ISSN:0003-2654    

DOI:10.1039/AN99419FX013

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

ANALAO 119(4) 481-714, 41N-54N (1994) APRIL 1994FOREWORDPLENARY LECTURESINVITED LECTURES'""An al y s tThe analytical journal of The Royal Society of ChemistryCONTENTS481 XXVlll Colloquium Spectroscopicum lnternationale (CSI), York, 29th June4th July, 1993-Edward Steers483 Multidimensional Gas Chromatography-Infrared Spectrometry-Mass Spectrometry-Kevin A Krock, NRagunathan, Christoph Klawun, Tania Sasaki, Charles L. Wilkins491 Enhanced Waveguide Raman Spectroscopy With Thin Films-S. Ellahi, R. E. Hester497 Tandem Mass Spectrometry for the Determination of Deoxyribonucleic Acid Damage by PolycyclicAromatic Hydrocarbons-Joelle Wellemans, Ronald L. Cerny, Michael L. Gross505 Evidence for Changes in the Conformation of Flexible Solutes Dissolved in SupercriticalSolvents-Jeanette K.Rice, Steven J. Christopher, Upvan Narang, William R . Peifer, Frank V. Bright51 3 Impact of Mass Spectrometry in Surface Analysis-John C. Vickerman525 Laser Photoacoustic Spectrometry for Trace Gas Monitoring-Markus W. Sigrist533 Multiple Stage Mass Spectrometry: The Next Generation Tandem Mass Spectrometry Experiment-Gary L.Glish539 Developments in Spectroscopic Data Handling-Antony N. Davies543 Luminescence Lifetimes in Biological Systems-D. Phillips551 Nanosecond Time-resolved Infrared Spectroscopy: a Comparative View of Spectrometers and TheirApplications in Organometallic Chemistry-Michael W. George, Martyn Poliakoff, James J Turner561 Laser-induced Photoacoustic Signal Phase Study of Stratum Corneum and Epidermis-M. L.Baesso, JShen, R . D. Snook563 Comparison of Fourier Transform Raman Spectra of Mammalian and Reptilian Skin-Adrian C. Williams,Brian W. Barry, Howell G. M. Edwards567 Surface-enhanced Raman Spectroscopy of 9-Phenylacridine on Silver Sol-T. Iliescu, I. Marian, R. Misca,V. Smarandache571 Direct Determination of Polycyclic Aromatic Hydrocarbons in Environmental Matrices Using LaserDesorption Laser Photoionization Time-of-flight Mass Spectrometry-Michael J. Dale, Anita C. Jones,Simon J. T. Pollard, Patrick R. R. Langridge-Smith579 Laser Mass Spectrometry of a Frozen Water Matrix in Environmental Analysis-Sergue S. Alimpiev, MikhailE. Belov, Victor V. Mlinsky, Sergue S. Nikiforov583 Real-time Biomolecular Interachon Analysis Using the Resonant Mirror Sensor-Nicholas J.Goddard,Denise Pollard-Knight, Colin H. Maule589 Application of 57Fe Emission Mossbauer Spectroscopy to the Investigation of the Physico-chemicalConsequences of the Double Radioactive Decay 57Ni-FCm57Fe in the Solid State-Michel Devillers,Jean LadriereChemical Effects on the Intensity of Ti Kq (Radiative Auger Satellite) X-ray Fluorescence Spectra-JunKawai, Takayuki Nakajima, Takehiro Inoue, Hirohiko Adachi, Masaharu Yamaguchi, Kuniko Maeda,Sadayo Yabuki605 Ionic Reaction Mechanisms in Pre-mixed Flames Disclosed by Stable-isotope Labelling-Helge Egsgaard,Elfinn Larsen, Lis Vinther Kristensen, Per Solgaard, Lars Carlsen609 Chemical Study of Passivating Chromium Oxide Films by Soft X-ray Absorption Spectroscopy-M.0.Figueiredo, A. Correia dos Santos, M. J. Carmezim, M. Abbate, F. M. F. de Groot, H. Petersen, W. Braun61 3 Improved Neutron Activation Analysis With Short-lived Nuclide Decay Compensation-Neophytos NPapadopoulos, Nicolas F. Tsagas61 7 Determination of Precious Metals in Rocks by Inductively Coupled Plasma Mass Spectrometry Using NickelSulfide Concentration. Comparison With Other Pre-treatment Methods-Riitta Juvonen, Eeva Kallio, TuulaLakomaa623 Determination of Metals in Sediments of Sinamaica Lagoon, Venezuela by Atomic AbsorptionSpectrometry-Marinela Colina de Vargas, Hilda Led0 de Medina, Katiuska AraujoCONTRIBUTED PAPERSAND POSTERS601Continued on h i d e Back Cover-Typeset and printed by Black Bear Press Limited,Cambridge, EnglanNEWS AND VIEWS62763364 164765365966567 167768368969369770370971 3Simultaneous Determination of Chromium(iti) Complexes and Chromium(vi) by Fast ProteinAnion-exchange Liquid Chromatography-Atomic Absorption Spectrometry-Radmila MilaCiC, JanezStuparStudies on the Breakdown of Organoselenium Compounds in a Hydrobromic Acid-Bromine DigestionSystem-Alessandro D'Ulivo, Leonard0 Lampugnani, llias Sfetsios, Roberto Zamboni, Claudia ForteHigh-field Magnetic Resonance Studies of the Molecular Motion of tert-Butyl Compounds in Liquid and SolidPhases: the Binary System tert-Butyl Iodide-Carbon Tetrachloride-Dagfinn W.Aksnes, Liudvikas KimtysStabilization of the Peptide Conformation on the Micellar Surface-Yu. E. Shapiro, V.Ya. Gorbatyuk, A. A.Mazurov, S. A. AndronatiSimultaneous Flow Analysis Fourier Transform Infrared Determination of Benzene, Toluene, and Methylt-Butyl Ether in Petrol-Maxim0 Gallignani, Salvador Garrigues, Miguel de la GuardiaOn-line Preconcentration and Flow Analysis-Fourier Transform Infrared Determination ofCarbaryl-Salvador Garrigues, Ma Teresa Vidal, Maximo Gallignani, Miguel de la GuardiaQuantitative Analysis of Small Volumes of Gas Mixtures by Fourier Transform Infrared Spectroscopy-M. T.Gaudez, H. Pitsch, J. Florestan, J. C. BoulouApplication of Drift Spectroscopy and Chemometrics to the Discrimination of Dye Mixtures Extracted fromFibres from Worn Clothing-Serge Kokot, C. GilbertComparative Study of Metal Ion Interactions With Wool Keratin Using Chemometrics-Serge Kokot, JingCheng, Nigel GillApplication of Infrared Spectrometry to the Study of Tautomeric Equilibria and Hydrogen Bonding Basicity ofMedical and Biochemical Agents: N,N'-Disubstituted Amidines-Ewa D.Raczynska, Christian Laurence,Michel BerthelotInfrared and Nuclear Magnetic Resonance Studies of Some Surface Properties of Asbestos-AlbuminInteractions-Rodica Dumitru-StBnescu, Cristina Mandravel, Cristiana BercuAnalysis of Polymers Using Evolved-gas and Direct-pyrolysis Techniques-Mohammed M. Fares, TalatYalcin, Jale Hacaloglu, Atilla Gungor, Sefik SuzerSecond-derivative Spectrophotometric Determination of Naproxen in the Presence of its Metabolite inHuman Plasma-I, Panderi. M. Parissi-PoulouDetermination of Selenium in Biological Matrices Using a Kinetic Catalytic Method-I. G. Gokmen, EAbdelqaderSensitive Determination of Sulfur Concentration in Steel by Spectrophotometry With a Waveguide CapillaryCell-Koichi Chiba, lsamu Inamoto, Kin-ichi Tsunoda, Hideo AkaiwaCUMULATIVE AUTHOR INDEX41N Book Reviews45N Conference Diary51N Courses52N Papers in Future IssuesCover picture: Illustration of York Minster, reproduced by kind permission of the Dean and Chapte

ISSN:0003-2654    

DOI:10.1039/AN99419BX015

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

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An innovative out-of-plane instrumentation.accessories, software, and Cary'suniquely flexible ApplicationsDevelopment Language (ADL).It's clear why the new Cary 4Eand 5E outperform all competitivemonochromator offers resolution ofless than 0.05 nm and an extendeddynamic range in excess of 6Find out why Cary is the bestspectrophotometer money can buy.absorbance.This outstanding optical performanceis combined with unsurpassedVarian Ltd28 Manor RoadWalton-on-ThamesSurrey KT12 2QFTel: (0932) 243 741The Genesis CentreBirchwood Science ParkWarringtonCheshire WA3 7BHTel: (0925) 811 422GC G W S GChlShIS HPLC M S ICP-AES ICP-MS UV-Vis-NIR NMR LIMS Sample Preparation Vacuum ProductEIGHT PEAKINDEX OF MASSSPECTRA4th EditionThe essential tool formass sp ectrometristsThis quality compilation is recognised bymany mass spectrometrists as the mostuseful index of mass spectra in print today!THE EIGHT PEAK INDEX EMPOWERS YOU TO:* identify unknowns rapidly and easily * locate spectra of compounds quickly by formula or molecular weight * match spectra simply through direct peak intensity comparison * find spectra relevant to your area of interest - a wide variety of* access the data at any time with no machine-time restrictions * use the data with confidence - extensive checks on all records havecompound types are includedbeen performedROYALSOCIETY O FCHEMISTRYI n for ma t ionS e r v i c-cl sProbably the best printed indexof mass spectra in the world!For more information about the latest edition, simply contactus at the address below for a copy of our detailed leaflet:Sales and Promotion DepartmentRoyal Society of ChemistryThomas Graham HouseScience Park, Milton RoadCambridge CB4 4WF, United KingdomTel: +44 (0) 223 420066Fax: +44 (0) 223 423623E-mail: (Internet) MARKETING@RSC.ORHEMICAL SAF ETY DATA SHEETSWould you know what to do in an emergency such as achemical spill or explosion?Are you up-to-date with the procedures necessary for thesafe handling of hazardous chemicals?The Chemical Safety Data Sheets series provides the informationyou need to quickly and accurately assess the risks associatedwith a chemical and how to prevent accidents.The data sheetsare clearly and systematically presented to provide an ideal refer-ence format for fast scanning and assessment. 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ISSN:0003-2654    

DOI:10.1039/AN99419BP019

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, April 1994, Vol. I19 4 1 ~ Book Reviews UV-VIS Spectroscopy and Its Applications By Heinz-Helmut Perkampus. Pp. x + 244. Springer- Verlag. 1992. Price DM168.00. ISBN 3-540-55421-1; 0-387- 55421-1. Although recent years have seen the introduction and growth of several new techniques in analytical chemistry, UV-visible spectroscopy remains a major and indeed an indispensible technique. The present volume on this subject is a translation of the second German edition and forms a useful addition to the numerous available texts. Theory and instrumentation are given relatively short treatment and the bulk of the text is devoted to applications of UV-visible spectroscopy in analy- tical and physical chemistry. The more recent developments such as derivative, reflec- tance and photoacoustic spectroscopy are outlined, along with appropriate examples of the uses of these newer techniques.Studies of chemical equilibria in solution very frequently involve spectrophotometry and an instructive chapter is devoted to the methods of such measurements. Similarly, there is an informative account of the application of UV- visible spectrometry to the investigation of the kinetics of chemical reactions. It is, perhaps, understandable and to some extent, accept- able that a text based on the author’s lectures to his students may not be too comprehensive, and discussions of applications are, in some areas, rather limited. (For example, flow methods are described only in connection with kinetic studies.) Nevertheless, graduate students of analytical chemistry should find much in this book to supplement their own lecture notes. As a guide to other scientists who may have to have recourse to spectrophotometric methods to solve particular problems, the book provides a useful introduction and source of further information.Perhaps the least attractive feature of the book is its cost, exacerbated by the unfavourable DM-sterling exchange rate. Unfortunately, this must have an adverse effect on the possible purchase of the book by those who might benefit most by its acquisition. W. I . Stephen Radiochemistry and Nuclear Methods of Analysis By William D. Ehmann and Diane E. Vance. Pp. xx + 532. Wiley-lnterscience. 1993. Price f41.50. ISBN 0-471 -30628-2. The first, and most positive, thing to be said about this book is that it is well written and readable.The authors are experienced not just in the practice of radiochemistry, but in its teaching, and this shows in the clarity of the text. The book is not intended as a detailed theoretical treatment, but rather as a descriptive guide to how radioactive isotopes, and processes involving their production, can be used in chemistry, and particularly analytical chemistry. In general, the book succeeds in these aims: a chemistry undergraduate should be able to understand without difficulty the theory that is presented, and any reader-whether a student or a practitioner in another area of chemistry-should get a good feel for the range of applications of radioisotopes. It is important to recognize that the book is not aimed at the specialist radiochemist, interesting though they may find it.‘Any reader-whether a student or a practi- tioner in another area of chemistry-should get a good feel for the range of applications of radioisotopes.’ Given the general and descriptive aims of the book the selection of material to be covered is vital, and this is always a matter of personal preference. Thus one could question the need for parts of Chapter 3 on Nuclear Structure and Chapter 4 on Nuclear Energetics, since they are scarcely developed subsequently. Similarly, Chapter 13 on the Origin of the Chemical Elements, although interesting, hardly merits the detailed treatment it receives. But more important are the omissions. Liquid scintillation counting surely needs more than the solitary page it receives.Radioimmunoassay is covered in two pages: in a book that puts such an emphasis on analytical applications this is extraordinary. RIA is such an important analytical method that most would consider it merits a depth of treatment approaching that of the excellent Chapter 9 on Nuclear Activation Analysis. The latter is the best general guide to NAA of which this reviewer is aware, and clearly owes much to Professor Ehmann’s eminence in this field. In summary, this is an interesting and readable book which should stimulate the reader to delve further into more specialized material. It is very well produced and illustrated, though whether it is ‘the first practical, comprehensive guide to the science of radiochemistry’ as claimed, is doubtful. Sadly, at Z41.50, it is outside the pocket of the individual student, but it should be an essential purchase for libraries wherever analytical chemistry is practised.W. J . Geary Scanning Tunneling Microscopy and Spectroscopy. Theory, Techniques and Applications Edited by Dawn A. Bonnell. Pp. xiv + 436. VCH. 1993. Price DM1 96.00; f80.00. ISBN 0-89573-768-X (VCH Publishers, Inc.); 3-527-27920-2 (VCH Verlagsgesellschaft). Over the last decade scanning tunneling microscopy (STM) has developed from the use of a prototype experimental instrument to a routine tool for the analysis of organic and inorganic materials. The level of resolution of STM, and the scanning probe techniques that have since been developed, has provided a major step forward in the understanding of interfacial systems at the atomic level.With commercial instruments now available from a number of manufacturers, there is a direct need for monographs on this technique for research scientists, especially those who are new to this technique. This book aims to provide this information with a wide ranging review of the technique and its associated theories and applications. ‘Overall this text is a valuable summary of STM instnunentation, theory and its applications and will be of great value to researchers, especially those who are new to this exciting field of research.’ This multi-author book, written by experts in the field, attempts to cover many of the pivotal issues in STM, including instrumental design and the mechanism of contrast formation42N Analyst, April 1994, Vol.11 9 in biological applications of the technology. In general, it is well written and produced, and imparts sound background knowledge to the reader. This is particularly true of Part I, the first four chapters of the book, which examines the fundamen- tals of STM. In particular, the chapter by Tersoff provides a very valuable discussion on the theory of STM imaging process, including the tipsample interactions. The two chapters of Part I1 of the book examine the structure of sample and tip surfaces. This section is relatively disappointing (especially the chapter on crystalline solids, which, although complete, has the role of STM in such analysis apparently tagged on as an after thought). The book concludes with Part I11 which examines related techniques and applications.I would highly recommend the excellent chapter by Lindsay covering all aspects of biological applications of scanning probe microscopy and the very valuable review of force microscopy by Burnham and Colton, which includes a superb section on the interpretation of force microscopy results. In addition, the excellent chapter by Bard and Fan on STM applications in electrochemistry is well worth reading. How- ever, the relevance of the chapter on ballistic electron emission spectroscopy is less clear, this might have been replaced with a more appropriate review on STM studies of monolayers. Overall this text is a valuable summary of STM instrumen- tation, theory and its applications and will be of great value to researchers, especially those who are new to this exciting field of research.Saul J. B. Tendler Working Materials. All the important points with regard to definitions, purposes, applications and directions are, in general, well addressed. One of my personal preferences is the regular size of this report in comparison to the smaller booklet from the ACGIH, which is often not easily located in a fully stacked bookshelf. Also, I always feel that the contents in the latter are crammed together and make it difficult to read. In contrast, the illustrations, descriptions and tables of this report are much more easily referred to. I particularly like that, in the MAK value table, the chemical structures of all the listed substances are given. It definitely can minimize the substance identifica- tion errors for many occupational health workers who are not strongly chemistry oriented.There are, however, some areas in this report that are less clearly presented to the reader. In the table of Limitation of Exposure Peaks on page 10, the columns of level, duration regarding short-term exposure and frequency per shift are not well explained. For example, one can only guess that values such as 2.MAK, 5.MAK and 10-MAK mean 2-, 5- and 10-fold MAK, or are they? If so, why 2-, 5- and 10-fold? The same can be said for values in duration and frequency. Some representa- tive cases perhaps should be cited in order to explain this table better. Also I could not find the explanation of those compounds marked with stars in section I11 and in the sub- sections ( b ) and ( c ) of section 11.A similar situation was also observed in section VII, the List of Compounds for BAT Values. Weh-sai Wu MAK- and BAT-Values 1992. Maximum Concentrations at the Workplace and Biological Tolerance Values for Working Materials By the Deutsche Forschungsgemeinschaft. Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area. Report No. 28. Pp. 116. VCH. 1993. Price DM38.00. ISBN 3-527-27554-1. DECHEMA Corrosion Handbook. Corrosive Agents and Their Interaction with Materials. Volume 10. Carboxylic Acid Esters, Drinking Water, Nitric Acid Edited by Gerhard Kreysa and Reiner Eckermann. Pp. x + 308. VCH. 1992. Price DM 775.00; f286.00. ISBN 3-527- 26661 -5 (VCH Verslagsgesellschaft); 0-89573-631 -4 (VCH Publishers). This annual report regarding ‘the Maximum Concentrations (MAK) at the Workplace and Biological Tolerance Values (BAT) for Working Materials’ in Germany is more or less equivalent to the booklet of the Threshold Limit Values (TLV) for Chemical Substances and Physical Agents and Biological Exposure Indices (BEI) published annually by the American Conference of Governmental Industrial Hygienists (ACGIH). Although the ACGIH annual booklets are fre- quently referred to in North America by occupational health workers, this is the first time that I have the opportunity to read the German version of the ACGIH equivalent booklet.Since MAK and BAT are the guide values in Germany, and have been derived from the German perpsective, my com- ments on this report, therefore, are not technical but are more general with a certain degree of comparison with the ACGIH booklet .‘All the important points with regard to defii- tions, purposes, applications and directions are, in general, well addressed.’ This report contains two major parts, maximum concentra- tion at the workplace, and biological tolerance values for working materials. The former part contains five sections. The first four as follows: I, Significance and Usage of MAK Values; 11, Lists of Compounds; 111, Carcinogenic Working Materials; IV, Special Working Materials. The fifth part contains three sections: VI, Significance and Usage of BAT Values; VII, Lists of Compounds; and VIII, Carcinogenic Corrosion is something that affects us all. Its most direct and immediate impact is upon our pockets as, for example, we see hard earned cash spent on the latest offering from the motor industry literally being eaten away.We also suffer indirectly, for the nation as a whole loses a few per cent per annum of its GNP as a result of corrosion. But it is not just a question of economics that makes corrosion such a blight on our lives, it can give rise to aesthetic blots on the landscape, whether it be the rust stain permeating the walls of buildings from corroding embedded steel supports or in the abandoned industrial factory sties and works that are becoming an increasingly familiar feature of the urban landscape. More seriously it can lead to failure of materials, which in turn can cause accidents and personal human tragedies, such as happened some years ago at Flixburgh, An understanding of the factor affecting corrosion and its reduction and prevention is therefore a matter of great significance and importance.Yet the phenomenon of corro- sion is by no means a simple process as it involves, among other things, thermodynamics and kinetic considerations, materials science, mechanical engineering, surface treatment, environmental technology and, of particular interest to the readers of The Analyst, chemical analysis and materials testing. No wonder, therefore, that corrosion has been, and continues to be, intensively studied by scientists and engineers from a wide range of disciplines and backgrounds. This has inevitably lead to a plethora of publications, and to follow the whole spectrum of developments in corrosion science and engineering would involve a great deal of time and effort byAnalyst, April 1994, Vol.11 9 43N anyone working in the area, let alone by anyone wishing to learn about the latest discoveries and trends. To help in this process there has been over the last 40 years or so a series of handbooks published as the Dechema- Werkstoff- Tabelle, otherwise known as the Dechema Corrosion Data Sheets. In this series the behaviour of a wide range of materials, and not just those that are iron based, in contact with more than a thousand different types of corrosion media have been reviewed with characteristic German thoroughness and atten- tion to detail using more than 250000 citations. This volume is the latest in the series and examines the interaction between carboxylic acid esters, drinking water and nitric acid, and several hundred different types of materials ranging from iron- based alloys and other metallic materials, through non- metallic inorganic materials such as glasses, refractories and ceramics, to organic material such as natural fibres, wood, plastics and other synthetic materials. All of this is done in about 300 pages and inevitably, whilst it is very thorough in terms of factual content, it lacks any guiding or underlying fundamental considerations.So, for example, little is said about the basic electrochemistry of metallic corrosion pro- cesses or about the mechanisms of attack by the media being considered. In other words, it is largely an empirical collation of data, which unfortunately does not extend to giving any case studies and practical guidelines based upon the data.Nevertheless, as has already been indicated, in an area such as corrosion where the published material is extensive, this volume, with its earlier companion volumes, does provide a useful summary of what is in the literature, even though a large number of the references are of German origin and also not that recent. As the editors point out in their Preface, the volume will be useful for corrosion specialists, process and production engineers, plant and equipment constructors, designers, students of mechanical engineering, chemistry and materials science, and engineers in the electrochemical, plastics and food industries. Such individuals may find the cost of 2286 rather high, but certainly the library of any institution where corrosion science and engineering plays an important part in teaching or research should have this volume, together with its antecedents, on the shelves. It is doubtful, though, that many readers of The Analyst would find this series, in general, and this volume in particular, to be of great interest or value for studies in analytical chemistry.Michael L. Hitchman Chemically Modified Silica Surfaces in Chromatography. A fundamental Study By Martin J. J. Hetem. Pp. ix + 176. Hutnig. 1993. Price DM 198.00. ISBN 3-7785-2030-X. Although much has been written about silica in recent years, this book provides a concise yet comprehensive summary of the derivatization chemistry of silica. The volume concen- trates primarily on the chemistry associated with creating bonded phases of all types and hence extensive use is made of 29Si NMR to characterize products and reactions.Chromato- graphic performance is of secondary importance to the use of ‘The volume concentrates primarily on the chemistry associated with creating bonded phases of all types and hence extensive use is made of 29Si NMR to characterize products and reactions.’ chromatographic parameters and test mixtures to probe the properties of the derivatized silica. Once prepared, the long term stability of the derivatized surfaces are studied by monitoring chromatographic performance against exposure to varying degrees of aggressive solvents. Overall, the subject receives comprehensive treatment and thus will help users of liquid chromatography to understand the behaviour of their columns and hence to achieve better performance and longer lifetimes.Although not a book that is easily read, it is one that can be referred to frequently in order to provide rational explana- tions of observed phenomena. M . Cooke Bioanalytical Approaches For Drugs, Including Anti-asth- matics and Metabolites Edited by Eric Reid and Ian D. Wilson. Methodological Surveys in Biochemistry and Analysis. Volume 22. Pp. xiv + 356. Royal Society of Chemistry. 1992. Price f75.00. ISBN 0-85186-236-5. This book is the 22nd in the series, it is based on the proceedings of the Ninth International Bioanalytical Forum held in September 1991. The book consists of four sections, on Metabolite Investigation, Method Development and Optimi- sation Strategies, Anti-asthmatics and Kindred Agents and Bioanalytically Exploitable Techniques.At the end of each section, there are appended short ‘notes’ (were these poster presentations?) and a summary of the forum comments on the papers. The layout was not well designed, as I found the book difficult to read. This was despite the Editor’s claims that the book had ‘escaped being mere Conference Proceedings’. I was left with the impression that the structure and logic of the layout was fundamentally due to the Conference programme. As an analytical chemist (not involved with metabolism studies) I did find the section on Method Development and Optimisation Strategies a good general introduction to the area. The literature compendium on Drug Assay or Metabol- ite delineation was equally useful.Indeed I found a number of papers, which would be of interest to most analytical chemists, particularly if they are interested in the various methods of sample preparation and extraction. The introductory paper in the anti-asthmatics section was an excellent introduction to the analytical challenges of working in this area. The papers that followed did underline the important role chemical analysis plays in understanding the pharmacology of the disease. In conclusion, I felt that this book would probably be of most use to two main groups; to the delegates who attended the conference, and to new recruits as an introduction to the field of analysis of drug metabolites. It would also be a worthwhile addition to the site library.M . J . Hardy Polymer Characterization Edited by 6. J. Hunt and M. I. James. Pp. xiv + 362. Blackie Academic & Professional. 1992. Price f69.00. ISBN 0- 751 4-0082-3. This multi-authored book contains some 11 chapters, each specifically dedicated to a particular area of polymer charac- terization. There is a brief introductory chapter, which serves only as an extended contents guide. The next chapter describes the separation of additives from polymeric matrices and their quantification using classical volumetric and gravimetric procedures and instrumental techniques such as infrared spectrometry, and gas and liquid chromatography. A range of polymer types, are covered, and44N Analyst, April 1994, Vol. 11 9 methods for the determination of heat stabilizers, anti-oxi- dants, UV-absorbers, antistatic additives, fillers and pig- ments, hindered amine light stabilizers (HALS) and lubricants are described in detail.The chapter also includes general analytical schemes which can be applied to the selective separation and characterization of the components in parti- cular classes of plastic formulation (e.g., polyamides). From an analytical perspective, this chapter is perhaps the most valuable practical contribution in the book as a whole. Molecular spectroscopic techniques are widely used in the characterization of polymeric materials, and two chapters of the book are devoted to this area. It is undoubtedly true that NMR plays a pivotal role in the elucidation of polymer structure, and approximately 20 pages are devoted to this topic.There is a brief introduction to theory of NMR and instrumentation, and an outline of the principles of proton and carbon-13 solution measurement. The effect of polymer chain stereochemistry on proton and carbon chemical shifts is illustrated with reference to common polymers and the issues of quantification based on line intensities are briefly addressed. The latter part of the chapter deals with the growing topic of solid state NMR of polymers using magic angle spinning, and a few examples of the use of 2-D NMR to avoid spectral overlap in both solution and solid state measurements. Vibrational spectroscopy, primarily in the form of infrared and Raman techniques, are covered in a review of the field with a comprehensive reference list.The chapter begins with some useful general comments about the differences between polymer vibrations in comparison with those of small mole- cules. The following section gives an overview of the development of FTIR and FT-Raman instrumentation, sam- pling procedures (e.g., ATR, MIR, DRIFT) and data handling. The remainder of the chapter deals with the application of the techniques described to qualitative and quantitative characterization of polymer systems, including copolymer composition and sequencing, polymer branching and end-group measurements, and studies of polymerization kinetics, degradation, and morphology. Overall, this is a useful summary of the state-of-the-art of vibrational spectro- scopy as applied in a problem solving situation.Chapter 6 introduces chromatographic methods including gas, liquid, size exclusion, thin layer, supercritical fluid and field flow fractionation approaches. The principles involved in each technique are reviewed, and the instrumentation, in terms of column technology and detector system are des- cribed. There is the occasional example of the use of chromatography as a sample presentation method for spectro- scopic techniques such as MS and FTIR, but a subject of such size and complexity ought to have been addressed more extensively, preferably in a separate chapter. Certainly the omission of a review of the application of mass spectrometry in its own right is perplexing in a book that purports to represent the characterization of polymeric systems. Instead, there are chapters on mechanical and rheological testing, neutron scattering, molecular mass determination, thermal analysis, and microscopy, most of which are written from the physical rather than analytical science perspective.The final chapter on surface analysis provides a useful reminder of the interface between these disciplines. However, the book suffers greatly from the brevity enforced by the limit on size. The selection and ordering of the subject matter by the editors is somewhat random, but the book is well presented with clear diagrams, extensive references, and a good index. As an analytical chemist working in the industrial polymers area, I doubt if I would seek to purchase this book, as it contains much that is already familiar. It may be of interest as a general text for libraries with a specific remit to cover the field of materials research.John Marshall Quality Assurance for Analytical Laboratories Edited by M. Parkany. RSC Special Publication No. 730. Pp. xiv + 198. The Royal Society of Chemistry. 1993. Price f39.50. ISBN 0-85186-705-7. Since 1981, there has been a series of IUPAC, I S 0 and AOAC sponsored symposia on the harmonization of various aspects of quality assurance in chemical analysis. This book is described as containing the lectures presented at the Fifth International Symposium on the Harmonization of Internal Quality Assurance Schemes for Analytical Laboratories held in Washington, DC, July 1993. It was printed and circulated in advance of that symposium and the twenty papers, in an assortment of typefaces, appear to be pre-prints submitted by the authors.Only 10 of the 20 papers in this book relate to internal quality assurance schemes; the others are about inter-laboratory trials, interna- tional surveys, reference materials and the quality of analy- tical results in general. Some of the papers are brief (3 or 4 pages), and appear to be abbreviated versions of the lectures. Others are quite detailed and are up to 20 pages long; the latter appear to supplement what were possibly shorter talks. There is no account of any discussion having taken place after the reading of any of these lectures. Over the past 10 years, Honvitz and his co-workers have published a valuable series of papers on the precision to be expected for a wide range of methods.In this book, Horwitz and Albert suggest revisions to the IUPAC 1987 Harmonized Protocol for Method Performance Studies and make propo- sals for the applications of performance criteria to internal quality control systems. ‘This book does not provide a complete guide to the setting up of a scheme of internal quality assurance for an analytical laboratory but will supplement the outlines indicated by accredi- tation bodies.’ Holcomb illustrates the manner in which a highly abbre- viated AOAC Official Method, intended for a graduate chemist, may be expanded to allow non-graduate technician to perform it in a reliable and reproducible manner. However, this paper should be read in conjunction with the remarks in the paper by Horowitz and Albert, who stress the effect that a series of minor changes in the analytical procedure may have on the overall performance of the method. Locke and Liabastre provide a comprehensive account of a scheme for the accreditation of laboratories associated with the determination of lead in environmental samples. The principles could be adapted to suit laboratories engaged in other fields of activity. Dabeka and Hayward suggest procedures to detect and correct for adventitious contamination when working near the level of detection for a method. De Boroviczkny, in the context of the medical laboratory, outlines the actions to be taken when results are obtained that indicate either a statistically extreme value or a critical clinical condition. For a book on quality assurance, this has the appearance of having been compiled in a hurry without adequate checking. There is inconsistency in the manner in which literature references are cited and minor errors were noticed in the references to some of the more readily available publications. Reference 13 on page 150 is incorrect. Two small misprints were noticed. This book does not provide a complete guide to the setting up of a scheme of internal quality assurance for an analytical laboratory but is a useful introduction to the subject and will supplement the outlines indicated by accreditation bodies. A. H . Latimer

ISSN:0003-2654    

DOI:10.1039/AN994190041N

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, April 1994, Vol. 11 9 45N Conference Diary Date 1994 May 7-12 8-12 8-13 8-13 9-13 16-19 16-20 16-20 23-25 24-27 24-27 29-116 30-216 30-116 June 1-3 1-3 Conference Location Contact Food Structure Annual Meeting 85th AOCS Annual Meeting & Expo HPLC ’94, Eighteenth International Symposium on Column Liquid Chromatography CLEO ’94: Conference on Lasers and Electro-Optics Focus 94-The Annual National Meeting and Exhibition of the Association of Clinical Biochemists 24th Annual Symposium on Environmental Analytical Chemistry Deauville Conference: 13th International Symposium on Microchemical Techniques; 2nd Symposium on Analytical Sciences 24th International IAEAC Symposium on Environmental Analytical Chemistry ISPAC 7: International Symposium on Polymer Analysis and Characterization 3rd Symposium on Molecular Chirality International Symposium on Metals and Genetics: Toxic Metal Compounds in Environment and Life 5; Interrelation between Chemistry and Biology 42nd ASMS Conference on Mass Spectroscopy 14th Nordic Atomic Spectroscopy and Trace Analysis Conference Scandinavian Symposium on Infrared and Raman Spectroscopy Toronto, Ontario, Canada Atlanta, GA, USA Minneapolis, MN, USA Anaheim, CA, USA Brighton, UK 0 t tawa , Canada Montreux, Switzerland Ottawa, Ontario, Canada Les Diablerets, Switzerland Kyoto, Japan Toronto, Ontario, Canada Chicago, IL, USA Naantali, Finland Bergen, Norway Dr.Om Johari,, SMI, Chicago (AMF O’Hare), Tel: + 1 708 529 6677. Fax: + 1 708 980 6698 AOCS EducatiodMeetings Department, P. 0. Box 3489, Champaign, IL 61826-3489, USA Tel: +1 217 359 2344.Fax: +1217 351 8091 Ms. J. E. Cunningham, Barr Enterprises, P.O. Box 279, Walkersville, MD 21793, USA Tel: +1301898 3772. Fax: +1301898 5596 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC 20036-1023, USA Tel: +1 202 223 9034. Fax: +1202 416 6100 Focus 94, P.O. Box 227, Buckingham, Buckinghamshire, UK MK18 5PN Tel: +44 2806 613. Fax: +44 2806 487 Dr. M. Malaiyandi, CAEC, Chemistry Department, Carleton University, 1255 Colonel By Drive, Ottawa, Canada KlS5B6 Tel: + 1 613 788 3841. Fax: + 1 613 788 3749 D’Conference 94, 7 rue d’Argout, 75002 Paris, France Tel: +33 1 42 33 47 66. Fax: +33 140 41 92 41 Dr. James F. Lawrence, Food Additives and Contaminants, Health and Welfare, Tunney’s Pasture, Ottawa, Ontario, Canada K1A OL2 SecrGtariat, ISPAC 7, CERMAV-CNRS, BP 53 X, 38041 Grenoble Cedex, France Professor Terumichi Nakagawa, Symposium on Molecular Chirality (SMC), Faculty of Pharmaceutical Sciences, Kyoto University, Yoshida-Shimoadachi-cho, Sakyo-ku, 606 Japan Fax: +8148 471 0310 (Professor Hara) Professor B.Sarkar, Department of Biochemistry, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1x8 ASMS, 815 Don Gaspar, Santa Fe, NM 87501, USA Tel: + 1 505 989 4517. Ari Ivaska, Abo Akademi University, Laboratory of Analytical Chemistry, Biskopsgatan 8, SF-20500 Abo Turku, Finland Dr. Alfred Christy, Department of Chemistry, University of Bergen, N-5007 Bergen, Norway IL 60666-0507, USA Second International Symposium on Bruges, Professor C.Van Peteghem, Symposium Hormone and Veterinary Drug Residue Analysis Belgium Chairman, Faculty of Pharmaceutical Sciences, University of Ghent, Harelbekestraat 72, B-9000 Ghent, Belgium Tel: +32 9 221 89 51 (ext. 235). Fax: +32 9 220 52 43 Kay Russell, Conference Department, Elsevier Banbury Road, Oxford, UK OX2 7DH Tel: +44 (0) 865 512242. Fax: +44 (0) 865 310981 Biosensors 94-The Third World Congress on New Orleans, Biosensors USA Advanced Technology, Mayfield House, 25646N Analyst, April 1994, Vol. 119 Conference Date 5-7 5-1 1 6-8 8-1 1 12-15 13-15 15-17 15-18 16-17 16-17 19-21 19-24 20-23 27-117 July 3-7 Location Bruges, Belgium Contact VIth International Symposium on Luminescence Spectrometry in Biomedical Analysis-Detection Techniques and Applications in Chromatography and Capillary Electrophoresis Professor Dr.Willy R. G. Baeyens, Symposium Chairman, University of Ghent, Pharmaceutical Institute, Dept. of Pharmaceutical Analysis, Lab. of Drug Quality Control, Harelbekestraat 72, B-9000 Ghent, Belgium Tel: +32 (0) 9 221 89 51. Fax: +32 (0) 9 221 41 75 Dechema, Theodor Heuss-Allee 25, P.O. Box 970146, D-W-6000 Frankfurt am Main 97, Germany A. Perratt, Los Alamos National Laboratory, Group X-10, MS D-406, P.O. Box 1663, Los Alamos, NM 87545, USA Professor M. ValcBrceVDr. M. D. Luque de Castro, (Flow Analysis VI), Departamento de Quimica Analitica, Facultad de Ciencias, E-14004 Cordoba, Spain Tel: +34 57 218616. Fax: +34 57 218606 Ms. Janet Cunningham, SymposiudExhibit Manager, Barr Enterprises, P.O.Box 279, Walkersville, MD 21793, USA Tel: +1301898 3772. Fax: +1301898 5596 Dr. Agneta Sjogren, The Swedish Chemical Society, Wallingatan 24, tr. S-111 24 Stockholm, Sweden Fax: +46 8 106 678 Joseph Geller, Geller Microanalytical, 1 Intercontiental Way, Peabody, MA 01960, USA Tel: +1 508 535 5595. The Second International Symposium on Speciation of Elements in Toxicology and in Environmental and Biological Sciences, Yngvar Thomassen, National Institute of Occupational Health, P.O. Box 8149 DEP, N-0033 Oslo 1, Norway Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5V7 Tel: +1 613 932 7702. Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5V7 Tel: +1 613 932 7702.Yngvar Thomassen, Trace Elements in Human Health and Disease, National Institute of Occupational Health, P.O. Box 8149 DEP, N-0033 Oslo, Norway Tel: 47 22466850. Fax: 47 22603276 Mrs J. A. Challis, Chromatographic Society, Suite 4, Clarendon Chambers, 32 Clarendon Street, Nottingham, UK NG1 5JD Tel: +44 602 500596. Fax: +44 602 500614 Dr. Art Springsteen, Labsphere Inc., P.O. Box 70, North Sutton, NH 03260, USA Tel: +1 603 927 4266. Professor Tim0 Korhonen, Biochemical Society, European Federation of Biochemical Societies (FEBS), Department of General Microbiology, University of Helsinki, Mannerheimintie 172, SF-00300 Helsinki, Finland 24th ACHEMA Frankfurt, Germany Conference on Plasma Science Santa Fe, NM, USA 6th International Conference on Flow Analysis Toledo, Spain 1994 PREP Symposium and Exhibit Washington, DC, USA 4th International Symposium on Field-Flow Fractionation Lund, Sweden 16th Symposium on Applied Surface Analysis (ASSD) Burlington, MA, USA The Second International Symposium on Speciation of Elements in Toxicology and Environmental and Biological Sciences Loen, Norway 14th International Symposium on Environmental Pollution Toronto, Canada Toronto, Canada Loen, Norway 18th International Conference on Analytical Chemistry and Applied Chromatograph y/Spectroscopy The 5th Nordic Symposium on Trace Elements in Human Health and Disease 20th International Symposium on Chromatography Bournemouth, UK 2nd Oxford Conference on Spectroscopy Ringe, NH, USA Special FEBS Meeting on Biological Membranes Espoo, Suomi-Finland Mrs.Gerrie Westerlaken, Conference Organizing Bureau VNW, Postbus 1558,6501 BN Nijmegen, The Netherlands Tel: +31 80 234471. Fax: +3180 601159 International Chemometrics Research Meeting Veldhoven (Eindhoven), The NetherlandsAnalyst, April 1994, Vol. 119 47N Date Conference Location 18-22 XI11 International Congress on Electron Paris, Microscopy France 20-22 Seventh Biennial National Atomic Hull, Spectroscopy Symposium UK August 2-6 8-10 8-12 14-18 21-26 24-26 28-219 29-219 The Second Changchun International Changchun, Symposium on Analytical Chemistry(C1SAC) China 40th Canadian Spectroscopy Conference Halifax, Canada IGARSS '94: 1994 International Geoscience and Remote Sensing Symposium USA Pasadena, CA, International Symposium on Bacterial Montreal, Polyhydroxyalkanotes (ISBP '94) Quebec, Canada 208th ACS National Meeting (with Sessions of Washington, Chemistry, Chemical Health and Safety, etc ) USA Analytical Chemistry, Environmental DC, International Symposium on Capillary Electrophoresis CLEOLEUROPE-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 7th International Symposium on Synthetic Membranes in Science and Industry RSC Autumn Meeting (with Analytical Session on Analytical Challenges in Toxicology and Pollution) 11-16 EUCMOS XXII: XXIInd European Congress on Molecular Spectroscopy Heslington, York, UK Amsterdam, Holland Budapest, Hungary Warsaw, Poland Coimbra , Portugal Tubingen, Germany Glasgow , UK Essen, Germany Contact B.Jouffrey, SFME 67, rue Maurice Gunsbourg, 94205, Ivry sur Seine cedex, France Tel: +33 1 46702844. Fax: +33 1 46708846 Dr. Steve Hill, Department of Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, UK PL4 8AA 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: +(902) 420 0203. Fax: +(902) 420 8612 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 ISBP Secretariat, Conference Office, McGill University, 550 Sherbrooke St. West, West Tower, Suite 490, Montreal, Quebec, Canada H3A 1R9 Tel: +1514 398 3770. Fax: +1 514 398 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: Direct line: 0904 432576 General Office: 0904 432511. Fax: +0904 432516 Meetings and Conference Department, The Institute of Physics, 47 Belgrave Square, London, UK SWlX 8QX Tel: +44 71 235 6111. Fax: +44 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) 22 59 96 Profa. Dra. Ana Maria Oliveira Brett, Departamento de Quimica, Universidade de Coimbra, 3049 Coimbra, Portugal Tel: +351 39 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 71 437 8656. Fax: +44 71 734 1227 GDCh-Geschiiftsstelle, Abt. Tagungen, Varrentrappestr. 40-42, Postfach 90 04 40, D- 60oO Frankfurt am Main 90, Germany Tel: +49 69 79 17 358. Fax: +49 69 79 17 47548N Analyst, April 1994, Vol. 11 9 Date 12-15 12-15 13-18 18-22 19-21 19-21 19-23 21-23 21-23 22-24 25-28 25-30 26-28 26-30 29-30 Conference Locat ion Separations for Biotechnology 3rd International Symposium on Environmental Geochemistry Reading, UK Krakow, Poland 3rd International Symposium on Mass Spectrometry in the Health and Life Sciences Geoanalysis 94: An International Symposium on the Analysis of Geological and Environmental Materials San Francisco, CA, USA Ambleside, UK The Second International Conference on Applications of Magnetic Resonance in Food Science The Fourth Annual CIM Field Conference Aveiro, Portugal Sudbury, Ontario, Canada XIIIth International Symposium on Medicinal Pans, - - Chemistry 7th International Symposium on Environmental Radiochemical Analysis 5th International Symposium on Pharmaceutical and Biomedical Analysis 12th National Conference on Analytical Chemistry 5th International Symposium on Chiral Discrimination 1994 European Workshop in Chemometrics Protozoan Parasites and Water 16th International Symposium on Capillary Chromatography France Bournemouth, UK Stockholm, Sweden Constan ta, Romania Stockholm, Sweden Bristol, UK York, UK Riva del Garda, Italy Food and Feed Analysis: A Focus on Methods Nyon, with Mineral Hazards to Health and the Switzerland Environment Contact SCI Conference Office, 14/15 Belgrave Square, London, UK SWlX 8PS Tel: +44 71 235 3681.Fax: i-44 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 Marilyn Schwartz, Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 9413-0446, USA D.L. Miles, Analytical Geochemistry Group, British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, UK NG12 5GG Tel: +44 602 363100. Fax: +44 602 363200 Dr. A. M. Gil, Department of Chemistry, University of Aveiro, 3800 Aveiro, Portugal 1994 CIM Field Conference, c/o Sudbury Geological Discussion Group, P.O. Box 1233, Station B, Sudbury, Ontario, Canada P3E 4S7 CONVERGENCES/ISMC '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 LE11 3TU Tel: +44 509 222585 or +44 509 222545. Fax: +44 509 233163 Swedish Academy of Pharmaceutical Sciences, P.O.Box 1136, S-11181 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-11181 Stockholm, Sweden Tel: +46 8 245085. Fax: +46 8 205511 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 IFAB Communications, Institute for Applied Biology, University of York, York, UK YO1 5DD Tel: +44 (0)904 432940. Fax: +44 (0)904 432917 Professor Dr. P. Sandra, 1.0 .P.M.S., Kennedypark 20, B-8500 Kortrijk, Belgium Tel: +32 56 204960. Fax: +32 56 204859 T. Rihs, Swiss Federal Research Station for Animal Production, CH-1725 Posieux, Switzerland Tel: +4137 877 111.October 2-7 29th Annual Meeting of the Federation of Analytical Chemistry and Spectroscopy USA 0003, USA Societies Preparative and Industrial Chromatography Germany St. Louis, MO, FACSS, P.O. Box 278, Manhattan, KS 66502- Tel: + 1 301 846 4797. 3-6 PREP '94: 11th International Symposium on Baden-Baden, GDCh-Geschaftsstelle, Abt. Tagungen, Varrentrappestr. 40-42, Postfach 90 04 40, D- 6OOO Frankfurt am Main 90, Germany Tel: +49 69 79 17 358. Fax: +49 69 79 17 475Analyst, April 1994, Vol. 119 49N Conference Location Contact Date 17-19 30-411 1 31-211 1 3rd International Symposium on Supercritical Strasbourg, Fluids France OPTCON '94 Boston, MA, USA ANABIOTEC '94: 5th International Minneapolis, Symposium on Analytical Methods, Systems MN, and Strategies in Biotechnology USA November 6-12 Third Rio Symposium on Atomic Caracas, Spectrometry Venezuela 9-11 11th Montreux Symposium on Liquid Montreux , Chromatography-Mass Spectrometry (LC/ Switzerland MS; SFCMS; CEMS; MSMS) 10-11 17th International Conference on Chemistry, New Delhi, Bio Sciences, and Environmental Pollution 18-22 Joint Oil Analysis Program International Condition Monitoring Conference 24-26 Fifth International Symposium on Advances in Electrochemical Science and Technology 1995 January 8-13 1995 Winter Conference on Plasma Spectrochemistry February 19-24 OFC '95: Optical Fibre Communication Conference April 10-13 Annual Chemical Congress (with Analytical Session) May 7-1 1 Seventeenth International Symposium on Capillary Chromatography and Electrophoresis 21-26 CLEO '95: Conference on Lasers and Electro-Optics India Pensacola, FL, USA Madras, India Cambridge, UK San Diego, CA, USA Edinburgh, UK Wintergreen, Virginia, USA Baltimore, MD, USA 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: +1202 223 9034. Fax: +1202 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 938322157 19 134157633551962 1695 M. Frei-Hausler, Postfach 46, CH-4123 Allschwil 2, Switzerland Tel: +41614812789. Fax: +41614820805 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 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 420247 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC 20036-1023, USA Tel: +1202 223 9034. Fax: +1202 416 6100 Dr. J. F. Gibson, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 71 437 8656. Fax: +44 71 734 1227 Dr. Milton L. Lee, Department of Chemistry, Brigham Young University, Provo, UT 84602- 4672, USA Tel: + (801) 378-2135. Fax: + (801) 378-5474 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC 20036-1023, USA Tel: +1202 223 9034. Fax: +1 202 416 610050N Analyst, April 1994, VoE. 119 Date Conference Location Contact 21-26 QELS '95: Quantum Electronics and Laser Science Conference Baltimore, MD, 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 June 5-8 Fifth Symposium on our Environment and First Asia-Pacific Workshop on Pesticides Convention City, Singapore 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 July 9-15 SAC95 Hull, UK Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 71 437 8656. Fax: +44 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 10-13 Vth COMTOX Symposium on Toxicology and Clinical Chemistry of Metals Vancouver, British Columbia, Canada August 27-219 CSI XXIX: Colloquium Spectroscopicum Internationale Leipzig, Germany GDCh-Geschaftsstelle, Abt. Tagungen, Varrentrappestr. 40-42, Postfach 90 04 40, D- 60oO Frankfurt am Main 90, Germany Tel: +49 69 79 17 358/360/366. Fax: +49 69 79 17 475 September 6-8 5th Workshop on Chemistry and Fate of Modern Pesticides Paris, France Leuven, Belgium Professor M-C. Hennion, ESPCI, Labo. Chimie Analytique, 10 rue Vauquelin, 75005 Paris, France Professor J. Hoogmartens, Drug Analysis '95-Leuven, Institute of Pharmaceutical Sciences, Van Evenstraat 4, B-3000 Leuven, Belgium Tel: +32 16 28 34 40. Fax: +32 16 28 34 48 12-15 5th International Symposium on Drug Analysis November 5-10 1996 April 16-21 8-12 1-7 15-20 OPTCON '95 San Jose, CA, 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 HPLC '96: Twentieth International Symposium on High Performance Liquid Chromatography XVI International Congress of Clinical Chemistry San Francisco, CA, USA London, UK Mrs. Janet Cunningham, Barr Enterprises, P.O. Box 279, Walkersville, MD 21793, USA Tel: +1301898 3772. Fax: +1301898 5596 Mrs. Pat Nielsen, XVI International Congress of Clinical Chemistry, P.O. Box 227, Buckingham, UK MK18 5PN Fax: +44 280 6487 Professor Luigia Sabbatini, Euroanalysis IX, Dipartimento di Chimica, Universith di Bari, Via Orabona, 4, 70126 Bari, Italy Tel: +39 80 242020/16/14. Fax: +39 80 242026 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 Euroanalysis IX Bologna, Italy 21st International Symposium on Chromatography Stuttgart , Germany

ISSN:0003-2654    

DOI:10.1039/AN994190045N

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, April 1994, Vol. 119 51N Courses Date 1994 May 16-19 23-25 24-26 July 4-6 4-8 Conference Location Content Sally Stafford, Hewlett Packard, Little Falls Site, 2850 Centerville Road, Wilmington, DE 19808- 1610, USA Tel: +302 633 8444. Jim Alexander, Rohm and Haas Laboratories, 727 Norristown Road, Spring House, PA 19477, USA Tel: 2135 619 5226. Dr. Julian Tyson, Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA Tel: +(413) 545 0195. Fax: +(413) 545 4856/4490 Modern Practice of Gas Chromatography Short Course West Chester, PA, USA Fifteenth Annual Introductory HPLC Short course West Chester, PA, USA Fourth Annual Flow Injection Atomic Spectrometry Short Course Amherst, MA, USA Heslington, York, UK Dr. T. L. Threlfall, Industrial Liaison Executive, University of York, Department of Chemistry, Heslington, York, UK YO1 5DD Tel: Direct line: 0904 432576 General Office: 0904 432511.Fax: +0904 432516 Mrs. S. J. Maddison, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, UK LEll 3TU Tel: + (0509) 222575. Problem Solving for Analytical Leaders High Performance Liquid Chromatography Short Course Loughborough, Leicestershire, UK August 21-24 Capillary Electrophoresis Course Dr. T. L. Threlfall, Industrial Liaison Executive, University of York, Department of Chemistry, Heslington, York, UK YO1 5DD Tel: Direct line: 0904 432576 General Office: 0904 432511. Fax: +0904 432516 Heslington, York, UK September 4-8 Molecular Graphics and Modelling Short Course Heslington, York, UK Dr.T. L. Threlfall, Industrial Liaison Executive, University of York, Department of Chemistry, Heslington, York, UK YO1 5DD Tel: Direct line: 0904 432576 General Office: 0904 432511. Fax: +0904 432516 Mrs. S. J. Maddison, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, UK LEll 3TU Tel: +(0509) 222575. Mrs. Hilary L. Thackray, Department of Continuing Professional Education, Continuing Education Building, Springfield Mount, Leeds, UK LS2 9NG Tel: + (0532) 333233. 5-9 AA/ICP-AES-ICP-MS Short Course Loughborough, Leicestershire, UK 6-9 The Leeds Course in Clinical Nutrition Leeds , UK 13-14 Recent Advances in Thermal Analysis Techniques Horsforth, Leeds, Edward Charsley/Stephen Warrington, Thermal UK Analysis Consultancy Service, Leeds Metropolitan University, Calverley Street, Leeds, UK LS13HE December 15-17 Capillary Electrophoresis Short Course Loughborough, Mrs. S. J. Maddison, Department of Chemistry, Leicestershire, Loughborough University of Technology, UK Loughborough, Leicestershire, UK LEll 3TU Tel: + (0509) 222575. 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 4 W . Tel: +44 (0)223 420066. Fax: +44 (0)223 420247.

ISSN:0003-2654    

DOI:10.1039/AN994190051N

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

52N Analyst, April 1994, Vol. 119 Future Issues will lnclude- Determination of Malondialdehyde by High-performance Liquid Chromatography using 4-(2-Phthalimidyl)benzohy- drazide as Precolumn Fluorescent Labelling Reagent-Yasuto Tsuruta, Yuuko Date, Hiroshi Tonogaito, Narumi Sugihara, Koji Furuno and Kazuya Kohashi Electrocatalytic Oxidation and Flow Injection of Reduced Nicotinamide Coenzyme at a Glassy Carbon Electrode Modified by Polymer Thin-film-Shaojun Dong and Qijin Chi Sulfur(rv)/Cobalt(II)/Azide System and its Application to Investigate Sulfur Hexafluoride Decomposition under Elec- trical Discharges-D. Klockow, S. M. A. Segundo and E. A. Neves Derivatization of Organic Compounds Prior to Analysis via GC-IRMS Gas Chromatography Isotope Ratio Mass Spec- trome try-Gareth Rieley Two-dimensional Electrophoresis of Proteins with a Different Approach to Isoelectric Focusing-Meral Yucel, S.M. Saqlan Nagvi, V. Cengiz Ozalp and H. Avni Oktem Programmed Two-stage Flow Controller For Supercritical Fluid Chromatography-Donjin Pyo and Hideo Makishima Polarographic Behaviour and Determination of Ranitidine in Pharmaceutical Formulations and Urine-Pablo Richter, M. Ines Toral and Fernando Munoz-Vargas Application of Tryptamine as a Derivatizing Agent for Airborne Isocyanates Determination. Part 6. Confirmation of the Concept of Isolation of a Selected 11-System of a Derivative for Specific High-performance Liquid Chromato- graphy Detection Through Analysing Bulk Materials for Total Isocyanate Content-Weh S. Wu The Fountain Cell: a New Tool for Chemiluminescence Analysis by Flow Injection-Jaromir Ruzicka, Cy H.Pollema, D. J. Tucker, B. Toivola and G. D. Christian Selective Synchronous Spectrofluorimetric Detection of Ace- naphthene in Mixtures of Three-ring Aromatic Compounds Based on Complexation with P-Cyclodextrin in the Presence of Iodide Ion as Quencher-Masaki Tachibana and Motohisa Furusawa Rapid Fluorescence Flow-injection Immunoassay Using a Novel Perfusion Chromatographic Material-Derek A. Palmer, Mark Evans and James N. Miller Photoelectrochemistry With Quinone Radical Anions: Kine- tics of Homogenous Redox Catalysis-Brian R. Eggins and Peter K. J. Robertson Determination of Fenbendazole and Oxfendazole in Liver and Muscle Using Liquid Chromatography-Mass Spec- trometry-W. John Blanchflower, Andrew Cannavan and D.Glenn Kennedy Classification of Mineral Particles by Nonlinear Mapping of Electron Microprobe Energy Dispersive X-Ray Spectra- Rene Van Grieken, Boris Treiger, Igor Bondarenko, Piet Van Espen and Fred Adams Investigation of a Radioactive Particle and a Soil Sample Obtained From The Windscale Area in 1 9 5 H . R. Jones, A. W. McMahon, J. Toole and J. Gray Decentralized Electrochemical Monitoring of Trace Metals: From Disposable Strips to Remote Electrodes-Joseph Wang Selective Membranes for the Construction and Optimization of an Amperometric Oxalate Enzyme Electrode-+. M. Reddy, Seamus P. J. Higson, Ian Christie and P. Vadgama Raman Spectra and Analysis of Polynucleotides Containing Adenosine Residues-Pedro Carmona, Rosario Escobar, Marina Molina and Aurora Lasagabaster Determination of Impurities in Zirconium Disilicide and Zirconium Diboride by Indutively Coupled Plasma Atomic Emission Spectrometry-Fumiaki Yokota, Hisashi Morikawa and Toshio Ishizuka Direct Atomization Atomic Absorption Spectrometric Deter- mination of Be, Cr, Fe, Co, Ni, Cu, Cd and Pb in Water with Zirconium Hydroxide Coprecipitation-Toshihiro Nakam- ura, Hideyuki Oka and Mikita Ishii Quantification of Tiaprofenic Acid Using Voltammetric and Spectrophotometric Techniques-Azza M.M. Ali, Kamla M. Emara and Mahmoud Khodari Sorption of Aluminium on Tri-n-butyl Phosphate-Plasticized Polyurethane Foam Sorbents from Sodium Hydroxide Solu- tion: Application to the Determination of Aluminium in Glasses and Slags-S. K. Roy and J.K. Mondal Selectivity of Polymer-coated Alumina Stationary Phases for Reversed-phase Liquid Chromatography. Part 1. Methylene Group Selectivity-Joe P. Foley and Rene V. Arenas Spectrophotometric Determination of Carbon Tetrachloride Based on a Through Photoactivated Colour Reaction-Anjali Pal Flow Injection Analysis of Formaldehyde in Reagents and Beverages-Hironori Tsuchiya, Shigeru Ohtani, Kuniaki Yamada, Mioko Akagiri, Nobuhiko Takagi and Masaru Sat0 Optimization of the Experimental Parameters in the Determi- nation of Copper( 11) by Differential-pulse Anodic Stripping Voltammetry and Evaluation of the Characteristic Detection Curves-Ana Herrero. Ortiz M. Cruz, M. Julia Arcos and Jesus Lopez-Palacios Occurrence, Mechanism and Analytical Applications of Electrogenerated Chemiluminescence-Gillian M.Greenway and Andrew W. Knight Determination of Chromium (VI) In River Water Samples by Electrothermal Atomic Absorption Spectrometry-Ying-Sing Fung and Wing-Cheong Sham Direct Determination of Manganese in Sea-water by Elec- trothermal Atomic Absorption Spectrometry with Sodium Hydroxide as Chemical Modifier for Interference Removal- Chi-Ren Lan and Zeev B. Alfassi Spectrofluorimetry at Zero Angle: Determination of Salicylic Acid in Acetylsalicylic Acid Pharmaceutical Formation-Gio- vanni Puglishi, Antonino Villari, Norbert0 Micali and Mas- simo Fresta Differential-Pulse Cathodic Stripping Voltammetric Determi- nation of Sodium Nitroprusside at a Hanging Mercury Drop Electrode Aided by Copper(i1) and Poly-L-Lysine Modifica- tion-Arnold G.Fogg, Ramin Pirzad, Josino C. Moreira, Antonio 0. S. S. Rangel, Rosa M. Alonso and Tony E. Edmonds Determination of Vanadium in Clam Tissue (Citterea Sp.) by Normal-Phase High-performance Liquid Chromatography With N-Phenylbenzohydroxamic acid-Mercedes Sanchez, Gracia Bagur and D6mingo Gazquez Simultaneous Determination of Tin, Lead and Molybdenum by Differential-pulse Polarography-Guler Somer and Ali Arslantas Naphthalene Contamination of Sterilized Milk Drinks Con- tained in Low-density Polyethylene Bottles, Part l 4 i - W a h Lau and Siu-Kay Wong53N Analyst, April 1994, Vol. I I9 Cobalt Phthalocyanine Derivatives as Neutral Carriers for Nitrite-sensitive PVC Membrane Electrodes-Ru-Qin Yu, Jun-Zhong Li, Xiao-Chun Wu, Hui-Gai Lin and Ruo Yuan A Micelle-stabilized Room-temperature Phosphorimetric Procedure for the Evaluation of Naproxen and Propanolol in Pharmaceutical Preparations-M.C. Garcia-Alvarez-Coque, I. Rapado Martinez and R. M. Villanueva Camaiias Determination of Aluminium in Water by Flow Injection with Fluorimetric Detection by Using Salicylaldehyde Carbohy- drazone as Reagent in a Micellar Medium-J. M. Cano- Pavh, E. Crist6fol Alcaraz and F. Shchez Rojas Effect of Tartrate on Vanadium-catalysed Chlorpromazine- Bromate Redox Reaction and Its Application to the Determi- nation of Vanadium in Natural Waters-Susumu Kawakubo, Bing Liang, Masaaki Iwatsuki and Tsutomu Fukasawa High-performance Liquid Chromatographic Determination of Cobalt(i1) as the 2-(5-Bromo-2-pyridylazo)-5-diethylamino- phenol Chelate after Preconcentration with a Cation- exchange Resin-Nobuo Uehara, Asako Katamine and Yoshio Shijo Study of the Stability of Extractable Trace Metal Contents in a River Sediment Using Sequential Extraction-H.D. Fiedler, J. F. L6pez-Sanchez, P. H. Quevauviller, Allan M. Ure, H. Muntau, R. Rubio and G. Rauret Trace Metal Atomic Absorption Spectrometric Analysis Utilizing Sorbent Extraction on Polymeric-based Supports and Renewable Reagents-Herbert L. Lancaster, Graham D. Marshall, Encarnoccion R. Gonzalo, Jaromir Ruzicka and Gary D. Ghristian Anodic Stripping Voltammetry with Triton X-100-modified Mercury Film Electrode in Flow Injection Analysis-Hari Gunasingham and Ruelito R. Dalangin Glucose Oxidation at Ruthenium Dioxide Based Electrodes- Michael E.G. Lyons, Catherine A. Fitzgerald and Malcolm R. Smyth Data Enhancement in Adsorptive Stripping Voltammetry by the Application of Digital Signal Processing Techniques-A. Economou, P. R. Fielden, P. A. Gaydecki and A. J. Packham Development of an Optical Formaldehyde Sensor Based on the Use of Immobilized Pararosaniline-Mark E. J. Baker and Ramaier Narayanaswamy Adsorbent Tube Evaluation for the Preconcentration of Volatile Organic Compounds in Air for Analysis by Gas Chromatography-Mass Spectrometry-Carol A. McCaffrey, John Maclachlan and B. I. Brookes Electrochemistry of Waste Removal. A Review-J. O’M. Bockris, R. C. Bhardwaj and C. L. K. Tennakoon Advances in Scanning Electrochemical Microscopy-Meral Arca, Allen J. Bard, Benjamin R. Horrocks, Thomas C. Richards and David A.Treichel I 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.54N Analyst, April 1994, Vol. 119 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 to wards a unified 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 15 April 1994 15 May 1994 Deadline for registration at the discounted rate (A surcharge is payable for registrations received after this date) 30 June 1994 Mailing of joining instructions to those who have registered 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

ISSN:0003-2654    

DOI:10.1039/AN994190052N

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, April 1994, Vol. 119 481 Foreword XXVlll CSI, York, 29th June4th July, The XXVIII Colloquium Spectroscopicum Internationale (CSI) was the fourth to be held in Great Britain and, in keeping with the last British CSI in Cambridge, was organized by the Association of British Spectroscopists. This is a confederation of all the specialized spectroscopy groups in the UK, including groups of the Royal Society of Chemistry and the Institute of Physics. We acknowledge, gratefully, the support which we received from the RSC staff, particularly those associated with JAAS and The Analyst and from the lnstitute of Physics, but we did not use a permanent conference organization and relied heavily on volunteers. For various reasons, we adopted a slightly different timing to previous conferences.Delegates arrived on Tuesday evening, 29th June, and the working sessions began on Wednesday morning and ran until late Saturday afternoon; delegates then dispersed, or went on to the post-CSI symposia on the Sunday morning. Although there were some doubts expressed before the CSI, the arrangement worked well in practice, and was particularly appreciated by those whose flight tickets required a Saturday night stay in the United Kingdom. The recession and the plethora of conferences involving spectroscopy in 1993 took their toll, and there were rather fewer delegates than we had originally hoped for, although more than we, at one time, feared. Some 600 delegates were present, from about 45 countries; this included about 150 from the United Kingdom and 55 from Germany, the next largest group.We offered reduced registration fees to delegates from Eastern Europe and other less favoured areas and this increased their number; we also gratefully acknowledge funding from the Royal Society and from the International Science Foundation (‘The Soros Fund’) for 15 delegates from the former Soviet Union and the support given to individual delegates from various firms. Those from Eastern Europe greatly appreciated the chance to attend and made a significant contribution to the conference, although the arrangements for them did involve a great deal of time and effort. Dr. Yngvar Thomassen, Professor Alfred0 Sanz-Medel and Professor Sam Houk enjoying a drink at the reception at the Railway Museum The Central Hall at the University of York, where muny of the events of CSI ’93 were held The Organizing Committee had adopted the policy endor- sed by the National Delegates’ meeting some years ago, and tried to include all branches of analytical spectroscopy.However, the majority of the papers submitted were on atomic spectroscopy; at least two of the four parallel sessions were devoted to some aspect of atomic spectroscopy or ICP- MS and some of the lectures on molecular spectroscopy were poorly attended. As there are many conferences on molecular spectroscopy, on NMR and on organic mass spectrometry, it is open to debate whether this overall coverage should be maintained or whether the CSI should be a specialized atomic spectroscopy conference. However, about 60 papers were submitted for the CSI issue of The Analyst and about 105 papers for the CSI issue of JAAS (40 and 70 accepted, respectively), so there is clearly a case for maintaining the wide coverage.We requested all the plenary and invited lecturers to submit manuscripts of their papers; unfortunately a significant number felt unable to do so, but those invited plenary papers which have been published will be collected and sent as a single volume to all delegates when late submissions have been received. Apart from the 5 plenary and 28 invited, 92 contributed lectures were presented in the four parallel sessions, and there were about 300 posters. We had laid down a format for the abstracts, but the instructions were interpreted in so many ways that we decided to use a scanner to reproduce them in a common style.We achieved the common style, thanks to a great deal of effort at Loughborough University of Technol- ogy by Barry Sharp and his team; producing the abstract book involved a tremendous amount of work but indexing then became relatively easy. The exhibition involved some 40 firms, both large and small. It had to be spread over three sites in the University, but we have helped to make future exhibitions better! We expressed our strong support for a new exhibition facility being planned at the University; it was decided to go ahead with the plan, but only as soon as the XXVIII CSI was over! Preliminary work in the Physics Department started during CSI, and went into full gear as soon as we left. The new enlarged exhibition area has now been opened.482 Analyst, April 1994, Vol.119 Three CSI chairmen, from left to right: (the late) Professor Klaus Dittrich (1 995), Dr. Edward Steers (1 993) and Dr. Neil Barnett (1 997) We had full co-operation from the weather, dry and sunny throughout (typical English summer weather!), so we enjoyed the campus to the full, and the excursions for the accompany- ing persons had excellent conditions. One of the main social events was an organ and choir concert in York Minster on the Wednesday evening. Thursday afternoon was free, with a choice of visits to various stately homes and gardens, to the North Yorkshire Moors steam railway, to Bempton Cliffs and Flamborough Head, and to the Drax power station. The final social event on the Saturday evening was a visit to the National Railway Museum and everyone was impressed with the museum display.On the Thursday evening, a meeting was held under the aegis of the Association of British Spectroscopists to discuss closer collaboration between spectroscopists in Europe. The discussion, with about fifty participants, centred on three topics: ( i ) Formal collaboration, as arranged through IUPAC, national Chemical Societies etc., information should be published more widely; (ii) informal collaboration, names and addresses would be circulated to assist the exchange of information about meetings and methods; and (iii) technical collaboration, including financial resources and multi-labora- tory projects, outside the scope of the meeting, but would be encouraged by contacts made through ( i ) and (ii).The National Delegates’ meeting took place on the Friday afternoon. The principal business was the choice of location for the XXX CSI in 1997; there were two bids, Australia and the United States, and it was decided by two votes to hold the 1997 CSI in Melbourne, Australia. There were a number of pre- and post-symposia associated with the XXVIII CSI. One-day tutorial meetings on vapour generation and chemometrics were held on Tuesday 29th June. The 3rd Kingston Conference on Analytical Spectro- scopy in the Earth Sciences took place immediately prior to CSI. (Papers will appear in a special issue of Chemical Geology.) After the CSI, the post-symposium on Graphite Atomizer Techniques in Analytical Spectroscopy took place at the University of Durham, followed by a one day meeting on Trace Elements in Clinical Chemistry; the 5th Surrey Conference on Plasma Source Mass Spectrometry took place at Lumley Castle Hotel near Durham, whilst the post-sympo- sium on the Analytical Applications of Glow Discharges was held at the University of York.(Papers from these meetings will be found in the special CSI issue of JAAS.) Personally, I managed to get to very few of the lectures, but I felt that it was a very friendly and happy conference, and I think that most of the delegates gained the same impression. I am conscious of things that we could, and should, have done better, but it is easy to see the problems afterwards. I would like to take this opportunity of thanking all my colleagues on the Organizing Committee, particularly the Scientific and Exhibition Committees, the Secretary, Barry Sharp, with his team at Loughborough University of Technology who dealt with registrations and the Treasurer, Terry Threlfall, at the University of York.Our thanks are also due to the York University Conference Office and to Neil James there, who always responded promptly to our requests, reasonable and unreasonable. Some may recollect that the chairman-designate of the 1981 CSI died during the 1979 CSI in Cambridge; again a tragic event has befallen the chairman of the next CSI. His many friends and colleagues were shocked in December by the sudden death of Klaus Dittrich, chairman of the XXIX CSI Organizing Committee. Our deepest sympathy goes to Frau Dittrich and to the German spectroscopic community. The XXIX CSI will go ahead in Leipzig on the planned dates (August 27 to September 1, 1995). The position of chairman has been taken over by Professor Dr. Hubertus Nickel, of the Forschungszentrum Jiilich. We wish him and his colleagues every success, and look forward eagerly to the next CSI. Edward Steers Chairman* of the X X V I I I CSI Organizing Committee University of North London

ISSN:0003-2654    

DOI:10.1039/AN9941900481

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, April 1994, Vol. 119 483 Multidimensional Gas Chromatography- Infrared Spectrometry-Mass Spectrometry* Plenary Lecture Kevin A. Krock, N. Ragunathan, Christoph Klawun, Tania Sasaki and Charles L. Wilkinst Department of Chemistry, University of California, Riverside, C A 92521, USA Multidimensional gas chromatography coupled with multispectral detection was investigated for the analysis of complex mixtures. As a test of this new methodology, the essential oil of cascarilla bark was analysed by capillary gas chromatography using a combination of mass spectral and both vapour phase and matrix isolation infrared spectral detection. The separation of components in this complex essential oil was carried out using a multidimensional capillary gas chromatography system with parallel cryogenic traps interposed between the first and second separation stages.By employing a multiport valve and multiple traps, it was possible to analyse multiple heartcuts from a single first- stage separation or, alternatively, to concentrate minor components by means of multiple-injection procedures. It was also possible to perform iterative heartcut analysis employing multiple analytical columns with different polarities by sample looping. The instrumentation developed provides flexibility in choice of trapping-time intervals in order to improve dynamic range, reduces experimental time relative to that required with a single cryogenic trap, and facilitates parallel enrichment of minor components in different chromatographic segments. This separation strategy combined with three different modes of spectrometric detection facilitates comprehensive analysis of a complex mixture.In this study, vapour phase and matrix isolation infrared spectral analyses were compared, the advantages of parallel analytical columns for complex mixture analysis were assessed, and a method to fingerprint essential oils by enrichment of minor components was investigated. Keywords: Gas chromatograph y-in frared spectrometry-mass spectrometry; multidimensional gas chromatography; complex mixture analysis; essential oils Introduction Complete qualitative and quantitative analysis of complex mixtures is a long-standing problem. Fortunately, improve- ments in measurement technology, particularly those invol- ving coupled separations and spectroscopic systems suitable for such analytical applications, continue to evolve.1 One issue that it is necessary to address is the desirability of providing whatever detector is used with pure substances, in order to avoid ambiguity o r error in subsequent computer-aided analysis. In that context, this paper describes a multidimen- sional gas chromatographic approach, implemented with two different gas chromatography-infrared spectrometry-mass spectrometry (GC-IR-MS) systems, which greatly improves Plenary lecture. presented at the XXVlIl Colloquium Spectroscopicum lnternationale (CSI), York, UK, June 29-July 4. 1993. J To whom correspondence should be addressed. the prospects for analysis of complex mixtures. Although described here for a complex natural product mixture, the approach is general and could also be useful for analysis of environmental, petroleum, or other multicomponent volatile mixtures.Although accepted techniques such as GC-MS and GC-IR can be used for such applications, the use of these methods separately for extensive mixture analysis is time- consuming and often does not provide definitive analytical data. Although the utility of GC-IR-MS2-7 has been documented for the analysis of complex mixtures, improved separation methods would make it more useful. This paper focuses on the implementation of an analytical paradigm combining multi- dimensional gas chromatography (MDGC) with two different types of GC-IR-MS systems utilizing intermediate parallel cryogenic trapping. In its simplest form, a MDGC experiment involves isolation of the components contained in a small segment or segments of a complex chromatogram generated by a first-stage gas chromatographic column (the precolumn) in an intermediate cryogenic trap and, subsequently, separa- tion of the trapped chromatographic effluents using a second chromatographic column (the analytical column) of different selectivity from the precolumn.8 For even a moderately complex mixture, such a strategy is necessary, because theory has shown that, for a single separation dimension, resolved peaks will occupy only 37% of a given column capacity, and that only 18% of that total capacity will be occupied by single- component peaks.9 Equally significant, recent simulation studies suggest that the capacity of the second dimension of a two-dimensional separation need not be very large to obtain a high-resolution separation. 10 A number of previous reports demonstrated the potential of MDGC for the analysis of complex mixturesl l-14.However, implementation of MDGC using a single, intermediate cryogenic trap strategy has some disadvantages. First, it requires n sequential injections in order to trap n sequential heartcuts, with each injection and trapping followed by second-stage analysis of the particular heartcut. Hence the analysis time is extended by a factor nt, where t is the time to inject, trap, and analyse any one of the n heartcuts. A second disadvantage is that the method does not provide a means for parallel enrichment of more than one minor component at a time from different segments of a complex chromatogram, where minor component samples from multiple injections are combined. Finally, a single-trap method makes it inconve- nient or impossible to carry out multiple-column multidimen- sional separations (GCtl) via sample looping or recycling.These shortcomings of single cryogenic trap MDGC systems prompted development of multiple, parallel intermediate cryogenic trapping as an additional tool to analyse complex mixtures. I3-l4 The results presented here demonstrate the advantages of such an approach.484 Analyst, April 1994, Vol. 11 9 Concept of Parallel Cryogenic Trapping Fig. 1 depicts a parallel cryogenic trapping experiment. In this hypothetical separation, six different portions of the primary column chromatogram, each corresponding to the com- ponents eluting in two or three chromatographic peaks are trapped.Subsequently, the contents of each trap are injected sequentially into an analytical column with different separa- tion characteristics from that of the primary column, resulting in the six second-stage chromatograms shown on the left (Fig. 1). Typically, more peaks will appear in the secondary chromatogram than in the first. Because the secondary analysis is carried out sequentially, it is clear that different analytical columns could be used for each of the six trapped samples, provided that suitable valves and switching were employed. Higher second-stage resolution can often be achieved by shortening the heartcut times for trapping ( e . g . , trap 10 to 20 s segments to trap fewer mixture components in each trap, or 1 to 3 min segments to trap more components).Shorter cut time intervals will result in improved component resolution in the secondary separations due to a reduction in the number of components injected into the second-stage column, with increased likelihood of successful separation of the components. As already mentioned, an additional advan- tage of a parallel-trapping system for the enrichment of minor components is that different segments of the precolumn chromatogram can be enriched simultaneously and then the components separated by multidimensional chromatography. Further, additional stages of GC analysis beyond the two shown in Fig. 1 (GCn) could be used. Hence, using GC’l, the enriched sections could be analysed with a variety of parallel analytical columns following a single enrichment step to improve the over-all separation and identification capacity.The obvious outcome of this procedure is that a considerable amount of time can be saved in the analysis of minor components in a complex mixture. Regarding information, each column used will provide an additional retention time parameter for each separated mixture component. For routine MDGC analysis, the GCfl technique will allow a large number of iterations for a given heartcut section through the use of a variety of parallel analytical columns. For example, it is possible to re-trap the effluent emerging from the Fourier transform infrared (FTIR) lightpipe. This can be done because the IR measurement is a non-destructive process.Samples from the precolumn or analytical columns are split in parallel to the IR and MS detectors (with the greatest percentage of the sample in each instance routed to Fig. 1 sional GC utilizing parallel cryogenic traps Schematic diagram illustrating the concept of multidimen- the IR detector) and the portion analysed by the IR detector is recycled for further evaluation. Thus, significant reductions in time for complex mixture analysis can be achieved, permitting spectrometric measurements of a chosen chromatographic segment many times over, with separations carried out in columns of different selectivity. The recycling technique demonstrated in this paper is significantly different from that previously demonstrated by Jennings et al.15 Although the approaches are similar, here, each chromatographic stage can be monitored by both IR and MS. However, the recycling experiment mentioned is limited to lightpipe-based GC-IR- MS or GC-IR systems. For cryogenic sample trapping GC-IR interfaces (i.e., where the infrared sample is deposited on a cooled surface for subsequent IR analysis), it is necessary to modify the experimental protocol to implement the same analysis logic discussed for lightpipe systems. This paper describes mu1 tidimensional GC-IR-MS results obtained with both lightpipe and cryogenic trapping GC-IR interfaces. First, MDGC results obtained using six parallel cryogenic traps with a Hewlett-Packard gas chromatography- infrared detector-mass-selective detector (GC-IRD-MSD) are discussed. In addition, MDGC results obtained using two parallel traps in conjunction with a GC-matrix isolation (M1)IR-MSD system are reported.For both systems, analysis of the complex essential oil derived from cascarilla bark oil serves to characterize performance. For the GC-MIIR-MSD system, programming of the GC-IR cryogenic trapping disc is used to enhance chromatographic separations, prior to IR measurements. The details of disc-speed programming are discussed elsewhere. 16 For cascarilla bark oil analysis, the emphasis in this paper is enrichment and identification of some of the minor com- ponents of this complex mixture, which consists primarily of various terpenes and their derivatives. A significant difficulty in the analysis of such multicomponent mixtures is separation and identification of minor components.This is particularly true for flavour and fragrance analysis applications, where both minor and major components may contribute equally to the organoleptic responses. 17-19 Unlike unleaded petrol, which was used in initial studies of parallel cryogenic trapping MDGC,13-*4 cascarilla bark oil has components of greatly differing polarity. Because the parallel cryogenic trapping system is a valve-based system, it is essential to evaluate it by using a sample with components representative of a wide range of polarities, in order to evaluate whether there is sample adsorption or peak broadening due to the sample coming into contact with the valves. There have been several previous reports on this issue, but results regarding possible difficulties with mechanical valves are inconclusive.20,21 In order to minimize the possible effects a valve may have on chromatographic performance, the systems used in the present study have valves located either after the detector or at the top of a chromatographic column.This design ensures that the valves are not subject to different temperature programming than that used in the separation, and reduces the possibility of peak broadening. However, possible effects on sample adsorption are not known. Experimental GC-IRD-MSD Equipment The parallel cryogenic trap system was designed as an addition to a standard Hewlett-Packard HP, Avondale, PA, USA) 5890 Series I1 gas chromatograph; the detectors used were an HP 5965B infrared detector (IRD) and an HP 5970B mass- selective detector.The detectors were configured in a parallel arrangement with a splitter routing approximately 90% of the analyte to the IRD and the remaining 10% to the MSD. TheAnalyst, April 1994, Vol. 119 485 conditions used for spectral acquisition from these two detectors are described elsewhere. *3-14 Fig. 2 is a schematic diagram of this multidimensional analysis system. Two six-port rotary selection valves (D) with one common input line and six individual output lines (Rheodyne, Cotati, CA, USA; maximum temperature, 300 "C) were used to feed and re-inject analyte from each individual trap. Each of the six traps were formed by enclosing a length of 1 .O pm film thickness MTX-5 steel capillary column (Restek, Bellefonte, PA, USA; maximum temperature, 350 "C) in a 45 cm long U-shaped 1/8 in diameter stainless-steel tube coated with polyimide.The total length of the internal capillary trapping column utilized for cryogenic trapping was 10 cm. For trapping, liquid nitrogen is allowed to flow through the 1/8 in steel tubes, with the flow being controlled by quick acting toggle valves (Supelco, Bellefonte, PA, USA). In addition to the two six-port valves, two four-port (V1 and V3) and a three-port rotary valve (V2) (Valco, Houston, TX, USA; maximum temperature, 300 "C) were also used. Valve Positions for Various Operational Modes Fig. 3[(a)-(d)] shows a series of schematic diagrams depicting the various valve positions. In each instance, valve V1 serves to select either venting or trapping of pre- or analytical column effluents.Fig. 3(a) shows the standard precolumn separation and detection arrangement. At the appropriate times, the segment(s) chosen for trapping is (are) directed into the traps by switching valve V1 from the vent (V) to the trap (T) position [Fig. 3(b)], and the six-port valves are used to select one of the six traps. During the trapping sequence, one can trap all the effluents into a single trap or trap different segments of the precolumn or analytical chromatogram in different traps. When the system is in either the pre- or analytical column trapping mode, valve V2 is in the vent position [Fig. 3(b) and ( d ) , and when valve V1 is in vent mode, valve V2 is directed towards one of the analytical columns [Fig. 3(c)].Fig. 3(c) shows the arrangement for re-injection of the trapped effluents onto one of the analytical columns. In the system described here, valve V3 was used to select which of the analytical columns would receive the chosen trap output. During this part of the analysis, valve V1 was directed -l- -@- Vent Fig. 2 Schematic diagram of the multidimensional GC-IRD-MSD system. A, Injector port; B, Rt,-1701 precolumn; C, make-up He for re-injection; D, trap-selection rotary valve; E, cryogenic traps; F, make-up flow for the analytical columns; G, Rt,-5 column; H, Stabilwax column: V1 cryogenic trap-switching valve: V2, post-trap vent-column-switching valve. and V3, analytical column selection valve towards the vent and valve V2 towards valve V3. A helium make-up gas flow (MA) forces the effluents from the trap and into the chosen analytical column.In this situation a second make-up gas flow (MB) and the precolumn head pressure (injection port, I) are maintained at low flow rates for normal analyses. Finally, Fig. 3(d) shows the valve arrangement for sample-looping capability. Here, helium make-up gas sweeps the analytical column effluents back to the cryogenic traps after passing through the IR detector. The presence of six-port rotary valves (T in Fig. 3) interposed between the traps and the analytical column serves two purposes. First, it obviates the necessity of using a number of glass Press-Tight connectors and therefore simplifies the plumbing, and second, it simplifies the re-injection process. Injection of trapped heartcuts onto an analytical column is carried out by selecting an unfilled trap to use as a trap bypass, turning off the liquid N2 to the chosen trap, and then waiting for the trap to equilibrate to the external oven temperature, which is maintained at 250 "C.Other valves are set to route the trap effluent to the chosen analytical column and the output valve of which is opened following warming of the trap. During warming, the rotary valves must be positioned to a trap not used for collecting eluents from the precolumn in order to establish the analytical column pressure and complete sample trapping. The advantage of the oven-heating tech- nique is that re-injection takes place instantaneously once a trapped valve position is selected. GC-MIFTIR-MSD System In addition to the IR and MS detectors, a flame ionization detector (FID) was available.An HP 5970B mass-selective detector was employed for MS detection, and a Mattson 4800 Cryolect matrix isolation FTIR spectrometer (Mattson, Madi- son, WI, USA) was used for IR detection. A Hewlett-Packard 5890A gas chromatograph was used for separations. Effluents from the columns were split 10% to the FID and 45% each to the IR and MS detectors, respectively. Injection of the cascarilla oil was carried out in the splitless mode (0.25 pl for enrichment measurements). The effluents to the Mattson Cryolect 4800 were mixed with a 5% argon-95% helium mixture in an open split interface, and were transferred to the Cryolect using a 200 pm i.d. fused silica capillary maintained at 250 "C.The cryodisc temperature during deposition and MA V Fig. 3 Switching scheme used for (a) precolumn chromatography, (b) trapping segments from the precolumn chromatogram, ( c ) re- injection of the trapped effluents, and (d) re-trapping all or part of the effluents re-injected in the previous step. I, Injection port; V, vent; MA, make-up gas flow A; MB, make-up gas flow B; T, cryogenic trap; and IRD, Hewlett-Packard IR detector486 Analyst, April 1994, Vol. 119 spectral measurements was maintained at 12 K. Each spec- trum was the average of 128 scans at a mirror velocity of 2.53 cm s-l and a resolution of 4 cm-l. Spectra were collected at the end of each chromatographic run, after deposition of the effluents on the cryodisc. Manipulation of the speed to control peak resolution in the Cryolect was carried out as described in a previous paper,l6 using a dedicated computer to control the cryodisc speed directly.This procedure allows changes in the deposition speed within a given chromatographic run. The MDGC modification to the GC-MIFTIR-MSD system is similar to that of the dual parallel cryogenic trap system previously described. 13 The MDGC system has two parallel cryogenic traps. The traps are enclosed in 1/16 in steel tubes. The actual trapping occurs in a 10 cm long 0.32 mm i.d. DB-5 capillary column with 1.0 pm film thickness (J & W Scientific, Folsom, CA, USA). Each of the traps is selected by an odoff valve preceding the trap (SGE, Austin, TX, USA). Placement of odoff valves before the traps prevents peak broadening of the chromatographic peaks in the analytical column separa- tion.Further, connections after the traps are made with glass press-tight connectors to minimize sample adsorption and peak broadening. A make-up gas line is used to ensure flow through the analytical column when separations take place in the precolumn. A four-port two-way rotary valve (Valco, TX, USA; maximum temperature 300 "C) is used for switching the precolumn effluents to the cryogenic traps. Re-injection of trapped analyte is carried out by switching the precolumn flow through the traps and warming the selected trap by means of a heater placed in the external oven. The heater maintains a temperature of 200 "C within the external oven at all times. Chromatography GC-IR D-MSD A 30 m x 0.32 mm i.d.Rt,-1701 (1.0 pm film thickness, Restek) column was used as the precolumn and 30 m x 0.32 mm i.d. Rt,-5 and Stabilwax (1.0 pm film thicknesses) columns were used as the two analytical columns (Restek). Helium ultra-high purity (UHP, 99.999% pure) was used as the mobile phase with a head pressure of 90 kPa for the precolumn and analytical column separations. This head pressure provided a linear flow velocity of about 33 cm s- l . GC-MIFTIR-MSD A 30 m x 0.32 mm DB-1701 column (1.0 pm film thickness, J & W Scientific) was used as the precolumn. The analytical column was 30 m x 0.32 mm DB Wax column (1.0 pm film thickness, J & W Scientific). Helium (UHP, 99.999% pure) was used as the mobile phase with a head pressure of 90 kPa for the precolumn and analytical column separations. This head pressure provided a linear flow velocity of about 33 cm s-1. Results and Discussion Cascarilla oil was analysed using parallel trapping multidimen- sional GC and two different GC-IR-MS analytical systems, as described under Experimental.For clarity, the results obtained with each of the analytical systems will be discussed separately. GC-IRLI-MSD Analysis Fig. 4 shows the precolumn chromatogram of the cascarilla oil separation carried out using a Rt,-1701 mid-polar column with a 0.05 p1 splitless injection. At least 85 peaks are clearly evident. To demonstrate the advantages of the sample-enrich- ment methods available with the system, three groups of minor components were selected for concentration and qualitative analysis.These portions of the original chromato- gram eluted between 15.5 and 18.5 min, 19.0 and 21.4 min, and 23.0 and 26.2 min. The enrichments were accomplished by sequentially injecting 0.25 pl of cascarilla oil samples twice and trapping each of the three selected heartcuts in a different trap. Because a 0.25 pl sample injection overloads the precolumn, it was of interest to determine the effect of sample injection size on the second stage chromatographic perfor- mance. For this purpose, the following control experiments were performed, using only the third heartcut (the 23.0-26.2 min segment). Separate sets of injections (4 x 0.25 pl, 4 x 0.1 pl, and 2 x 0.05 p1) of cascarilla oil were used to evaluate the effects of injection size on second stage chromatographic performance.Hence, for each of the first two trials, the selected heartcut was trapped after each injection to yield a combined sample from four injections. In the third experi- ment, the combined sample from two injections was trapped. In each of the three trials, the concentrated, trapped materials were subjected to second-stage analysis using the Stabilwax analytical GC column. The results are shown in Fig. 5. Examination of these chromatograms shows that there is excellent agreement among the three and that there are only minor retention time differences. The largest discrepancies occur at early retention times and are very likely the result of differential carry-over of major components eluting just prior to the third heartcut region of the precolumn chromatogram.From the results shown, it is clear that the use of 0.25 1-11 injections does not have major deleterious effects on the second stage chromatographic separation or component- enrichment performance. Figs. 6-8 contain both the second stage Rt,-5 and the second stage Stabilwax chromatograms obtained following enrich- ment of each of the three chromatogram segments. The first re-injection of the trapped segments was onto the Stabilwax column. The effluents emerging after that chromatographic separation were further trapped and subsequently re-injected onto the Rt,-5 column. It is clear that the Stabilwax analytical column separated the components in the enriched segments over a wider time range than the Rt,-5 column (i.e., the components were better retained on the Stabilwax column).This is a result of the presence of polar components in each of the three heartcuts chosen for concentration and further analysis. 10 15 20 25 30 35 40 45 50 55 Time/min Fig. 4 Precolumn chromatogram of 0.05 p1 of cascarilla bark oilAnalyst, April 1994, Vol. 119 487 It can also be seen from Figs. 6-8 that the signal-to-noise ratio for the pairs of chromatograms for each of the chosen heartcuts is similar. This suggests that sample looping did not result in major sample loss. An obvious conclusion is that heartcuts of heartcuts (GC3) could be analysed using this technique. Because about 10% of the sample is directed to the destructive MS detector at each stage of chromatographic analysis, one might expect that 90% of the sample should remain to be re-analysed after each stage of chromatographic analysis.If there were such efficient sample retention, it would be predicted that as many as 5-10 individual stages of chromatography, following a single sample injection, might be possible. In fact, the qualitative observations made during the present investigation indicate that approximately 25% of the sample, rather than the 10% directed to the MS, is lost during a single looping stage. Therefore, about four or five chromato- graphic stages for a single sample injection might be more realistic. Note that the present study does verify that at least I I I I I A d I 1 I I I ' 4-4- 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Timdmin three stages are possible. However, a more quantitative investigation of the efficiency of the sample-looping scheme is needed, as well as some examination of the causes of sample loss, before the realistic limits can be determined.The chromatograms shown in Fig. 6 each reveal the presence of 27 or more components [in contrast to the four or five peaks seen in the corresponding region of the original precolumn chromatogram (Fig. 4)) Similarly, Figs. 7 and 8 show chromatograms with significantly larger numbers of peaks than evident in the original precolumn separation, verifying that the initial separations of these minor com- ponents were incomplete. Although these two regions of the first-stage chromatogram contained between seven and ten peaks, the second heartcut chromatograms (Fig. 7) reveal the presence of at least 35 components and the third heartcut chromatograms (Fig.8) over 30 components. Table 1 sum- marizes the qualitative IR and mass spectrometric analysis of the major peaks in each of the three heartcuts. These results, which demonstrate the feasibility of GCn via sample looping through the lightpipe IRD provide good evidence of the analytical utility of the parallel cryogenic trapping system developed. An important design feature is the ll Fig. 5 Results of experiments of varying initial injection size and numbers of injections for minor component enrichment. Heartcut 3 (23-26.2 min) was selected, and second stage analysis was performed using the Stabilwax analytical column. Injections of cascarilla bark oil: (a) 4 x 0.25 yl; (b) 4 x 0.1 yl and (c) 2 x 0.05 pl 8 10 12 14 16 18 20 Fig.6 (a) Heartcut 1 (15.5-18.5 min) separated on the Stabilwax column (polar); and (b) heartcut 1 separated on the Rt,-5 (non-polar) analytical column. Peaks are identified in Table 1 Time/min 10 12 14 16 18 20 22 24 Time/min Fig. 7 (a) Heartcut 2 (19.0-21.5 min) separated on the Stabilwax column; and (b) heartcut 2 separated on the Rt,-5 analytical column. Peaks are identified in Table 1 I I 12 14 16 18 20 22 24 26 28 30 Time/min Fig. 8 (a) Heartcut 3 (23.0-26.2 min) separated on the Stabilwax column; and (b) heartcut 3 separated on the Rt,-5 column. Peaks are identified in Table 1488 Analyst, April 1994, Vol. 119 placement of the detectors before the valves and cryogenic traps. This hrrangement minimizes peak-broadening effects and allows spectrometric measurement of the analytes imme- diately as they emerge from the respective pre- and analytical columns.Hence, following an initial single-stage analysis to identify chromatographic regions of interest, it is possible to obtain spectrometric and retention time data for each of the selected heartcuts on three columns with a single injection. GC-MIIR-MSD For evaluation of the potential of multidimensional GC- MIIR-MSD analysis, a heartcut corresponding to the third heartcut (the 23.0-26.2 min segment) in Fig. 4 was chosen for trapping and further analysis. Fig. 9 shows the FID and MIIR response of the analytical column chromatogram. During the deposition of the effluents on the IR cryodisc three different disc rotation speeds were used (135,270 or 405 steps s- l ) .The regions where various disc speeds were used are indicated in the IR chromatogram shown in Fig. 9(b). Clearly, in these regions, peaks that would otherwise have partially or totally overlapped are now separated to a large extent. Furthermore, the IR reconstructed chromatogram [Fig. 9(b)] is in excellent agreement with the FID chromatogram [Fig. 9(a)] (at least with respect to retention times). However, because the sensitivities of these two independent detectors are different, there are the expected differences in relative responses to various mixture components. A good example of the effect of differential component sensitivity is seen for peak 1 in Fig. 9(b) (p-isopropylbenzaldehyde). Although this substance appears only as an unresolved shoulder on the succeeding peak in the FID (Fig.9(a)] and the MS-reconstructed chromatogram [Fig. 9(c)], gives an excellent response in the IR chromatogram, because it contains a strongly absorbing carbonyl group. Furthermore, the material eluting immediately afterwards happens to be a weak IR absorber, enhancing detection of the aldehyde in the particular mixture being separated. These results demonstrate that the use of parallel cryogenic GC sample trapping combined with lower temperature IR sample trapping using a speed programmed cryo-disc can confer some of the same advantages to the GC-MIIR-MSD analysis as demonstrated for the lightpipe-based system. Because of the significantly different manner with which IR spectra are measured with GC-IRD-MS and GC-MIIR- MSD instruments, sample looping is inherently more compli- cated for the matrix isolation (or any cryogenic direct IR sample deposition) system.As noted earlier, the flow IRD approach is easily adapted to sample looping. However, for IR trapping approaches, there is no convenient way to re-use samples that have been frozen in place on the IR sample stage. It would be possible either to split the output from the analytical column into four outputs, ie., FID, IR trap, MS and GC traps, or to employ a split injection of the re-injected analytes from the GC traps, with a significant portion being re- trapped. In either instance, the precolumn i.d. would have to be larger than that used in the developed system, because all detectors in the GC-MIFTIR-MSD are (for purposes of sample looping) destructive. Furthermore, with such an instrument, during the heartcutting procedure one cannot obtain both chromatographic and spectrometric information about the precolumn effluents.Multispectral Data Analysis Regardless of the multispectral analysis instrumentation chosen, automated data analysis for qualitative identification remains a major problem. A primary difficulty is the limited availability of high quality evaluated computer-readable spectral libraries of gas phase and matrix-isolated IR spectra and mass spectra. The National Institute of Standards and Technology (NIST) has a high quality mass spectral library. However, only about 800 of the approximately 42000 mass spectra in that library are pertinent to natural product analysis of the type described here.Similarly, relatively few of the 5000 spectra in the Mattson Cryolect matrix isolation IR spectral library are relevant to natural product analysis. Data analysis for the gas phase IR spectra used the 2000 spectra Hewlett- Packard gas phase IR Flavors and Fragrance library, with additional confirmation from the NIST mass spectral and Cryolect MIIR spectral libraries. Even with these database deficiencies, combined use of the complementary information available from IR and MS spectra greatly facilitate complete or partial structure elucidation of the components in complex mixtures. Regardless of the application area, it is clear that there is ample need for improved computer-readable spectral databases. Hence, an important goal as improved methods are sought for the analysis of complex mixtures should be the assembly of comprehensive, high quality libraries. These could serve as the basis for library-search approaches to complex mixture analysis and assist in the development of expert system based spectral interpretation algorithms.Conclusion We have described a multidimensional GC-multidimensional spectrometric method to analyse complex mixtures. The Table 1 Compounds identified by IR and MS Identified compounds Peak No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Fig. 6 Octanoic acid, 2-methyl, methyl ester Nonanone Alcohol Menthyl formate a-Thujone 6-Thujone Aldehyde Nonan-2-01 Alcohol Fig. 7 Sabenene y-Terpinene p-Cymene Terpinolene Straight chain ketone or-p-Dimethylstyrene Linalool oxide Alcohol Linalool oxide derivative Linalool Terpineol Alcohol Fenchyl alcohol Terpineol Alcohol Fig.8 or-Cubenene Germacrene-D Bornyl acetate Undecan-Zone Ester or ketone Myrtenal Unbellulone Livescone Borneo1 Nonan-2-01 y-Elemene Pipertol M yrtenol 1,2,4-TrimethoxybenzeneAnalyst, April 1994, Vol. 119 489 I 12 14 16 18 20 22 24 26 28 30 Retention timdmin Fig. 9 (a) FID trace of the secondary separation of heartcut 3 (23.0- 26.2 min.); (b) MIIR, and (c) MS reconstructed chromatograms obtained using the GC-MIIR-MSD instrument. Disc speeds used to achieve good chromatographic separation: A, 270; B, 135; C, 270; D , 135; E, 405; F, 270; and G , 135 steps s-l. 1, p-Isopropylbenzaldehyde unique ability to perform a GC3 experiment has been demonstrated, and it is predicted that the system developed could be used for multidimensional GC (GCn), where the dimension, n could be as great as 5 or 6.Because the design accommodates sample looping or recycling from a single primary column several times, more than two analytical columns can be used for the analysis of heartcuts chosen from initial separations of complex multicomponent mixtures. In addition? only a single enrichment step is required for the analysis in multiple analytical columns. Future work will include the development of computer-controlled techniques that will provide complete flexibility in the choice of columns to be used at any stage of multidimensional GC, with the possibility for dynamic programming of separation strategies. Another future direction will be the incorporation of high speed GC techniques for faster secondary separations employ- ing the Cryolect instrument, which incorporates variable speed deposition.Support from the National Science Foundation under Grant No. CHE-92-01277 and a grant from Imperial Chemical Industries are gratefully acknowledged. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 References Wilkins, C. L., Anal. Chem., 1987,59, 571A. Krock, K. A., and Wilkins, C. L., Anal. Chim. Acta, 1993,277, 381. Hembree, D. M., Smyrl, N. R., Davis, W. E., and Williams, D. M., Analyst, 1993, 118,249. Williams, D. T., Tran, Q., Fellin, P., and Brice, K. A., J. Chromatogr., 1991, 549,297. Hedges, L. M., and Wilkins, C. L., J. Chromatogr. Sci., 1991, 29, 345. Cooper, J . R., Bowater, I. C., and Wilkins, C. L., Anal. Chem., 1986, 58, 2791. Cooper, J. R . , and Wilkins, C. L., Anal. Chem., 1989,61,1571. Bertsch, W., in Chromatographic Science Series: Multidimen- sional Chromatography Techniques and Applications, ed. Cortes, H. J., Marcel Dekker, New York, Basle, 1990, vol. 50, ch. 3, p. 74. Davis, J. M., and Giddings, J . C., Anal. Chem., 1983, 55,418. Shi, W., and Davis, J. M.. Anal. Chem., 1993, 65, 482. Himberg, H., Sippola, E., and Riekkola, M. L., J. Micro- column Sep., 1989, 1,271. Bertsch, W., J. High Resolut. Chromatogr. Chromatogr. Commun., 1978, 1, 289,. Ragunathan, N., Krock, K. A., and Wilkins, C. L., Anal. Chem., 1993, 65, 1012. Krock, K. A., Ragunathan, N., and Wilkins, C. L., J. Chromatogr., 1993, 645, 153. Jennings, W. G., Settlage, J. A., Miller, R. J., and Raabe, W. G., J. Chromatogr., 1979, 186, 189. Klawun, C., Sasaki, T., Wilkins, C. L., Carter, D., Dent, G., Jackson, P., and Chalmers, J., Appl. Spectros., 1993, 47, 657. Nitz, S . , Kollmannsberger, H., and Drawert, F., J. Chroma- togr., 1989,471, 173. Coleman, W. M., 111, and Gordon, B. M., J. Chromatogr. Sci., 1991, 29, 371. Bicchi, C., D’Amato, A., Frattini, C., Nano, G. M., and Pisciotta, A., J. High Resolut. Chromatogr., 1989, 12, 705. Gordon, B. M., Rix, C. E., and Borderding, M. F., J. Chromatogr. Sci., 1985, 23, 1. Adams, S. T., J. High Resolut. Chromatogr. Chromatogr. Commun., 1988, 11, 85. Paper 3104078J Received July 13, 1993 Accepted September 13, 1993

ISSN:0003-2654    

DOI:10.1039/AN9941900483

出版商:RSC    

年代:1994

数据来源: RSC

摘要:

Analyst, April 1994, Vol. 119 491 Enhanced Waveguide Raman Spectroscopy With Thin Films* Plenary Lecture S. Ellahi and R. E. Hestert Department of Chemistry, University of York, York, UK YO1 5DD A sensitive Raman analytical technique for the study of thin films, surfaces and interfaces is demonstrated. Waveguide Raman spectroscopy (WRS) provides for a non-destructive evaluation of thin films in the micrometre and sub- micrometre regime. High intensity propagating waves have been used to sample molecules within waveguides, and interfacial species have been sampled by the evanescent portions of the optical field which tail into the substrate and superstrate regions of the waveguide structure. Variations of the simple waveguide experiment have been explored in surface and interface studies.Both resonance Raman spectroscopy and, for the first time, surface-enhanced resonance Raman spectroscopy (SERRS) have been used in combination with the waveguide technique, providing further increases in sensitivity. Experiments performed include waveguide resonance Raman spectroscopy of chromophores (beta-carotene on a polymer surface; tetraphenylporphine sulfonate at a polymer/glass interface; poly(viny1 chloride) (PVC) degradation products incorporated within a PVC thin film, and a novel combination of SERRS with WRS to detect tris(2,2- bypyridine)ruthenium(n) chloride hexahydrate incorporated within a polymer thin film. Keywords: Optical waveguide; surface study; resonance Raman spectroscopy; surface-enhanced Raman spectroscopy Aim of Investigation In order to arrive at an understanding of surface interactions and of the correlations between the structure and properties of thin films, highly sensitive non-destructive techniques are required.In addition to good sensitivity, such techniques should have low detection limits, molecular specificity and, ideally, the capability to probe the thin solid films at different depths in a non-destructive manner. Waveguide Raman spectroscopy (WRS), one of the latest in a series of Raman techniques developed for the study of substrate-supported thin films, meets all of these requirements.1.2 This technique, presently with detection capabilities down to monolayer levels, promises to be generally applicable to a wide variety of thin-film materials. Signal intensities can be enhanced by a combination of WRS with resonance Raman spectroscopy (RRS), i.e., waveguide resonance Raman spectroscopy (WRRS) where the exciting wavelength is coincident with, or close to, an electronic transition in the molecule.There is selective enhancement of Raman scattered intensity from vibrational modes of the chromophore. Surface-enhanced RRS (SERRS) may also be * Internationale (CSI), York, UK, June 29-July 4, 1993. + To whom correspondence should be addressed. Plenary lecture, presented at the XXVIII Colloquium Spectroscopicum combined with WRS in order to improve the sensitivity of the technique further. This work reports the detection of molecular materials at surfaces and interfaces by the combined use of WRS, RRS and SERRS, demonstrating the optical waveguide to be a sensitive and versatile analytical tool.Experimental WRRS of Beta-carotene on a Polystyrene Surface Polystyrene in the form of transparent, colourless beads, with average relative molecular mass ( M , ) = 280000 and refractive index, n488 = 1.60, was obtained from Aldrich. Thin film waveguides (=3 pm thickness) were fabricated3 by spin- coating a pyrex (refractive index, n488 = 1.47) glass slide with polystyrene from solution in chlorobenzene (AnalaR grade, obtained from BDH chemicals). The spinning apparatus consisted of a 12 V motor fitted with a turntable. A pyrex glass slide was attached to the turntable and the surface of the slide cleaned with acetone. The dry slide then was covered with -2 cm3 of polymer solution (=18% m/v) so that the surface was completely wetted, and the power supply to the spinner switched on for -3 min.The spin speed was maintained at -2500 rev min-l. After spinning the waveguides were placed in an oven at 80 "C for =2 h in order to remove any remaining solvent. Synthetic beta-carotene (purity >97%), obtained from Fluka, was dissolved in ethanol (spectrophotometric grade, obtained from Aldrich) prior to deposition on the surface of the polymer waveguide, using an evaporation method. A section of glass tubing, open at both ends, was attached to the polymer surface by the use of a Dow Corning 'Silastic' silicone rubber multifunctional sealant and left to set for ==l h. Beta-carotene solution (0.2 cm3 of a 3.17 x mol dm3) in ethanol then was measured into the deposition cell, and this assembly placed in an oven at a temperature of -80 "C for -30 min in order to evaporate the solvent.The waveguide was removed from the oven, allowed to cool and then the deposition cell carefully removed, taking care not to damage the polymer film. The structure and ultraviolethisible (UV/VIS) absorption spectrum of beta-carotene are shown in Fig. 1. WRRS of TPPS at a PolystyrenelGluss Interface Tetraphenylporphine sulfonate (TPPS) (obtained from Nen- tech Ltd.) is a water soluble porphyrin, the structure and UV/ VIS absorption (a mixture of neutral and protonated forms at pH 5) of which is shown in Fig. 2. An aqueous solution of TPPS (1 x mol dm-3) was prepared and deposited at the surface of a soda-glass (n488 = 1.52) microscope slide using an evaporation method similar to that used for carotene on polystyrene.The slide then was overcoated with a film of polystyrene (-15 pm thick) from chlorobenzene solution, using the spinning method described above. This sandwich492 Analyst, April 1994, Vol. 119 structure was replaced in the oven and left for -1 h to allow any remaining chlorobenzene to evaporate. The waveguide was removed from the oven and allowed to cool before it was used. WRRS of Degraded Poly(viny1 chloride) Poly(viny1 chloride) (PVC) in the form of shreds, and with n488 = 1.55, was obtained from ICI. PVC waveguides were prepared from solution (0.17% m/v) in tetrahydrofuran (THF; obtained from BDH) by a horizontal flow method. This involved covering a Pyrex glass microscope slide with =2 cm3 of solution and tilting the slide to allow the solution to flow slowly over the surface, wetting it completely. This was then left in a covered beaker for -2 h in order to allow the solvent to evaporate slowly.The slide then was transfeved to an oven (set at 80 "C) for -30 min to remove any remaining solvent. 200 300 400 500 Wavelengthhm Fig. 1 Structure and UVNIS absorption spectrum of beta-carotene in cyclohexane solution so,- 400 450 500 550 Wavelengthhm Fig. 2 Structure and UVNIS absorption spectrum of TPPS in aqueous solution Waveguide SERRS of Tris(2,2-bypyridine)ruthenium(11) Chloride Hexahydrate Polyvinyl alcohol (PVA; obtained from Aldrich), was used in powder form, 100% hydrolysed, M , = 86000 and na8 = 1.52. Tris(2,2-bipyridine)ruthenium(r1) chloride hexahydrate [Ru(bpy)32+] was obtained from Strem Chemicals Inc.A solution of PVA ( ~ 3 0 % m/v) was prepared by dissolving the powder in water. Silver sol was prepared by a standard procedure4 involving the reduction of aqueous silver nitrate (obtained from Fisons and of analytical-reagent grade) with sodium tetrahydroborate (analytical-reagent grade obtained from Aldrich). A sample of R~(bpy)~2+ in silver sol was prepared (1.1 x rnol dm-3 in silver) by the addition of an aqueous solution of R~(bpy)~2+ to a sample of silver sol. On addition of the R~(bpy)~2+ complex, the sol changed colour from yellow to blue-green. The structure and UVNIS absorption spectrum of the R~(bpy)~2+-silver sol sample is shown in Fig. 3. Some of the Ru(bpy)32+-silver sol (3 cm3) then was added to the colourless 30% PVA solution (3 cm3).The resulting PvA-R~(bpy)~2+- silver sol, which had a final Ru(bpy)32+ concentration of 5.5 x rnol dm-3, was stirred at room temperature for =48 h to produce a viscous, homogeneous solution. The sample was then only faintly coloured, though still blue-green. Thin (-3.5 pm) film waveguides were prepared by a spinning method, as described above for polystyrene. rnol dm-3 in R~(bpy)~2+ and 1.8 X rnol dm-3 and a concentration in silver of 9 x Waveguide Raman Spectroscopy WRS is based on an optical waveguide and achieves enhance- ment of Raman scattering by the combination of a high optical field intensity and a large sampling volume. A focused laser beam is coupled into a thin film of micrometre thickness at a controlled angle by means of a high index prism (see Fig. 4).Providing that certain refractive index conditions are met ,I i.e., n(prism) > n(film) > n(substrate), n(superstrate), the optical field is concentrated within the thin film and has a particular distribution according to the waveguide mode excited. In each experiment the laser beam was coupled into the waveguide and the incident angle set within the guiding range, calculated from the refractive indices of the system.' In recording the evanescent-field WRR spectra of beta-carotene (Fig. 5) and of TPPS (Fig. 6), the collection optics were first aligned with a strong signal from the polystyrene guiding layer and then re-aligned using a strong signal from the coloured deposit. The evanescent field was maximized by fine tuning 300 400 500 600 700 800 Wavelengthhm Fig. 3 UVNIS absorption spectrum of Ru(bpy)32+ in silver sol, and structure of Ru(bpy)32+.Concentration of Ru(bpy)32+ = 1.1 x mol dm-3. Concentration of silver = 1.8 x rnol dm-3. This sample was used to prepare thin (3.5 pm) film doped PVA waveguidesAnalyst, April 1994, Vol. 119 493 the incident angle whilst optimizing the signal from the beta- carotene or porphyrin. In the third experiment, the PVC film was degraded by in-coupling the 514.5 nm laser beam and leaving the sample guiding with -110 mW power at the sample. This was left for -1 h and then RR spectra (Fig. 7) were recorded using a reduced laser power of =40 mW at the sample. In the final experiment waveguide SERR spectra (of the PVA-Ru(bpy)32+-silver sol thin film waveguide) [see Fig.8(a)-(c)], were recorded at 476.5 and 514.5 nm. There was no strong Raman signal from the PVA polymer and therefore the collection optics had to be aligned directly on the Ru(bpy)32+ signal. All Raman spectra were recorded with a Jobin-Yvon Ramanor HG2 spectrometer system fitted with a photomulti- plier tube detector. Laser radiation was provided by an argon ion laser. Results and Discussion In the first experiment the amount of beta-carotene detected at the polystyrene surface and shown as Fig. 5, was calculated to be -120 ng. This was based on the concentration of the deposition solution, the surface area of the coated region and that of the interrogating waveguide streak and the collection conditions (optics magnification factor and spectrometer slit- width).The length of the interrogating waveguide streak was =1 mm in the coated sample, as compared with lengths of up A M Fig. 4 Diagram showing waveguide optics coupled to the waveguide. M = mirror, I = focusing lens, L = collection lens and P = coupling prism 1009 1 59 1193 1000 1100 1200 1520 1540 1560 1580 Wavenumbedcm-' Fig. 5 WRR spectrum of beta-carotene on a polystyrene surface (polystyrene spectrum subtracted), showing a detection of = 120 ng of beta-carotene. hex = 488 nm, laser power at sample = 80 mW, acquisition time = 4 min. All bands are due to beta-carotene to 20 mm obtained in the uncoated polymer. The laser excitation wavelength, 488 nm, was close to coincidence with the maximum of the main absorption band of beta-carotene (see Fig.1) and therefore provided resonance enhancement. The WRR spectrum of beta-carotene (Fig. 5) is comparable in signal-to-noise ratio with standard RR spectra, which typically have required larger samples.5.6 Fig. 6 shows the WRR spectrum ( a ) of TPPS and the standard RR spectrum (b) of TPPS in aqueous solution. The laser excitation wavelength, 457.9 nm, is at the edge of the absorption band. The amount of porphyrin detected was estimated to be -1 pg. The waveguide streak was -2 mm long, as compared with a typical length of 2 mm obtained in polystyrene waveguides. It is clear from Fig. 6 that the strongest porphyrin bands (at -1235 and 1540 cm-I) are of comparable intensity to the strong .=lo00 cm-l band due to the polystyrene ring breathing mode. This is despite the volume of polystyrene sampled being much greater than that of the porphyrin sampled, and that polystrene has a high Raman scattering cross-section.The strong porphyrin signals in the WRR spectrum must be due to a highly intense evanescent field, because 457.9 nm is at the edge of the absorption band, so that there can be little resonance enhancement at this excitation wavelength. Overcoating a a ) PS 1002 P 1538 1232 1000 1100 1200 1300 1400 1500 1600 Wavetengthkm-' Fig. 6 Raman spectra of TPPS (a) WRR spectrum of TPPS at a polystyrene/soda-glass interface showing polystyrene (PS) and porphyrin (P) bands. Unmarked bands have contributions from both polystyrene and porphyrin. hex = 457.9 nm, laser power at sample = 27 mW, acquisition time = 112 min. (b) RR spectrum of TPPS in aqueous solution.he, = 457.9 nm, laser power at sample = 27 mW, acquisition time = 12 min494 Analyst, April 1994, Vol. 11 9 sample with a guiding layer and probing with the evanescent field at the substrate seems to be a more fruitful method of carrying out surface WRS. The field at this surface is generally much higher than at the superstrate surface and can be increased by the use of low refractive index films (andor high index substrates). Fig. 7 shows the WRR spectra, at three excitation wavelengths, for a PVC thin film incorporating polyene degradation products. An analysis7 of the WRR spectra revealed the concentration of the polyene degradation products to be -20 ppm. As a result of resonance enhance- ment the bands due to the polyenes (at -1500 and 1160 cm-I) are comparable in intensity to those due to the polymer which constitutes 99.998% of the sample.Prolonged exposure of the sample to laser irradiation was found to cause some further increase in the relative intensities of the polyene bands. In 136 1111' \ I \ 1111' A 1493' 11 17' 1500' 1435 A 800 loo0 1200 1400 Wavenurnbedcm-' Fig. 7 WRR spectra of degraded PVC, showing polyene bands at ~ 1 5 0 0 and 1100 cm-l. (a) hex = 488 nm, (b) Lx = 476.5 nm, (c) hex = 459.7 nm. In each case, laser power at sample = 40 mW, acquisition time = 33 min addition, the spectra are excitation wavelength dependent [see Fig. 7(a)-(c)]. The UVNIS absorption of polyenes is dependent on the length of the polyene7 and therefore RR spectroscopy can be used to characterize the polyene sequences present in degraded PVC.7 The length of the waveguide streak in this experiment was not attenuated significantly as compared with an undegraded sample and remained at -10 mm.This is in keeping with the low level of polyenes present in the sample. In the final experiment the amount of Ru(bpy)32+ detected in the thin film waveguide SERR spectra, shown as Fig. 8, was calculated (from the solution concentration and volumes and the waveguide streak dimensions) to be =60 pg. The waveguide streak was -3 mm long, as compared with -6 mm observed with thin undoped PVA films. Two excitation wavelengths were used: 514.5 nm, which is under the long wavelength absorption band (see Fig. 3) due to the aggregated silver particles,3.4 and 476.5 nm, which is under the absorption band (see Fig.3) due to the R~(bpy)~2+ complex8 and avoids interference from fluores- cence emission due to the R~(bpy)~2+.8 Thus WRS and k I I I I I 1200 1 300 1400 1500 1600 Wavenurnber/crn-' Fig. 8 Waveguide SERR spectra of Ru(bpy)3*+ obtained from a thin (3.5 pm) PVA film doped with Ru(bpy)3*+ (adsorbed to colloidal silver surface) on a quartz substrate. (a) LX = 514.5 nm. Background subtracted. Spectral slit width = 7 cm-'. (b) hex = 514.5 nm. Spectral slit width = 7 cm-1. (c) he, = 476.5 nm. Spectral slit width = 8.3 cm-l. Scanning conditions: laser power at sample = 16 mW, acquisition time = 18 minAnalyst, April 1994, Vol. 119 495 SERRS have been successfully combined and the separate wavelength dependencies of the resonance and surface-en- hanced Raman spectroscopy (SERS) enhancement effects have been utilized in this Ru(bpy)32+-silver sol-PVA study.These results demonstrate that waveguide SERRS is a promising technique for the study of surface species and of interactions between a host matrix and embedded guest molecules. The waveguide SERRS technique described in this work is the first reported SERS study of an adsorbate trapped in a polymer matrix. This technique is potentially applicable to studies of a wide range of adsorbates, including environmen- tally-sensitive species, excited states and any species where a solid medium is preferable to the aqueous environment of standard SERS. In preparing the samples for these waveguide studies care had to be taken not to damage the polymer surfaces (for example during attachment and detachment of the deposition cell).Such damage prevented in-coupling a n d or guiding in these regions of the sample. However, inhomo- geneities in the dye layers, or in the film thickness where relatively thick (> -10 pm) films were used, did not prevent the sample from guiding. It can be shown1 that an overall enhancement factor of =lo4 results from the use of a waveguide as compared with the bulk sampling geometry, i.e., WRS requires far less of the material that is required in the bulk sampling geometry for the same signal-to-noise ratio. This enhancement factor means that even with inefficient coupling (typically in the range of 10-15%) large enhancements result in good quality spectra of thin films.RRS is able to provide enhancement factors of up to -106 under optimum resonance conditions.9 SERS is able to provide enhancement factors up to =lO7,10 although factors of the order of 104-106 are more common.11.12 When combined with resonance and/or surface-enhanced Raman spec- troscopies, the waveguide technique thus has the potential for great sensitivity, with enhancement factors of the order of 1012. The experiments described here are preliminary studies and it is expected that improvements in detection limits will be made in future studies. We acknowledge the involvement of S. Bell, E. Sanchez de la Blanca, J. N. Moore and K. P. J. Williams with this work, and British Petroleum for financial support. 1 2 3 4 5 6 7 8 9 10 11 12 References Rabolt, J . F., and Swalen, J . D., Advances in Spectroscopy, Volume 26, eds. Clark, R. J . H., and Hester, R. E., Wiley, Chichester, 1988, pp. 1-36. Swalen, J. D., Santo, R., Tacke, M., and Fischer, J . , IBM J. Res. Develop., 1977, 21, 168. Ellahi, S. B., D. Phil. Thesis, University of York, York, 1993. Creighton, J. A . , Blatchford, C. G., and Albrecht, M. G., J. Chem. SOC., Faraday Trans. II, 1979, 75, 790. Saito, S., Tasumi, M., and Eugster, C. H., J. Raman Spectrosc., 1983, 14, 299. Batchelder, D . N., and Bloor, D., Advances in Znfrared and Raman Spectroscopy, Volume I I , eds. Clark, R. J . H., and Hester, R. E., Wiley, Chichester, 1984, pp. 133-209. Kip, B. J . , van Aaken, S. M., Meier, R. J., Williams, K. P. J., and Gerrard , D . L., Macromolecules, 1992, 25, 4290. Bradley, P. G., Kress, N., Hornberger, B. A., Dallinger, R. F., and Woodruff, W. H., J. Am. Chem. SOC., 1981, 103,7414. Clark, R. J. H., Advances in Infrared and Raman Spectroscopy, Volume I , eds. Clark, R. J. H. and Hester, R. E., Wiley, Chichester, 1975, p. 143. Moskovits, M., Rev. Mod. Phys., 1985, 57, 783. Albrecht, M. G., and Creighton, J. A., J. Am. Chem. SOC., 1977,99, 5215. Hildebrandt, P., and Stockburger, M., J . Phys. Chern., 1984, 88,5935. Paper 3f04358D Received July 23, 1993 Accepted October 15, 1993

ISSN:0003-2654    

DOI:10.1039/AN9941900491

出版商:RSC    

年代:1994

数据来源: RSC