摘要:

'""An a I y stThe Analytical Journal of The Royal Society of ChemistryAnalytical Editorial BoardChairman: A. G. Fogg (Loughborough, UK)M. Cooke (Sheffield, UK)H. M. Frey (Reading, UK)J. M. Gordon (Cambridge, UK)G. M. Greenway (Hull, UK)S. J. Hill (Plymouth, UK)D. L. Miles (Keyworth, UK)J. N. Miller (Loughborough, UK)R. M. Miller (Gouda, The Netherlands)B. L. Sharp (Loughborough, UK)M. R. Smyth (Dublin, Ireland)Y. Thomassen (Oslo, Norway)P. Vadgama (Manchester, UK)J. F. Alder (Manchester, UK)A. M. Bond (Victoria, Australia)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. Heineman (Cincinnati, OH, US,A.Hulanicki (Warsaw, Poland)I. Karube (Yokohama, Japan)E. J. Newman (Poole, UK)J. Pawliszyn (Waterloo, Canada)T. B. Pierce (Harwell, UK)Advisory BoardE. Pungor (Budapest, Hungary)J. RfiiiEka (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)4)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 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,Professor 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.Street, Toronto, Ontario, CANADA M5S 1Al.Universidad de Cordoba, 14005 C6rdoba. 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 +I 413 545 4846Assistant EditorsSarah Williams Yasmin KhanEditorial Secretary: Claire HarrisAdvertisements: Advertisement Department, The Royal Society of Chemistry, BurlingtonHouse, Piccadilly, London, UK WIV OBN.Telephone +44(0)71-287 3091. Telex No. 268001.Fax +44(0)71-494 1134.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,physical, biochemical, clinical, pharma-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 publication 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 ex-amined by at least one referee.Full critical reviews, which must be acritical evaluation of the existing state ofknowledge on a particular facet of analyticalchemistry.Every paper (except Communications) willbe submitted to at least two referees, bywhose advice the Editorial Board of TheAnalystwill 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 UK andN. America, a Group of Regional AdvisoryEditors exists. Requests for help or advice onmatters related to the preparation of papersand their submission for publication in TheAnalystcan be sent to the nearest member ofthe Group. Currently serving RegionalAdvisory Editors are listed in each issue ofThe 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 andproofs, should be directed either to theEditor, or Associate Editor, The Analyst.Members of the Analytical Editorial Board(who may be contacted directly or via theEditorial Office) would welcome comments,suggestions and advice on general policymatters concerning The Analyst.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 CB44WF.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 1 HN. Turpin Distribution Services Ltd., is wholly owned by the Royal Society of Chemistry. 1994Annual subscriptionrate EC f340.00, USA $641.00, Canada f384.00 (excl. GST), Rest of World f366.00. Purchased with Analytical Abstracts EC €718.00, USA$1351 .OO, Canada f811 .OO (excl. GST), Rest of World f772.00. Purchased with Analytical Abstracts plus Analytical Proceedings EC f851 .OO, USA$1601 .OO, Canada f961.00 (excl. GST), Rest of World f915.00. Purchased with Analytical Proceedings EC f432.00, USA $812.00, Canada f487.00(excl. GST), Rest of World f432.00. Airfreight and mailing in the USA by Publications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003.USA Postmaster: Send address changes to: The Analyst, Publications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003. Second classpostage paid at 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, 1994. 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/AN99419FX027

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

ANALAO 1 19( 7) 1429-1 640, 89N-98N (1 994) JULY 1994REVIEW'"AnalystThe analytical journal of The Royal Society of ChemistryCONTENTS1429 Derivatization by Ethylation With Sodium Tetraethylborate for the Speciation of Metals and Organometallicsin Environmental Samples. A Review-Spyridon Rapsomanikis1441 Direct and Rapid Determination of Potassium in Standard Solid Glasses by Excimer Laser Ablation PlasmaAtomic Emission Spectrometry-Yong Ill Lee, Joseph Sneddon1445 Synthesis and Efficiency of a Polyacrylacylisothiourea Chelating Fibre for the Preconcentration andSeparation of Trace Amounts of Gold, Palladium and Ruthenium from Solution Samples-Xijun Chang,Zhixing Su, Guangyao Zhan, Xingyin Luo, Wenyun Gao1451 Solid-Liquid Extraction for the Determination of Impurities in High-purity Lead by Atomic AbsorptionSpectrometry With Electrothermal Atomization-Masataka Hiraide, Yasushi Mikuni, Hiroshi Kawaguchi1455 Preconcentration of Trace Amounts of Silver and Cadmium by Ion Exchange and Micro-extraction FromWater for Flame Atomic Absorption Spectrometry-Shiquan Tao, Yoshio Shijo, Lin Wu, Lin Lin1459 Trace Metal Atomic Absorption Spectrometric Analysis Utilizing Sorbent Extraction on Polymeric-basedSupports and Renewable Reagents-Herbert L.Lancaster, Graham D. Marshall, Encarnacion R. Gonzalo,Jaromir RhiiCka, Gary D. ChristianMatrix Solid-phase Dispersion as a Multiresidue Extraction Technique for b-Agonists in Bovine LiverTissue-Damien Boyd, Michael O'Keeffe, Malcolm R . SmythDetermination of the Oil Content of Rapeseed by Supercritical Fluid Extraction-David F.G. Walker, KeithD. Bartle, Anthony A. CliffordDesign and Characterization of a Thermochemical High-performance Liquid Chromatography FlamePhotometric Detector Interface for the Speciation of Sulfur-J. Bernard, T. Nicodemo, N. N. Barthakur,J. S. BlaisInvestigation of the Stability of Medicinal Additives in Animal Feedingstuffs to Prepare ReferenceFeeds-lndu Patel, Keith R. B. Marshall, Carole Williams, Hannah Othman, Neil T. CrosbyPhysico-chemical Properties of Oxybutynin-Etsuko Miyamoto, Susumu Kawashima, Yoshifumi Murata,Yutaka Yamada, Yoko Demizu, Hitoshi Kontani, Takeshi SakaiDetermination of Ethyl N-Phenyl Carbamate, 4,4'-Methylenebis(ethy1 phenylcarbamate) and4,4'-Methylenebis(pheny1 isocyanate) by High-performance Liquid Chromatography-Eugene Milchert,Waldemar PazdziochDetermination of Dietary Fibre as Non-starch Polysaccharides with Gas-Liquid Chromatographic,High-performance Liquid Chromatographic or Spectrophotometric Measurement of ConstituentSugars-Hans N.Englyst, Michael E. Quigley, Geoffrey J. Hudson151 1 Determination of the Uronic Acid Constituents of Non-starch Polysaccharides by High-performance LiquidChromatography With Pulsed Amperometric Detection-Michael E. Quigley, Hans N. Englyst151 9 Trace Enrichment of Chlorinated Phenols From Drinking Water on Chemically Bonded Sorbents forHigh-performance Liquid Chromatography-Jitka Frebortova, Vera TatarkoviCova1525 Extraction and High-performance Liquid Chromatographic Method for the Determination of Microcystins inRaw and Treated Waters-Linda A.Lawton, Christine Edwards, Geoffrey A. Codd1531 Graphical Diagnosis of lnterlaboratory Quality Control Data for Surface Water Samples-James E. Gaskin1537 Spectrophotometric Determination of Mixtures of Iron(iii) and Manganese(i1) by Complexation With3-lndolylacetohydroxamic Acid and Principal Component Regression Multivariate Calibration-MercedesJimenez Arrabal, Pablo Valiente Gonzalez, Concepcion Caro Gamez, Antonio Sanchez Misiego, ArsenioMuiioz de la PeAa1541 Comparison of Multivariate Calibration Techniques for the Quantification of Model Process Streams UsingDiode-array Spectrophotometry-Kevin N. Andrew, Paul J. Worsfold1547 Use of the Latin Square Design to Study the Influence of the Experimental Parameters on ErucamideDifferential Scanning Calorimetric Curves-G.Frutos, I, Quijada, J. M. Barrales1553 Determination of Trace Amounts of Cobalt by Flow Injection With Spectrophotometric Detection-KrystynaPyrzynska, Zofia Janiszewska, Joanna Szpunar-kobinska, Merek Trojanowicz1467147114751483148914931497Continued on h i d e Back Cover-Typeset and printed by Black Bear Press Limited,Cambridge, England0003-265~C199L17: 1->INEWS AND VIEWS1557 Kinetic-Spectrophotometric Determination of Diquat Based on a Charge-transfer Complex WithCysteine-Tomas Perez-Ruiz, Carmen Martinez-Lozano, Virginia Tornas, Rocio Casajus1561156715711575157915851593159916031607161316191625162916331637Spectrofluorimetry at Zero Angle: Determination of Salicylic Acid in an Acetylsalicylic Acid PharmaceuticalFormulation-Antonino Villari, Norbert0 Micali, Massimo Fresta, Giovanni PuglisiDifferential-pulse Polarographic Determination of Zinc and Manganese in Various Pharmaceutical andBiological Samples After Adsorption of Their Morpholine-4-carbodithioates on MicrocrystallineNaphthalene-Rajesh Kumar Dubey, Bal Krishan PuriDifferential-pulse Polarographic Determination of Iron in Acids, Waters, Fruit Juices and Wines-M.E.Vazquez Diaz, J. C. Jimenez Sanchez, M. Callejon Mochon, A. Guiraum PerezDetermination of Ceftriaxone in Aqueous Humour and Serum Samples by Differential-pulse AdsorptiveStripping Voltammetry-Sacide Altinoz, Durisehvar Ozer, Aytekin Temizer, NurSen YukselDetermination of Thyroxine in Urine by Cathodic Stripping Square-wave Voltammetry-L.Hernandez, PHernhndez, 0. NietoOptimization of the Experimental Parameters in the Determination of Copper(i1) by Differential-pulse AnodicStripping Voltammetry and Evaluation of the Characteristic Detection Curves-Ana Herrero, M. Cruz Ortiz,M. Julia Arcos, Jesljs L6pez-PalaciosFast Determination of Aluminium Reactive to 1,2-Dihydroxyanthraquinone-3-sulfonic Acid in Sea-water-J. J. Hernandez-Brito, M. D. Gelado-Caballero, J. Perez-Pefia, J. A. Herrera-MelianPreconcentration and Determination of Lead Ions at a Chitosan-modified Glassy Carbon Electrode-Xu Jinrui, Liu BinAnodic Stripping Voltammetry With a Triton X-100 Modified Mercury Film Electrode Using FlowInjection-Ruelito R.Dalangin, Hari GunasinghamFlow Injection Amperometric Determination of Thiocyanate and Selenocyanate at a Cobalt PhthalocyanineModified Carbon Paste Electrode-Efstathios G. Cookeas, Constantinos E. EfstathiouApplication of a Picrolonate lon-selective Electrode to the Assay of Calcium and Piperazine inPharmaceuticals and Serum-Panayiotis G. Veltsistas, Mamas I. Prodromidis, Miltiades I. KarayannisElectrode Function of Selective Membranes for Anions of Phthalic Acid Isomers-Ryszard DumkiewiczFlow-through Photometric Sensor for Determination of Sulfonamides-M. T. Tena, M. D. Luque de Castro,M. ValcarcelDetermination of Nickel and Copper Using vic-Dioximes and Potentiometric Titration-Selahattin Serin,Yagar Gok, Serdar Karabocek, Nurbay GultekinApplication of Ethylenediaminetetraacetic Acid as a Titrant at High Degrees of Neutralization-Maura V.Rossi, Eduardo F. A. Neves, Maria E. V. Suarez-lhaCUMULATIVE AUTHOR INDEX89N Book Reviews91 N Conference Diary96N Courses97N Papers in Future IssuesCover picture: Laser ablation of zirconium metal in argon. Photograph supplied by courtesy of Doctor MichaelThompson, Birkbeck College, Department of Chemistry, University of London

ISSN:0003-2654    

DOI:10.1039/AN99419BX029

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, July 1994, Vol. 119 89N Book Reviews Capillary Electrophoresis: Principles and Practice By Reinhard Kuhn and Sabrina Hoffstetter-Kuhn. Pp. x + 376. Springer-Verlag. 1993. Price DM98.00. ISBN 3-540- 56434-9. ISBN 0-387-56434-9. This book focuses on the basic aspects of capillary electro- phoresis (CE) and is designed to be a practical guide for newcomers to the field as well as those with some experience. Consistent with the title, readers will find many helpful hints in the practice of CE as well as an excellent review of the theoretical principles behind the many different facets of CE. The book is well organized into 8 chapters which consist of 107 figures, 58 tables and 501 references (listed together in the back). Additionally there is a preface, a 4-page table of contents, a 5-page subject index, and a 10-page appendix (Chapter 8) which includes a summary of buffer systems, derivatization procedures, a glossary of symbols, a manufact- urers’ directory, and a recommended reading list. Chapter 1 briefly discusses safety considerations as well as giving a historical synopsis into the development of CE.Chapter 2 describes the basic principles governing CE and the various modes of separation, in particular isotachophoresis and isoelectric focusing; electrophoretic migration and elec- troosmosis are also discussed here. Factors that influence performance in CE are well detailed in chapter 3. Chapter 4 focuses on the instrumental aspects of CE with good discussions on the modes of injection and the various means of detection employed.Also included is a tabulated list of commercial instrumentation and comparison of their impor- tant characteristics. Chapter 5 combines a relatively thorough discussion of capillary coatings (including experimental proce- dures) with the principles of capillary gel electrophoresis (CGE) , micellar electrokinetic chromatography (MEKC), We judge this book to be particularly well suited for the CE novice’. capillary isotachophoresis (CITP) , capillary isoelectric focus- ing (CIEF), electrochromatography (EC) , capillary affinity electrophoresis (CAE), and coupled techniques like liquid chromatography-capillary electrophoresis (LC-CE), CE- mass spectrometry (CE-MS), and CITP-CE. Chapter 6 briefly examines qualitative and quantitative analysis in CE, whereas Chapter 7 is a selective review of applications.The 350 applications provided are grouped into 10 categories according to the type of analyte, and are largely presented in a tabular format with references, experimental conditions, and pertinent remarks. Finally, Chapter 8 is the appendix dis- cussed earlier. We judge this book to be particularly well suited for the CE novice. Throughout the text, helpful hints are provided to aid the analyst. One shortcoming, however, is the brevity of the discussion of qualitative and quantitative analysis (Chapter 6). These topics are an important part of any CE method, and the 8 pages devoted to them are somewhat lacking in depth and lucidity. In future editions a discussion of the optimization of integration parameters, especially ways to reduce the baseline noise associated with absorbance detection, would be benefi- cial.A survey of detector response characteristics and typical detection limits for the more common detectors would also be helpful. From the terminology employed by the authors, it is clear that they assume the reader to have prior knowledge of other separation techniques like HPLC and GC. It would be nice if the authors had included a brief comparison of these techniques with CE. Finally, as this book was designed to appeal to the beginner CE enthusiast, the authors may wish to consider including, for future editions, a few experiments that illustrate basic principles. These minor criticisms aside, this book does a good job of introducing CE to the novice. It is well written, with easy access to the references at the end of the text, and includes large numbers of informative tables.This text compares favourably with the increasing number of books available on CE, providing a concise treatment of the principles while covering a broad range of topics. Eric S. Ahuja and Joe P . Foley Department of Chemistry Villanova University, PA, USA Environmental Analysis. Techniques, Applications and Quality Assurance Edited by D. Barcelo. Techniques and Instrumentation in Analytical Chemistry. Volume 13. Pp. xii + 646. Elsevier. 1993. Price DF1465.00. ISBN 0-444-89648-1. The stated intention of this book is to serve both as a general reference for post-graduate students and as a practical reference for environmental chemists who need to use analytical techniques for environmental studies, and analytical chemists needing information on the complexity of environ- mental sample matrices and interferences.The contents are presented as four sections viz., field sampling techniques and sample preparation, application areas, quality assurance and reference materials, and emerg- ing techniques. It could, however, be argued that several of the techniques dealt with in the final section [ e . g . , use of liquid chromatography-mass spectrometry (LC-MS) for the analysis of polar pesticides; characterization of surfactants using desorption ionization-mass spectrometric methods] are now well established, rather than emerging. Of the three chapters forming the first section, one is concerned with sampling techniques for air pollutants, while the other two deal with organics in environmental waters, sediment and biota samples.These latter two chapters contain comprehensive critical reviews of the various techniques available and provide a good source of information for anyone looking for an up-date on currently favoured techniques. The only criticism of this section is that its title is a little misleading as field sampling techniques are only dealt with in the chapter on air pollutants. The second section contains six chapters on a variety of applications. The first deals with polychlorinated biphenyls (PCBs) and some metabolites and provides an excellent summary of this field, and the second chapter on official methods of analysis (mainly US EPA and EC) of priority pesticides gives useful information on pesticides and their transformation products.The third chapter on coupled- column liquid chromatography for the determination of polar pesticides demonstrates what can be achieved in this area with a little ingenuity but may be confusing for the uninitiated due to the liberal use of acronyms, some of which could be misleading. For example, in this chapter SRM is used with reference to single residue methods whereas in a latter chapter SRM refers to standard reference materials (the commonly accepted usage). There are other examples of ‘non-standard’ acronyms, and one feels that some editorial attention would have been beneficial in this respect. The remaining chapters in90N Analyst, July 1994, Vol. 11 9 this section, relating to the liquid chromatographic determina- tion of phenols and derivatives in water samples, high- performance liquid chromatographic methods for mycotoxins and phycotoxins and the determination of radionuclides in environmental samples provide good reviews of these areas. The third section, containing three chapters relating to quality assurance and reference materials, should be required reading for most organic analysts involved in environmental analysis as this area has tended to be neglected in the past.As noted earlier, the choice of the subject areas dealt with in the final section on emerging techniques is questionable as several would by now be considered to be fully-fledged. However all five chapters (relating to the analysis of polycyclic aromatic hydrocarbons (PAH) and PAH metabolites, surfac- tants, polar pesticides by LC-MS, organometallic compounds, and the potential of capillary electrophoresis) are well written and of relevance to modern environmental analysis.Generally this volume provides a useful source of up-to- date information with references through to 1992 included for most chapters, and although some inorganic chemists may feel that the contents are biased towards organics analysis, this probably merely reflects current trends in environmental chemistry. As is to be expected in a multi-authored compila- tion of this type, some parts are more readable than others, but overall this book can be recommended to its target audience, i. e . , postgraduate students, environmental chemists needing information on analytical techniques, and analytical chemists wishing to learn more about environmental che- mistry.H . A . James Principal Scientist WRc Medmenham, UK Modern Aspects of Electrochemistry. Volume 23. Edited by 6. E. Conway, J. O'M. Bockris and Ralph E. White. Pp. v + 420. Plenum. 1992. Price US$SS.OO. ISBN 0- 306-441 64-0. Volume 23 of the Modern Aspects series presents up to date reviews in two aspects of fundamental physical electro- chemistry and three chapters dedicated to applications. The review by Lipkowski deals with charge transfer reactions across monolayers attached to metal electrodes. This is an area of great activity, not only for the intrinsic fundamental interest of electron transfers through films, but also for the very important recent advances in the self- assembly of well-defined organic layers on metals.This chapter brings a well-balanced discussion of the relationship between adsorption of organic compounds and its effect on charge transfer rate constants. Marcus theory and its exten- sion to resonant transitions are presented and compared with experimental results. Lipkowski manages to convey the excitement of this active area of research and its importance to many branches of modern chemistry. Although this review is aimed at a specific area, it is written in sufficiently general terms and covers a wide background of modern electroche- mistry to be of interest to a broad audience. The second review on physical electrochemistry, by Allon- gue, is on the physical chemistry of semiconductors covered by metallic clusters.This is an important area of research for two reasons: firstly the chemistry of metallic clusters has recently received a great deal of attention, with the development of new preparation and analysis techniques. Examples of impor- tant modern applications are in the production of nano- materials. Secondly, metals attached to semiconductor sur- faces are known to decrease corrosion rates and improve the efficiency of photoelectrochemical (PEC) solar cells. The review by Allongue brings a brief general description of the fundamental aspects of the semiconductor-liquid junction and an up-to-date discussion on the influence of metallic deposits and metal ion adsorption on the photoelectrochemistry of GaAs, 11-VI materials, InP and Si.This is a very rich area of research and this review clearly shows the importance of surface derivatization of semiconductors by metals for con- trolling PEC performance. 'brings together up-to-date reviews in important areas of modem electrochemistry and will be of use not only to readers specializing in the topics covered, but to people working in physi- cal electrochemistry and electrochemical engineering'. West and Newman bring a comprehensive review of the solution of the Laplace equation for the determination of the current distribution in electrochemical systems. Various aspects of the solution methods, such as numerical approaches, coordinate transformation, conformal mapping, separation of variables, similarity transformations, boundary integral techniques and perturbation methods are presented. The authors make the important point that in spite of the increased availability of powerful computers at low cost, it is important to be able to use analytical solution methods. The practical design problems of cathodic protection are discussed extensively by Dr. K. Nigancioglu. Design paramet- ers and applications to the offshore oil industry are presented. Parkhutik, Albella and Martinez-Duart review electrical breakdown phenomena in anodic ovide films. Physical models describing filamentary breakdown, electronic process at the oxide/electrolyte interface and in the bulk oxide are discussed. This book is a valuable addition to the successful Modern Aspects series. It brings together up-to-date reviews in important areas of modern electrochemistry and will be of use not only to readers specializing in the topics covered, but to people working in physical electrochemistry and electrochem- ical engineering. D. J . Schiffrin Department of Chemistry University of Liverpool, UK

ISSN:0003-2654    

DOI:10.1039/AN994190089N

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, July 1994, Vol. 119 91N Conference Diary Date Conference Location Contact 1994 August 2-6 8-10 8-12 14-18 2 1-26 24-26 28-219 29-219 The Second Changchun International Symposium on Analytical Chemistry(C1SAC) China Changchun , 40th Canadian Spectroscopy Conference Halifax, Canada IGARSS '94: 1994 International Geoscience and Remote Sensing Symposium USA Pasadena , International Symposium on Bacterial Quebec, Polyhydroxyalkanotes (ISBP '94) Canada 208th ACS National Meeting (with Sessions of Washington, Analytical Chemistry, Environmental USA Chemistry, Chemical Health and Safety, etc ) International Symposium on Capillary Electrophoresis CLEO/EUROPE-EQEC European Conference on Lasers and Electro-Optics/ European Quantum Electronics Conference 13th International Mass Spectrometry Conference September 4-7 East European Furnace Symposium 5-6 First International Symposium on Neuroelectrochemistry 5-9 6-8 VIIth International Symposium on Synthetic Membranes in Science and Industry RSC Autumn Meeting (with Analytical Session on Analytical Challenges in Toxicology and Pollution) 8 Trace Analysis Symposium York, UK Amsterdam, Holland Budapest , Hungary Warsaw, Poland Coimbra, Portugal Tubingen, Germany Glasgow , UK London, UK 11-16 EUCMOS XXII: XXIInd European Congress Essen, on Molecular Spectroscopy Germany Professor Quinhan Jin, Department of Chemistry, Jilin University, Changchun 130023, China Tel: +86 431 82233 (ext.2433). Fax: +86 431 823907 Dr. W. D. Jamieson, Fenwick Laboratories Ltd., 5595 Fenwick Street, Suite 200, Halifax, NS B3H 4M2, Canada Tel: +1 902 420 0203.Fax: +1902 420 8612 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC 20036-1023, USA Tel: +1202 223 9034. Fax: +1202 416 6100 ISBP Secretariat, Conference Office, McGill University, 550 Sherbrooke St. West, West Tower, Suite 490, Montreal, Quebec, H3A 1R9, Canada Tel: +1514 398 3770. Fax: +1514 398 4854 Mr. B. R. Hodson, American Chemical Society, 1155-16th Street N.W., Washington, DC 20036, USA Dr. T. L. Threlfall, Industrial Liaison Executive, University of York, Department of Chemistry, Heslington, York, UK YO1 5DD Tel: +44 (0)904 432576. Fax: +44 (0)904 432516 Meetings and Conference Department, The Institute of Physics, 47 Belgrave Square, London, UK SWlX 8QX Tel: +44 (0)71235 6111.Fax: +44 (0)71 259 6002 Hungarian Chemical Society, H-1027 Budapest, Hungary Tel: +36 1201 6883. Fax: +36 1 15 61215 Dr. Ewa Bulska, University of Warsaw, Department of Chemistry, UI. Pasteura 1,02 093 Warsaw, Poland Fax: +48 22 225996 Profa. Dra. Ana Maria Oliveira Brett, Departamento de Quimica, Universidade de Coimbra, 3049 Coimbra, Portugal Tel: +35139 22826. Fax: +351 39 27703 Dechema, P.O. Box 970146, D-W-6000 Frankfurt am Main 97, Germany Dr. J. F. Gibson, The Royal Society of Chemistry, Burlington House, Piccadilly , London, UK W1V OBN Tel: +44 (0)71 437 8656. Fax: +44 (0)71 734 1227 Dr. Graham MacKay, Lab 6-10, Laboratory of the Government Chemist, Queens Road, Teddington, Middlesex, UK TWll OLY Tel: +44 (0)81 943 7496. GDCh-Geschiiftsstelle, Abt.Tagungen, Varrentrappestr. 40-42, Postfach 90 04 40, D-6000 Frankfurt am Main 90, Germany Tel: +49 69 79 17 358. Fax: +49 69 79 17 47592N Analyst, July 1994, Vol. 119 Date 12-15 12-15 12-15 13-14 13-18 14-15 18-22 19-20 19-21 19-21 19-23 21-23 2 1-24 22-24 25-28 26-28 26-30 Conference Separations for Biotechnology Location Reading, UK IIIrd International Symposium on Environmental Geochemistry Poland Krakow , The 108th AOAC International Annual Meeting and Exposition USA Portland, Recent Advances in Thermal Analysis Techniques UK Leeds , 3rd International Symposium on Mass Spectrometry in the Health and Life Sciences San Francisco, USA Waterborne Coatings and Additives Manchester, UK Geoanalysis 94: An International Symposium on the Analysis of Geological and Environmental Materials Ambleside, UK Chiral Europe '94 Nice , France The Second International Conference on Applications of Magnetic Resonance in Food Science The Fourth Annual CIM Field Conference Aveiro, Portugal Ontario, Canada XIIIth International Symposium on Medicinal Paris , Chemistry France 7th International Symposium on Bournemouth, Environmental Radiochemical Analysis UK 5th International Symposium on Stockholm, Pharmaceutical and Biomedical Analysis Sweden 12th National Conference on Analytical Chemistry Romania Cons tanta , 5th International Symposium on Chiral Discrimination Sweden Stockholm , Protozoan Parasites and Water York, UK Contact SCI Conference Office, 14/15 Belgrave Square, London, UK SWlX 8PS Tel: +44 (0)71 235 3681.Fax: +44 (0)71 823 1698 Helios Rybicka, Faculty of Geology, Geophysics and Environmental Protection, University of Mining and Metallurgy, Al.Mickiewicza 30, PL-30-059 Krakow, Poland Tel: +48 12 333290. Fax: +48 12 332936 Margaret Ridgell, AOAC International, 2200 Wilson Boulevard, Suite 400, Arlington, Tel: +1 703 522 3032. Edward Charsley/Stephen Warrington, Thermal Analysis Consultancy Service, Leeds Metropolitan University, Calverley Street, Leeds, UK LS13HE Tel: +44 (0)532 833121/833122. Fax: +44 (0)532 833120 Marilyn Schwartz, Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 9413-0446, USA Mrs. C. L. Sharp, Conference Secretary, 41 Exeter Road, Davyhulme, Manchester, UK M41 ORF Tel: +44 (0)61747 4961. Fax: +44 (0)61 747 4961 D.L. Miles, Analytical Geochemistry Group, British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, UK NG12 5GG Tel: +44 (0)602 363100. Fax: +44 (0)602 363200 Spring Innovations Ltd, 216 Moss Lane, Bramhall, Stockport, UK SK1 1BD Tel: +44 (0)61 440 0082. Fax: +44 (0)61 440 9127 Dr. A. M. Gil, Department of Chemistry, University of Aveiro, 3800 Aveiro, Portugal VA 22201-3301, USA 1994 CIM Field Conference, c/o Sudbury Geological Discussion Group, P.O. Box 1233, Station B, Sudbury, Ontario, Canada, P3E 4S7 CONVERGENCESASMC '94, 120 Avenue Gambetta, 75020 Paris, France Fax: +33 1 40 31 0165 Dr. P. Warwick, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, UK LEll 3TU Tel: +44 (0)509 222585. Fax: +44 (0)509 233163 Swedish Academy of Pharmaceutical Sciences, P.O.Box 1136, S-111 81 Stockholm, Sweden Tel: +46 8 245085. Fax: +46 8 205511 Dr. G.-L. Radu, Romanian Society of Analytical Chemistry 13 Bul. Carol I, Sector 3, 70346 Bucharest, Romania Swedish Academy of Pharmaceutical Sciences, P.O. Box 1136, S-111 81 Stockholm, Sweden Tel: +46 8 245085. Fax: +46 8 205511 IFAB Communications, Institute for Applied Biology, University of York, York, UK YO1 5DD Tel: +44 (0)904 432940. Fax: +44 (0)904 432917 16th International Symposium on Capillary Chromatography Italy 20, B-8500 Kortrijk, Belgium Riva del Garda, Professor Dr. P. Sandra, IOPMS, Kennedypark Tel: +32 56 204960. Fax: +32 56 204859Analyst, July 1994, Vol. 119 93N Date Conference Location Contact 29-30 Food and Feed Analysis: A Focus on Methods Nyon, with Mineral Hazards to Health and the Environment Switzerland October 2-7 29th Annual Meeting of the Federation of Analytical Chemistry and Spectroscopy USA Societies 3-6 PREP '94: 11th International Symposium on Baden-Baden, Preparative and Industrial Chromatography Germany St.Louis, MO, 10-13 International Symposium on Bled, Chromatographic and Electrophoretic Slovenia Techniques Traceability and Comparability of Analytical Measurements 14-15 CITAC '94 Hong Kong Symposium on Hong Kong 17-19 3rd International Symposium on Supercritical Strasbourg, Fluids 30-411 OPTCON '94 31-2/11 ANABIOTEC '94: 5th International Symposium on Analytical Methods, Systems and Strategies in Biotechnology November 6-12 9-1 1 1&11 18-22 24-26 1995 Third Rio Symposium on Atomic Spectrometry 11th Montreux Symposium on Liquid Chromatography-Mass Spectrometry (LCI MS; SFC/MS; CE/MS; MS/MS) 17th International Conference on Chemistry, Bio Sciences, and Environmental Pollution Joint Oil Analysis Program International Condition Monitoring Conference 5th International Symposium on Advances in Electrochemical Science and Technology January 8-13 1995 Winter Conference on Plasma Spectrochemistry France Boston, USA Minneapolis, USA Caracas, Venezuela Montreux, Switzerland New Delhi, India Pensacola, FL, USA Madras, India T.Rihs, Swiss Federal Research Station for Animal Production, CH-1725 Posieux, Switzerland Tel: +41 37 877 111. FACSS, P.O. Box 278, Manhattan, KS 66502- 0003, USA Tel: + 1 301 846 4797. GDCh-Geschiiftsstelle, Abt.Tagungen, Varrentrappestr. 40-42, Postfach 90 04 40, D- 6000 Frankfurt am Main 90, Germany Tel: +49 69 79 17 358. Fax: +49 69 79 17 475 Dr. M. ProSek, National Institute of Chemistry, SLO-Ljubljana, Slovenia Fax: 386 61 12 59 244 Dr. T. L. Ting, CITAC '94 Secretariat, c/o Government Laboratory, Ho Man Tin Government Offices, 88 Chung Hau Street, Hong Kong Tel: +852 762 3706. Fax: +852 714 4083 Congres 'Fluides Supercritiques' Mle Brionne, ENSIC B.P. 451-1, rue Grandville, F-54001 Nancy Cedex, France Tel: +33 83 17 50 03. Fax: +33 83 35 08 11 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC 20036-1023, USA Tel: + 1 202 223 9034. Fax: + 1 202 416 6100 Anabiotec Conference Secretariat, Elsevier Advanced Technology, Mayfield House, 256 Banbury Road, Oxford, UK OX2 7DH Tel: +44 (0)865 512242.Fax: +44 (0)865 310981 Professor JosC Alvarado, Universidad Simon Bolivar, Departamento de Quimica, Laboratorio de Absorcion Atomica, Apartado Postal No. 89000, Caracas, 1080-A, Venezuela Fax: + 58 2 938322/5719134/5763355/9621695 M. Frei-Hausler, Postfach 46, CH-4123 Allschwil 2, Switzerland Tel: +41614812789. Fax: +41 61 4820805 Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5V7 Tel: +1613 932 7702. Technical Support Center, Joint Oil Analysis Program, Bldg. 780, Naval Air Station, Pensacola, 'FL 32508, USA Tel: +1 904 452 3191. The Secretary, Society for Advancement of Electrochemical Science and Technology, Karaikudi, 623 006, India Cambridge, UK Janice M.Gordon, Winter Conference on Plasma Spectrochemistry , Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge, UK CB4 4wF Tel: +44 (0)223 420066. Fax: +44 (0)223 42024794N Analyst, July 1994, Vol. 119 Date Conference February 15 19-24 April 10-13 May 7-1 1 2 1-26 21-26 June 5-8 July 9-15 10-13 Alternatives to Chemical Solvents Restricted by the Montreal Protocol OFC '95: Optical Fibre Communication Conference Annual Chemical Congress (with Analytical Session) Seventeenth International Symposium on Capillary Chromatography and Electrophoresis CLEO '95: Conference on Lasers and Electro-Optics QELS '95: Quantum Electronics and Laser Science Conference 5th Symposium on our Environment and 1st Asia-Pacific Workshop on Pesticides SAC 95 Vth COMTOX Symposium on Toxicology and Clinical Chemistry of Metals August 27-219 CSI XXIX: Colloquium Spectroscopicum Internationale 27-1/9 46th Annual Meeting of the International Society of Electrochemistry (ISE46) Location London, UK San Diego, USA Edinburgh, UK Virginia, USA Baltimore, USA Baltimore, USA Convention City, Singapore Hull, UK Vancouver, Canada Leipzig, Germany Xiamen, China Contact Ms.Paula Elliott, Secretary, Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 (0)71 437 8656. Fax: +44 (0)71 734 1227 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC 20036-1023, USA Tel: +1 202 223 9034. Fax: +1202 416 6100 Dr.J. F. Gibson, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 (0)71437 8656. Fax: +44 (0)71 734 1227 Dr. Milton L. Lee, Department of Chemistry, Brigham Young University, Provo, Tel: +1 801 378 2135. Fax: +1801378 5474 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC 20036-1023, USA Tel: +1 202 223 9034. Fax: +1202 416 6100 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC 20036-1023, USA. Tel: +1202 223 9034. Fax: +1 202 416 6100 UT 84602-4672, USA The Secretariat, 5th Symposium on our Environment, c/o Department of Chemistry, National University of Singapore, Kent Ridge, Republic of Singapore 0511 Fax: +65 779 1691 Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly , London, UK W1V OBN Tel: +44 (0)71 437 8656.Fax: +44 (0)71 734 1227 F. William Sunderman, Jr., M.D., Departments of Laboratory Medicine and Pharmacology, University of Connecticut Medical School, P.O. Box 1292, Farmington, CT 06034-1292, USA Tel: + 1 203 679 2328. Fax: + 1 203 679 2154 GDCh-Geschiiftsstelle, Abt. Tagungen, Varrentrappestr. 40-42, Postfach 90 04 40, D-6000 Frankfurt am Main 90, Germany Tel: +49 69 79 17 358/360/366. Fax: +49 69 79 17 475 Secretariat, XLVIth ISE Annual Meeting, P.O. Box 1995, Xiamen University, Xiamen 361005, China Tel: +86 592 2085349. Fax: +86 592 2088054Analyst, July 1994, Vol. 119 95N Date Conference Location Contact September 25-28 5th Symposium on ‘Kinetics in Analytical Moscow, Dr.I. F. Dolmanova, Analytical Chemistry Moscow State University, 119899 Moscow, Russia Tel: +7 095 939 33 46. Fax: +7 095 939 25 79 Chemistry’ (KAC ’95) Russia Division, Chemical Department, Lomonosov October 1-5 21st World Congress of the International The Hague, Mrs. J. Wills, ISF Secretariat, P.O. Box 3489, Champaign, IL 61826-3489, USA Tel: +217/359 2344. Fax: +217/351 8091 Society for Fat Research (ISF) The Netherlands November 5-10 OPTCON’95 1996 February 6-9 June 16-21 8-12 1-7 15-20 San Jose, USA Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC 20036-1023, USA Tel: +1 202 223 9034. Fax: +1 202 416 6100 Fourth International Symposium on Bruges, Hyphenated Techniques in Chromatography Belgium (HTC 4); Hyphenated Chromatographic Analysers HPLC ’96: 20th International Symposium on High Performance Liquid Chromatography USA San Francisco, XVI International Congress of Clinical Chemistry UK London, Euroanalysis IX Bologna, Italy 21st International Symposium on S tu ttgart , Chromatography Germany Dr. R. Smits, Royal Flemish Chemical Society (KVCV), Working Party on Chromatography, BASF Antwerpen N.V., Central Laboratory, Haven 725, Scheldelaan 600, B-2040 Antwerp, Belgium Tel: +32 3 561 28 31. Fax: +32 3 561 32 50 Mrs. Janet Cunningham, Barr Enterprises, P.O. Box 279, Walkersville, MD 21793, USA Tel: +1301898 3772. Fax: +1301898 5596 Mrs. Pat Nielsen, XVIth International Congress of Clinical Chemistry, P.O. Box 227, Buckingham, UK MK18 5PN Fax: +44 (0)280 6487 Professor Luigia Sabbatini, Euroanalysis IX, Dipartimento di Chimica, Universita di Bari, Via Orabona, 4, 70126 Bari, Italy Tel: +39 80 242020/16/14. Fax: +39 80 242026 GDCh-Geschiiftsstelle , Ab t . Tagungen , Varrentrappestr. 40-42, Postfach 90 04 40, D-6000 Frankfurt am Main 90, Germany Tel: +49 69 79 17 358/360/366. Fax: +49 69 79 17 475

ISSN:0003-2654    

DOI:10.1039/AN994190091N

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

96N Analyst, July 1994, Vol. 119 Courses Date Conference Location Contact 1994 August 21-24 Capillary Electrophoresis Course September 4-8 Molecular Graphics and Modelling Short Course 5 4 Workshop on Evaluation of Measurement Uncertainty in Chemical Analysis 5-9 AMCP-AES-ICP-MS Short Course 6-8 5th Workshop on Chemistry and Fate of Modern Pesticides 6-9 The Lee& Course in Clinical Nutrition 21-22 Statistical Tools for Analytical Quality Assurance Workshop 25-30 1994 European Workshop in Chemometrics October 18-19 Mass Spectrometry for Beginners November 7-8 Short Course on LC/MS, SFC/MS and cms December 15-17 Capillary Electrophoresis Short Course York, UK York, UK Graz , Austria Loughborough, UK Paris, France Leeds, UK London, UK Bristol, UK Manchester, UK Montreux, Switzerland Loughborough, UK Dr.T. L. Threlfall, Industrial Liaison Executive, University of York, Department of Chemistry, Heslington, York, UK YO1 5DD Tel: +44 (0)904 432576. Fax: +44 (0)904 432516 Dr. T. L. Threlfall, Industrial Liaison Executive, University of York, Department of Chemistry, Heslington, York, UK YO1 5DD Tel: +44 (0)904 432576. Fax: +44 (0)904 432516 Professor W. Wegscheider, Technische Universitat Graz, TechnikerstraB 4, A-8010 Graz, Austria Tel: +43 316 873 8303. Fax: +43 316 810926 Mrs. S. J. Maddison, Department of Chemistry, Loughborough, University of Technology, Loughborough, Leicestershire, UK L E l l 3TU Tel: +44 (0)509 22575. Professor M-C. Hennion, ESPCI, L a b . Chimie Analytique, 10 rue Vauquelin, 75005 Paris, France Mrs. Hilary L.Thackray, Department of Continuing Professional Education, Continuing Education Building, Springfield Mount, Leeds, UK LS2 9NG Tel: +44 (0)532 333233. Leslie Coveney, 144 Porstmouth Road, Cobham, Surrey, UK KTll 1HX Tel: +44 (0)32 864 915. Fax: +44 (0)32 864 915 Janice Green, School of Chemistry, University of Bristol, Cantock’s Close, Bristol, UK BS8 1TS Tel: +44 (0)272 303030 (ext. 4421) or +44 (0)272 303672. Fax: +44 (0)272 251295 Dr. M. P. Coward, Chemistry Dept. UMIST, P.O. Box 88, Manchester, UK M60 1QD Tel: +44 (0)61 200 4491. Fax: +44 (0)61 228 1250 M. Frei-Hausler, Workshop Office IAEAC, Postfach 46, CH-4123 Allschwil 2, Switzerland Mrs. S. J. Maddison, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, UK L E l l 3TU Tel: +44 (0)509 22575. Entries in the above listing are included 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/AN994190096N

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, July 1994, Vol. 119 97N Future Issues will lnclude- Determination of Ceftriaxone in Aqueous Humour and Serum Samples by Differential-pulse Adsorptive Stripping Voltammetry-Aytekin Temizer, Sacide Altinoz, Durisehvar Ozer and Nursen Yuksel Direct Analysis of Milk for Aluminium Using Electrothermal Atomic Absorption Spectrometry-Miguel ValcBrcel, Marco A. Z. Arruda, Ma. Jod Quintela and Mercedes Gallego Sensitive Spectrophotometric Determination of Zirconium With p-Acetylchlorophosphonazo in the Presence of Sodium Dodecylbenzenesulfonate-Qing-Zhou Zhai Derivative Fourier Transform Infrared Spectrometric Deter- mination of Ethanol in Beers-Miguel de la Guardia, Maiximo Gallignani and Salvador Garrigues Spectrophotometric Method for the Determination of Total Tobacco Alkaloids and Nicotine-V.K. Gupta and Manish Rai Ramachandran 4-[ 1 -Methyl-2-phenanthra-( 9,lO)-( + ) -imidazoyl] benzo- hydrazide as Derivatization Reagent for Carboxylic Acids in High-performance Liquid Chromatography With Conven- tional and Laser-induced Fluorescence Detection-Masatoshi Yamaguchi, Tetsuharu Iwata, Tsuyoshi Hirose and Masaru Nakamura Comparison of Two Digestion Methods for the Determination Selenium in Biological Samples-Veronique Ducros, Daniel Ruffieux, Nicole Belin and Alain Favier Characterization of Hydrogenated Derivatives of Methyl- and Dimethyldicyclopentadiene Isomers by Gas Chroma- tography-Mass Spectrometry and Carbon-13 Nuclear Magne- tic Resonance Spectroscopy-D. Nicole, F. Schmit-QuiPs and J.-C. Lauer Automated Determination of Weakly Acidic and Basic Pollutants in Surface Water by On-line Electrodyalysis Sample Treatment and Column Liquid Chromatography- Nico C.Van de Merbel, Matthieu G. M. Groenewegen, Jaroslav Slobodnik, Henk Lingeman and Udo A. Th. Brinkman Continuous-flow System for the Accurate Determination of Low Concentrations of Ammonium Ions Using a Gas- permeable Poly(tetrafluoroethy1ene) Tube Decontaminator and an Ammonia Gas-sensing Membrane Electrode-Hirok- azu and Susumo Matsumoto Silica Gel Modified With Zincon as a Sorbent for Preconcen- tration or Elimination of Trace Metals-Ryszard Kocjan Immunoassay for Parathion Without its Prior Removal From Solution in Hexane-John M. Francis and Derek H. Craston Sensitive Determination of Periodate and Tartaric Acid by Stopped-flow Chemiluminescence Spectrometry-Dolores Pkrez-Bendito, Abaji Gaikwad and Manuel Silva COPIES OF CITED ARTICLES The Royal Society of Chemistry Library can usually supply copies of cited articles.For further details contact: The Library, Royal Society of Chemistry, Burlington House, Piccadilly, London W1V OBN, UK. Tel: +44 (0)71-437 8656. Fax: +44 (0)71-287 9798. Telecom Gold 84: BUR210. Electronic Mailbox (Internet) LIBRARY@RSC.ORG. If the material is not available from the Society’s Library, the staff will be pleased to advise on its availability from other sources. Please note that copies are not available from the RSC at Thomas Graham House, Cambridge.GEOANALYSIS 94 An International Conference on the Analysis of Geological and Environmental Materials 18-22 September 1994 Ambleside, UK You are invited to participate in GEOANALYSIS 94, an International Symposium covering all aspects of the analysis of geological and environmental materials.GEOANALYSIS 94 is designed to attract international participation from scientists in Universities, Research Institutes, Commercial and Industrial Laboratories interested in any aspect of the development and application of analytical techniques in geochemistry and the environmental sciences. Plenary lecture: K. Govindaraju (France) Expanding IWG- GIT Geostan Databases Invited speakers will include: G E M Hall (Canada) The great leap forward: hydrogeochemical surveys K G Heumann (Germany) Developments in thermal ionization techniques for isotope analysis G Remond (France) Standards for microbeam techniques: application of ion implantation J V Smith (USA) Synchrotron X-ray sources: new applications in microanalysis, tomography, absorption spectrometry and diffraction I Thornton (England) Challenges to the analyst in the assessment of contaminated land J S Kane (USA) Impact of ICP-MS on certification programmes for geochemical reference materials R K O’Nions (England) New applications of SIMS to problems in earth and ocean sciences J C Rucklidge (Canada) Accelerator mass spectrometry in environmental geoscience-a new frontier M Thompson (England) International progress towards a unijied system of concepts and practices for data quality R J Watling (Australia) Analysis of diamonds and indicator minerals for diamond exploration by laser ablation ICP-MS LOCATION The Charlotte Mason Conference centre in Ambleside lies in the heart of the English Lake District near to the shores of Lake Windermere.This purpose-built conference centre offers both luxury bedrooms and more economical accommodation on site, all within easy walking distance of lecture theatres, dining areas and sports facilities. POST-CONFERENCE WORKSHOPS AND FIELD TRIPS (a) Lake District Field Trip (b) Quality Assurance and Laboratory Accreditation (c) Geological Reference Materials - a practical guide to their preparation, characterization and evaluation DEADLINES AND KEY DATES Deadline for the submission of abstracts Acceptance of oral and poster contributions will be mailed to delegates by Deadline for registration at the discounted rate ( A surcharge is payable for registrations received after this date) Mailing of joining instructions to those who have registered 15 April 1994 15 May 1994 30 June 1994 15 August 1994 EXHIBITION An exhibition of instruments, laboratory supplies and books will accompany the conference. FOR FURTHER INFORMATION CONTACT: Doug Miles, GEOANALYSIS 94 Conference Secretariat, Analytical Geochemistry Group, British Geological Survey, Keyworth, Nottingham NG12 5GG, UK. Tel: +44 (0)602 362349; Fax: +44 (0)602 363200; Telex: 378173 BGSKEY G; E-mail: K-SNRC@UK.AC.NERC-KEYWORTH.VAXA Principal Sponsor: The RTZ Corporation PLC -L

ISSN:0003-2654    

DOI:10.1039/AN994190097N

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, July 1994, Vol. 119 1429 ~ Derivatization by Ethylation With Sodium Tetraethylborate for the Speciation of Metals and Organometallics in Environmental Samples A Review Spyridon Rapsomanikis Biogeochemistry Department, Max Planck Institute for Chemistry, P. 0. Box 3060, 55020 Mainz, Germany Summary of Contents Introduction Lead and alkylleads Mercury and methylmercury Tin and organotin compounds Cadmium Other metals Conclusion References Keywords: Ethylation; sodium tetraethylborate; metals and organometallics; speciation; environmental samples Introduction Publications on the chemistry of organoborates have appeared sporadically since the end of the last century. Aryl or alkyl group transfer from a monosubstituted aryl or alkyl boronic acid [RB(OH)2] to the mercury of HgC12 in aqueous media has been disc~ssed.~-~ Honeycutt and Riddle8 reported the transfer of two ethyl groups to the mercury centre from triethylborate in aqueous and organic media.In a more complete publication,g they reported that various Hg and Pb salts react with R3B compounds to yield fully alkylated metal species in a number of solvents and with varying yields (Table 1). Higher yields are produced in aqueous alkaline media and the stepwise [reactions (1) and (2)] and overall reactions with HgCI2 [reaction (3)] proceed as follows: R3B + HgCI2 + 2NaOH -+ R2BONa + RHgCl R2BONa + RHgCl + 2NaOH -+ RB(ONa)2 + R2Hg R3B + HgCI2 + 4NaOH -+ RB(ONa)2 + R2Hg + 2NaCl Alternatively, if exhaustive dealkylation of R3B occurs, the overall reaction can be expressed as 2R3B + 3HgCI2 + 12NaOH -+ 3R2Hg + 2B(ONa)3 + 6NaC1 The equivalent exhaustive dealkylation of R3B during its reaction with PbO may proceed as follows: 2R3B + 3Pb0 + 6NaOH -+ 3R2Pb + 2B(ONa)3 + NaCl + H20 (1) + NaCl + H20 (2) + 2H20 (3) + 6Hz0 (4) + 3H2O (5) 3R2Pb -+ 3/2 R4Pb + 3/2 Pb It is not clear which stoichiometry the authors had in mind when they quoted yields of R4Pb, as it is clear from reactions (5) and (6) that only half the initial molar amount of Pb can yield &Pb.Honeycutt and Riddlelo subsequently proceeded to the preparation and reactions of tetraethylborate and related compounds in a quest for efficient transfer of ethyl groups to the metal centre. NaBR(C2H5)3 (R = H, Et, Bu, Ph) compounds were prepared and their chemical and physical properties investigated. A number of synthetic pathways were followed, some needing high-pressure reactors and some only ordinary laboratory glassware.Rapsomanikis et al. 11 successfully synthesized NaB(C2H5), (STEB) using C2HSC1, Na sand and commercially available (6) Table 1 Ethylation reaction conditions and yields using R3B R in R3B Amount of R3B/mol Metal compound 0.05 0.05 0.02 0.07 0.07 0.13 0.07 0.055 0.028 0.028 0.02 0.05 0.13 Amount of metal compound/mol 0.05 0.05 0.04 0.035 0.03 0.06 0.035 0.055 0.02 0.02 0.01 0.05 0.13 Solvent H20-NaOH H20-NaOH THFt THF H20-NaOH H20 H20-NaOH THF (CH30CH2)2 (CH30CH2)2 (CH30CH2)2 H20-NaOH (CH30CH212 Yield (%) 95 65 66 54 27 42 19 55 50 52 18 52 47 * Lead naphthenate. + Tetrahydrofuran.1430 Analyst, July 1994, Vol. 11 9 B(C2Hs)3 in diethyl ether under a nitrogen atmosphere.The reaction and reflux vessels should, however, be leak-tight because B(C2Hs)3 is pyrophoric on contact with air. Another ~~ ~~ ~~ Table 2 Infrared band positions of NaBR4 compounds. Samples prepared in an inert atmosphere. Intensities indicated as very strong (vs), strong (s), medium (m), weak (w) and shoulder (sh). Wave- lengths in pm NaB(C6H5) NaB(C2H5)4* (C2H5)3*’t NaBH4* NaB ( C~HS)~HS 3.5(s) 3.5(s) 3 3 s ) 4.25(sh) 4.52( w) 4.40(s) 5.4( vs, broad) 6.85(s) 6.87( s) 6.87( s) 7.36(w) 7.35(w) 7.30(w) 7.90( m) 7.96(m) 7.90( m) 8.16(w) 8.18(w) 8.90(s) 9.34(s) 9.55(s) 9.30(s) 10.90( s) 10.30(w) 11.36(s) 11.66(s) 11.70( m) 12.60( m) 1 1.50(s, broad) * Run as KBr disc. t B-phenyl absorptions, as in NaB(C6H5)4, not listed.Run as a smear. Table 3 Per cent. hydrolysis of tetraalkylboron compounds. Percen- tage hydrolysis is calculated on the basis of 4 mol of theoretical alkane for each mole of tetraalkylboron compound NaOH solution, Tetraalkylboron H20, 35 “C pH 10,35 “C 20% HOAc, compound 16h 16 h 60°C. 1 h Li (C2H5)3B (c4H9) 29.2 Li(C4H914B 13 15.9 24.5 Li(C2H5)3BC12H25 12* 12.5* 33.lt Li(C4H9)3BC12H2s 12.8* 11.1* 36.5t (CH3)4NB(C4H9)4 0.45 0.0 5 s * Based on per cent. of gas only. + Based on per cent. of gas and dodecane. t The extreme sensitivity of tetramethylammonium tetrabutylboron to acetic acid has not been studied. i I Time/min - Fig. 1 Chromatogram of ethylated derivatives of Me3Pb+, Me2Pb2+ and Pb2+ (as pg Pb): (2) Me3EtPb (50 pg); (3) Me2Et2Pb (50 pg); and (5) Et4Pb (3000 pg).Reproduced with permission from ref. 14. word of caution concerns the glassware used for the synthetic work and the heated vacuum desiccator for the purification of the NaB(C2H5)4 etherate. They should be extremely clean because contamination of NaB(C2Hs)4 from metal com- pounds abundant in a synthetic laboratory will lead to analytical artefacts. The important highlights of Honeycutt and Riddle’s work are that the superhydride [NaB(C2H5)3H] dismutates to give NaBH4 and NaB(C2Hs)4 and that NaB(C2Hs)3(C4H9) on acid hydrolysis with HCl liberates both ethane and butane, indicating that not one specific trialkylborate remains in solution. Further, they also showed that NaB(C2Hs)4 under a variety of reaction conditions ethylates Pb(OAc)2, PbCI2, PbO and Pb(S04)2.In aqueous solutions and at temperatures between 25 and 100°C, all lead salts give quantitative yields of the expected (C2Hs)4Pb (up to 98%) based on the stoichiometry of the following reaction: 4NaB(C2Hs)4 + 2Pb2+ -+ (C2Hs)4Pb + 4(C2H5)3B + Pb + 4Na+ (7) However, as (C2Hs)3B also alkylates Pb salts as in reactions (5) and (6), a higher molar amount of starting Pb2+ will yield additional tetraethyllead from each mole of NaB(C2HS),. Infrared absorption bands of the NaB(C2Hs)3R (R = Et, Ph, H) compounds synthesized by Honeycutt and Riddlelo are listed in Table 2. A number of lithium and sodium tetraalkylborates were synthesized by Damico,12 using the direct reaction of R3B and MR’ according to the general reaction (8) in alkane solvents. alkane MR’ + R3B - + MR3BR’ (8) Time/min 4 Fig.2 Chromatograms of headspace from (a) ethylated sediment sample and ( 6 ) ethylated sediment sample spiked with MeHg+. Peak at 2.33 min is MeHgEt and peak at 4.33 min is Et2Hg. Unpublished results, University of New Hampshire, 1984.Analyst, July 1994, Vol. 119 143 1 The compounds synthesized were Li( C2H&BC4H9, Na(C4H9)4B and Na(C2H5)3BC12H25, but the use of alkane solvents is not optimum for giving high yields of the sodium compounds. The major infrared absorption bands were identified together with molar absorptivities at about 2800 cm-l due to methylene groups. Proton nuclear magnetic resonance (*H NMR) chemical shifts of the a-methylene groups relative to tetramethylsilane were also reported. 10 The Li(C4H9)4B Li(C2H5)3BC12H25 Li(C4H913BCI2H25 A 5 & B C D I I I I I I 0 4 8 12 16 20 Time/min Fig.3 HPLC-AAS traces of 0.1,0.3 and 5 ng each of: A , Me,Pb+; B, Et3Pb+; C, Me2Pb2+; and D, Et,Pb*+ recorded under conditions of optimum sensitivity. Reproduced with permission from ref. 17. HPLC eluate 1 3 t above tetraalkylborates were converted into their tetra- methylammonium or tetrabutylphosphonium salts because these were more stable to moisture and air. They were precipitated in aqueous solutions from the original sodium or lithium tetraalkylborates in quantitative yields according to the following general reaction: where M = Li or Na, R‘ = C4H9 or C12H25, R = C2H5 or C4H9 and C = (CH3)4N or (C4H9)4P. Hydrolysis rates were also studied at three different pH values10 and the results are presented in Table 3.It can be assumed that NaB(C2H5)4 has a similar hydrolysis rate but data do not exist. Further, Damico postulated that the hydrolysis of these compounds involved rapid proton attack at the electron rich a-carbon atom, loss of alkane and slow hydrolysis of the resulting trialkylborates: MR’BR3 + CBr + CR’BR3 + MBr (9) fast MBR4 + AcOH +MOAC + R3B + RH (lo) slow R3B + 3AcOH +B(OAC)~ + 3RH (11) The mechanism of the oxidation of tetraalkylborates was also postulated to involve an initial molecular oxygen attack on the a-carbon resulting in insertion of two oxygen atoms between the boron and carbon atoms. For example, oxidation of LiB(C4H9)4 in tetrahydrofuran (THF) at 35% for 16 h followed by base hydrolysis yielded the following percentages of the expected theoretical amounts: 48% butan-1-01, 3% butylaldehyde and 15% butane.A different synthetic strategy was followed by Thompson and Davis13 in a study of electronegativity effects on the IlB chemical shifts in tetrahedral BX4- ions. They carried out the reaction of BF3 with the appropriate alkyl Grignard reagent in etherate solutions. They were unsuccessful in isolating LiBR4 (R = ethyl, propyl, butyl) but the etherate solutions of the above-formed alkylborates showed 11B NMR spectra with very similar chemical shifts. A relationship between the electronegativity of the anionic group and the 1lB chemical shifts in BX4- ions was also identified. In a repeat exercise, Binger and Koester14 synthesized NaB(C2H5), using the NaHB(C2H5)3 reaction with ethylene gas method of Honey- cutt and Riddle: NaHB(C2H5)3 + C2H4 + NaB(C2H5), (12) They confirmed that the addition of B(C2H5)3 to the reaction autoclave was desirable but not essential, suggesting an initial n B + QTAAS U t NaBEt, solution Fig.4 Post-column reactor assembly consisting of a mixing T, 3 mm i.d. capillary PTFE tube (A) connected via heating coil (B) to a gas- liquid separator (E). Gaseous effluent was channelled from the GLS to the quartz T-tube via a 0.32 mm i.d. fused silica transfer line (G). Reproduced with permission from ref. 17.1432 Analyst, July 1994, Vol. 119 5 3 1 Solvent Time/min Table 4 Effect of contaminating metals on tetraethyllead production Contami- Concentra- nant tionlng g-I n 2 None - Fe 18.9 3 161 .O 3 Zn 18.9 3 161 .O 3 c u 18.9 3 161 .O 3 Pb added1 A295* ng g-It 19345 19.5 22206 19.5 9976 16.6 22813 19.5 20775 16.6 2220 19.5 1808 16.6 Pb measuredl ng g-lt 21.2 20.5 17.9 21 .o 17.8 23.2 22.1 * Average area (arbitrary units) of peak at mlz 295 t Nominal Pb concentration calculated from amount of added t Pb concentration determined by standard procedure (see (triethyl-*osPb+).standard. Experimental). 60 50 40 30 I" 20 2 10 E n c3) Q -0 0 ' I I I 8 - 1 3 5 7 9 110 5 10 15 20 25 2 Solution pH Reaction time/min e 5 r" 40 - E 50 > 30 20 10 0 Fig. 5 2 4 6 8 100 5 10 15 20 25 Final tetraethylborate Bubbling time/min concentration/mg I-' Optimization of ethylation parameters: (a) effect of pH, (b) effect of ethylation time before bubbling, (c) effect of sodium tetraethylborate concentrations in reaction flask, and (d) effect of bubbling time.Line at 54.7 ng recovery indicates addition (expected yield). Error bars represent the standard deviation of 9-11 replicates. Reproduced with permission from ref. 18. I I Fig. 6 Conventional gas chromatograph connected to the quartz furnace atomizer of the atomic absorption spectrometer via a heated transfer line. HCL, hollow cathode lamp. Reproduced with permis- sion from ref. 22. step of ethyl formation from the hydrogen of the superhydride and ethene and subsequent or concurrent addition to the boron centre of a triethylborate molecule. They also con- firmed the high yields and product purity of this process. With the chemistry of alkyl transfer from alkylborates to a metal centre outlined above in mind, Rapsomanikis et al.11 attempted the ethylation of ionic methyllead and methylmer- cury compounds in aqueous solutions.The hypothesis was that the hydrides of these compounds may be too unstable to be reliably used as derivatives for analytical purposes. However, if formed in aqueous solutions, the ethyls can be stripped to a cryogenic trap, separated and analysed in situ with an atomic-specific detector as the hydride derivatives of other metals are handled. The prevailing methods involving extraction from aqueous solution into an organic solvent, drying, derivatization with a Grignard reagent, destroying the excess of reagent and finally performing the analysis, were tedious and necessitated a number of handling steps. They were hence conducive to analytical error.For the study described in ref. 11 the NaB(C2H5), reagent was synthesized in the laboratory, exploiting the direct reaction [eqn. (S)]. However, during the course of the analytical optimization experiments, STEB became commer- cially available. Lead and Alkylleads Determination and speciation of ionic alkyllead compounds have presented the analytical chemist with a serious challenge. In the environment, these compounds have an anthropogenic origin but they may also be produced from biological transformations of Pb2+. A number of methods can be employed for their determination but none is completely satisfactory. Differential-pulse anodic stripping voltammetry (DPASV) necessitates the use of pure solutions without interfering ions and preferably in the absence of Pb2+.A second method, ultraviolet (UV) spectrophotometric deter- mination after complexation with dithizone, is not sensitive and requires peak resolution. A third possibility involves butylation by Grignard reagents and chromatography coupled to atomic absorption spectrometry (AAS). It requires sample preconcentration and transfers, restricts the volume analysed (microlitres are injected into the chromatographic column) and demands considerable operator time and effort. For the 2 IAnalyst, July 1994, Vol. 119 1433 speciation of lead and mercury, at the time that the investigation described in ref. 11 took place, there existed no equivalent method to the hydride generation method, employed for the determination of inorganic and organome- t a l k compounds of Sn, Ge, As, Sb, Se and Te.The hydrides of lead and mercury organometallic compounds are not very stable, are prone to dismutation reactions and hence are not recommended for accurate analysis of environmental samples. No alternative derivatization reaction was satisfactory for the t - 2 w (I) .- E k 1 2 Ti me/m i n Fig. 8 Chromatogram of TORT-1. The measurement was per- formed with a freshly prepared NaB(C2H5), solution: A, non-specific; B, HgO; C, Me2Hg; D , MeHgEt; and E, Et2Hg. Reproduced with permission from ref. 24. in situ determination of ionic methyllead and methylmercury compounds. The process of ethylation by ethylborates remained a curiosity but also represented the only reported organometallic reaction taking place in aqueous media.Thus, with a large number of unknown parameters to optimize, Rapsomanikis et al.11 set out to try the analytical application of the ethylation reaction on aqueous standards of ionic methyl- lead and methylmercury compounds. The synthesized NaB(C2Hs)4 was utilized in a purge and trapatomic absorp- tion apparatus. The rate constant of the reaction, the optimum pH and the optimum gas flow rates for the separation of the derivatives prior to AAS detection were unknown. A protracted and detailed study of the reaction could have defined the above parameters but the fastest way to optimize an experimental system, i.e., by the simplex algorithm, was employed. In the absence of commercially available programs we developed and utilized a computer program based on the algorithm of Nelder and Mead.15 As a result, the peak height of derivatized (CH3)3Pb+ was maximum for the following values of five variables: (1) initial pH 4.1; (2) 3 ml of 0.43% m/ v aqueous STEB added; (3) 8.7 min reaction purge time; (4) 102 ml min-1 helium carrier gas flow rate; and ( 5 ) 18 ml min-l H2 added gas flow rate.Absolute detection limits for a 50 ml sample were approximately 10 pg of Pb as (CH3)3PbC2H5 or (CH3)2Pb(C2Hs)2. Methyl and inorganic lead and mercury compounds were derivatized, separated and quantified in situ (Fig. 1). The reactions that took place in aqueous solutions were reactions (7) and perhaps ( 5 ) and (6) for the derivatiza- tion of inorganic Pb2+ to tetraethyllead, but also (CH3)3Pb+ + NaB(C2H& -+ (CH3)3PbC2H5 + Na+ (CH3)2Pb2+ + 2 NaB(C2H& -+ (CH3)2Pb(C2H5)2 + 2Na+ + For the derivatization of Hg2+ the following reaction may have taken place: -k B(C2HS)3 (13) 2B(C2HS)3 (14) Hg2+ -k 2NaB(C2H5)4 (C2H5)2Hg + B(C2H5)3 + 2 Na+ (15) and perhaps reaction (4).For the derivatization of CH3Hg+ the following reaction may have taken place: CH3Hg+ + N ~ B ( C ~ H S ) ~ -+ CH3HgC2H5 + B ( C ~ H S ) ~ and possibly 3CH3Hg+ + B(C2H5)3 + 6NaOH + 3CH3HgC2H~ + B(ONa)3 + 3Na+ + 3H20 (17) However, the derivatized mercury compounds were not analysed with the same experimental apparatus as the lead compounds. Only the headspace of sealed vials was analysed by gas chromatography (GC) to demonstrate the reaction feasibility and applicability to environmental samples (Fig. 2). Sturgeon et al.16 improved the sensitivity of AAS for Pb by generating (C2H5)4Pb from Pb2+ according to reaction (7) and depositing it on the hot surface of the graphite furnace.The reaction and detection conditions were optimized but the optima were not different to those published by Rapsomanikis et aZ.11 for lead ethylation. Absolute detection limits were also + Na+ (16) Table 5 Results of methylmercury determination in fish tissues. The figures in parentheses are the number of determinations Measured MeHg+ Standard deviation/ Relative standard 95% confidence limit/ Certified MeHg+ Sample value/pg g-l Hg* I43 g- Hg* deviation (YO) Clgg-lHg value/pgg-' Hgt TORT- 1 0.133 (3) 0.011 8.2 0.047 0.128 k 0.014 DORM-1 0.766 (3) 0.047 6.1 0.201 0.731 k 0.060 DOLT-1 0.074 (3) 0.012 16.2 0.052 0.080 * 0.011 * Dry mass.t Certified value k 95% confidence limit.1434 Analyst, July 1994, Vol. 11 9 loo I similar and the applicability of the method was demonstrated with the analysis of marine reference materials for total Pb. Sturgeon et al.16 also noted that the derivatization method does not suffer a decrease in signal due to the presence of a large excess (106-fold) of Ca2+, Na+ and Mg2+ or a 5000-fold excess of Fe3+, Cfi+, Ni2+, Mn2+, AP+ and Zn2+. The only interfering element was Cu2+ at a 1000-fold excess (1 mg absolute amount), resulting in 15% decrease in signal. The limitation of the ethylation method for the determination of ionic alkylleads in the environment is that some ethyl- or mixed ethylmethyllead compounds already exist in nature, originating from gasoline anti-knock additives.Derivatization by ethylation results in a loss of information about the original identity of the ionic alkyllead compound. This drawback was 79 233 55 149 26 1 I 31 5 121 d 1 100 300 200 m/z Fig. 9 Mass spectrum of (C6H12)2Sn(C2H5)2. Reproduced with permission from ref. 27. 100 h 8 8 Y m U 5 50 9 a .- 4- - a a 0 207 Fig. 12 with permission from ref. 28. Glass reactor for organotin ethylation reaction. Reproduced 263 235 1 29' L 100 200 m/z 300 TBT Fig. 10 Mass spectrum of (C4H9)3SnC2H5. Reproduced with permis- sion from ref. 27. DBT MBT 4 IMT i- 100 h 8 - a, c 0 5 50 n a, .- L - a a !55 I I 197 1 227 L 0 0 2 4 6 8 Retention timdmin Fig. 13 Typical chromatogram of organotin standards. Concentra- tions were DMT 40, DBT 40 and TBT 60 ng 1-I as Sn.Reproduced with permission from ref. 28. 100 200 m/z 300 Fig. 11 sion from ref. 27. Mass spectrum Of C6H5Sn(C&)3. Reproduced with permis-Analyst, July 1994, Vol. 119 1435 overcome by Blais and Marshall17 by utilizing post-column derivatization of the ionic alkylleads after they had been separated by high-performance liquid chromatography (HPLC). This separation on a CIS column was effected on the tetramethylenedithiocarbamate complexes, which after elu- tion were derivatized with STEB (Fig. 3). Blais and Marshall17 reiterated reactions (7), (13) and (14) and although they carried out an optimization of their system by a 25 factorial, they found optimum STEB concentration and H2 flow rate for the quartz furnace similar to those established in ref. 11.The post-column reaction assembly (Fig. 4) under optimum conditions assisted in achieving concentration detection limits similar to those with the GC-AAS system when the precon- centration steps were carried out prior to injection into the HPLC system. As an alternative to AAS or GC-AAS, it is possible to analyse water for Pb2+ by gas chromatography-mass spec- trometry (GC-MS). Feldman et a1.18 spiked tap water with 206Pb, derivatized it with STEB, extracted the (C2H5)4Pb derivative with heptane and analysed the sample by GC-MS with single-ion monitoring (SIM). The 206Pb acts as an internal standard and also as a marker for isotopic monitoring. In the SIM mode the mass spectrometer is focused at the mlz 293 ion [(C2H5)3206Pb+] and the mlz 295 ion [C2H5)3208Pb+]. The derivatization yields suffer from interference from Fe, Zn and Cu ions (Table 4) and the detection limit is worse than those obtained in previous work"+,15 owing to the large variability of the blanks.However, the GC-MS method succeeds in separating tetramethyllead from other interfering metal compounds, hence avoiding the use of high-resolution MS to identify the Pb isotopes. Sediment (1 .O g) in polycarbonate (methanolic HCI) or glass (methanolic NaOH) bottle f Add methanolic HCI or methanolic NaOH Procedure 1 Procedure 2 Procedure 3 (Methanolic NaOH) (Methanolic HCI) (Methanolic HCI) 1 1 1 Centrifuge 20 min with 2.0 mol I-' NaOAc 1 1 and adjust pH to 4.1 acetic acid, then store in a 30 ml adjust pH to 4.1 20 min at 4000 20 min at 40009 Analysis using in situ ethylation, cryogenic < trapping and GC-AAS Separate supernatant and store in a 30 ml polycarbonate bottle Fig.14 Extraction procedures of butyltin compounds from sediment with methanolic HCl and methanolic NaOH. Mercury and Methylmercury The potential of STEB to derivatize ionic mercury compounds was clearly indicated in the work of Honeycutt and Riddleg-10 and further demonstrated by Rapsomanikis et al.11 Although at the time that study was carried out it was not one of the aims, the derivatization reaction for CH3Hg+ was tried in a sediment matrix using GC with flame-ionization detection (FID) (Fig. 2). Buffer was not added, nor was any attempt made to optimize the conditions for the derivatization of Hg2+ or CH3Hg+ added to the sediment sample.Bloom'9 published an extensive study of the application of the derivatization method to environmental samples contain- ing Hg2+ and CH3Hg+. In Bloom's work, optimized reaction conditions confirmed the initial findings described in ref. 11. For example, the most efficient pH for the ethyl transfer was found to be between 4.5 and 7. Reaction times and the NaBEt, concentration in the reaction solution were also optimized (Fig. 5 ) . It was unfortunate that the one at a time approach was used for this optimization, which if it was performed correctly would have required 54 experiments (625 experiments for five values of each of the four variables)? In contrast, the simplex optimization method in ref. 11 required only 15 experiments. Although the experimental atomic fluorescence spectrometric (AFS) set-up is not shown, it was later made commercially available.However, one should be cautious about its quoted sensitivity, considering the interme- diate second-stage adsorption and desorption steps and the thermal destruction prior to detection (revised sensitivity figures are quoted in ref. 21). However, Bloom19 demon- strated that the speciation of environmentally important mercury and organomercury compounds is possible, although with difficulty in high CI--containing matrices. A number of fish tissue samples (spiked and unspiked) were analysed for methylmercury and labile mercury. Water and sediment spiked and unspiked samples were also analysed. The recoveries from all spiked samples whether high in C1-content or not approached loo%, within experimental error. In general, the methods described by Bloom demonstrate the suitability of the ethylation derivatization method for the speciation of mercury in environmental samples."11 c 1 2 3 4 Ti me/m i n Fig. 15 Chromatogram of a mixed organotin standard: A, Me3SnEt (2.5 ng); B, Me2SnEt2 (2.6 ng); C, MeSnEt3 (3.8 ng); D, Et&; E, BuSnEt3 (2.6 ng); F, Bu2SnEt2 (2.4 ng); and G, Bu3SnEt (7.6 ng).1436 Analyst, July 1994, Vol. 119 Once it had been demonstrated that the ethylation of methylmercury using STEB is feasible in aqueous sedi- ments," its application to the analyses of fish samples was carried out by Rapsomanikis and Craig.22 In a round-robin inter-calibration exercise, liquid samples were distributed by the BCR (Community Bureau of Reference of the EEC).It was unfortunate that the fish tissue had already been extracted with toluene solution using the cumbersome and outdated technique of the 1960s.23 We had to back-extract the methylmercury from the toluene solution into an aqueous solution. The aqueous methylmercury solution forwarded as a standard was analysed directly by ethylating it with STEB. A measured volume of aqueous standard or sample was added to 1 ml of 1% STEB solution in ethanol, reacted for 15 min and then analysed. The apparatus used consisted of a conventional gas chromatograph coupled with an atomic absorption spec- trometer fitted with an electrically heated quartz furnace atomizer (Fig. 6). The detection system was optimized for the mercury derivatives by varying, one at a time, the flow rates of nitrogen, oxygen and hydrogen gases and the furnace temperature.The detection limit of this method (167 pg of CH3HgCI or 133 pg of Hg as CH3HgCI) was adequate for the determination of methylmercury in the fish tissue and each chromatographic determination was carried out within 5 min (Fig. 7). The relative standard deviation of the above 100 ml tap water 10 ml buffer of NaOAc-HOAc 1 inject 3 ml NaBH, solution into reactor, I add 130 pl of NaBEt, solution, then react for 14 min 1 purge 9 min with He onto the cold trap (-1 96 "C) remove liquid N,, then elute species by heating the cold trap from -1 96 "C to +200 "C Detection by AAS, quantification by peak area I . and retention time Fig. 16 Flow diagram to show the procedures for the determination of butyltin species using (1) hydride generation and (2) ethylation derivatization techniques.measurements varied between 2 and 6% and the results agreed very well with the mean value obtained in measure- ments in eight other laboratories. It was then considered appropriate to analyse fish tissue directly in aqueous media as the ethylation derivatization reaction can take place in aqueous solutions. To demonstrate the accuracy of the method, standard reference fish tissue materials were purchased from the National Research Council of Canada and their methylmercury content was determined by Fischer et al.24 The tissue was simply dissolved in 10 ml of L I I I I I 1 2 3 4 E F 1 2 3 4 Time/min Fig. 17 Chromatograms for analysis of spiked River Main sediment using (a) hydride generation and ( b ) ethylation: A, BuSnEt,; B, Bu2SnEt2; C, Bu3SnEt, D, BuSnH3; E, Bu2SnH2; and F, Bu3SnH. Reproduced with permission from ref.31. Table 6 Detection limits of butyltin species in sediment Hydride generation Ethylation Ethylation Species "g ng g-I Sn (dry mass)* ng ng g- Sn (dry mass)+ ng ng g- Sn (dry mass)$ BuSn3+ 0.03 6.0 0.07 9 0.07 0.20 B u2Sn* + 0.03 6.0 0.34 38 0.34 0.10 Bu3Sn+ 0.15 33 0.11 12 0.11 0.44 * 45 ml of extraction solvent, 0.2 ml of which was analysed. + 45 ml of extraction solvent, 0.4 ml of which was analysed. * 45 ml of extraction solvent, 16 ml of which plus 0.8 ml of NaBEt4 solution were added to the reaction vessel.Analyst, July 1994, Vol. 119 1437 25% methanolic KOH, the solution was diluted to 20 ml with methanol and a measured volume of the extract was analysed using GC-AAS.The experimental set-up was similar to but simpler than that originally employed for the organolead analysis described in ref. 11. No water trap was used and no gases were added to aid atomization. The detection limit was improved 30-fold to 4 pg of Hg as CH3Hg+ owing to the shorter transfer lines and the use of an electrodeless discharge lamp. Concentration detection limits could have been improved if amounts larger than 250 p1 of extract were analysed. Optimum values of the important parameters for the determination of methylmercury using this experimental set-up were found to agree with our previous findings.” All mercury species in the tissue were identified but they were not determined as this was not one of our original goals (Fig.8). The standard additions method was used, to take into account matrix interferences during analysis. Weighed standard addi- tions calibration graphs were only necessary for the determi- nation of methylmercury in reference material DOLT-1 (dogfish liver). The results agreed well with the certified values and the relative standard deviation of the technique varied between 6 and 8% except for the DOLT-1 sample, for which it was 16% (Table 5 ) . Tin and Organotin Compounds Clearly, the ethylation derivatization chemistry, the C2Hs- transfer, can take place in aqueous solutions and to a number of metals. An obvious candidate for the derivatization by ethylation was tin and other hydride-forming metals and metalloids.In a preliminary study this was tried by Ashby et a1.25 qualitatively for the determination of organotins in a GC-AAS set-up which had the pre-column impregnated with STEB. The system was successful for the ethylation only of SnCI2, (CH3),lSnC14_, (n = 1-3), Et2SnC12, Pr3SnCl and Bu3SnC1. No reaction yields or conditions were given and the work has not been followed by an extensive analytical report. The reasons for the failure of the experimental set-up to determine other organotin species were not discussed. A different approach was attempted for the determination of butyltins in British estuaries by Ashby and Craig.26 To the dry sediment, 20 ml of distilled water, an internal standard and 5 ml of concentrated HCI were added.The mixture was left overnight and then extracted with 10 ml of a solution of dichloromethane containing 0.05% of tropolone. After filtra- tion, excess of tropolone was destroyed with iron(l1) sulfate and the organic layer was separated and evaporated lo dryness with a gentle stream of nitrogen. The residue was dissolved in about 0.5 ml of ethanol and one drop of 1% m/v STEB solution was added for derivatization. The solution was left for 10 min prior to injecting about 5 pl into the GC-AAS set-up. The method is not simple to carry out and the analytical precision, reproducibility and accuracy may be questionable. Also, the shape of the chromatographic peaks makes accurate quantification difficult. Further, it is clearly unnecessary to use the ethylation method for the determination of butyltins as the dried extract could be subjected to Grignard derivatization.The derivatization by ethylation was initially conceived because it can take place in aqueous media. Similar methodology was employed by the same group to demonstrate the ethylation of a larger number of organotin compounds. As aqueous standards not only the methyl-, ethyl- and butyltins mentioned in ref. 25 could be ethylated but also the whole range of butyl-, phenyl- and cyclohexyl- tins.” Most of the ethylation reactions were carried out in ethanol, so that injection into the GC-AAS or GC-MS systems could be effected without solvent extraction. The identity of the ethylated compounds was confirmed by GC- MS but environmental samples were not analysed (Figs. 9- ll).*7 Also in the same study an attempt was made to ethylate methyl-, butyl-, phenyl- and cyclohexyltin compounds on the pre-column of the GC-AAS apparatus, but with limited success.The ethylation procedure was also employed to determine ng 1-1 concentrations of butyltins in sea-water by Michael and Averty.28 The sample (250 ml) was simultaneously extracted and ethylated in isooctane solution that was present in the narrow neck of a specially designed bottle (Fig. 12). The isooctane solution with the butylethyl compounds was ana- lysed by GC with flame-photometric detection (Fig. 13). The optimum reaction time and pH were similar to the values quoted in ref. 11. Although the detection limit is approxi- mately 0.5 ng I - l , it is difficult to accept statements such as ‘linearity range of 0-200 ng 1-l’ or ‘range found in natural water (O-lOOO ng I-l).’ Quantitative yields of ethylation are obtained with this methodology as the slopes of the calibration graphs for ethyl derivatives are bracketed by slopes of the calibration graphs for pure tetraethyl- and tetrabutyltin.Cai et al.29 applied the method of derivatization by STEB directly to sediment aqueous extracts in a simple purge and trapAAS system. In the absence of standard reference material for butyltins in sediment, a river sediment sample containing low or undetectable amounts of butyltin com- pounds was spiked and equilibrated with known amounts of these compounds. It was then analysed using a ‘variable volume extraction method’ (VVEM) to determine the true concentration of these compounds in the sediment and according to procedure 3 in Fig.14. The ‘in situ’ ethylation derivatization procedure was optimized using simplex optimi- zation.15 Briefly, 10 ml of acetate buffer (pH 4.1) and a stirrer bar were placed in the reaction vessel, then a certain volume of the extract and STEB (130 pl) were added. The reaction vessel was closed and secured and the solution was stirred for 14 min. It was then purged for 9 min with helium so that the ethyl derivatives were swept into a chromatographic column immersed in liquid nitrogen. Controlled heating of the column resulted in separation and determination of all the butyl and methyl derivatives (Fig. 15). It was found that colloidal material appearing in the extract after the adjustment of the pH to 4.1 impeded the derivatization yields.This interference was bypassed by adjusting the pH prior to centrifuging, a procedure that did not interfere with the determination of the butyltin compounds. After elemental analysis it was estab- lished that the colloidal material contained large concentra- tions of Fe, P, Al and Ca. Further work to establish the molecular composition of these colloids is required, however. kB H 60 s Time .--, Fig. 18 (A) Typical traces for Cd obtained under the conditions reported in ref. 33, 1 ml sample volume; and (B) baseline noise X 20. Reproduced with permission from ref. 33.1438 Analyst, July 1994, Vol. 11 9 Detection limits were in the range of a few nanograms of tin per gram of dry sediment and depended on the volume analysed.In view of the interferences encountered using the hydride generation method for the determination of butyltins in sediments by Desauziers et aZ.,30 Cai et. aZ.31 compared the hydride generation and the ethylation derivatization methods on the same sample. An optimized extraction procedure, developed by the same group,32 was followed and the extract was analysed with the same apparatus using both methods shown in Fig. 16. The ethylation derivatization method had a better detection limit because no foaming or high pressure build-up occurred during the reaction, no cleaning of the extract was necessary and hence a larger volume could be analysed (Table 6). The absolute detection limits of both methods were comparable. However, the ethylation derivati- zation method requires a longer reaction and purge time in the reactor than the hydride generation method, 23 min compared with 4 min.The chromatographic elution times were compar- able (Fig. 17). The low detection limits coupled with the simplicity of the procedure, however, may give the advantage to the ethylation procedure, if it proves to be interference free for a number of different sediment samples. Cadmium Inorganic cadmium aqueous standards were analysed by D'Ulivo and Chen33, using derivatization of cadmium with STEB. It is assumed that the derivative compound is (CzH5)ZCd but the identity of the derivative product has never been confirmed. The aqueous standards are derivatized in a reaction vessel resembling a hydride generation vessel and the derivatized products are immediately and continuously fed through to the atomizer. They demonstrated that the optimum derivatization pH is >2.5 and that the flow rate of the sweeping argon gas should be high enough (optimum 1.2 1 min-I) to sweep the derivative cadmium product to the atomizer before it decomposes. Very high flows of argon resulted in imprecise measurements.A non-dispersive atomic fluorescence spectrometric (NDAFS) detection optical set-up with a miniature hydrogen-argon flame atomizer or an air- acetylene flame-heated silica tube were used for the detection of Cd. The signal had a rise time of approximately 30 s (Fig. 18) and the detection limits were 0.2 and 1 ng ml-' for the NDAFS system and AAS system, respectively. Interferences to the analytical signal from a number of metallic compounds were also determined (Table 7).Recoveries of Cd-spiked samples of tap and sea-water were virtually quantitative (90- 96 k 4%). In a similar excercise the derivatization vessel was connected to an inductively coupled plasma atomizer.34 Detection limits similar to those with the AAS and NDAFS Table 7 Interference from some foreign elements and compounds Element or Concentration/ Cadmium/ Signal compound pg ml-1 ng ml-I depression 3 x 10" 10 10 10 10 10 10 10 10 1 1 x 103 10 0 10 0 10 0 10 0 10 0 10 0 10 50 10 47 10 52 10 98 0.35 (blank) ND* systems were obtained but severe memory effects occurred with the experimental set-up used. Other Metals STEB has been investigated for its capability to transfer an ethyl group to the Rh metal centre of the Rh-triphos complex by Thaler and Caulton,35 in CD2C12 solvent. They deduced the mechanism of ethyl transfer and established that an Et- group directly transfers to the metal centre (Fig.19). Although this study had little analytical significance, it confirmed experi- mentally the Et- transfer mechanism and pointed to the fact that STEB can transfer Et- to a number of metal centres provided that the product is stable enough to be identified. It has also been shown by Ashby et al.25 that STEB can transfer Et- to (CH3)3Ge+ presumably to form (CH3)3Ge(C2H5) and to NazSe, Se02, Na2Se03 and Na2Se04 in all instances to form (C2H5)2Se. However, no yields, no spectra and no reaction conditions were discussed. Also, no explanation was given for the sole (C2H5)2Se product of the reactions of STEB with Se compounds of different oxidation states. It is noteworthy that D'Ulivo and Chen33 found that STEB reacts with TI to produce ethyl derivatives of unknown composition.Experimental conditions were not described but it was found that the T1 derivatives did not produce a linear response with concentration, at least when an NDAFS detector was used. Conclusion Alkyl transfer to a metal centre in aqueous solutions was the aim of the initial work with alkylboronic acids and trialkyl- I phydrogen CH,CH,Bet, migration -Bet, (trip hos) R hC,H,' I I P-hydrogen H migration H 3 Fig. 19 Ethyl anion transfer to 1 from STEB proceeds via inter- mediate 2 and pathway C to product 3, RhH(C2H4)(triphosphate). * No signal was detected.Analyst, July 1994, Vol.119 1439 borates, but the yields were not always quantitative. Honey- cutt and Riddle intended to use the process commercially for the preparation of automobile fuel alkyllead antiknock compounds. We were the first to use STEB as a derivatizing reagent and as an alternative to the hydride generation derivatization reaction. In situ ethylation of ionic lead, methyllead, methyl- mercury and mercury compounds was demonstrated as a viable analytical tool in 1986.11 A number of publications on the determination of Pb and Hg compounds were subse- quently published. It has been proved that for Sn, ethylation using STEB may be preferable to hydride generation because it does not suffer from critical interferences, or at least these can be masked simply.Foaming does not occur during the derivatization of environmental samples containing butyltin compounds, whereas this occurs with the hydride derivatization procedure. The ethyl derivatives of alkyltins appear to be more thermally stable than hydride alkyltin derivatives, once formed. These observations are based on precision measurements during comparison of the two techniques and are not in conflict with thermodynamic data for ethyl-tin and hydrogen-tin bond energies. We have also demonstrated using Canadian Standard Reference fish materials and laboratory-made apparatus based on AAS that one can determine all mercury species in the sample by a simple dissolution step and ethylation with STEB. All extraction and back-extraction steps can be avoided, hence the analysis time and precision should improve dramatically.It is hoped that because of its simplicity, ethylation will become the method of choice for the speciation of Hg in environmental samples. Cadmium has also been determined using STEB as a derivatization reagent and NDAFS. One assumes that the unstable derivative species is (C2H5)2Cd, and (C2H5)3T1 in the case of TI. The mechanism of ethyl anion transfer to the metal centre has been confirmed by utilizing a Rh complex in CD2C12 solvent. It is also promising that a number of other metals and organometallics such as Ge and Se can be determined by ethylation using STEB, but not without problems, and that a number of researchers are working on perfecting these techniques. Thanks are due to the funding agencies that have funded our work using STEB as a derivatization agent, namely the US National Science Foundation (1983-85), British Council (1989), Max-Planck Society and Deutsche Forschungs- gemeinschaft (1990 to date).A colleague and friend, 0. Donard, whose initial disbelief in the aqueous ethylation process sparked the onset of this research endeavour is acknowledged. Many thanks are due to Y. Cai and R. Fischer, past and current colleagues, for their tireless research efforts. The help of C. Harris with the manuscript is also appreciated. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Michaelis, A., and Behrens, M., Chem. Ber., 1894, 27, 244. Khotinsky, E., and Melamed, M., Chem. Ber., 1909,42,3090.Ainley, A. D., and Challenger, F., J. Chern. SOC., 1930, 2171. Freidlina, R. C., Nesmeyanov. A. N.. and Kocheskov, K. A., Chem. Ber., 1935, 68, 565. Challenger, F., and Richards, 0. V., J. Chem. SOC., 1934,405. Snyder, H. R., Kuck, J. A., and Johnson, J. R., J. Am. Chem. SOC., 1938, 60, 105. Honeycutt, J. B. J., and Riddle, J. M., J. Am. Chem. SOC., 1959, 81,2593. Honeycutt, J. B. J., and Riddle, J. M., J. Am. Chem. SOC., 1960, 82, 3051. Honeycutt, J. B. J., and Riddle, J. M., J. Am. Chem. SOC., 1961, 83. 369. Rapsomanikis, S., Donard, 0. F. X., and Weber, J. H., Anal. Chem., 1986, 58, 35. Damico, R., J. Org. Chem., 1964, 29, 1971. Thompson, R. J., and Davis, J . C. J., Znorg. Chem., 1965, 4, 1464. Binger, P.. and Koester, R., Znorg. Synth., 1974, 15, 136. Anderson, M., Simplex Optimisation Program in C , University of New Hampshire, New Hampshire, USA, 1984. Sturgeon, R. E., Willie, S. N., and Berman, S. S., Anal. Chem., 1989, 61, 1867. Blais, J. S., and Marshall, W. D., J. Anal. At. Spectrom.. 1989, 4, 641. Feldman, B. J., Mogadeddi, H., and Osterloh, J. D., J. Chro- matogr., 1992, 594, 275. Bloom, N., Can. J. Fish. Aquat. Sci., 1989, 46, 1131. Miller, J. C., and Miller, J. N., Statistics for Analytical Chemistry, Ellis Horwood, Chichester, 1984, pp. 156-165. Lansens, P., Meuleman, C., Casais Laino, C., and Baeyens, W., Appl. Organomet. Chem., 1993, 7, 45. Rapsomanikis, S., and Craig, P. J., Anal. Chim. Acta, 1991, 248, 563. Westoo, G., Acta Chem. Scand., 1966, 20, 2131. Fischer, R.. Rapsomanikis, S., and Andreae, M. O., Anal. Chem., 1993,65, 763. Ashby, J. R., Clark, S.. and Craig, P. J., J. Anal. At. Spectrom., 1988,3, 735. Ashby, J. R., and Craig, P. J., Sci. Total Environ., 1989, 78. 219. Ashby, J. R., and Craig, P. J., Appl. Organornet. Chem., 1991, 5, 173. Michael, P., and Averty, B., Appl. Organomet. Chem.. 1991.5, 393. Cai, Y., Rapsomanikis, S., and Andreae, M. O., J. Anal. At. Spectrom.. 1993,8, 119. Desauziers, V., Leguille, F., Lavigne, R., Astruc. M., and Pinel, R., Appl. Organomet. Chem., 1989,3. 469. Cai, Y., Rapsomanikis, S., and Andreae, M. O., Anal. Chim. Acta, 1993,274,243. Cai, Y., Rapsomanikis, S., and Andreae, M. O., Mikrochim. Acta, 1992, 109, 67. D’Ulivo, A., and Chen, Y., J. Anal. At. Spectrom.. 1989,4,319. Manzoori, J. L., Tao, H., and Miyazaki, A., paper presented at the XXVII Colloquium Spectroscopicum Internationale, 1991, paper C-PO-2. Thaler, E. G., and Caulton, K. G., Organometallics, 1990. 9, 1871. References Michaelis, A., and Becker, P., Chem. Ber., 1882. 15, 180. 1 Paper 31046441 Received November 8, 1993 Accepted December 6, 1993

ISSN:0003-2654    

DOI:10.1039/AN9941901429

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, July 1994, Vol. 119 1441 Direct and Rapid Determination of Potassium in Standard Solid Glasses by Excimer Laser Ablation Plasma Atomic Emission Spectrometry* Yong I11 Lee Department of Chemistry, Keonyang University, Nonsan, Chungnam 320-800, South Korea Joseph Sneddont Department of Chemistry, McNeese State University, Lake Charles, L A 70609, USA A rapid, direct, and sensitive method for the determination of potassium in solid glasses based on excimer laser ablation atomic emission spectrometry (LA-AES) has been developed. This technique allows the direct detection of 0.13 pg g-1 of potassium in solid glass without sample preparation. Results show that the excimer LA-AES system can provide a precision of f10% or better, and a linear response up to at least 461 pg g-1.Keywords: Excimer laser ablation plasma atomic emission spectrometry; glasses; potassium Introduction As solids are widely used in industry, it is important to have rapid, accurate, and precise on-line methods for the analysis of trace elements. This has led to an interest in the development of new and improved analytical methods. Laser ablation, which produces a high density plasma, is receiving a lot of interest as an alternative to conventional plasma sources for the spectrochemical analysis of solid materials. Recent advances include more reliable and power- ful laser systems, which have initiated growth in the field of laser atomic spectrometry and transferred the power of laser spectroscopy from the research laboratory to the analyst's bench-top.Laser excitation sources are particularly useful for remote analysis, refractory materials, non-conductive solids, in-situ analysis of a point on a surface, and local analysis (i.e., minute sampling of a large sample). The current status and direction of work on laser atomic spectroscopy has been discussed in detail by Thiem et al.1.2 A comprehensive review of laser radiation with solid materials is also available; this includes over 1000 references. Laser-ablation plasmas"5 or laser sparks6 can be used either as atomization and excitation source or can be probed spectroscopically for the direct elemental analysis of the solid materials. Uebbing et al.7 succeeded in increasing the intensities of analyte lines by reheating a laser-produced plasma by a second pulse laser.They used an excimer laser (XeCI; wavelength, 308 nm) as atomizer and an Nd-YAG laser to reheat the plasma. KO et aZ.8 studied the conditions for internal standardization using binary samples (Fe-Cr and Zn- ' Presented, in part, at 31st Eastern Analytical Symposium (EAS), Somerset, NJ, USA, November 1620, 1992. t To whom correspondence should be addressed. Cu) and showed that internal standardization is possible with a sufficient time delay (At 3 16 ps, t = time). We9 have described the use of excimer laser-ablation atomic emission spectrometry (LA-AES) as a quantitative analytical method for determining chromium in standard low-alloy solid steel samples. Use of the excimer laser in analytical atomic spectroscopy is unique, as most work involving laser ablation has been based on solid-state lasers.The excimer laser has been widely used in industrial applications such as etching, cutting, and deposition methods. As a source of laser ablation plasma the excimer laser has a potential advantage over the solid-state laser. Most excimer lasers emit in the short wavelength ultraviolet region where the reflectivity of metals and, to a lesser extent, glasses is lower than at longer wavelengths, hence the absorptivity is higher. For example, the percentage of energy absorbed by copper is only 1% at 10.6 pm whereas at 0.25 pm (250 nm) it is 70%. The same is true for nickel and silver with approximate values of 5 and 1% , respectively, at 10.6 pm, and 58 and 77%, respectively, at 0.25 pm. In addition, ultraviolet photons are more energetic (4-6 eV) and can therefore interact non-thermally with molecular materials and may induce photochemical reactions.This efficient coupling of the laser energy to the solid sample should lead to an improved system. The disadvantage of the excimer laser is the perception that they are not as reliable as solid- state lasers. This was a valid criticism of early excimer laser designs. However, modern excimer lasers are used to produce laser radiation in the ultraviolet region both reliably and efficiently. The type of spectra emitted by the excimer laser ablation plasma and spectral resolution vary depending on the portion of the plasma after irradiation of the laser pulse. Emission from the inner-sphere plasma appears primarily as intense atomic lines, while emission from the outer sphere shows reversals of the ion and atom lines.Space-resolved studies of the excimer laser ablation plasma has been applied to the analysis of solids to maximize the line-to-background (WB) ratio of the analytical signal. The ideal emission signal for direct spectrochemical analysis was observed at the edge of the inner-sphere plasma; the 30 detection limit for chromium was 20 pg g- .9 The present work describes further developments, which focus mostly on the determination of trace amounts of potassium in standard glass samples using excimer LA-AES. Arrowsmithlo determined selected metals in glasses using laser ablation with an Nd-YAG laser and inductively coupled plasma mass spectrometry. The analytical performance characteristics (linearity, preci- sion, and detection limit) of excimer LA-AES for the determination of potassium in solid glasses are presented.1442 Analyst, July 1994, Vol.119 Experimental A schematic diagram of the experimental set-up is shown in Fig. 1. The details of the system have been described previously.4.5 A pulsed ArF excimer laser (Questek, Billerica, MA, USA) operated at 193 nm was used to ablate solid glass samples to provide a vapour plasma above the sample surface. The solid samples were placed in an enclosed laboratory-made chamber which enabled the surrounding atmosphere and pressure to be controlled.4.5 The operating conditions for the excimer LA-AES system are given in Table 1. The excimer Fig. 1 AES system. Schematic diagram of the experimental set-up for the LA- Table 1 Experimental set-up and typical operating conditions for the excimer LA-AES system Laser system- ArF excimer laser energy per pulse 150 mJ at 193 nm Laser pulse width (FWHM) 10 ns Spectral linewidth 0.4 nm Repetition rate 2 Hz Ablation chamber- Material Internal diameter Window Monochromator- Type Grating Throughput Entrance slit T-type stainless steel 69.85mm 2.0 mm thick, fused silica Czerny-Turner design, Ebert configuration 1200 lines mm- Focal length 3.7 50 pm wide x 5 mm high Detector (photodiode array)- Array size 512 elements Spectral response 180-1100 nm Dark current Typically 0.5 pA (50 pm x 2.5 mm) Integration time 60s beam was focused onto the sample surface by two fused silica lenses; an optimum spot size of 1.12 mm2 provided a power density of 1.02 x 109 W cm-2.The optimum spot size depends on the sample material. Three glass-matrix standard samples from the National Institute of Standards and Technology (NIST) (Gaithersberg, MD, USA), NIST 610,612, and 614 from the 610 series, were ablated with the excimer laser beam without chemical sample pre-treatment. The stainless-steel sampling chamber was evacuated several times by a roughing pump and filled with helium gas (99.997%) to obtain the maximum L/B ratio.5 The inert helium gas was used as a buffer gas to prevent rapid oxidation of the free sample atoms in the plasma. The emission lines were monitored using a photodioide array system (Oriel, Stratford, CT, USA) and were integrated within 1 s of exposure. The spectra shown in this paper are the averages of 16 spectra taken for each sample. Results and Discussion Direct observation of the excimer laser ablation plasma using atomic emission spectrometry is a simple method for the analysis of sample surfaces and offers the potential of simultaneous multielement analysis. It is possible to perform simultaneous qualitative analysis by examining the wave- lengths in the emission spectrum of an unknown, because the energy levels are unique for each element.Proper selection of spectral lines provides reasonable multielemental analytical capabilities. The shape of the excimer laser ablation plasmas under a helium atmosphere at 101 kPa was observed photographically for a target surface of a standard glass sample. A description of the technique of photographing the plasma is described elsewhere.5 The single laser shot image of the plasma is shown in Fig.2. The plasma was rose to approximately 16 mm in height above the solid surface and was approximately 18 mm in diameter. Fig. 3 shows the emission spectra obtained for the excimer laser ablation plasmas formed with three glass-matrix samples over the spectral range 660-780 nm. The spectra were detected at 0.6 mm from the sample surface. Very low background emission was observed under a helium atmosphere. The major lines were attributed to the glass matrix (72% SO2, 12% CaO, and 14% Na20). Each spectra displays complex interferences and overlaps because the matrices of the glass samples incorporated many elemental components. Fig. 3 shows calcium atomic [Ca(I)] lines at 671.87, 715.03, 720.87, and 733.1 nm arising from the glass matrix.Two characteristic atomic lines of potassium [K(I)] are observed at 764.6 nm (766.4 nmll) and 768.0 nm (769.8 nmll). An intense, Fig. 2 Photograph of the singlc-shot excimer laser ablation plasma emission formed with glass under a helium atmosphere at 101 kPa.Analyst, July 1994, Vol. 119 1443 interference-free rubidium peak [Rb(I)] is also seen at 778.1 nm (780.0 nm).ll Calibration Graph The three standard glass samples were used to establish the calibration graph for K(1) (764.6 nm) shown in Fig. 4. This is a plot of the logarithm of signal intensity versus the logarithm of the NIST-certified concentration for potassium in the glass matrix. The mass concentrations of potassium in the three glass samples were as follows: NIST 610, 461 yg g-l; NIST 612,64 pg g-l; and NIST 614,30 k 1 pg 8-l.Each data point was obtained by subtracting the average background from the line intensity. The intensity was measured by integrating the peak area emission signals with the average of two determi- nations presented here. The constructed graph is a linear regression fit to the three concentration points, with a slope of 0.573 and a correlation coefficient of 1.00. Precision The precision of a calibration can be defined in terms of its relative standard deviation (sr), i.e., the ratio of the standard deviation to the mean of each set of measurements, expressed as a percentage. The standard deviation was calculated for three consecutive measurements of the emission from the L 200 counts I / 660 680 700 720 740 760 780 Wavelengthhn Fig.3 Excimer LA-AES spectra of glass-matrix standards (NIST 610 series) obtained using a single laser shot and a laser energy of 150 mJ pulse-'. Standard: (a) NIST 610; (b) NIST 612; and ( c ) NIST 614; asterisk indicates the wavelength (764.6 nm) that was used for quantification of potassium. 2.6 y = 1.0254 + 0.57333~~' = 1.000 In 1.8 I I I I I I 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 - 2.4 8 In Log concentration (ug g-') Fig. 4 Calibration graph for potassium in a glass-matrix system constructed from the 764.6 nm atomic lines shown in Fig. 3. r = correlation coefficient. laser ablation plasma from three glass samples; the 764.6 nm potassium line was used. The s, values for the potassium signals were 8.6% for NIST 610, 9.8% for NIST 612, and 10.2% for NIST 614.These figures are not statistically significant. When the concentration of potassium was increased to 461 pg g-l in the sample, the s, value for each signal decreased. This standard deviation could partly be a result of fluctuations in the power of the excimer laser. The pulse-to-pulse stability of the laser energy was k5'%0. A further contributing factor to the precision is the potential inho- mogeneity, typically +5%, of the standard solid glass samples. These factors could account for the decrease in analytical precision [compared with the precision for a solution sample (1-5%) obtained with a conventional atomic spectrometric method] observed for the excimer LA-AES system. However, a precision of _+ 10% is acceptable for an analytical method for solids requiring no prior sample pre-treatment. Detection Limit The detection limit (DL) of an analytical technique indicates the smallest detectable concentration that can be reported with a specified level of confidence as being present in a sample.Most commonly, the DL can be calculated directly from DL = ksbk/m, where k is the confidence factor, Sbk is the standard deviation of the blank measurement, and m is the calibration slope.12 The factor k is most often chosen to be 2 or 3. In emission spectrometry, the convention is to use k = 3; hence this value was adopted in the present work. The background was determined for the average value of intensi- ties at 763.9 nm and at 765.3 nm for the K(1) line.The calculated DL for potassium in solid glass was 0.13 pg g-'. This is comparable to other laser ablation systems. Conclusion This work constitutes an investigation of excimer laser ablation plasma atomic emission spectrometry. The primary advantages of this method are that it can be used for the direct determination of elements in solids, and can be applied, when speed is more important than accuracy, to on-line analysis. It can be used to analyse metals, in plants, to investigate and classify geological materials and chemical products, and to control product quality, etc. 1 2 3 4 5 6 7 8 9 10 11 12 References Thiem, T. L., Lee, Y. I., and Sneddon, J., Microchem. I . , 1992, 45, 1. Thiem, T. L., Lee, Y. I . , and Sneddon, J., Trends Anal. Chem., 1993, 12, 18. Darke, S. A., and Tyson, J. F., J. Anal. At. Spectrom., 1993,8, 145. Lee, Y. I., Sawan, S. P., Thiem, T. L., Teng, Y. Y., and Sneddon, J., Appl. Spectrosc., 1992,46,435. Lee, Y . I., Thiem, T. L., Kim, G. H., Teng, Y. Y., and Sneddon, J., Appl. Spectrosc., 1992, 46, 1597. Cremers, D. A., and Radziemski, L. J., Appl. Spectrosc., 1985, 39, 57. Uebbing. J., Brust, J., Sdorra, W., Leis, F., and Niemax, K., Appl. Spectrosc., 1991,45, 1419. KO, J. B., Sdorra, W., and Niemax, K., Fresenius' 2. Anal. Chem.. 1989,335, 648. Lee, Y. I.. and Sneddon, J., Spectrosc. Lett., 1992.25, 881. Arrowsmith, P., Anal. Chem., 1987, 59, 1437. Robinson, J. W., Practical Handbook of Spectroscopy, CRC Press, Boca Raton, FL, 1991. Ingle, J. D.. Jr.. and Crouch, S. R., Spectrochemical Analysis, Prentice-Hall, Englewood Cliffs, NJ, 1988. Paper 31055090 Received September 14, 1993 Accepted December 30, 1993

ISSN:0003-2654    

DOI:10.1039/AN9941901441

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, July 1994, Vol. 119 1445 Synthesis and Efficiency of a Polyacrylacylisothiourea Chelating Fibre for the Preconcentration and Separation of Trace Amounts of Gold, Palladium and Ruthenium From Solution Samples Xijun Chang, Zhixing Su, Guangyao Zhan, Xingyin Luo and Wenyun Gao Department of Chemistry, Lanzhou University, Lanzhou 730000, China A polyacrylacylisothiourea chelating fibre was synthesized using polyacrylonitrile fibre as a starting material, and the structure of the chelating fibre was determined by infrared spectrometry. The parameters influencing the efficiency of the fibre at concentrating trace amounts of Aum, Pdw, and Ru'", including acidity, flow rate, adsorption capacity, effect of re-use, interfering ions, and desorption, were investigated. Gold(m), Pdw, and Run' were enriched and separated from real samples and were detected using inductively coupled plasma optical emission spectrometry with satisfactory results.For concentrations of Aum, Pdw, and Run' of 0.008 mg 1-1, the relative standard deviation was 1.8% for Aum, 2.5% for Pdw, and 0.8% for Rum. The concentrations obtained for these ions in real solution samples by this method were basically in agreement with the given values, with average errors of less than 2.5%. The method is rapid, precise, simple, and convenient to use. Keywords: Polyacrylacy lisothiourea chelating Jibre; synthesis; preconcentration; gold; palladium; ruthenium; inductively coupled plasma optical emission spectrometry Introduction There are many examples of the determinations with precon- centration from sample solutions of trace amounts of noble metals by means of macroporous resins; these have a large adsorption capacity towards noble metals.1-14 However, in all these studies, the flow rates of the enriched elements were slow, because of the long soaking time used. A polyacrylamide oxime-carboxylic acid chelating fibre synthesized from poly- acrylonitrile fibre15 has been used to concentrate many elements, including the noble metals, from different sam- ples,16-2* rapidly and conveniently. However, when the fibre was treated with a strong acid and then eluted with a large volume of water, the fibre was found to swell; this resulted in problems with re-usage. The synthesis of acylisothiourea from a nitrile group compound or carboxylic ester as starting material23324 has been reported; however, the chelating functional groups were not grafted to any synthesized fibre, and the synthetic product was not applied to the enrichment and separation of trace amounts of elements.This paper describes the synthesis of a poly- acrylacylisothiourea chelating fibre and its structure, as determined by infrared (IR) spectrometry. The efficiency of the chelating fibre at preconcentrating and separating trace amounts of Au"', Pd'", and Ru1I1 from solution samples, as measured by inductively coupled plasma optical emission spectrometry (ICP-OES), is studied in detail. The experi- ments show that the chelating fibre exhibits more rapid adsorption and desorption velocities for trace amounts of Au"', Pd'", and Ru"' than the macroporous resin described earlier ,1-14 and possesses stronger acid resistance than ami- doxime-carboxylic acid fibre.15-22 The proposed method has the advantages of a faster adsorption rate, higher selectivity, more convenient operation, better precision, and lower detection limit (DL) than some existing methods. Experimental Synthesis of the Chelating Fibre A 2 g amount of dried polyacrylonitrile fibre, 40 ml of ethane- 1,2-diol, and 40 ml of NaOH (6 mol 1-l) were placed in a three-necked flask. The mixture was refluxed for 6 h at 60- 65°C with slow stirring, during which time 20 ml of H Z 0 2 (loo/) were added to the flask so as to speed up the reaction. After surplus H202 in the flask had been removed, the mixture was refluxed continuously for 12 h at 80-85°C with slow stirring, it was filtered, washed with distilled water until the pH of the washings was neutral, and dried by IR radiation.A 2 g amount of the dried polyacrylic acid fibre obtained and 80 ml of SOC12 were refluxed for 6 h at 6045 "C in the dried flask. Then the solution was filtered and the filtrate dried, before the product and 80 ml of CS(NH2)2 (20% solution) were dissolved with C5H5N and refluxed continuously for 6 h at 6045°C in the dried flask. A new polyacrylacylisothiourea chelating fibre was obtained on filtration, washing, and drying. The sulfur content in the chelating fibre was determined by the oxygen- flask method as 9.4%. Structure of the Chelating Fibre The IR spectrum of the polyacrylacylisothiourea chelating fibre is shown in Fig.1. According to reference spe~tra,243~5 6o 4 52 44 c 5 36 h 9) CI .- 28 s t- 20 I I l- I 4000 2666 1666 lo00 333 Wavenumberkm-' Fig. 1 Infrared spectrum of the polyacrylacylisothiourea chelating fibre.1446 Analyst, July 1994, Vol. 11 9 the peaks in Fig. 1 can be assigned as follows: v,,,/cm-l 3448.3 and 3319.5 (Y NH2 and Y NH), 2945.2 and 2874.9 (Y CH2 and Y CH), 1738.3 (Y C=O), 1685.1 (Y C=N), 1623.4 (as NH2 and 6 NH), 1457.0 (as CH2), 1250.3 and 1229.6 (6, CH2 and 6, CH2), 1171.7 (Y C-N and 6 O=C-S), 1074.0 (6 C-N and Y N=C-S), 964.8 (6 N=C-S), 833.0 (6 NH2 and 6, NH), 778.8 (6, NH and 6, CH2), 676.5 (Y C-S), 537.3 (6, C=O) and 2246.2 (there is 42% CkN remaining in the fibre) (where Y is a stretching vibration, 6, a bending vibration, 6s, a scissor vibration, 6,, a rocking vibration, 6,, a wagging vibration, and 6,, a twisting vibration).Clearly, this data confirms the existence of a C(=O)SC(=NH)NH2 group in the synthesized polyacrylacylisothiourea chelating fibre. Based on the above peak identities, and previously published work,23?24 the synthesis process can be briefly expressed as shown in Scheme 1. CH2COOH I NaOH + H202 -CH2CH-CH2CH-CH2C- > I I I HOCH2CH20H CN C-0 C-0 I I OCH3 OCH3 (93%) (5.7%) (1.3%) CH2COOH I -CH2CH-CH2CH-CH2C- I I I I I I c=o c=o c=o OH OH OH CHZCOCl SOCI;? I CS(NH2)2 --CH2CHCH2 CHCH2C- I I I C5H5N c=o C-0 c=o I I I c1 CI c1 0 NH II II CH2CSCNH2 I I I I -CH2CH-CH2CH-CH2C- C-0 c=o G O I I I II II II SCNH2 SCNH2 SCNH2 NH NH NH Scheme 1 Reagents Polyacrylonitrile fibre obtained from Lanzhou was cut using scissors, washed with distilled water and ethanol, and then dried under IR radiation.All reagents used were of analytical- reagent grade, unless specified otherwise, and distilled water was used throughout the procedure. Specpure HAuC14.4H20, (NH4)2PdC16, and (NH4)2R~(H20)C15 were purchased from Shanghai Reagent Factory. Stock solutions of Au"', Pd'", and Ru"' (1 g 1-l) were prepared by dissolving 0.2092 g of HAuCI4.4H20, 0.3338 g of (NH4)2PdC16 or 0.3288 g of (NH4)2Ru(H20)ClS, respectively, in 100 ml of HCI (1 moll-1). A mixed stock standard solution containing Ad1', PdIV, and Ru*I1, each at a concentration of 8 mg 1- l, was prepared by diluting 2 ml of each stock solution with 1 mol 1-1 HCI up to the mark in a 250 ml calibrated flask.Effect of Acidity on Adsorption A 1 ml volume of the mixed stock standard solution containing 8 mg 1- each of Au"', PdIV, and RulI1 was pipetted into beakers and diluted to 400 ml with distilled water. The solutions were adjusted to the desired pH in the range 1-6 with aqueous ammonia, and Au, Pd, and Ru ions in the solutions were concentrated in the adsorbing column loaded with the chelating fibre and desorbed with an eluent as described under Conditions for Desorption. The results of the determination, which are shown in Fig. 2, show that the recoveries of trace amounts of enriched Au, Pd, and Ru ions are greater than 98% at pH 4. However, the polyacrylonitrile fibre does not adsorb Au, Pd, Ru, and other ions at pH 4 because it does not contain the relevant analytical functional groups.Adsorption of Other Cations By following the described procedures, 20-200 pg I-1 of other cations in 400 ml solutions at pH 4 were passed through a fibre column and were detected by ICP-OES after the solution eluting from the column was concentrated to 10 ml. The results show that Ge4+, A$+, TP+, TI+, Ba2+, Ca2+, Mg2+, K+, and Na+ ions are not enriched by the fibre at pH 4, and I1.4+, Pt4+, Rh3+, Ni2+, Co2+, Fe3+, AP+, Mn2+, Pb2+, Sn4+, Ga3+ and In3+ are barely adsorbed (10-30%). Therefore, the enrichment of Au, Pd, and Ru ions at pH 4 does not suffer interference from these ions. Other ions, e.g., Cu2+, Zn2+, Cr3+, Cd2+, Hg2+, Be2+, and Bi3+ can be adsorbed by the fibre in the 5&70% range at pH 4; however, because the fibre adsorbs Au, Pd, and Ru ions strongly, their enrichment is not influenced by these other ions either.As for removing the other various cations from the fibre, I++ can be eluted with 10 ml of (1 + 1) KN02-NH4CI (10% solution), the elution conditions for Pt4+ and Rh3+ are similar to those for Au3+, Pd4+, and Ru3+, and the other cations can be desorbed from the fibre column with 10 ml of 1 4 moll-' HCI or HN03. These experiments show that the fibre offers higher selectivity for Au, Pd, and Ru adsorption than various existing resins614 or fibres.1622 Effect of Flow Rate on Adsorption Following the procedure described in the preceding section, the flow rates for the enrichment of Au, Pd, and Ru ions on the chelating fibre column were controlled to between 2 and 14 ml min-I.The results, which are given in Fig. 3, show that Au, Pd, and Ru ions can be concentrated quantitatively at flow rates less than 6 ml min-l. However, considering the 100 ' h 8 80 E a v C .O 60 -0 $ 4 0 . 20 0 1 2 3 4 5 6 PH Fig. 2 by the fibre column. Flow rate, 4-5 rnl min-'. Influence of pH on 0, Au, 0, Pd, and X , Ru ion adsorption1447 Analyst, July 1994, Vol. 11 9 complexity of the analysed samples (real samples containing interfering ions), a flow rate of 4-5 ml min-1 was selected for the concentration of Au, Pd, and Ru ions on the fibre column; recoveries of 98-100% were obtained. For the chelating resins described earlier,1-14 the flow rates of the noble metal ions adsorbed by these resins were usually below 2 ml min-1, which was clearly slower than the flow rate enriched in the experiment.Conditions for Desorption After the trace amounts of Au, Pd, and Ru ions had been enriched by the fibre as described in the preceding sections, the columns were eluted with diluted HC1, HN03 or CS(NH&, respectively. However, the recoveries of Au, Pd, and Ru ions eluted in this way were only 70430%. It was also observed that when the concentration of the eluent was greater than 5 mol 1-1 or the CS(NH2)2 content was greater than 2%, the results of the determination by ICP-OES were reduced by about lo%, because the nebulization rates for the eluates were different from those for the standard solutions. In order to achieve complete desorption of the analytes from the fibre column, the concentrations of the HC1 and CS(NH2)2 used and the desorption velocity were tested repeatedly for 10 ml volumes.The results, which are presented in Figs. 4-6, show that the Au, Pd, and Ru ions concentrated by the fibre - I 9 0 2 4 6 8 1 0 1 2 1 4 FIOW rate/ml rnin-' Fig. 3 Effect of flow rate on 0, Au, 0, Pd, and x , Ru ion adsorption by the fibre column. pH, 4 columns can be desorbed quantitatively with 10 ml of 3 4 moll-' HCl-1% CS(NH2)2 at a velocity of 2-3 ml min-l, with recoveries of 98-100%. In contrast, the reported velocities of elution of noble metal ions from resin columnsl-14 were usually less than 1 ml min-l, which was clearly slower than the elution rate of the experiment. Apparatus and Instruments A Model ICP/6500 inductively coupled plasma optical emis- sion spectrometer (Perkin-Elmer), a Model 170-sx Fourier transform IR spectrometer (Nicolet), and a Tiantsin Model pH s-73 digital pH meter (Shanghai Instrument Plant) were used in this study.A three-necked flask with a stirrer, a thermometer, and a spherical condenser pipe were used in the synthesis of the chelating fibre. The adsorbing column, 0.1 g of pure chelating fibre, was loaded in a glass tube (14 cm long, 0.4 cm i.d., 0.15 cm i.d. at the lower tapered end). Analytical Procedure The stock standard solutions of mixed ions or the real sample solutions with different matrix elements were prepared in cleaned vessels (200-1000 ml solutions). These solutions were adjusted to a pH of 4 with aqueous ammonia, and were passed through the adsorbing columns packed with the chelating fibre at a flow rate of 4-5 ml min-1.After eluting the analytes from the columns with 10 ml of 3-4 moll-' HCl-1% CS(NH& at a velocity of 2-3 ml min-1, trace amounts of Au, Pd, and Ru ions in the 10 ml of eluate were determined using the Model ICP/6500 spectrometer under the standard conditions listed in Table 1. Results and Discussion Effect of Interfering Ions The different interfering ions were added, separately, to the diluted mixed standard containing Au, Pd, and Ru ions, and VV 0 1 2 3 4 [HCl]/mol dm4 Fig. 4 Concentration of HCl for the desorption of 0, Au, a, Pd, and x , Ru ions from the fibre column [in 10 ml of 1% CS(NH2)2] 0 1 2 3 4 5 6 7 Elution velocity/ml min-' Fig. 6 Effect of elution velocity on 0, Au, 0, Pd, and X , Ru ion desorption from the fibre column [in 10 ml of 3-4 mol I-' HCI + 1% CS(NH2)21 0.2 0.4 0.6 0.8 1.0 [WNH,),] (W Fig.5 Concentration of C$(NH2)2 for the desorption of 0, Au, 0, Pd, and x , Ru ions from the fibre column (in 10 ml of 3-4 moll-' HCI) Table 1 Conditions for the detection of Au, Pd, and Ru using a Perkin- Elmer Model ICP/6500 spectrometer Parameter Value Forward power Ar plasma gas flow Ar auxiliary gas flow Wavelengths Viewing height Ar nebulizer gas flow Solution uptake rate Integration time 1100 w 14 1 min- 0.5 1 min-l Au, 242.795 nm Pd ,229.652 nm Ru, 240.272 nm 15 mm 1.01 min-' 1.0 ml min-l Au, 10s Pd, 10s Ru, 10 s1448 Analyst, July 1994, Vol. 119 were enriched and determined as described earlier. The results, given in Table 2, show that 400-fold excesses of Ca2+ and Mg2+, 200-fold excesses of Ni2+, Zn*+, Cu2+, AP+, and Fe3+, and a 100-fold excess of Co2+ ions caused little interference in the determination of Au"' and PdIV.The concentrations of ions providing no interference in the determination of Ru"' were reduced by half relative to the concentrations for the determinations of Au"' and PdIV. This is due to the lower adsorbing capacity of the chelating fibre for RulI1 if compared with the capacity for Au"' and PdIV ions. Various other concomitant precious and heavy metals (e.g., Pt, Ir, Rh, Os, Ag, Cd, Hg, Bi, and Tl) do not interfere with the analytes either because their concentrations in real samples are very low or the rates at which they are adsorbed by the fibre are much lower than the adsorption rates of the analytes.Analysis of Real Samples By following the described procedures, the accuracy of the proposed method was checked by analysing real solution samples obtained from two chemical plant using the standard additions method for calibration. Prior determination revealed that the samples contained about 5 mg 1-1 in total of Ni, Fe, and Co or of Cu, Zn, and Fe in the metal matrix. The results, which are listed in Table 3, show that the recoveries of the added Au, Pd, and Ru ions were in the range 96.6100%. In addition, the concentrations of Au, Pd, and Ru ions determined in the real samples by the proposed method were in basic agreement with the results obtained by the plants themselves using high-temperature electrothermal atomic absorption spectrometry, with average errors of less than 2.5%.Evidently, application of the proposed method to the described determinations is feasible and provides satisfactory results. Precision and DL of the Method Following the analytical procedures, eight portions of diluted mixed standard containing the equivalent of 8.0 pg 1-1 of Au, Pd or Ru in lo00 ml of solution were enriched and analysed simultaneously. The results are given in Table 4. These show that the average results for the eight determinations were 8.0 pg 1-1 for Au, 7.7 pg 1-1 for Pd, and 7.8 pg 1-1 for Ru. The relative standard deviations were 1.8% for Au, 2.5% for Pd, and 0.8% for Ru. If the concentrations of the analytes were lower than 8.0 pg I-l, the flow rate of the Au, Pd, and Ru ions for adsorption quantitatively by the fibre column had to be reduced to slower than 4 ml min-l.Clearly, the method offers better precision and a lower DL than some reported methods.622 Capacity of the Fibre Each diluted stock solution of 8.0 mg 1-l of Au, Pd or Ru was passed separately through the fibre column by following the above procedures. The Au, Pd or Ru eluting from the column was detected by ICP-OES until its initial concentration was achieved. The dynamic adsorption capacity of the chelating fibre was calculated to be 150 mg g-l for Au"', 100 mg g-l for PdIV, and 50 mg g-l for Ru"'. If the nitrile group in the chelating fibre could be transformed completely into the acylisothiourea group, the adsorbing capacity of the fibre for Au, Pd or Ru ions would have been relatively large. Table 2 Effect of interfering ions on Au, Pd, and Ru at a concentration of 0.020 mg 1-l Recovery (%) Interfering ion Ca*+ Mg2+ Ni*+ cu2+ Zn2+ A13+ Fe3+ co2+ Concentration*/ mg 1-1 8.0 (4.0) 8.0 (4.0) 4.0 (2.0) 4.0 (2.0) 4.0 (2.0) 4.0 (2.0) 4.0 (2.0) 2.0(1.0) Au 100 94.5 97.0 93.2 96.4 100 100 100 Pd Ru 99.0 96.0 93.4 92.5 92.5 94.5 95.3 96.2 98.0 95.4 97.0 96.0 100 96.5 94.5 92.5 * The value in parentheses is the concentration of the interfering ion providing the respective recovery of Ru.Performance of Re-used Fibre By following the proposed analytical procedures, after the trace amounts of Au, Pd and Ru ions enriched by the fibre have been desorbed quantitatively with 3 4 mol I-' HCI-l% CS(NH2)2 solutions, and the column has been washed with distilled water until neutrality is reached, the chelating fibre can be used repeatedly to concentrate trace amdunts of Au, Pd, and Ru ions.After 10 experiments, recoveries of greater than 94% were still achieved. In addition, even after being used 10 times, the chelating fibre did not display any obvious swelling effect. In contrast, the amidoxime-carboxylic acid fibre15-22 used previously swelled when it was re-used to enrich the determined ions. These results show that the chelating fibre has a better ability to be re-used and better stability than some existing fibres. ~~ ~ Table 3 Analytical results for real solution samples Concentratiodpg 1-1 Total concentratiodpg 1-l Added Recovery Sample* Given? Found Average pg I-' Found Average (%) 1- Au 15.0 15 .O 15.5 14.6 15.0 20.0 35 .O 35.2 34.7 35.0 100 Pd 16.0 16.1 16.2 16.2 16.2 20.0 35.5 35.8 36.0 35.8 98.0 Ru 8.0 8.0 7.7 8.3 8.0 20.0 27.2 26.7 27.8 27.2 96.0 Au 50.0 50.0 50.8 49.2 50.0 20.0 70.2 70.8 69.0 70.0 100 Pd 50.0 48.0 49.0 50.0 49.0 20.0 68.0 68.5 69.0 68.5 97.5 Ru 12.0 11.4 11.6 12.0 11.7 20.0 31.0 31.4 31.8 31.4 98.5 * Sample 1 was an aqueous liquid from a smelting plant, and sample 2 a diluted solution from a factory laboratory.Prior determination t The results obtained by the two plant laboratories using high-temperature electrothermal atomic absorption spectrometry. 2- indicated that each contained about 5 mg 1-l of metal in the matrix.1449 Analyst, July 1994, Vol. 119 ~~ Table 4 Analytical precision and DL for the proposed method Concentratiodpg 1-1 Recovery s, Element Added Found Average (YO) (Yo 1 Au 8.0 7.8 8.2 8.0 8.1 8.0 100 1.8 Pd 8.0 7.5 7.8 7.5 7.8 7.7 96.2 2.5 Ru 8.0 7.7 7.8 7.7 7.8 7.8 97.5 0.8 8.1 7.8 7.9 8.0 8.0 7.5 7.6 7.9 7.8 7.7 7.8 7.8 * s, = Relative standard deviation.Conclusion The polyacrylacylisothiourea chelating fibre can be syn- thesized readily and conveniently. It presents good stability and can be re-used efficiently. Preconcentration and separa- tion of trace amounts of AulI1, PdW, and Ru"' ions from some matrix elements can be carried out rapidly by using the chelating fibre and following a reliable column procedure, with satisfactory results. The proposed method is feasible and efficient for the determination of trace amounts of Au, Pd, and Ru ions in real solution samples. The method is also rapid, convenient, precise, and accurate.The authors thank Qun Zhao for his help with experimental work. References Myasoedova, G. V., Antokol, I. I., Bolshakova, L. I., Danilova, F. I., Fedotova, I. A., Varshl, E. B., Rakovskii, E. E., and Sawin, S. B., Zh. Anal. Khim., 1982.37, 1837. Siddhanta, S., and Das, H. R., Indian J. Chem., Sect. A , 1984, 23,937. Myasoedova, G. V., Antokol'skaya, I. I., and Sawin, S. B., Talanta, 1985,32, 1105. Siddhanta, S., and Das, H. R., Talanta, 1985,32,457. Kuz'min, N. M., and Krasil'shckick, V. Z., Zh. Anal. Khim., 1988,43, 1349. Lin, X., Zhen, W. Z., Hao, G. J., Yang, Y. Z., and He, B. L., Ion Exch. Adsorpt., 1986,2, 1. 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Wang, S. T., Chen, W. Z., and He, B. L., Chem. J. Chin. Univ., 1987,8, 81.Li, L. Y., Zhou, Y. Q., Yin, Z., and Wang, S. T., Fenxi Huaxue, 1987,15,297. Chang, X. J., Luo, X. Y., and Su, Z. X., Chem. J. Chin. Univ., 1988,9, 574. Chang, X. J., Su, Z. X., Zhan, G. Y., and Luo, X. Y., Chin. J. Chem., 1990,48, 157. Chang, X. J., Li, Y. F., Luo, X. Y., Zhan, G. Y., andSu, Z. X., Anal. Chim. Acta, 1991, 245, 13. Chang, X. J., Luo, X. Y., Zhan, G. Y., and Su, Z. X., Talanta, 1992,39,937. Su, Z. X., Chang, X. J., Xu, K. L., Luo, X. Y., and Zhan, G. Y., Anal. Chim. Acta, 1992, 268,323. Luo, X. Y., Su, Z. X., Zhan, G. Y., and Chang, X. J., Ion Exch. Adsorpt., 1992,8, 34. Su, Z. X., Luo, X. Y., and Chang, X. J., Hecheng Xianwei Gongye, 1984,6,22. Luo, X. Y., Chang, X. J., Su, Z. X., and Zhan, G. Y., Anal. Lab., 1984,5,52. Zhan, G. Y., Chang, X. J., Su, Z. X., and Luo, X. Y., Metallurg. Anal., 1985, 5 , 34. Chang, X. J., Zhan, G. Y., Su, Z. X., and Luo, X. Y., Fenxi Huaxue, 1986, 14, 1. Luo, X. Y., Chang, X. J., Su, Z. X., and Zhan, G. Y., Geol. Lab., 1986,2,218. Su, Z. X., Luo, X. Y., and Chang, X. J., J. Lanzhou Univ., 1989,25,73. Chang, X. J., Luo, X. Y., Zhan, G. Y., and Su, Z. X., J. Lanzhou Univ., 1990, 26, 35. Chang, X. J., Luo, X. Y., Zhan, G. Y., and Su, Z. X., Mikrochim. Acta, 1990, I, 101. Xing, Q. Y., Xu, R. Q., and Zhou, Z., Basic Organic Chemistry, Publishing House of the Advanced Education, Beijing, 1989, pp. 465 and 474. Shi, Y. Z., Kong, X. Z., Zhao, S. N., and Zhu, H. X., Organic Compound Spectra and Chemistry Determination, Publishing House of Jangsu Science and Technology, Nanjing, 1988, pp. 75, 107, 110, 122, 131, 138,474,490, 509, 516 and 522. Dong, Q. N., IR Spectrum Method, Publishing House of the Chemical Industry, Beijing, 1979, pp. 104, 122, 138, 146, 159, and 168. Paper 31046381 Received August 3, 1993 Accepted November 11, 1993

ISSN:0003-2654    

DOI:10.1039/AN9941901445

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, July 1994, Vol. 119 1451 Solid-Liquid Extraction for the Determination of Impurities in High-purity Lead by Atomic Absorption Spectrometry With Electrothermal Atomization Masataka Hiraide, Yasushi Mikuni and Hiroshi Kawaguchi Department of Materials Science and Engineering, Nagoya University, Chikusa-ku, Nagoya 464, Japan After dissolving a lead sample in 4.5 moll-1 nitric acid, the solution was evaporated to dryness. The trace impurities were extracted from lead nitrate crystals with an ethanolic solvent, that is, a 99 + 1 mixture of ethanol (99.5% v/v) and 15 moll-' aqueous ammonia (for silver) or a 99 + 1 mixture of ethanol (99.5% v/v) and 12 mol 1-1 hydrochloric acid (for iron, copper and cadmium). The desired trace metals were recovered in >93% yields and determined by electrothermal atomic absorption spectrometry.The separation factor for the lead matrix was about 10-3. The proposed method was applied to the determination of impurities at ng g-1 levels in high-purity lead metal. Keywords: Lead metal; solid-liquid extraction; ultrasonic irradiation; electrothermal atomic absorption spectrometry Introduction Solid-liquid extraction offers a useful separation technique, where trace constituents in a solid sample are selectively dissolved in an appropriate solvent.1 A solid sample is first dissolved in acids or other solvents and then evaporated to dryness to redistribute the trace constituents on the surfaces or in the interstitial spaces of agglomerates of pure matrix crystals. This technique is simple and often permits the simultaneous multi-element separation of trace elements prior to the instrumental determination step.Mizuike and co- workers studied solid-liquid extraction systematically from the viewpoint of inorganic trace analysis. Different solvents were examined for the extraction of trace impurities from basic bismuth nitrate273 and chlorides4 of sodium, potassium, nickel, cadmium, barium and lead for atomic emission spectrometry and square-wave polarography . For the analysis of lead metal, however, the solid-liquid extraction proposed hitherto has the following disadvantages. The extraction from lead chloride4 requires the conversion of the chemical form of lead from nitrate to chloride before the extraction. In addition, it cannot be applied to the determina- tion of trace amounts of silver because of the very poor extraction recoveries (<4%). Although the combination of solid-liquid extraction with matrix precipitation (as lead nitrate from concentrated nitric acid solutions)5 improved silver recoveries significantly, the procedure was troublesome and time consuming.The separation factor* for the lead matrix is not good (approximately and concentrated nitric acid may be undesirable for most instrumental determi- nation techniques. Because silver is the typical trace constituent in lead metal, it should be determined along with other ubiquitous heavy * Separation factor = (Q'T/Q"M)/(QT/QM). where &is the amount of the trace element in the sample, PM the amount of the matrix element in the sample and QT and QM are the corresponding amounts after the separation.metals. In this work, a mixture of ethanol and aqueous ammonia was found to be most suitable for the quantitative extraction of silver. The combined use of ethanolic ammonia and ethanolic hydrochloric acid allows the direct extraction of silver, iron, copper and cadmium from lead nitrate, with a separation factor of 10-3. This simple separation method was applied successfully to the analysis of high-purity lead by electrothermal atomic absorption spectrometry (ETAAS). Experimental Apparatus A Seiko (Tokyo, Japan) SAS-715 graphite furnace atomizer was used in conjunction with an SAS-760 atomic absorption spectrometer fitted with a deuterium-effect background corrector. Profiles of the analytical signal and background absorption were displayed on a cathode-ray tube incorporated in the instrument.The furnace programme was as follows. The graphite tube, 30 x 6 mm i.d., made of pyrolytic graphite, was first heated during 20 s to 150 "C, held for 10 s and then heated during 5 s to 400°C and held for 15 s; the tube was further heated to atomization temperatures of 2000 "C for 2 s (Ag and Cd) and 2400°C for 4 s (Fe and Cu) for measuring the peak height absorbance. The wavelengths used were Ag 328.1, Fe 248.3, Cu 324.8 and Cd 228.8 nm. Hollow cathode lamps were operated at 10 mA (except for Cd, 5 mA). The evaporation apparatus consisted of a Yamato (Tokyo, Japan) HF 41 heater and an aluminium heating block (12 holes of 25 mm diameter x 65 mm depth), where a Pyrex glass test- tube (20 mm i.d., 24 mm o.d., 100 mm high) containing sample solution (approximately 3 ml) was inserted.The test- tube was sealed with a silicone-rubber stopper bearing two glass tubes. Nitrogen (preliminarily filtered through a 0.1 pm membrane filter) was introduced into the test-tube at a flow rate of 0.5 1 min-l to provide a clean atmosphere and to sweep out evaporating solvents. A Branson (Danbury, CT, USA) ultrasonic cleaning bath (47 kHz, 120 W, 295 x 150 x 150 mm high) was used for the extraction of trace metals from the lead matrix. A sample test- tube was irradiated at a height of 50 mm from the bottom of the ultrasonic bath. A Hitachi (Hitachi, Japan) ECV-843 BY clean-bench was used for separation procedures. Reagents All reagents were of analytical-reagent grade (Katayama Chemicals, Osaka, Japan), unless stated otherwise.Water was purified by distillation and ion exchange, and then passed through a Millipore (Japan Millipore, Yonezawa, Japan) Milli-Q purification system. Standard silver solution. Silver nitrate (100 mg as Ag) was dissolved in 100 ml of 15 mol I-* aqueous ammonia and a 1 ml1452 Analyst, July 1994, Vol. I19 aliquot of the solution (1 mg ml-l Ag) was diluted to 100 ml with ethanol (99.5% v/v). The solution (10 pg ml-l Ag) was further diluted to appropriate concentrations with a 99 + 1 mixture of ethanol (99.5% v/v) and 15 rnol 1-1 aqueous ammonia immediately before use. Another standard silver solution (10 pg ml-1 Ag, in 0.1 rnol 1-l nitric acid) was separately prepared and stored for making synthetic sample solutions.Standard solutions of iron(Iii), copper(ir) and cadmium(ii) . Commercial metal standard solutions were diluted with 12 moll- * hydrochloric acid to prepare stock standard solutions of 100 pg ml-1 Fe, 100 pg ml-1 Cu and 10 pg ml-l Cd. A 1 ml aliquot of each solution was diluted to 100 ml with ethanol (99.5% v/v), then further diluted to appropriate concentra- tions with a 99 + 1 mixture of ethanol (99.5% v/v) and 12 rnol 1-1 hydrochloric acid immediately before use. Other standard solutions (10-100 pg ml-l metal in 0.1 moll-' nitric acid) were also prepared and stored for making synthetic sample solutions. Lead nitrate solution. Pure lead nitrate was prepared by the matrix precipitation method,6 in which the lead was precipi- tated as nitrate from concentrated nitric acid solution. A 1.5 g amount of lead metal (1-2 mm granular form) was dissolved in 10 ml of 4.5 moll-' nitric acid.The solution was evaporated to form a moist crystal conglomerate, which was then treated with slight heating with 15 ml of 14 rnol 1-l nitric acid. After cooling, the acid was removed by centrifugation. The lead nitrate crystals were washed twice ultrasonically with 10 ml portions of 14 moll-' nitric acid without heating. The purified precipitate was dissolved in water (usually 20 ml). The concentration of lead was standardized by AAS. The purifica- tion method was very effective because no contamination was detected for silver, iron, copper and cadmium. Procedure A 3 ml volume of lead nitrate sample solution (containing 100- 300 mg of lead) was placed in a Pyrex glass test-tube and evaporated to dryness by heating at 100°C for 30 min and further heating at 140 "C for 10 min.The residue was cooled to room temperature and pulverized manually for 1 min with a Teflon rod (5 mm diameter). After adding 2-5 ml of extraction solvent, the test-tube was closed tightly with a silicone-rubber stopper and irradiated with ultrasound for 30-60 min. The extraction solvent was separated by centrifugation (lO00g for 10 min) and 10 pl aliquots of the solvent were transferred into the graphite furnace for the determination of silver, iron, copper and cadmium by QTAAS. The measurement was repeated three times and the absorbance readings were averaged. Calibration graphs were prepared by using ethanolic standard solutions containing appropriate amounts of trace metals.Results and Discussion Selection of Solvents for Extracting Trace Metals From Lead Nitrate Suitable solvents were surveyed from the viewpoints of (1) high solubility of the desired trace metals, (2) minimum solubility of the lead matrix and (3) no interference with subsequent determination by ETAAS. Because the utility of ethanol containing small amounts of hydrochloric acid had been previously reported for the extraction of iron, cobalt, copper and zinc from lead chloride,4 99 + 1 and 999 + 1 mixtures of ethanol (99.5% v/v) and 12 rnol 1-l hydrochloric acid were examined in this work. A 3 ml volume of lead nitrate solution (containing 100 mg of lead and nanogram amounts of trace metals) was evaporated to dryness and then treated ultrasonically for 3040 min with 5 ml of different kinds of extraction solvents (see Procedure).As shown in Table 1, a mixture of ethanol (99.5%) and 12 rnol I-' hydrochloric acid was effective for the extraction of iron, copper and cadmium from lead nitrate, although it was not useful for silver. Compared with a 999 + 1 mixture, a 99 + 1 mixture always provided quantitative trace recoveries. On the other hand, trace amounts of silver were nearly completely extracted into a 99 + 1 mixture of ethanol (99.5% v/v) and 15 moll-' aqueous ammonia. A significant amount of cadmium was also extracted along with the silver, but the recovery was insufficient and variable. Small or negligible extractability was observed for copper and iron, respectively.Pulverization of the evaporation residue with a Teflon rod was helpful for complete extraction. Without trituration, the trace recoveries were decreased by 3-10%. The lead accom- panying the trace metals was determined by ETAAS and found to be 120-150 pg, which did not interfere in the subsequent determination of trace metals. The separation factor for the lead matrix can be calculated to be (1.2-1 S) x 10-3. Effect of Extraction Time on Trace Recovery Ultrasonic irradiation is known to increase substantially the extraction of trace elements,4 probably owing to the pulveriza- tion of solid particles and adequate mixing. Fig. 1 shows the percentage of trace metals extracted into 2 ml of solvent as a function of ultrasonic irradiation time.With a 99 + 1 mixture of ethanol (99.5% v/v) and 15 mol 1-I aqueous ammonia, Table 1 Extraction of trace amounts of silver(i), iron(rrr), copper(i1) and cadmium(i1) from 100 mg of lead Trace Extrac- Trace metal tion metal Amount extracted Extraction solvent time/min added addedng (YO) Ethanol-12 moll- HCI 60 Ag 5 7 (999 + 1) Fe 50 87 60 Ag 25 2 c u 50 86 Cd 5 89 Fe 250 94 c u 250 82 Cd 25 98 Ethanol-12 rnol I- HCl 60 Fe 50 97 (99 + 1) c u 50 94 Cd 5 96 60 Fe 250 93 c u 250 94 Cd 25 96 Ethanol-15 rnol I-' 30 Ag 5 87 aq.NH3 (999 + 1) Fe 50 0 c u 50 18 Cd 5 67 30 Ag 25 90 Fe 250 0 c u 250 19 Cd 25 89 0 c u 50 27 Cd 5 60 30 Ag 25 95 Fe 250 0 c u 250 20 Cd 25 56 Ethanol-15 rnol I-' 30 Ag 5 93 aq. NH3 (99 + 1) Fe 50Analyst, July 1994, Vol. 119 2.07. 1453 1/2t nearly complete recovery (>%YO) was attained after 30 min (for silver) and after 60 min (for cadmium).Copper and iron were hardly extracted even after 60 min. On the other hand, iron, copper and cadmium behaved similarly with ethanol (99.5% v/v)-12 moll-' hydrochloric acid (99 + l), showing a recovery of 9698% with irradiation for 60 min. More than 90% of silver remained unextracted, however. The volume of extraction solvent was not changed even after 60 min, because the test-tube was tightly sealed with a silicone-rubber stopper. P J 20 40 L A I n n - v v - v 0 20 40 60 Ultrasonic irradiatiodmin Fig. 1 Effect of ultrasonic irradiation on the extraction of silver (10 ng, A), iron (100 ng, D), copper (100 ng, C) and cadmium (10 ng, B) from 100 mg of lead matrix with a 2 ml mixture of (a) ethanol and 15 rnol I-' aqueous ammonia (99 + 1) and (b) ethanol and 12 mol 1-l hydrochloric acid (99 + 1).Effect of Amount of Lead on Extraction Recovery After evaporating 3 ml of lead nitrate solution (containing nanogram amounts of trace metals and 1W500 mg of lead), the residue was treated ultrasonically with 2 ml of extraction solvent. Silver was extracted with a 99 + 1 mixture of ethanol (99.5% v/v) and 15 moll-' aqueous ammonia for 30 min; iron, copper and cadmium were extracted with a 99 + 1 mixture of ethanol (99.5% v/v) and 12 rnol 1-1 hydrochloric acid for 60 min. Table 2 shows that trace metals are extracted in >94% yields from a solution containing 100-300 mg of lead, but the trace recoveries decrease slightly in the presence of 500 mg of lead. Analysis of High-purity Lead Metal The proposed separation method was applied to the analysis of high-purity lead.A 2 g sample of commercial lead metal (99.999% purity, 2-3 mm granular form; Katayama Chem- icals) was dissolved in 15 ml of 4.5 rnol I-' nitric acid; the solution was evaporated to dryness and the residue was dissolved in 20 ml of water. A 1 ml aliquot of the solution was placed in a test-tube and evaporation, extraction and determi- nation were carried out as described under Procedure. The results are summarized in Table 3. Good reproducibili- ties were obtained for trace constituents, with relative standard deviations of 2 4 % . A 10 ng amount of silver added to the sample was quantitatively recovered and successfully determined.Blank values through the whole procedure were less than the detection limits: ~ 0 . 5 ng for silver, <2 ng for iron, <2 ng for copper and C0.5 ng for cadmium. Table 2 Effect of amount of lead matrix on trace recovery Trace metal extracted (YO) Lead taken*/mg Agl Fell' CU" Cd" 100 97 102 101 99 200 97 99 99 99 300 94 98 98 96 500 76 90 89 90 * Amounts added were Ag 10 ng, Fe 100 ng, Cu 100 ng and Cd 10 ng. Table 3 Determination of impurities in high-purity lead (99.999% purity) Aliquot Sampldg taken 1/10 1/2* 1/10 Fo u n d/ng Concentrationhg mg- Ag Fe c u Cd Ag Fe c u Cd 54 55 13.0 0.52 0.53 0.125 50 52 14.0 0.48 0.50 0.135 53 54 12.7 0.51 0.52 0.122 54 55 13.1 0.52 0.53 0.126 53 54 13.0 0.51 0.52 0.125 Average 0.51 0.52 0.127 13.7 14.1 13.0 13.4 12.7 23.0 0.132 0.136 0.125 0.129 0.122 0.125 Average 0.128 * Extraction with ethanol-12 rnol 1-1 hydrochloric acid. + Extraction with ethanol-15 mol I-' aqueous ammonia. * 10 ng of Ag were preliminarily added.1454 Analyst, July 1994, Vol. 119 References 5 Mizuike, A., and Fukuda, K., Mikrochim. Acta, 1975, I, 281 1 Mizuike, A., Enrichment Techniques for Inorganic Trace Jackwe*h7 E*7 pure Appl. lg7” ‘14’* Analysis, Springer, Berlin, 1983, p. 52. 2 Mizuike, A., Kawaguchi, H., and Kono, T., Mikrochim. Acta, 1970,1095. 3 Mizuike, A., and Fukuda, K., Mikrochim. Acta, 1972,257. 4 Mizuike, A., Fukuda, K., and Ochiai, Y., Talanta, 1972, 19, 527. Paper 3107070K Received November 29, 1993 Accepted February 2, 1994

ISSN:0003-2654    

DOI:10.1039/AN9941901451

出版商:RSC    

年代:1994

数据来源: RSC