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FOLD HEREI I \ I 1 1 I I [ 5 COUNTYTHE ANALYST READER ENQUIRY SERVICE J U N E'939 TELEPhONE NOFor further information about any of the products featured in the advertisements in this issue, please writethe appropriate number in one of the boxes below.Postage paid if posted in the British Isles but overseas readers must affix a stamp.I I 1 1-1 OFFICEUSEONLY I i E L D PRO( 0 1 ' ' I !FOLD HEREIIIIIIIIIIIIIIIIIiIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIPostagewill bepaid byLicenseeDo not affix Postage Stamps if posted in Gt. Britain,Channel Islands, N. Ireland or the Isle of ManBUSINESS REPLY SERVICELicence No. WD 106Reader Enquiry ServiceThe AnalystThe Royal Society of ChemistryBurlington House, PiccadillyLONDONWIE 6WFEnglandIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII!IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

ISSN:0003-2654    

DOI:10.1039/AN99318BP019

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

AnalystThe Analytical Journal of The Royal Society of ChemistryAnalytical Editorial BoardChairman: A. G. Fogg (Loughborough, UK)K. D. Bartle (Leeds, UK)H. M. Frey (Reading, UK)D. E. Games (Swansea, UK)J. M. Gordon (Cambridge, UK)S. J. Hill (Plymouth, UK)D. L. Miles (Keyworth, UK)J. N. Miller (Loughborough, UK)R. M. Miller (Port Sunlight, UK)B. L. Sharp (Loughborough, UK)M. R. Smyth (Dublin, Ireland)J. F. Alder (Manchester, UK)A. M. Bond (Victoria, Australia)R. F. Browner (Atlanta, GA, USA)D. T. Burns (Belfast, UK)J. G. Dorsey (Cincinnati, OH, USA)L. Ebdon (Plymouth, UK)A. F. Fell (Bradford, UK)J. P. Foley (Villanova, PA, USA)M. F. Gine (Sao Paulo, Brazil)T. P. Hadjiioannou (Athens, Greece)W. R. Heiheman (Cincinnati, OH, US.A. Hulanicki (Warsaw, Poland)I.Karube (Yokohama, Japan)E. J. Newman (Poole, UK)J. Pawliszyn ( Waterloo, Canada)Advisory BoardT. B. Pierce (Harwell, UK)E. Pungor (Budapest, Hungary)J. RGliCka (Seattle, WA, USA)R. M. Smith (Loughborough, UK)K. Stulik (Prague, Czechoslovakia)J. D. R. Thomas (Cardiff, UK)J. M. Thompson (Birmingham, UK)K. C. Thompson (Sheffield, UK)P. C. Uden (Amherst, MA, USA)A. M. Ure (Aberdeen, UK)C. M. G. van den Berg (Liverpool, UK)A. Walsh, KB (Melbourne, Australia)J. Wang (Las Cruces, NM, USA)T. S. West (Aberdeen, UK)A ) P. Vadgama (Manchester, UK)Regional Advisory EditorsFor advice and help to authors outside the UKProfessor Dr. U. A. Th. Brinkman, Free University of Amsterdam, 1083 de Boelelaan, 1081 HVAmsterdam, THE NETHERLANDS.Professor P.R. Coulet, Laboratoire de Genie Enzymatique, EP 19 CNRS-Universite ClaudeBernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex,FRANCE.Professor Dr. sc. K. Dittrich, Institute for Analytical Chemistry, University Leipzig, Linnestr. 3,0-0-7010 Leipzig, GERMANY.Professor 0. Osibanjo, Department of Chemistry, University of Ibadan, Ibadan, NIGERIA.Professor F. Palmisano, Universita Degli Studi-Bari, Departimento di Chimica CampusProfessor K. Saito, Coordination Chemistry Laboratories, Institute for Molecular Science,Dr. Y. Thomassen, Arbeidsmiljo Instituttet, National Institute of Occupational Health, GydasProfessor M. Thompson, Department of Chemistry, University of Toronto, 80 St.GeorgeProfessor Dr. M. Valcarcel, Departamento de Quimica Analitica, Facultad de Ciencias,Professor J. F. van Staden, Department of Chemistry, University of Pretoria, Pretoria 0002,Professor Yu Ru-Qin, Department of Chemistry and Chemical Engineering, Hunan University,Professor Yu. A. Zolotov, Kurnakov Institute of General and Inorganic Chemistry, 31 LeninUniversitario, 4 Trav. 200 Re David-70126 Bari, ITALY.Myodaiji, Okazaki 444, JAPAN.Vei 8, P.B. 8149 Dep, N-0033 Oslo 1, NORWAY.Street, Toronto, Ontario, CANADA M5S I A I .Universidad de Cordoba, 14005 Cordoba, SPAIN.SOUTH AFRICA.Changsha, PEOPLES REPUBLIC OF CHINA.Avenue, 117907, Moscow V-71, RUSSIA.Editorial Manager, Analytical Journals: Janice M. GordonEditor, The AnalystHarpal S.MinhasThe Royal Society of Chemistry,Thomas Graham House, Science Park,Milton Road, Cambridge, UK CB4 4WFTelephone +44(0)223 420066.Fax +44(0)223 420247. Telex No. 818293 ROYAL.US Associate Editor, The AnalystDr Julian F. TysonDepartment of Chemistry,University of Massachusetts,Amherst MA 01003, USATelephone + I 413 545 0195Fax + 1 41 3 545 4490Senior Assistant Editor Assistant EditorPaul Delaney Sheryl YouensEditorial Secretary: Claire HarrisAdvertisements: Advertisement Department, The Royal Society of Chemistry, BurlingtonHouse, Piccadilly, London, UK WIV OBN. Telephone +44(0)71-437 8656. Telex No. 268001.Fax +44(0)71-437 8883.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 aspectsof the theory and practice of analyticalchemistry, fundamental and applied, inor-ganic and organic, including chemical,p hysica I, bioche m ica I, cI in ica I, p h a rma-ceutical, biological, environmental, automa-tic and computer-based methods.Papers onnew approaches to existing methods, newtechniques and instrumentation, detectorsand sensors, and new areas of applicationwith due attention to overcoming limitationsand to underlying principles are all equallywelcome. There is no page charge.The following types of papers will beconsidered:Full research papers.Communications, which must be on anurgent matter and be of obvious scientificimportance.Rapidity of publicatiori isenhanced if diagrams are omitted, but tablesand formulae can be included. Communica-tions receive priority and are usually pub-lished within 5-8 weeks of receipt. They areintended for brief descriptions of work thathas progressed to a stage at which it is likelyto be valuable to workers faced with similarproblems. A fuller paper may be offeredsubsequently, if justified by later work.Although publication is at the discretion ofthe Editor, communications will be exa-mined by at least one referee.Full critical reviews, which must be acritical evaluation of the existing state ofknowledge on a particular facet of analyticalc he m ist ry.Every paper (except Communications) willbe submitted to at least two referees, bywhose advice the Editorial Board of TheAnalyst will be guided as to its acceptance orrejection.Papers that are accepted must notbe published elsewhere except by per-mission. Submission of a manuscript will beregarded as an undertaking that the samematerial is not being considered for publica-tion by another journal.Regional Advisory Editors. For the benefitof potential contributors outside the UnitedKingdom and North America, a Group ofRegional Advisory Editors exists. Requestsfor help or advice on any matter related tothe preparation of papers and their sub-mission for publication in The Analystcan besent to the nearest member of the Group.Currently serving Regional Advisory Editorsare listed in each issue of The Analyst.Manuscripts (four copies typed in doublespacing) should be addressed to:H.S. Minhas, Editor, orJ. F. Tyson, US Associate EditorParticular attention should be paid to the useof standard methods of literature citation,including the journal abbreviations definedin Chemical Abstracts Service Source Index.Wherever possible, the nomenclatureemployed should follow IUPAC recommen-dations, and units and symbols should bethose associated with SI.All queries relating to the presentation andsubmission of papers, and any correspon-dence regarding accepted papers and pro-ofs, should be directed eitherto the Editor, orAssociate Editor, The Analyst (addresses asabove).Members of the Analytical EditorialBoard (who may be contacted directly or viathe Editorial Office) would welcomecomments, suggestions and advice ongeneral policy matters concerning TheAnalyst.Fifty reprints are supplied free of charge.The Analyst (ISSN 0003-2654) is published monthly by The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road,Cambridge, UK CB4 4WF. All orders, accompanied with payment by cheque in sterling, payable on a UK clearing bank or in US dollars payableon a US clearing bank, should be sent directly to The Royal Society of Chemistry, Turpin Distribution Services Ltd., Blackhorse Road,Letchworth, Herts, UK SG6 IHN. Turpin Distribution Services Ltd., is wholly owned by the Royal Society of Chemistry.1993 Annual subscriptionrate EC €301.00, USA $662.00, Canada f348.00 (excl. GST), Rest of World f331.00. Purchased with Analytical Abstracts EC f656.00, USA$1444.00, Canada f758.00 (excl. GSTj, Rest of World f722.00. Purchased with Analytical Abstracts plus Analytical Proceedings EC €774.40, USA$1703.68, Canada f894.00 (excl. GST), Rest of World f851.84. Purchased with Analytical Proceedings EC f383.00, USA $842.00, Canada €442.00(excl. GST), Rest of World f421.00. Airfreight and mailing in the USA by Publications Expediting Inc., 200 Meacham Avenue, Eltnont, NY 11003.USA Postmaster: Send address changes to: The Analyst, Publications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003. Second classpostage paid a t Jamaica, NY 11431. All other despatches outside the UK by Bulk Airmail within Europe, Accelerated Surface Post outsideEurope. PRINTED IN THE UK. 0 The Royal Society of Chemistry, 1993. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, ortransmitted in any form, or by any means, electronic, mechanical, photographic, recording, or otherwise, without the prior permission of thepublishers

ISSN:0003-2654    

DOI:10.1039/AN99318FX021

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALAO 1 18(6) 583-736,65N-80N (1 993)AnalystJune 1993The Analytical Journal of The Royal Society of ChemistryCONTENTS65N Conference Report-SAC '92-J. D. R. Thomas58358759360 160961361762362763363964364965766 1665669The Opening Address t o SAC '92-Laboratory of the Government Chemist, Past and Future-Richard WorswickDevelopment of an International Chemical Measurement System-Plenary Lecture-B.ernard KingFlow-through (Bio)Chemical Sensors-Plenary LectureMiguel Valcarcel, Maria Dolores Luque de CastroPAPERSAttomole Detection of Nitroaromatic Vapours Using Resonance Enhanced Multiphoton Ionization Mass Spec-trometry-Alastair Clark, Kenneth W. D. Ledingham, Archibald Marshall, Joseph Sander, Ravi P. SinghalAnalysis of Steroids.Part 46. Qualitative and Quantitative Characterization of Bulk Cholesterol by Gas Chromato-graphy and Gas Chromatography-Mass Spectrometry-Anna Lauko, Eva Csizer, Sandor GorogPhotobleaching of Methylene Blue in Continuous Wave Thermal Lens Spectrometry-Roger D. Lowe, Richard D.SnookPartial Least Squares Resolution of Multianalyte Flow Injection Data-Paul MacLaurin, Paul J. Worsfold, PhilipNorman, Michael CraneDetermination of Iodide Ion in Impregnated Charcoals by Flow Injection-Cheryl D. Monks, Duangjai Nacapricha, ColinG. TaylorFlow Injection Chemiluminometric Determination of Epinephrine, Norepinephrine, Dopamine and L-Dopa-Ni kolaos T.Deftereos, Antony C. Calokerinos, Constantinos E. EfstathiouContinuous-flow Chemiluminometric Determination of Tetracyclines in Pharmaceutical Preparations and Honey byOxidation with N-Bromosuccinimide-Stergios A.Halvatzis, Meropi M. Timotheou-Potamia, Antony C. CalokerinosDetermination of Ascorbic Acid by Flow Injection With Chemiluminescence Detection-Abdulrahman A. AlwarthanFlow Injection Chemiluminescence Method for the Selective Determination of Chromium(iii)-Rosario Escobar,Qingxiong Lin, Alfonso Guiraum, Francisco F. de la RosaPhase-selective Alternating Current Adsorptive Stripping Voltammetry of Aminopterin on a Mercury Thin Film CarbonFibre Ultramicroelectrode-Michael A. Malone, Agustin Costa Garcia, Paulino Tution Blanco, Malcolm R. SmythDetermination of Atmospheric Sulfur Dioxide by Differential-pulse Polarography Using Selenite-Guler Somer, AliKoGakInvestigation of Polymorphism of Mexiletine Hydrochloride by Fourier Transform Infrared and Differential ScanningCalorimetric Techniques-Attila Kiss, Janos RepasiPalladium-Magnesium Nitrate as a Chemical Modifier for the Determination of Lead in Mussel Slurries byElectrothermal Atomic Absorption Spectrometry-Pilar Bermejo-Barrera, Manuel Aboal-Somoza, Rosa M.Soto-Ferreiro, Raquel Dominguez-GonzalezSeparation and Determination of Thiosulfate, Sulfite and Sulfide in Mixtures-Tomozo Koh, Katsuaki Okabe, YasuyukiMiura673674 Foreword-KAC '92675 An Account of Kinetic Determinations and Other Kinetic Aspects of Analytical Chemistry: from Cordoba t o681Fourth International Symposium on Kinetics in Analytical ChemistryErlangen-Horacio A.MottolaTUTORIAL REVIEW-Recent Strategies in Automated Reaction Rate Based Determinations-Manuel SilvaPAPERS689 Kinetic Effects in Surface-enhanced Raman Spectroscopy: Does it Have Potential as an Analytical Tool?-Siegfried695 Extended Kalman Filter for Multiwavelength, Multicomponent Kinetic Determinations-Brett M. Quencer, Stanley R.703 In Situ Measurements on Surfactant-Mineral Interactions by Polarographic Adsorption Kinetics-Franz-Hu bert707 Simultaneous Kinetic Fluorimetric Determination of Amoxycillin and Clavulanic Acid by the Stopped-flow Mixing71 1 Decomposition of 2,6-Dichlorophenolindophenol in Strongly Acidic Solutions: a Potential Kinetic Method for theSchneider, Harald Grau, Peter Halbig, Ulrich NickelCrouchHaegel, Monika Konig, Milan Johann SchwugerTechnique-Pilar Izquierdo, Agustina Gomez-Hens, Dolores Perez-BenditoDetermination of pH-Constantina N.Konidari, Christos G. Nanos, Miltiades I. KarayannisContinued on Inside Back CoverTypeset and printed by Black Bear Press Limited, Cambridge, England103-2651tC199336.1-715 Use of the Triiodide-Hexadecylpyridinium Chloride Micellar System for the Kinetic Determination ofMolybdenum(v1)-Maria Loreto Lunar, Soledad Rubio, Dolores Perez-Bendito719 Trial Measurements in Flow Analysis-Boaventura Freire dos Reis, Elias Ayres Guidetti Zagatto, Patricia BenediniMartelli, Sandra Maria Boscolo Brienza723 Immobilization of Glutamate Oxidase on Non-porous Glass Beads. Automated Flow Injection System for the Assay ofGlutamic Acid in Food Samples and Pharmaceuticals-Constantine D.Stalikas, Miltiades I. Karayannis, Stella M.Tzouwara-Karaya nni727 Substitution of Peroxidase in Trinder's Reagent with Iron(i1) for the Determination of Hydrogen Peroxide in EnzymicReactions by Applying Flow Injection-Efstratios R. Kiranas, Stella M. Tzouwara-Karayanni, Miltiades I. KarayannisCOMM U NlCATl ON731 Use of Poly(L4ysine) and Ascorbic Acid for Surface Enhanced Resonance Raman Scattering Analysis of Acidic MonoazoDyes-C. H. Munro, W. E. Smith, P. C. White735 CUMULATIVE AUTHOR INDEX69N Conference Diary74N Book Reviews79N Papers in Future IssuesCOYAL SOCIETYIF CHEMISTRYUnderslAn lntroduci2nd EditionEdited by R.M. HThis 2nd edition cgreatly updated, Iand environment;The book describatmosphere, freslbehave in these renvironmental pnenvironmental cohuman health efftcase studies areThis unique introcand first year poschemistry, as we1consultancy whoSoftcoverISBN 0 85186 23August 1992SOCIETY OFC H E M ISTRY:anding Our Environment:tion to Environmental Chemistry and Pollutionarrison University of BirminghamIf Understanding Our Environment has been reworked andxoviding a modern introductory level text for students of pollution31 chemistry.les the basic concepts in relation to the chemistry of thehwaters, oceans and soils, as well as the ways in which pollutantsnedia (exemplified by case studies based upon topical3blems).It also examines the transfer of pollutants between differentmpartments, the monitoring of the environment, the ecological andx t s of chemical pollution, economics and regulatory control.Againused throughout.juctory text will be essential reading for students on undergraduatetgraduate courses dealing with pollution and environmental1 as for scientists and engineers in industry, public service andrequire a basic understanding of environmental processes.xvi + 326 pages30 Price f19.50To Order, Please write to the: Royal Society of Chemistry,Turpin Distribution Services Limited, Blackhorse Road, Letchworth, HertsSG6 1 HN. UK. or telephone (0462) 672555 quoting your credit card details.We accept AccessNisalMasterCardlEurocard.Turpin Distribution Services Limited is wholly owned by the Royal Societyof Chemistry.For information on other books and journals, please write to the:Royal Society of Chemistry, Sales and Promotion Department,ThomasGraham House, Science Park, Milton Road, Cambridge CB4 4WF, UK.-+-w V" r s*w - * * YNiemantsverdriet, J.W.Spectroscopy in CatalysisAn Introduction1993. Ca 250 pages with 178 figuresand 26 tables. Hardcover. f 61 .OO.ISBN 3-527-28593-8Both textbook and monograph, 'Spectroscopyin Catalysis' describes the most importantmodern analytical techniques used to investi-gate catalysts or related systems. Like a mono-graph, it covers recent research. Like a text-book, it offers numerous graphics to explain thebasics of each spectroscopic technique. An en-joyable and clearly written introduction to thecharacterization of catalysts.To order please contact your bookseller or:VCH, P.O. Box 10 11 61, D-69451 Weinheim,Telefax (0) 62 01 - 60 61 84VCH, Hardstrasse 10, P.O. Box, CH-4020 Base1VCH, 8 Wellington Court, Cambridge CBl 1 HZ, UKVCH, 220 East 23rd Street,New York, NY 1001 0-4606, USA(toll free: 1-800-367-8249)VCH, Eikow Building,10-9 Hongo 1 -chome,Bunkyo-ku, Tokyo 11 3, Japan VCHx4InformationServicesCircle 002 for further informationRSC Members should obtain members prices and order from:The Membership Affairs Department at the Cambridge address above. ICircle 001 for further informatio

ISSN:0003-2654    

DOI:10.1039/AN99318BX023

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JUNE 1993, VOL. 118 65N Conference Report SAC ’92, an International Conference on Analytical Chemistry: September 20-26, 1992, Reading, UK Towards Continuing Professional Competence in Analytical Chemistry: An Expression of SAC ’92 Weatherwise, SAC ’92 was the wettest of all the series of triennial conferences, first organized by the Society for Analytical Chemistry (SAC) at the University of Nottingham in 1965. Nevertheless, this enhanced the role of the event to be a medium contributing towards promoting the continuing professional competence of the Conferees. SAC ’92 was a double celebration as it also marked the 150th anniversary of the founding of the Laboratory of the Government Chemist (LGC). Because of this anniversary, the Analytical Division of The Royal Society of Chemistry (RSC) was joined by the LGC in the organization of SAC ’92; and helped also by representatives of the Symposia on Spectros- copy Across the Spectrum, as the third symposium of that series was also incorporated into SAC ’92.special Wednesday morning session on ‘Registration of Analytical Chemists’. The highlight of the Opening Ceremony was the Official Opening Address of Dr. G. Robinson, Chief Adviser on Science and Technology in the Department of Trade and Industry. This was followed by the Opening Address by the Government Chemist, Dr. Richard Worswick on ‘Laboratory of the Government Chemist, Past and Future’ (see page 455)’ which set the scene for both the 150th Anniversary Celebra- tions and for SAC ’92 itself with its natural emphasis on the quality of analytical measurements.Arrival and Opening Session The customary buffet dinner and welcome reception on the Sunday afternoon provided the opportunity of renewing friendships, making new ones, and catching up on news and new developments. Dr. Richard Worswick Dr. Bernard King The special association of SAC ’92 with the work of the LGC was brought home by the first Plenary Lecture of the event given by the Government Analyst, Dr. Bernard King, on ‘The Development of an International Measurement System’, a timely theme in regard to professional develop- ment. The platform party prior to the Opening Ceremony. Back row (L-R): Dr. J. S. Gow (Secretary-General, RSC), Professor G . Den Boef (IUPAC) and Professor J. Mann (University of Reading). Front row (L-R): Professor C.W. Rees (President, RSC), Dr. G. Robinson (DTI), .Dr. E. J . Newman (President, Analytical Division), Dr. R. D. Worswick (The Government Chemist) and Mr. P. G. W. Cobb (Chairman, SAC ’92 Executive Committee) The settling-in process required digestion of the week’s scientific and other fare as laid out in the SAC ’92 Conference Handbook. There were 75 pages of tightly packed material, so that the accompanying Summary Programme Card was a well- fingered aid in planning the week ahead. Individual choices from the extensive menu were based on summaries of the 101 lectures (including Plenary Lectures) and 174 posters (although unfortunately some authors did not afford conferees the courtesy of presenting their posters). Decisions were frequently difficult because of the high quality of the lecture programme and the impossibility of being in more than one lecture theatre at a time.No such problems arose with the Opening Ceremony (in the capable hands of the SAC ’92 and LGC 150th Anniversary Executive Committee Chairman, Mr. P. G. W. Cobb), Plenary Lectures, or the The Scientific Sessions The Scientific Programme got under way on the Monday afternoon with the Plenary Lecture given by a speaker brave enough and of sufficient foresight to have specialized early on in the belatedly recognized important area of air chemistry and air analysis. This was by Professor D. Klockow (Dort- mund, Germany) who spoke on ‘Speciation in Atmospheric Trace Analysis: Analytical Chemistry With Inadequacies and Compromises’.Professor Dieter Klockow Professor Tony Fell66N ANALYST, JUNE 1993, VOL. 118 The Conference then divided into its constituent streams A, B and C, with stream A catering for the Spectroscopy Across the Spectrum Symposium; and a poster session on molecular spectroscopy; stream B was devoted to the environment, initially of water and air, and then food and agriculture, and a poster session on environmental considerations. It was but a small step for stream B to be then directed to pharmaceuticals and biotechnology. In this day and age, instruments are essential items for analysis both in and out of laboratories hence stream C was devoted to this theme. The Plenary Lecture of Professor A. F. Fell (Bradford, UK) on ‘Hyphenation Detection Systems in Separation Science’, served to demonstrate the versatility of modern separation methods and of the adeptness of the lecturer in filling the breach left by the billed Plenary Lecturer; Professor D.E. Games having been taken ill. (Conferees wished Professor Games a speedy recovery, and the latest news is that he is to be seen at his desk, and is back in circulation.) Chromatography was the Tuesday morning theme for stream C, followed by the post-lunch poster session on instrumentation and separation science and continuing with the Tuesday afternoon session on separation science. A Change, But Not a Rest At SAC Conferences, Wednesday is traditionally a day for a breather from rushing between one stream and another, and has over the years taken various forms. This time, the day’s events commenced with a Plenary Session on ‘Registration of Analytical Chemists’, with lecture presentations by Dr. J.S. Gow (Secretary General of The Royal Society of Chemistry) on ‘The European Chemist Designation’ and Professor J. D. R. Thomas (Cardiff) on the ‘Indicative Register of Analytical Chemists’. There then followed a broadly based ‘Education Swap Shop’ devoted to novel experiments and teaching ideas, as well as to more diverse matters such as publication in RSC journals and the report of the working group on Education and Training in Analytical Chemistry set up by the Chemical Measurement Advisory Committee (CHEMAC). After an early lunch, everyone boarded coaches for the 150th Anniversary Open Day of the LGC at the impressive new buildings in Teddington.This was a most informative visit relating to the work of the Laboratory and of the facilities available. Some of the conferees took a rush view of the Laboratory in order to attend the CHEMAC Open Meeting in the new lecture room on the site. This meeting, chaired by Dr. R. Worswick, was set to express and discuss the aims and activities of CHEMAC in various terms by: (i) the provision of a forum for the analytical chemistry community to contribute to the development of the Chemical Measurement System; (ii) the dissemination of information on the development of the UK and International Chemical Measurement System; (iii) the establishment and development of a senior level focus to support the development of the Chemical Measurement System; and (iv) the provision of a coordinated UK input concerning the practice of chemical measurement into natio- nal and international organizations. Towards a Fine Ending On Thursday, the full-week conferees saw new faces among them, i.e., a fresh group of two-day registrants (two-day registrations are a feature of SAC arrangements).Further- more, the Plenary Lecturer was not the expected Professor B. R. Kowalski (who was under medical orders not to travel), but his colleague Prgfdsor Jim Callis who, to the intense relief of the Scientific Programme Coordinators, was ‘passing through’ and gave an outstanding lecture on ‘Recent Advances in Analytical Chemometrics’. Atomic spectroscopy has been prominent at analytical conferences ever since Alan Walsh took the Feigl Symposium by storm at Birmingham 30 years ago.It was, therefore, natural that the entire stream A on Thursday and the associated post-lunch posters were devoted to this theme, while stream B stuck to the Plenary Lecture theme of chemometrics to join up with validation matters in the poster presentations. Professor Jim Collis Professor Miguel Valcurcel The current missionary role of the LGC in the realm of method validation, proficiency testing, reference materials, analytical quality assessment and accreditation was well reflected with stream B being devoted to these themes right through from Thursday afternoon to the end of the Scientific Programme on Friday afternoon. On Thursday morning, stream C was devoted to electroanalytical chemistry, and supported by post-lunch posters, after which this stream had sessions on education/professional matters and microanalysis.As already made obvious by the content of stream B, Friday was not to be a dull day, on the contrary there was much of interest. First of all, there was the informative and tightly packed opening Plenary Lecture of Professor M. Valchrcel (Cordoba, Spain) on ‘Flow-through Biochemical Sensors’. Stream A followed this theme throughout the day under the heading of automation and flow injection and shared with spectrometric analysis for the post-lunch posters. The theme of sensors was also prominent on Friday morning in stream C and among the posters after lunch. Forensic methods was the theme for the final Friday afternoon session of stream C . Other Features All SAC Conferences have a Social Programme.The reasons are three-fold. Firstly, to look after accompanying persons so that their partners can give undivided attention to their professional development through the Scientific Programme. On this occasion, there were interesting visits to the Courage Shire Horse Centre in Maidenhead, to Oxford and to the home of the Duke of Marlborough and birthplace of Sir Winston Churchill at Blenheim Palace (and the weather held dry for the open-top bus tour of Oxford), to the Royal Palace at Windsor Castle (a last glimpse ahead of the disastrous fire, which occurred later in the month) and St. George’s Chapel in Windsor, to Blakes Lock Museum in Reading and to the home of the Earl and Countess of Carnarvon at Highclere Castle. The second reason is to provide some insight on science outside of the Conference itself.The Wednesday afternoon visit to the LGC, to which allusion has already been made, catered for this. Additionally, there was a new venture for a SAC Conference, namely the Monday evening Reception at Thames Water Utilities, followed by a tour of their new laboratory in Reading. The official science did not end on this evuing until 22.30 h, but went on unofficially at Whiteknights Hall until much later. The third reason for the Social Programme is to provide an opportunity during the evenings for conferees to discuss and develop the themes of the day’s scientific presentations, and to compare notes on the various approaches to problem solving and the state-of-the-art of analytical chemistry in the wide range of countries represented at the SAC Conference.TheANALYST, JUNE 1993, VOL. 118 67N usual attractions of SAC Conferences and the occasion of the 150th Anniversary Celebration of the founding of the LGC provided the opportunity for collecting together conferees from an unusually wide range of countries and backgrounds. Thus, the receptions already mentioned, along with the Reception of the LGC on Tuesday evening and the Confer- ence Banquet on Thursday evening promoted new friendships amongst those that were previously strangers. Morning and afternoon breaks between lectures were lightened and made informative by the Exhibition stands. A final feature of catering for different tastes was the SAC '92 Update Seminar on Wednesday morning on 'Information Technology for Analytical Chemists' convened by Ms.Cheryl Teague of the RSC Tnformation Services. Conclusion The 150th Anniversary of The Laboratory of the Government Chemist and SAC '92 along with Spectroscopy Across the Spectrum was formally concluded late on Friday afternoon at the Conference Closing Ceremony by Dr. E. J. Newman (President of the Analytical Division of the RSC) and Dr. R. Worswick. All present agreed that this had been a good week for analytical chemistry, but with some sadness that it was at an end. All was not yet finished though, for the Social Sub- committee, mindful that final dispersal of conferees was not to be until Saturday had arranged an evening barbecue, which successfully sealed a memorable week, particularly since the brass band provided various old favourites, including, among others, the English, Welsh and Yorkshire anthems! The last conferees dispersed on the Saturday morning weighed down with their green-covered SAC '92 Conference Handbooks and 150th Anniversary gift book of the LGC entitled 'Weighed in the Balance: A History of the Laboratory of the Government Chemist'. These, and all the other printed information collected and notes taken during the week are the valuable aide memoires on an exercise in the professional development of those who attended. Elsewhere though, as indeed happened at PITTCON '92 in New Orleans in an exercise of The American Board of Industrial Hygiene, conferees would have collected various credit points towards accredited professional advancement. Will this become a feature of SAC Conferences and other organized symposia? J. D. R. Thomas School of Chemistry und Applied Chemistry, The University of Wales, P.O. Box 912, CurdfJ U K CFI 3TB

ISSN:0003-2654    

DOI:10.1039/AN993180065N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JUNE 1993, VOL. 118 69N Conference Diary Date July 4-8 4-9 4-9 11-14 11-15 Conference Location Contact 6th International Conference on Indoor Air Quality and Climate, Indoor Air'93 22nd Meeting of the Federation of European Biochemical Societies Helsinki, Suomi-Finland Stockholm, Sweden Professor Olli Seppanen, SF-02150 Espoo, Finland Dr. Stefan Nordlund, FEBS '93, Department of Biochemistry, Arrhenius Laboratories, Stockholm University, S-10691 Stockholm, Sweden Dr. J. F. Gibson, Secretary (Scientific), The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK WlV OBN Tel: +44 71 437 8656. Fax: +44 71 437 8883 Judith A. Sjoberg, Professional Association Management, 815 Don Gaspar, Sante Fe, NM 87501, USA Tel: + 1 505 989 4735. Fax: + 1 505 989 1073 25th EGAS Secretariat, IS-MRA, Labo.Spectro. Atom., Boulevard Markcha1 Juin, F-14050 Caen, 11th International Meeting on NMR Spectroscopy Swansea, UK 6th International Symposium on Polymer Analysis and Characterization Crete , Greece Caen, France 25th Conference of the European Group for Atomic Spectroscopy France Chemometrics 111, 3rd Czechoslovak Chemometrics Conference Brno, Czechoslovakia Dr. Josef Havel, Department of Analytical Chemistry, Masaryk University, Kotlarska 2, CS- 61137 Brno, Czechoslovakia Tel: +42 5 712984. Fax: +42 5 740108 Miss P. Hutchinson, Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 71 437 8656. Fax: +44 71 734 1227 Dr. D. Stevenson, Robens InstituteKhemistry Department, University of Surrey, Guildford, Surrey, UK GU2 5XH Fax: +44 483 503517 Professor D.Brinkmann, Physik-Institut, University of Zurich, Schonberggasse 9, CH-8001 Zurich, Switzerland Robert L. Wershaw, U.S. Geological Survey, P.O. Box 25046 MS 408, Denver, CO, USA Tel: +1 303 467 8280. Margaret Ridgell, AOAC, 2200 Wilson Boulevard, Suite 400, Arlington, VA 22201-3301, USA 1-15 2-14 9-21 R & D Topics Meeting 1993 Bradford, W. Yorkshire, UK 6th Symposium on Handling of Environmental and Biological Samples in Chromatography Guildford, Surrey, UK 19-23 26-29 26-29 12th International Symposium on Nuclear Quadrupole Interactions Zurich, Switzerland 35th Rocky Mountain Conference on Analytical Chemistry Denver, CO, USA 107th AOAC International Annual Meeting and Exposition Washington, DC, USA August 9-11 3rd Soil and Sediment Residue Analysis Workshop Winnipeg, Manitoba, Canada Dr.G. R. Barrie Webster, Pesticide Research Laboratory, Department of Soil Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2. Tel: +1 204 474 6039. Fax: +1 204 275 6019; or Professor Dr. Joseph Tarradellas, IGE, Federal Technical Institute EPF-L, CH-1015 Lausanne Ecublens, Switzerland Professor Erkang Wang, Asianalysis 11, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, P.O. Box 1022, Changchun, Jilin 130022, China Tel: +86 431 682 801 (ext. 562). Fax: +86 431 685 653 Professor Douglas Hamilton, Physics Department, 2152 Hillside Road, University of Connecticut, Storrs, CT 06269-3046, USA Dr. R. A. Ettlin, EUROTOX Secretary General, Sandoz Pharma Ltd., Toxicology, Building 881, P.O. Box, CH-4002 Basle, Switzerland 9-13 Asianalysis 11: Second Asian Conference on Analytical Chemistry Changchun, China 9-13 ILC '93: International Conference on Luminescence and Optical Spectroscopy on Condensed Matter Storrs, CT, USA 22-25 EUROTOX'93 (32nd Congress of Toxicology) Uppsala, Sweden70N ANALYST, JUNE 1993, VOL. 118 Date 22-27 22-27 22-27 23-27 23-27 23-27 23-27 26119 29-319 30-119 30-219 30-419 31-119 Conference Location Gordon Research Conference on Reactive Polymers, Ion-exchangers and Adsorbents USA Newport, RI, 206th ACS National Meeting (with Sessions of Chicago, IL, the Divisions of Analytical Chemistry, Environmental Chemistry, Chemical Health and Safety, etc.) Third International Symposium on Separation Technology 9th Meeting of EURO CVD 9th International Conference on Fourier Transform Spectroscopy 6th Hungaro-Italian Symposium on Spectrochemistry , Advances in Environmental Sciences 9th Danube Symposium on Chromatography 5th International Conference on Electron Spectroscopy 9th International Symposium: Advances and Application of Chromatography in Industry 15th International Symposium on Safety in Interaction with Quality, Productivity and Economy Second European Symposium on Near Infrared Spectroscopy USA Antwerp, Belgium Tampere, Finland Calgary, Alberta, Canada Lillafiired, Hungary Budapest , Hungary Kiev, Ukraine Bratislava, Czechoslovakia Lugano , Switzerland Kolding, Denmark 13th European Conference on Surface Science Warwick, UK 106th Annual International Meeting and Exposition of AOAC International September 2-3 2nd UK International Meeting on Biological and Biomedical Applications of Scanning Probe Microscopy 5-1 0 Ninth International Biodeterioration and Biodegradation Symposium 5-10 5th European Conference on the Spectroscopy of Biological Molecules 5-1 1 Euroanalysis VIII: European Conference on Analytical Chemistry Prague, Czechoslovakia Nottingham, UK Leeds, UK Lontraki, Greece Edinburgh, UK Contact Professor Cs.Horvath, Department of Chemical Engineering, Yale University, P.O. Box 2159, Yale Station, New Haven, CT 06520, USA Tel: + 1 203 432 2217. Fax: + 1 203 432 4360 Mr. B. R. Hodson, American Chemical Society, 115516th Street N.W., Washington, DC 20036, USA Tel: + 1 202 872 4396.Mrs. M. Stalmans, University of Antwerp (UTA), Department of Chemistry, Universiteitsplein 1, B- 2610 Antwerp-Wilrijk, Belgium Tel: +32 3 820 23 75. Fax: +32 3 820 23 74 Ms. Raili Siekkinen, Tampere University of Technology, P.O. Box 527, SF-33101, Tampere, Finland Lois Kokoski, Conference Office, The University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4 Tel: + 1 403 220 5051. Fax: + 1 403 284 5696 Dr. Gy. Zhray, Institute of Inorganic and Organic Chemistry, Eotvos University, P.O. Box 32, H- 1518 Budapest 112, Hungary Professor L. Szepesy, Hungarian Chemical Society, Budapest, Hungary Tel: +36 1 186 9000. Fax: +36 1 181 2755 J. J. Pireaux, LISE, rue de Bruxelles, 61, B-5000 Namur, Belgium Assoc. Prof. Jozef Polonsky, Department of Analytical Chemistry, Slovak Technical University, Radlinskkho 9, 812 37 Bratislava, Czechoslovakia Tel: +42 7 560 43.Fax: +42 7 49 31 98 Secretariate ISSA, Section Chemistry, c/o BG Chemie, P.O. Box 10 14 80, D-W-6900 Heidelberg 1, Germany Lone Vejgaard, Biotechnological Institute , Holbergsvej 10, P.O. Box 818, DK-6000 Kolding, Denmark Tel: +45 75520433. Fax: +45 75529989 Dr. C. F. McConville, ECOSS-13, Department of Physics, University of Warwick, Coventry, UK CV4 7AL Tel: +44 203 523353. Fax: +44 203 692016 J. Barek, Department of Analytical Chemistry, Charles University, Albertov 2030, 12840 Prague 2, Czechoslovakia Tel: +42 2 292051, +42 2 297541. Fax: +42 2 291958 The SPM Laboratory, Department of Pharmaceutical Sciences, University of Nottingham, Nottingham, UK NG7 2RD Tel: +44 602 515101. Fax: +44 602 515102 The Conference Secretary (RE), Department of Chemical Engineering, The University of Leeds, Leeds, UK LS2 9JT Professor Th.Theophanides, National Technical University of Athens, Department of Chemical Engineering, Zogratou 15780, Athens, Greece Miss P. E. Hutchinson, Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 71 437 8656. Fax: +44 71 734 1227ANALYST, JUNE 1993, VOL. 118 7 1N Date 5-10 5-1 1 6-10 6-10 6-10 6-10 7-8 7-10 7-12 8-10 8-1 1 9-15 11-15 12-17 13-17 13-17 19-22 19-22 Conference Location Second International Conference on the Biogeochemistry of Trace Elements Taipei, Taiwan, Republic of China Pharmacy World Congress '93 Tokyo, Japan 18th International Conference on Infrared and Millimetre Waves UK Colchester , Defect Recognition and Image Processing in Santander, Semiconductors and Devices Spain 11th Specialised Colloque Ampere on Menton, Magnetic Resonance in Homogeneous and France Heterogeneous Cat a1 y sis Second International Conference on Magnetic Heidelberg, Resonance Microscopy Germany Environmental Fate of Chemicals Lancaster , UK 12th International Symposium on Biomedical Applications of Chromatography and Electrophoresis and 2nd International Symposium on the Applications of HPLC in Enzyme Chemistry 12th International Symposium on Cordoba, Microchemical Techniques Spain Verona and Soave, Italy 4th Workshop on Chemistry and Fate of Modern Pesticides and Related Pollutants Prague, Czechoslovakia 14th International Symposium on Polynuclear Tan-Tar- A, MO, Aromatic Hydrocarbons USA ISEC '93, International Solvent Extraction York, Conference: Solvent Extraction in the Process UK Industries EIRELEC 1993: Electrochemistry to the year Adare, Co.2000 Limerick, Ireland 9th International Conference on Heavy Toronto, Metals in the Environment Canada International Conference on Nuclear Prague, Analytical Methods in the Life Sciences Czechoslovakia Workshop in Liquid Scintillation Counting Loughborough , Leicestershire, UK 4th International Symposium on Chiral Discrimination Quebec, Montreal, Canada 2nd National Symposium on Planar Chromatography: Modern Thin-Layer Triangle Park, Research Chromatography NC, USA Contact Dr. Shang-Shyng Yang, Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan 106, Republic of China; or Dr.Domy C. Adriano, University of Georgia, Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA Professor D. J. A. Crommelin, FIP Congress Department, The Hague, The Netherlands Tel: +31 70 363 1925. Fax: +3170 363 3914 Professor T. J. Parker, Department of Physics, University of Essex, Wivenhoe Park, Colchester, UK C04 3SQ Dr. Juan Jimknez, Drip 5, Universidad de Valladolid, 47011 Valladolid, Spain Professor J. Fraissard, Laboratoire de Chimie des Surfaces, Universitd P. et M. Curie, 4, Place Jussieu (Boite 196), 75252 Paris Cedex 05, France Dr. Bernhard Blumich, c/o Max Planck-Institute fur Polymerforschung, Postfach 3148, D-6500 Mainz, Germany Dr.D. Osborn, Institute of Terrestrial Ecology, Monks, Abbots Ripton, Huntingdon, UK PE17 2LS Dr. Franco Tagliaro, Scientific Secretariat, c/o lstituto di Medicina Legalc, Policlinico Borgo Roma, 1-37134 Verona, Italy Tel: +39 45 8074 618. Fax: +39 45 505 259 Professor M. Valcarcel, Quimica Analitica, Facultad de Siencias, 14004 Cordoba, Spain Tel: +34 57 234453. Fax: +34 57 452285 M. Frei-Haiisler, IAEAC, P.O. Box 46, CH-4123 Allschwil 2, Switzerland Tel: +41 61 632789. Fax: +41 61 482 08 05 Professor E. Cavalieri, Epply Institute, Medical Center, University of Nebraska, Omaha, NE Tel: +1402 559 4090. Fax: +1402 559 4651 Conference Secretariat, SCI, 14/15 Belgrave Square, London, UK SW1X 8PS Tel: +44 71 235 3681. Fax: +44 71 823 1698 Professor M.R. Smyth, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland Tel: +353 17045308. Fax: +353 17045503 Heavy Metals Secretariat, CEP Consultants Ltd., 26-28 Albany Street, Edinburgh, UK EH1 3QH Tel: +44 31 557 2478. Fax: +44 31 557 5749 Jan Kucera, Nuclear Research Institute, CS-250 68 Rez near Prague, Czechoslovakia Tel: +42 2 685 7831 ext. 2268. Fax: +42 2 685 7567 Dr. Peter Warwick, Nuclear Chemistry Laboratories, Loughborough University of Technology, Loughborough, Leicestershire, UK LE113TU Tel: +44 509 222585. Fax: +44 509 233163 Chiral Secretariat, Conference Office, McGiIl University, 550 Sherbrooke St. West, West Tower, Suite 490, Montreal, Quebec, Canada H3A 1K9 Tel: +1 514 398 3770. Fax: +1514 398 4854 Ms. Janet E. Cunningham, Barr Enterprises, P .0 Box 279, Walkersville, MD 21793, USA Tel: +1301898 3772. Fax: +1301898 5596 68198-6805, USA72N ANALYST, JUNE 1993, VOL. 118 Date 20-24 20-26 21-22 21-23 22-24 Conference Location Dioxin 93: 13th International Symposium on Chlorinated Dioxins and Related Compounds Vienna, Austria 173rd Annual Meeting of the Swiss Academy of Natural Sciences (including Symposia of the Swiss Society for Analytical and Applied Chemistry, the Swiss Society for Microchemistry and Instrumental Analysis, the Swiss Association on Environmental Research, and other Societies, in German and French) 4th German Symposium on Near Infrared Spectroscopy Germany CH-1936 Bagnes-Verbier , Switzerland Essen, The Royal Society of Chemistry 1993 Autumn Wanvick, Meeting UK XIIth Conference of Analytical Chemistry of Romania Romania Constanta, Contact Symposium Secretariat, Dioxin '93, Gesellschaft Osterreichischer Chemiker, Nibelungengasse 11, A-1010 Vienna, Austria Tel: +43 222 587 3980/4249.Fax: +43 222 587 8966 General Secretary, Swiss Academy of Sciences, Barenplatz 2, P.O. Box 2535, CH-3001 Berne, Switzerland Professor Dr. H. W. Siesler, University of Essen, Schutzenbahn 70, P.O. Box 103764, D-4300 Essen 1, Germany Miss P. E. Hutchinson, Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 71 437 8656. Fax: +44 71 734 1227 Dr. Gabriel-Lucian Radu, The Romanian Society of Analytical Chemistry, 13 Bul.Caro1 I, Sector 3, 70346 Bucharest, Romania 26-1/10 1993 European Workshop in Chemometrics Leuven, Timshel Conference Service, J.B . Van Monsstraat Belgium 4, B-3000 Leuven, Belgium Tel: +32 16 290010. Fax: +32 16 290510 26-1/10 12th Australian Symposium on Analytical Perth, Valerie Landgrebe, Symposium Secretariat, 12AC/ Chemistry incorporating 3rd Environmental Australia 3EC, Conference and Seminar Management, Chemistry Conference UWA Extension, The University of Western Australia, Nedlands, Perth, Western Australia 6009, Australia Tel: +61 9 380 3181/2433. Fax: +61 9 380 1088/1066 Dr. Paul Illing, Health and Safety Executive, R425 Magdalen House, Stanley Precinct, Bootle , UK L20 3QZ Tel: +44 51 951 3420. Fax: +44 51 922 7918 30 Duration of Repeated Dose Toxicity Studie- Bath, A Commonsense Approach? UK October 4-8 5-7 5-7 5-8 10-15 11-13 ECASIA 93, 5th Conference on Application of Surface and Interface Analysis 34th ORNL-DOE Conference on Analytical Chemistry in Energy Technology Laboratory Exhibition and Conference 5th Meeting of the Nuclear Magnetism and Biology Group Electrochemical Society Meeting VIth National Symposium on Mass Spectometry Catania , Italy Gatlinburg, TN, USA London , UK Toulouse, France New Orleans, LA, USA Dehradun, India G.Marletta, Consorzio Catania Ricsrche, V. Le Andrea Doria, 6, 1-95125 Catania, Italy Tel: +39 95 221635. Fax: +39 95 339734 W. R. Laing, Technical Program Chairman, Oak Ridge National Laboratory, P.O. Box '2008, MS 6127, Oak Ridge, TN 37831-6127, USA Tel: +1615 574 4852. Fax: +1 615 574 4902 Evan Steadman Communications Group Ltd., 90 Calverley Road, Tunbridge Wells, Kent, UK TN12UN Professor M.Malet-Martino, Laboratoire IMRCP, Universite Paul Sabatier, 118, route de Narbonne, F-31062 Toulouse Cedex, France Electrochemical Society Inc, 10 South Main Street, Pennington, NJ 08534-2896, USA Dr. Pradeep Kumar, Indian Institute of Petroleum, Dehradun-248 005, India, and Dr. S. K. Aggarwal, Honorary Secretary-ISMAS, c/o Fuel Chemistry Division, Bhabha Atomic Research Centre, Bombay-400 085, Maharastra, IndiaANALYST, JUNE 1993, VOL. 118 73N Date 13 16-17 17-21 17-22 18-22 19-23 20-22 21-22 Conference FT Microscopy-10 Years On: 4th European Seminar on FT-IR Microscopy Second National Conference on Inductively Coupled Plasma Mass Spectrometry Eighth Symposium on Separation Science and Technology for Energy Application FACSS XX, 20th Annual Meeting of the Federation of Analytical Chemistry and Spectroscopy Societies Modern Electrochemistry in Industry and for the Protection of the Environment EXPOQUIMIA '93: Applied Chemistry Technical Fair Hygiene and Health Management in the Working Environment International Conference on Analytical Chemistry, Biochemistry and Pharmaceutical Sciences November 1-3 2 7-10 7-1 1 7-12 11-12 14-19 14-19 Chernyaev Conference on Chemistry, Analysis, Technology and Application of Platinum Metals Electro-Membrane Processes Electrophoresis '93 7th International Forum-Electrolysis in Chemical Manufacture Symposium on Supercritical Fluid Phenomena (1993 Annual Meeting of the AIChE) International Conferences on Analytical Chemistry, Biochemistry, Pharmaceutical Sciences, and Water QualitylEnvironmentaI Pollution XV International Congress of Clinical Chemistry OPTCON '93 Location Manchester , UK Detroit, MI, USA Oak Ridge, TN, USA Detroit, MI, USA Krakow, Poland Barcelona, Spain Ghent, Belgium Casablanca, Morocco Moscow, Russia London, UK Charleston, SC, USA Lake Buena Vista, FL, USA St.Louis, MO, USA New Delhi, India Melbourne, Australia San Jose, CA, USA Contact Michelle Barker, Conference Co-Ordinator, Spectra-Tech Europe Limited, Genesis Centre, Science Park South, Birchwood, Warrington, UK WA3 7BH Tel: +44 (0) 925 830 250. Fax: +44 (0) 925 830 252 Society for Applied Spectroscopy/ICP/MS Users Group, 198 Thomas Johnson Drive, Suite-2, Frederick, MD 21702-4317, USA Tel: +1301 694 8122. J. T. Bell, Oak Ridge National Laboratory, Post Office 2008, Oak Ridge, TN 37381, USA FACSS, 198 Thomas Johnson Drive, Suite S-2, Fredericks, MD 21702, USA Tel: +1301846 4789.Fax: +1 301 694 6860 Dr. Andrzej Kowal, Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapiminajek 1, 30-239 Krakow, Poland Fira de Barcelona, Avda. Reina Ma Cristina, 08004 Barcelona, Spain 3rd International Symposium, 'Hygiene and Health Management in the Working Environment', c/o T1- K VIV, Attn. Ms. Rita Peys, Desguinlei 214, B- 2018 Antwerp, Belgium Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5V7 Tel: +1 613 932 7702. Dr. I. B. Baranovsky, Kurnakov Institute of General and Inorganic Chemistry, 31 Lenin Avenue, Moscow 117907, Russia Dr.T. R. Ralph, Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading, Berkshire, UK RG4 9NJJ Tel: +44 734 722811 ext. 2257. Fax: +44 734 723236 Mrs. Janet Cunningham, Electrophoresis '93, c/o The Electrophoresis Society, P.O. Box 279, Walkersville, MD 21793, USA Tel: +1301 898 3772. Fax: +1301898 5596 Dr. N. Weinberg, 72 Ward Road, Lancaster, NY Tel: +1716 684 0513. Fax: +1 716 684 0511 Michael A. Matthews, Chemical Engineering Department, University of Wyoming, Box 3295, University Station, Laramie, WY 82071-32, USA Tel: +1 307 766 5769 Fax: +1 307 766 4444. Or: Ted W. Randolph, Chemical Engineering Department, Yale University, 9 Hillhouse Avenue, New Haven, CT 06520-2159, USA Tel: +1203 432 4375. Fax: +l 203 432 7232 Dr. V. M.Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5V7 Tel: +1613 932 7702. 1993 IFCC Congress Secretariat, 232 Bridge Road, Richmond, Victoria, Australia Tel: +61 3 429 4322. Fax: +61 3 427 0715 IEEELEOS, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ 08855-1331, USA Tel: +1908 562 3896. Fax: +1908 562 1571 14086-9779, USA74N ANALYST, JUNE 1993, VOL. 118 Date Conference Location Contact 15-19 32nd Annual Eastern Analytical Symposium New Jersey, EAS Program Committee, P.O. Box 633, 22-23 International Conferences on Analytical Shanghai, Dr. V. M. Bhatnagar, Alena Chemicals of Canada, USA Montchanin, DE 19710-0633, USA Chemistry, Biochemistry, Pharmaceutical China P.O. Box 1779, Cornwall, Ontario, Canada Sciences, and Water Quality/Environmental Pollution K6H 5V7 Tel: +1 613 932 7702.December 7-9 The First Conference in Chemistry and its Doha, Applications Qatar 8-10 Laser M2P, Materials Engineering, Medicine Lyon, and Biology, Physics and Chemistry France Professor Abdel-Fattah M. Rizk, Department of Chemistry, Faculty of Science, University of Qatar, P.O. Box 2713, Doha, Qatar Richard MoncorgC, Universitk de Lyon 1, B2t. 205, F-69622 Villeurbanne Cedex, France 1994 January 10-15 1994 Winter Conference on Plasma San Diego, CA, Dr. R. Barnes, 1994 Winter Conference on Plasma - Spectrochemistry USA February 21-25 OFC '94: Optical Fibre Communications San Jose, CA, Conference USA 22-25 HTC 3: Third International Symposium on Antwerp, Hyphenated Techniques in Chromatography Belgium 28-43 Pittcon '94: The 45th Pittsburgh Conference Chicago, IL, USA and Exhibition on Analytical Chemistry and Applied Spectroscopy April 6-8 Electroanalysis: A Tribute to Professor Cardiff, J.D. R. Thomas UK 10-15 207th ACS National Meeting and 5th Mexico City, Chemical Congress of North America (with Sessions of Analytical Chemistry, Environmental Chemistry, Chemical Health and Safety, etc.) Mexico 12-14 13th Pharmaceutical Technology Conference Strasbourg, France 19-22 ANALYTICA'94: 14th International Munich, Conference on Biochemical and Instrumental Analysis Germany Spectrochemistry , % ICP Information Newsletter, Department of Chemistry, Lederle GRC Towers, University of Massachusetts, Amherst, MA 01003- 0035, USA Tel: +1 413 545 2294. Fax: +1413 545 4490 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, Tel: + 1 202 223 9034. Fax: + 1 202 416 6100 Dr. R. Smits, p/a BASF Antwerpen N.V., Central Laboratory, Scheldelaan, B-2040 Antwerp, Belgium Tel: +32 3 568 2831. Fax: +32 3 568 3250 Mrs. Alma Johnson, Program Secretary, The Pittsburgh Conference, Department CFP, 300 Penn Center Boulevard, Suite 332, Pittsburgh, PA 15235, USA DC 20036-1023, USA Dr. J. M. Slater, Department of Chemistry, Birkbeck College, University of London, 29 Gordon Square, London, UK WClH OPP Tel: +44 71 380 7474. Fax: +44 71 380 7464 Mr. B. R. Hodson, American Chemical Society, 1155-16th Street N.W., Washington, DC 20036, USA Tel: +1 202 872 4396. Professor Mike Rubinstein, 13th Pharmaceutical Technology Conference, 24 Menlove Gardens North, Liverpool, UK L18 2EJ Tel: +44 51 737 1993. Fax: +44 51 737 1070 Munchener Messe- und Ausstellungsgesellschaft mbH, Analytica '94lWerbung Postfach 12 10 09, D-8000 Munchen 12, Germany Tel: +49 89 51 07 143. Fax: +49 89 51 07 177 Entries in the above listing are at the discretion of the Editor and are free of charge. If you wish to publicize a forthcoming meeting please send full details to: The Analyst Editorial Office, Thomas Graham House, Science Park, Milton Road, Cambridge, UK CB4 4WF. Tel: +44 (0)223 420066. Fax: +44 (0)223 420247.

ISSN:0003-2654    

DOI:10.1039/AN993180069N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JUNE 1993, VOL. 118 75N ~ ~~ Book Reviews Making Light Work: Advances in Near Infrared Spectro- scopy Edited by Ian Murray and Ian A. Cowe. Pp. xiii + 652. VCH. 1992. Price f98.00. ISBN 3-527-28498-2 (VCH, Weinheim); 1-56081-264-8 (VCH, New York). The World of Peptides. A Brief History of Peptide Chemistry By Theodor Wieland and Miklas Bodansky. Pp. xiv + 298. Springer-Verlag. 1991. Price DM198.00. ISBN 3-540- 52830-X. During the past 50 years spectroscopic techniques have proliferated with amazing speed and have proved exceedingly valuable, for fundamental studies and in an analytical context. Predictably, there has been the tendency to look for even more esoteric extensions of current practice, involving more refined theoretical concepts and advanced technological resources.In these circumstances it is easy to overlook what can be achieved by more modest approaches, and near- infrared spectroscopy provides an excellent example. The number of publications in this field was about 24 by about 1970 but, 20 years later, it had passed the 3000 mark. This explosive growth is the result of three factors: simple, reliable and relatively inexpensive instrumentation; the harnessing of chemometric techniques for data interpretation; and a com- prehension of the analytical potential of the technique. Not surprisingly, this high level of activity has prompted international conferences and the present volume documents 98 presentations at the fourth such conference, held in Aberdeen, UK, in August 1991. The Editors and Publisher are to be congratulated on having assembled this large amount of technical information in a clear and rational form, so quickly.It will be of considerable value, not only to analysts, but also to scientists and technologists of various disciplines. It is recommended unreservedly. The 98 contributions are grouped into subject areas. First are those relating to instrumentation. They cover spec- trometer stability and measurement precision, the trans- ferability of data, calibration standards and fast scanning instruments providing process control data. Included here, also, are a few contributions dealing with background topics, such as the information content of hydrocarbon spectra and the effect of water on the spectra of model compounds. The important role of chemometric techniques in data processing emerges clearly in the next group of papers.They include accounts of the partial least squares method, principal component analysis, segmented calibrations and neural networks. They provide an excellent assessment of the current position. The remainder of the book, some 70%, covers the many and varied applications; these can only be touched upon in this brief survey. There is a valuable review of the use of the technique in agriculture, and specific applications reported are as diverse as soil analysis, the nutritive value of herbage and silage and the viability of wheat seeds. A review of appli- cations in the food industry is followed by specific studies, which include the control of fermentation, the authentication of orange juices, the determination of whey in milk powder and the heat treatment of meat.A range of applications in industrial analysis and process control is presented, including the control of a steam cracker, the determination of cotton maturity, the analysis of cellulosic fibre blends, the composition of wood, the study of polymer melt processes and thickness measurements on polymer films. The final group of papers covers pharmaceutical and medical applications. The analysis of pharmaceutical raw materials is thoroughly discussed and, for the medical analyst, the topics include the monitoring of blood during storage, moisturiza- tion in skin and the perinatal monitoring of cerebral oxidative metabolism. W. F. Maddams In writing this brief account, the authors set out to present ‘the history of peptide chemistry as a continued human effort towards lofty goals’ (such as Nobel prizes?) and ‘to provide entertaining reading for the experienced researcher and some stimulus for the uninitiated!’.What follows is a very readable if somewhat subjective account of the important develop- ments in peptide chemistry and biochemistry over the last 100 years, and the personalities involved. One has to be fairly familiar with the science, however, to get the best from the narrative. The first half of the book primarily concerns chemical discoveries and progress. It is prefaced by a resum6 of amino acid and peptide chemistry in general, which is probably too sketchy to be of much use to novices. Subsequent, more substantial material deals with the early synthesis of peptides and the rivalry between Curtis and Fischer, the Bergmann era and the evolution of protecting groups and chromatography, the development of coupling procedures, solid phase (Merri- field) syntheses and finally structure elucidation. The second half of the book focuses on the discovery, structural elucida- tion, synthesis and function of bioactive materials, under headings of peptide hormones, protein fragments and micro- organisms and fungi.Compounds such as oxytocin, insulin, gastrin, angiotensin, venoms, antibiotics and toxins, are described individually, linking discovery, evidence and deduc- tion with biographical detail. The final chapter looks at the geographical distribution of peptide research through the years, which seems an odd way to legitimize the title. A more useful appendix contains biographies not given in the main text.The authors do a good job of following events leading to a major discovery but communicate little of the excitement or anxiety surrounding it. They also achieve a comfortable balance between the scientific detail and biographical back- ground. The outcome is an interesting book describing many successes and a few near-misses. It will appeal to any chemist or biochemist working with peptides with space on the coffee table if not the bookshelf. Brian C. Challis Chemometrics. Applications of Mathematics and Statis- tics to Laboratory Systems By Richard G. Brereton. Ellis Horwood Series in Chemical Computation, Statistics and Information. Pp. 307. Ellis Horwood.1990. Price $45.00. ISBN 0-1 3-1 31 350-9. In the fifteen or so years that chemometrics has been available to chemists it has developed from a fringe subject studied by a few ‘odd-balls’ to a widely accepted set of tools routinely used in many applications, at least within the sphere of analytical chemistry. Two measures of this development are the number of educational institutions teaching chemometrics as a special- ist subject or as part of a mainstream chemistry course. Richard Brereton is one of the UK academics who has been at the front of bringing chemometrics to its current status and this book captures much of his work and interests in his own inimitable style.76N ANALYST, JUNE 1993, VOL. 118 The seven chapter headings are more or less what would be expected for a chemometrics text aimed at the laboratory researchedchemist: lntroduction (15pp.), Experimental Design (57pp.), Sampling in Sequential Series (24pp.), Optimisation of Analytical Conditions (42pp.) , Univariate Signal Processing (46pp .) , Multivariate Signal Processing (26pp.) and Pattern Recognition (56pp.).A constant theme in the chapters is time series data and many of the examples on how to use particular techniques are based on them. This approach gives a useful insight into what information can be extracted from data by the different techniques. Unfortunately, one effect is that some subjects, such as Fourier transforms and autocorrelation, are treated in some depth whereas others, such as principal components regres- sion and partial least squares, are covered in a few lines.The reader is referred to a bibliography for more information, which, for all chapters, is reasonably comprehensive. Accepting this limitation, the text does contain many useful observations on, and descriptions of, techniques that the experienced user as well as the novice could usefully revise. It also includes comment on some subjects not normally found in texts on chemometrics: maximum entropy, fuzzy methods and information theoretic methods. The seven appendices are squeezed into only seven pages. Of the seven, the last four are the most useful as they are descriptions of the algorithms required for principal com- ponents analysis, linear discriminant analysis, the NIPALS algorithm and partial least squares. Overall, the book is one to have in the armoury of chemometrics texts. It complements most other texts with its focus on sequential data but it is not sufficiently comprehen- sive in its coverage of mainstream multivariate methods to stand alone.Novices will find it fairly easy to follow and are encouraged to replicate the examples on their own computer systems. The experienced chemometrician will find some useful parts and interesting comments. R . L. Tranter lmmunoassays for Trace Chemical Analysis. Monitoring Toxic Chemicals in Humans, Food and the Environment Edited by Martin Vanderlaan, Larry H. Stanker, Bruce E. Watkins and Dean W. Roberts. ACS Symposium Series 457. Pp. x + 374. American Chemical Society. 1991. Price US$79.95. ISBN 0-841 2-1 905-2. This volume is part of the American Chemical Society Symposium Series and is developed from a Symposium sponsored by the International Chemical Congress of the Pacific Basin Societies held in Hawaii in 1989.Owing to the increasing public disquiet concerning environmental pollu- tion, exposure to harmful chemicals and food quality and safety, particularly with respect to additives and contami- nants, there have been ever-increasing demands on regulatory bodies to undertake more sampling and analysis for an ever- increasing diversity of chemicals. This book examines the use of immunoassay methods as an alternative to the more traditional chemical techniques for performing this much needed quality control. It encompasses a wide range of applications for immunoassay including natural toxicants, particularly mycotoxins, chemical residues, particularly pesticides and herbicides, in food and the environment and the monitoring of human exposure to toxic chemicals.The volume is divided into three sections and each begins with an instructive review identifying the major points of issue in that particular section. There are also three appendices, which provide an up-to-date collection of references arranged in accordance with the application, i.e., environmental monitoring, mycotoxin analysis and human exposure monitor- ing. Inevitably, as one would expect, with a symposium volume of this sort there are omissions such as, for example, drug residues in animal products. Nevertheless, the topics covered are impressive, which together with the reasonably low price, provide a strong recommendation of the book for the analytical chemist and epidemiologist.Bryan D. Jones Advanced Surface Coatings. A Handbook of Surface Engineering Edited by D. S. Rickerby and A. Mathews. Pp. xiii + 368. Blackie. 1991. Price f75.00. ISBN 0-21 6-92899-0. As the title implies this book covers modern techniques of deposition on surfaces such as the use of plasmas in ion implantation, evaporation, sputter deposition, plasma-assis- ted physical vapour deposition, thermally activated and plasma-assisted chemical vapour deposition, thermal spraying and laser surface treatment as well as the characterization and the evaluation of these coatings. The final chapter looks briefly at the market perspective and future trends and also very briefly discusses ‘solution state processes’ t.e. , electrode- less and electropulse plating, composite electroplating and sol-gel processing. There is no doubt that the book is a comprehensive survey of the advanced techniques used in the technology of surface coating and each chapter includes the theory of the process as well as the practical aspects, is well supported by references and includes a section on the application of the techniques described, although most of these appear to be in the aerospace industry. From the point of view of the analyst the techniques described in the chapters on characterization and evaluation of the coatings are all spectroscopic and range from photoelec- tron spectroscopy to particle-induced X-ray emission. As with the techniques of deposition a brief description of the theory of the technique is given.In all the book is well produced and the Editors should be congratulated on compiling a comprehensive survey of the field, my only quibble would be with the sub-title of the book ‘A Handbook of Surface Engineering’, which to my mind implies a wider field than is covered by this book. A . H . Chapman Food Contaminants: Sources and Surveillance Edited by Colin S. Creaser and Rupert Purchase. Pp. viii + 206. The Royal Society of Chemistry. 1991. Price f47.50. ISBN 0-85186-606-9. This book stems from two symposia arranged by The Royal Society of Chemistry on food contamination, held in London in April 1989 and May 1990. The topic of food contamination is broadly divided into food-chain contaminants (fungal metabolites, environmental contaminants, etc.) and food- production contaminants (compounds of ‘man-made’ origin).This is a somewhat arbitrary distinction as the food chain is very much a continuum of production and processing. Chapter 1 is a review of natural toxicants in foods, e.g., saponins, glucosinolates, etc. which are not really contami- nants at all. This is in contrast to Chapter 2, which deals with the very important group of environmental contaminants, the chlorinated dioxins and furans. Similarly Chapter 3 covers pol yaromatic hydrocarbons, how they find their way into foods and their toxicological significance. Chapter 4 seems to be used to set the scene for the rest of the book, and is on food-production contaminants, pesticide residues, packaging residues etc., and the work of the regulatory authorities in this area., The next six chapters areANALYST, JUNE 1993, VOL.118 77N divided between contaminants from contact materials (Chapt- ers 6 and 7), drug residues (Chapters 7 and 8), pesticides in drinking water (Chapter 9) and finally unwanted flavours (Chapter 10). This is an extremely heterogeneous collection of papers both in terms of topic and depth of treatment. Martin Shepherd’s chapter on veterinary drug residues contains a wealth of analytical detail on a broad spectrum of compounds, whereas the other contributions are less detailed. As an example this chapter cites 293 references whereas the other 5 chapters can only manage 125 references between them. This book provides a very selective, and variable, coverage of food contaminants.No reference to heavy metals, non- permitted dyes, nitrosamines, to mention a few topics, can be found between its covers. It is surprising that two symposia could only raise 10 chapters, one assumes that some of the speakers did not write. The style is not consistent throughout and the citation of references in the first chapter is positively bizarre, e.g., Cherion et al., 1983s. With only 200 pages of text this book is not good value at 247.50. The RSC have produced some superb books at very reasonable prices, but this is not one of them. Some of the contributions are excellent but the pricing strategy adopted will ensure they receive only a limited readership. R. Macrae HPLC of Peptides and Polynucleotides.Contemporary Topics and Applications By Milton T. W. Hearn. Pp. xv + 776. VCH. 1992. Price DM225.00. ISBN 1-89573-295-5 (VCH Publishers); 3-527- 26951 -7 (VCH Verlagsgesellschaft). This book is number two in a new series entitled ‘Analytical Techniques in Clinical Chemistry and Laboratory Medicine’. In his preface, the series editor, Gary D. Christian states the goal of the series to be ‘. . . to present analytical methods and techniques that are used to determine and characterize medically relevant substances, and to cover specific problems of current interest’. He continues, ‘Emphasis is on the techniques and procedures and interpretation of results obtained, with adequate theory only for understanding of the fundamentals of a particular technique’.Without doubt, the application of high-performance liquid chromatography (HPLC) in its various guises is covered extensively, however, this is not a book for the occasional user of HPLC. Rather, it is a comprehensively written and well-referenced book that will find its natural place upon the bookshelves of the dedicated analytical chemist who wishes to learn more of the theoretical and practical aspects of HPLC. Milton Hearn is one of the leading practitioners in the development of chromatographic techniques and their reduc- tion to practice in the separation and analysis of amino acid derived biomolecules. In addition to his own, not inconsider- able, contribution to this volume, Milton Hearn has as- sembled an impressive collection of contributions from leading exponents in the field of HPLC and, consequently, has managed to comprehensively cover the many techniques and procedures applicable to biomolecular chromatographic sep- aration.The book opens with an excellent general introduction by Hearn to the basic concepts of chromatography, the variety of ways in which these may be applied, together with a consideration of the physical criteria upon which the tech- niques rely. Practical considerations commence with a chapter covering various aspects of sample presentation and column hygiene including a detailed discussion on sample prepara- tion. Column maintenance and repair is covered in some detail and includes protocols that will prove of use in the guidance of both novice and experienced operator alike. Silica-based packing materials are given a detailed introduc- tion with the design, preparation, and characteristics of bonded silicas, and their application to the various forms of HPLC, being discussed.Also included is an extensive listing of products, their properties and various sources of supply. Subsequent chapters cover agarose and polyethyleneimine based media in a similar way. The emphasis of the book then changes to that of application with chapters on the use of high-performance, ion- exchange, reversed phase, hydrophobic interaction, size exclusion, dye ligand and affinity chromatography to the separation of peptides and proteins. Also included is a chapter on the use of complex multi-modal stationary phases, that being those sensitive to changes due to the presence of multiple functionality.The many factors influencing such an approach and its application are considered at some length. Special consideration is given within these overviews to the factors influencing chromatographic separation and its effi- ciency. It is here where the specialist practitioner may be in his element and the infrequent user somewhat over-awed. Consideration is given at some length to chromatographic theory with mathematical and mechanistic dependencies being covered in some detail-somewhat excessive for those only requiring a working knowledge of the technical aspects. Despite this, most chapters do return to extensive application data and the whole book is extremely well referenced allowing the reader ample opportunity to explore particular aspects in further specialist sources of the scientific literature.An excellent chapter by Bob Hodges and co-writer on the reversed phase chromatography of synthetic peptides should provide the novice and experienced chromatographer alike with much information of value in ‘guestimating’ the likely behaviour of a given amino acid sequence when subjected to chromatography and how best to approach its chromato- graphic optimization. Dedicated chapters also give consideration to the purifica- tion of membrane proteins, viral proteins and monoclonal antibodies in addition to the analytical determination of physiological amino acids, HPLC of synthetic oligonucle- otides and DNA fragments also merit dedicated chapters, although such application is not the primary focus of the book, as does the separation of peptides and proteins by high- performance capillary electrophoresis.All in all, this is a well-written and well-presented book that comprehensively covers the many aspects, both theoretical and practical, affecting HPLC. It should prove of value to the dedicated chromafographer and occasional enthusiast (or enthusiastic occasional!) alike and is worthy of serious consideration for addition to personal bookshelves and specialist libraries. Paul W. Sheppard Element-Specific Chromatographic Detection by Atomic Emission Spectroscopy Edited by Peter C. Uden. ACS Symposium Series 479. Pp. x + 350. American Chemical Society. 1992. Price US $74.95. ISBN 0-841 2-21 74-X. This book is nicely bound and presented, and is said to have been ‘developed from’ a symposium sponsored by the Analytical Division of the ACS.Because of the quality of the presentation, I was surprised to encounter on page 257 a suddenly different typeface showing that it was actually photo- produced from the authors original typescripts. This is usually used as a method of producing proceedings quickly, which in a field changing as rapidly as this one would be a valid use of the technique, except that it has still taken two years. It is presumably an indication of the spread of laser printers that T had to read to page 257 to find a courier typeface! Personally, I would have preferred to see a little less on in-house constructed equipment and more on the performance attain-78N ANALYST, JUNE 1993, VOL. 118 able with commercially available instrumentation, but this is probably inevitable at this stage of development of these hyphenated techniques.I cannot believe that most industrial laboratories can have access to the engineering facilities needed to build their own detectors. Having said all this, there is still a great deal of interest in this book. There is an excellent overall review of atomic emission chromatographic detection systems by Uden from Massachusetts, a corresponding one on plasma mass spec- trometric detection systems and a number of papers on different plasma and optical set-ups. The practical analytical papers were most to my taste, with the observations of the team from the 3M Corporate Research Laboratories after 12 years industrial experience being very informative.I found the results presented by Hooker and DeZwaan from Upjohn fascinating, using commercially derived equipment to produce a combined AES-MS detector to examine residues and metabolites in complex biological matrices. Two papers on speciation were indicative of the elegant work that can be done using these methods. Childress and co-workers showed results on the speciation of selenium by HPLC-DCP and Gerth and Keliher married ICP to an ion chromatograph to obtain species specific detection of both Fe"/Fe"' and CrVCr"'. Overall, it is an interesting book, but one probably more attractive to workers still engaged in developments in this field rather than to the practising analyst who is looking for solutions to his specific analytical problems.I would strongly recommend it to one of these latter, however, who is seriously considering the acquisition of a commercial version of this equipment-he or she will learn a great deal. R. C. Rooney Data Fitting in the Chemical Sciences By Peter Gans. Pp. xii + 258. Wiley. 1992. Price f29.95. ISBN 0-471-93412-7. Unlike many texts in this area, the first chapter of this book begins with a simple example that is understandable to a wide variety of readers, namely 'do coins lose mass after being in circulation for several years?' Each year there is a distribution of masses of coins, but fitting the data to coins up to 18 years old shows that a very slight decrease in the mean mass (as determined by curve fitting) is not significant. The key link between statistics and curve fitting is established.The body of the text is aimed very much at readers who want a mathematical insight into methods for curve fitting, rather than at applications scientists. The second chapter introduces the theory of errors. Chapter 3 covers linear least squares including methods such as singular value decomposition. It is oriented towards understanding of algorithms and is very valuable for potential programmers. The subject of Chapter 4 is non-linear least squares. These methods are not of much interest to analytical chemometrics, and refer to situations where exact physical models such as sinewaves, Lorentzians and exponentials are expected (e.g., in kinetics or spectro- scopy). The simplex method is introduced as a method for minimizing the error of a double exponential equation.In fact, simplex methods are often naively used in analytical chemistry where there is insufficient knowledge of the influence of factors on an experimental response but are very effectively used in computational algorithms. Selection of models is discussed in Chapter 5 , but mainly in terms of spectroscopy, where there may be very precise constraints on the system (e.g., if an NMR peak is a triplet we may assume that the widths of all three components are equal, that the ratios are 1 : 2 : 1 and that the peaks are Lorentzian in shape). Chapter 6 will be more of interest to the analytical chemist and concludes with an example of determination of Al at trace levels by atomic spectroscopy. Issues such as whether the data are sufficiently good for a straight line calibration model, whether the blank is truly zero, and what the confidence is in the prediction are all addressed.Polynomials are discussed in the next chapter. This is mainly concerned with fitting local polynomials for smoothing, differentiation and integration. Savitzsky-Golay filters will be familiar to analytical chemists, but there is a large family of related approaches that are well summarized and present good reading. Chapter 8 involves fitting functions, and reflects the strong cultural divide between analytical and physical chemists. Multiple exponentials, Gaussians and Lorentzians are fre- quently of interest in physical chemistry. Confidence in these models (e.g., if a kinetics experiment is assumed to involve two competing reactions each with an exponential profile) is an important area.Analytical chemists rarely come across these types of problems, although the first section (spline functions) is of more general interest. Chapter 9 is a fairly mathematical introduction to Fourier transforms and includes a discussion of the convolution theorem, smoothing in the time domain, and Fourier pairs. Chapter 10 illustrates some of the techniques discussed earlier in the context of potentiometry (multiple equilibria). Finally, there are several mathematical appendices and a reading list. This book is definitely written by a physical chemist and demonstrates that there is still a major gulf between physical chemistry and analytical chemistry. Statistics, matrix algebra, curve fitting and the like are common to both areas, but, surprisingly, there is very limited interdisciplinary co-opera- tion.The word 'chemometrics' should not just apply to applications within analytical chemistry but throughout che- mistry as a whole. Analytical chemists can learn a lot from communicating with physical chemists and vice versu. I recommend this book as good reading for the mathematically minded analytical chemist willing to broaden hidher horizons. The cross-fertilization of ideas is crucial to the advancement of all disciplines. There has been very strong resistance within the analytical community to recognizing that workers in closely related disciplines are equally able to contribute to the development of chemometrics. Hopefully this text will help bridge this gulf.Richard G. Brereton Applications of Enzyme Biotechnology Edited by Jeffrey W. Kelly and Thomas 0. Baldwin. Pp. viii + 310. Plenum Press. 1992. Price US$85.00. ISBN 0-306- 44095-4. In the Foreword to this book the authors described the papers therein as a smorgasbord of topics of importance to the biotechnology industry. This is an excellent description of the breadth of content of the book; six main topic areas are covered. These are Diagnostic Therapeutic Applications of Radiolabeled Antibodies, Selective Functionalization of Alkanes by Enzymes and Their Models, Protein Folding and Refolding, Environmental Biotechnology, New Techniques in Protein Processing and Expression Systems for Exogenous Proteins. With such a diverse range of topics, there must be a danger, that detailed coverage of any one topic is lost in the breadth.To some extent the book does suffer from this problem, with a maximum of only four papers in each topic area, but generally the quality of the papers compensates for the quantity. I particularly enjoyed the papers on the Diagnostic Therapeutic Applications of Radiolabeled Antibodies. These three papers were taken together and were described as a mini-symposium.79N ANALYST, JUNE 1993, VOL. 118 Many readers will be familiar with the earlier IUCCP Symposia; this book represents the proceedings of the ninth Symposia run by the Industry-University Cooperative Che- mistry Programme. The Symposium was held March 18-21, 1991, at Texas A & M University and was the second in a two- part series focusing on biotechnology.Bearing in mind the all encompassing nature of the title of the Symposium, i.e., Applications of Enzyme Biotechnology , the authors of the papers and the editors have coped well in drawing together such a wide range of topics from a diverse and broad field in a comprehensible form. I do feel, however, that the title of the book should have indicated that it represented the proceed- ings of the IUCCP Symposium to aid the reader in positioning its content. The book will be of interest and value to those working both in industry and in academia in the growing field of biotechnology. B. G. Henshaw W-NMR of Natural Products. Volume 1. Monoterpenes and Sesquiterpenes By Atta-ur-Rahman and Viqar Udin Ahmad. Pp. x + 968. Plenum. 1992. Price US $135.00. ISBN 0-306-43897-6. This volume is the first in a series devoted to the 13C-NMR data of natural products. It covers a selection of monoter- penes, sesquiterpenes and their glycoside derivatives reported up to late 1989. The compounds are arranged by structural type and, within each structural type, by increasing relative molecular mass, then by carbon number and finally alphabetically. Trivial names only are used; where these were not given by the original authors, the compounds are named from the first letters of the genus and species from which they were isolated. Neither systematic names nor Chemical Abstracts Registry numbers are given; the latter in particular seems an unhappy omission in these days of on-line database searching. There are no fewer than five indices (compound name, molecular formula, relative molecular mass, biological source and compound type). The layout of the book is generous, even profligate in the case of the monoterpenes, where just two structures, with chemical shift data, occupy a page size only slightly smaller than A4. Structures are clearly drawn, but closely-related compounds are sometimes shown in different orientations (e.g. , menthol and isopulegol). Where checked, chemical shift data have been accurately transcribed from the original references. The book includes about 1600 compounds, of which around 80 are halogenated materials of marine origin. It is difficult to discern what were the criteria for inclusion, however. Menthol is present; menthone is absent. Geraniol is found, but not nerol. Amongst the sesquiterpenoids, cedrol, 6-cadinene and b-elemene are absent. Despite these limitations, the volume should be a useful source of data to workers involved with these compound classes. P. C. Bevan

ISSN:0003-2654    

DOI:10.1039/AN993180075N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

79N ANALYST, JUNE 1993, VOL. 118 Future Issues will lnclude- Ferrocene-mediated Thermal Biosensor-Bin Xie, Masoud Khayyami, Titus NWOSU, Per-Olof Larsson, Bengt Danielsson Use of Chemometric Factor Analysis For Chromatographic Integration: Application to Diode-array High-performance Liquid Chromatography of Mixtures of Chlorophyll a Degra- dation Products-Yi-Zeng Liang, Richard G. Brereton, Olav M. Kvalheim, Ali Rahmani Experimental Method to Correct Fluorescence Intensities for the Inner Filter Effect-Nanda K. Subbarao, Robert C. MacDonald Method for Group Determination of Total N-Nitroso Com- pounds and Nitrate in Fresh Gastric Juice by Chemical Denitrosation and Thermal Energy Analysis-Peter I. Reed, Guoping Xu Rapid Partial Digestion of Biological Samples With Nitric Acid for the Determination of Trace Elements by Atomic Spectrometry-Shahida B.Niazi, David Littlejohn, David J. Halls Characterization of Acidic Dyes Using Euclidean Distance Measurements of Variables Derived From High-performance Liquid Chromatographic-Visible Multi-wavelength Data- P. C. White, T. Catterick Electrocatalytic Reduction of Hydrogen Peroxide at a Station- ary Pyrolytic Graphite Electrode Surface in the Presence of Cytochrome c Peroxidase: A Description Based on a Microelectrode Array Model for Adsorbed Enzyme Mole- cules-Alan M. Bond, Fraser A. Armstrong, Felix N. Buchi, Andrew Hamnett, Allen 0. Hill, A. Martin Lannon, Olwen C. Lettington, Cynthia G. Zoski Curve Resolution and Quantification of Pyrazines by Dif- ferential Pulse Polarography Using A Kalman Filter Approach-Mark Selby, Serge Kokot, Mark Hodgkinson, Ni Yongnian Application of Supercritical Fluid Extraction in the Phar- maceutical Industry: Supercritical Fluid Extraction of Meges- trol Acetate From a Tablet Matrix-J.R. Dean, J. Lowdon Complexation of Poly(oxyethy1ene) in Analytical Chemistry. A Review-Tetsuo Okada Highly Sensitive Detection of Non-reducing Carbohydrates in Liquid Chromatograph y-Shuji Y amauchi, C hie Nakai, Noriyuki Nimura, Toshio Kinoshita, Toshihiko Hanai Fluorescence Plastic Thin-film Sensor for Carbon Dioxide- Andrew Mills, Qing Chang Atomic Absorption Spectrometric Detection of Biotin- cymantrene as a Metallo-tracer for the Avidin-Biotin System- -Isabelle Remy, Pierre Brossier Supercritical Fluid Chromatography With Electron-capture Detection in the Determination of Agrochemicals-Keith D.Bartle, Anthony A. Clifford, Robert Moulder Supercritical Fluid Extraction and Chromatography-Mass Spectrometry of Flame Retardants From Polyurethane Foams-Graham A. MacKay, Roger M. Smith All-solid-state Instrument for Fluorescence-based Fibre-optic Chemical Sensors-Peter C. Hauser, Susie S. S. Tan Determination of Deuterium in Brines and in Hypersaline Aqueous Solutions by Mass Spectrometry Using Zinc as Reducing Agent-A. Tanweer Determination of Radon-222 and Radium-226 in Water Samples by Cerenkov Counting-R. Blackburn, M. S. Al-Masri Effect of Solvent Type on the Determination of Total Iodine in Milk Powder and Human Serum by Inductively Coupled Plasma Mass Spectrometry-Hans Vanhoe, Franqoise Van Allemeersch, Jacques Versieck, Richard DamsSON ANALYST, JUNE 1993, VOL.118 EUROANALYSIS VIII The Eighth European Conference on Analytical Chemistry will be held at the University of Edinburgh September 541,1993 Organized by the Analytical Division of The Royal Society of Chemistry on behalf of WPAC/FECS Scientific Promamme Euroanalysis VIII will cover developments in instrumentation and methodology in all areas of analytical chemistry, with em- phasis on industrial, biomedical and environmental analysis. The programme will be designed to appeal to both practising analytical chemists in industry and those in academia who are teaching and carrying out research. The programme will consist of invited keynote lectures and contributed oral and poster papers.In order to ensure high quality, all contributed papers will be refereed. Social Programme A comprehensive programme is being planned for participants and accompanying persons. It will include half- and full-day excursions, and various evening events including a whisky tasting and a Buffet Reception at the Royal Museum of Scotland. Publication All of the invited lectures will be published in a collected volume as the proceedings of the conference. Authors of con- tributed papers will be encouraged to submit manuscripts for publication in either The Analyst or the Journal of Analytical Atomic Spectrometry (JAAS). Topics Some of the topics covered are: Industrial Analysis Validation of Analytical Measurements, Process Control Analysis, Materials Analysis (including Surface Analysis), Energy Related Analysis Pharmaceutical Methods and Drug Metabll'sm, Forensic Science, Bioselective Methods, Trace Elements in Medicine Separation Science, Molecular Spectroscopy, Atomic Spectrometry, Electroanalytical Techniques, Expert Systems and Chemometrics,Coupled Techniques, Sensors, Laser-based Techniques, How Analysis Pharmaceutical and Biomedical Analysis Environmental Analysis Atmosphere, Soils/Sediments, Food/Drink,Water Instrumental Techniques Conference Secretariat: Honorary Chairman, E.J. Newman Conference Presidium: D.T. Bums, Belfast (Chairman); J.F.K. Huber, Vienna; L. Niinisto, Espoo; P.G. Zambonin, Bari Secretary and Conference Organizer: Miss P.E. Hutchinson, Analytical Division, The Royal Society of Chemistiy, Burlington House, Piccadilly, London W 1V OBN, UK Tel. 071 437 8656; Fax 071 734 1227; Telex 268001 All correspondence and requests for further information should be addressed to the Conference Organizer.

ISSN:0003-2654    

DOI:10.1039/AN993180079N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JUNE 1993, VOL. 118 583 The Opening Address to SAC '92 Laboratory of the Government Chemist, Past and Future Chemical analysis is important. Today, analytical measure- ments play an essential part in many areas of everyday life: in monitoring health; in controlling the quality of products and processes; in the enforcement of regulations; and in the protection of the environment. Analysis is frequently an essential ingredient in research and development and in innovation. It has been estimated that approximately 1000 million analytical measurements are undertaken in the UK each year. This is equivalent to over 30 every second of every day in the year. Contrast this with the situation 150 years ago. When the forerunner of the Laboratory of the Government Chemist was set up in London in 1842, chemical analysis was in its infancy.There were no Periodic Tables and no agreed atomic weights. There was no concept of valency. There was no recognizable laboratory glassware; it was little more than 10 years since the first primitive burette had been devised by Gay-Lussac. Another 11 years would elapse before titration, using recognizable pipettes and burettes, started to emerge as an established technique. The Laboratory of the Board of Excise was founded by Mr. George Phillips, who was initially the only member of staff. He was a self-educated man and a career Excise Officer who had gained experience of examining adulterated samples of tobacco at a series of seizures and trials in the north of England. It appears that in 1842 he simply offered his services to the Board of Excise and set up a small laboratory in the City of London.At this time adulteration of tobacco, prohibited under the recent robacco Act, was widespread. Phillips rapidly developed methods to detect a remarkable range of adulterants such as sugar, molasses, various leaves of colts- foot, endive, rhubarb, peat moss, chicory, starch-the list was nearly infinite. We know today that smoking is bad for our health, but smoking cocktails such as these must have been an even riskier occupation. However, the Board of Excise's interest in tobacco was not prompted by a concern over the health of the nation, but rather by a desire to maximize its revenue. The mid-19th century was the golden age of adulteration, and large sums of money were to be made by traders and lost to the exchequer as a result of fraudulent trade. The development of the Laboratory over the last 150 years has mirrored the development of society and its changing concerns.By 1859 the Inland Revenue, of which the Excise Department had become a part, decided that Phillips and his Laboratory should be established on a more permanent footing; it was made into a separate department and Phillips was given one permanent assistant. At the same time the Laboratory moved from Gresham House in the City of London to Somerset House, the new headquarters of the Inland Revenue. The work of the Laboratory had expanded to cover other adulterated substances such as soap, pepper and coffee. In 1864, Phillips was given a special payment by the Treasury of 5500 in recognition of his work; he was praised for 'the improvement he has effected in the instruments and apparatus used in the laboratories .. . and for his services generally in carrying out the new system of assessing the new duties on wine'. It appears that, in this instance, the Civil Service had already introduced performance-related pay! Work to protect Government revenue continued to be the main occupation of the Laboratory until 1875 when the Laboratory was appointed referee analyst under the new Sale of Food and Drugs Act, one of the first pieces of legislation specifically designed to protect the consumer and not the revenue. Fig. 1 1913 Apparatus for the determination of original gravity of beer, This was a significant change. Other government depart- ments, such as the Admiralty, began to send samples for quality checks.This led to the decision in 1894 to set up an official Government Laboratory under Dr. (later Sir) Edward Thorpe, an eminent chemist who also took on responsibility for a second laboratory, the Custom House Laboratory, which had been set up in 1878. In 1897 the central Laboratory moved into its first purpose-built facility in Clement's Inn Passage , adjacent to Kings College Hospital off The Strand in London. Fig. 2 Wine distilling apparatus, c . 1880 The attention to detail in the Clement's Inn Laboratory set new and high standards in laboratory design. A fascinating paper published in Nature in 1897 describes everything from the pitch-pine parqueterie flooring to the high ceilings and roof.The ice-making facilities involved use of a carbonic584 ANALYST, JUNE 1993, VOL. 118 anhydride refrigerating machine, and in summer months the temperature of ordinary water was lowered by passing it from cisterns on the roof down to the refrigeratory machine-room where it ran through a cooler fitted with coils through which cold brine circulated. The working tables were mahogany tops 1; in thick (1 in = 2.54 cm) at a height of 37 in above the floor. The specification was detailed and comprehensive. The new Laboratory undertook a wide range of work on products, foods and alcoholic beverages and, under Thorpe, it expanded to include work related to the health problems caused by the match and lead-glazing industries. In 1911 the Government Laboratory was given independent status as the Department of the Government Chemist with the Principal given the title of Government Chemist.During the period from the foundation of the Laboratory until the First World War, the first half of our history, chemical analysis developed dramatically. In 1842, George Phillips’ principal apparatus had been the optical microscope and the analyses carried out were primarily qualitative. By the end of the 19th century quantitative analysis was well established. Burettes, pipettes, polarimeters, refractometers, micro-spectroscopes-instruments designed for studying the absorption spectra of coloured solutions-spectroscopes based on spark emission, specific gravity bottles and hydr- ometers were now all in common use. Fig.3 Brass hydrometer with associated weights Using these, by present-day standards still primitive, tools, the laboratory carried out a wide range of detailed, careful and thorough analyses. However, with the exception of some fundamental work initiated by Thorpe, it was in the period after the outbreak of the First World War, under the leadership of Professor Sir James Dobbie, F.R.S., that the Laboratory’s scientific reputation grew. The creation of the Government Laboratory as a separate department brought with it a remit to recruit young chemists of higher academic attainment, and the Laboratory became involved in a much wider range of work for the Admiralty, War Office, Air Ministry, Ministry of Munitions and the War Trade Depart- ment. Research began on new analytical methods such as the study of ultraviolet absorption spectra.During the early decades of this century the Laboratory established a reputation for the development and use of physical methods in chemical analysis. The remit of the Laboratory also expanded. Sir Robert Robertson, F.R.S., who succeeded Sir James Dobbie as Government Chemist in 1921, was asked to undertake a number of investigations in areas of general interest to the public: the carriage of dangerous goods, atmospheric pollution, the possible dangers to health arising from the use of lead tetraethyl in motor spirit, etc. Despite this growth in R & D and technical support activities, the Laboratory’s primary role continued to be to carry out large numbers of repetitive and semi-routine analyses for its customers within the Government.The high spot was in 1940 when 560 354 samples were analysed. Having subsequently fallen off during the Second World War, the number of analyses nearly reached this point again in 1952, but repetitive work has declined slowly but steadily since then. After a period of deep involvement in the war effort, the first decade after the Second World War was a period of evolutionary change for the Laboratory. New methods were introduced, including X-ray diffraction and infrared spectro- photometry, and some new applications, including work on the Geological Survey, were undertaken. In 1959 the Labora- tory lost its quasi-independence and became part of the Department of Scientific and Industrial Research, and in 1964 moved to new premises south of the River Thames in Cornwall House, Waterloo, London.The LGC became increasingly involved in environmental concerns. In the early 1960s the then Government Chemist, Dr. David Lewis, warned householders of the need to wash fruit and vegetables to remove pesticides. He chaired a committee to find a method for detecting small amounts of DDT. A little later the Laboratory become involved in the debate over the fluorida- tion of water. Four major developments over the last decade stand out. Early in the 1980s, thanks to the foresight of the then Government Chemist, Dr. Ron Coleman, the Laboratory became involved in the industrial applications of biotechnol- ogy, managing a programme on behalf of the DTI (Depart- ment of Trade and Industry), by now the parent department in government for the Laboratory.It was recognized that, whereas major chemical and pharmaceutical companies might have the resources to exploit the new wave of discoveries in biological science, the government had a role in assisting the technology transfer process, particularly in relation to smaller and medium-sized companies. While LGC managed this new programme, the Laboratory also took important steps to increase the strength of its own microbiological, and subse- quently analytical molecular biological, effort. The second major event of the 1980s was a white paper, ‘Measuring up to the Competition’, which identified the need for the national measurement system to embrace chemical measurement. My immediate predecessor, Mr. Alex Wil- liams, played a major part in the thinking behind the white paper and he also played an important role in the launch of the Valid Analytical Measurement (VAM) Programme.These initiatives put the Laboratory on a European, and increasingly global, path of collaboration over the mutual acceptance of analytical measurements. The third and highly significant development during the 1980s was that the uncertainty over the future of the Laboratory, which had preoccupied the Laboratory for many years, was at last removed; the decision was made to move to Teddington. Finally, at the time of the move to our splendid purpose- built laboratories, LGC was launched as an Executive Agency within the DTI with the clear remit to earn income to cover our full costs and with a much higher degree of management autonomy than before.It is perhaps too early to judge the full effects of these changes, but, so far, LGC has been highly successful as an agency. Our Annual Reports show that we are strong financially and that we are growing steadily. With the large administrative load of the move to Teddington and the change to agency status behind us, we can now concentrate on developing for the future. While the chemical methods of the 19th century and the physical methods of this century will doubtless continue to play their exceedingly important parts, I believe that as weANALYST, JUNE 1993, VOL. 118 Fig. 4 Main laboratory, Clement’s Inn, 1934 585 approach the next century there will be radical changes in analytical science. We have already seen the beginning of a trend towards greater automation and the use of robotics.I believe productivity will improve at both ends of the analysis process. Some of the major gains will come from improved methods of extraction and sample preparation at the ‘front end’ while at the ‘back end’ of analysis the use of neural networks for pattern recognition will assist in the interpretation of complex analytical results. Secondly, the use of biological systems in analysis will become increasingly important. The LGC is currently deve- loping DNA probe techniques, which, coupled with the amplification of its immensely powerful polymerase chain reaction, will allow the sensitive detection of biological entities in a variety of challenging matrices, not amenable to conventional chemical and biological methods.These tech- niques are beginning to be used in the routine analysis of natural materials-for example, the identification of leather species, the detection of food pathogens and so on. I believe biological methods will lead to the development of what might be called ‘recognition science’, the use of sensitive biological responses to identify very specifically different analytes. Thirdly, I think we must all be aware of the move away from the laboratory. It makes sense, where possible, to use remote sensors rather than to bring samples back to the laboratory. Where this is not possible, kits are increasingly used for field tests. I am not suggesting that those of us who work in laboratories will immediately be out of a job, but I believe the first line of analysis will shift away from the laboratory.This will enable many more samples to be taken, with results that will have much greater statistical significance. Of course, more difficult problems and confirmation tests will continue to demand the full range of methods available in an advanced analytical laboratory. Fourthly, as new biological methods, sensors and kits are introduced, the problems of ensuring that measurements are valid will increase enormously. Dr. Bernard King has addressed current issues concerned with Llie mutual accep- tance of analytical results; this issue will, I believe, become vastly more important in the future. Fifthly, many analyses that are performed are carried out because of requirements of regulations, for example to demonstrate that permitted levels are not exceeded or to ensure that the composition of an article is what is on the label.In many instances, permitted levels have been set at what the analyst can deliver, but, as advances in analysis allow the detection of smaller and smaller amounts of substances, we have a duty as scientists to ensure that regulations are set on the basis of informed evaluation of risk rather than simply on what we as clever analysts can detect. Finally, I believe that even greater attention will be paid to the business aspects of analysis. Perhaps it seems a little strange at an international conference on analytical science to consider the management and financial aspects of our field; yet, certainly for LGC, these will be priority concerns over the next few years.The LGC’s roots were in trade. One-hundred and fifty years ago it was thought to be cost-effective to employ George Phillips as the revenue being lost through the adulteration of tobacco was very significant, and throughout our history we have had clear customers in government for the services that we have offered, who have been well aware of the benefits-in terms of trade and revenue, the environment, health, the enforcement of law, food quality, etc.,--of using the services of scientists. Yet, as scientists, much of the satisfaction we have got from our jobs has been in providing excellent science; we have perhaps given rather less attention to the other aspects of our interaction with customers. ‘Customer care’ is today becoming a rather hackneyed phrase, but the need to ensure that the customer obtains what he requires is as important in our business as it is for British Airways or Allied Carpets! Our customers are just as concerned about what one might call the pre- and post-processing parts of our service; the process in which we respond to a request by preparing a proposal and subsequently entering into an agreement, on the one hand, and the presentation of results or a report and the submission of an invoice, on the other.At LGC we are currently putting a great deal of effort into these aspects of our work. Some of the more obvious signs are the setting up of a small business development team, the appointment of key customer managers to ensure that we maintain good communications at all stages with our major customers, and the introduction of a new financial and management information system to track progress on all of our many contracts, from major programmes to one-off analytical tasks, and to ensure that the customer obtains the information that he requires.Another aspect of our development as an analytical business concerns staffing and organization. Like many organizations of our kind we have inherited a rather hierar- chical structure with emphasis on grades and, what are called in the Civil Service, ‘commands’. The LGC’s organization structure, which has changed little over the post-war period, has relied on relatively small, what we call subdivisions, which have specialized in a particular area and have to a large extent ‘done their own thing’.This concept of, if you like, mini- businesses, which sometimes even act in competition with one another is, I believe, inappropriate in the 1990s, a decade that promises to be one of major changes characterized by considerable uncertainty. We are moving towards a flatter, less hierarchical structure, which we believe will give us much greater flexibility in responding to changes and much greater strength in tackling new areas of work. These changes in the culture of our organization are vital,586 ANALYST, JUNE 2993, VOL. 118 not only because analytical science is changing-I have already mentioned the introduction of automation, use of test kits and so on-but also because our markets are becoming much more competitive. In the UK the present government’s policy is to put out the services that the Government requires to competitive tender wherever possible.This is causing radical changes within the departments that serve govern- ment. Moreover, the new minister responsible for science has promised a white paper next year which could herald the biggest shake-up of the organization of government science since the Science and Technology Act of 1965. Major changes are also taking place internationally. The single market, which began on January 1, 1993, means that goods are free to circulate within the European Community without being re-inspected to ensure that they comply with regulations. This means that analytical certificates from one part of the community will have to be taken on trust in another. We as analysts urgently need to respond to GATT and to the increased globalization of trade by ensuring that there is a system in place, in the way that there is in the physical measurements field, for analytical data from different parts of the world to be fully trusted. Another aspect to the business of analysis is the cost side. The high cost of equipment and facilities means that we, as laboratory managers, have to ensure that our capital invest- ments bring returns and that equipment will be fully utilized. In some, mainly routine, fields there is probably an over- capacity in the market and at LGC we will be concentrating on selected, mainly more complex, areas of laboratory and consultancy work, on which we have built our reputation. With major changes already taking place and with the prospect of further radical changes in the next few years, LGC is working hard to ensure that our organization is efficient, cost-effective and flexible, and one which can respond to changing customer requirements. We have 150 interesting, rewarding and successful years behind us. I am confident that, over the coming years, we will move from strength to strength and that, when he/she stands up in 2042 at a conference jointly organized between the Royal Society of Chemistry and LGC, my successor will be able to look back, with as much pride as I have done over 150 years, over what will then be 200 years of history. R. D. Worswick Government Chemist

ISSN:0003-2654    

DOI:10.1039/AN9931800583

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JUNE 1993, VOL. 118 587 Development of an International Chemical Measurement System" Plenary Lecture Bernard King Laboratory of the Government Chemist, Queens Road, Teddington, Middlesex, UK W7 7 OLY Systems are required to ensure that analyses carried out in different laboratories are comparable, and as the requirements become more stringent the task becomes more difficult. We already have many of the components of an international system, there are, however, gaps and there is no adequate overall framework t o facilitate collaboration. This paper reviews some of the driving forces that will shape future requirements and proposes an outline system covering both conceptual issues and the organizational infrastructure. The following underpinning concepts and requirements are discussed: clearly defined targets in the form of requirement specifications; knowledge of trueness or measurement uncertainty; provision of traceability through an unbroken chain of calibration t o primary standards; and the use of quality systems t o provide transparency.Some of the key organizations operating at the UK, European and international levels are considered in terms of their contribution t o learned and professional activities, metrology, the provision of a quality focus, accreditation and the production of standards. The main new requirements are: an international organization t o act as a focus for analytical quality and more strategic planning of collaborative work programmes. Keywords: Measurement system; quality; measurement uncertainty; european organizations; traceability In his opening address at the SAC '92 Conference, the Government Chemist, Richard Worswick, spoke about the historic developments and the forces shaping the future of analytical chemistry.In this paper it is proposed that if we are to respond to the challenges of the 21st century we will need to develop a more formal and comprehensive international chemical measurement system. Although it is not formally recognized or even well known in analytical circles, we already have national and international systems but these are more suited to physical measurements than chemical analysis. Nonetheless, we already have many of the necessary com- ponents, ranging from the SI unit, the mole, to chemical reference materials and accreditation schemes complying with international quality standards.Put simply, the system, consists of activities that help eiisure that chemical analysis is valid and that an analysis carried out in one laboratory is comparable with similar analyses carried out in other parts of the world. In recent years, there has been growing recognition that we need to do more to ensure the quality of our work and a great deal has and is being done to develop some of the components of the measurement system. What we need to do now is to fit the components together to form a coherent system that will be adequate to serve our future needs. This paper discusses recent developments and indicates where more action is required. An attempt is also made to describe an overall structure that ties the strands together.My specification for the system is that it should address both conceptual issues such as measurement traceability and the organizational infrastructure, in terms of geographical region, type of activity and sectoral interest. The system must also be based on the quality principle 'fitness for purpose' and be sufficiently flexible to cope with state-of-the-art measurements and simple routine analysis. Finally, it must place emphasis on international rather than national activities and structures. Driving Forces The driving forces to which we need to respond are increasing complexity of requirement, automation/remote sensing, * Presented at SAC '92, an International Conference on Analytical Chemistry, Reading, UK, September 20-26, 1992.demand for quality and value for money, and international- ism. Society will continue to demand more analyses and more complex analysis. Advances in technology and information technology will help us to respond to the demands by facilitating automation, on-line analysis and remote sensing. However, these developments will further increase customer expectations for instant on-the-spot analyses. These develop- ments represent opportunities and threats to the analytical chemist. One issue will be our ability to provide quality data at an acceptable price. Customers will also increasingly expect a better dialogue with the analyst to agree the requirement and visible evidence that the data and their interpretation are valid. The simultaneous pressures on quality and price will require economies of scale that will lead to greater specializa- tion and present business difficulties for some laboratories.The final driving force is internationalism. The single European market is part of a continuing trend to eliminate barriers to international trade. As our world effectively shrinks we need to harmonize our systems to ensure that analyses carried out in different countries are comparable. The control of disease and of environmental pollution are further examples of issues that are critically dependent on sound chemical analysis and international cooperation. All of these issues will have a major impact on our work and we need to reassess and, where necessary, upgrade our support systems. Historically, analytical chemistry has served society well but there are clear signs that some chemical analyses are not fit for purpose.Unless we act now the situation will become worse and could lead to loss of public confidence in our work. The Quality Problem The quality problem can be illustrated by the results of interlaboratory comparisons such as the Community Bureau of Reference (BCR) study of trace toxic elements in milk powder. The summary data in Table 1 show that the spread of results obtained by laboratories across Europe was initially very large and, incidentally, it was much greater than expected. However, when the scientists concerned collabor- ated it proved possible to identify the causes of the differences and subsequently to obtain good agreement.588 ANALYST, JUNE 1993, VOL.118 The quality problem is being increasingly recognized and much is being done to improve matters. The challenge before us is to build a system that is sophisticated enough and robust enough to serve the needs of the 21st century. Key Organizations Some of the organizations that contribute to the international chemical measurement system are listed in Table 2. These organizations cover different activities such as professional matters or accreditation and also different geographical regions ranging from national groups to European regional groups and in some cases the interest is world-wide. The European and UK organizations can be replaced by other equivalent national and regional organizations. Also, a number of other organizations could be added to the table, particularly if it were to be extended to include sectoral activities such as the environment or health.The learned and professional societies provide the bed-rock of technical support. They are showing increasing interest in quality matters, particularly in areas such as training and technology transfer. There are growing national and regional programmes, such as the Valid Analytical Measurement (VAM) programme in the UK and the BCR programme in Europe. Focus groups sych as the Chemical Measurement Advisory Committee (CHEMAC) in the UK and the European Focus for Analy- tical Chemistry (EURACHEM) in Europe are helping to coordinate activities but as yet there is no truly international organization covering all aspects of the chemical measurement system.Accreditation is reasonably well served in that we have internationally agreed quality standards and both national bodies and international coordination in place. The challenges here are to rationalize the requirements of the different schemes and to develop criteria that cover both routine and more research-based work. Standards making is Table 1 Ranges of results (ng g-’) for trace elements in milk First Second Element intercomparison intercomparison Cd 0.4-4500 1-5.6 Hg 0.6-42 0.73-1.27 Pb 68-5500 92.4-1 12.5 c u 470-9257 475-700 Table 2 Some key organizations involved in the international chemical measurement system Area of activity UIC Europe? International* professional RSC FECS IUPAC Learned and Metrology VAM BCR BIPM Quality focus CHEMAC EURACHEM ? Accreditation NAMAS WELAC ILAC Standards BSI CEN I S 0 * RSC = The Royal Society of Chemistry; VAM = Valid Analytical Measurements; CHEMAC = Chemical Measurement Advisory Committee; NAMAS = National Measurement Accreditation Ser- vice; BSI = British Standards Institution.t FECS = Federation of European Chemical Societies; BCR = Community Bureau of Reference; EURACHEM = A European Focus for Analytical Chemistry; WELAC = Western European Laboratory Cooperation; CEN = European Committee for Standard- ization. t IUPAC = International Union of Pure and Applied Chemistry; BIPM = International Bureau of Weights and Measures; ILAC = International Laboratory Accreditation Conference; I S 0 = Inter- national Organization for Standardization. again well served by organizations. What is required is a reduction in duplication and a harmonized approach that is more transparent.The geographical cooperation within specific activities, such as standards making, is generally effective but communication between the activity groups is less well developed and this is an important function for groups such as CHEMAC, EURA- CHEM and a possible new international organization. A serious limitation to the effectiveness of many of these groups is the fact that much of the work is unfunded and carried out in the margins by enthusiasts. One of the keys to progress is the provision of national and international funding and where appropriate top-down strategic planning of the work. Before expanding on some of the recent developments, the conceptual issues involved in the measurement system will be discussed, Underpinning Concepts For the measurement system to work effectively we need a clear understanding of the conceptual issues and how they fit together.Targets First we need more clearly defined targets in the form of requirement specifications, study designs and sampling proto- cols. When engineers build a bridge or construct a car, they work to detailed specifications and plans and by comparing what is produced with what was specified it is possible to assess quality. All too often the specification for chemical analysis is ‘what is this?’ or ‘how much of X is in this sample?’. Our approach is too simplistic and we must devise a protocol that helps customers specify their requirements in detailed terms appropriate to the task.For example, accuracy is an expensive commodity and too much can be almost as bad as too little. With more complex investigations, a study design is needed to evaluate the feasibility of options and prepare a work plan. The answer will often depend on the way the sample is taken and how it is processed. Sampling is often considered to be the weakest link in the quality chain and is often the major contribution to measurement uncertainty. Studies of surfaces, the examination of forensic specimens and the characteriza- tion of contaminated land, for example, present special sampling problems. At the Laboratory of the Government Chemist we have long recognized the importace of sampling and it is therefore particularly pleasing that we have recently won a contract from the UK government to help improve this part of the measurement system.Trueness For a measurement to be of value we need to know how reliable or true it is. The traditional approach has been to determine the precision by carrying out repeat measurements. Unfortunately, this approach fails to take account of some systematic errors and as a result it is common to overstate the accuracy or trueness of measurement data. An alternative approach, which is used by physicists and is beginning to gain acceptance with chemists, is the concept of measurement uncertainty.’ Uncertainty is an estimate of what the error might be and involves professional judgement. Another definition of measuremcnt uncertainty is what is unknown about the error. Some of the key sources of error in chemical analyses are listed in Table 3.The assessment and control of thcse errors requires detailed validation of each step of the process. In some cases errors can be eliminated or corrected for, but there will always be some uncertainty concerning each source of error and this con- tributes to the uncertainty of the measurement.ANALYST, JUNE 1993, VOL. 118 589 Table 3 Sources of error in chemical analysis Activity Errors Sampling Heterogeneity, decay/loss, contamination Calibration Analysis Certified value, mismatch between sample and Weighing, dissolution, ashing, digestion, dilution, standard separation, derivatization, contamination, chemical interference, measurement, data manipulation, reporting The overall uncertainty U is the root mean square of the sum of the component uncertainties ( U1-U,): u = (up + u,2 + u32 + .. . .)& where U,-U,, are estimated as standard deviations. Some errors will be of a random or pseudo-random nature and can be estimated from the standard deviation of repeat measurements. Others will be systematic in nature, F.g., incomplete extraction or peak overlap. It is sometimes possible to assess the uncertainty experimentally, for ex- ample, different extraction procedures can be used and spiking can often help assess the level of recovery; sometimes it will be necessary to rely on professional judgement. Knowledge of bias can also be obtained from the use of alternative, preferably primary, methods and the use of certified reference materials when these are available.Of course, known systematic bias can be corrected for provided that the uncertainty associated with the bias is significantly less than the bias. In practice, only two or three factors can be expected to dominate the overall uncertainty because in the root mean square equation small components make negligible contributions to the answer. The overall uncertainty should be expressed as a band describing the range within which the true value lies with a certain probability. The magnitude of acceptable uncertainty will vary with the application. If the estimated uncertainty is too large for a particular purpose, it is necessary to eliminate some of the sources. This approach is relatively new but there is now a draft International Organization for Standardization (ISO) guide1 that explains the underlying theory and indicates how uncertainties can be assessed in different fields of measurement.At the Laboratory of the Government Chemist we have a project that is attempting to assess the overall uncertainty of some typical analytical measurements. We hope to be able to publish some fully worked examples that will help others assess their measurement uncertainties. Proper attention to measurement uncertainty, in addition to providing technical benefit, will provide market differentia- tion between high- and low-grade results. Traceability Traceability exists when there is an unbroken chain of calibration linking measurements made in one laboratory with measurements made in other places. Also, there should be an unbroken chain linking measurements made at the working level to primary standards.The links in the chemical traceability chain are: SI units such as the kilogram and mole; primary standards such as the kilogram; relative atomic masses; pure chemical reference materials; primary methods; matrix reference materials; secondary methods and reference materials; and working methods and reference materials. The custodian of the SI units and certain primary standards is the International Bureau of Weights and Measures (BIPM). Although there are primary standards for physical measures such as mass, length and time, there is no primary standard for the chemical measure, the mole, and that is one of our fundamental problems. Because of the vast number of different types of chemical analyses it is not feasible, of course, to have a single chemical primary standard, but nonetheless we need to establish a link between working analysis and primary standards.This link is partly provided by the relative atomic masses, which relate the mole to the kilogram. Unfortunately, chemical factors such as matrix effects constitute a break in the traceability chain and therefore chemical standards or reference materials are also required. Chemical standards in turn must be characterized and certified by chemical analysis, thus creating a closed circle. To break out of the circle we need absolute or primary methods. Isotope dilution mass spectrometry, which relies on measuring only isotopic ratios, a unitless measure, and mass is an example of such a method.In principle this process can be continued down to the secondary standards and working levels, but in practice there are many missing links in the traceability chain. Although there are about 20000 chemical reference mater- ials available world-wide, these are still not enough to calibrate the vast range of chemical measurements. Also, there is no system for distinguishing the top level of primary reference materials from lesser secondary and working level materials. It is hoped that two recent developments will help improve matters. First, the BIPM has established a working group to examine what can be done to improve the traceability of chemical analysis. This group is examining the feasibility of establishing a small number of primary chemical reference materials and reference methods to form the top of a chemical traceability system.Although it will take some years before any tangible benefit can be achieved, it is an essential part of the process of improving the quality of chemical analysis. Another recent development is the establishment of an IS0 working group to prepare a guide for the accreditation of reference material producers. Although this will not guaran- tee the reliability of products, it will help raise standards and could be a first step towards the international certification of reference materials themselves. Transparency Transparency exists when there are systems in place that ensure the reliability of data and provide the customer and user with clear evidence of reliability. Having a formal quality assurance (QA) system and preferably accreditation goes a long way to achieving transparency.There are three main types of quality standards: (i) I S 0 Guide 25; Euronorm (EN) 45000; National Measurement Accreditation Service (NAMAS) MlO for testing and calibration laboratories; (ii) I S 0 9000; EN 29000; British Standard (BS) 5750 for manufacturing and service industries; and (iii) Good Labora- tory Practice (GLP) for non-clinical testing of chemicals for health and environmental purposes. These standards are published under a variety of numbers by both national and international standards bodies. Although there are small, but for some purposes significant, differences between the standards, the underlying principles and require- ments are broadly the same. The standards are interpreted in different ways, however, by the accreditation bodies who place different emphasis on different aspects of the require- ments. For example, in the UK NAMAS prefer to accredit laboratories for specific tests and their system does not yet fit comfortably with non-routine analysis or research and devel- opment (R & D) work.In GLP, particular emphasis is placed on study design, record keeping and the role of the Study Director. On the other hand, BS 5750 takes a broader approach to quality but applies to all activities within the laboratory. Organizations are required to define their quality objectives and then to install and monitor systems that ensure they are achieved. In the UK, over 300 laboratories are NAMAS accredited for some aspect of chemical analysis and many other countries590 ANALYST, JUNE 1993, VOL.118 are progressing in a similar way in response to customer demand. There are two major problems to address, however. First, the multiplicity of standards and approaches need to be harmonized into a single system that covers all aspects of chemical analysis and that is internationally recognized. Second, we need to find ways of persuading the majority of laboratories who have no formal QA to improve their practices. A significant step towards the harmonization of accredita- tion standards is the preparation of a detailed technical guide describing best practice. This document is at an advanced draft stage and has been prepared by a joint working group of the Western European Laboratory Cooperation (WELAC) and EURACHEM.Although prepared specifically for the EN 45000 standard, the guide is equally applicable to other systems. Transparency is also provided by participation in profi- ciency testing schemes in the form of routine interlaboratory comparison exercises. A growing number of schemes are now available and some operate on an international basis. The burden of QA on laboratories is considerable and we must ensure that a cost-effective balance is achieved. It is important that proficiency testing is kept to a minimum and that it is effectively organized. An IS0 protocol that describes good practice in the organization of proficiency testing schemes is in the course of preparation and this will help to ensure that schemes comply with best practice. The following section returns to organizational matters and explains some of the developments that have occurred in recent years, starting with the UK. Developments in the UK In 1989, a government White Paper was published entitled ‘Measuring up to the Competition.’ It set out the govern- ment’s policy and plans for measurement support and announced a new programme to help improve the validity of analytical measurement.The first VAM programme ran for 3 years and in 1991 it was extended for a further 3 years. The Laboratory of the Government Chemist is the main contractor but a number of other organizations are also involved. There are 11 projects and the work is of three types: promotion and technology transfer; development of the organizational infra- structure; and technical projects concerned with topics such as trace analysis.The largest project is ‘Calibration and Tracea- bility,’ which covers work on reference materials and the development of primary methods for their certification. Other technical projects such as trace analysis, sampling and statistics range from R & D concerned with solving measure- ment-related problems to the development of protocols that describe good practice. The work is always aimed at providing analytical chemists with the basic tools needed to ensure valid measurement. The government spending on the VAM pro- gramme represents the core of a larger activity supported by other institutes and industry. A great deal of emphasis is being placed on promotion and technology transfer.These activities have two aims. The first is to raise awareness of the importance of valid analytical measurement, particularly with the customers of measure- ments. Only when the customers recognize the importance of quality will we be able to make real progress. The second aim is to communicate new developments and good practices that already exist in particular sectors to the broader analytical community. The second major thrust of the VAM programme is to develop the organizational infrastructure both in the UK and internationally; CHEMAC has been established to provide a UK focus for analytical quality and to provide a mechanism for input to international affair$. Senior level representatives from government, industry, academe and professional organ- izations such as The Royal Socie1,T of Chemistry ensure effective cooperation between the many interested groups and oversee the activities of working groups on reference mater- ials, proficiency testing, and education and training.European Scene There is a great deal of new European activity largely stimulated by the drive to complete the single European market. Of the many organizations there are two that are central to the harmonization of analytical measurement practice. The BCR organizes and helps fund projects needed to solve community-wide measurement problems. Much of the work is concerned with the organization of collaborative projects that lead to the certification of reference materials. A recent evaluation of the BCR programme by a group led by Dr.T. Quinn, the Director of BTPM, concluded that much good work has been done but the resources were insufficient to tackle the task. It is recommended that future programmes are much larger and that a strategic plan be developed to ensure that maximum benefit is obtained. The BCR is central to improving measurement quality in Europe and many of us look forward to it playing a larger role. EURACHEM There is also a need for a broadly based focus for analytical quality matters in Europe and this is provided by EURA- CHEM. Since EURACHEM was established in 1989 in Frankfurt, it now has members from 18 countries. The aims are to provide a framework for cooperation between chemical laboratories across Europe and to promote good analytical quality practices.Membership is open to European Community and Euro- pean Free Trade Association countries and observer status can be afforded to other countries in Europe and to European- based organizations such as BCR and the Federation of European Chemical Societies. The main work of the organiza- tion will increasingly be done by specialist working groups such as the Education and Training Working Group. Some of the activities undertaken by EURACHEM during the last two years are organization of collaborative projects, preparation of guide for the accreditation of chemical laboratories, organization of workshops for specialists from across Europe on education and training in analytical QA and traceability of chemical measurements, preparation of a protocol on profi- ciency testing, and organization of symposium on Good Automated Laboratory Practice.One of the roles of EURACHEM is to provide liaison between horizontal activities such as metrology, accreditation and standards making. To complete the network, member countries are encour- aged to establish national EURACHEM groups to provide 2- way dialogue between European-level activities and the broader community of working analysts. The aims are to identify priority issues by consultation at the working level, to identify partners for collaborative projects and to keep analytical chemists informed about developments. International Organizations Analytical chemistry is well served by international organiza- tions except that there is no single organization to act as a focus for all the various standards that go to make up analytical quality.An international meeting, in Atlanta, GA, USA, ir March 1993 was planned in order to establish ways of improving collaboration between the many organizations and countries that are active in the field. It was expected that either a new organization would be formed or an existing organiza- tion would expand to provide a focus.ANALYST, JUNE 1993, VOL. 118 59 1 Sectors The final aspect of the infrastructure matrix is the sectoral one. There are some activities such as high-level metrology or the operation of accreditation schemes that are generic in that they serve all or a number of sectors. Other activities are of relevance to specific sectors such as the pharmaceutical industry or forensic science. This aspect of the infrastructure can be viewed either as a sphere with generic activities at the core or as a metrology pyramid with generic activities at the apex. Either way, it is important to see all the activities as part of an over-all system so that sectors learn from each other and duplication of effort is minimized. Conclusion This paper has examined a number of areas of activity and indicated how they fit into an over-all measurement system. To summarize, we need: ( i ) greater clarity about underpinning concepts; (ii) an international organization to act as a focus for analytical quality; (iii) more strategic planning and some coordination of work programmes; and ( i v ) governments and industry to be prepared to pay for quality. There is a good deal of activity and analytical chemists are working hard to respond to the needs of society. The author is confident that with the help of our customers we can rise to the challenge of the 21st century. Reference 1 Guide to the Expression of Uncertainty In Measurement, IS01 TAG 4lWG3, International Organization for Standardization, Geneva, June 1992. Paper 2105557K Received October 19, 1992

ISSN:0003-2654    

DOI:10.1039/AN9931800587

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JUNE 1993, VOL. 118 593 Flow-through (6io)Chemical Sensors* Plenary Lecture Miguel Valcarcel and Maria Dolores Luque de Castro Department of Analytical Chemistry, Faculty of Sciences, University of Cordoba, E- 14004 Cordoba, Spain The basic features and most salient examples of flow-through chemical and biochemical sensors based on the integration of derivative analytical reactions, separation processes (dialysis, gas diffusion, sorption, liquid-liquid extraction) and detection (optical, electroanalytical, mass, thermal) are presented and discussed, and critically compared with those of probe-type sensors and conventional continuous-flow configurations, where such processes take place sequentially in separate modules. Keywords: flow-through sensor; chemical and biochemical sensors; continuous flow Devices providing direct, immediate analytical information on a given system under study are still a future goal, the accomplishment of which relies heavily on automation and miniaturization.' The main trends in the science and tech- nology of the late 20th century, in response to the basic objectives of today's and tomorrow's analytical chemistry, are the acquisition of more chemical information of higher quality by expending less material, time, effort and economic resources .2,3 What is a sensor? Defining this word is far from easy.Because sensors are the magic keys to many doors, their name is often used improperly. Ideally, a (bio)chemical sensor is an analytical device that responds in a direct, reversible, contin- uous, rapid and accurate (precise) manner to changes in the concentration of chemical or biochemical species in an untreated sample (Fig.1). It may consist of a sensing microzone where a chemical or biochemical reaction (and, occasionally, a separation process) takes place, which is connected or integrated with an optical, electrical, thermal or mass transducer. In short, the principal use of an ideal sensor is for integrating two of the three general steps of the analytical process (preliminary operations and measurement and transduction of the analytical signal). In principle, sampling, addition of reagents, detection, separation tech- niques, etc., need not be included. However, many of the sensors developed in the last few years fail to meet one or more of the defining criteria. Interestingly, many books on this topic provide no description of sensors or begin with a stringent definition, yet they subsequently deal with devices that do not operate in a direct, reversible, rapid, continuous or accurate fashion. This is also so with many papers that include the word sensor in their title, yet are concerned with devices that only meet a few if any of the basic requirements for the ideal (bio)chemical sensor, even in the absence of a sensing microzone containing an immobilized (bio)chemical species.The large number and variety of sensors reported so far make it necessary to establish classifications according to a host of different criteria: the monitored parameter (chemical or biochemical) , their nature (reversible, irreversible, dispos- able or reusable), their external shape (planar, probes or flow cells), the relationship between the sensitive microzone and the transducer (connected or integrated), the operational mode (batch or continuous), the occurrence or not of a (bio)chemical process (whether active or passive), the inclu- sion or not of an additional separation process, the type of transducer (optical, electrical, thermal, mass or otherwise), and the number of monitored species (single parameter or multi-parameter; individual or integrated).A detailed de- * Presented at SAC '92, an International Conference on Analytical Chemistry, Reading, UK. September 20-26, 1992. scription of each classification is beyond the scope of this paper. In any event, such classifications provide a good idea of how varied sensors are and show how difficult it is to establish general rules and describe their behaviour in broad terms.However, defining the generic properties of a (bio)chemical sensor is easy. Some of them coincide with basic analytical features (accuracy, precision, sensitivity and selectivity), whereas others are related to appropriate performance (reversibility , reusability for irreversible, regenerable systems and suitability for a single use for irreversible, non-regener- able systems). Time-related features such as (near) real-time response, rapidity in the reversible and regeneration processes involved and stability (long shelf and operational lifetimes) are crucial. One other set of features are related to reliability, viz., simplicity of construction and operation, ruggedness, low cost, usability with complex samples, suitability for evolving systems (portable manifolds) and the need for no interpreta- tion by the operator.Some of these features are indispensable, others only desirable. This paper reviews the state-of-the-art and trends of (bio)chemical sensors based on the integration of detection and reaction (and/or separation) in a flow cell that can be integrated with or connected to an optical, electroanalytical, thermal or mass detector for direct determination of one or more (bio)chemical analyte(s) in gas or liquid samples. Far from being exhaustive, it summarizes the fundamental prin- ciples and most significant alternatives of this type of sensor, with special emphasis on optical systems.Critical comparisons with matching probe-type and continuous-flow [flow injection (FI)] configurations are also made throughout. Generic Features of Flow-through (Bio)Chemical Sensors In conventional continuous-flow analytical systems,4.5 separa- tions involving mass transfer between two phases, (bio)chem- ical reactions and continuous detection in a conventional flow Reliable Analytical instrument Sensor '-' '-' Complex sample 1 -A---- I- Accurate (precise) I Real-time I - - - - - - - I t I - Dirkt- -I I '1 Reversible ' Basic features -,,,,I Fig. 1 Features of the ideal sensor594 ANALYST, JUNE 1993, VOL. 118 cell take place in different modules that are isolated in space, i.e., in a sequential manner [Fig. 2(a)]. There are four generic ways of integrating these steps [Fig.2(b)], namely, by combining: (1) continuous separation(s) and analytical reac- tion(s); (2) (bio)chemical reaction(s) and detection; (3) continuous separation(s) and detection; and (4) all three types of process. A device that performs detection almost simul- taneously with reaction (type 2) and separation (type 4 or 3) in the flow cell can be considered to be a sensor as it meets the main requirements described above. There are three basic types of flow-through (bio)chemical sensors (Fig. 3) according to the location of the sensitive microzone where the bio(chemica1) reaction and/or separation take place and its the relationship to the detector. Two of them [(a) and ( b ) ] rely on the use of probes connected to the instrument; the scnsitive microzone can be attached to the end of the probe (a) or incorporated into the flow cell (b).The third type of sensor involves a conventional instrument in which the sensitive microzone is incorporated into a special flow cell ( c ) . They differ from ‘probe sensors’ because in the latter the probe, either containing (active) or not containing (passive) the sensing (bio)chemical microzone, is plunged into the gas or liquid sample rather than being introduced (by aspiration or injection) into the flow cell. There is a tendency to use the word probe instead of sensor in describing disposable (single-use) sensors;6 in any event, the borderline between the two is blurred. For this reason, we prefer to use the word probe to denote rod-shaped sensors that are connected to transducers.The sensitive microzone is a single flow cell, with no reactive element in the so-called passive sensors, which makes it difficult to distinguish between a flow-through sensor and a conventional continuous-flow configuration (e.g. , an FI mani- fold). In active flow-through (bio)chemical sensors, a reactive microzone is included in the flow cell. The physico-chemical interaction between such a microzone and the components of the gas or liquid streams flowing through the system can be in the form of a simple (bio)chemical reaction, a separation process or a combination of both. As a rule, these processes are based on the immobilization of one of the ingredients of a (bio)chemical reaction, whether this be the analyte, reagent, catalyst or reaction product.7 Immobilization must be per- manent if the active component (reagent or catalyst) is to be used for a large number of determinations.If the reagent is consumed in the process, the flow-through sensor can only be used a limited number of times. On the other hand, when the analyte or its reaction product is to be immobilized, their residence in the flow cell will be temporary, so the sensor must be regenerated (i. e., the temporarily immobilized species must be removed) after each determination. Integrated separation can be accomplished by means of a membrane (dialysis and gas-diffusion processes) or a solid support in the form of a film, a porous solid or particles (sorption).X.9 The integrated (bio)chemical reaction can take place on the support (when the analyte or reagent is the immobilized (a) Conventional Detector (b) Integrated Detector Fig.2 figurations ( a ) Conventional and (b) Separations (BioIChemical 00 reactions Detection 0 integrated continuous-flow con- species), in the solution held in the cell (when the catalyst is supported on the solid) or in a reaction coil (when the reaction product is the temporarily immobilized species). Flow-through sensors are available in a variety of shapes suited to the type of detection required, their relationship (connected or integrated) to the (bio)chemical microzone and the inclusion or not of a simultaneous or sequential separation process. The most frequently used configurations are depicted in Fig. 4. In the optical flow-through cell, the light beam can reach and leave the cell directly or through optical fibres for absorption (Al) and (A2), fluorescence (Al), reflectance (A3) or (bio)chemiluminescence measurements (A4).The use of a potentiometric or voltammetric electrode in an active flow cell allows the implementation of a variety of flow-through sensors (B). Most mass and thermal flow-through (bio)sensors rely on differential measurements; they use two identical cells (one of them containing the sensitive microzone) that are arranged either in series (C) or in parallel (D). A gas-diffusion or dialysis membrane can be incorporated into the active flow- through cell by passing one (El) and (E3) or two streams (E2) through it. One of the most salient features of flow-through sensors is their compatibility with unsegmented-flow configurations,4~5 which allows the main advantages of continuous-flow mani- folds [automation, flexibility, ease of sample conditioning and calibration, development of previous (bio)chemical reactions, etc.] to be extended to this type of sensors, thereby also allowing for use on real samples. These configurations, therefore, make excellent links between real samples and flow-through sensors.The large variety of configurations of this type is described and classified according to the immobi- lized species elsewhere.7 Probably, one of their greatest assets is their suitability for performing the regeneration step in irreversible, reusable sensors in a very simple, automatic fashion compared with probe-type sensors [Fig. 5 (A)]. The three principal regeneration modes of flow-through (bio)- chemical sensors are shown in Fig. 5 (B).The first made, the simplest (Bl) , involves injecting rather a large sample volume Instrument - Sample I I rSMZ Sample -4 I Sample I Instrument ‘1‘ Fig. 3 Generic types of flow-through (bio)chemical sensors. Sensitive (bio)chemicai microzone (for details, see text) SMZ:ANALYST, JUNE 1993, VOL. 118 "1 S l ( E l ) lS * /K- SMZ I I I C I Fig. 4 Examples of flow-through cell sensors in which a sensing (bio)chemical microzone (SMZ) (type A, B, C and D) and a membrane (M) (type E) arc integratcd with an optical (type A, E l and E2). electroanalytical (type B and E3), mass (type D) and thermal (type D) detector. S, samples; RP, reflection plate; PMT, photomultiplier tubc; E, potentiometric or voltammetric electrode; PC, piezoelectric crystal; T, thermistor; FO, fibre optic; and AS, accepting stream (0.2-2 ml) into a carrier containing the (bio)chemical reac- tants for regeneration via an injection valve; as soon as the tailing end of the sample plug reaches the sensor, the regeneration process starts.The second mode (B2) involves sequential aspiration of the sample and regeneration streams via a switching valve. Finally, the third mode (B3) is based on injection of the sample volume into a (conditioning) carrier and aspiration or injection of the regenerating solution. In all instances, the signal increases as the sample plug passes through the sensor. When the tailing end of the sample plug reaches the sensor (first type), the selecting valve is switched (second-type) or the regeneration solution is introduced (third type) and the baseline, which is established by passing the regenerating (types 1 and 2) or conditioning carriers (type 3) through the system, is restored.Thus, the temporary signal obtained can be a peak (type 1 and 2) or plateau (type 3). Analytical information can be drawn from the peak or plateau height or the slope of the rising portion of the signal (kinetic method). Various examples of flow-through (bio)chemical sensors are described below, classified according to the processes that take place in the flow-through cell. All of them must meet the following basic requirements for appropriate performance: (i) the system should be reversible (or easily regenerable if irreversible); (ii) the kinetics of the processes involved (chemical and biochemical reactions, separation process, etc.) should be fast unless the catalyst is the immobilized species; (iii) the immobilization linkage should be very stable when the reagent or catalyst is to be immobilized in the flow cell; and ( i v ) the sensitive (bio)chemical microzone and the detection system should be fully compatible.Integration of Reaction and Detection Flow-through (bio)chemical sensors based on the integration of reaction and detection in a suitable flow cell rely on the permanent immobilization of one or several reagents and/or the catalyst on an appropriate support. The difference between conventional continuous-flow configurations, in which a mini-reactor is placed before the detector flow cell (occasionally called sensor systems, as in ref.lo), and true sensors is illustrated in Fig. 6. This type of sensor involves no separation process unless the immobilized reagent is partly consumed in each determination. They differ from those in which the immobilized reagent retains the analyte temporarily and a detectable change (colour, fluorescence) occurs simul- taneously. A single immobilized reagent located in a flow-through cell can be used for the determination of a variety of species by different detection principles. Surface-modified electrodes inserted into flowing systems are representative examples. 11 One such system is the carbon electrode modified with immobilized FeVFelII sites that respond amperometrically to various nitrogen oxides.12 Many of these flow-through sensors are based on immobilized, non-regenerable ( e . g . , luminol13) or regenerable [e.g., tris-(2,2'-bypiridyl)ruthenium(1i)] com- plexes14 that act as chemiluminescence reagents, as well as on fluorophores15 and phosphors. 16 Frei and co-workers used a flow-through cell containing two reagents, viz., a solid [bis(2,4,5-trichlorophenyl) oxalate (TCPO)] and a fluoro- phore (3-aminofluoranthene), immobilized on different types of supports for the determination of hydrogen peroxide,17 glucosels and anilines. Ic) By immobilizing pyrenebutyric acid596 ANALYST, JUNE 1993, VOL. 118 B ,&, S I RC I S 1 Flow-th roug h sensor / C I Fig. 5 Regeneration modes in the use of irreversible-reusable or probe-typc sensors (A) and flow-through sensors (B).S, samples; RD, regenerating dissolution; C, carrier; RC, regenerating carrier; IV, injection valve; and SV, switching valve in a silicone membrane or on a glass support placed in a flow- through cell, molecular oxygen can be determined in gases by its quenching effect on the native fluorescence of the reagent .20 The same principle was used by immobilizing benzo[ghi]pyrene in a silicone-rubber membrane that was placed on a planar glass plate, separation of excitation light and fluorescence emission being accomplished by total inter- nal reflection.21 A flow-through cell containing a palladium wire as sensing element attached to a monomode optical fibre was used to determine hydrogen in gases by formation of palladium hydrides, which resulted in longitudinal strain of the optical fibre that was transduced to a phase retardance in a light beam guided by the fibre and detected by inter- ferometry.22 Catalysts (enzymes) immobilized in flow-through cells can be used to develop biosensors based on various detection principles that can be coupled on-line to continuous-flow configurations. The main alternatives in this context are: (i) passing the sample-reaction plug through the sensitive micro- zone once (conventional) or several times (iterative reversal of the flow direction and open-closed configurations); and (ii) stopping the flow as the plug reaches the sensor. The choice is dictated by the rate of the (bio)chemical reaction. Chemi(bio)luminescence reactions are generally fast enough for implementation in straightforward continuous- flow configurations with a catalyst immobilized in the flow cell.Thus, haemin, haemoglobin and horseradish peroxidase were used to determine hydrogen peroxide by the luminol reac- tion,23 co-immobilized bacterial luciferase and oxidoreductase were employed to determine nicotinamide adenine dinucleo- tide (reduced form) (NADH), nicotinamide adenine dinu- cleotide phosphate (reduced form) (NADPH), flavin mono- nucleotide (FMN) and FMNH2 (FMN, reduced form),24 and firefly luciferase was utilized to determine adenosine triphos- phate (ATP), creatine phosphate and phosphokinase.25 A set- up consisting of a flow-through cell housing an enzyme-coated optical fibre and a combined optical-enthalpimetric detector was reported by Dessy et aZ.26 The ability of FI configurations to implement stopped-flow methodologies can be exploited to improve sensitivity and selectivity (reaction-rate measure- ments) by means of (bio)chemical sensors [Fig.7(a)]. In this way, ethanol in real samples can be determined spectrophoto- metrically using alcohol dehydrogenase immobilized on the R and/or C (a) s D ( b ) , R and/or C Fig. 6 Difference between (a) a sensor system and ( h ) sensor in which the reagent (R) and/or the catalyst (C) is immobilized on a suitable support and placed in a reactor or a flow-through cell that is integrated with the detector (D). rcspectively. S, sample flow-cell walls.27 Optical glucose sensors based on glucose oxidase immobilized on a germanium crystal28 and an As-Se- Te fibre29 accommodated in a flow-through cell and combined with Fourier-transform infrared-attenuated total reflection detection were recently reported. Measurements were made under stopped-flow conditions.Multi-peak recordings can be obtained by passing the sample plug through the (bio)chemical sensor containing the immobilized catalyst several times. This can be accomplished by iteratively reversing the flow direction [Fig. 7(b)]3" or by using an open-closed configuration31 [Fig. 7(c)]. Thus, by using immobilized P-D-glucuronidase in a photometric flow cell, the hydrolysis of 4-nitrophenol-~-glucoronide was moni- tored with five devices: three of them were true biosensors (an enzyme was immobilized in the flow cell) that differed in the way that reaction rates were measured (by the stopped-flow mode or with iterative passage of the sample plug)32 (see Fig.7), whereas the other two were biosensor systems [Fig. 6(a)] relying on the iterative, sequential passage of the sample plug through the enzyme reactor and the flow cell.33 The use of parallel dual biosensors (see Fig. 4, E) for implementing calorimetric measurements makes an interest- ing alternative to immobilized enzymes integrated in trans- ducing elements (two thermistors) .34-38 They have been used to determine a variety of substrates. Integration in flow-through cells of an enzyme (glucose oxidase39.4" or lactate oxidase41) and an indicator reagent whose fluorescence is dynamically quenched by molecular oxygen has facilitated the development of a new series of biosensors. Inverted video imaging microscopes have been used to develop receptor-based flow-through biosensors using cray- fish antennae, the nerves of which are connected to a physiological amplifier via ground and reference wire poten- tiometric electrodes.One such sensor was successfully applied to the determination of pyrazinamide in water.42 Integration of Separation and Detection This type of (bio)chemical sensor involves reversible mass transfer between two phases (solid-liquid, liquid-liquid or gas-liquid) in a flow cell that is integrated with or connected to the detector.8 The species involved in this process can be analyte(s) (when their physico-chemical features are directly usable for detection) or previously formed reaction products.They differ from the other types of sensor in that no (bio)chemical reaction takes place in the flow-through cell (see Fig. 8). There are several examples of flow-through sensors that rely on a separation process through a membrane without (bio)chemical reaction; such is the case with an integrated gas-diffusion-atomic absorption cell for the deter- mination of mercury,43 a variety of film-coated voltammetric and potentiometric electrodes used in continuous-flow systems that allow matrix effects to be minimized11 and a gas- diffusion membrane coating an iridium-metal oxide thermal detector.44ANALYST, JUNE 1993, VOL. 118 597 stop Time - 4 Change - D t w II C U A Time - Time ---t Fig. 7 Alternatives to reaction-rate measurements by use of immobilized enzymes ( C ) in the flow-through cell of a photometric detector (D).(a) By stopping the flow; ( h ) by iterative reversal of the flow direction; and ( c ) by using an open-closed configuration. SV, Selecting valve; W, waste; and P, pump The most frequently employed flow-through sensors of this type are based on the use of sorbent material (e.g., ion- exchange beads, C18 bonded phase silica beads) that is packed in the flow cell of a non-destructive detector (e.g., a photometer or fluorimeter), where the analytes or their reaction products are temporarily immobilized. These are irreversible, reusable sensors inasmuch as two steps (retention and elution as implemented in the configurations depicted in Fig. 5 ) take place sequentially but simultaneously with detection in each determination.If the analyte(s) can be directly and temporarily retained by the support, they must lend themselves to continuous detection. Such is true for the direct spectrophotometric determination of ionic copper based on its native colour; the ions are temporarily retained in a flow cell packed with a cation-exchange resin and elution is effected by injecting a nitric acid solution.45 Flow-through sensors based on the temporary immobiliza- tion, on a solid support, of reaction products formed previously in the continuous manifold offer a wide range of applications. For example, bismuth can be determined by forming iodide complexes and retaining them in a flow- through cell containing Sephadex anion exchanger as sup- port.46 In addition, the temporary retention of the product formed between CrVI and diphenylcarbazide on a cation- exchange resin was exploited for the determination of this ion.47 Cyanide was determined at the ng ml-I level using a Fig.8 Flow-through sensors based on the integration of a reversible separation process, through a membrane (M) or on the surface of a solid support (SP), and detection. S , sample containing the analyte; RP, reaction product; and DZ, detection zone merging-zones FI manifold into which two plugs of sample and reagent (pyridoxal-5-phosphate) were simultaneously in- jected; fluorimetric flow-through cell packed with an anion exchanger allowed retention and detection of the reaction product to be integrated.48 Phosphate was determined by forming an ion associate between molybdophosphate and Malachite Green that was temporarily retained on Sephadex LH-20 packed in a photometric flow-through cell.49 The classical Molybdenum Blue reaction with ascorbic acid has also been used in this context .SO Ammonia can be determined at the pg ml-l level by temporarily immobilizing its product (Berthelot reaction) on Sephadex QAE packed in a photo- metric flow ce11.51 A fluorimetric flow-through sensor for the determination of very low concentrations of fluoride based on the temporary immobilization of the ternary complex zirco- nium(1v)-Calcium Blue-fluoride showed improved analytical features compared with its matching probe-type sensor.52 Aluminium can be determined using a room-temperature phosphorescence chemical sensor based on the formation in a coil of a complex between aluminium and 8-hydroxy-7-iodo- quinoline-5-sulfonic acid (ferron) , which is temporarily immo- bilized on an anion-exchange resin packed in a flow ce11.53 The determination of p-aminobenzoic acid was accomplished by using a customized flow cell accommodating a paper filter in a straightforward FI configuration through which a silver hydrosol was circulated; detection was effected by surface- enhanced Raman spectrometry.54 A film of Prussian Blue coating a quartz crystal microbalance was used as a flow- through mass sensor to determine dissolved electroinactive ions .55 One of the most promising aspects of this type of sensor is the ability to take advantage of photometric diode-array detectors to monitor simultaneously absorbances on a support (with or without an immobilized species) at various wave- lengths.The joint use of this principle and classical deconvolu- tion chemometric approaches allows the development of multi-parameter sensors. Mixtures of amines can be deter- mined on the basis of their intrinsic absorbances by injecting a large sample volume into a methanol-water carrier in order to drive the plug to a flow cell packed with CIS bonded phase silica beads for temporary retention.56 A determination of carbamate pesticide mixtures at the ng ml-l level based on the temporary retention of their reaction products on CI8 bonded phase silica beads placed in the flow cell of a diode-array spectrophotometer was recently reported.57 The same flow- through sensor was successfully used as a post-column system in high-performance liquid chromatography (HPLC) .58359 Other spectroscopic approaches can be used to develop multi-parameter flow-through (bio)chemical sensors.An example is the simultaneous determination of the different forms of vitamin B6 (i. e., pyridoxal, pyridoxal-5-phosphate and pyridoxic acid) based on the formation of fluorescent complexes with Be" in ammonia solution and their temporary retention on CIS bonded phase silica beds packed in a conventional flow cell. Discrimination relied on derivative synchronous fluorescence measurements .60598 ANALYST, JUNE 1993, VOL. 118 Integration of Reaction, Separation and Detection With flow-through (bio)chemical sensors based on triply integrated continuous systems, separation processes and reactions take place either sequentially or simultaneously.On the other hand, detection occurs simultaneously with one or the two other processes (Fig. 9). This type of sensor involves permanent immobilization of the reagent and/or the catalyst. Occasionally, however, no active ingredient of the (bio)chem- ical reaction is immobilized, i.e., the reaction takes place in the solution held in the flow cell. Separation processes can be enacted through membranes (dialysis, gas diffusion) or solid supports packed with beads or coated with a film. The immobilized reagent can play a single- or two-fold role: acting as ingredient of the derivatizing reaction and/or faciliting the separation processes. Ionophores immobilized in a flow-through cell can tempor- arily retain ionic species from the flowing sample solution.The derivatizing reagent can be either dissolved or immobilized [Fig. 9(a)]. Werner el al. 61 developed various fluorimetric flow-through sensors based on the temporary retention of cationic analytes (K+, NH4+) on controlled-pore glass beads, where different ionophores (dibenzo-18-crown-6, valinomy- cin, nonacin) were non-covalently immobilized; a dissolved fluorescence probe (8-anilinonaphthalene- 1-sulfonic acid) previously mixed with the sample yielded a fluorescent ion pair on the solid surface. A calcium ion selective flow-through optrode based on the fluorescence quenching of a dye (the C- 18 ester of Rhodamine B) incorporated into a lipid membrane containing a calcium ion selective ionophore was recently reported.62 A flow-through photometric sensor with a plasti- cized poly(viny1 chloride) (PVC) membrane containing an NH4+-selective macrotetrolide ionophore, an H+-selective neutral chromatographic and a lipophilic anion was success- fully used for the determination of ammonium ions.63 Also, a PVC membrane placed in a fluorimetric flow-through cell containing Hexadecylacridine Orange and valinomycin was employed for the determination of potassium .64 Permanent retention of a colorimetric or fluorimetric pH indicator dye in a flow cell was first accomplished by Kirkbright et al.in 1984.65 Temporary retention of H+, OH- or other species is the operational principle of this type of sensor [Fig. 9 (C)]. Sulfide ions can be determined by using various reagents immobilized on porous organic polymers and fibre optics.66 Commercially available indicator papers placed in a flow cell provided a reflecting plate that was used in conjunction with two optical fibres for pH measurements by reflectance spectroscopy.67 They were applied to the determi- nation of rainwater pH68 and the sequential determination of acids and b a ~ e s .6 ~ If an immobilized enzyme is incorporated into cellulose acid-base pads, the resulting sensor can be used for the determination of urea70 and penicillin.71 The use of reagents immobilized on solid supports (either as films or beads) that are in turn placed in a flow cell allows temporary retention (separation) and derivatization to take place simultaneously [Fig. 9(c)]. This approach has been applied to the spectrophotometric and spectrofluorimetric determination of metal ions and other chemical species. Thus, copper was determined at the ng ml-l level by immobilizing 4- (2-pyridy1azo)resorcinol on a cation-exchange resin packed in a spectrophotometric flow cell; the system was made reusable by including an eluting ligand (2-mercaptoacetic acid) in the carrier.72 By using a similar arrangement, beryllium was determined spectrofluorimetrically with morin immobilized on an anion-exchange resin .73 Chlortetracycline immobilized on an anion-exchange membrane placed in a flow cell to which a branched optical fibre was attached was used for the spectrofluorimetric determination of calcium by formation of a chelate.74 Aluminium was determined in dialysis fluids and concentrates with a flow-through spectroiluorimetric fibre- optic sensor containing the 8-hydroxyquinoline derivative Kelex-100 immobilized on Amberlite XAD-7.75 Also, low Fig.9 Generic types of (bio)chcmical flow-through sensors based on the triple integration of separation, reaction and detection. Differ- ences lie in whether the integrated rocesses take place sequentially [ ( a ) and (b)] or simultaneously (cf S, sample; and K, additional reagent (for details, see text) concentrations of iron in waters and wines were determined by means of a spectrophotometric flow-through sensor contain- ing an anion-exchange resin in the thiocyanate form.76 A flow- through spectrophotometric flow cell accommodating a PVC membrane on to which a lipophilized chromogenic ligand, 3 - octadecyloxy-4-(2-pyridylazo)resorcinol, was immobilized was successfully used to determine zinc.77 An optical wave- guide coated with a copper-organophosphine complex placed in a flow-through cell was employed as a reversible chemical sensor for sulfur dioxide.78 Water and ethanol can be determined in a spectrophotometric flow-through sensor based on the immobilization of lipophilic trifluoroaceto- phenone derivatives on a PVC membrane that extract the analytes to form hydrates and hemiacetals, respectively, and change their absorption spectra.79 These triply integrated (bio)chemical sensors have been demonstrated to be suitable for implementing immunoassays based on the immobilization of one of the components of the biochemical interaction.Thus, antibodies [anti-mouse immu- noglobulin G (IgG)] covalently immobilized on to a rigid beaded support placed in a bioluminescence flow-through cell was used for the determination of antigens (mouse TgG); a two-site immunoassay was accomplished by consecutive injection of the sample, acridinium ester-labelled antibodies and alkaline hydrogen peroxide to initiate luminescence.80 An immunomembrane containing the antigen bovine IgG mounted in a bioluminescence sandwich flow cell was used in an FI system for the determination of mouse anti-bovine IgG; four sequential injections (analyte, goat anti-mouse IgG- horseradish peroxidase conjugate, buffer and substrates plus luminol reagents) into an assay carrier containing bovine serum albumin and p-iodophenol were required.81 A capaci-ANALYST, JUNE 1993, VOL.118 599 tance flow-through cell using antibody or antigen immobilized on a tantalium oxide surface for implementing real-time immunoassays was recently reported.** Sensors based on integration of dialysis, reaction and detection rely on the use of a membrane located in a flow cell to deliver one of the ingredients of the (bio)chemical reaction directly. Determination of metal ions was accomplished using a pressurized membrane through which a spectrofluorimetric reagent was forced into the flow ce11.83 Sucrose was deter- mined after conversion into glucose (using an enzyme reactor containing invertase and mutarotase) and development of the classical luminol chemiluminescence reaction of glucose oxidase, which was delivered directly through a membrane accommodated in the chemiluminescence flow ce11.84 Perm- selective film-coated enzyme electrodes are another example of this type of triply integrated sensor.” There are several examples of integrated gas-diffusion- chemical reaction-detection (bio)chemical systems in the literature.Most of them are ammonia chemical sensors. In these, the analyte or its reaction product is the species involved in the separation process. A universal sandwich membrane flow-through cell integrated with absorption, reflectance or chemiluminescence detection for determination of ammonia and hypochlorite was reported recently .X5 Ammonia can also be determined using a gas-diffusion membrane placed in a flow cell and fibre-optic reflectance measurements; detection is based on an acid-base indicator that can be either immobilized67 or not.86 A flow cell shaped like that in Fig.4 (Fl), was developed for the determination of ammonia,s7 the sensitive microzone consisting of a PVC optrode membrane containing the same ingredients as used in ref. 63. A flow-through gas chemiluminescence sensor for the determination of molecular oxygen based on the diffusion of the analyte through a membrane and its subsequent reaction with 1,1’,3,3’-tetraethyl-A-bis(imidazolidine) dissolved in hexane was reported by Freeman and Seitz.88 Conclusion A critical comparison between flow-through (bio)chemical sensors based on integrated separation, reaction and detection with their matching probe-type sensors and conventional continuous-flow configurations (in which all three steps take place sequentially in separate modules) allows the advantages and disadvantages of using the former in analytical chemistry to be clearly established.7.8 The most outstanding advantages of integrating flow- through (bio)chemical sensors are: (i) the increased sensitiv- ity89 resulting from miniaturization, which reduces dispersion of the inserted sample and concentration of the analyte or its reaction product, a typical feature of integrated separation techniques; (ii) the selectivity being indirectly enhanced by the removal of interfering species and the avoidance of parasitic signals by use of kinetic approaches based on differential rather than absolute measurements; (iii) the implementation of the regeneration step, which can be carried out readily, quickly and conveniently, is dramatically facilitated; and (iv) the use of FI configurations to implement (bio)chemical sensors offers interesting, practical assets such as high versatility and sample throughput, ready calibration, reduced sample and reagent consumption and easy adaptation to on- line process monitoring.On the other hand, the most serious drawbacks of this type of flow-through sensors are: (i) the lack of compatibility between the sensitive microzone (support, membrane, etc.) and the detection system required to ensure appropriate performance of the analytical method concerned; (ii) prob- lems arising from the kinetics of the separation and reaction steps involved; (iii) difficulties in remote sensing and micro- zone monitoring; and ( i ~ ) the scarcity of appropriate chemical and biochemical systems meeting the essential requirements for integration in a flow-through cell.We believe that it would be interesting to start a new age in the development of (bio)chemical sensors by systematically applying them to real analytical problems ( e . g . , environmen- tal, food, pharmaceutical and industrial samples) to exploit the myriad of academic developments achieved so far. 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ISSN:0003-2654    

DOI:10.1039/AN9931800593

出版商:RSC    

年代:1993

数据来源: RSC