The AnalystThe Analytical Journal of The Royal Society of ChemistryAdvisory Board"Chairman: J. D. R. Thomas (Cardiff, UK)D. Betteridge (Sunbury-on-Thames,E. Bishop (Exeter, UK)W. L. Budde (USA)*C. Burgess (Ware, UK)D. T. Burns (Belfast, UK)*M. S. Cresser (Aberdeen, UK)L. de Galan (The Netherlands)D. Dyrssen (Sweden)*A. G. Fogg (Loughborough, UK)*C. W. Fuller (Nottingham, UK)V. D. Goldberg (London, UK)J. Hoste (Belgium)A. Hulanicki (Poland)*C. J. Jackson (London, UK)W. S. Lyon (USA)*P. M. Maitlis (Sheffield, UK)H. V. Malmstadt (USA)E. J. Newman (Poole, UK)UK) "J. M. Ottaway (Glasgow, UK)T. B. Pierce (Hamell, UK)E. Pungor (Hungary)J. R8iiEka (Denmark)P. H. Scholes (Middlesbrough, UK)D. Simpson (Thorpe-le-Soken, UK)R. M.Smith (Loughborough, UK)W. I. Stephen (Birmingham, UK)M. Stoeppler (Federal Republic of Germany)K. C. Thompson (Sheffield, UK)*A. M. Ure (Aberdeen, UK)A. Walsh, K.B. (Australia)G. Werner (German Democratic Republic)T. S. West (Aberdeen, UK)*P. C. Weston (London, UK)J. D. Winefordner (USA)P. Zuman (USA)"Members of the Board serving on the Analytical Editorial BoardRegional Advisory EditorsFor adviceand help to authors outside the UKDr. J. Aggett, Department of Chemistry, University of Auckland, Private Bag, Auckland, NEWDot. Dr. sc. K. Dittrich, Analytisches Zentrum, Sektion Chemie, Karl-Marx-Universitat, Talstr.Professor L. Gierst, Universite Libre de Bruxelles, Faculte des Sciences, Avenue F.-D.Professor H. M. N. H. Irving, Department of Analytical Science, University of Cape Town,Dr.0. Osibanjo, Department of Chemistry, University of Ibadan, Ibadan, NIGERIA.Dr. G. Rossi, Chemistry Division, Spectroscopy Sector, CEC Joint Research Centre,Dr. 1. RubeSka, Geological Survey of Czechoslovakia, Malostranske 19, 118 21 Prague 1,Professor K. Saito, Coordination Chemistry Laboratories, Institute for Molecular Science,Professor M. Thompson, Department of Chemistry, University of Toronto, 80 St. GeorgeProfessor P. C. Uden, Department of Chemistry, University of Massachusetts, Amherst,Professor Dr. M. Valcarcel, Departamento de Quimica Analitica, Facultad de Ciencias,ZEALAN D.35, DDR-7010 Leipzig, GERMAN DEMOCRATIC REPUBLIC.Roosevelt 50, Bruxelles. BELGIUM.Rondebosch 7700, SOUTH AFRICA.EURATOM, lspra Establishment, 21020 lspra (Varese), ITALY.CZECHOSLOVAKIA.Myodaiji, Okazaki 444, JAPAN.Street, Toronto, Ontario M5S 1A1, CANADA.MA 01003, USA.Universidad de Cordoba, 14005 Cordoba, SPAIN.Editor, The Analyst:Philip C.WestonSenior Assistant Editors:Judith Brew, Roger A. YoungAssistant Editor:Anne HorscroftEditorial Office: The Royal Society of Chemistry, Burlington House,Piccadilly, London, W1V OBN. Telephone 01-734 9864. Telex No. 268001Advertisements: Advertisement Department, The Royal Society of Chemistry, BurlingtonHouse, Piccadilly, London, W1V OBN. Telephone 01-437 8656. Telex No. 268001The Analyst (ISSN 0003-2654) is published monthly by The Royal Society of Chemistry,Burlington House, London W1V OBN, England. All orders accompanied with payment shouldbe sent directly to The Royal Society of Chemistry, The Distribution Centre, Blackhorse Road,Letchworth, Herts. SG6 lHN, England.1986 Annual subscription rate UK f147.00, Rest ofWorld €162.00, USA $285.00. Purchased with Analytical Abstracts UK f329.00, Rest of World€361 .OO, USA $636.00. Purchased with Analytical Abstracts plus Analytical Proceedings UKf375.00, Rest of World €412.00, USA $726.00. Purchased with Analytical Proceedings UK€184.00, Rest of World f202.00, USA $356.00. Air freight and mailing in the USA byPublications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003.USA Postmaster: Send address changes to: The Analyst, Publications Expediting Inc., 200Meacham Avenue, Elmont, NY 11003.Second class postage paid at Jamaica, NY 11431. Allother despatches outside the UK by Bulk Airmail within Europe, Accelerated Surface Postoutside Europe. PRINTED IN THE UK.Information for AuthorsFull details of how to submit material forpublication in The Analyst are given in theInstructions to Authors in the January issue.Separate copies are available on request.The Analyst publishes papers on all aspects ofthe theory and practice of analytical chemistry,fundamental and applied, inorganic andorganic, including chemical, physical, biochem-ical, clinical, pharmaceutical, biological, auto-matic and computer-based methods. Papers onnew approaches to existing methods, newtechniques and instrumentation, detectors andsensors, and new areas of application with dueattention to overcoming limitations and to un-derlying principles are all equally welcome.There is no page charge.The following types of papers will be con-sidered:Full papers, describing original work.Short papers, also describing original work,but shorter and of limited breadth of subjectmatter; there will be no difference in the qualityof the work described in full and short papers.Communications, which must be on anurgent matter and be of obvious scientificimportance.Rapidity of publication is enhancedif diagrams are omitted, but tables and formulaecan be included, Communications should not besimple claims for priority: this facility for rapidpublication is intended for brief descriptions ofwork that has progressed to a stage at which it islikely to be valuable to workers faced withsimilar problems. A fuller paper may be offeredsubsequently, if justified by later work.Reviews, which must be a critical evaluationof the existing state of knowledge on a par-ticular facet of analytical chemistry.Every paper (except Communications) will besubmitted to at least two referees, by whoseadvice the Editorial Board of The Analystwill beguided as to its acceptance or rejection. Papersthat are accepted must not be published else-where except by permission.Submission of amanuscript will be regarded as an undertakingthat the same material is not being consideredfor publication by another journal.Regional Advisory Editors.For the benefit ofpotential contributors outside the United King-dom, a Panel of Regional Advisory Editorsexists. Requests for help or advice on anymatter related to the preparation of papers andtheir submission for publication in The Analystcan be sent to the nearest member of the Panel.Currently serving Regional Advisory Editors arelisted in each issue of The AnalystManuscripts (three copies typed in double spac-ing) should be addressed to:The Editor, The Analyst,Royal Society of Chemistry,Burlington House,Piccadi I I y,LONDON WIV OBN, UKParticular attention should be paid to the use ofstandard methods of literature citation, includingthe journal abbreviations defined in ChemicalAbstracts Service Source Index. Wherever pos-sible, the nomenclature employed should fol-low IUPAC recommendations, and units andsymbols should be those associated with SI.All queries relating to the presentation andsubmission of papers, and any correspondenceregarding accepted papers and proofs, shouldbe directed to the Editor, The Analyst (addressas above). Members of the Analytical EditorialBoard (who may be contacted directly or via theEditorial Office) would welcome comments,suggestions and advice on general policy mat-ters concerning The Analyst.Fifty reprints of each published contribution aresupplied free of charge, and further copies canbe purchased.@ The Royal Society of Chemistry, 1986. Allrights reserved. No part of this publication maybe reproduced, stored in a retrieval system, ortransmitted in any form, or by any means,electronic, mecha n ica I, photog rap h ic, record-ing, or otherwise, without the prior permissionof the publishers