosion than the nickel orifice with no noticeable change in sensitivity. Minor background peaks at full sensitivity from 20 to 30 and from mlz 43 to 85 were separately obtained with an optimum bias potential appiied to the detector and are shown in Fig.4(b). It can be seen that the intensity of the A1 background peak at m/z = 27 from the orifice material is about 1600 counts s-l which is equivalent to a standard signal for approximately 2 ppb. Fig. 4(b) also shows that the distilled de-ionized water used in this work is contami- nated with Ca Sc and Zn. In general however background ion-free regions of the spectrum are fairly clean with a noise level of about 10 counts s-l. Optimization Horlick et aL9 published the effect of the operating parameters for the Sciex Elan 250 ICP-MS instrument. Long and Brownlo subsequently reported their work on the optimization of the operating parameters for a VG Plasma- Quad ICP-MS instrument. Both groups concluded that the most sensitive parameters were the aerosol carrier gas flow rate and r.f.forward power. In this work optimization of three operating parameters for the 40.68 MHz ICP-MS instrument was studied. The three parameters were carrier gas flow rate r.f. forward power and sampling depth. In Figs. 5-10 the data points plotted for each mass are the means of 60 channel values which are obtained by the accumulation of 500 sweeps in the single ion monitoring mode with a dwell time per channel of 2 ms. Typical relative standard deviation (RSD) values for the ions of interest are given in Table 2. Fig. 5 shows the effect of the carrier gas flow rate for six different ions at a 1.2 kW r.f. forward power and 10 mm sampling depth. The response curves show that the opti- mum carrier gas flow rate is between 0.35 and 0.4 1 rnin-l and varies little for different ions.The optimum carrier gas flow rate of this instrument is found to be much lower than those reported for ICP-MS instruments with 27.12 kW r.f. 1 .o 0.9 0.8 v) 0.7 3 0.6 2 0.5 g 0.4 = 0.3 0.2 0.1 0 v) 4- 8 IL) \ U > .- al + 10 30 50 70 90 40 30 v) 3 0 4- 2 20 1 + > v) al C .- 4- - 10 20 30 40 60 mlz 80 Fig. 4 background peaks from mlz 20 to 30 and 43 to 85 (a) Background mass spectrum from mlz 1 to 85; (b) minor ~ ~~ Table 2 Typical RSD values of 60 data points with an integration time of 1 s per data point when nebulizing 100 ppb solutions Ion Mass number RSD (%) ArO+ cu+ Ar + &+ Ba+ La+ Ce+ Pb+ U+ 56 63 80 107 138 139 140 208 238 3.3 0.9 0.7 0.7 0.9 0.8 0.9 0.8 0.7 generators (0.69,' 0.6-0.8,ll and 1.0612 1 min-l) which implies that the plasma backpressure of the 40.68 MHz ICP is lower than that of the 27.12 MHz ICP owing to the reduced skin depth. Because of the low optimun? carrier gas flow rate the TR-30-C1 Meinhard nebulizer initially employed was replaced by a TR-30-K3 nebulizer which was specially designed for low (0.7 1 min-') flow.The two types of Meinhard nebulizer gave almost the same optimum carrier gas flow rates and sensitivities. The effect of r.f. forward power is presented in Fig. 6 for five analytes with the carrier gas flow rate and sampling depth held constant at 0.37 1 min-l and 10 mm respec-434 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 626 0.3 0.34 0.38 0.42 0.46 Carrier gas flow rate/t min-' Fig.5 Effect of carrier gas flow rate on 100 ppb analyte signals 1 I I 1 I J 0.9 1.0 1.1 1.2 1.3 1.4 1.5 R.f. forward power/kW Fig. 6 Effect of r.f. power on 100 ppb analyte signals tively. The optimum r.f. forward power of 1.2-1.35 kW is slightly different for different analytes. Comparison of Figs. 5 and 6 indicates that the effect of r.f. forward power is not as great as that of the carrier gas flow rate. Since the lowest sampling depth (separation distance between sampler orifice and the grounded end of the load coil) is 10 mm for this instrument the effect of varying the sampling depth from 10 to 19 mm with 1.5 mm intervals was studied. The results are presented in Fig. 7 for three analytes argon oxide and an argon dimer. For Figs. 7-10 the values of r.f.power carrier gas flow rate and sampling depth listed in Table 1 were used unless otherwise stated. Fig. 7 shows that the analyte and argon oxide signals decrease continuously as the sampling depth increases while the argon dimer signal increases. This could indicate that the zone at which the argon dimer ions form is further along in the ICP than that at which analyte and argon oxide ions form. The effect of sample uptake rate was also studied. However little variation was observed in the analyte signals as the sample solution uptake rate was varied from 0.8 to 1.5 ml min-'. Formation of Oxides and Doubly Charged Ions Vickers et al.13 compared the analytical characteristics of a 27.12 MHz with those of a 40.68 MHz ICP-MS instrument. They found that interference effects were independent of frequency but that the formation of oxides and doubly charged ions was affected by a more significant orifice- linked discharge with the 40.68 MHz ICP.Since the 160 A 7 120 La Ba 8 10 12 14 16 18 20 Sampling depth/mm Fig. 7 Effect of sampling depth on 100 ppb of analyte ArO+ and AT2+ signals instrument employed in this work used a 40.68 MHz generator with its load coil grounded at the end near the sampler orifice the orifice-linked discharge gave a large number of doubly charged ions (e.g. Ba2+:Ba+=2.2). Wilson et a1.I' reported that the orifice-linked discharge was drastically reduced by running a short strap between the end of the load coil and the sampler orifice flange. Thus the same connection was adopted in this instrument (Fig.l) which reduced the Ba2+:Ba+ ratio to 0.3. Abdallah et al.14 compared the temperatures of the 5 and 40 MHz ICPs and found that excitation and ionization temperatures of the 40 MHz ICP were lower than those of the 5 MHz ICP. Barnes and Schlei~her~~ applied a com- puter model of the ICP discharge to the calculation of the possible effects of frequency on the discharge properties. The computations predicted that in the higher frequency discharge the maximum temperature was lower than in the low frequency discharge. Thus the ICP mass spectrometer equipped with the 40.68 MHz ICP source is expected to give higher oxide signals compared with the conventional 27.12 MHz instrument. Since oxides and doubly charged ions can present a spectral interference problem the ratios of oxides and doubly charged ions to singly ionized species (MO+:M+ and M2+:M+) are often reported in the literature as an impor- tant rating of analytical performance.Thus in this work the effect of carrier gas flow rate and sampling depth on MO+:M+ and M2+:M+ ratios was investigated for five elements whose oxide bond strengths and second ioniza- tions potentials are given in Table 3. Fig. 8 shows the MO+:M+ ratios increasing slowly as the carrier gas flow rate is increased. The primary reason for this trend is that for all five elements the MO+ counts showed a steady increase as the carrier gas flow rate increased while the M+ counts showed maxima at opti- mum flow rates. The above trend is not consistent with that reported by Long and Brownlo except for Ba.They observed minimum MO+:M+ ratios at near optimum flow rates for Pb Cs and Sm. For the M2+:M+ ratios M2+ counts in addition to M+ counts were observed to increase owing to the formation of a central channel in the plasma as the carrier gas flow rate is increased to an optimum however the M2+ counts tend to increase more rapidly up to the maximum. When the flow rate was further increased both counts dropped owing to the decreased residence time in the plasma. Thus M2+:M+ ratios plotted in Fig. 9 show an increasing rise with increasing carrier gas flow rate. Figs. 8 and 9 generally show that elements of higher oxide bond strength give higher MO+:M+ ratios and that those ofJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 43 5 Table 3 Oxide bond strength and second ionization potential of the elements of interest Oxide bond strength/ Second ionization potential/ Element kJ mol-l eV Ba 563 La - Ce 795 Pb 378 U 76 1 10.00 11.06 10.85 15.03 - 0.28 0.32 0.36 0.4 Carrier gas flow rate/! min-' Fig.8 MO+:M+ ratios versus carrier gas flow rate 0 1 -5 0.28 0.32 0.36 0.4 Carrier gas flow rate/I min-' Fig. 9 M2+:M+ ratios versus carrier gas flow rate lower second ionization potential give higher M2+:M+ ratios as expected. Comparison of the ratios at an optimum carrier gas flow rate with the literature suggests that this instrument should generate slightly higher oxide and doubly charged ion levels. The higher M2+:M+ ratios are believed to be due to the enhanced secondary discharge at the orifice from the 40.68 MHz ICP and the higher MO+:M+ ratios due to the lower temperature of the higher frequency ICP.Lim et all8 measured the potential of a supersonic jet expanding into the interface at various plasma sampling positions. They found that the jet poten- tial increased suddenly at a sampling depth of about 32 mm. Further increase in the sampling depth gradually reduced the jet potential. Their work suggests that the secondary discharge in the spectrometer should be some- how affected by the sampling depth. Thus the effect of sampling depth on the M2+:M+ and MO+:M+ ratios was studied with this instrument. The results are plotted in Fig. I I x - x I -1 .o -5.0 + PbO' P b' 8 10 12 14 16 18 20 Sampling de pt h/m m Fig. 10 MO+:M+ and M2+:M+ ratios versus sampling depth 10 and show an obvious trend i.e.MO+:M+ ratios fall as the sampling depth is increased while M2+:M+ ratios rise. The M2+ counts show a maximum at a sampling depth of about 12 mm which is 2 mm longer than the lowest sampling depth at which M+ counts show a maximum. However M+ counts of the three elements in Fig. 10 were observed to drop more rapidly than M2+ counts as the sampling depth was increased further. It is obvious that M+ M2+ and MO+ counts decrease owing to dilution as the sampling depth is increased. However there seems to be a mechanism which affects the order of the rate of decrease (ie. MO+ counts drop most rapidly and M2+ counts least rapidly). A strong discharge between the sampler orifice and the plasma which was not visible at the normal sampling depth was observed visually with this instrument when the sampling depth was very high (about 30 mm).Thus the secondary discharge at the orifice can get stronger as the sampling depth is increased from 10 to 19 mm which could account for the rising M2+:M+ ratios and falling MO+:M+ ratios in Fig. 10. Detection Limits The operating conditions listed in Table 1 were obtained through an optimization study and used in determining detection limits and isotope ratios. In order to estimate detection limits the background noise was obtained by aspirating distilled de-ionized water at each mass and the signal counts from nebulizing 100 ppb standard solutions. Both noise and signal counts were acquired by accumulat- ing 100 sweeps of 60 channels in the single-ion mode with a dwell time of 10 ms per channel.Detection limits were determined by calculating the concentration of the element which would give a signal three times the standard deviation (SD) of the background noise. Detection limits of six elements together with the SD of the background noise and 100 ppb standard signals are presented in Table 4 and show that this instrument can offer almost the same levels of detection limits as the commercially available instruments. Isotope Ratio Measurements One of the advantages of ICP-MS is the rapid and convenient determination of isotope ratios with moderate precision (0.1- 1 Yo) and high sensitivity. The rapid determi- nation of isotope ratios enables analysts to use the isotope dilution method which is one of the few absolute methods offering high accuracy.l 9 The isotope ratio measurement capability of this instru- ment was evaluated by analysing four NIST isotopic436 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 1991 VOL. 6 Table 4 Detection limits for 100 ng ml-1 solutions Element Isotope c u 63 Ag 107 Ba 138 La 139 Pb 208 U 238 SD of background noisel counts s-l 8.2 7.8 8.5 9.9 19.1 7.4 Signall counts s-I 59 000 44 000 5 5 000 65 000 130 000 126 000 Detection limit/ ng ml-' 0.04 0.05 0.05 0.05 0.05 0.02 ~~ Table 5 Measured ratios of isotopic NIST SRMs Isotope ratio Run No. 1 2 3 4 5 Mean rt SD RSD (O/O) NIST certified value Error (O/O) NIST SRM 951 ( l0B IlB) 0.253 0.258 0.253 0.257 0.246 0.253 4 0.005 1.9 0.247 + 2.4 NIST SRM 976 2.194 2.167 2.155 2.189 2.139 2.169 k 0.020 1 .o (63Cu:Tu) 2.244 -3.3 NIST SRM 978a ( lo7.4g:Io9Ag) 1.04 1 1.034 1.045 1.047 1.023 0.9 1.038 k 0.009 1.076 - 3.5 Table 6 Measured isotope abundances of NIST SRM 981 Lead Metal Natural Isotope abundance (O/O) Run No.1 2 3 4 5 Mean k SD RSD (Yo) NIST certified value Error (Yo) 204Pb 1.32 1.38 1.42 1.53 1.45 1.42 k 0.08 5.5 1.4245 -0.3 206Pb 24.24 24.05 24.02 23.95 24.00 24.05 ? 0.1 1 0.5 24.1447 -0.4 207Pb 22.34 22.68 22.39 22.54 22.15 0.9 22.42 +- 0.2 22.0827 + 1.5 2osPb 52.10 5 1.89 52.17 5 1.98 52.40 52.1 1 +- 0.20 0.4 52.348 1 -0.5 standards. In Table 5 the measured isotope ratios of boron (NIST SRM Boric Acid) copper (NIST SRM 976 Copper Metal) and silver (NIST SRM 978a Silver Nitrate) are presented. The error between the determined ratios and the NIST certified data is less than 3.5% and RSD values for five measurements are also less than 1 O/o except for boron.In Table 6 the measured isotope abundances of a lead isotopic standard (NIST SRM 981 Lead Metal Natural) are shown. Table 6 shows the excellent agreement with the certified data and the good reproducibility except for the minor isotope 204Pb. The concentrations of the NIST isotopic standards were 200 ppb for Cu Ag and Pb and 500 ppb for B. For the data acquisition only minimum mass ranges were scanned 200 times with a dwell time of 10 ms per channel. Isotope ratios were then obtained by integrating the peak areas of the isotopes. Conclusion The new ICP-MS system built in this laboratory has almost the same detection power but gives slightly higher levels of doubly charged and oxide ions compared with the commer- cial instruments.Since a 40.68 MHz ICP source is employed in the system the optimum carrier gas flow rate is substantially lower than in the systems which utilize a 27.12 MHz source. The system shows great promise as a tool for quantitative work using isotope dilution and also for fundamental studies of ICP-MS. References 1 Date A. R. and Hutchinson D. Spectrochim. Acta Part B 1986 41 175. 2 Hall G. E. M. Park C. J. and Pelchat J. C. J. Anal. At. Spectrom. 1987 2 189. 3 Lichte F. E. Meier A. L. and Crock J. G. Anal. Chem. 1987 59 1150. 4 Boomer D. W. and Powell M. J.,Anal. Chem. 1987,59,2810. 5 Delves H. T. and Campbell M. J. J. Anal. At. Spectrom. 1988 3 343. 6 Beck G. L. and Farmer 0. T. J. Anal. At. Spectrom. 1988,3 771.JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY SEPTEMBER 199 1 VOL. 6 437 7 Stotesbury S. J. Pickering J . M. and Grifferty M. A. J. Anal. At. Spectrom. 1989 4 457. 8 Park C. J. and Lee K. W. paper presented at the 5th Annual Meeting of the Korean Society of Analytical Science Seoul 1990 paper No. PL3. 9 Horlick G. Tan S. H. Vaughan M. A. and Rose C. A. Spectrochim. Acta Part B 1985 40 1555. 10 Long S. E. and Brown R. M. Analyst 1986 111 901. 11 Wilson D. A. Vickers G. H. Hieftje G. M. and Zander A. T. Spectrochim. Acta Part B 1987 42 29. 12 Tan S. H. and Horlick G. Appl. Spectrosc. 1986 40 445. 13 Vickers G. H. Wilson D. A. and Hieftje G. M. J. ilnal. At. Spectrom. 1989 4 749. 14 Abdallah M. H. Diemiaszonek R. Jarosz J. Mermet. J.-M. Robin J. and Trassy C. Anal. Chim. Acta 1976 84 271. 15 Barnes R. M. and Schleicher R. G. Spectrochim. Acta Part B 1975 30 109. 16 Gray A. L. and Williams J. G. J. Anal. At. Spectrom. 1987 2 81. 17 Vaughan M. A. and Horlick G. Appl. Spectrosc. 1986 40 434. 18 Lim H. B. Houk R. S. and Crain J. S. Spectrochim. Acta Part B 1989 44 989. 19 Heumann K. G. TrAC. TrendsAnal. Chem. (Pers. Ed.) 1982 1 357. Paper I /006 I30 Received February 11 th I991 Accepted May I6th I991

ISSN:0267-9477    

DOI:10.1039/JA9910600431

出版商:RSC    

年代:1991

数据来源: RSC