摘要:

1988 Winter Conference On Plasma Spectrochemis try San Diego, California, USA January 5 9 , 1988 The 1988 Winter Conference on Plasma Spectrochemistry, fifth in a series of biennial meetings sponsored by the ICP Information Newsletter, will feature developments in plasma spectrochemical analysis by inductively coupled plasma (ICP), d.c. plasma (DCP), microwave plasma (MIP) and glow and hollow-cathode discharge (GDL, HCL) sources. The meeting will convene Monday, January 4 to Saturday, January 9,1988 at the San Diego Princess resort and convention centre in San Diego. Expert short courses at introductory and advanced levels and an exhibition of spectroscopic instrumentation also will be included. ~ Programme and Objectives Symposia organised and chaired by recognised experts will include the following topics: (1) Sample introduction and transport phenomena; (2) Listrumentation and automation, including on-line analysis and remote systems; (3) Excitation mechanisms and plasma characteristics; (4) Interferometry; ( 5 ) Atomic fluorescence; (6) Glow and hollow-cathode discharges; (7) Flow injection analysis; (8) Chromatography and plasma detectors; (9) Plasma source mass spectrometry; (10) Industrial applications of ICP mass spectrometry; and (11) Sample preparation and pre-concentration techniques.Six plenary and 15 invited lectures will be presented. Three afternoon poster sessions will feature applications, automation and new instrumentation. Four panel discussions will address critical development areas. Plenary, invited and submitted papers will be published as the official conference proceedings following the meeting after peer review in Journal of Analytical Atomic Spectrometry , September 1988 issue.Instrument Exhibition A three day exhibition of spectroscopic instrumentation and chemicals , electronics, glassware, publications and software supporting plasma spectroscopy will complement the scheduled sessions. Expert Short Courses Introductory and advanced four-hour short courses will be offered January 2-3 and 9,1988. Designed to provide background and intensive training in popular topics of plasma spectrochemistry, these will cover analytical applications, instrumentation, samples introduction and various techniques (e.g., plasma diagnostics, scientific writing, chemical and physical pre-concentration and applications of isotope dilution and tracers).Registration The conference registration fee includes a copy of the conference proceedings, abstracts, a tee-shirt and conference dinner. The pre-registration fee is $275 until October 16, 1987, after which time it will be $375. On-site registration will be $400. Discounts are provided for students, and no registration fee is required for spouses. Short-course pre-registration fee $75 for each four-hour short course, after October 16 this will be $100. Further details on all aspects of the Conference can be obtained from: Dr. Ramon M. Barnes Department of Chemistry, GRC Towers, University of Massachusetts, Amherst, MA 01003-0035, USA (413) 545-2294Journal of Analytical Atomic Spectrometry (Including Atomic Spectrometry Updates - Formerly ARAAS) JAAS Editorial Board* Chairman: L. C.Ebdon (Plymouth, UK) J. Brew (London, UK) M. S. Cresser (Aberdeen, UK) D. L. Miles (Wallingford, UK) B. L. Sharp (Aberdeen, UK) M. Thompson (London, UK) A. M. Ure (Aberdeen, UK) *The JAAS Editorial Board reports t o the Analytical Editorial Board, Chairman J. D. R. Thomas (Cardiff, UK) JAAS Advisory Board F. C. Adams (Antwerp, Belgium) R. M. Barnes (Amherst, MA, USA) L. Bezur (Budapest, Hungary) R. F. Browner (Atlanta, GA, USA) S. Caroli (Rome, Italy) L. de Galan (Delft, The Netherlands) J. B. Dawson (Leeds, UK) K. Dittrich (Leipzig, GDR) W. Frech (Umeii, Sweden) K. Fuwa (Tokyo, Japan) A. L. Gray (Guildford, UK) S. Greenfield (Loughborough, UK) G. M. Hieftje (Bloomington, IN, USA) G.Horlick (Edmonton, Canada) J. J. LaBrecque (Vienna, Austria) 6. V. L'vov (Leningrad, USSR) J. M. Mermet (Villeurbanne, France) Ni Zhe-ming (Beijing, China) N. Omenetto (lspra, Italy) E. PlSko (Bratislava, Czechoslovakia) R. E. Sturgeon (Ottawa, Canada) R. Van Grieken (Antwerp, Belgium) A. Walsh, K. 6. (Victoria, Australia) B. Welz (Uberlingen, FRG) T. S. West (Aberdeen, UK) Atomic Spectrometry Updates Editorial Board Chairman: *M. S. Cresser (Aberdeen, UK) R. M. Barnes (Amherst, MA, USA) N. W. Barnett (Plymouth, UK) *J. Brew (London, U? *A. A. Brown (Cambridge, UK) J. C. Burridge (Aberdeen, UK) J. B. Dawson (Leeds, UK) *L. C. Ebdon (Plymouth, UK) H. J. Ellis (Ross-on-Wye, UK) J. Fijalkowski (Warsaw, Poland) D. J. Halls (Glasgow, UK) S. J. Haswell (London, UK) *D.A. Hickman (London, UK) G. M. Hieftje (Bloornington, IN, USA) S. J. Hill (Plymouth, UK) H. Hughes (Anglesey, UK) P. N. Keliher (Villanova, PA, USA) K. Kitagawa (Nagoya, Japan) *D. Littlejohn (Glasgow, UK) C. W. McLeod (SheHield, UK) K. W. Jackson (Saskatoon, Canada) F. J. M. J. Maessen (Amsterdam, The Nether- lands) *J. Marshall (Middlesbrough, UK) *D. L. Miles (Wallingford, UK) J. M. Mermet (Villeurbanne, France) E. Norval (Pretoria, South Africa) I. Novotny (Brno, Czechoslovakia) P. E. Paus (Oslo, Norway) P. R. Poole (Hamilton, New Zealand) T. C. Rains (Washington, DC, USA) J. M. Rooke (Leeds, UK) G. Rossi (lspra, Italy) I. RubeSka (Prague, Czechoslovakia) W. Slavin (Norwalk, CT, USA) R. Stephens (Halifax, Canada) J. Stupar (Ljubljana, Yugoslavia) A.Taylor (Guildford, UK) M. Thompson (London, UK) J. F. Tyson (Loughborough, UK) *A. M. Ure,jAberdeen, UK) B. Welz (Uberlingen, FRG) J. B. Willis (Victoria, Australia) *B. L. Sharp (Aberdeen, UK) *Members of the ASU Executive Committee Editor, JAAS: Judith Brew The Royal Society of Chemistry, Burlington House, Piccadilly, London WIV OBN, UK. Telephone 01 -734 9864. Telex No. 268001 US Associate Editor, JAAS: Dr. J. M. Harnly US Department of Agriculture, Beltsville Human Nutrition Research Center, BLDG 161, BARC-EAST, Beltsville, MD 20705, USA. Telephone 301-344-2569 Advertisements: Advertisement Department, The Royal Society of Chemistry, Burlington House, Piccadilly, London W1V OBN. Telephone 01-437 8656. Telex No. 268001 Journal ofAnalytical Atomic Spectrometry IJAAS) (ISSN 0267-9477) is published eight times a year by The Royal Society of Chemistry, Burlington House, London WlVOBN, UK.All orders accompanied with payment should be sent directly to The Royal Society of Chemistry, The Distribution Centre, Blackhorse Road, Letchworth, Herts.SG6 lHN, UK. 1987 Annual subscription rate UK f180.00, Rest of World f202.00, USA $356.00. 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 (JAAS), Publications Expediting Inc., 200 Meacharn Avenue, Elmont, NY 11003. Second class postage pending at Jamaica, NY 11431. All other despatches outside the UK by Bulk Airmail within Europe, Accelerated Surface Post outside Europe.PRINTED IN THE UK. @The Royal Society of Chemistry, 1987. 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. Information for Authors Full details of how to submit material for publication in JAASare 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 publi- cation of original research papers, short papers, communications and letters concerned with the development and analytical application of atomic spectrometric techniques.The journal will be published bimonthly, will include com- prehensive reviews of specific topics of interest to practising atomic spectroscopists and will incorporate the literature reviews which were previously published in Annual Reports on Analytical Atomic Spectroscopy (ARAAS). Manuscripts intended for publication must describe original work related to atomic spec- trometric analysis. Papers on all aspects of the subject will be accepted, including fundamental studies, novel instrument developments and practical analytical applications. As well as AAS, AES and AFS, papers will be welcomed on atomic mass spectrometry and X-ray fluoresc- ence/emission spectrometry. Papers describing the measurement of molecular species where these relate to the characterisation of sources normally used for the production of atoms, or are concerned, for example, with indirect methods of analysis, will also be acceptable for publication.Papers describing the development and applications of hybrid techniques (e.g., GC-coupled AAS and HPLC - ICP) will be parti- cularly welcome. Manuscripts on other subjects of direct interest to atomic spectroscopists, including sample preparation and dissolution and analyte preconcentration procedures, as well as the statistical interpretation and use of atomic spectrometric data will also be accept- able for publication. There is no page charge. The following types of papers will be con- sidered. Full papers, describing original work. Short papers. the criteria for originality are the same as for full papers, but short papers generally report less extensive investigations or are of limited breadth of subject matter.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 parti- cular 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 g'uided as to its acceptance or rejection. Papers that are accepted must not be published else- where except by permission. Submission of a manuscript will be regarded as an undertaking that the same material is not being considered for publication by another journal. Manuscripts (three copies typed in double spac- ing) should be addressed to: Judith Brew, Editor, JAAS The Royal Society of Chemistry, Burlington House, Piccadilly, London WIV OBN, UK US Associate Editor, JAAS Dr. J. M. Harnly US Department of Agriculture, Beltsville Human Nutrition Research Center, BLDG 161, BARC-EAST, Beltsville, MD 20705, USA or AH queries relating to the presentation and submission of papers, and any correspondence regarding accepted papers and proofs, should be directed to the Editor or US Editor (addresses as above). Members of the JAASEditorial Board (who may be contacted directly or via the Editorial Office) would welcome comments, suggestions and advice on general policy mat- ters concerning JAAS. Fifty reprints are supplied free of charge.

ISSN:0267-9477    

DOI:10.1039/JA98702FX001

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

JASPE2 2( I ) I-86,1 R-42R (1 987) February 1987 Journal of Analytical Atomic Spectrometry Including Atomic Spectrometry Updates CONTENTS NEWS AND VIEWS 1 1 3 6 8 8 8 11 12 12 EditoriaCLes Ebdon Obituary-John Michael Ottaway Lecture Tour of the Far East-Alan R. Date Conference Reports ASU Highlights-Les Ebdon SAC Gold MedaCAlan L. Gray Conferences and Meetings Course Gordon F. Kirkbright Bursary Papers in Future Issues PAPERS 13 21 27 33 39 45 51 55 59 63 67 73 77 81 83 Langmuir Probe Potential Measurements in the Plasma and their Correlation with Mass Spectral Characteristics in Inductively Coupled Plasma Mass Spectrometry-Alan L. Gray, R. S. Houk, John G. Williams Effect of Torch Size on a 148-MHz Inductively Coupled Plasma-Bryan D. Webb, M. Bonner Denton Studies of a Low-noise Laminar Flow Torch for Inductively Coupled Plasma Atomic Emission Spectrometry.Part 2. Noise Power Studies and Interference Effects-John Davies, Richard D. Snook Self-matrix Effects as a Cause of Calibration Curvature in Inductively Coupled Plasma Atomic Emission Spectrometry-Michael H. Ramsey, Michael Thompson, Stephen J. Walton Direct Atomic Spectrometric Analysis by Slurry Atomisation. Part 1. Optimisation of Whole Coal Analysis by Inductively Coupled Plasma Atomic Emission Spectrometry- Les Ebdon, John R. Wilkinson Investigations of a Reduced Palladium Chemical Modifier for Graphite Furnace Atomic Absorption Spectrometry-Lucinda M. Voth-Beach, Douglas E. Shrader Spray Deposition versus Single-drop Deposition for Calibration of an Electrostatic Accumulation Furnace for Electrothermal Atomisation Atomic Absorption Spec- trometry-Giancarlo Torsi, Francesco Palmisano Atomic Absorption Spectrometric Determination of Lead in Gasolines by Generation of its Covalent HydrideJose Aznarez, Juan Carlos Vidal, Rafael Carnicer Population Distribution of Atomic Uranium in the Afterglow of a Pulsed Hollow-cathode DischargeYves Demers, Jean-Marie Gagne, Piero Pianarosa Laser-excited Atomic Fluorescence Spectrometry as a Practical Analytical Method.Part 2. Evaluation of a Graphite Tube Atomiser for the Determination of Trace Amounts of Indium, Gallium, Aluminium, Vanadium and Iridium by LAFS-Klaus Dittrich, Hans-Joachim Stark Silicate Rock Analysis by Energy-dispersive X-ray Fluorescence Using a Cobalt Anode X-ray Tube. Part 2.Practical Application and Routine Performance in the Determination of Chromium, Vanadium and Barium-Philip J. Potts, Peter C. Webb, John S. Watson, David W. Wright KflIKa Intensity Ratios for Rare Earth Compounds Using Radioisotope Induced X-ray FluorescenceKenneth J. Borowski, Fook S. Tham, lvor L. Preiss SHORT PAPER Determination of Metals in Poly(viny1 chloride) by Atomic Absorption Spectrometry. Part 2. Determination of Lead and Magnesium in Samples of Poly(viny1 chloride) with a High Content of Alkaline Earths-Miguel A. Belarra, Jesus M. Anzano, Felix Gallarta, Juan R. Castillo COMM U NlCATl ON Oxide and Doubly Charged Ion Response of a Commercial Inductively Coupled Plasma Mass Spectrometry Instrument-Alan L. Gray, John G. Williams INSTRUCTIONS TO AUTHORS ATOMIC SPECTROMETRY UPDATE 1R Environmental Analysis-Les Ebdon, Malcolm S.Cresser, Cameron W. McLeod 29R References Typeset and printed by Heffers Printers Ltd, Cambridge, EnglandJASPE2 2( I ) I-86,1 R-42R (1 987) February 1987 Journal of Analytical Atomic Spectrometry Including Atomic Spectrometry Updates CONTENTS NEWS AND VIEWS 1 1 3 6 8 8 8 11 12 12 EditoriaCLes Ebdon Obituary-John Michael Ottaway Lecture Tour of the Far East-Alan R. Date Conference Reports ASU Highlights-Les Ebdon SAC Gold MedaCAlan L. Gray Conferences and Meetings Course Gordon F. Kirkbright Bursary Papers in Future Issues PAPERS 13 21 27 33 39 45 51 55 59 63 67 73 77 81 83 Langmuir Probe Potential Measurements in the Plasma and their Correlation with Mass Spectral Characteristics in Inductively Coupled Plasma Mass Spectrometry-Alan L.Gray, R. S. Houk, John G. Williams Effect of Torch Size on a 148-MHz Inductively Coupled Plasma-Bryan D. Webb, M. Bonner Denton Studies of a Low-noise Laminar Flow Torch for Inductively Coupled Plasma Atomic Emission Spectrometry. Part 2. Noise Power Studies and Interference Effects-John Davies, Richard D. Snook Self-matrix Effects as a Cause of Calibration Curvature in Inductively Coupled Plasma Atomic Emission Spectrometry-Michael H. Ramsey, Michael Thompson, Stephen J. Walton Direct Atomic Spectrometric Analysis by Slurry Atomisation. Part 1. Optimisation of Whole Coal Analysis by Inductively Coupled Plasma Atomic Emission Spectrometry- Les Ebdon, John R. Wilkinson Investigations of a Reduced Palladium Chemical Modifier for Graphite Furnace Atomic Absorption Spectrometry-Lucinda M.Voth-Beach, Douglas E. Shrader Spray Deposition versus Single-drop Deposition for Calibration of an Electrostatic Accumulation Furnace for Electrothermal Atomisation Atomic Absorption Spec- trometry-Giancarlo Torsi, Francesco Palmisano Atomic Absorption Spectrometric Determination of Lead in Gasolines by Generation of its Covalent HydrideJose Aznarez, Juan Carlos Vidal, Rafael Carnicer Population Distribution of Atomic Uranium in the Afterglow of a Pulsed Hollow-cathode DischargeYves Demers, Jean-Marie Gagne, Piero Pianarosa Laser-excited Atomic Fluorescence Spectrometry as a Practical Analytical Method. Part 2. Evaluation of a Graphite Tube Atomiser for the Determination of Trace Amounts of Indium, Gallium, Aluminium, Vanadium and Iridium by LAFS-Klaus Dittrich, Hans-Joachim Stark Silicate Rock Analysis by Energy-dispersive X-ray Fluorescence Using a Cobalt Anode X-ray Tube. Part 2.Practical Application and Routine Performance in the Determination of Chromium, Vanadium and Barium-Philip J. Potts, Peter C. Webb, John S. Watson, David W. Wright KflIKa Intensity Ratios for Rare Earth Compounds Using Radioisotope Induced X-ray FluorescenceKenneth J. Borowski, Fook S. Tham, lvor L. Preiss SHORT PAPER Determination of Metals in Poly(viny1 chloride) by Atomic Absorption Spectrometry. Part 2. Determination of Lead and Magnesium in Samples of Poly(viny1 chloride) with a High Content of Alkaline Earths-Miguel A. Belarra, Jesus M. Anzano, Felix Gallarta, Juan R. Castillo COMM U NlCATl ON Oxide and Doubly Charged Ion Response of a Commercial Inductively Coupled Plasma Mass Spectrometry Instrument-Alan L. Gray, John G. Williams INSTRUCTIONS TO AUTHORS ATOMIC SPECTROMETRY UPDATE 1R Environmental Analysis-Les Ebdon, Malcolm S. Cresser, Cameron W. McLeod 29R References Typeset and printed by Heffers Printers Ltd, Cambridge, England

ISSN:0267-9477    

DOI:10.1039/JA98702BX003

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

42 ASU REFERENCE INDEX VOL. 2 (1987) Xu, Yi., 8711226 Xu, Z . , 871.536, 871937 Xue, H . , 871237 Yakimova, N . M., 871970 Yamada, H., 871367 Yamada, K . , 871582. 8711271 Yamada, M., 8711903 Yamamoto, I.. 871244 Yamamoto, M., 871288, 871 1475, 871C 1623 Yamamoto, Y.. 871288, 871 1439 I 871 1475, 87lC 1623 Yamashita, H.. 871372 Yamazaki. H., 871252 Yamazaki. N., 871478 Yamazaki, S.. 8711692 Yan, D., 8711235 Yan, W. Z . , 8711983 Yanagihara, S . , 8712017 Yang, J . , 871273 Yang, L., 87i1449 Yang. M., 871275. 871530 Yang. M. H., 87/303, 871342 Yang, P.. 87lC1375 Yang, X., 87i265, 8711538. Yang, X. D., 8711890 Yang, Y.. 8711214. 8711538 Yang. Z . , 871532 Yao. J., 871524. 8711228 Yao, I,. , 871608 Yao. S., 871276 Yap, C. T., 8716.50 Yasuda. K., 871367 Y asuda, M I , 87lC 1623 Yasui, A ., 8711990 Yatcs, D. A . , 871C555, 87lC1343, 871C1668, 871C 167 1 871C2044 Yates, D. E., 87/88 Yatsenko, L. F.. 8711481 Ybanez, N., 8711240 Ycah, K. S.. 871919 Yeung. E. S . , 871653 Yi, J . , 8711448 Yngstriim. S . . 871287 Yokoi. S . , 8712017 Yokota, F., 8711440 Yonemoto, T., 871437 Yoo, A., 8711501 Yoo. Y. J., 87lC170 Yoon, R.-H.. 871C1630 Yoshida, H., 8711546, 8711547, 8711954 Yoshida, Z . , 871377 Yoshimura, C . , 8711302 Yoshimura, E., 8711692 Yoshimura, K . , 87180 Yoshino, T., 8711582 Yotsuyanagi, T., 8711579 You. S . , 8711226 You, Y . , 871528 Yu. G. X., 8711983 Yu, H.. 871593 Yu, X. Z.. 8711906 Yuan, Z.-N., 871383 Yudclcvich, I. G., 871936, Yurko. R. J . . 87lC558 Zagatto, E. A. G., 871438 Zailaf, M., 8711534 Zakhariya, A. N., 8711901 Zakrevskaya. L.V . . 8711899 Zakrzcwski, Z., 87171 Zalts, A., 87152 Zandcr. A. T., 871123. 871666 Zander. U . , 87lC1000 Zaray, G., 871C1365 871 1482 Zaruba, K., 871C1866 Zauke, G. P., 8711064 Zawadzka, T., 8711315 Zeeman, P. B., 87165 Zclentsova, L. V., 8711482 Zendehnam, A., 871C193 Zeng, X. J.. 8711978, Zhan, G., 87024, 871337, Zhang, C. S.. 8711981 Zhang, €4. U., 8712098 Zhang, J . , 871939 Zhang, J . M., 8711883 Zhang, L.. 871492 Zhang, L. X., 8711981 Zhang, P., 871241 Zhang, Q., 871930 Zhang, S.. 8 7 / 3 3 , 871362, Zhang, W.. 87182 Zhang, X . , 871502 Zhang, Y., 871502, 871526 Zhang, Z . , 871265. 871C2044 Zhang, Z. Y.. 871C2056 Zhao, K. H., 87!1986 Zhao, W.. 8711890 Zhao, X . , 87024 Zhao, Y., 8712081 Zhcbrakov, D. N., 8711270 Zhcn. R. Q., 8711984 Zheng, X..87iC2044 Zhcng, Y., 871585. 8711487, Zhong, X., 871326 Zhong, Y.. 871274, 871485. Zhou. D.. 871453 Zhou. J . , 871243 871C2056 871 1977 871584 87120 13 871 1493 Zhou, M., 871243 Zhou, Y., 871336 Zhou, Z . , 871273, 871607, Zhu. B . . 871237 Zhu, D.. 871241 Zhu, M.. 87/82 Zhu, w., 871937 Zhukova, N. G., 8712012 Zibarova, Yu. F., 871322 Zicai, C., 871633, $71965 Zihlmann, J., 8711893 Zil'bershtein. Kh. I., 87196, Zil'bcrstein, Ch. I.. 87/C1153 Zima, S., 871C1067 Zimmer. K., 871957, 87/C 1095, 871C 1 12 1 Zimmerli, B., 871C1846 Zimmcrmann, R.. 87lC1028 Zizak, G., 871955, 871956 Zoellner. M., 871C816 Zolotarcva, N. I . , 871394 Zolotov, Yu. A . , 871408. 871474, 871977, 8711 190 Zorn. H . , 8711687 Zorov. N. B.. 8711484 Zou, J . , 871943 Zoumboulis. A. I.. 871489 Zumkley.H., 871C1868 Zurera-Cosano, G., 871503 Zwanziger, H., 871C1001 Zybin. A. V., 871126. 871260, 871C 1 122. 871 1548 Zyrnicki. W., 871C1054, 871C 1057 871938 871327 Typeset and printed by Black Bear Press Limited, Cambridge, England42 ASU REFERENCE INDEX VOL. 2 (1987) Xu, Yi., 8711226 Xu, Z . , 871.536, 871937 Xue, H . , 871237 Yakimova, N . M., 871970 Yamada, H., 871367 Yamada, K . , 871582. 8711271 Yamada, M., 8711903 Yamamoto, I.. 871244 Yamamoto, M., 871288, 871 1475, 871C 1623 Yamamoto, Y.. 871288, 871 1439 I 871 1475, 87lC 1623 Yamashita, H.. 871372 Yamazaki. H., 871252 Yamazaki. N., 871478 Yamazaki, S.. 8711692 Yan, D., 8711235 Yan, W. Z . , 8711983 Yanagihara, S . , 8712017 Yang, J . , 871273 Yang, L., 87i1449 Yang. M., 871275. 871530 Yang.M. H., 87/303, 871342 Yang, P.. 87lC1375 Yang, X., 87i265, 8711538. Yang, X. D., 8711890 Yang, Y.. 8711214. 8711538 Yang. Z . , 871532 Yao. J., 871524. 8711228 Yao, I,. , 871608 Yao. S., 871276 Yap, C. T., 8716.50 Yasuda. K., 871367 Y asuda, M I , 87lC 1623 Yasui, A . , 8711990 Yatcs, D. A . , 871C555, 87lC1343, 871C1668, 871C 167 1 871C2044 Yates, D. E., 87/88 Yatsenko, L. F.. 8711481 Ybanez, N., 8711240 Ycah, K. S.. 871919 Yeung. E. S . , 871653 Yi, J . , 8711448 Yngstriim. S . . 871287 Yokoi. S . , 8712017 Yokota, F., 8711440 Yonemoto, T., 871437 Yoo, A., 8711501 Yoo. Y. J., 87lC170 Yoon, R.-H.. 871C1630 Yoshida, H., 8711546, 8711547, 8711954 Yoshida, Z . , 871377 Yoshimura, C . , 8711302 Yoshimura, E., 8711692 Yoshimura, K . , 87180 Yoshino, T., 8711582 Yotsuyanagi, T., 8711579 You.S . , 8711226 You, Y . , 871528 Yu. G. X., 8711983 Yu, H.. 871593 Yu, X. Z.. 8711906 Yuan, Z.-N., 871383 Yudclcvich, I. G., 871936, Yurko. R. J . . 87lC558 Zagatto, E. A. G., 871438 Zailaf, M., 8711534 Zakhariya, A. N., 8711901 Zakrevskaya. L. V . . 8711899 Zakrzcwski, Z., 87171 Zalts, A., 87152 Zandcr. A. T., 871123. 871666 Zander. U . , 87lC1000 Zaray, G., 871C1365 871 1482 Zaruba, K., 871C1866 Zauke, G. P., 8711064 Zawadzka, T., 8711315 Zeeman, P. B., 87165 Zclentsova, L. V., 8711482 Zendehnam, A., 871C193 Zeng, X. J.. 8711978, Zhan, G., 87024, 871337, Zhang, C. S.. 8711981 Zhang, €4. U., 8712098 Zhang, J . , 871939 Zhang, J . M., 8711883 Zhang, L.. 871492 Zhang, L. X., 8711981 Zhang, P., 871241 Zhang, Q., 871930 Zhang, S.. 8 7 / 3 3 , 871362, Zhang, W..87182 Zhang, X . , 871502 Zhang, Y., 871502, 871526 Zhang, Z . , 871265. 871C2044 Zhang, Z. Y.. 871C2056 Zhao, K. H., 87!1986 Zhao, W.. 8711890 Zhao, X . , 87024 Zhao, Y., 8712081 Zhcbrakov, D. N., 8711270 Zhcn. R. Q., 8711984 Zheng, X.. 87iC2044 Zhcng, Y., 871585. 8711487, Zhong, X., 871326 Zhong, Y.. 871274, 871485. Zhou. D.. 871453 Zhou. J . , 871243 871C2056 871 1977 871584 87120 13 871 1493 Zhou, M., 871243 Zhou, Y., 871336 Zhou, Z . , 871273, 871607, Zhu. B . . 871237 Zhu, D.. 871241 Zhu, M.. 87/82 Zhu, w., 871937 Zhukova, N. G., 8712012 Zibarova, Yu. F., 871322 Zicai, C., 871633, $71965 Zihlmann, J., 8711893 Zil'bershtein. Kh. I., 87196, Zil'bcrstein, Ch. I.. 87/C1153 Zima, S., 871C1067 Zimmer. K., 871957, 87/C 1095, 871C 1 12 1 Zimmerli, B., 871C1846 Zimmcrmann, R..87lC1028 Zizak, G., 871955, 871956 Zoellner. M., 871C816 Zolotarcva, N. I . , 871394 Zolotov, Yu. A . , 871408. 871474, 871977, 8711 190 Zorn. H . , 8711687 Zorov. N. B.. 8711484 Zou, J . , 871943 Zoumboulis. A. I.. 871489 Zumkley. H., 871C1868 Zurera-Cosano, G., 871503 Zwanziger, H., 871C1001 Zybin. A. V., 871126. 871260, 871C 1 122. 871 1548 Zyrnicki. W., 871C1054, 871C 1057 871938 871327 Typeset and printed by Black Bear Press Limited, Cambridge, England42 ASU REFERENCE INDEX VOL. 2 (1987) Xu, Yi., 8711226 Xu, Z . , 871.536, 871937 Xue, H . , 871237 Yakimova, N . M., 871970 Yamada, H., 871367 Yamada, K . , 871582. 8711271 Yamada, M., 8711903 Yamamoto, I.. 871244 Yamamoto, M., 871288, 871 1475, 871C 1623 Yamamoto, Y.. 871288, 871 1439 I 871 1475, 87lC 1623 Yamashita, H..871372 Yamazaki. H., 871252 Yamazaki. N., 871478 Yamazaki, S.. 8711692 Yan, D., 8711235 Yan, W. Z . , 8711983 Yanagihara, S . , 8712017 Yang, J . , 871273 Yang, L., 87i1449 Yang. M., 871275. 871530 Yang. M. H., 87/303, 871342 Yang, P.. 87lC1375 Yang, X., 87i265, 8711538. Yang, X. D., 8711890 Yang, Y.. 8711214. 8711538 Yang. Z . , 871532 Yao. J., 871524. 8711228 Yao, I,. , 871608 Yao. S., 871276 Yap, C. T., 8716.50 Yasuda. K., 871367 Y asuda, M I , 87lC 1623 Yasui, A . , 8711990 Yatcs, D. A . , 871C555, 87lC1343, 871C1668, 871C 167 1 871C2044 Yates, D. E., 87/88 Yatsenko, L. F.. 8711481 Ybanez, N., 8711240 Ycah, K. S.. 871919 Yeung. E. S . , 871653 Yi, J . , 8711448 Yngstriim. S . . 871287 Yokoi. S . , 8712017 Yokota, F., 8711440 Yonemoto, T., 871437 Yoo, A., 8711501 Yoo.Y. J., 87lC170 Yoon, R.-H.. 871C1630 Yoshida, H., 8711546, 8711547, 8711954 Yoshida, Z . , 871377 Yoshimura, C . , 8711302 Yoshimura, E., 8711692 Yoshimura, K . , 87180 Yoshino, T., 8711582 Yotsuyanagi, T., 8711579 You. S . , 8711226 You, Y . , 871528 Yu. G. X., 8711983 Yu, H.. 871593 Yu, X. Z.. 8711906 Yuan, Z.-N., 871383 Yudclcvich, I. G., 871936, Yurko. R. J . . 87lC558 Zagatto, E. A. G., 871438 Zailaf, M., 8711534 Zakhariya, A. N., 8711901 Zakrevskaya. L. V . . 8711899 Zakrzcwski, Z., 87171 Zalts, A., 87152 Zandcr. A. T., 871123. 871666 Zander. U . , 87lC1000 Zaray, G., 871C1365 871 1482 Zaruba, K., 871C1866 Zauke, G. P., 8711064 Zawadzka, T., 8711315 Zeeman, P. B., 87165 Zclentsova, L. V., 8711482 Zendehnam, A., 871C193 Zeng, X.J.. 8711978, Zhan, G., 87024, 871337, Zhang, C. S.. 8711981 Zhang, €4. U., 8712098 Zhang, J . , 871939 Zhang, J . M., 8711883 Zhang, L.. 871492 Zhang, L. X., 8711981 Zhang, P., 871241 Zhang, Q., 871930 Zhang, S.. 8 7 / 3 3 , 871362, Zhang, W.. 87182 Zhang, X . , 871502 Zhang, Y., 871502, 871526 Zhang, Z . , 871265. 871C2044 Zhang, Z. Y.. 871C2056 Zhao, K. H., 87!1986 Zhao, W.. 8711890 Zhao, X . , 87024 Zhao, Y., 8712081 Zhcbrakov, D. N., 8711270 Zhcn. R. Q., 8711984 Zheng, X.. 87iC2044 Zhcng, Y., 871585. 8711487, Zhong, X., 871326 Zhong, Y.. 871274, 871485. Zhou. D.. 871453 Zhou. J . , 871243 871C2056 871 1977 871584 87120 13 871 1493 Zhou, M., 871243 Zhou, Y., 871336 Zhou, Z . , 871273, 871607, Zhu. B . . 871237 Zhu, D.. 871241 Zhu, M..87/82 Zhu, w., 871937 Zhukova, N. G., 8712012 Zibarova, Yu. F., 871322 Zicai, C., 871633, $71965 Zihlmann, J., 8711893 Zil'bershtein. Kh. I., 87196, Zil'bcrstein, Ch. I.. 87/C1153 Zima, S., 871C1067 Zimmer. K., 871957, 87/C 1095, 871C 1 12 1 Zimmerli, B., 871C1846 Zimmcrmann, R.. 87lC1028 Zizak, G., 871955, 871956 Zoellner. M., 871C816 Zolotarcva, N. I . , 871394 Zolotov, Yu. A . , 871408. 871474, 871977, 8711 190 Zorn. H . , 8711687 Zorov. N. B.. 8711484 Zou, J . , 871943 Zoumboulis. A. I.. 871489 Zumkley. H., 871C1868 Zurera-Cosano, G., 871503 Zwanziger, H., 871C1001 Zybin. A. V., 871126. 871260, 871C 1 122. 871 1548 Zyrnicki. W., 871C1054, 871C 1057 871938 871327 Typeset and printed by Black Bear Press Limited, Cambridge, England42 ASU REFERENCE INDEX VOL. 2 (1987) Xu, Yi., 8711226 Xu, Z ., 871.536, 871937 Xue, H . , 871237 Yakimova, N . M., 871970 Yamada, H., 871367 Yamada, K . , 871582. 8711271 Yamada, M., 8711903 Yamamoto, I.. 871244 Yamamoto, M., 871288, 871 1475, 871C 1623 Yamamoto, Y.. 871288, 871 1439 I 871 1475, 87lC 1623 Yamashita, H.. 871372 Yamazaki. H., 871252 Yamazaki. N., 871478 Yamazaki, S.. 8711692 Yan, D., 8711235 Yan, W. Z . , 8711983 Yanagihara, S . , 8712017 Yang, J . , 871273 Yang, L., 87i1449 Yang. M., 871275. 871530 Yang. M. H., 87/303, 871342 Yang, P.. 87lC1375 Yang, X., 87i265, 8711538. Yang, X. D., 8711890 Yang, Y.. 8711214. 8711538 Yang. Z . , 871532 Yao. J., 871524. 8711228 Yao, I,. , 871608 Yao. S., 871276 Yap, C. T., 8716.50 Yasuda. K., 871367 Y asuda, M I , 87lC 1623 Yasui, A ., 8711990 Yatcs, D. A . , 871C555, 87lC1343, 871C1668, 871C 167 1 871C2044 Yates, D. E., 87/88 Yatsenko, L. F.. 8711481 Ybanez, N., 8711240 Ycah, K. S.. 871919 Yeung. E. S . , 871653 Yi, J . , 8711448 Yngstriim. S . . 871287 Yokoi. S . , 8712017 Yokota, F., 8711440 Yonemoto, T., 871437 Yoo, A., 8711501 Yoo. Y. J., 87lC170 Yoon, R.-H.. 871C1630 Yoshida, H., 8711546, 8711547, 8711954 Yoshida, Z . , 871377 Yoshimura, C . , 8711302 Yoshimura, E., 8711692 Yoshimura, K . , 87180 Yoshino, T., 8711582 Yotsuyanagi, T., 8711579 You. S . , 8711226 You, Y . , 871528 Yu. G. X., 8711983 Yu, H.. 871593 Yu, X. Z.. 8711906 Yuan, Z.-N., 871383 Yudclcvich, I. G., 871936, Yurko. R. J . . 87lC558 Zagatto, E. A. G., 871438 Zailaf, M., 8711534 Zakhariya, A. N., 8711901 Zakrevskaya. L.V . . 8711899 Zakrzcwski, Z., 87171 Zalts, A., 87152 Zandcr. A. T., 871123. 871666 Zander. U . , 87lC1000 Zaray, G., 871C1365 871 1482 Zaruba, K., 871C1866 Zauke, G. P., 8711064 Zawadzka, T., 8711315 Zeeman, P. B., 87165 Zclentsova, L. V., 8711482 Zendehnam, A., 871C193 Zeng, X. J.. 8711978, Zhan, G., 87024, 871337, Zhang, C. S.. 8711981 Zhang, €4. U., 8712098 Zhang, J . , 871939 Zhang, J . M., 8711883 Zhang, L.. 871492 Zhang, L. X., 8711981 Zhang, P., 871241 Zhang, Q., 871930 Zhang, S.. 8 7 / 3 3 , 871362, Zhang, W.. 87182 Zhang, X . , 871502 Zhang, Y., 871502, 871526 Zhang, Z . , 871265. 871C2044 Zhang, Z. Y.. 871C2056 Zhao, K. H., 87!1986 Zhao, W.. 8711890 Zhao, X . , 87024 Zhao, Y., 8712081 Zhcbrakov, D. N., 8711270 Zhcn. R. Q., 8711984 Zheng, X.. 87iC2044 Zhcng, Y., 871585. 8711487, Zhong, X., 871326 Zhong, Y.. 871274, 871485. Zhou. D.. 871453 Zhou. J . , 871243 871C2056 871 1977 871584 87120 13 871 1493 Zhou, M., 871243 Zhou, Y., 871336 Zhou, Z . , 871273, 871607, Zhu. B . . 871237 Zhu, D.. 871241 Zhu, M.. 87/82 Zhu, w., 871937 Zhukova, N. G., 8712012 Zibarova, Yu. F., 871322 Zicai, C., 871633, $71965 Zihlmann, J., 8711893 Zil'bershtein. Kh. I., 87196, Zil'bcrstein, Ch. I.. 87/C1153 Zima, S., 871C1067 Zimmer. K., 871957, 87/C 1095, 871C 1 12 1 Zimmerli, B., 871C1846 Zimmcrmann, R.. 87lC1028 Zizak, G., 871955, 871956 Zoellner. M., 871C816 Zolotarcva, N. I . , 871394 Zolotov, Yu. A . , 871408. 871474, 871977, 8711 190 Zorn. H . , 8711687 Zorov. N. B.. 8711484 Zou, J . , 871943 Zoumboulis. A. I.. 871489 Zumkley. H., 871C1868 Zurera-Cosano, G., 871503 Zwanziger, H., 871C1001 Zybin. A. V., 871126. 871260, 871C 1 122. 871 1548 Zyrnicki. W., 871C1054, 871C 1057 871938 871327 Typeset and printed by Black Bear Press Limited, Cambridge, England

ISSN:0267-9477    

DOI:10.1039/JA98702BP005

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

6 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 Conference Report 1 I t h National Conference on Spectrochemical Excitation and Analysis: 2nd-5th September, 1986, Edgartown, Martha‘s Vineyard, MA, USA This conference began in 1976 as the New England Conference on Spectrochemical Excitation and Analysis; the first meeting was held in Newport, Rhode Island and it was a one day round table event. The conference organisers, Thomas R. Gil- bert, Hank Griffin, Richard Kennally and Walter Cox, did not intend to start an annual meeting. Owing to the success of the first meeting, however, it was decided to hold a second meeting in 1977; this was held at the New England Aquarium in Boston. In 1978, the meeting was held in Woods Hole, Massachusetts; the 1979 meeting was held in Groton, Connecticut at which time it became the National Conference on Spectrochemical Excita- tion and Analysis.In 1980, the conference returned to the New England Aquarium. At this point it was decided that the conference should be held in the same location each year and since 1981, the conference has been held on the island of Martha’s Vineyard off the coast of Cape Cod, Massachusetts. Since 1981, the meeting has been run by Mr. Hank Griffin of Texas Instruments and the meeting is held each year just after the American “Labor Day” holiday in early September. The conference is held at the delightful Harbor View Hotel in Edgar- town on the east wide of the island. This conference might best be des- cribed as a “sleeper” meeting as it is not large and not too well known.It is, however, an “enthusiastic” meeting with much cross-talk and informal discussion among attendees. The quality of papers over the years has been excellent. It should be noted that commercial type presentations are strongly discouraged. This year’s meeting began with a session on Tuesday, September 2nd, on environ- mental analysis chaired by Thomas R. Gilbert of Northeastern University. Mucklow (IBM) presented a particularly interesting paper describing waste-water analysis by ICP and DCP techniques and Miller (Enviresponse Inc.) discussed the determination of priority pollutant metals by DCP techniques. On Wednesday morning, Leighty (Thermo Jarrell-Ash) chaired a session entitled “Atomic Spec- troscopy with the ICP-AES” and Slavin (Perkin-Elmer) presented a particularly interesting paper on the selection of a laboratory spectrometer for elemental analysis.Davidowski (Perkin-Elmer) des- cribed automatic optimisation of ICP operating conditions and Skrabak (Baird Corporation) discussed applications of ICP atomic fluorescence spectrometry for the determination of precious metals. The session concluded with a paper by Leighty on the analysis of organic solvents by ICP-AES. The Wednesday afternoon ses- sion was on recent advances in sample introduction and several interesting pap- ers were presented. Gilbert (North- eastern) evaluated a platinum grid nebu- liser for ICP-AES and Evans (Baird Corporation) described recent work with ultrasonic nebulisers. Anderau (Perkin- Elmer) compared various nebulisers designed for high-solids matrices and Uhr (Leeman Labs) used a continuous flow hydride generation device to determine various metals with ICP-AES.The ses- sion concluded with an excellent paper by Michel (University of Connecticut) dis- cussing carbon furnace sample introduc- tion for the metastable nitrogen plasma. The Thursday morning session was devoted to new sources and spectromet- ers. Belliveau (Providence College) presented a paper on laser-induced break- down spectroscopy (LIBS) of aqueous and ceramidglass samples at atmospheric pressure and in air, Gilbert (North- eastern) described a novel rotating disk electrode for the analysis of lubricating oils and Routh (ARL) presented two papers on various aspects of ICP Fourier transform spectrometry.Lyke (PRA International) discussed detection limits and figures of merit for a photodiode detector echelle ICP spectrometer. In the morning’s final paper, Leighty (Thermo Jarrell-Ash) described some new applica- tions of the Smith - Hieftje background correction AAS system. The Thursday afternoon session was devoted to DCP techniques. Krull (Northeastern) des- cribed an inexpensive interfacing of gas chromatography with the DCP for the determination of methylmercury in fish. In a very pragmatic paper, Klales (Brandywine Instrumentation Company) described maintenance and simple repair procedures that could easily be used to repair DCP echelle spectrometers. Kin- sey (ARL) described an automated hand- ling system that could easily be interfaced to DCP spectrometers.The meeting concluded on Friday morning, September 5th, with a session organised by Gerry DeMenna (Beckman) on DCP-AES analytical techniques. Clif- ford (Villanova University) utilised com- ponents from an inexpensive “Mr. Cof- fee” machine (a popular American coffee maker) to stabilise a DCP echelle spec- trometer. Centrella (General Battery Corporation) determined various impuri- ties in lead and sulphuric acid for the storage battery industry and Perrone (Tufts University) described applications of DCP-AES to metabolic research and studies of clinical nutrition. In a related paper, McEwen (Tufts University) dis- cussed applications of sequential reading DCP-AES to the clinical and biomedical research laboratory. Finally, Olear (Texas Instruments) described selenium determination using a hydride generator.This meeting is held in a superb loca- tion at the right time of year. The registra- tion fee (US$450 in 1986) includes hotelJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 7 SECOND SURREY CONFERENCE ON PLASMA SOURCE MASS SPECTROMETRY University of Surrey, Guildford, Surrey, UK 6th-8th July, 1987 The second Surrey Conference will be devoted solely to ICP Source Mass Spectrometry. The conference will include invited and contributed papers, a workshop and a short course. Papers are invited and abstracts (250 words) should be submitted by 31st March 1987. Intending speakers are encouraged to take advantage of the opportunity to publish their texts in an issue of JAAS. Further information from: Or.A. L. Gray, Department of Chemistry, University of Surrey, Guildford, Surrey GU2 5XH, UK. Analytical Journals Published by The Royal Society of Chemistry Subscription Rates 1987 The Analyst 12 issues per annum plus index f 160.00 ($31 5.00) Rest of World f 179.00 RSC members €32.00 Analytical Abstracts 12 issues per annum plus index f239.00 ($463.00) Rest of World f263.00 RSC members €62.50 Analytical Proceedings 12 issues per annum plus index f75.00 ($148.00) Rest of World €84.00 RSC members f 1 1.50 Journal of Analytical Atomic Spectrometry (JAAS) 6 issues per annum plus two special issues 1987, plus index f 180.00 ($356.00) Rest of World f202.00 RSC members f36.00 Special Packages (Non-RSC members only) The Analyst, Analytical Abstracts and Proceedings €41 1 .OO ($801 .OO) Rest of World $455.00 The Analyst and Analytical Abstracts f364.00 ($709.00) Rest of World €403.00 The Analyst and Proceedings f200.00 ($394.00) Rest of World f224.00 N.B.The version of Analytical Abstracts printed on one side of the page only is no longer available. ROYAL SOCIETYOF Information Services Orderlng : Non-RSC members should send their orders to The Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 1 HN, U K RSC members should send their orders to The Royal Society of Chemistry, Membership Manager, 30 Russell Square, London WClB 5DT, U K8 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 accommodation and three delicious meals appreciated by all. The 1987 National Hank Griffin, Texas Instruments, MS each day.The seafood specialities of the Conference on Spectrochemica1 Excita- 10-16, 39 Forest Street, Attleboro, MA hotel (lobster, shrimp, swordfish, etc.) tion and Analysis will be held in Martha’s 02703, USA. are particularly delicious. A clambake Vineyard once again at the same location Peter N. Keliher was held on Thursday evening of the from September 8th to 11th. Information Villanova University, conference and was an outstanding event on the meeting may be obtained from Mr. Villanova, PA, USA _ _ ~ ASU Highlights Environmental analysis by atomic spec- trometry is the theme of the ASU review in this issue. The application of, princi- pally, AAS, AFS and AES (with arcs, sparks, plasmas, flames, furnaces and lasers) as well as ICP-MS, to the monitor- ing of the air, atmospheric particulates, waters, including sea and river water and effluents, soils, plants, fertilisers and re- lated materials is reviewed over a 12- month period.For the first time in an ASU review an abbreviated form of the reference is provided at the foot of the review as an additional aid to the reader. While there have been technique advances across a broad range in the past year, some of the more notable develop- ments have concerned the direct intro- duction of samples other than liquids, particularly solids, powders, aerosols and gases, into a variety of different atom cells. This is clearly consistent with the dominant trend which the reader of the review will discern, the demand for faster analysis. The growth of interest in rapid multi-element techniques which can be readily automated is clearly evidenced from the papers reported. While this is understandable given the growing demand for environmental monitoring during an era of tight financial con- straints, this does emphasise the need for a greater awareness of quality control procedures. In this context it is encourag- ing to report several new environmental CRMs even though more are required, and a number of inter-laboratory com- parisons even if these have been slow to develop. Les Ebdon Plymouth Polytechnic, UK Society for Analytical Chemistry Gold Medal The 18th SAC Gold Medal has been awarded to Dr. Alan L. Gray of the University of Surrey, Guildford, UK.

ISSN:0267-9477    

DOI:10.1039/JA9870200006

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

8 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 Conferences and Meetings Users’ Meeting: Plasma Spectrometry brief presentations should be submitted March 26-27, 1987, Dortmund, FRG by 1st March 1987. For further informa- A meeting will be held at the Institut fiir tion contact Dr. J. A. C . Broekaert, Spektrochemie und angewandte Spek- Institut fur Spektrochemie und ange- troskopie, in collaboration with the wandte Spektroskopie, Postfach 778, “Deutsche Arbeitskreis fiir angewandte D-4600 Dortmund 1, FRG. Spektroskopie (DASp),” of users and manufacturers of instruments for plasma spectral analysis (ICP, CMP, DCP, MIP) at which participants can report on their Third l ~ o - H W ! a * ~ Symposium on experiences and problems and exchange Spwtrmhemistry: Biomedical Research information.The intention is that partici- and SFtrochemistry pants will be able to give short talks, June g12, 1987, Ispru (Vurese), Italy which will be discussed according to topic Scientific cooperation between Italy and area. Hungary has been increasingly fruitful The meeting begins on 26th March 1987 since its inception. This third Symposium at 2 p.m. and ends on 27th March 1987 at on Spectrochemistry, very much along the 1.30 p.m., and there is no charge. On both same lines as previous meetings, aims at days lunch will be available in the canteen providing a forum of the most recent of the Institut fur Arbeitsphysiologie, advancement of both partners in this which is near the Institute. Hotel reserva- field, while discussing and planning tions can be made through the Dort- further joint efforts of mutual benefit.As munder Verkehrsverein (Quartiernach- usual in this series, emphasis will be laid weis), Konigswall 18, 4600 Dortmund 1 on the role played by spectrochemical (telephone 0231 140341). techniques in assisting, performing and Applications and proposed titles of expanding a major field of research, i.e., biomedicine in its broadest sense. Consequently, investigation of the mechanism of fundamental biochemical processes and of their malfunctions, insurgence of pathological states, epi- demiological aspects of environmental pollution, in other words all facets of disease prevention and health mainte- nance, will be dealt with from the stand- point of the extensive support, often essential, which is afforded by spectro- chemistry.Current trends in this area will be presented through approximately 20 invited lectures forming the main body of the event, while poster sessions focusing on more specific topics are also envisaged. The Symposium will offer a useful opportunity for scientists from both coun- tries to become acquainted with multi- faceted research of their colleagues and hopefully lead to further enhancement of collaborative programmes. Finally, the expected participation of prominent rep- resentatives from other countries will add international imprint to the meeting.JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 9 The conference language will be English, although lectures may also be given in French or German. All correspondence concerning the scientific programme or enquiries about attending the Symposium should be addressed directly to: S.Caroli, Labora- torio di Tossicologia Applicata, Istituto Superiore di Sanith, Viale Regina Elena 299, 00161 Rome, Italy. XXV Colloquium Spectroscopicum Inter- nationale June 21-26, 1987, Toronto, Canada The XXV CSI will be held at the Hilton Harbour Castle, Toronto, Canada. This North American CSI is sponsored by the Spectroscopy Society of Canada, the Society for Applied Spectroscopy (USA) and the National Research Council of Canada. Nobel Laureates Dr. Gerhard Herz- berg and Professor Arthur L. Schawlow will each present a plenary lecture. Invited lectures on current research topics will be given by approximately 35 young spectroscopists who are making major contributions to the field of atomic and molecular spectroscopy, including: N.Armstrong (Univ. of Arizona), G. 1. Bekov (Academy of Sciences, USSR), T. Berthoud (Centre d’Etudes Nucleaires, France), M. Blades (Univ. of British Columbia), M. A. Bolshov (Academy of Sciences, USSR), J. A. C. Broekaert (Inst. f. Spektrochemie & angewandte Spektros- kopie, FRG), D. C. Compton (Standard Oil Company), G. De Loos (Lab. voor Analytische Scheikunde, The Nether- lands), N. J. Dovichi (Univ. of Wyom- ing), R. Garrel (Univ. of Pittsburgh), J. M. Harris (Univ. of Utah), J. A. Holcombe (Univ. of Texas), D. E. Honigs (Univ. of Washington), S. Houk (Iowa State Univ.), B. Huang (Chang- chun Inst. of Applied Chemistry, China), T. Imasaka (Kyushu Univ.of Japan), K. Kitagawa (Nagoya, Japan), L. B. McGown (Oklahoma State Univ.), J. W. McLaren (National Research Coun- cil Canada), R. Miller (Unilever, UK), J. M. Ramsey (Oak Ridge National Lab.), J. P. Reilly (Indiana Univ.), A. Scheeline (Univ. of Illinois), D. C. Schram (Philips Research Labs., The Netherlands), R. Sturgeon (National Research Council Canada), T. Vo-Dinh (Oak Ridge National Lab.), I. M. Warner (Emory Univ.) and E. S. Yeung (Iowa State Univ.). For further information on the pro- gramme contact Dr. J. D. Wineforder, Department of Chemistry, University of Florida, Gainesville , FL 3261 1, USA. Symposia are planned for after the Colloquium, with four confirmed to date: ICP-MS; Line Spectra of the Elements; Graphite Furnace Atomic Spectroscopy; and FT and Raman Spectroscopy.There will be an exhibition of scientific instrumentation, services and publica- tions. For exhibition information contact either Dr. Andrew T. Zander, Perkin- Elmer Corporation (MS905), 761 Main Avenue, Norwalk, CT 06859-0905, USA or Dr. Andrew W. Boorn, Sciex Incor- porated, 55 Glen Cameron Road, Thorn- hill, Ontario L3T 1P2, Canada. A social programme is being prepared and will include a dinner, receptions and tours; Wednesday June 24th is an excursion day. For any further information, including registration, contact Mr. L. Forget, Conference Services Office , National Research Council Canada, Ottawa, Ontario K1A OR6, Canada. Graphite Furnace Atomic Absorption: Post-CSI Symposium June 28-July 2, 1987, Huntsville, Ontario, Canada A conference dealing with various aspects of graphite furnace atomic absorption will be held following the XXV CSI meeting.Three full days of talks and panel discus- sions are planned in addition to selected opportunities to enjoy the surrounding countryside. A number of the world’s leading researchers in GFAA have been invited to present their work. Two open panel discussion sessions are included in the programme to permit topical coverage which may be of interest to the attendees but not covered in enough detail during the preceding day. These sessions have been designed ( a ) to encourage participation by all who are in attendance and (b) to move in the direc- tion dictated by the interests of the audience. The meeting will be flexibly structured to allow ample time for discussion amongst the speakers and conferees. The slate of invited speakers and topics will broadly cover the field of graphite furnace atomic absorption.The areas explored by the meeting will include: (1) fundamental processes occurring in the furnace with their applications and implications toward analyses; (2) new analytical approaches for GFAA (e.g. , direct solids analysis and absolute analysis); and (3) future analy- tical prospects for GFAA. Panelists and speakers include the fol- lowipg invited scientists: H. Berndt (FRG), A. A. Brown (UK), C. Chakra- barti (Canada), H. T. Delves (UK), K. Dittrich (GDR), H. Falk (GDR), W. Frech (Sweden), J. M. Hardy (USA), J. A. Holcombe (USA), C. Huie (USA), K. W. Jackson (Canada), T. Kantor (Hungary), S. R.Koirtyohann (USA), U. Kurfurst (FRG), R. Lovett (USA), E. Lundberg (Sweden), B . L’vov (USSR), N. J. Miller-Ihli (USA), G. Muller-Vogt (FRG), H. Ortner (Austria), C. J. Rademeyer (RSA), T. Rains (USA), G. D. Rayson (USA), D. E. Shrader (USA), D. Siemer (USA), W. Slavin (USA), J. Sotera (USA), R. E. Sturgeon (Canada), D. Styris (USA), G. Tessari (Italy), B. Welz (FRG) and W. Wend1 (FRG). There is a $100 (CND) registration fee and accommodation will be approxi- mately $116 (CND) per night (single) or $96 (CND) per night (double occupancy). These prices include lodging, gratuities and meals during the conference. Group social functions as well as dining on-site have been made an integral part of the three days to maximise the opportunity for interactions between conferees.A mixer will be held Sunday evening and a group social event is planned for Wednes- day evening. Hidden Valley Resort Hotel is located on Peninsula Lake and is equipped with jogging trails, boating, etc. Hotel and meeting room space is limited and registrations will be accepted on a first-come first-served basis. Regis- tration information will be contained in the final CSI bulletin to be distributed in January, 1987 or more information can be obtained by writing to Dr. James Holcombe, Department of Chemistry, University of Texas, Austin , Texas 78712, USA or Dr. Ralph Sturgeon, Division of Chemistry, National Research Council of Canada, Ottawa, Ontario K1A OR9, Canada. Inductively Coupled Plasma Mass Spec- troscopy: Post-CSI Symposium June 28-30, 1987, Lake Muskoka, Canada A symposium, sponsored by the Spectro- scopy Society of Canada in conjunction with the XXV Colloquium Spectroscopi- cum Internationale will be held on appli- cations and development of ICP-MS as an analytical technique immediately follow- ing the XXV CSI being held in Toronto, June 21-26, 1987.The symposium will take place at the Muskoka Sands Inn, a resort and conven- tion centre two hours drive north of Toronto on scenic Lake Muskoka. Jim McLaren (National Research Council of Canada) and Chris Riddle (Ontario Geo- logical Survey) are the Symposium Chair- persons. Six invited speakers will present their latest development work in the opening session: Don Douglas (SCIEX) , Alan Gray (University of Surrey), Gary Hor- lick (University of Alberta), Sam Houk (Iowa State University), Jean-Michel Mermet (UniversitC Claude Bernard, Lyon) and George Vickers (Indiana Uni- versity).Short original “applications- oriented” papers are being sought from active ICP-MS users for the afternoon session of the first day. It is intended that all symposium presentations shall be original and of high quality as refereed publication of the proceedings will follow the symposium. Paper titles are requested now, a working abstract by April 1987 and the full text of the paper is required by June 12, 1987.10 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 Ramon M. Barnes, Editor Department of Chemistry GRC Towers U niversi t y of Massachusetts Amherst, MA 01003.9035 Tel. (413) 545-2294 Objective The lCP lnformation Newsletter is a monthly journal published by the Plasma Research Group at the University of Massachu- setts and is devoted exclusively to the rapid and impartial dissem- ination of news and literature information related to the devel- opment and applications of plasma sources for spectrochemical analysis.Background ICP stands for inductively coupled plasma discharge, which dur- ing the past decade has become the leading spectrochemical excitation source for atomic emission spectroscopy. ICP sources are also applied commercially as an atom and ion cell in atomic fluorescence spectrometry and as an ion source for mass spec- trometry. 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 omhe ICP lnformation Newsletter in 1975.Other plasma sources, such as microwave induced plas- mas and direct current plasma jets, have also grown in popularity and are included in the scope of the ICP lnformation Newsletter. scope As the only authoritative monthly journal of its type, the ICP lnformation Newsletter is read in more than 40 countries by scientists actively applying or planning to use the ICP or other types of plasma spectroscopy. For the novice in the field, the ICP lnformation Newsletter provides a concise and systema- tic source of information and background material needed for the selection of instrumentation or the development of new meth- odology. Edltorial The ICP lnformation Newsletter is edited by Dr. Ramon M. Barnes, Professor of Chemistry, University of Massachusetts 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, view- points, and developments. Dr.Barnes has been conducting plasma research on ICP and other discharges since 1968. Healso serves as chairman of the Winter Conferences on Plasma Spectrochemistry. Regular Fe8tunr .Original submitted and invited research articles by ICP and plasma experts. Complete bibliography of all major ICP publications from 1961 to the present. Abstracts of all ICP papers presented at major US and interna- tional meetings. *First-hand accounts of ICP developments from na- tions around the world. Special reports on microwave and other plasma progress. Calendar and advanced programs of plasma meetings.Publication of plasma-related patents. .Technical translations and reprints of critical foreign- Critical reviews of plasma-related books. language ICP papers. Conference Activities The lCP lnformation Newsletter has sponsored five international meetings on developments in atomic plasma spectrochemical analysis since 1980 in San Juan, Orlando, San Diego, Leysin, Switzerland, and Kailua-Kona, HI. Meeting proceedings have ap- peared as Developments in Atomic Plasma Spectrochemical Analysis (Wi ley), Plasma Specfrochemistry and Plasma Specfrochemistry I I (Pergamon Press) as well as in special issues of Spectrochimica Acta, Part B. Subscription lnformation 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 12 runs from June 1986 through May 1987. Back issues beginning with Volume 1, May 1975 are also available. To begin a subscription, complete the attached order form, and submit it with prepayment or purchase in- formation. For additional information please call (41 3) 545-2294 or contact the Editor. Detach and send to: ICP lnformation Newdetter, Dr. Ramon M. Barnes Department of Chemistry, GRC Towers, University of Massachusetts, Amherst, MA 01003-0035 Telephone (413) 545-2294 Start a subscription for the following issues (complete): [ ] Volume(s) - (June 198-- May 198-) [ ] 198- (January-December) or I enclose: [ J prepayment or [ J purchase order (No.1 or [ ] Send invoice. Current subscription rates are $49 (North America), $69 (Europe, South America), or $75 (Africa, Asia, Indian/Pacific Ocean Areas, Middle East, and USSR). Back issues rates available on request.JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 11 The second day will involve break-out discussion groups with the invited speak- ers and a final, moderated panel discus- sion on the future of ICP-MS. The total cost, including registration, will be approximately $450.00 Canadian ($350.00 US) per person and includes accommodation (2 nights, double occu- pancy) with full board, an opening night dinner-cruise on Lake Muskoka, a lake- side barbecue, all symposium literature and a copy of the published proceedings.The day following the symposium is Canada Day, a national holiday, and for those wishing to stay on a conference room rate will be available. Spouses and family members will find plenty to do at the Muskoka Sands. To ensure a productive climate, and due to the physical limitations of the Muskoka Sands, registrations will be limited. To reserve your place and to be placed on the mailing list for further announcements please contact Dr. Chris Riddle, Chief Analyst, Geoscience Lab- oratories, Ontario Geological Survey, 77 Grenville Street, Room 1117, Toronto, Ontario M7A 1W4, Canada. Second Surrey Conference on Plasma Source Mass Spectrometry July 6-8, 1987, Guildford, Surrey, UK This is an advance notice of the Second Surrey Conference, Short Course and Workshop.Further details are available from Dr. A. L. Gray, Department of Chemistry, University of Surrey, Guild- ford, Surrey GU2 5XH, UK. Spectroscopy Across the Spectrum: Analytical Applications of Spectroscopy July 12-15,1987, Norwich, UK The Conference (incorporating The First International Near Infrared Spectroscopy Conference) will be held at the University of East Anglia, Norwich. The aim of the meeting is to bring together spectrosco- pists from many different disciplines with the propsect of an interchange of ideas and methods. The meeting will be organ- ised in three parts: general, poster and parallel specialist sessions. There will be an equipment exhibition and a social programme. An internationally recognised group of specialists have been invited to present the plenary and keynote lectures which cover the areas of: combined techniques, data analysis and Fourier transform spec- troscopy.Parallel sessions are planned in the following areas: near IR, atomic absorption, mass, NMR, microwave and IR spectroscopy, process control and chemometrics. Poster contributions are invited in any of these areas. For further information contact Dr. C. S. Creaser, School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, UK. Euroanalysis VI September 7-11, 1987, Paris, France Euroanalysis VI will be held at the Centre International de Confkrences in Paris. The plenary, keynote and contributed lectures will cover all aspects of analytical chemistry, but special sessions are planned to discuss: the use and construc- tion of analytical probes; applications of analytical methods for solving environ- mental problems; analysis of solid-state samples; and new methods of teaching analytical subjects (poster session). There will also be an exhibition and a social programme.Further information is available from GAMS, 88 Boulevard Malesherbes, 75008 Paris , France. FACSS XIV, 1987 October 4 9 , 1987, Detroit, MI, USA The 1987 FACSS meeting will be held at Cob0 Hall and the Westin Hotel in Detroit, Michigan. As in the past, work- shops and short courses will be offered prior to, during and after the conference. The FACSS Employment Bureau will again be available to conference atten- dees. Centrally located at the meeting will be an exhibition of scientific instrumenta- tion, services and publications.For further information contact the publicity chairman, Dr. Stephen J. Swarin, Pub- licity Chairman, Analytical Chemistry Dept., General Motors Research Labs., Warren, MI 48090-9055, USA, telephone 3 13-986-0806. Second Beijing Conference and Exhibition on Instrumental Analysis Conference October 20-23, 1987; exhibi- tion October 19-25, 1987, Beijing, China The objective of the Second BCEIA is to promote academic exchanges on instrumental analysis and friendly rela- tionships between scientists of various countries and technical and trade co-oper- ation between Chinese and foreign com- panies. Symposia will be held on electron microscopy, mass spectrometry, spectro- scopy, chromatography, radio- and microwave spectroscopy and electro- analytical chemistry.The Symposia will cover theories of analysis, new methods and techniques in instrumental analysis, research and development on instrumen- tation and their applications to industry, agriculture and all other areas. The official language of the conference will be English. Unpublished papers covering the areas given above are invited. Accepted abstracts (two pages) will be compiled and published in English in book form prior to the Conference. During the Conference a large scale exhibition of scientific instruments will be held, in which companies from all over the world will be exhibiting their latest products on electron microscopy, mass spectrometry, spectroscopy, chromato- graphy, radio- and microwave spectro- scopy and electroanalytical chemistry. Space will be provided for exhibitors to hold technical seminars and business talks. The space for the exhibition and seminars will cover an area of 10000 m2. The stand rents range from US$2500 to US$5000 per unit. Interpreters will be available for an extra fee for exhibitors. The Conference Registration Fee is US$l50, which will include admission to the conference and exhibition, a welcom- ing reception, entertainment, a copy of the abstract book containing all contri- buted papers and souvenirs. There will be an accompanying persons programme arranged by the Beijing Tour Agency. For further information contact the General Service Office, Second BCEIA, Room 4205, South Bldg. , Beijing Exhibi- tion Center Hotel, Beijing, China; Telex: 20056 BCEIA CN.

ISSN:0267-9477    

DOI:10.1039/JA9870200008

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 11 Course 24th Annual Short Summer Course in X-ray Spectrometry June 1-5, June 8-12 and August 17-21, 1987, Albany, NY, USA The 24th annual short course in Modern X-ray Spectrometry will be offered at the State University of New YoTk at Albany. The course is an integrated tutorial, start- ing from fundamentals, advancing by careful degrees to the latest developments in mathematical and computer techniques and emphasising practical applications. Both weeks illustrate and employ wavelength and energy dispersive methods equally. Equal time is devoted to lectures, laboratories and problem- solving workshops. The first week covers fundamentals principles and practice and prepares students to carry out any conceivable type of chemical analysis.The second week further develops principles and practice and emphasises the several techniques for absorption-enhancement corrections, including mathematical and computer. The third, August, week is devoted com- pletely to mathematical and computer methods for matrix correction. The tui- tion fees will be: $1100.00 each week, Sessions I and 11, and $1200.00, Session 111, payable in US dollars drawn on a US bank. To register and for further information contact Professor Henry Chessin, State University of New York at Albany, Department of Physics, 1400 Washington Avenue, Albany, NY 12222, USA.12 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 GORDON F. KIRKBRIGHT BURSARY FUND This fund was established in 1985 as a memorial to Gordon Kirkbright and his contributions to analytical spectroscopy and analytical science in general. The aim is to enable promising young analytical scientists of any nation to visit a recognised scientific meeting or place of learning in order to further their education. APPLICATIONS ARE INVITED FOR THE AWARD OF THE GORDON F. KIRKBRIGHT BURSARY While there are nof formal age restrictions on the award it is expected that the successful applicant wil be undertaking research towards a PhD or be in his or her first post-doctoral postion. either Please write for an application form to: Dr. N. W. Barnett (Vice-chairman of the Association of British Spectroscopists), Department of Environmental Sciences, Plymouth Polytechnic, Plymouth, Devon PL4 8AA, UK. The form must be completed and returned to the above address not later than March 31, 1987.

ISSN:0267-9477    

DOI:10.1039/JA9870200011

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

12 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 Future Issues will lnclude- The March Special Issue of JAAS will contain over 30 papers from the Third Biennial National Atomic Spectroscopy Symposium, Bristol, UK, July, 1986. The April issue will contain the following papers. Determination of Trace Amounts of Thorium and Uranium in Coal Ash by ICP-AES after TTA Extraction and Back-extraction with Dilute Nitric Acid- Eijiro Kamata The Determination of Rare Earth Ele- ments in Geological Samples by ICP- MS-A. R. Date and D. Hutchison Direct Determination of Cadmium in Urine by Electrothermal Atomisation Atomic Absorption Spectrometry-D. J. Halls, M. M. Black, G. S. Fell and (the late) J. M. Ottaway Plasma Potential Measurements for ICP- MS with a Centre-tapped Load Coil- R.S. Houk, J. K. Schoer and J. s. Crain Determination of Trace Metals in Marine Sediments by ICP-MS-J. W. McLaren, D. Beauchemin and S. S. Berman Direct Atomic Spectrometric Analysis by Slurry Atomisation. Part 2. Whole Coal Analysis by Inductively Coupled Plasma Atomic Emission Spectrometry-L. Ebdon and J. R. Wilkinson Determination of Phosphorus by Graph- ite Furnace Atomic Absorption Spec- trometry. Part 3. Analysis of Biological Materials-A. J. Curtius, G. Schlemmer and B. Welz Determination of Sulphur Compounds by Fully Automated Molecular Emission Cavity Analysis-N. P. Emiridis and A. Townshend The Use of a Thermospray Nebuliser as a Sample Introduction System for Induc- tively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)-K. A.Ver- meiren, P. D. P. Taylor and R. Dams The Determination of Copper in Biolog- ical Microsamples by Direct Solid Samp- ling Graphite Furnace Atomic Absorp- tion Spectrometry-L. Ebdon and E. Hywel Evans Comparison of Interferences and Matrix Modifiers in the Determination of Gold by Electrothermal Atomisation Atomic Absorption Spectrometry with Zeeman- effect Background Correction- J. Egila, D. Littlejohn, (the late) J. M. Ottaway and Shan Xiao-quan Direct Determination of Gold in Whole Blood and Plasma by Electrothermal Atomisation Atomic Absorption Spec- trometry Using Zeeman-effect Back- ground Correction and Matrix Modifica- tions-Shan Xiao-quan, J. Egila, D. Lit- tlejohn and (the late) J. M. Ottaway Removal of Phosphate and Silicate Inter- ferences in the Determination of Magne- sium, Calcium and Strontium by Atomic Absorption Spectrometry-M. M. El- Defrawy, M. E. Khalifa, A. M. Abdallah and M. A. Akl Atomic Spectrometry Update The Update in the April issue is-Clinical and Biological Materials, Foods and Beverages-Alistair A. Brown, David J. Halls and Andrew Taylor

ISSN:0267-9477    

DOI:10.1039/JA9870200012

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 13 Langmuir Probe Potential Measurements in the Plasma and their Correlation with Mass Spectral Characteristics in Inductively Coupled Plasma Mass Spectrometry Alan L. Gray Department of Chemistry, University of Surrey, Guildford, Surrey GU2 5XH, UK R. S. Houk Ames Laboratory-US Department of Energy and Department of Chemistry, lowa State University, Ames, /A 5001 7, USA John G. Williams Department of Chemistry, University of Surrey, Guildford, Surrey GU2 5XH, UK A floating Langmuir probe is used to measure the apparent d.c. potential in an inductively coupled plasma (ICP) while the latter is used as an ion source for mass spectrometry (MS). The probe is swung through the plasma to provide potential measurements with some spatial resolution and to obviate cooling of the probe.The d.c. potential in the centre of the plasma is influenced by the presence of the metal sampling cone in the plasma and also by the gas flow through the orifice. In general, the potential correlates with the characteristics of the mass spectra; these parameters depend in a sensitive fashion upon the manner by which the load coil is grounded and shielded. For the load coil geometries investigated in this study, the potential and ion energies generally increase with aerosol gas flow-rate and decrease as power increases. As potential increases the abundance of doubly charged ions generally increases, ArO+/Co+ and Ar2+/Co+ decrease and CeO+ decreases slightly. The measured potential in front of the sampling orifice is generally a few volts below the mean ion energy, which indicates that both measurements are reasonable approximations to the actual d.c. plasma potential.Keywords: Inductively coupled plasma mass spectrometry; ion sampling processes The analytical performance of ICP-MS is critically dependent on the ion extraction process. A crucial step in the develop- ment of ICP-MS into a useful analytical technique was the empirical study of the plasma - sampling cone interaction172 and the establishment of practical means of controlling r.f. potentials in the plasma, any resulting discharges to the grounded sampling cone and r.f. interference in the counting and control circuits. The load coil normally used to sustain an ICP for emission spectrometry has the downstream (top) end at high potential and the upstream (bottom) end grounded.A basic approach to reduce the r.f. potentials between the plasma and the sampling cone is to modify the load coil and its grounding arrangements. Initially this simply involved grounding the downstream end of the coil and this has been used by Gray,l Gray and Date,2 Olivares and Ho~k39~ and in the PlasmaQuad device marketed by VG Isotopes, An effective load coil configuration that reduces the r.f. potentials in the plasma to very low levels has been described by Douglas and French5 and incorporated into the Sciex Elan ICP-MS device. High voltage from the impedence matching network is applied to both ends of the coil and a ground strap is connected to a point equidistant from either end.Douglas and French report that this configuration also improves various other performance figures such as orifice lifetime and mass spectrometric peak shapes. More recently Grays has reported the use of other coil configurations which, although still grounded at one end, greatly reduce the r.f. potentials in the plasma by the geometrical disposition of the turns of the coil and by the use of a grounded screen between the coil and the plasma. Measurements of ion kinetic energy and other mass spectrometric parameters indicate that the plasma potentials obtained with the simple reversed load coil are higher than those from either the modified but asymmetrically grounded coils or from the centre tapped coil and that with all the asymmetrically grounded coils these potentials are more dependent on plasma operating parameters than with the centre tapped load ~0i1.4~6-8 Nevertheless, proper adjustment of operating conditions yields good analytical performance from all of these systems.This paper describes a way of experimentally estimating the apparent plasma potential directly and shows that the results of such measurements correlate with the mass spectral characteristics for the simple reversed load coil geometry. Experimental Potential Measurements The apparatus used to estimate plasma potential is shown in Fig. 1. It consisted of a W rod (1 mm diameter) which was allowed to swing through the plasma on a PTFE pivot. The tip of the rod protruded from a quartz sheath so that a short section 1 mm long was exposed to the plasma.A single swing of the probe took ca. 0.2 s; thus external cooling of the probe was not necessary because it was not exposed to the plasma long enough to cause melting or formation of an appreciable oxide coating. The probe path was positioned to traverse the centre of the plasma between the torch end and sampling orifice as shown in Fig. 1. The probe was connected via coaxial cables and a voltage divider (X 9) to the vertical input (impedance 1 MO) of a storage oscilloscope. A simple switch triggered one sweep of the oscilloscope when the probe was released. The resulting trace was a record of potential sensed by the probe as a function of position along the probe path through the plasma. This profile was then traced by hand to yield the potential profiles shown below.Langmuir probes are generally used to measure the electron temperature and density in a plasma, which requires determi- nation of probe current as a function of externally applied voltage.9 In the experiments described herein no external bias voltage was applied to the probe; the probe therefore sensed only the potential induced upon it by its contact with the plasma. Previous work by Douglas and French reported theJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 F I .- c 0.89 E 2 0.82 F 2 0.75 $ 0.67 2 0.60 2 0.53 - - 0 - + u, - $? 14 ( a ) - - - - - - l-z;d** ICP To \ Probe scope To path PTFE ground arm 0 10 20rnrn u Shield? f':te STpler Induction region Load CAA Tokh 4 0 10 20 30mm Fig. 1. Scale diagrams of apparatus: (a) view down barre- of torc..showin probe, insulating sleeve and pivot, and probe path through ICP; (by side view of torch, probe path and sampling cone. The orifice diameters through and the spacing between the sampler and skimmer have been enlarged for clarity; actual values for these dimensions are listed in Table 1 peak to peak r.f. voltage in the plasma, whereas the present work reports d.c. potentials because the r.f. component was filtered out by the long time constant of the input circuit of the oscilloscope used. Measurements with a larger (2 mm diameter) hand-held probe at various spatial positions in the plasma yielded potentials of the same polarity and similar magnitude to those measured with the swung probe. This experiment was carried out to verify that the potentials measured were not critically dependent on probe size or the rate of travel of the probe through the plasma. The hand-held probe was also used to check the d.c.potential with r.f. power applied but the plasma unlit. No potential greater than 0.1 V was seen, confirming that the potentials measured were not due to r.f. pick-up. ICP-MS Instrumentation The essential components and performance of this device have been described previously.2 Standard operating conditions are listed in Table 1; these conditions are close to those preferred for multi-element analysis with this equipment when used with a coil similar to coil X (Fig. 2). This table shows standard operating parameters when values for particular operating conditions are not specified for the data presented below.Three slightly different configurations for the load coil and shielding were used; these are depicted in Fig. 2. Coil X (referred to as the strapped and shielded configuration) was used unless otherwise stated. These coil configurations were chosen because they correspond closely to those used in earlier publications describing ion kinetic energies and mass spectral characteristics with two different ICP-MS instru- ments,4?7 and it was considered desirable to determine whether the plasma potential measurements were consistent with this previous work. The present paper is not meant to be a comprehensive evaluation of the best possible load coil geometry for ICP-MS.5.6 The sample solution contained 1 mg 1-1 of Co, Ba and of Ce in 1% HN03 in distilled de-ionised water.Cobalt was chosen because it does not form appreciable doubly charged or oxide ions and is close in mlz to Ba2+ and Ce2+. Barium and cerium I 0 29 :Omm c b I 0 0 4 HV uooh - X Y 2 Fig. 2. Scale diagrams of load coils, shielding and grounding configurations used in uresent work. A, Plasma torch; B, load coil; C, quartz bonnet; D, high voltage (HV) end of load coil; E grounded end of coil; and F, front screen I 1 1 1 1 1 1 1 1 1 1 1 ~ 1 ~ ~ -8 -7 -6 -5 -4 -3 -2 - 1 0 1 2 3 4 5 6 Position of IRZ/mm from coil edge Fig. 3. Position of tip of initial radiation zone relative to downstream turn of load coil for various powers and aerosol gas flow-rates A, 1 .O; B, 1.2; C , 1.4; and D, 1.8 kW were chosen because barium has the lowest second ionisation energy and CeO+ is one of the more refractory oxide species observed in ICP-MS.Mass spectra were acquired for cu. 1 min by scanning repetitively from rnlz 50 to 180; the resulting spectra were summed and transferred from the multi-channel scaler to cassette tape. Regions of interest were later selected corresponding to various ionic species of interest (e.g., background, singly charged analyte, doubly charged analyte and analyte oxide ions) and the resulting net peak integrals determined. Ion kinetic energies were determined for Co+ with the mass analyser transmitting only mlz 59 by applying a retarding positive potential to the entrance lens to the rods; otherwise, this lens was normally grounded. The potential required to stop the Co+ beam (denoted V,,, below) was taken as the applied voltage necessary to attenuate the Co+ signal to 0.1% of its original value for the particular set of parameters selected. This measurement method yielded similar trends to those reported by Olivares and Houk on their ICP-MS device except that the V,,, values determined in the present work tended to be somewhat higher.4 The position of the sampling orifice with respect to the load coil was left constant for most of the experiments reported herein.However, aerosol gas flow-rate and forward power to the plasma were varied over wide ranges so that the effective sampling position relative to the initial radiation zone (IRZ) varied between experiments.11 Therefore, the position of the downstream tip of the IRZ was determined visually during nebulisation of 1000 mg 1-1 of Y for various plasma operating parameters. The results are depicted in Fig.3 so that the changes in the spatial structure of the plasma during the experiments described below can be followed. The sampling orifice was downstream from the IRZ for all the powers and aerosol gas flow-rates used. Ion lens parameters were not fully re-optimised as would be done for analytical use after eachJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 15 Table 1. Standard operating conditions PowerIkW . . . . . . . . 1.2 Torch . , . . . . . . Standard length Fassel typelo Outer Ar gas flow-rate/ Auxiliary Ar gas flow-;aie/ Nebuliser . , . . . . . . Jarrel- Ash cross-flow Aerosol gas flow-ratell min-1 0.53-0.60 Sampling orifice: lmin-1 .. . . 12 1 min-’ . . . . . . . . 0 single-pass spray chamber lo Position . . . . . . . . 12 mm from end of load coil on centre Holediametedmm . . . . 1.0 Conematerial . . . . Ni Position . . . . . . . . 6 mm behind sampler on centre Holediametedmm . . . . 1.0 Skimmer: parameter change, so that absolute values of the Co+ signal did not represent optimised performance at each plasma parameter setting. However, the analytical significance of polyatomic ions such as ArO+ and Ar2+ lies in their relative size in relation to analyte reponse so these values are quoted as a ratio to the Co+ response. Results and Discussion Interpretation of Probe Potential Measurements Typical potential profiles obtained with load coil configura- tion X (Fig. 2) are illustrated in Fig.4. The approximate outer limits of the luminous white section of the plasma are also illustrated on the figure. In general the potential profiles showed three maxima across the plasma. The outermost potential maxima were just outside the plasma boundary. The farthest right maximum was slightly closer to the centre than the farthest left maximum because the probe velocity naturally increased during its travel down through the plasma. The structure on the farthest left maxima was not reproducible and thus is probably just noise. Most of the potential profiles had a sharp central maximum such as that depicted in Fig. 4. The actual potential at this position is denoted V, (where c denotes the centre) and is measured relative to ground because the sampling orifice is grounded.The observation that V, was generally of positive polarity and in the range 5-20 V agrees qualitatively with ion kinetic energies measured previously with the reversed load coil ge0metry.4~7.8 The probe revealed a plasma “warm-up” effect in that it took ca. 30 min for the potential profiles to stabilise after the plasma had been started and positioned in contact with the sampler. No such time lag was observed for a simple change of plasma parameters after this initial warm-up period, however. The trends of V, and profile shape with plasma parameters were quite reproducible although the magnitude of the V, values measured was reproducible only to within k 30% from day to day. It should also be noted that an isolated probe immersed in a plasma will assume a potential that is less than the actual plasma potential.The magnitude of this potential difference (often called the floating potential) depends upon the extent of electron cooling and ion - electron recombination in the vicinity of the probe. These effects are difficult to estimate accurately for probe measurements with an ICP. However, the floating potential could be of the order of several kT, (k = Boltzmann constant, T, = electron temperature in the unperturbed plasma near the probe), i.e., a few eV.12-14 The potential measurements reported below underestimate the actual plasma potential by up to this amount. Despite this offset in the absolute potentials, the measured potentials still illustrate the trends in actual plasma potential with plasma parameters, coil geometry, etc.Table 2. V, values (volts) measured for various plasma configurations, power 1.2 kW, coil to aperture spacing 12 mm Gas No gas extraction extraction Aerosol 1 min-1 Dry* vapourt aerosol$ gas flow-rate/ H20 H2O H2O aerosol - - - 0 34 0.53 33 34 27 8 0.60 32 32 25 10 0.67 33 31 23 12 0.75 34 29 22 16 0.82 34 27 21 18 0.89 33 25 20 18 * No H20 introduced. t HzO vapour introduced from residual H20 in spray chamber. 5 HzO aerosol introduced. 20 10 0 20 - ? : l o m .- +- CI 0 a 0 20 i a 0 (13) (12) 0 Probe position - Fig. 4. Measured potential profiles for coil X at 1.2 kW forward power and aerosol gas-flow rates of: (a) 0.75; (b) 0.60; and (c) 0.53 1 min-1. The central potential (V,) and the approximate outer boundaries of the ICP are indicated.Position 0 indicates the centre of the ICP Effects of Ion Sampling Conditions on Potential Measurements Potential profiles were obtained for a variety of plasma conditions that deviate from normal analytical application. Nevertheless, some interesting observations were made that pertain to the general objectives of this study. High negative potentials (ca. -50 V) were observed with the plasma on but separated from the sampler by ca. 0.5 m. In this situation the plasma was not in contact with a grounded object, the probe being isolated by 10 MQ. Formation of the space charge sheath around the floating probe caused the probe to assume a net negative potential.12-14 The polarity and magnitude of the potentials changed when the plasma was positioned in contact with the sampling orifice, for reasons to be described below.The V, values measured at the normal operating power level of 1.2 kW are shown in Table 2. The values obtained with the expansion stage pump shut off, so that no gas was extracted, are shown in the three columns under “No gas extraction.” When the plasma was unpunched, i.e., with no aerosol gas flow, the measured V, was 34 V. Punching the central channel through the plasma with a flow of dry argon at flow-rates from 0.53 to 0.89 1 min-1 made no significant difference to V,. The16 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 introduction of water vapour obtained by passing the aerosol gas through the nebuliser spray chamber without water uptake (column “HzO vapour”) made no difference to the potential at low gas flow-rates but as the flow-rate increased and more vapour was taken up from the water surface in the spray chamber the potential steadily decreased.The introduction of still more water by operating the nebuliser uptake pump, so that aerosol droplets were introduced as well as vapour, resulted in still lower potentials, down to 20 V at 0.89 1 min-1. Under these “extractionless” conditions the boundary layer over the surface of the sampling cone remained unbroken. As soon as the expansion stage pump was started, however, the boundary layer over the aperture was broken, and the potential became very much lower. Although not shown in Table 2 the potential observed when the plasma was unpunched during ion extraction was ca.+2 V. When the axial channel was punched with dry argon the potential rose to ca. 4 V. When water was added as nebulised aerosol the potential increased with flow as shown in the final column, i. e., the opposite trend to that seen under “extractionless” conditions. This marked difference in behaviour when ions were extracted was thought to be due to the much closer contact between the plasma and the cone once the boundary layer over the aperture had been penetrated. The complete boundary layer (ie., with the pump off) formed a relatively high impedence between the plasma and grounded cone, which was affected by the amount of water introduced, possibly due to the higher electron density from ionised H and 0.15 When the plasma was drawn through the aperture it was only separated from the cone by a much thinner boundary layer along the inner surfaces of the orifice superimposed on the very thin plasma sheath.16 Therefore, a much lower potential developed across the thinner boundary layer because the impedance to the flow of charged particles was lower.It is the presence of this sheath that produces the positive d.c. offset potential (relative to the grounded cone) from the r.f. potentials in the plasma,l2 the differing mobilities of ions and electrons causing the sheath to behave partly as a rectifying layer. Behaviour similar to this has already been reported from the ion energy measurements.8 Conditions in the sheath region may be expected to depend critically on plasma parameters such as temperature and electron density, which are themselves determined by aerosol gas flow-rate and composition, plasma power, etc., and geometrical considera- tions such as coil configuration, plasma coil - aperture spacing and aperture diameter.The above hypothesis is only intended to provide a qualitative picture of the ion extraction process. A precise description of these phenomena involving time varying electric fields, fluid effects, spatial gradients of temperature and compositions, etc. is a very challenging objective. A useful discussion of the behaviour of plasma sheaths in the presence of high frequency r.f. potentials has been given by Chapman. 12 Potential and Mass Spectrometric Measurements Under Analytical Operating Conditions Numerous potential profiles (Figs. 4-7) and mass spectra (Table 3) were obtained for a range of plasma operating conditions spanning those of use for actual analysis with this particular device (Table 1) except that the coil - aperture spacing was 15 mm.Mass spectra (but not potential profiles) were obtained with this load coil at a spacing of 12 mm; the trends of Ba2+/Co+, etc. with power and aerosol gas flow-rate were similar to those shown in Table 3. For all the tables in this paper the ratio Cez+/Co+ was also determined; this ratio was always smaller than Ba2+/Co+ and followed the same trends with power and flow-rate. Inspection of the data in Table 3 yielded the following general trends with some exceptions as V C "pel t 4 l o t (6) y o y 0 Probe position - Fig. 5. Potential profiles at low aerosol gas flow-rate (0.53 1 min-I), coil X: (a) 1.4; (b) 1.6; and (c) 1.8 kW.Compare with Table 3 20 0 - Probe position - Fig. 6. Potential profiles for coil x at 0.75 1 min-1 aerosol gas flow-rate and powers: of (a) 1.0; (b) 1.2; (c) 1.4; and (d) 1.6 kW. Compare with Table 3 Probe position - Fig. 7. Potential rofiles for coil X at 0.89 1 min-l aerosol gas flow-rate: (a) 1.2; (g) 1.4; and (c) 1.6 kW. Compare with Table 3JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 17 Table 3. Measured potential values compared with mass spectral characteristics for various plasma operating parameters. The sampling orifice was 15 mm from the load coil (X) for this data Aerosol/ 1 min-1 Power/kW 0.53 1 .o 1.2 1.4 1.6 1.8 0.60 1 .o 1.2 1.4 1.6 0.75 1.0 1.2 1.4 1.6 0.89 1 .o 1.2 1.4 1.6 V,N* 13 11 10 8 6 17 13 10 8 16 18 10 8 13 13 14 9 vmax/v-t 25.8 25.6 19.6 19.1 18.1 29.3 25.8 23.8 19.9 38.2 30.7 28.1 23.7 38.8 38.5 32.8 28.2 B aZ+/Co + , ratio, YO 1.40 0.50 0.41 0.50 0.84 5.40 0.64 0.34 0.57 50.3 5.6 0.66 0.46 82.0 48.0 9.3 1.9 * Uncertainties typically hl V.t Uncertainties typically k0.5 V. $ ArO+ monitored at rnlz 56 and Ar2+ at rnlz 80 for this and subsequent tables. CeO+/Ce+, ratio, % 0.69 0.99 1.30 1.70 2.10 0.55 0.85 1 S O 1.60 0.91 0.78 0.85 1.20 1 .oo 0.95 0.94 1 .oo ArO+/Co+, ratio, %$ 22 35 68 96 135 13 19 53 68 4.2 7 1.2 21 4.5 3.5 5.2 11 Ar,+/Co+, ratio, O/O$ 479 505 221 189 139 173 334 461 194 24 97 91 290 16 14 47 97 noted. For the same operating conditions the V, values listed on the figures do not always agree exactly with those in Table 3 because the latter were averaged over several swings of the probe, whereas the figures were traced after only one swing.Increasing the aerosol gas flow-rate at constant power induced either an increase or no appreciable change in V, (e.g., Fig. 4) except at low power and high aerosol gas flow-rate. Increasing the power at constant aerosol gas flow-rate generally induced a decrease in V, except at low power and high aerosol gas flow-rate (e.g., 1.0 kW and 0.75 1 min-1, Table 4, Figs. 6 and 7). In the last instance the valleys in the potential profiles (marked by the arrows in Figs. 6 and 7) were elevated considerably further above ground than under other operating conditions. In contrast, use of high power and low aerosol gas flow-rate suppressed these valley potentials (see arrows, Figs.5 and 6) to small positive or even negative values, which tended to pull V, down also. Increasing aerosol gas flow-rate andor decreasing power caused V,,, and Ba2+/Co+ to increase. The ratio CeO+/Ce+ increased with the aerosol gas flow-rate at low power (Table 3), decreased as aerosol gas flow-rate increased at high power, and generally increased with power at constant aerosol gas flow-rate. In other words, changing a plasma parameter that caused an increase in V, generally induced a corresponding increase in ion energies and doubly charged ion abundances and a small decrease in metal oxide abundances. The behaviour described above is consistent with the following interpretation. The majority of the gas species in the centre channel of the plasma that enter the aperture are neutral (ca.99.9%) and acquire an energy from the supersonic expansion of about 1.5 eV.17 A relatively small proportion (ca. 0.1 %) of the total species are charged with equal numbers of positive ions and electrons present. The potential plots obtained with the probe show the potential to have a maximum at the centre of the plasma, the size of which depends on the plasma operating parameters. Relative to the grounded sampling orifice, the ions and electrons generated in the plasma appear to originate from a region at this potential and thus ions enter the aperture with a kinetic energy greater than that of the neutrals. At the higher plasma potentials, the d.c. and r.f. fields in the region of the plasma sheath at the aperture contribute to the electron energy so that excited states are populated and decay to produce a visible glow inside the expansion chamber when water is introduced into the central channel.At higher energies still, for V, values of ca. 13 V and above, additional double ionisation is produced in species such as Ba with low second ionisation energies. The extent of this does not appear to correlate with V, values above 13 V but does increase with Vmax above a threshold at ca. 28 V. At the flow-rates (0.53 and 0.6 1 min-1) and power (1.2 kW) normally used for analysis with this coil, values for V,, V,,,, Ba2+/Co+ and CeO+/Ce+ are close to the lowest obtained. As reported previously, the trends of Baz+/Co+ and CeO+/Ce+ with power and flow-rate were opposite to those expected from the ICP al0ne.18~19 This behaviour indicates that the potential difference between the plasma and the orifice could be responsible for helping to keep oxide ions dissociated during the extraction process.However, Table 3 shows that ( a ) there is only a factor of 2-3 to be gained in reducing CeO+/Ce+ by deliberately inducing a high plasma potential, (b) at low power, increasing the aerosol gas flow-rate actually makes CeO+/Ce+ less favourable and ( c ) deliberate elevation of the plasma potential to overly high values would make doubly charged ions more of a problem. The interpretation of the effect of power and aerosol gas flow-rate on the polyatomic (cluster) ion levels is superficially more straightforward. Both ArO+/Co+ and Ar2+/Co+ dec- rease consistently with increasing aerosol flow, suggesting that the increased energy available at higher plasma potentials does produce dissociation.These species are probably formed behind the aperture and are relatively weakly bound. They may be expected to show the highest cross-sections for their formation reactions at low ion energies, so the response may merely reflect the probability of their formation in the supersonic expansion. This behaviour may also simply reflect changes in the abundance of the atomic precursor ion (e.g., O+ for ArO+, Ar+ for Arz+) in the plasma with operating conditions, i.e., reduction of the O+ concentration in the plasma means there is less O+ available to react with neutral Ar during the expansion, so less ArO+ is detected.Apart from a few instances at the lowest values of V, obtained with this coil, and which are insufficiently general to carry much weight, the trends reported are generally consis- tent with those reported previously for load coils that are asymmetrically grounded,6?7 and opposite to those reported for the centre tapped load coil with which the behaviour of doubly charged, oxide and cluster ions tends to follow what would be expected from the ICP itself.lg.19 With the centre tapped coil, ion energy is almost independent of plasma18 10 5 - 0 -5 ? .- c(1 - 1 0 - - c JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 - ( a ) - (C) (8) (5) V t - t I ( 4 0 2l Probe position - Fig. 8. Potential profiles for coil X, 1.0 kW: (a) no aerosol gas flow; and dry Ar only in aerosol gas flow at (b) 0.53 and (c) 0.60 1 min-1 operating parameters.In spite of this apparent advantage the analytical performance of ICP-MS systems with either type of load coil has been shown to be similarly dependent on plasma operating parameters, especially aerosol carrier gas flow- rate.3.7.18 The real significance of this dependence however lies in the variations experienced by a user in operating the system when plasma parameters are nominally stabilised and this appears to depend more on other aspects of system engineering than on the specific load coil geometry involved. Effects of Water Content on Probe Potential Measurements Additional potential profiles were obtained while gas was extracted through the orifice from ICPs with no axial channel and with dry Ar rather than Ar plus nebulised H20 injected into the axial channel.Typical results are depicted in Fig. 8 and V, values are shown in Table 2. In the absence of aerosol gas flow the measured potential in the centre of the ICP was very low; punching the axial channel with dry Ar induced an increase in V,. These two observations are in agreement with those reported previously for one of the Ames instruments4 and for the Surrey instrument used here.8 However, compari- son of the potential profiles and V, data in Fig. 8 with those for injection of wet aerosol (e.g., Fig. 5 and the right-hand column of Table 2) indicate that introduction of water while gas was being extracted caused V, to increase sharply compared with that obtained when only dry Ar was injected into the axial channel.This behaviour has also been reported previously.8 As noted above, the opposite trend was observed when there was no gas flow through the orifice. It is also interesting that the injection of water into the axial channel raised the voltage signal outside this region of the plasma. In other words, the potentials measured in the valleys of the profiles (marked by arrows in Fig. 8) were affected by the presence or absence of H20 in the axial channel. It would seem that the injected H20 plays an active role in determining the over-all chemical and even electrical characteristics of the ICP when the latter is used as an ion source. Effects of Shielding Experiments such as those described above were also perfor- med using the same load coil but a larger aperture in the shielding box (Y, Fig.2). Typical results are depicted in Figs. 9-11 and Table 4. For these data the sampling orifice was slightly closer to the load coil (12 mm) than for those shown in Table 3. Because the mass spectral characteristics were also influenced by the ion sampling position, the absolute values in Table 3 are not strictly comparable to those in Table 4. The discussion below thus emphasises the trends of V, with V,,, 10 5 0 -5 -10 ? 10 .- 2 5 - Q, a 5 0 -5 -10 10 5 0 -5 -10 t Probe position - Fig. 9. Potential profiles for coil Y at 1.2 kW and aerosol gas flow-rates of: (a) 0.53; (b) 0.60; and (c) 0.67 1 min-1. Compare with Table 4. Arrows mark region of apparent negative potential h $21 10 5 0 -5 c v c t I 5 t I Probe position - Fig.10. Potential profiles for coil Y, 1.6 kW for aerosol gas flow-rates of: (a) 0.6; (b) 0.67; (c) 0.75; (d) 0.82; and (e) 0.89 1 min-1. Compare with Table 4 -5 ? - ru .- .I-- != '0 n .I- 0 5 -10' I Probe position - Fig. 11. Potential rofiles for coil Y at 0.89 1 min-1, dry Ar only in aerosol gas flow: (nf1.2; and (b) 1.6 kWJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 19 ~~ ~ Table 4. Measured potential values and mass spectral characteristics for less shielded load coil (Y), sampling position 12 mm Aerosol gas flow-rate/ Power/ Ba2+ /Co + CeO +lCe + ArO + /Co + Ar2+ /Co + 1 min-1 k W vfl V,,,N ratio, Yo ratio, Yo ratio, % ratio, YO 0.53 1.0 1.2 1.6 1.6 0.67 1 .o 1.2 1.4 1.6 8 f l 6 6 t 67 11 10 7 7 19.2 k 0.5 16.7 21.8 18.4 26.0 22.3 18.6 17.2 0.1* 0.1* 0.91 0.87 1.1 0.3 0.03* 0.09* 1.5 1.7 2.4 2.1 0.9 1.4 2.0 2.3 8.4 8.3 60 69 2.4 3.2 6.7 7.7 226 46 54 105 66 132 138 27 0.75 1.2 10 25.4 1.1 1.1 2.2 55 1.6 8 20.8 O* 1.5 3.5 52 1.4 8 24.1 0.2* 1.4 3.8 68 0.89 1.4 12 28.0 1.9 1.1 1.1 14 1.6 12 25.2 1.1 1.3 1.8 23 1.8 12 25.0 0.8 1.5 3.2 50 1.8 127 24.3 0.4 1.4 2.7 31 1.6 121.25.2 0.8 1.2 1.4 22 * Ba2+ levels under these conditions were comparable to or smaller than the background, so the Ba2+/Co+ values listed are only t Results of dudicate trials when indicated power and flow-rate were reset after ca. 30 min interval. approximations. and how these reflect changes in mass spectral characteristics with power and flow-rate. As shown in Figs.9-11, the potential profiles were less symmetrical for the less shielded coil (geometry Y). This was particularly so for the initial valley (marked by arrows in Figs. 9 and lo), which even assumed a negative polarity under conditions of low aerosol gas flow-rate and high power. Increasing aerosol gas flow-rate at constant power displaced this valley to more positive potentials with corresponding increases in V,, V,, and Ba2+/Co+. In Table 4 the general trends in ArO+/Co+ and Ar2+/Co+ with changing power and aerosol gas flow-rate are also similar to those in Table 3. Thus, changing a plasma parameter that altered Vc also changed the characteristics of the mass spectra in ways similar to those seen with coil X. Although the precise cause of the negative valley is not certain, its effect was to reduce the potential difference between the centre of the plasma and the sampling orifice and apparently attenuate the influence of this potential difference on the mass spectra. Several sets of data obtained separately under the same operating conditions are also listed in Table 4; these illustrate the typical reproducibility of these parameters during a single day’s operation.It is very interesting that less extensive shielding of the load coil (geometry Y) should yield unsymmetrical potential profiles and lower plasma potentials and ion energies than a closely screened coil (geometry X). The following two observations with load coil Y also merit discussion. The probe dropped vertically close to the down- stream turn of the load coil, which was connected to the ground at its bottom end (Fig. 1).For the profiles shown in Figs. 9-11 the top side of the coil [marked in Fig. l(a)] floated at higher potential than the bottom side, the latter being closer to the ground strap. The negative valleys in Figs. 9-11 appeared when the probe had just entered the ICP. In other words, the plasma region where negative potentials were apparently developed was adjacent to the load coil section at higher applied r.f. potentials. To test this explanation a load coil of similar dimensions but with the direction of the windings reversed was then substituted so that the higher voltage side of the coil was below centre. The negative valley in the potential profiles now occurred below the centre, i. e., it followed the high voltage side of the coil.Finally, some potential profiles obtained at high aerosol gas flow-rate with only dry Ar injected are shown in Fig. 11. These profiles showed pronounced negative valleys and very small values of V, (2-3 V). Thus the exclusion of H20 yielded lower plasma potentials with either the tightly shielded or loosely shielded load coil. This observation concurs with the general experience in Surrey and Ames that introduction of sample without concomitant H20 yields lower ion energies.20 Effects of Grounding The data described up to this point were obtained with a short copper braid connected from the downstream turn of the load coil to the grounded shielding box. Numerous spectra and potential profiles were also obtained with a load coil grounded only at the coupling box (configuration Z , Fig.2); the results are summarised in Table 5. Comparison of these data with Table 4 indicates that higher levels of V,, Vmax and Ba2+ were generated with the ground strap removed and the diameter of the shielding aperture held constant. This agrees with other observations that grounding the load coil with an additional strap helps to diminish the plasma potential.5 The potential profiles still had negative valleys at high power and low aerosol gas flow-rate, although these valleys were less pronounced than for load coil Y. The trends of V, and mass spectral characteristics with changing aerosol gas flow-rate and power were similar to those seen with the other load coils, except that the ratio CeO+/Ce+ was largely independent of plasma operating conditions with the ground strap absent. It is also interesting that load coil Z at 0.89 1 min-1 yielded levels of Ba2+ comparable to or even slightly less than those obtained with load coil X even though the former lacked a ground strap.Thus, the plasma potential and the characteristics of the mass spectra depend in a sensitive fashion upon the grounding and shielding of the load coil. Nevertheless, careful adjustment and control of operating parameters can yield good analytical performance with various versions of the reversed load coil. Comparison of Plasma Potential with Ion Kinetic Energy It is interesting to note that V, was generally much less than V,, for Co+. However, if V, represented the actual plasma potential, it should have been comparable to the mean ion energy E , which was approximately 4ym,. Inspection of Tables 3-5 shows that in most instances E was higher than Vc by +1 to +4 V; in a few instances ( E - V,) was slightly negative or as high as +10 V.?ere are at least two phenomena that could have caused E to be a few volts above V,. First, as pointed out by Fulford and Douglas, the ions20 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 Table 5. Potential values and mass spectral data for unstrapped, less shielded load coil (Z). Sampling position 12 mm above load coil Aerosol gas flow-rate/ 1 min-1 0.53 0.60 0.67 0.75 0.89 Power/ kW 1 .o 1.2 1.4 1.6 1.8 1 .o 1.2 1.4 1.6 1.8 1.0 1.2 1.4 1.6 1.8 1.0 1.2 1.4 1.6 1.8 1.0 1.2 1.4 1.6 1.8 v f l 1 3 f 1 11 9 9 9 15 12 9 10 9 16 14 11 11 10 15 16 13 12 11 13 16 17 16 14 VmaxN 35.0 f 0.5 31.0 29.3 25.4 23.5 39.4 34.5 30.6 29.6 26.8 43.7 37.4 35.6 31.5 30.2 45.8 40.8 37.5 34.9 32.3 46.9 47.9 45.9 41.2 37.4 Ba2+/Co+ ratio, YO 5.8 0.2 O* O* O* 2.6 O* O* O* 9.3 2.7 O* O* 20 32 31 20 8.7 1.8 0.2* 30 38 29 15 8.6 CeO +/Ce+ ratio, Yo 0.7 0.7 0.7 0.8 1.2 0.5 0.8 0.8 0.8 0.9 0.3 0.6 0.8 1 .o 0.9 0.6 0.7 0.8 1.1 1.1 0.4* 0.6 0.8 0.8 0.9 ArO +/Co+ ratio, YO 5.8 9.5 6.0 4.8 4.7 2.6 5.9 6.0 5.5 7.3 1.9 3.8 3.4 5.2 7.8 1.8 1.7 2.1 3.6 7.0 1.4 0.9 1 .o 1.5 5.9 Ar2+/Co+ ratio, YO 200 150 135 87 54 65 169 160 150 144 7 100 140 161 207 4 18 92 100 107 2.0 2.0 2.6 17 73 * Ba2+ or CeO+ levels under these conditions were comparable to or less than the background, so the ratios listed are only approximations. acquire kinetic energy by being entrained in the Ar flow in the supersonic jet.For Co+ this contribution amounts to ca. 1.5 eV.17 The second source of voltage offset is the floating potential effect described above. The magnitude of this effect tends to increase with the flow velocity of gas in the plasma,13 which could partly explain why V, tended to level off or even decrease at high aerosol gas flow-rate while V,, continued to increase. Incorporation of the floating potential and the energy acquired by the ions during the sup_ersonic expansion brings V, into approximate agreement with E, i.e., the average ion energy is comparable to the plasma potential. The work at Surrey was supported jointly by the British Geological Survey (NERC) and the Directorate General for Science, Research and Development (DG XIUG-2) of the European Community. J.G. W. acknowledges support from the Procurement Executive, Ministry of Defence, UK. R. S. H. was supported by the Ames Laboratory-US Department of Energy, Contract No. W-7405-Eng-82 via the Director for Energy Research, Office of Basic Energy Sciences. R. S. H. also acknowledges travel support provided by VG Isotopes. References 1. Gray, A. L., Ph.D. Thesis, University of Surrey, 1982. 2. Gray, A. L., and Date, A. R., Analyst, 1983, 108, 1033. 3. Olivares, J. A., and Houk, R. S., Anal. Chem., 1985,57,2674. 4. Olivares, J. A., and Houk, R. S., Appl. Spectrosc., 1985,39, 1070. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. Douglas, D. J., and French, J. B., Spectrochim. Acta, Part B, 1986,41, 197. Gray, A. L., J. Anal. At. Spectrom., 1986, 1, 247. Gray, A. L., Spectrochim. Acta, Part B, 1986,41, 151. Gray, A. L., Fresenius 2. Anal. Chem., 1986,324,561. Smy, P. R., Adv. Phys., 1976, 5,517. Scott, R. H., Fassel, V. A., Kniseley, R. N., andNixon, D. E., Anal. Chem., 1974,46,75. Koirtyohann, S . R., Jones, J. S., and Yates, D. A., Anal. Chem., 1980, 52, 1965. Chapman, B., “Glow Discharge Processes,” Wiley, New York, 1980, Chapters 3 and 5. Clements, R. M., and Smy, P. R., J. Phys. D, Appl. Phys., 1974, 7 , 551. Swift, J. D., and Schwar, M. J. R., ‘‘Electrical Probes for Plasma Diagnostics,” Iliffe Books, London, 1969, Chapters 1,7 and 12. Alder, J. F., Bornbelka, R. M., and Kirkbright, G. F., Spectrochim. Acta, Part B, 1980,35, 163. Houk, R. S., Fassel, V. A., and Svec, H. J., Dynamic Mass Spectrom., 1981,6, 234. Fulford, J. E., and Douglas, D. J., Appl. Spectrosc., 1986,40, 971. Horlick, G., Tan, S. H., Vaughan, M. A., and Rose, C. A., Spectrochim. Acta, Part B, 1985,40, 1555. Vaughan, M. A., and Horlick, G., Appl. Spectrosc., 1986,40, 434. Jiang, S.-J., and Houk, R. S., Anal. Chem., 1986, 58, 1739. Paper J6170 Received August 4th, 1986 Accepted October 22nd, 1986

ISSN:0267-9477    

DOI:10.1039/JA9870200013

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 21 Effect of Torch Size on a 148-MHz Inductively Coupled Plasma Bryan D. Webb* and M. Bonner Denton Department of Chemistry, Faculty of Natural Sciences, University of Arizona, Tucson, A2 84721, USA Physical parameters and analytical performance are presented for three analytical lCPs operated at 148 MHz. The torch size has been varied in these three systems in order to investigate more closely the influence of the ratio of plasma radius ( r ) to skin depth (s) on the plasma characteristics. The electron number density appears to be directly related to the r/s ratio, while the excitation temperatures and ion to atom intensity ratios only follow a general trend. A 10 mm i.d. torch a t 148 MHz provides conditions most similar to a standard 18 mm i.d.torch at 27 MHz. An intermediate-size torch of 13 mm i.d. provides a good balance between the increased ease of sample handling of a large r/s ratio torch and the improved sensitivity of a small r/s ratio system. The r/s ratio is shown to be a convenient means of understanding the effects of changes in the plasma operating frequency and in the torch size. Keywords: Inductively coupled plasma; torch size; plasma characteristics When investigating the effect of torch size on inductively coupled plasma (ICP) operating characteristics, it is useful to think of the energy deposition region in terms of the skin depth, s. An electromagnetic field is induced in the discharge by the oscillating current flowing in the load coil.The skin depth is defined as the distance required for this induced field strength to fall off to l l e of its value at the surface. A previous investigation into plasma characteristics1 studied the effect of decreasing the skin depth by increasing the operating fre- quency to 148 MHz, and electron density was found to change proportionally with skin depth at a fixed torch size. It was not clear from this study whether the skin depth alone or the ratio of plasma radius, r, to skin depth (r/s) was the controlling parameter. The ratio of plasma radius to skin depth may be adjusted at a fixed frequency by changing the torch size. An “optimum” rls ratio of 2.25 was stated in the literature,z which is approximately obtained with an 18 mm i.d. torch at 27 MHz. Several workers have investigated smaller torches at 27 MHz,3-5 which have a smaller r/s, but no electron densities were measured, and excitation temperatures were determined only at single observation heights .3,4 These observations appear to have been made in the normal analytical zone (NAZ) as defined by Koirtyohann and co-workers.697 The advantage of a larger rls ratio is increased ease of sample introduction, as the analyte, which is injected along the central channel of the plasma, is farther from the primary energy deposition region, and hence less perturbing of the energy deposition process.The disadvantage is a lower energy environment experienced by the analyte. Detection limits were found to degrade at the larger r/s ratio due to the lower energy environment, but organic samples were capable of being aspirated with no change in operating parameters.1 An intermediate rls ratio may be expected to provide a more optimum trade-off between sensitivity and sample handling ability. At a fixed frequency, the rls ratio may be reduced simply by reducing the torch size. The lower size limit is set where the analyte begins to interact with and perturb the energy deposition region. This paper describes the results of such an investigation, in which three different torch sizes have been evaluated at the operating frequency of 148 MHz. The physical parameters of excitation temperature, electron num- ber density and ion to atom line intensity ratios have been * Present address: Unocal Science and Technology Division, 376 South Valencia, Brea, CA 92621, USA. determined for the three torch systems used in this study.Analytical performance has also been evaluated in regard to signal to background ratios, detection limits, calibration graphs, interferences and ease of organic sample introduction. Apparatus and Techniques Instrumentation The 148-MHz generator, matching network and plasma diagnostic techniques have been described previously. 1 Two different demountable torch bases were used in this study with quartz tube sizes and gas flow-rates as shown in Table 1. These tubing sizes were not specifical!y optimised for operation at extremely low powers or gas flow-rates, but were selected from standard sizes for ease of construction. Reducing the diameter of the upper portions of the quartz tubing allowed the smallest “micro-torch” to share the same acrylic plastic torch base and PTFE tube spacers as the standard torch.8 The medium-size “midi-torch” was placed in a base constructed from stainless-steel Ultra-Torr fittings (Cajon Co., Macedo- nia, OH, USA), which were bored out to accept the metric size quartz tubing.The outer gas flow was adjusted in each torch to just keep the plasma off the walls of the outer tube at 1500-W forward power. The nebuliser gas flow was adjusted so that the tip of the initial radiation zone (IRZ) fell 15 mm above the load coil, so that similar plasma zones were observed at each observation height independent of torch size. Table 1. Torch dimensions (mm i.d. x mm 0.d.) Torch Tube Standard Midi Micro Outer- Upper . . . .. . 18 X 20.5 13 x 15 10 x 12 Lower . . . . . . 18 X 20.5 13 X 15 18 x 20.5 lmin-‘ . . . . . . 12.2 12.5 12.8 Upper . . . . . . 1 3 x 15 8 x 10 7 x 9 Lower . . . . . . l o x 12 6 x 8 10 x 12 1min-l . . . . . . 0 0 0 Opening . . . . 1.5mm l.Omm Lower . . . . . . 4 x 6 2 x 4 4 x 6 1min-l . . . . . . 0.7 0.6 0.5 Gas flow-rate/ Intermediate- Gas flow-rate/ Injector- l.Omm Upper . . . . . . 4 x 6 2 x 4 2 x 4 Gas flow-rate/22 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 z F I 4- 5000 C 0 m V u1 .- c 4- .- 4000 Skin Depths The skin depth, s, may be calculated from the equation s(mm) =50*3(aClv)-+ . . . . . . (1) where u is the specific electrical conductivity and p is the relative permeability of the absorbing medium, and Y is the frequency in MHz.2 The relative permeability of a gas can be taken as unity, and the dependence of CJ on temperature at atmospheric pressure is plotted as Fig.1 of reference 2. The actual argon temperature in the energy deposition region to be used in the estimation of u is unknown, but the value of u = 10 S2-1 cm-1 used by Scott et aZ.2 is consistent with the 7000-8000 K found by Uchida et aZ.9 The value of s = 3.1 mm calculated at 27 MHz scales to s = 1.3 mm at 148 MHz due to the change in frequency. Ratios of rls for the three different torches used in this study are 6.2 for the 18 mm i.d. standard torch, 4.6 for the 13 mm i.d. midi-torch and 3.5 for the 10 mm i.d. micro-torch. In contrast, the rls ratio for a standard size torch at 27 MHz is 2.7. - - Results and Discussion Excitation Temperatures Iron I excitation temperatures determined for the three different torches at three power levels at 148 MHz are shown in Fig.1. The highest temperatures are obtained in the 5000 - 2 E c Q ; c 4000 0 m V X UJ - .- c c .- 3000 I 10 20 30 smallest torch at the highest power, which is in agreement with an intuitive picture of the situation. A higher energy environ- ment prevails in the analyte channel when the torch size is decreased, because the analyte channel becomes closer to the energy deposition region. This is in contrast to previous results at 27 MHz, where lower temperatures were found in the NAZ as torch size was decreased.3.4 As rls was less than 2.25 for these torches, it may be reasonable to assume that the maximum temperature is obtained near the previously dis- cussed “optimum” rls = 2.25.2 A different vertical temperature profile is seen for each torch size.That of the largest torch is smoothly decreasing, while the smallest torch exhibits a maximum temperature ca. 20 mm above the load coil. This is 4-5 mm above the bottom of the NAZ. A similar vertical spatial behaviour was also seen for the standard size torch at 27 MHz.lJOJ1 The midi-torch provides the most uniform temperature environment over a range of observation heights. In Fig. 2, excitation temperatures are compared at three different observation heights for the range of rls ratios covered by this study. Values at 27 MHz are included from the previous work.1 The general trend of increasing temperature with decreasing rls can be seen, but a strict linear dependence is not maintained at all observation heights because of the different vertical temperature profiles of the three torch systems, The rls ratio does provide a means to account for the effects of changing both the torch size and the generator frequency.A B - C I I I I I 10 20 30 40 0 Observation heightim rn Fig. 1. B, midi- and C, standard-size torches Iron I excitation temperatures determined at 148 MHz for input powers of (a) 900, (b) 1200 and (c) 1500 W in the A, micro-, I (a’ 6ooo t 1 \ 1 I I I I I I 2 4 6 0 2 4 6 0 2 4 6 3000 0 Ratio of plasma radius to skin depth Fig. 2. Iron I excitation temperatures as a function of rls ratio for input powers of (a) 900, (b) 1200 and (c) 1500 W at observation heights of A, 13.0, B, 19.5 and C, 32.5 mm above the load coilJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL.2 23 I I I I Electron Number Densities like that seen earlier for the 27-MHz standard torch. The I I I I 1 I I Electron number densities determined from Stark broadening of the hydrogen HP line at 486.13 nm are presented in Fig. 3. For a given torch, the electron number density increases regularly with increasing power and decreases with observa- tion height. It is more interesting to plot electron densities as a function of the r/s ratio, as in Fig. 4. The electron number density was previously seen to be dependent on the skin depth at a fixed torch size.1 Here, it is more correctly seen to be dependent on the rls ratio. larger rls here seems to shift the position of maximum ion intensity higher in the plasma, which is consistent with the lower energy environment in the analyte channel in the larger torches.This is somewhat curious, however, because the IRZ visibly peaked 15 mm above the load coil for all three torches. The position of maximum ion intensity does not always seem to be correlated with the position of the IRZ. Increased power does not shift the position of the maximum ion to atom ratio, but does increase its value. Ion to Atom Intensity Ratios Fig. 5 shows magnesium ion (280.27 nm) to atom (285.21 nm) emission line intensity ratios determined for the three torches. Again the smallest torch exhibits a vertical spatial profile most Approach to Local Thermal Equilibrium The approach to local thermal equilibrium (LTE) can be estimated from the observed electron number densities and suitable ion to atom emission intensity ratios, (Z+/10).12J3 The Fig.3. B, midi- and C, standard-size torches Electron number densities determined from Stark broadening for input powers of (a) 900, (b) 1200 and (c) 1500 W in the A, micro-, Fig. 4. Electron number densities as a function of rls ratio for input powers of (a) 900, (b) 1200 and (c) 1500 W at observation heights of A, 13.0, B, 19.5 and C, 32.5 mm above the load coilJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 1 1 0 10 20 30 40 0 10 20 30 40 Observation heightimm 1 1 I I 10 20 30 40 Fig. 5. Magnesium ion A, micro-, B, midi- and nm) to atom (285.21 nm) emission intensity ratios for input powers of (a) 900, ( b ) 1200 and (c) 1500 W in the 0.30 2 0.20 >, 3 m 21 - 0.10 0 Fig.6. torches ( a ) //7r.\, /*- * - - 7 5 1 I I I I 1 I 1 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 bse rvat i on height/ m m Values of b, calculated for input powers of (a) 900, ( b ) 1200 and (c) 1500 W in the A, micro-, B, midi- and C, standard-size parameter b,, which indicates the deviation from LTE, is then obtained from Fig. 6 shows b, values calculated from the electron number densities and magnesium ion to atom intensity ratios for the three torches. As the electron number density falls off fairly smoothly with height, the vertical profile of the b, values closely resembles that of the magnesium intensity ratios. It should be noted that the theoretical basis for LTE here is the electron number density, rather than an excitation temperat- ure.Since excitation temperatures may be dependent on the element involved and the excitation energies of the levels used in the determination,14 the electron number density is felt to be a more suitable framework for LTE calculations.13 This leads to b, values of less than one, rather than of the order of 10-300. 1 5 7 1 6 An under population of ions compared with LTE predictions is indicated instead of an over population as has been generally stated. This is entirely due to the choice of LTE framework. The trend with the rls ratios shown in Fig. 7 is not as well defined as the electron number density dependence, but LTE is more closely approached in the NAZ as rls is decreased and as power is increased.This is consistent with the increased electron number densities and temperatures obtained under these conditions. Analytical Performance Signal to background ratios were determined for ten lines of seven elements at an observation height of 19.5 mm at 1200 W. Although several different concentrations and electrometer settings were employed, the results in Table 2 are all corrected to the same electrometer scale and equivalent concentration; detection limits are also included. A uniform increase in analytical performance is seen for all these elements when torch size is reduced, with a relatively greater increase for the ion emission lines compared with the atom lines. This behaviour is consistent with the increased temperature and electron number density obtained in the smaller torch.However, the magnitude of the improvement does not seem to be strictly related to either of these factors. The smallest torchJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 25 0.50 0.40 0.30 v) f m 4 - ', 0.20 0.10 I I I b) \ \ s i C) 0 2 4 6 0 2 4 6 0 2 4 6 Ratio of plasma radius to skin depth Fig. 7. Values of b, calculated for input powers of (a) 900, (b) 1200 and (c) 1500 at observation heights of A, 13.0, B, 19.5 and C, 32.5 mm above the load coil ~~ ~ Table 2. Signal to background ratios (SBR) and detection limits (DL) Standard torch Midi-torch Micro-torch DLt/ DL/ DW Ca I . . . . . . . . 422.67 22 0.1 31 0.08 145 0.01 Ca I1 . . . . . . . . 393.37 22 0.1 717 0.007 86 1 0.002 Cu I . . . . . . . . 324.75 8.7 0.5 23 0.2 36 0.1 Fe I .. . . . . . . 371.99 4.7 0.5 6.2 0.4 7.6 0.4 Fe I1 . . . . . . . . 259.94 1.9 2 4.5 1 9.6 0.5 Mg I . . . . . . . . 285.21 7 0.5 33 0.09 43 0.07 Ni I . . . . . . . . 341.48 2.2 3 4.5 2 6.5 1 VII . . . . . . . . 309.31 3.8 0.5 4.5 0.4 5.9 0.3 Zn I . . . . . . . . 213.86 2.3 2 8.5 1 18 0.4 Element Wnm SBR* pgml-1 SBR pgml-1 SBR pgml-l Mg I1 . . . . . . . . 279.55 11 0.3 95 0.03 140 0.02 * Corrected to 2 x 10-7 A V-1 scale and 100 pg ml-l equivalent. 7 Concentration of analyte in pg ml-1 that gave an average signal equal to three times the standard deviation of the blank, actually evaluated at that concentration level. comes close, within a factor of 2-8, to the figures of merit determined for the standard torch at 27 MHz using the same optical system.' Calibration graphs were linear over four or more orders of magnitude in all the torches for all elements in this study. Representative graphs for Ca I1 and Cu I are shown in Fig.8 for the 18- and 10-mm torches. The calibration graph for Ca I1 is starting to become non-linear at 1000 g ml-1 in the micro-torch, due to self reversal of this intense emission line,l7 but not nearly as much as in the standard torch at 27 MHz. The greater sensitivity obtained in the micro-torch is also seen in this figure. The interference of phosphate on the Ca I1 393.37-nm emission from a 3 g ml-1 calcium solution in the NAZ was studied up to a molar ratio of 1300: 1 for P043- : Ca. Behaviour essentially similar to that already publishedlJ8 was observed in this study, with a slight decrease in calcium emission at molar ratios greater than 700 : 1.The emission signal decreases less in the 10-mm torch compared with the standard torch, as shown in Fig. 9. Savage and HieftJe19 reported a somewhat greater level of interference in their micro-torch than is seen here. The refractory compounds postulated as a mechanism for this interference2O-22 are apparently adequately vaporised in the NAZ of the reduced- size torches used in this study. In the standard-size torch at 148 MHz, many common organic solvents (including acetone, benzene, hexane, methanol, toluene, chloroform and xylene) were capable of being aspirated at 1200 W with no change in either operating conditions or matching network tuning from aqueous solu- tions. This is a distinct advantage when a combination of aqueous and organic solutions are to be analysed, or when the composition of the sample solution is 'not known. In the medium-size torch, the more volatile solvents began to create a problem, with benzene quenching the discharge after ca.1.5 min. No re-tuning was required for the other solvents. The smallest torch would not accept organic solvents at 1200 W. The discharge decreased in height and expanded in diameter, such that it could not be kept away from the walls of the coolant tube. This progression in sample handling ability is a direct reflection of the change in the r/s ratio, with the larger torches being most immune to sample introduction effects. The progression in detection limits and freedom from vapod- sation interferences are also correlated with the r/s ratio.26 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL.2 106 105 104 - m 103 .- v, 102 10‘ 1 OU -10-2 10-1 100 101 102 103 104 Concentrationimg I-’ Fig. 8. Analytical calibration graphs for Ca I1 (393.37 nm) in the A, standard and B, micro-size torches, and Cu I (324.75 nm) in the C, standard- and D, micro-torches - .; , 10’ 1 02 103 104 g 60 1 00 Molar ratio of PO4- to Ca I .- - ; I I I I 10‘ 102 I? 6 0 ‘ Fig. 9. Effect of phosphate on calcium ion emission intensity from a 3 pg ml-1 solution in the A, micro-, B, midi- and C, standard-size torches Conclusion The ratio of plasma radius to skin depth is a useful parameter to consider when changing torch sizes or operating frequencies of ICPs. This provides a coherent means of organising and understanding the effects of such changes. Excitation temper- atures and ion to atom intensity ratios roughly follow the trend in rls, but the electron number density tracks rls quite closely. Because of the method of LTE determination, the approach to LTE of these torches also roughly follows the rls ratio.That these effects are not simply a function of the physical distance between the energy deposition region and the analyte channel (r-s) is demonstrated by the behaviour of the standard torch at 27 MHz, which has a net r-s distance nearly equal to that of the 13 mm midi-torch at 148 MHz. The physical characteristics and analytical performance of the standard 27-MHz ICP are most closely approached by the 10-mm micro-torch at 148 MHz, rather than by the midi-torch.This similarity of the standard and micro-torches does not extend to the case of introducing organic solvents at the low powers used for aqueous solutions. The midi-torch accepts organic solvents almost as well as the standard torch, however, and provides intermediate detection limits. For the analysis of organic solutions, a more optimum balance of sensitivity and sample handling is provided by the midi-torch, while freedom from vaporisation interferences is maintained. These effects are well correlated with the various rls ratios of the torches investigated in this study. This research was partially supported by the Office of Naval Research. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.22. References Webb, B. D., and Denton, M. B., Spectrochim. Acta, Part B, 1986,41, 361. Scott, R. H., Fassel, V. A., Kniseley, R. N., and Nixon, D. E., Anal. Chem., 1974,46,75. Savage, R. N., and Hieftje, G. M., Anal. Chem., 1979,51,408. Weiss, A. D., Savage, R. N., and Hieftje, G. M., Anal. Chim. Acta, 1981, 124, 245. Allemand, C. D., Barnes, R. M., and Wohlers, C. C., Anal. Chem., 1979,51, 2392. Koirtyohann, S. R., Jones, J. S., and Yates, D. A., Anal. Chem., 1980,52, 1965. Koirtyohann, S. R., Jones, J. S . , Jester, C. P., and Yates, D. A., Spectrochim. Acta, Part B, 1981, 36, 49. Windsor, D. L., Heine, D. R., and Denton, M. B., Appl. Spectrosc., 1979, 33, 56. Uchida, H., Tanabe, K., Nojiri, Y., Haraguchi, H., and Fuwa, K., Spectrochim. Acta, Part B, 1981, 36,711. Kawaguchi, H., Ito, T., and Mizuike, A., Spectrochim. Acta, Part B, 1981,36,615. Furuta, N., and Horlick, G., Spectrochim. Acta, Part B, 1982, 37,53. Caughlin, B. L., and Blades, M. W., Spectrochim Acta, Part B, 1984,39, 1583. Raaijmakers, I. J. M. M., Boumans, P. W. J. M., Van Der Sijde, B., and Schram, D. C., Spectrochim. Acta, Part B, 1983, 38,697. Alder, J. F., Bombelka, R. M., and Kirkbright, G. F., Spectrochim. Acta, Part B, 1980,35, 163. Boumans, P. W. J. M. , and De Boer, F. J., Spectrochim. Acta, Part B, 1977,32, 365. Furuta, N. , and Horlick, G., Spectrochim. Acta, Part B, 1982, Human, H. C. G., and Scott, R. H., Spectrochim. Acta, PartB, 1976, 31, 459. Larson, G. F., Fassel, V. A., Scott, R. H., and Kniseley, R. N. , Anal. Chem., 1975,47,238. Savage, R. N., and Hieftje, G. M., Anal. Chem., 1980, 52, 1267. Fassel, V. A., andBecker, D. A.,Anal. Chem., 1969,41,1522. Hermann, R., Alkemade, C. Th. J., and Gilbert, P. T., “Chemical Analysis by Flame Photometry,” Interscience, New York, 1963. Fukushima, S . , Mikrochim. Acta, 1959, 596. 37,53. Paper JA612 Received January 27th, 1986 Accepted September 19th, I986

ISSN:0267-9477    

DOI:10.1039/JA9870200021

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 27 Studies of a Low-noise Laminar Flow Torch for Inductively Coupled Plasma Atomic Emission Spectrometry Part 2.* Noise Power Studies and Interference Effects John Davies Trace Analysis Laboratory, Department of Chemistry, Imperial College of Science and Technology, London SW7 ZAY, UK Richard D. Snookt Chelsea Instruments Ltd., Avonmoor Business Centre, Avonmoor Road, London W14, UK Noise power spectra of emission signals from the laminar flow torch (LFT) designed in our laboratory and a conventional tangential flow torch (TFT) are presented and described. It is shown that the fundamental frequency of rotation in a conventional torch is completely removed in the laminar flow torch. Moreover, the use of an extended torch is essential in removing air entrainment effects and also for the maintenance of undisturbed laminar flow.The interference effects of phosphate and sodium on calcium emission are assessed in the laminar flow torch and compared with those in a conventional torch. Phosphate interference is not observed in the laminar flow torch while the effect of sodium on calcium emission is shown to be of the same magnitude in both torches. Keywords : Inductively coupled plasma atomic emission spectrometry; laminar flow torch; noise power; interference effects The inductively coupled plasma atomic emission spectrometry (ICP-AES) technique, like all UV - visible spectrometric techniques, is source-noise limited. Above the background equivalent concentration (BEC) level the ICP is flicker noise limited and therefore detection limits and precision are governed by the inherent optical noise observed in the plasma.This noise is caused by two phenomena: firstly, the rotation of the plasma gases induced by vortex stabilisation (thought necessary in conventional torches to produce a stable dis- charge) and secondly, the fluctuations in the analytical signal caused by the nebuliser and sample introduction system. The effect of the rotation of the rapidly swirling plasma gases is to impose a tangential force upon the injector channel perpendi- cular to its motion, giving rise to two possibilities. The first is simple, the rotating gas merely destabilises the injector channel and introduces a higher level of random noise, and secondly, there are tangential forces on the injector channel that cause rotation of the emitting species.It has been observedl-3 that emission is spatially distributed along the boundary regions of the injector channel where these tangen- tial forces are likely to be greatest. The removal of the former effect would be characterised by a lowering of the white noise level and the removal of the latter effect by the removal of particular frequencies in the noise power spectrum. While the removal of turbulence acting on the injector channel has brought an order of magnitude improvement in detection limits4 the removal of principle frequencies is important for use with Fourier transform spectrometry (FTS).5?6 The reason for this is simple. The principle of operation of a UV - visible FT spectrometer, based on the Michelson interferometer, leads to an interferogram that contains all the information in the form of intensity versus mirror displacement. Thus each spectral element in the source produces a signal at the detector modulated at an audio- frequency proportional to the spectral frequency. Therefore any noise at audio-frequency in the source contributes to the * For Part 1 of this series, see reference 4.t Present address: Department of Instrumentation and Analytical Science, University of Manchester Institute of Science and Technology, PO Box 88, Manchester M60 lQD, UK. interferogram and after Fourier transformation appears as side bands to each spectral line. Thus Belchamber and Horlick7 realised the importance of audio-frequencies in the source in UV - visible FTS when they measured the noise power spectra of optical and acoustic emission signals from an ICP, because their spectrometer required that ICP emission signals be observed with measurement system band widths ranging from 0 to 20 kHz.Thus the absence of audio- frequencies in the ICP source is important for FTS. In Part 1 4 we described the fundamental characteristics of a plasma sustained in a laminar flow torch (LFT) employing an extended outer (coolant) tube extending 40 mm above the load coil (ALC). Noise power spectra of an LFT and a tangential flow torch (TFT) at a viewing height of 25 mm ALC were presented and demonstrated that the LFT effectively removed a frequency component at 117 Hz (presumed to be that due to the rotation of the coolant gas in the TFT).Moreover, the white noise (random noise) level was also shown to be reduced by an order of magnitude in the LFT in comparison with the TIT. In Part 2 we present further noise power spectra of both the LFT and TFT using either short or extended coolant tubes to demonstrate the importance of the use of a torch extension. The interference effects of phosphate and sodium concentration are assessed and compared in the LFT and TFT. Experimental Instrumentation The LFT employed in this study has been described fully in Part l.4 In this study the dimensions of the torch base and quartz tubing in the LFT and TFT were the same. The noise power spectrum analyser used in this study was a Solatron 1200 Digital Signal Processor.Signals from the photomultiplier tube (EM1 6256B) were processed by this unit and presented as decibels, dB, (where dB = -20 logloV) versus frequency on a Hewlett-Packard 7470A X - Y plotter. For the noise power studies a Plasma Therm HF 1500 RF generator and matching network were employed with a Spex 1-m monochromator while for the interference studies an28 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 _ _ _ _ ~ ~~ Table 1. Operating parameters R.f. forward powerkW . . . . . . 1.0 Entranceslitheight/mm . . . . . . 3 Coolantgasflow-ratellmin-1 . . . . 12 Injector gas flow-rate11 min-1 . . . . 0.5 Photomultiplier tube voltage/kV . . 1.4 Entrance/exitslitwidths/pm . . . . 35 Auxiliarygasflow-rate/lmin-l . . 0 International Plasma Corporation generator connected to a capacitively coupled manual matching network was used.Both types of generators have been described fully pre- viously.4 Sample introduction into the ICP was facilitated using a concentric glass nebuliser (Meinhard Associates, Model T-230 A3) combined with a Scott-type double-pass spray chamber. In the short torches the coolant tube extended 2 mm ALC while the long (extended) torches extended 40 mm ALC. Procedure All noise power spectra were obtained whilst nebulising a 10 p.p.m. calcium solution and monitoring the Ca I1 393.366-nm line. The operating parameters for the noise power studies are shown in Table 1. For the interference studies on the calcium emission intensities the operating parameters were the same as those in Table 1 except that the PMT voltage was set at 1.0 kV and intermediate and injector gas flow-rates of 0.2 and 0.8 1 min-1, respectively, used for the LFT; a short coolant tube was employed.For all spatial profiles of emission intensity presented in this study measurements were made at 2,5,8,10, 12, 15, 18, 20, 22 and 25 mm ALC. Reagents All reagents used were of AnalaR grade (BDH Chemicals, Poole, Dorset, UK). De-ionised, distilled water was used throughout the experiments. Results and Discussion Noise Power Studies A series of noise power spectra were recorded of plasmas supported in either an LFT or a TIT fitted with either a short or an extended coolant tube. A comparison was made of two 'types of noise: (a) random noise, or white noise, and ( b ) the presence or absence of noise at discrete frequencies thought to be due to rotation of the plasma in the TFT.Fig. 1 shows a comparison of the magnitude of white noise present in the LFT and TFT (determined on the base line between 500 and 1000 Hz) with viewing height. At all viewing heights the white noise level is less in the L f i than the TFT. This was shown to be a real improvement, rather than to be due to an over-all decrease in sensitivity of the LFT, by comparison of the Ca I1 393.366-nm absolute line intensity in both torches and comparison of the d.c. level that is transformed into the noise power spectrum. The Ca I1 line intensity has been shown4 to be slightly greater for the LFT. We think that this improvement is simply due to the absence of instabilities in the injector channel boundary caused by the rotating plasma gases.To investigate further the source of noise at discrete frequencies the noise power spectra of the TFT and LFT were recorded using extended and short torches at viewing heights of 5,15,30 and 50 mm ALC (Figs. 2 and 3). It is apparent from these figures that the extension of the coolant tube has a marked effect on the noise power spectra obtained. Fig. 2(a) shows the noise power spectra obtained from a TFT using a coolant tube extension of 40 mm. The noise power spectra show one main frequency component at 126 Hz, and the 50-Hz 0 I I 1 I I I I 1 10 20 30 40 50 60 Viewing height/mm ALC Fig. 1. Comparison of the white noise level in A, the LFT and B, the TFT 50 126 B - 50 126 C D 126 126 C D 100 200 300 400 500 600 700 800 900 1000 FrequencyfHz Fig.2. Noise power spectra of (a) an extended (40 mm ALC) and ( b ) a short TFT (2 mm ALC) at viewing heights of: A, 5 ; B, 15; C, 30; and D, 50 mm ALC artefact that is due to the mains electrical frequency. The former frequency component was also found in the noise power spectra of the short TFT, Fig. 2(b). In order to ascertain whether this 126-Hz component was due to the rotation of the coolant gas (no intermediate gas was used) the coolant gas flow-rate was varied in both the short and extended TFTs. Fig. 4 shows the effect of coolant gas flow-rate on the 126-Hz feature frequency present in the noise power spectra of Fig. 2 at a viewing height of 15 mm ALC and using the operating parameters given in Table 1. The frequency was indeed found to shift with change in coolant gas flow-rate.As the flow-rate was increased from 8 to 20 1 min-1 (Fig. 4) the feature frequency increased to a maximum and then decreased. This was also observed by Belchamber and Horlick.7 Presumably this is because as flow-rate increases the angular velocity of the gas also increases. The absence of this frequency component in the L m and the frequency shift with flow-rate clearly indicates that this frequency component is due to the rotation of the coolant gas in the TFT. Furthermore, the maximum frequency at which this occurs appears to depend upon theJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 29 160 140 > S P) g 120 F w- II - - - A 1 75 150 C 75 150 D I 1 I I 1 I 100 200 300 400 500 600 700 800 900 1 FrequencyJHz 0 Fig.3. Noise power spectra of (a) an extended LFT (40 mm ALC) and ( b ) a short LFT (2 mm ALC) at viewing heights of: A, 5 ; B, 15; C, 30; and D, 50 mm ALC 80 1 I I I I I 8 10 12 14 16 18 20 Coolant gas flow-rate/l min-1 Fig. 4. Effect of coolant gas flow-rate on feature frequency in the TFT. A, Torch extension 40 mm ALC; B, torch extension 20 mm ALC; C, torch extension 2 mm ALC. Viewing height 15 mm ALC length of the coolant tube extension. Fig. 4 also shows that when the coolant gas flow-rate is varied in coolant tubes of different lengths the maximum frequency at which the rotational feature occurs increases with increasing extension. These are curious phenomena that are difficult to explain. One possible explanation, however, is that the density of the plasma gas decreases as the torch extension increases, and hence, for a given gas flow-rate the angular velocity of the gas increases, which increases the rotational frequency, (provided the pressure does not change).Indeed, when we look at a plasma sustained in an extended torch it appears less dense than one sustained in a short torch. Further evidence for the decreased density of the plasma with torch extension can be obtained from electron density measurements. Using the H(3 Stark broadening method previously reported4 we have measured the electron density at different viewing heights in both the short and extended TFT m 2.5 c N z 1 2.0 i ? 1.5 C w .- U S 2 tj 1.0 al w - I I I 1 1 I 25 0.5 5 10 15 20 Viewing heightimm ALC Fig.5. Comparison of electron densities in A, a short and B, an extended TFT (Fig. 5). At viewing heights of less than ca. 18 mm the electron density is lower in the extended torch than in the short torch. The lower electron density in the extended torch below 18 mm is because an extended torch sustains an extended and less diffuse plasma. Above 18 mm the situation is reversed because the plasma recombines earlier with respect to viewing height in the short torch (i.e., it is cooled by its emergence into the surrounding atmosphere) whereas in the extended torch the plasma is sustained for a greater distance above the load coil, the torch extension preventing cooling from the surrounding atmosphere until much later. The cross-over in electron densities is expected to be dependent on the relative length of the coolant tube and operating parameters such as injector gas flow-rate and coolant gas flow-rate.The effect of decreasing the density would be to decrease the viscous drag between the plasma and its surroundings. Thus the frequency would be expected to increase, as is observed. This is only a tentative suggestion as there are doubtless several other parameters that need to be measured, e.g., surrounding temperature and axial gas velocity. From Fig. 2(b) it can be seen that the noise power spectra obtained in a short TFT show more frequency components when compared with the noise power spectra obtained in an extended TFT. The most likely cause of the appearance of these additional frequency components in the short TFT is air entrainment effects.As the torch extension was decreased so the appearance of these frequencies occurred lower in the plasma. Moreover, none of these additional frequency com- ponents were found when viewing inside the torch extension. In summarising the spectra obtained for the TFT, it can be seen that the noise power spectra obtained for both the extended and short TFTs possess a fundamental frequency component due to the rotation of the coolant gas. In the short TFT, air entrainment effects produce further frequency components present in the noise power spectra. Fig. 3(a) shows the noise power spectra obtained for an extended LFT. No frequency components appear in the noise power spectra except that due to the mains electrical frequency. However, when a short LFT was employed frequency components were found to appear, Fig.3(b). The difference between the appearance of these frequency com- ponents in the LFT compared with those in the TFT is that in the LFT there is a fall off in intensity of these components between 0 and 15 mm ALC, then there is an increase in intensity up to 30 mm ALC and then a final fall off. In the TFT there is a simple increase in intensity up to 30 mm ALC and then a fall off in intensity. These marked additional frequency components in the short LFT are also due to air entrainment effects, which serve to breakdown the laminar flow establi- shed in the torch, thus increasing the magnitude of the noise and negating the advantage of using the LFT. As might be expected, the values of these additional frequency com-JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL.2 I 1 I I I 5 10 15 20 25 Viewing height/mm ALC Fig. 6. Effect of phosphate concentration on calcium emission in the TFT, for 1 p.p.m. of Ca. (a) Ca 11,393.366 nm; and ( b ) Ca I, 422.673 nm. A, 0; B, 10; C, 100; and D, 1000 p.p.m. of phosphate ponents are different in both torches due to the difference between the laminar and tangential flow patterns. Thus in order to maintain laminar flow in the plasma sustained in the LFT it is essential to employ an extended torch. One of the possible problems that might arise from the use of extended torches is the gradual devitrification of the torch, which makes viewing through the torch extension undesirable. Certainly with the TFT “fogging” of the tubes in this way decreases the analytical signal after a few weeks.The LFT does not appear to suffer from this problem presumably because of enhanced cooling efficiency obtained by using laminar flow, or because laminar flow prevents heat transfer from the plasma to the quartz. Indeed we have been using the same torch extension daily for three months without signs of devitrification or fogging. Interference Studies Fig. 6 shows the effect of phosphate concentration on the spatial profiles of emission intensity of the Ca I1 393.366-nm line and the Ca 1422.673-nm line in the m. The Ca I1 spatial emission profile is seen to be shifted very slightly away from the load coil as the concentration of phosphate increases. The magnitude of emission is also seen to be reduced by ca.10% for a phosphate concentration of 1000 p.p.m. No shift in the spatial emission profile is observed for the Ca I line but a decrease in emission intensity of the same order as that for Ca I1 is seen. However, in the LFT no effect was seen on the spatial profiles of Ca I and Ca I1 emission intensities or the magnitude of emission. (Moreover, when an end-on viewing configuration was employed8 the presence of phosphate up to 1000 p.p.m. did not affect the emission intensities either. However, in the TFT phosphate interference has been shown to be worse in an end-on viewing configuration.8) A figure for the effect of phosphate concentration on calcium emission in the LFT is not shown as all four lines would be superimposed upon each other.The effect of sodium concentration on the emission intensities of the Ca I and Ca I1 lines for both types of plasma 5 10 15 20 25 Viewing heightlmm ALC Fig. 7. Effect of sodium concentration on (a) Ca I and ( b ) Ca I1 emission intensity, in the TFT (solid line) and LFT (broken line), 1 p.p.m. of Ca. Sodium concentrations: A, 1OOO; B, 100; and C, 10 p.p.m. are shown in Fig. 7 as an enhancement factor, i.e., the ratio of the calcium emission intensity of a solution with 1 p.p.m. of Ca plus the sodium matrix to the calcium emission intensity of a solution with 1 p.p.m. of Ca without the matrix. The presence of such an interference is clear and in both plasmas the magnitude of the interference was found to be similar. The reason why there is an absence of a phosphate interference but the presence of a sodium interference is present is due to the nature of the interferences.The phosphate interference is a classical volatilisation interference effect.9 Optimisation of the conventional ICP source reduces the magnitude of phosphate interference9 and it would appear that in the LFT we have obtained conditions where no such interference occurs. Although the exact nature of the sodium interference is not fully characterised it is not a volatilisation effect but it is more likely to be due to a change in electron density and temperature. The similarity in magnitude of the sodium interference in both torches is due to the fact that the presence of similar amounts of matrix changes the excitation conditions in both torches to the same extent. Conclusions The replacement of tangential flow by laminar flow in the ICP torch has reduced the level of random noise associated with the injector channel by an order of magnitude and removed the fundamental frequency due to the rotation of the coolant gas on the analyte emission signal.Moreover, it is clear from these results that the use of an extended torch is essential to maintain the low noise capability of the laminar flow torch and prevent any disturbance from air entrainment effects that serve to break down the laminar flow established in the torch. The effect of the extended torch is to sustain a plasma, which, when compared with a plasma sustained in a short torch, is less dense near the load coil region because the plasma becomes extended, but decays less rapidly to equilibrium because of the exclusion of the surrounding cold environment until muchJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL.2 31 further up the discharge. The use of torch extensions are by no means detrimental in AES as devitrification in the LFT is much less severe in comparison with the TFT. In our own laboratory one extended torch has lasted for three months of continuous daily use without showing any sign of devitrifica- tion. [Any problem of devitrification is, of course, overcome by the use of end-on (axial) viewing,g which maximises the advantage of simultaneous multi-element determinations with the low-noise laminar flow torch.] The interference effect of sodium on Ca I and Ca I1 emission intensities have been shown to be of the same order of magnitude in both torches. Phosphate interference is not observed in the LFT plasma while a slight depression is observed in the Tm. We have demonstrated that a plasma sustained in an LFT has no disadvantages compared with one sustained in a TFT. Its superior performance in terms of phosphate interference and reduction in noise makes it a superior alternative to the conventional TFT. We acknowledge the support of J. D. by the SERC and Chelsea Instruments Ltd. under the CASE Studentship Scheme. We also thank Dr. J. F. Alder of the DIAS, UMIST, Manchester, for the use of the noise power spectrum analyser and Plasma Therm HF 1500 ICP. 1. 2. 3. 4. 5. 6. 7. 8. 9. References Furuta, N. , and Horlick, G., Spectrochim. Acta, Part B, 1982, 37, 53. Eckert, H. U., and Danielsson, A. , Spectrochim. Acta, Part B, 1984,39, 15. Caughlin, B. L., and Blades, M. W . , Spectrochim. Acta, Part B, 1984,39, 1583. Davies, J., and Snook, R. D., J. Anal. At. Spectrom., 1986,1, 195. Thorne, A. P., Anal. Proc., 1985,22, 63. Horlick, G., and Yuen, W. K., Appl. Spectrosc., 1978,32,38. Belchamber, R. M., and Horlick, G., Spectrochim. Acta, Part B, 1982,37, 17. Davies, J., Dean, J. R., and Snook, R. D., Analyst, 1985,110, 535. Kornblum, G. R., and de Galan, L., Spectrochim. Acta, Part B, 1977,32,455. Note-Reference 4 is to Part 1 of this series. Paper J6l35 Received May 8th, 1986 Accepted August lst, 1986

ISSN:0267-9477    

DOI:10.1039/JA9870200027

出版商:RSC    

年代:1987

数据来源: RSC