ISSN:0003-2654    

DOI:10.1039/AN99318FP011

出版商:RSC    

年代:1993

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN99318FX013

出版商:RSC    

年代:1993

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN99318BX015

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANAL,YS‘I’, APKlL 1993, VOL. I18 41N Obituary Professor Dr. Wilhelm Simon Wilhelm Simon was born in 1929 in Switzerland, graduated in Chemistry at the Swiss Federal Institute of Technology in 19.53 and received his Ph.D. degree in 1956 at the Department of Organic Chemistry of the Swiss Federal Institute of Technol- ogy in Zurich (ETH). In 1961 and 196.5, respectively, he became ‘Privatdozent’ and ‘Assistenz-Professor’ for instrumental methods of analysis at the same school. He was promoted to ‘ausserordentlicher Professor’ in 1967 and since 1970 he was full professor in chemistry at ETH. During his early career his research interests included acid-base equilibria using glass electrodes, automation of elemental analysis of organic compounds, instrumentation in vapour pressure osmometry, Curie-Point pyrolysis instrumen- tation and pyrolysis-mass spectrometry.Since 1966, his research interests, however, were largely focused on studies of the ion selectivity of organic compounds and biological systems, the design of chemical sensors and their application in biology and medicine, as well as high resolution separation techniques. He wroteko-authored two books and about 440 papers/articles on these topics. During his career, 107 doctoral students received Ph.D. degrees at ETH from his group. He was Editor, member of the Editorial Board, or Advisory Editor of eight scientific journals and series on monographs, and was a member of The Royal Society of Chemistry, the American Chemical Society, the American Microchemical Society, the New York Academy of Sciences, the Chemical Society in Zurich, the Swiss Chemical Society, the Naturfor- schende Gesellschaft in Zurich, the Swiss Society of Chemical Industries (member of the board), the Association of Swiss Chemists (member of the board 1967-1981), the Swiss Society for Analytical and Applied Chemistry and the Swiss Society for Instrumental Analysis and Microchemistry .He received the Swiss Chemical Society Award, the Benedetti-Pichler Award of the American Metrochemical Society, the Fritz- Pregl-Medal of the Austrian Society for Analytical Chemistry and was an honorary member of the Hungarian Academy of Sciences, the Institute Grand Ducal, Luxemburg, and the Japan Society for Analytical Chemistry, as well as honorary doctor (horonis causa) of the Technical University in Budapest.He received the Talanta Medal in 1991. Professor Simon will be long remembered for his many scientific achievements, but particularly for his studies of ion transport and selectivity in ion-selective electrodes. His group have synthesized over 1000 synthetic carriers, and many are now used in commercial sensors, particularly in clinical analysis. He was a superb orator, and anyone who listened to any of his lectures at international conferences could only have been enriched by his clear and precise communication of his science. He enjoyed his life to the fullest, and was knowledge- able about many subjects outside of his scientific discipline. He is survived by his wife Agnes. Professor M . R. Smyth Dublin City University Chirality Medal Nominations are invited for the Chirality Medal to be awarded in 1993 at the 4th International Symposium on Chiral Discrimination in Montreal, Quebec, Canada. The Chirality Medal was instituted by the Italian Chemical Society in connection with the International Symposium on Chiral Discrimination in Rome in 1991. This Medal is awardcd to recognizc distinguished achievement in any aspect of the field of Chiral Discrimination. Nominations, together with a short supporting statement, should be sent before April 30, 1993, to: Professor A.F. Fell, Secretary, Chirality Medal Iionours Committee, Pharmaceutical Chemistry, University of Dradjord, Bradford, UK BD7 1DP.

ISSN:0003-2654    

DOI:10.1039/AN993180041N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

42 N ANALYST, APRIL 1993, VOL. 118 Book Reviews Concise Encyclopedia of Biological and Biomedical Measurement Systems Edited by Peter A. Payne. Pp. xiii + 490. Pergamon Press. 1992. Price f 140.00; US$240.00. ISBN 0-08-0361 88-9. In order to keep up-to-date and disseminate the information to as wide an audience as possible, it was decided to follow up the eight-volume Systems and Control Encyclopedia with a series of Concise Encyclopedias. This supplementary series is presented under the title ‘Advances in systems, Control and Information Engineering’. This volume is devoted to Biolog- ical and Biomedical Measurement Systems. It contains 85 articles, which are written by 81 authors and are arranged alphabetically with an extensive cross-referencing system. In addition to describing the fundamental measurement processes of transduction, signal processing and display, the articles illustrate the influence of anatomy and physiology on both the choice of measurement technique and the type of information obtained.The authors maintain a remarkably high standard and consistency when the diversity of both the techniques used and the influences on interpretation are considered. A large number of entries are related to investigating the function and imaging of specific organs and tissues. Biome- chanics, the development of mathematical models and the design of artificial or replacement organs also feature pro- minently. Whilst this is an essential reference work for biomedical engineers, it provides chemical and biochemical analysts with a refreshingly different insight into the problems of measurement.Some articles (e.g., absorption spectro- scopy, blood gas analysis, computer aided data acquisition and analysis, electrical safety, electrodes and magnetic resonance spectroscopy) are obviously relevant to many readers of The Analyst. There are others, such as those related to olefactory, taste and visual systems, which this reviewer found broadened his perception of the biological processes of the natural world. Amongst those few articles which this reviewer felt com- petent to subject to detailed criticism, there was one disap- pointment. It also illustrates the problem of keeping up-to- date. The section on clinical analysis i n the article on absorption spectroscopy did not review advances after 1979.It therefore omitted references to both centrifugal analysers and their suitability for rapid kinetic measurements, and to multi-layer so called ‘dry chemistry’ systems which employ various light reflectance procedures for mcasurernent. Analysts should be aware of this Encyclopedia as it would seem to have more relevance to their work than is superficially apparent. It can be a source of inspiration and may provide a solution to a difficult measurement challenge. R . S . Ersser Physical Methods of Chemistry. Second Edition. Volume IV. Microscopy Edited by Bryant W. Rossiter and John F. Hamilton. Pp. xi + 540. Wiley. 1991. Price f 109.00. ISBN 0-471 -08026-8. I found the title of this book rather misleading. I thought it could be useful as a source book for the application of a variety of methods of microscopy to a range of problems in the physical characterization of chemical systems.It is not. Instead its main theme is a small sub-sct of microscopic techniques. Of the ten chapters in the book, no lcss than eight are devoted to electron microscopy with a considerable emphasis on transmission and diffraction techniques. This represents over 65% of the text and cannot be described as a balanced view of the role of microscopy in the physical sciences. Despite these concerns, the subject matter is well laid out and the text is very readable. Seven chapters have been contributed by authors from the Center for Solid State Science, Arizona State University, and this brings a welcome coherence to a multi-author volume.This group of researchers are very well known, and they write authoritatively on the principles of electron microscopy, applications in biological systems, the imaging of crystal defects, high resolution imaging of materials, diffraction and microanalysis tech- niques. Much of the information has been published pre- viously in a variety of places, but this volume brings a great deal together in a very useful way. A short chapter on scanning electron microscopy does not come up to the standard of those on transmission techniques. It gives some fundamental background on contrast mechan- isms and analytical techniques, but is weak on applications. Walter McCrone is the almost inevitable choice for a substantial chapter on light and other microscopies. Again much of the material has been published many times before, but it is convenient to have it alongside the electron techniques. The final chapter deals with particle size measurement.Thc only link with the rest of the book is that microscopy is sometimes applied to this area, but the link is weak, and the chapter seems to belong to another book altogether. A surprising feature of thc book is that it does not seem to be very up-to-date. Confocal microscopy, which is busy revolutionizing the application of light microscopy to charac- terizing all kinds of physical systems, gets only a couple of paragraphs. Scanning tunnelling microscopy, which is having a major impact on the visualization of the surfaces of materials of all kinds, gets even less. Even in the area of electron microscopy, the use of cryo-techniques to stabilize and handle dynamically changing systems, such as multiphase fluids, is very poorly dealt with.Although published in 1991, the book gives a picture of microscopy which belongs to the mid 1980s. In summary, this book gives an excellent grounding in the use of the transmission elcctron microscope for materials characterization, although i t is not fully up-to-date. The remaining third of the book could have been omitted without much loss, and is unlikely to add to the argument for buying i t . R. M . Miller Ions, Electrodes and Membranes. Second Edition By Jiri Koryta. Pp. xiv + 198. Wiley. 1991. Price f12.95. ISBN 0-471-93080-6. This book sets out to introduce the reader to somc fundamen- tal aspects of electrochemistry by relating natural phenomena to underlying principles.It i(; written in a remarkably interesting and informative manner that gives a readability more akin to a good novel than a textbook. The introductory comments indicate the book is aimcd towards people entering the field from other areas; it fulfills this need rather well. Koryta takes a systematic approach of describing rather idealized experiments, explaining the general laws that relate to them and then discussing the consequenccs. This methodol- ogy works well, the reader is led gently through a subject thatANALYST, APRIL 1993, VOL. 118 43 N might otherwise be confusing and the essential science is put into context. This second edition reflects some of the recent progress in the field of membranes, membrane transport and new materials and the introductory sections have been simplified.The book is divided into three chapters each subject being named in the book title, thus it covers many important aspects of electrochemistry but is by no means comprehensive. However, each section is supplemented by a useful list of relevent and up-to-date references which make it easy for the reader to obtain supplementary information. The chapter on ions includes sections on: the formation of ions; conduction, conductors and solvation; electrolytes and non-electrolytes, acidity, protons in solvents, equilibria and dissociation, intracellular pH, macro acids and particle motion. The second chapter on electrodes describes aspects of oxidation and reduction, electrode potentials, galvonic and electrolytic cells, electrode reactions, rates and elcctrocataly- sis, electrolysis, corrosion, interfacial structure, electrochem- ical analysis, ultramicroelectrodes, light and electrodes. The third chapter on membranes has a distinct biological slant, it includes short sections on synthetic polymer mem- branes, analysis by membrane systems, biosensors, electro- chemical extraction, cell walls and biological membranes, active and passive transport and nerve action.Some of these sections are very short, barely an introduc- tion, but they serve to wet the readers appetite. This comment is not a criticism, too much information would change the admirable style of the text. The book is relatively inexpensive in softback form and I think it represents good value for money.I will recommend all my students read a copy! Jonathan Sluter Unified Equilibrium Calculations By William Benton Guenther. Pp. xvi + 314. Wiley. 1992. ISBN 0-471-53854-X. The problem of acid-base equilibria is all pervasive in chemistry. As acid-base equilibria are often involved in mechanisms of both inorganic and organic reactions, their role must be understood in interpretation of kinetic and equilib- rium data both in inorganic and organic chemistry. In analytical chemistry acid-base equilibria play an essential role in qualitative analysis, in all modes of titration, control efficiency of extractions of compounds with acidic and basic properties, they affect the absorbance of numerous organic and inorganic compounds, result in variations in measured values in potentiometry as well as polarography and voltam- metry.Separation processes in liquid chromatography are influenced by changes in acidity and analytical reactions in strongly acidic and strongly alkaline media commonly involve acid-base equilibria. In many instances the role of these equilibria is dealt with in an ad hoc manner with varying degrees of detailed understanding and rigorousness. This reviewer agrees fully with the author that a unified approach to the role of acid-base equilibria promises better undcrstand- ing of special cases. The author expresses his debt to the pioneering work by J . E. Ricci (Hydrogen Ion Concentration, Princeton University Press, 1952) and his assessment that this book was often praised and little understood is probably correct.He is also right that the plethora of symbols was of considerable detriment to the use of this book. The present reviewer remembers even after some 30 years the struggle to follow the derivations in Ricci’s book, but the effort was worth it. Consequently, this reviewer appreciated the idea that a shorter, more focused treatment was presented by Guenther, which uses a more restricted number of symbols. Unfortu- nately this book, which in addition to general problems of acid-base equilibria covers also the problems of metal ion-ligand equilibria as well as the effects of acidity on solubility, does not fulfil all expectations. In numerous cases the author does not define clearly and unambiguously the terms being used and often uses shorthand descriptions, which might be understandable to the initiated, but are not rigorous enough.For example, the definitions of C,,, CAB, C,, C1, C,, and C, should be more clearly formulated and demonstrated by examples. In the statement (p. 5 ) . . . cx3 is the fraction as H3A . . . ‘as’ should probably be replaced by ‘of‘. The statement . . . (still using the K , direction) (p. 5 ) probably means that all equilibria are considered as acid dissociations. To restrict the number of common strong acids to those enumerated on p. 234 is misleading. At least fluorosulfuric and trifluoroacetic acids should be included, but also all acids used as Hammett-type indicators as well as carbocations. Volatility of 7 mol 1-1 HCl is not a simple expression of incomplete ionization, but reflects also the solvation equi- libria.Statement ‘Acids do not really “dissociate”’ is rather misleading (p. 234). Every acid-base reaction whether between an acidic compound and water (as a base) or reaction of an acidic compound with a basic one in benzene involves interaction of an acid with a base and if the base is a solvent we call such processes by convention ‘dissociation’. The statement ‘Unfortunately, there is no way to predict acid-base behaviour’ (p. 234) would not find positive accep- tance by D. D. Perrin, J . Shorter, and many of us. As pH is defined as -log aH+ and a glass electrode measures activity rather than concentrations of hydrogen ion, boldface used for activities by Ricci seems to be more logical than the use of boldface for concentrations (molarities) used here.Overall the differentiation between thermodynamic and practical equilibrium constants is not consistent; there are also surpris- ing omissions. The seminal text by A. Ringbom, Complexa- tion in Analytical Chemistry, Krieger, Huntington, New York, 1979, used at many European universities as the text for introduction of metal ion-ligand (author often uses abbre- viated form metal-ligand) is not quoted. Similarly, in the section dealing with pH-effects on solubilities, which is of particular interest to the pharmaceutical industry, the fun- damental paper on General Treatment of pH-solubility Profiles of Weak Acids and Bases and Effects of Different Acids on the Solubility of a Weak Base by W. H. Streng, S. K. Hsi, P.E . Helms, and H . G. H. Tan, J . Pharm. Sci., 1984,73, 1679 is not quoted. The use of spreadsheets for calculations in analytical chemistry has recently been reviewed by H. Freiser (CRC, Boca Raton) but this text might not have been available at the time when Guenther’s manuscript was finished. To summarize, for various reasons the present text cannot be recommended for tcaching purposes or student use, but will be appreciated by an experienced researcher in the area. Let us hope for a second edition, possibly with a more presentation minded co-author, which would keep the essen- tials, but eliminate the pitfalls. Petr Zuman Fiber Optic Chemical Sensors and Biosensors. Volume II Edited by Otto S. Wolfbeis. Pp. 358. CRC Press. 1991. Price f 127.00. ISBN 0-8493-5509-5.This second volume moves from the fundamentals of optica! sensing devices dealt with in Volume I to the specifics of targeted solute assay, device construction and applications in a series of 13 wide ranging multi-author chapters. The volume is timely, given that much has been written about chemical and biosensors, but with an emphasis invariably upon electro-44N ANALYST, APKII, 1993, VOL. 118 chemical devices. Indeed, the future may well lie with optical detection with perhaps (as the editor opines) special possibili- ties shown by luminescent-based probes. The various chapters present logical progressions of constructional and application complexity on the whole, though segregating the chapter on pH sensors into Volume I and the inclusion of a chaptcr on temperature sensors seems rather incongruous.Chapter 1 provides a brief overview of the many ion recognition strategies used in the detection of inorganic ions. While by no means an in-depth analysis, a full range of ingenious receptor molecule options reported to date are itemized. Oxygen sensors rightly have a complete chapter devoted to them, and receive the full treatment of principles, problems, fabrication and operational outcomes in a well illustrated chapter. The next chapter gives a general outline of other gas measuring techniques that exploit fibre optics and includes useful descriptions of methane, CO, nitrogen oxide and water vapour detection, along with a more standard coverage of NHJ, C 0 2 and H2 sensors. Adaptation to environmental analysis is considered next; the description of the ‘hardware’ and various field spectroscopic arrangements, which take up much of this chapter are, however, of more value to the instrumentation engineer than to the chemist with ambitions to apply recognition chemistry to improved chem- ical sensing.A short chapter on fibre optic use in titrimetry reminds us of a possible laboratory niche for fibre optic technology, particularly where visual end-point determination is difficult. To include a chapter on sensors for nuclear plants is, in principle, attractive but perhaps falls short of scientific relevance given that most of the systems amount to conven- tional spectrophotometry, with fibre optics simply providing the optical plumbing. The chapter on thermal sensing, though a little misplaced, is, nevertheless, a well rcsearched and liberally illustrated description of what is clearly an active research area with a diversity that equals anything in chemical sensors.As with electrochemical sensors, integration with an enzyme is the surest way of achieving an operational biosen- sor. Systems exploiting product (NH3, NADH, H+) or co-substrate ( 0 2 ) detection by optical fibre have been allocated a chapter, but more detailed descriptions of indivi- dual devices would not have gone amiss in view of the high interest and activity of this area. For many, the ncxt stagc of biosensors is the immunosensor, which though a potentially powerful system, presents the drawback of a non-revcrsiblc response, and lack of an end product for the sensing event.Adaptation of conventional immunoassay strategics to fibre optics are well reviewed, though with rather too much space devoted to standard immunochemistry and insufficient on the fast developing area of surface optical devices. Two succeed- ing chapters deal with medical applications, and give useful practical examples of structures designed for pH, pco2 and yo, monitoring that can be reliably (and safely) interfaced with blood or implanted into tissue. Bio- and chemiluminescence reactions are capable of extreme sensitivity and avoid the need for a light source; the operational principles of these promising probes are presented in a separate chapter along with indication of the biocatalysts with which thcy can be used. The final chapter includes a generally useful discussion of mol- ecular parameters that determine biorecognition, with special emphasis on cell membrane receptors and their incorporation into natural and artificial lipid bilayers; if the engineering and biophysics can be sorted out, therein surely lies the future.A balance is t o be struck between a perfectly presented and extensive monograph that is out-of-date by the time of publication, and one that is a communications failure by being rushed off to press. This issue achieves a satisfactory balance between the two extremes and, accordingly, is of value to anyone with a specialist or indeed non-specialist eye for optical sensors. Pankuj Vadgumu Target Sites for Herbicide Action Edited by Ralph C. Kirkwood. Topics in Applied Chem- istry. Pp.xiv + 339. Plenum. 1991. Price US$79.50. ISBN 0-306-43846-1. The professional analyst with an enquiring mind may desirc to know more about physiologically active molcculcs or the metabolites thereof, which he may bc detecting and mcasur- ing. If these arc herbicides and he wishes to know how they work he will be attracted by the title of this book. Ralph Kirkwood has long cxpcricnce of the subjcct. He has written one chapter himself and for thc rcst he assembled a team of 11 othcrs, mainly from the UK, but two locatcd in the USA. All are very compctcnt authorities on their topics. However, the book is largely one for the specialist and not for thc faint-hearted; it starts as it means to go on. The very first chapter is a skilled account of the interaction of herbicides with the photosynthetic process, which reyuircs a basic grasp of modern plant biochcmi\try.The ncxt three chapters consider amino acid synthesis, lipid \ynthcsis and carotcnoid biosynthcsis as targets, respectively, followed by a fifth chapter on a range o f othcr primary target sites. The second half of the book cover\ diverse but related topics. This starts with a chaptcr on chemicals that can modify the action of herbicides. Next comcs consideration of how herbicides reach their target sites. This is divided between three chapters, the first of which discusses the influence of processes in the soil. Where herbicides are applied direct t o foliagc other pathways and mechanisms of uptake arc involved and can be influenced by surfactants. Following a chapter o n that subject, comes one on the ongoing transport of herbicides within the plant. The book concludcs with a chapter on herbicide metabolism a s a basis tor selectivity.This volume is an cxcellcnt introduction to the detailed literature. Thc chapters are well illuslratcd by chemical structures, biochcmical pathways and experimental data. Each chapter has a comprehensive rcfcrcnce list, the shortest of which contains 77 and the longest 225 citations! Sadly, this book i\ let down at the end. A list of ‘Chemical names of compounds mcntioncd in the text’ is incomplete. Many chemicals referred to only by the manufacturer’s code number are not listed, evcn though the structure might even have bcen illustrated i n a figure. The index shows many inadequacies.Thcre are many examples of index entries for spccific herbicides or groups of herbicides where refcrcnce i s made to one part of thc book but n o t to an equally important consideration of its aclion elsewhere. Entrics for plants, crops or weeds, are cqually erratic. By and large, if the Latin name is i n the text it is indexed, but not if only thc English name has bccn uscd by the author o f a chapter. K . Holly Nuclear Magnetic Resonance. Volume 21 Senior Reporter G. A. Webb. Specialist Periodical Reports. Pp xxii + 594. The Royal Society of Chemistry. 1992. Price f 145.00. ISBN 0-851 86-442-2. This latest volume of this wcll-respected series retains the format and style of previous volumes and covers the literature given in CA Selects-NMR Chemical Aspects from June 1990 to May 1991.‘Thus the majority of references quoted will bc for 1990 with a number from 1991. Intercstingly, I found references from 1952 quoted in this volume, which does seem somewhat anomalous. Chapter 1 (35 pages) is a comprehensive list of books and reviews compilcd by the senior reporter; 570 in all, an amazing number. In chapter 2 (33 pages) C. J . Jameson reports onANALYST, APRIL 1993, VOL. 118 4SN Theoretical and Physical Aspects of Nuclear Shielding, covering ah initio and semi-empirical calculations and some other aspects of nuclear shielding. Chapter 3 is entitled ‘Applications of Nuclear Shielding’ (36 pages) by I . P. Gerothanassis and C. Efthimiou and covers most other aspects of nuclear shielding including shielding of particular nuclei from Groups IA through to 0.In Chapter 4 (16 pages) H. Fukui gives a resume of work on the theoretical advances in the calculation of spin-spin couplings, by both ab initio and semi-empirical methods, and Chapter 5 (49 pages) by K. Kamienska-Trela complements the above in reporting the applications of spin-spin couplings, most of which understan- dably, involve couplings with hydrogen. Chapter 6 (30 pages) by H. Weingartner is devoted to Nuclear Spin Relaxation in Liquids, including structural and dynamic aspects and selected applications, and in Chapter 7 (49 pages) C. J. Groombridge reports on the large amount of work on Solid-state NMR including organometallics and silicates. Multiple Pulse NMR is covered in Chapter 8 (20 pages) by L. Y. Lion and J.C. Yang which includes various experimental procedures and also applications to structural problems. Chapters 9 (33 pages) by H. G . Parkes and 10 (23 pages) by A. H. Fawcett cover Natural and Synthetic Macromolecules, respectively, with sections on peptides, nucleotides and saccharides (Chapter 9) and liquid crystals and solid-state studies (Chapter 10). Conformational Analysis is dealt with by C. Jones in Chapter 11 (32 pages), which includes small organic molecules and nucleic acids, proteins and carbohy- drates. Some overlap with Chapter 9 is inevitable, but is not excessive. In Chapter 12 (30 pages) P. G . Morris reviews the NMR Spectroscopy of Living Systems including experimental advances and applications to both cell and tissue studies. NMK Imaging is dealt with in Chapter 13 (40 pages) by S.C. R. Williams who reports on instrumentation, contrast agents and solid-state imaging and other developments, and liquid crystals is covered in Chapter 14 (30 pages) by C. L. Khetrapal and K. V. Ramanathan. Finally, in Chapter 15 (42 pages) Heterogeneous Systems is reported by T. K. Halstead and includes polymers, solids and sorption on solid surfaces. There is only an author index. In conclusion the Senior Author is to be commended for coordinating this comprehensive reporting of the advances in Nuclear Magnetic Resonance. Perhaps comprehensive is the keyword. The problem for the practising NMR scientist is the quick and efficient retrieval from the literature of whatever one is interested in at the time. One wonders, with the advent of floppy disks with databanks and retrieval programs included, that perhaps this format should be seriously considered for these volumes in future.R. J . Abraham Spectroscopy of Advanced Materials Edited by R. J. H. Clark and R. E. Hester, Advances in Spectroscopy, Volume 79, Pp. xix + 405. Wiley. 1991. Price fll5.00; ISBN 0-471-92981-6. This book is number 19 of the highly acclaimed series: Advances in Spectroscopy, originally entitled Advances in infrared and Raman Spectroscopy. Whereas the earlier volumes contained review articles covering a large variety of topics, the last four books have each been devoted to onc single topic. The present book treats the structure, constitu- tion and dynamics of processes occurring in various advanced materials, by spectroscopic techniques, which include infrared and Raman, pulsed neutrons and photoexcitation spectros- COPY.The volume contains six chapters, each ranging from 36 to 104 pages, written by experts in the fields. The chapters include organic conductors, non-linear optical matcrials, semi- and superconductors and conjugated systems. Thus, the materials covered in this book are not selected as a rcsult of mechanical strengths but rather as new materials of interest in electronics, e.g., in semiconductors, photoconductors and optical switches. In Chapter 1 t h e charge-transfer crystals and molecular conductors that can function as photoconductors and scintillators are investigated by infrared and ultraviolet spectroscopy, using reflection techniques. The new applica- tions within optoelectronics are illustrated by infrared conduc- tivity spectra.Non-linear optical spectroscopy of conjugated polymers (which are used in commercial dyes) is treated in Chapter 2. These compounds form a new class of one- dimensional semiconductors and the review examines the connection between non-linear optical properties and struc- tures of the excited states. Both two photon and third harmonic generation spectroscopies are applied to the studies of polydiacetylenes. In Chapter 3 the technique of pulsed neutron studies is presented and applied to magnetic and hydrogenous materials, and tunnelling spectroscopy is applied to interca- lated graphite; this technique is limited by the beam intensity of the nuclear reactor. The technique of pulsed neutron spectroscopy is still in its infancy, and the chapter describes the theory as well as the experimental set-up in some detail.The average spectroscopist or analytical chemist will find this chapter to be very specialized. Typical semiconductors such as GaAs, InP and ZnSe are treated in Chapter 4, dealing with photoluminescence spectroscopy of thin-film semiconductor materials. This effect arises from the radiative recombination of excited state species and charge carriers in solids, and the technique can be used in steady-state as well as in time- resolved spectroscopy. Chapter 5 contains a comprehensive review (104 pages) of vibrational spectroscopy of polyconjugated materials: poly- acetylene and polyenes. These polymers become extremely good electric conductors when they are chemically doped or when they arc photochemically excited. The applications in technology are obvious, although a full understanding of their conductivity is still lacking. The chapter contains a thorough treatment of the infrared and Raman spectroscopy of these polymers as well as normal coordinate analyses and quantum mechanical calculations and is for this reviewer the most successful chapter in the book. The photo-excitation spectro- scopy of polyaniline is treated in Chapter 6. Owing to their alternating ring-heteroatom structure the polyanilines differ from other polymers such as polyacetylene, polythiophene and polypyrrole and serve as interesting model compounds for new phenomena. There is no overlap between the chapters and there is a unified treatment throughout. The editors should be praised for using SI units and enforcing standard IUPAC nomencla- ture in the book, as they have done in all the previous volumes. The typography and quality of printing are excellent in this series as should be expected considering the high price of each volume. Peter Klaeboe

ISSN:0003-2654    

DOI:10.1039/AN993180042N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

46N ANALYST, APRIL 1993, VOL. 118 Conference Diary Date April 19-22 May 2-7 3-5 3-5 4-6 4-5 4-6 04 6-12 9-14 9-13 10-13 11-15 20-21 23-28 24-26 Conference Location ECIO '93: European Conference on Integrated Neuchatel, Optics Switzerland CLEO/QELS '93, The Thirteenth Conference on Lasers and Electro-Optics concurrently with the Quantum Electronics and Laser Science Conference EuroResidue 11: Residues of Veterinary Drugs Veldhoven, in Food The Netherlands Baltimore, MD, USA Fifth Symposium on the Analysis of Steroids Szombathely , Hungary Deauville Conference and Symposium on Analytical Sciences-SAS 93 France Deauville, ASTM Symposium On Quality And Statistics: Atlanta, GA, Total Quality Management USA 9th Optical Fibre Sensors Conference Florence, Italy Capillary Chromatography: the Spring Greenford, Symposium and Annual General Meeting of the Middlesex, Chromatographic Society UK Interpack'93 (Environmentally Justified Diisseldorf, Packaging) Germany HPLC '93, 17th International Symposium on Hamburg, Column Liquid Chromatography Germany EMAS '93-Modern Developments and Rimini, Applications in Microbeam Analysis Italy International Environment '93 and Analysis '93 UK London , IV Encontro de Usuarios de RMN Rio de Janeiro, Brazil 4th International Meeting on Scanning Laser Ophthalmoscopy , Tomography and Germany Microscopy Heidelberg, 41st ASMS Conference on Mass Spectroscopy Las Vegas, NV, USA 11th Dechema Annual Meeting on Biotechnology Germany Frankfurt, Contact 0.Parriaux, Conference Chair, Centre Suisse D'Electronique et de Microtechnique, Maladiere 71, Case Postale 41, CH-2007, Neuchatel, Switzerland Tel: +41 38 205 111.Fax: +41 38 205 630 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC Tel: +1 202 223 9034. Fax: +1 202 416 6100 Dr. N. Haagsma, Department of the Science of Food of Animal Origin, Faculty of Veterinary Medicine, University of Utrecht, P.O. Box 80.175, NL-3508 TD Utrecht, The Netherlands Tel: +31 30 535 365. Fax: +31 30 532 365 Professor S. Gorog, c/o Chemical Works of Gedeon Richter Ltd., P.O. Box 27, H-1475 Budapest, Hungary Tel: +36 1 157 4566. Fax: +36 1 157 1578 Sabine Lauras, Nicko & Cri Associes, 7 rue d'Argout, F-75002 Paris, France Tel: +33 1 42 33 47 66. Fax: +33 1 40 41 92 41 Scott Orthey, ASTM, 1916 Race Street, Philadelphia, PA 19103, 215/299-5507, USA Annamaria Scheggi, Instituto di Ricerce, Sulle Onde Elettromagnetiche, del Consiglio Nazionale delle Ricerche, Via Pancialichi, 64, Florence, Italy Tel: +39 55 43 78 512.Fax: +39 55 41 08 93 The Executive Secretary, The Chromatographic Society, Suite 4, Clarendon Chambers, 32 Clarendon Street, Nottingham, UK NG14BU Tel: +44 602 500596. Fax: +44 602 500614 Diisseldorfer Messegesellschaft mbH 'NOWEA', P.O. Box 32 02 03, Stockumer Kirchstrasse 61, D-W-4000 Diisseldorf 30, Germany Gesellschaft Deutscher Chemiker, Abteilung Tagungen, Varrentrappstrasse 40-42, Postfach 90 04 40, D-6000 Frankfurt am Main 90, Germany Tel: +49 69 79 17 360. Fax: +49 69 79 17 475 Abraham Boekestein, Mansholtlaan 12, Postbus 356, D-6700 Wageningen, Germany Eileen Davies, IE '93,12 Alban Park , Hatfield Road, St Albans, Hertfordshire, UK AL4 OJJ Tel: +44 727 855574.Fax: +44 727 841694 The Associacao de Usuarios de Ressonancia Magnetica Nuclear (Auremn) , A/C Sonia Maria Cabral de Menezes, Petrobras/Cempes/Diquim, Radial 2, Quadra 7,21910.240 Cidade Universitaria, Ilha Do Fundao, Rio de Janeiro, RJ, Brazil Reinhard Burk or H. E. Volcker, Augenklinik, Ruprecht-Karles-Universitat Heidelberg, Im Neunheimer Feld 400, 6900 Heidelberg, Germany Tel: +49 6221 56 66999. Fax: +49 6221 56 5422 American Society for Mass Spectrometry, P.O. Box 1508, East Lansing, MI 48826, USA Tel: +1 517 337 2548. Dechema, P.O. Box 970146, D-W-6000 Frankfurt am Main 97, Germany 20036-1023, USAANALYST, APRIL 1993, VOL. 118 47N Date 24-29 24-27 25-27 25-27 27-28 27-28 30-416 June 2-4 3 3-4 7-9 8-1 1 13-17 13-17 14-18 14-16 14-20 Conference Location XV Mendeleev Congress on General and Applied Chemistry Byelorussia Minsk, 15th International Symposium on Capillary Chromatography (ISCC) Italy Riva del Garda, Vth International Symposium on Quantitative Ghent , Luminescence Spectrometry in Biomedical Belgium Sciences Control and Instrumentation Exhibition ’93 2nd European Symposium on Analytical Supercritical Fluid Chromatography and Extraction (ESASF) European Conference on Environmental Pollution, Aquatic and Atmospheric Environment, Airwater Quality, Hazardous Wastes and Hydrology 41st ASMS Conference on Mass Spectrometry and Allied Topics Birmingham, UK Riva del Garda, Italy Helsinski, Finland San Francisco, CA, USA International Symposium on Analysis of Peptides Sweden Stockholm? NMR Symposium Turku, Finland European Conference on Analytical Brno, Chemistry, Chromatography and Czechoslovakia Spectroscopy and Thermal Analysis ESIS ’93: European Seminar on Infrared Lyon, Spectroscopy France The Seventh International LIMS Conference Egham, Surrey, UK 6th European Congress on Biotechnology Firenze , Italy 3rd Scandinavian Symposium on Chemometrics Arhus, Denmark EOQ ’93 World Quality Congress: Information, Communication, Knowledge and Finland Quality PREP-93, 10th International Symposium on Preparative Chromatography USA Helsinki? Arlington, VA, European Organization for Quality Control Helsinki , Suomi-Finland Contact Dr.V. N. Makatun, Organizing Committee of the Mendeleev Congress, Presidium of Byelorussian Academy of Sciences, 66, F.Scorina Avenue, Minsk, Byelorussia Professor Dr. P. Sandra, IOPMS, Kennedypark 20, B-8500 Kortrijk, Belgium Tel: +32 56 204960. Fax: +32 56 204859 Professor Dr. Willy R. G. Baeyens, Symposium Chairman, University of Ghent, Faculty of Pharmaceutical Sciences, Pharmaceutical Institute, Harelbekestraat 72, B-9000 Ghent, Belgium Tel: +32 91 21 89 51 ext. 246. Fax: +32 91 21 79 02 Stephen Ward, Enterprise Public Relations, 165 Kensington High Street, London, UK W8 6SH Professor Dr. P. Sandra, IOPMS, Kennedypark 20, B-8500 Kortrijk, Belgium Tel: +32 56 204960. Fax: +32 56 204859 Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5V7 Tel: +1 613 932 7702.Judith A. Sjoberg, ASMS, 815 Don Gaspar, Santa Fe, NM 87501, USA Tel: +1 505 989-4517. Fax: +1 505 989-1073 The Swedish Academy of Pharmaceutical Sciences Symposium on ‘Analysis of Peptides’, P.O. Box 1136, S-111 81 Stockholm, Sweden Tel: +46 8 24 50 85. Fax: +46 8 20 55 11 Professor J. Mattinen, Abo Akademi, Institution for Organisk Kemi, Akademig 1, SF-20500 Abo 50, Finland Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5v7 Tel: + I 613 932 7702. G. Lachenal, Laboratoire d’Etudes des Materiaux Plastiques et des Biomateriaux, Universitk Claude Bernard, Lyon 1, 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cddex, France Tel: +33 72 43 12 11. Fax: +33 78 89 25 83 The Conference Registrar, 18 Portway Drive, West Wycombe, Buckinghamshire, UK HP12 4AU Tel: +44 494 448048.Fax: +44 494 448154 Congress Secretariat, c/o Professor Laura Frontali, Department of Cell and Developmental Biology, University of Rome ‘La Sapienze’, P. le Aldo Moro 5, 00185 Rome, Italy Tel: +39 6 445 3950. Fax: +39 6 499 12351 SSC3 Secretariat, Department of Chemical Technology, Danish Technological Institute , Teknologiparken, DK-8000 Arhus C, Denmark Tel: +45 86 14 24 00. Fax: +45 86 14 74 45 Ann-Kristin Bergh, EOQ ’93 Congress Secretariat, P.O. Box 1, SF-02731 Espoo, Finland Tel: +358 (9)800 08254. Fax: +358 0 509 1807 Ms. Janet Cunningham, Barr Enterprises, P.O. Box 279, Walkersville, MD 21793, USA Tel: + 1 301 898 3772. Fax: + 1 301 898 5596 Mrs. Tarja Jalasto, Finnish Society for Quality Control, Laaksolahdentie 41, P.O.Box 1, SF-02730 Espoo, Suomi-Finland Tel: +358 800 08254. Fax: +358 0 509 180748N ANALYST, APRIL 199.7, VOL. 118 Date 16 16-18 17-18 27-117 28-29 29-417 29 29 Conference Substances and Processes Dangerous to the Environment Location Preston, Lancashire, UK Contact Dr. Paul Illing, Health and Safety Executive, R425 Magdalen House, Stanley Precinct, Bootle, UK L20 3QZ Tel: +44 51 951 3420. Fax: +44 51 922 7918 Dr. Ivan E. Leigh, CertainTeed Corp., 1400 Union Meeting Road, P.O. Box 1100, Blue Bell, PA Tel: +1 215 341-6622. Fax: +1 215 341-6291 Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H sv7 Tel: +1 613 932 7702. Gill Spear, Pergamon Seminars, c/o Elsevier Advanced Technology, Mayfield House, 256 Banbury Road, Oxford, UK OX2 7DH; Tel: +44 865 512242.Fax: +44 865 310981 or for North America, Kim Cavellero, Pergamon Seminars, 660 White Plains Rd., Tarrytown, NY 10591-5153, USA XXVIII CSI Secretariat, Department of Chemistry, Loughborough University of Technology, Leicestershire, UK L E l l 3TU Tel: +44 509 222575. Fax: +44 SO9 233163 Dr. B. I,. Sharp, Loughborough University of Technology, Department of Chemistry, Loughborough, Leicestershire, UK L E l l 3TU XXVIII CSI Secretariat, Dcpartment of Chemistry, Loughborough University of Technology, Leicestershire, UK L E l l 3TU Tel: +44 509 222575. Fax: +44 509 233163 XXVIII CSI Secretariat, Department of Chemistry, Loughborough University of Technology, Leicestershire, UK LEI 1 3TU Tel: +44 SO9 222575.Fax: +44 SO9 233163 19422-0761, USA 5th Symposium on Chemically Modified Surfaces Malvern, PA, USA International Conference on Analytical Chemistry and Applied Chromatography/ Spectroscopy Toronto, Canada Fullerenes '93, 1st International Interdisciplinary Colloquium on the Science and Technology of the Fullerenes Santa Barbara, CA, USA XXVIII CSI Pre-Symposium: Analytical Spectroscopy in the Earth Sciences Kingston, UK XXVIII Colloquium Spectroscopicum Internationale York, UK XXVIII CSI Pre-Symposium: Introductory Chemometrics York, UK XXVIII CSI Pre-Symposium: Vapour Generation Techniques York, UK July 4-9 4-8 4-7 4-9 4-6 4-6 4-7 11th International Meeting on NMR Spectroscopy Swansea, UK Dr. J. F. Gibson, Secretary (Scientific), The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 71 437 8656.Fax: +44 71 437 8883 Professor Olli Seppanen, SF-021 SO Espoo, Finland 6th International Conference on Indoor Air Quality and Climate, Indoor Air'93 XXVIII CSI Post-Symposium: Graphite Atomizer Techniques in Analytical Spectroscopy Helsinki, Suom i-Fin 1 and Durham, UK XXVIII CSI Post-Symposium, Department of Chemistry. (CSI Secretariat), Loughborough University of Technology, Loughborough, Leicestershire, UK L E l l 3TU Tel: +44 509 22575. Fax: +44 SO9 233163 Dr. Stefan Nordlund, FEBS '93, Department of Biochemistry, Arrhenius Laboratories, Stockholm University, S-10691 Stockholm, Sweden XXVIII CSI Secretariat, Department of Chemistry, Loughborough University of Technology. Leicestershire, UK LEI 1 3TU Tel: +44 SO9 222575.Fax: +44 509 233163 Kym E. Jarvis or John G. Williams, NERC ICP-MS Facility, Department of Geology, Royal Holloway College, Egham, Surrey, UK TW20 OEX Tel: +44 784 44383514. Fax: +44 784 443836 XXVIII CSI Secretariat, , Department of Chemistry, Loughborough University of Technology, Leicestershire, UK L E l l 3TU Tel: +44 509 222575. Fax: +44 509 233163 22nd Meeting of the Federation of European Biochemical Societies Stockholm, Sweden XXVIII CSI Post-Symposium: Spectroscopic Data-Handling York, UK XXVIII CSI Post-Symposium: 5th Surrey Conference on Plasma Source Mass Spectrometry Durham, UK XXVIII CSI Post-Symposium: Analytical Applications of Glow Discharges in Optical and Mass Spectrometry York, UKANALYST, APRIL 1993, VOL.118 49N Date 7 11-15 11-14 11-15 12-14 19-21 19-23 25-29 Conference Location XXVIII CSI Post-Symposium: Trace Elements Durham, in Clinical Chemistry UK 25th Conference of the European Group for Atomic Spectroscopy France Caen, International Symposium on Polymer Analysis Crete, Greece and Characterization Chemometrics 111, 3rd Czechoslovak Brno, Chemometric Conference Czechoslovakia R & D Topics Meeting 1993 Bradford, W. Yorkshire, UK 6th Symposium on Handling of Environmental Guildford, August and Biological Samples in Chromatography 12th International Symposium on Nuclear Quadrupole Interactions 107th AOAC Annual International Meeting and Exposition 9-1 1 9-13 9-13 22-2s 22-27 22-27 23-27 23-27 3rd Soil and Sediment Residue Analysis Workshop Asianalysis 11: Second Asian Conference on Analytical Chemistry ILC '93: International Conference on Luminescence and Optical Spectroscopy on Condensed Matter Surrey, UK Zurich, Switzerland Washington, DC, USA Winnipeg, Manitoba, Canada Changchun, China Storrs, CT, USA EUROTOX'93 (32nd Congress of Toxicology) Uppsala , Sweden 206th ACS National Meeting (with Sessions of Chicago, IL, the Divisions of Analytical Chemistry, USA Environmental Chemistry, Chemical Health and Safety, etc.) Third International Symposium on Separation Antwerp, Technology Belgium 9th Meeting of EURO CVD Tampere, Finland 9th International Conference on Fourier Calgary, Transform Spectroscopy Alberta, Canada Contact XXVIII CSI Secretariat, Department of Chemistry, Loughborough University of Technology, Leicestershire, UK LE11 3TU Tel: +44 509 222575.Fax: +44 509 233163 25th EGAS Secretariat, IS-MRA, Labo. Spectro. Atom., Boulevard Markchal Juin, F-14050 Caen, France Judith A. Sjoberg, Professional Association Management, 815 Don Gaspar, Sante Fe, NM 87501, USA Tel: +1 505 989 4735. Fax: +1 505 989 1073 Dr. Josef Havel, Department of Analytical Chemistry, Masaryk University, Kotlarska 2, CS- 61137 Brno, Czechoslovakia Tel: +42 5 712984. Fax: +42 5 740108 Miss P. Hutchinson, Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly , London, UK W1V OBN Tel: +44 71 437 8656. Fax: +44 71 734 1227 M. Frei-Hausler, IAEAC Secretariat. Postfach 46, CH-4123 Allschwil 2, Switzerland Tel: +41 61 632789. Fax: +41 61 4820805 Professor D.Brinkmann, Physik-Insti tut, University of Zurich, Schonberggasse 9, CH-8001 Zurich, Switzerland Margaret Ridgell, AOAC, 2200 Wilson Boulevard, Suite 400, Arlington, VA 22201-3301, USA Dr. G. R. Barrie Webster, Pesticide Research Laboratory, Department of Soil Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2. Tel: + 1 204 474 6039. Fax: + 1 204 275 6019; or Professor Dr. Joseph Tarradellas, IGE, Federal Technical Institute EPF-L, CH-1015 Lausanne Ecublens, Switzerland Professor Erkang Wang, Asianalysis 11, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, P.O. Box 1022, Changchun, Jilin 130022, China Tel: +86 431 682 801 (ext. 562). Fax: +86 431 685 653 Professor Douglas Hamilton, Physics Department, 2152 Hillside Road, University of Connecticut, Storrs, CT 06269-3046, USA Dr.R. A. Ettlin, EUROTOX Secretary General, Sandoz Pharma Ltd., Toxicology, Building 881, P.O. Box, CH-4002 Basle, Switzerland Mr. B. R. Hodson, American Chemical Society, 1155-16th Street N.W., Washington, DC 20036, USA Tel: + 1 202 872 4396. Mrs. M. Stalmans, University of Antwerp (UIA), Department of Chemistry, Universiteitsplein 1, B-2610 Antwerp-Wilrijk, Belgium Tel: +32 3 820 23 75. Fax: +32 3 820 23 74 Ms. Raili Siekkinen, Tampere University of Technology, P.O. Box 527, SF-33101, Tampere, Finland Lois Kokoski, Conference Office, The University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4 Tel: + 1 403 220 5051. Fax: + 1 403 284 5696SON ANALYST, APRIL 1993, VOL.118 Date 23-27 23-27 26-119 29-319 3 0 4 9 30-119 30-219 Conference Location 6th Hungaro-Italian Symposium on Spectrochemistry, Advances in Environmental Hungary Sciences 9th Danube Symposium on Chromatography Lillafur ed , Budapest , Hungary 5th International Conference on Electron Spectroscopy Ukraine 9th International Symposium: Advances and Application of Chromatography in Industry Kiev , Bratislava, Czechoslovakia 13th European Conference on Surface Science Warwick, UK 15th International Symposium on Safety in Interaction with Quality, Productivity and Economy Second European Symposium on Near Infrared Spectroscopy September 2-3 5-10 5-10 5-1 1 5-10 5-11 6-10 6-10 6-10 6-10 2nd UK International Meeting on Biological and Biomedical Applications of Scanning Probe Microscopy Ninth International Biodeterioration and Biodegradation Symposium Lugano , Switzerland Kolding , Denmark Nottingham, UK Leeds, UK 5th European Conference on the Spectroscopy Lontraki , of Biological Molecules Greece Euroanalysis VIII: European Conference on Analytical Chemistry UK Edinburgh , Second International Conference on the Biogeochemistry of Trace Elements Taipei, Taiwan, Republic of China Pharmacy World Congress '93 Tokyo, Japan 18th International Conference on Infrared and Colchester, Millimetre Waves UK Defect Recognition and Image Processing in Santander, Semiconductors and Devices Spain 1 lth Specialised Colloque Ampere on Magnetic Menton, Resonance in Homogeneous and France Heterogeneous Catalysis Second International Conference on Magnetic Heidelberg, Resonance Microscopy Germany Contact Dr.Gy. Zaray, Institute of Inorganic and Organic Chemistry, Lotvos University, P.O. Box 32, H-1518 Budapest , Hungary Professor L. Szepesy, Hungarian Chemical Society, Budapest , Hungary Tel: +36 1 186 9000. Fax: +36 1 181 2755 J. J. Pireaux, LISE, rue de Bruxelles, 61, B-5000 Namur, Belgium Assoc. Prof. Jozef Polonsky, Department of Analytical Chemistry, Slovak Technical University, Radlinskeho 9, 812 37 Bratislava, Czechoslovakia Tel: +42 7 560 43. Fax: +42 7 49 31 98 Dr. C. F. McConville, ECOSS-13, Department of Physics, University of Warwick, Coventry, UK CV4 7AL Tel: +44 203 523353. Fax: +44 203 692016 Secretariate ISSA, Section Chemistry, c/o BG Chemie, P.O. Box 10 14 80, D-W-6900 Heidelberg 1, Germany Lone Vejgaard, Biotechnological Institute, Holbergsvej 10, P.O.Box 818, DK-6000 Kolding. Denmark Tel: +45 75520433. Fax: +45 75529989 The SPM Laboratory, Department of Pharmaceutical Sciences , University of Nottingham , Nottingham, UK NG7 2RD Tel: +44 602 515101. Fax: +44 602 515102 The Conference Secretary (RE), Department of Chemical Engineering, The University of Leeds, Leeds, UK LS2 9JT Professor Th. Theophanides, National Technical University of Athens, Department of Chemical Engineering, Zogratou 15780, Athens, Greece Miss P. E. Hutchinson, Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 71 437 8656. Fax: +44 71 734 1227 Dr. Shang-Shyng Yang, Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan 106, Republic of China; or Dr. Domy C. Adriano, University of Georgia, Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA Professor D. J. A. Crommelin, FIP Congress Department, The Hague, The Netherlands Tel: +31 70 363 1925. Fax: +31 70 363 3914 Professor T. J. Parker, Department of Physics, University of Essex, Wivenhoe Park, Colchester, UK C04 3SQ Dr. Juan Jimhez, Drip 5, Universidad de Valladolid, 47011 Valladolid, Spain Professor J. Fraissard, Laboratoire de Chimie des Surfaces, Universite P. et M. Curie, 4, Place Jussieu (Boite 196), 75252 Paris Cedex 05, France Dr. Bernhard Bliimich, c/o Max Planck-Institute fur Polymerforschung, Postfach 3 148, D-6500 Mainz, Germany Entries in the above listing are at the discretion of the Editor and are free of charge. If you wish to publicize a forthcoming meeting please send full details to: The Analyst Editorial Office, Thomas Graham House, Science Park, Milton Road, Cambridge, UK CB4 4WF. Tel: +44 (0)223 420066. Fax: +44 (0)223 420247.

ISSN:0003-2654    

DOI:10.1039/AN993180046N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, APRIL 1993, VOI,. 118 51N Future Issues will Include- ton-selective Electrodes in the Analysis of Drug Substances: Potentiometric Microtitration of L-Ascorbic Acid With Copper(i1) Sulfate and its Application to the Analysis of Pharmaceutical Preparations-Antonio Campiglio Sensor Properties of Filled Polymer Composites-D. Yu. Godovski, E. A. Koltypin, A. V. Volkov and M. A. Moskvina Coupled Gas Chromatography-Atomic Absorption Spec- trometry Using Semi-enclosed Tubular Atomizers: Theo- retical Analysis of Detector Performance Characteristics- Douglas C. Baxter and Wolfgang Frech Decomposition of 2,6-Dichlorophenolindophenol in Strongly Acidic Solutions: a Potential Kinetic Method for the Determi- nation of pH-Miltiades I. Karayannis, Constantina N. Konidari and Christos G.Nanos Simultaneous Kinetic Fluorimetric Determination of Amoxy- cillin and Clavulanic Acid by the Stopped-flow Mixing Technique-Pilar Izquierdo, Agustina Gomez-Hens and Dolores Perez-Bendito Catalytic Method for the Determination of Trace Amounts of Mercury in Environmental Samples-A. Ramesh Extended Kalman Filter for Multiwavelength, Multi- component Kinetic Determinations-Stanley R. Crouch and Brett M. Quencer Determination of Dissolved Copper, Nickel and Cadmium in Natural Waters by High-performance Liquid Chromato- graph y-Sean Comber Determination of Trace Amounts of Heavy Metals in Alu- mina by Electrothermal Atomic Absorption Spectrometry After Diethyldithiocarbamate Extraction and Matrix Pre- cipitation-Masataka Hiraide, Takaaki Uchida and Hiroshi Kawaguchi Nitrate Ion-selective Coated-wire Electrode Based On Tet- raoctadecylammonium Nitrate in Solid Solvents and the Effect of Additives on Its Selectivity-Hirokazu Hara, Hiromi Ohkubo and Kaori Sawai 6,7-Dimethoxy-l-me thyl-2( lH)-quinoxalinone-3-propionyl- carboxylic Acid Hydrazide as a Fluorescence Derivatization Reagent for Aldehydes in High-performance Liquid Chromatography-Masatoshi Yamaguchi, Tetsuharu Iwata, Tsuyoshi Hirose and Masaru Nakamura Substitution of Peroxidase in Trinder’s Reagent With Iron(i1) for the Determination of Hydrogen Peroxide in Enzymic Reactions by Applying Flow Injection-Miltiades I. Karayannis, Efstratios R.Kiranas and Stella M. Tzouwara- Karayanni Determination of Lead in Urine by Electrothermal Atomic Absorption Spectrometry With Probe Atomization-David Littlejohn and Tianyu Chen Ultraviolet Spectrophotometric, Solvent Extraction, High- performance Liquid Chromatographic and Polarographic Study of an H+/K+ Adenosine Triphosphatase lnhibitor and its Acid-catalysed Degradation Products-W.F. Smyth, E. O’Kane, V. N. Ramachandran and S. McClean Intercomparison of Methods for the Determination of Vita- mins in Foods. Part l . Fat-soluble Vitamins-Peter C. H. Hollman, Peter J. Wagstaffe, Uta Faure, David A. T. Southgate, Paul M. Finglas and Jean H. Slangen Intercomparison of Methods for the Determination of Vita- mins in Foods. Part 2. Water-soluble Vitamins-Peter C. H. Hollman, Jean H. Slangen, Peter J. Wagstaffe, Uta Faure, David A. T. Southgate and Paul M. Finglas Surface Modification of the Biomedical Polymer Poly- (ethylene terephtha1ate)-Lan.N. Bui, Michael Thompson, Neil B. McKeown, Alex D. Romaschin and Peter G. Kalman Determination of Trace Amounts of Phosphate in Water After Preconcentration Using a Thermally Reversible Poly- mer-Kiyoko Takamura, Chiyo Matsubara, Sigeru Izumi, Hiroshi Yoshioka and Yuichi Mori 2nd National Symposium on Planar Chromatography: Modern Thin-Layer Chromatography Co-Chairmen: P r o f e s s o r Harold M. McNair and P r o f e s s o r Colin F. P o o l e September 19-22, 1993 Research Triangle Park, North Carolina,USA F u r t h e r information may be obtained from: Janet E . Cunningham, Barr Enterprises, P.O. Box 2 7 9 , Walkersville, MD 21793 USA Phone: ( 3 0 1 ) 898-3772 - Fax: ( 3 0 1 ) 898-5596EUROANALYSIS VIII The Eighth European Conference on Analytical Chemistry will be held at the University of Edinburgh September 5-11,1993 Organized by the Analytical Division of The Royal Society of Chemistry on behalf of WPAC/FE@S Scientific Prwamme Euroanalysis VIII will cover developments in instrumentation and methodology in all areas of analytical chemistry, with em- phasis on industrial, biomedical and environmental analysis.The programme will be designed to appeal to both practising analytical chemists in industry and those in academia who are teaching and carrying out research. The programme will consist of invited keynote lectures and contributed oral and poster papers. In order to ensure high quality, all contributed papers will be refereed. Social Promamme A comprehensive programme is being planned for participants and accompanying persons.It will include half- and full-day excursions, and various evening events including a whisky tasting and a Buffet Reception at the Royal Museum of Scotland. Publication All of the invited lectures will be published in a collected volume as the proceedings of the conference. Authors of con- tributed papers will be encouraged to submit manuscripts for publication in either The Analyst or the Journal of Analytical Atomic Spectrometry (JAAS). Topics Some of the topics covered are: Industrial Analysis Validation of Analytical Measurements, Process Control Analysis, Materials Analysis (including Surface Analysis), Energy Related Analysis Pharmaceutical Methods and Drug Metabolism, Forensic Science, Bioselective Methods, Trace Elements in Medicine Separation Science, Molecular Spectroscopy, Atomic Spectrometry, Electroanalytical Techniques, Expert Systems and Chemometrics,Coupled Techniques, Sensors, Laser- based Techniques, Flow Analysis Pharmaceutical and Biomedical Analysis Environmental Analysis Atmosphere, Soils/Sediments, Food/Drink,Water Instrumental Techniques Conference Secretariat: Honorary Chairman, E.J. Newman Conference Presidium: D.T. Bums, Belfast (Chairman); J.F.K. Huber, Vienna; L. Niinisto, Espoo; P.G. Zambonin, Bari Secretary and Conference Organizer: Miss P.E. Hutchinson, Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London W1V OBN, UK Tel. 071 437 8656; Fax 071 734 1227; Telex 268001 All correspondence and requests for further information should be addressed to the Conference Organizer.

ISSN:0003-2654    

DOI:10.1039/AN993180051N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, APRIL 1993, VOL. 118 Special Issue on 'Sensors & Signals' Guest Editors 315 Professor Malcolm R. Smyth PhD DSc CChem FRSC FICI University of London in 1976. He then studied as a Postdoc- toral Research Fellow at Colorado State University between 1976 and 1978, and was subsequently employed as a Visiting Research Scientist at the Nuclear Research Centre in Jiilich between 1979 and 1981. In 1981 he was appointed Lecturer in Analytical Chemistry at the (then) National Institute for Higher Education (NIHE) in Dublin (now Dublin City University). He became a Senior Lecturer in 1985 and took over as Head of the School of Chemical Sciences at Dublin City University in 1990. In 1990 he was awarded the degree of Doctor of Science (DSc) from The Queen's University of Belfast.In 1992 he was appointed Professor of Chemistry at Dublin City University. His research interests and experience are centred mainly in the fields of electroanalysis and chromatography. In particular, he is interested in the develop- ment of methods for the determination of substances of environmental or biological importance, with emphasis in the areas of microelectrodes, high-performance liquid chromato- graphy (HPLC) with electrochemical detection, inorganic applications of HPLC, electrochemical sensors and biosen- sors. He is the author/co-author of over 100 publications, and has edited three books. He is currently a member of the Editorial Board of The Analyst and serves on the Editorial Advisory Board of Analytical Letters, Talanta, Electroanaly- sis, Journal of Pharmaceutical and Biomedical Analysis, Analytical Chimica Acta and Encyclopaedia of Analytical Science.He is a Fellow of both The Royal Society of Chemistry and the institute of Chemistry of Ireland. Professor Malcolm R. Smyth obtained his Bachelors degree in Biochemistry from The Queen's University of Belfast in 1972 and his Ph.D. in Analytical Chemistry at Chelsea College, Dr. Dermot Diamond BSc MSc PhD CChem MRSC MICI Dr. Dermqt Diamond obtained his BSc in 1976 from The Queen's University of Belfast where he also obtained his MSc and PhD under the supervision of Professor Gyula Svehla on the development of novel ion-selective electrodes. He then moved to Dublin City University in 1987 and is now Senior Lecturer in the School of Chemical Sciences. He is a member of The Royal Society of Chemistry and a member of the Institute of Chemistry of Ireland. In addition, he has also served on several organizing committees for The Royal Society of Chemistry Annual Chemical Congress. His research interests include chemical sensors, sensor arrays and signal processing, computer-based data acquisition and control, virtual instruments and supramolecular chem- istry. He has over 30 publications in these areas to his credit.

ISSN:0003-2654    

DOI:10.1039/AN9931800315

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

316 ANALYST, APRIL 1993, VOL. 118 Guest Editorial Sensors and Signals The area of sensors is one of the most active in science today. It is a truly multidisciplinarian subject, which encompasses the traditional classifications of chemistry and biology, physics, electronics and mathematics. The main aim of the Analytical Division Symposium at The Royal Society of Chemistry Autumn Meeting held at Trinity College, Dublin, on Septem- ber 16-18, 1992, was therefore to reflect how these disciplines have come together to produce sensing devices and protocols which have a practical application in the areas of chemical and biological analysis. The symposium was given the title ‘Sensors and Signals’ owing to the growing importance of maximizing the information that can be obtained from sensors and, in particular, sensor arrays.This followed on from a small Irish national meeting held at Dublin City University in September 1990, the proceedings of which were subsequently published in Analytical Proceedings (1991, 28, 102). The Campunile, u local landmark and centrepiece of the main square at Trinity College, Dublin The first plenary lecture on recognition processes in chemical and biological sensors was to have been given by Professor Wilhelm Simon of ETH, Zurich, but owing to his recent illness he could not attend. It was, therefore, very sad to learn of his death on November 17,1992, and I am sure that everyone who attended the symposium will wish to record their appreciation of the great contribution Professor Simon made to the development of chemical and biological sensors, particularly in the area of ion-selective electrodes.The theme of recognition was therefore introduced by Professor Gordon Wallace, who dealt primarily with recognition of analytes at conducting polymer surfaces. The meeting then continued with a set of lectures relating to the various transduction processes used to transmit the signal to the measurement device. The third session was concerned with sensor arrays/ signal processing, where the use of various mathematical routines, such as neural networks and multivariate calibra- tion, were described to show how better information could be obtained from sensor signals, particularly from the often complex patterns obtained from sensor arrays. The following three sessions were then concerned with particular areas of sensor developments related to gas sensors, polymer-based sensors and biosensors.These sessions began with the Plenary Lecture of Professor JiEi Janata on the present state of fabrication of chemically sensitive field effect transistors. Five of the delegates at the Sensors and Signals Symposium, putting their own sensors to the test whilst in ‘Mulligans’, one of the more famous pubs in Dublin. L to R: Projessor Gordon Wullace, Dr. Vincent Cunnune, ProfesJor Malcolm Smyth, Dr. Richard Miller and Dr. Simon Higgins The quality of the work reported in both the oral and poster sessions was of a very high standard and it is hoped that this permanent record of the proceedings of the symposium will be welcomed by all those who witnessed the events and under- stood more about ‘the dancer and the dance’. As convenors of the symposium and Guest Editors of this special issue of The Analyst, we would like to thank all those who supported us at the meeting, and in particular Dr. Jeremy Glennon of University College Cork, who was involved in the early stages of the programme development. Malcolm R. Smyth Dermot D. Diamond Dublin City University

ISSN:0003-2654    

DOI:10.1039/AN9931800316

出版商:RSC    

年代:1993

数据来源: RSC

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ANALYST. APRIL 1993, VOL. 118 3 17 Tutorial Review Optical Chemical Sensors: Transduction and Signal Processing* Ramaier Narayanaswamy Department ot Instrumentation and Analytical Science, UMIST, P.O. Box 88, Manchester, UK M60 7QD The development of optical chemical sensors is a rapidly growing technology, and it combines the advantages of optical fibres with the selectivity and specificity of chemical transduction systems. The chemical transducer is the heart of such sensors and considerable effort is being made in their development. The analyte concentrations are determined through the measurement of chemically encoded optical signals. The optical signal processing is carried out using standard components and instrumentation t o produce quality and meaningful data. This paper reviews the principles of chemical transduction and the signal processing systems that are used in conjunction with optical chemical sensors.Keywords: Optical sensor; chemical transduction; optical instrumentation Optical methods have been used for several years in various fields of analyses. Some of the oldest and best known applications include the use of pH indicator strips for sensing pH and oxygen measurements by quenching the phosphor- escence of the dye trypaflavin adsorbed on silica gel.' However, a major achievement occurred when conventional optical sensing techniques were coupled with optical fibres. Although optical fibres were originally manufactured mainly for use in the communication industry they have been adapted to optical sensing devices. Optical fibres themselves allow transmission of light over long distances, and for chemical sensing typically 1-100 m distances are currently used.The advent of high quality, low optical fibres meant that this distance could be much greater. Additionally, the develop- ment of high performance and high quality optical com- ponents, including light sources (lasers, light emitting diodes), photodetectors, amplifiers, etc'., that can be used in conjunc- tion with optical chemical sensors has promoted rapid progress and great interest in this sensing technology. Optical fibre chemical sensors rely on an interdisciplinary approach to their development with expertise from the fields of analytical chemistry, physics (optics) and optoelectronics. Progress in this field of chemical analysis is mainly dependent on the ease and manner in which the chemical transduction system can be developed and interfaced with fibre optics.Furthermore, use of chemome trics and microprocessors, which allow storage and rapid analysis of data, has signifi- cantly contributed to the state-of-the-art of optical chemical sensors. Advantages and Disadvantages Chemical analysis is currently carried out in almost all areas of technology, and optical chemical sensors offer several advan- tages over conventional devices in a wide range of applications including process control, and environmental and biomedical fields. Optical sensors are electronically passive and are not subject to electrical and electromagnetic interferences. They are also tlexible, easily miniaturized, inexpensive and of rugged construction.They can be corrosion resistant and are * Prcsentcd at the Scnsors and Signals Symposium at The Royal Society of Chemistry Autumn Meeting, Dublin, Ireland, September 16-18, 1992. capable of real-time monitoring of samples. As they are non- electrical, optical sensors are intrinsically safe and capable of operation in hostile environments. Referencing can be carried out optically and internally and, unlike potentiometric sensors, they do not require a separate system. The use of low optical loss fibres in sensors allows transmission of optical signals over distances of up to about 1 km, and this makes them useful in remote sensing applications. Substantial economic advantages are provided by these sensors due to the possibility of multiplexing several sensors to a single, often costly, instrumentation.As these are small in size, they can be used to measure analyte concentrations without significantly perturbing the sample. Optical sensors can be developed for chemical and biological analytes for which other sensing devices are not suitable or available. Notwithstanding numerous advantages optical sensors also have some disadvantages. Ambient light can interfere with the measurement of optical signals. Therefore, either the sensors must be used in dark environments or the optical signal must be modulated to resolve it from the ambient light. In the latter case, the detector would also be modulated to receive only those modulated optical signals. Long-term stability could be a problem with optical sensors based on the use of indicator phases as a result of photodegradation or leaching effects.These can be compensated to some extent by the use of the ratio of optical signals of two measurement wavelengths. As the chemical indicator and the analyte are in different phases, the consequent mass-transfer step required to achieve chem- ical equilibrium will limit the response times of optical chemical sensors. In general, sensors will have a limited dynamic range of measurement of analyte concentrations. One way this range can be extended would be by the use of multiple sensors that can mcasure different levels of analyte (see Conclusions). Despite a few limitations, optical sensors have the potential to provide an alternative to other sensing systems due to the many advantages these sensors impart in analytical measure- ments.Principle The basic concept of an optical fibre based chemical trans- ducer is simple (Fig. 1). Light from a suitable source is launched into the optical fibre and guided to a region where it interacts with a measurand system or with a chemical318 ANALYST, APRIL 1993, VO12. 118 - Incident I Source I (4 \ Reagent phase I J light To detector Amplifier Readout ( b)/ - Incident light - To detector Lr Fig. 1 Schematic diagram of the principle of an optical fibre chcmical sensor Table 1 Some examples of plain fibre sensors Species Method of detection Ref. - To detector - Incident light / Phenolic compounds Direct ultraviolet cxcitation and measurement of fluorescence 2 Reagent phase Uranium (as U02’+) Direct fluorescence 3 Fig.2 Optical sensors with chemical transducer placed at the cnd of NADH (in bioreactions) Direct fluorescence ( a ) a bifurcated optical fibre bundle and ( b ) a single optical fibre, or (c) coated on the outside of a single fibre (from ref. 5 ) 4 transducer. This interaction results in a modulation of the optical signal, and the modulated light, which is encoded with chemical information, is collected by the same or another optical fibre and guided to a light-measuring system. Depend- ing on the particular measurement device and the optical principles employed, the optical signal measured can be absorbance, reflectance, luminescence or scattering. The chemical transducer usually consists of immobilized reagent(s) that is analyte specific and is often capable of measuring trace levels of analyte.Sensor Design Two types of optical fibre sensing devices for chemical species have been developed. One type, which can be described as a ‘spectroscopic’ or ‘plain-fibre’ sensor, detects the analyte species directly through their characteristic spectral proper- ties. In such devices, the optical fibre functions as a light-guide conveying optical energy from the source to the sampling area and from the sample to the detector. In the sample, the light interacts with the chemical species being monitored (see Table 1, for some examples). In the second type of sensing device, a ‘chemical transducer’ is interfaced to the optical fibre. The analyte species interacts with the transducer, whose modified optical properties are monitored through the optical fibre.This type of device is the more common one, because a large number of analytical species are themselves colourless or non-luminescent. Furthermore, great specificity can be im- parted to these sensors as a consequence of the incorporation of the chemical transduction system. cladding material [Fig. 2(c)]. Hence, the transmission charac- teristics of the optical fibre are modified as a result of the change in the refractive index of the coating when the reagent in the transducer undergoes changes in optical characteristics owing to its interaction with the analyte. Such devices employ the principle of the evanescent wave technique. For plain-fibre sensors, the configuration of the optical fibre can be either as shown in Fig.2(a) and ( b ) or the fibre can be placed in the transmission mode whereby the length of the fibre is interrupted by an area where the analyte sample comes into the optical view of the fibre.6 As mentioned earlier, the chemical transducer consists of immobilized chemical reagents, which are normally analyte specific. The reagent systems are often employed in the solid phase for convenient handling. The reagent phase is localized in the sensing region of the optical fibre either by direct deposition on the fibre or by encapsulation with a polymeric membrane. Immobilization of chemical reagents can be carried out either physically or chemically.” The physical methods of immobilization include gel entrapment, adsorp- tion and electrostatic attraction, and use simple and econ- omical procedures. Chemical immobilization is based on the formation of a covalent bond between the reagent molecule and an activated or functionalized form of the polymeric solid support.This method is the most irreversible of the immobi- lization techniques, but requires several steps in the synthesis of the immobilized reagent phase. The simplest type of optical chemical transducer uses a single step reaction between the reagent phase and the analyte species, and a number of optical sensors studied to date have The interaction between the light and the analyte takes ciearly demonstrated this- approach. A more complicated place at one end of the optical fibre. A variety of transducer transducer might use a multi-step reaction to produce a configurations has been employed in the sensing region.measurable optical signal. However, this type of device is Transducer based sensing devices can involve the use of either normally more difficult to implement in practice. The present bifurcated optical fibre bundles or single optical fibres5 as range of optical sensors tends to be more chemically or shown in Fig. 2. In bifurcated optical fibre based sensors, biochcrnically specific, because so much indicator chemistry i s separate fibres are employed to transmit incident and detected available for adaptation into this promising new technology. optical radiation. However, in single optical fibre based Chemistry of Sensor Response sensors, it will be necessary to distinguish between the incident and detected radiation.In both types of designs, the chemical transducer is placed at the distal end of the optical fibre [Fig. The sensor response function in optical chemical sensors 2(a) and ( b ) ] . With single optical fibres, the chemical depends on the manner in which the analyte interacts with the transducer can also be a coating on the surface of the fibre as a reagent phase with the chcmical transducer. For example, aANALYST, APRIL 1003, VOL. 118 319 reagent (R) reacting with an analyte species (A) forming a product (AR) can be represented as A + R G A R (1) Here, either R or AR is usually absorbing or luminescent, and can therefore be measured optically. The reagent employed is usually selective, producing a distinct optical change for the given analyte species.The chemical transduction is normally based on the equilibrium established during the chemical reaction between A and R, and this equilibrium can be described as where K is the equilibrium constant and the square brackets indicate the equilibrium concentration of the species involved. During the chemical reaction, the reagent R is consumed and, therefore, any absorbance or luminescence due to it de- creases, or as the product AR forms its absorption or luminescence increases. Either way, the change in optical property of R or AR can be related to their concentration and, in turn, related to the concentration of the analyte A causing changes in the measured optical property. These are described below. If the reagent is consumcd during the reaction, then its total initial concentration (cR) at any time will be given by CK = [AR] + [R] (3) Thus, from eqns.(2) and ( 3 ) , the analyte concentration can be expressed as [ A ] = p 1 (G- 1) (4) If the optical property of AR is being measured then the analyte concentration can be rclated to the concentration of AR The concentrations of R in eqn. (4) and of AR in eqn. (5) are related to the measured optical property. The reaction represented in eqn. (1) is a reversible one and thus provides sensing with a direct indicator, which requires an appropriate equilibrium constant for the desired analyte concentration range. The sensor response also depends on the total amount of the indicator. Furthermore, any uncontrolled variable that affects the equilibrium constant will be a potential source of error.For example, for any reaction involving ions, variations in ionic strength will affect the K values. If the measured optical parameter is dependent on the ratio of the concentrations of the two forms of the indicator, i.e., [AR]/[R], then the response no longer depends on the total amount of the indicator, although the dependence on the equilibrium constant remains. Indicator reactions are most familiar to the analytical chemist in the context of titration procedures and indicator strips commonly used for semi-quantitative estimation of pH. The concentration of indicator is much lower than that of the analyte so that there is no perturbing effect in the sample. For example, in optical pH sensing, there is a multitude of pH indicators with different K values.Therefore, it will be relatively easy to find a pH indicator to cover virtually any desired pH range. Because of its importance, the theory and practice of optical pH sensing has been the subject of a critical study by many workers. Indicators showing reversible reactions with analytes are generally preferred for use in optical sensors because they can provide continuous and unperturbed measurements. The equilibrium response of indicators does not depend on mass transfer; however, the response time (ie., the time required to reach the equilibrium) is dependent on mass transfer. Revers- ible interactions of analytes with indicators, which do not involve chemical reactions, can provide short response times.For example, the optical oxygen gas sensor based on the dynamic quenching of fluorescence of an indicator does not involve a chemical reaction .7,8 The fluorescence quenching effect takes place by energy transfer from indicator to the oxygen molecules when they are in contact, and there is no consumption of oxygen. However, there are only a few examples known of fully reversible analyses and sensing by optical measurements. Many reagent phases can be regener- ated after reaction with analytes. For cxample, the lead sensor based on immobilized dithizone can be regenerated with HCP whereas the aluminium sensor based on immobilized Erio- chrome Cyanine R can be regenerated using fluoride solution (Fig. 3).*() Measurements of the ratio of optical intensities at two wavelengths can be used to determine the analyte concentra- tion.Such ratio measurements are inherently more stable with respect to drift. One of the main advantages of the optical sensing approach to chemical measurements is the possibility of developing sensors with long-term stability with respect to calibration because they can be based on ratio measurements. Hence, eqn. (2) can be rearranged to As mentioned earlier, the ratio [AR] : [R] is independent of the amount of indicator. Hence, it should be possible to design ‘precalibrated’ sensors based on ratiometric intensity measurements, and the analysis can be performed directly. Most chemical sensors reported to date involve the use of indicators, and some examples are illustrated in Table 2, according to the type of reaction involved.As can be inferred, most indicator reactions involve a ground-state interaction with analyte, except in the luminescence quenching reaction, where the interaction occurs in the excited state. I - Time Fig. 3 Response of immobilized Eriochrome Cyanine R to alumi- nium ions in solution (A) and its regeneration using fluoride solution (B) Table 2 Direct indicators in optical sensors Type of reaction Analyte Acid-base p” co2 NH3 Complexation Pb2 + AP+ Ligand exchange H20 (vapour) Luminescence quenching O2 0 2 so2 Halidcs Halocarbons Ref. I I , 12,13 14 15, 16 9 10,17 18 19 7 , s 20 21 22320 ANALYST, APRIL 1993, VOL. 118 The use of irreversible chemical reactions in the develop- ment of optical sensors will result in ‘one shot’ devices that can be used only once and which must then be disposed of.Although there will be limited merit in using such reactions in fibre optic chemical sensors, they can provide high sensitivity of measurements. However, the reagent phases have to be prepared with sufficient reproducibility so that the response will be the same from sensor to sensor. Otherwise, the sensor cannot be satisfactorily calibrated. If the irreversible reagent phases are formulated as flat strips or slides, then it might be possible to achieve the necessary reproducibility in measure- ments. The reaction involved in an irreversible sensor can be represented as A + R + A R (7) Such reactions proceed towards completion, are indepen- dent of the equilibrium constant and measure the total amount o f analyte.The sensor response will be dependent on mass transfer. Examples of such sensors include those for sensing H2S’3 and CI2.2-‘ Indirect indicators have been studied for use in optical chemical sensors, which include two or more reagent com- ponents, whose interaction varies with the concentration of thc analyte. The interaction can be represented as in eqn. (1) or as R + S S R S (8) where S is the species that competes with A for the reagent R. In the absence of A, the reaction in eqn. (8) will proceed to the right. As the concentration of A increases in the sample, the reaction in eqn. (1) proceeds to the right and the reaction of eqn. (8) proceeds to the left, resulting in free S. The optical characteristics of S can be measured as a function of the concentration of A.Such interactions are referred to as ‘competitive binding reactions’ and have been used in t h e development of an optical glucose sensor based on immobi- lized Concanavalin A and fluorescein labelled dextran .Z5 In general, indirect indicators offer the potential of varying the effective equilibrium constant, which in turn determines the range of concentrations to which the sensor responds. This is n o t possible with direct indicators. In addition to the different types of chemical interactions discussed above, there are other phenomena such as catalysis, with which chemical species could be sensed by optical means. These are not discussed here. Optical Techniques The optical sensing of chemical species is based on their interaction with light. In optical chemical sensors, three of the optical techniques commonly employed for measurements are the absorption, emission and reflection or scattering of light.The quantitative aspects of the use of these optical phenomena are briefly discussed here, together with a brief explanation of thc phenomena for completeness. Absorption Absorption of optical energy gives rise to transitions in the electronic, vibrational and/or rotational energy states of the atoms and molecules, and occurs only if the difference in the energy states involved matches exactly the energy of the exciting photons. Visible and ultraviolet radiation induces electronic excitation, infrared radiation promotes vibrational excitation, and microwave radiation gives rise to rotational transit i ons .Absorption leads to a diminution of the power of the radiation as it passes through the sample. Therefore, after encountering a number of absorbing species, a light beam of initial intensity I(, will be transmitted by the sample with a reduced intensity I . It should be recognized that only those frequencies that are absorbed will be attenuated, and all other frequencies will pass through with no power loss. The decrease in the light intensity is determined by the number of absorbing species in the light path, and is related to the concentration, c , of the absorbing species through the Beer-Lambert equation A = log/o/I = EIC (9) where A is the absorbance, I is the length of the light path and E is the molar absorptivity, which is characteristic of the analyte substance at a given wavelength.Luminescence The absorption of energy from a photon causes atoms or molecules to be promoted to a higher energy state. However, the excited species is short-lived and releases its extra energy via several pathways. One of thc relaxation modes involves luminescence, wherein radiation of a lower frequency is emitted. Deactivation through luminescence can occur either from a singlet state, in which case the emission is called fluorescence, or from a triplet state, in which case the emission is called phosphorescence. Fluorescence is extremely rapid and occurs within 1-100 ns after excitation. On the other hand, phos- phorescence has a longer decay period (1-1000 ps) and persists after the removal of the excitation source.In both cases, the emitted radiation is of a different frequency to that of the exciting radiation, and its intensity, I[_, is dependent on the intensity of the exciting radiation, lo, and the concentration, c , of the luminescent species. For weakly absorbing species, i.c., A <0.05, the intensity of luminescence can be expressed by the following equation ( 10) I L = k’1(+3Elc where 1 is the length of the light path in the sample, E is the molar absorptivity, 0 is the quantum efficiency of the luminescence and k’ is the fraction of the emission that can be measured. At constant lo, eqn. (10) can be simplified to I , = kLC (11) where kL = k’IoOd. In the presence of some species (e.g., oxygen), the luminescent decay of an activated species could compete with a collisional quenching decay mode. The mean lifetime of the activated species is decreased and the luminescence intensity is reduced.In this case, the luminescence intensity, IL, is related to the concentration of the quenching species, cq, by the Stern-Volmer equation P / I L = 1 + Ksvcq ( 12) where I0 is the luminescence intensity in the absence o f the quencher and Ksv is the Stern-Volmer constant. An excited species can also be generated through a chemical reaction. The measured light that is emitted as the excited species returns to the ground state is then known as chemilumineseence, which can be quantitatively related to the concentration of the analyte species. Reflectance Reflection takes place when light strikes a boundary surface. Two distinct processes are responsible for this.The first is the mirror-type or specular reflection, which occurs at the interface of a medium with no transmission through it. The other type is diffuse reflection, wherein the radiation pene- trates and subsequently reappears at the surface of the system following partial absorption and the multiple scattering within the system. These two processes are complementary, but specular reflection can be eliminated or minimized through proper sample preparation or optical engineering.ANALYST, APRIL 1993, VOL. 118 Recorder/ display 32 1 . Lock-in amplifier Diffuse reflectance has been recognized to be dependent on the composition of the system, analogous to light absorption. Several models for diffuse reflectance have been proposed based on the radiative transfer theory, which considers all incident light to be light scattered by other particles.The most widely used model is the Kubelka-Munk theory. Here, a thick semi-infinite scattering layer is assumed and reflectance, R , is related to the concentration, c , of the absorbing species on the scattering layer through the molar absorptivity, E, and the scattering coefficient S , as follows: F(R) = ( 1 - R)'/2R = €CIS (13) where F(R) is known as the Kubelka-Munk function. Instrumentation The basic instrumentation associated with optical fibre sensors is simple and requires both optical and electronic components. A typical instrumentation system employed in conjunction with optical sensors is shown schematically in Fig. 4. Apart from the fibre, it consists of a light source, photodetector, optical couplers and monochromators, modulator, signal amplifier and readout.The source of illumination must be able to provide an intense and stable radiation. Several types o f light source have been employed in optical chemical sensors, viz., incandesccnt lamps, gas lasers, light-emitting diodes (LEDs) and semicon- ductor injection lasers. Incandescent sources, such as tungsten lamps and quartz-halogen lamps, emit a broad spectrum of optical radiation and are used as sources of ultraviolet and visible light in short-range optical fibre sensors. Gas lasers are useful general purpose sources of highly intense and coherent radiation and are employed in long-distance (remote) sensing systems. The LEDs and injcction lasers are miniature sources of high-intensity monochromatic radiation; they produce incoherent light with a spectral bandwidth of 40---50 nm and are useful in short range fibre optic sensing (up to 1 km).On the other hand, injection lasers radiate a coherent beam of light with narrower spectral bandwidth (5-1 0 nm) and are excellent sources for transmission of light in fibres of greater lengths. The photodetection system is essentially a photon-counting device, where optical signals arc converted into electrical signals, which can be easily amplified by electronic means. The photodetector must possess a peak sensitivity at the mcasuremcnt wavelength, must generate a minimal amount of noise to the transmitted signal and must respond rapidly to variations in intensity of the incident light.Various types of photodetectors have been incorporated in optical chemical sensors. These include photomultiplier tubes, positive intrin- sic negative (PIN) photodiodes, photodiodc arrays and avalanche photodiodes. Optical couplers are required to focus the light beam to the optical fibre and also direct radiation from the return fibre to the photodetector. Focusing light from a source into an optical fibre is a more tedious operation. Laser sources produce a coherent beam of light with a cross-section almost equal to the cross-sectional area of the fibre, and can therefore be coupled signal source modulator c h romator Detector Fig. 4 used in conjunction with an optical fibre chemical sensor Schematic diagram of a typical and simple instrumental set-up very effectively to an optical fibre.On the other hand, LEDs and incandescent lamps radiate divergent beams of light and require lenses to focus their optical output onto the fibre. The coupling of the photodetector to the optical fibre is more easily accomplished, as the detectors have relatively large active surface areas and large acceptance angles. However, before the light is led to the photodetector, Wavelengths other than that relating to the species of interest have to be excluded. Optical resolution has to be carried out if illumination is provided by an incandescent source or an LED. Isolation of the desired wavelength can be achieved through filters or monochromators. Simple optical filters attenuate the light significantly and could reduce the sensitivity of the optical system.Monochromators offer high efficiency and can be adapted for different wavelengths. As mentioned earlier, ambient light can interfere with the measurement by gaining entrance into the sensing region of thc optical fibre. This intcrference could be eliminated by maintaining the sampling area in a dark environment, protected by a light-tight covering, or by modulating the light source so that optical sign& derived from it can be differen- tiated from an extraneous radiation. The electronic components of the instrumentation could suffer from drift during the course of operation. For instance, the intensity of the light source can vary due to ageing or due to fluctuations in the power supply unit. The effect of these variations can be eliminated by the use of internal referencing, which involves monitoring a radiation that is not altered during the sensing process.Applications Optical fibres have been used in chemical and biochemical analyses for the transmission of optical signals both with and without chemical transducer attached. Whereas in the latter (plain fibre sensor) type the analyte itself possesses some measurable optical property, in the former (chemical trans- ducer based) type, the analyte interacts with the immobilized reagent producing a change in the optical property of the reagent. The latter type is the most commonly employed design in many optical fibre chemical and biochemical sensors because many analytes themselves do not possess measurable optical properties.In the plain fibre sensor type devices, optical fibres are normally constituted as part of the instrumentation in many commercially available systems, which are intended for use in fermentation systems, bioreac- tors, explosive atmospheres, river and reservoir monitoring, etc. The chemical transducer based optical sensor allows a much wider range of application and is of potential use in all types of analytical sciences. Typical areas are pollution and process control , biotechnology , environmental and atmos- pheric monitoring, clinical analysis, defence, water analysis, etc. Many such applications have been comprehensively reviewcd".'6.'7 and it is not intended to discuss them here; the reader is advised to source the literature as required. Conclusions Optical fibres have induced a renaissance of optical methods of chemical analysis.By its combination with suitable instrumentation , optical chemical sensors can be developed. The basic instrumentation associated with optical sensors is simple and requires only standard components, which are well advanced in their state-of-the-art. Hence progress in this field of optical sensors will be dependent on the development of appropriate reagent phases for the transducer. Ideally, optical sensing devices should be characterized by high sensitivity, selectivity and reliability. Furthermore, the ability to perform measurements in real-time, in a site-specific fashion and on a continuous basis, would be more important in322 ANALYST, APRIL 1993, VOL. 118 * Y .- ! l o _ 2 9 6 7 8 9 10 11 Fig.5 Comparison of reflectance rcsponsc of a twin-probc optical pH sensor (Bromocrcsol Purplc + Bromothymol Blue) with the responsc o f a pH electrode mctcr (correlation coefficient = 0.9998) Electrode pH meter [pH] the application of these sensors to practical analysis problems. The concept of multi-sensors for the simultaneous detection of scveral species has begun to attract considerable interest. For example, optical fibre sensors for in vivo continuous measure- ments of pH, oxygen and carbon dioxide have been bundled into a single probe, for use in medical diagnostics,28 with a view to insertion via catheters. The problem of limited dynamic ranges could be addressed with the use of multi-sensors capable of measuring different concentration levels of analyte.For example, the dynamic range of pH measurements can be extended from 2 pH units with a single sensor to about S pH units using a twin-sensor probe (Fig. S).'9 Several chemical reactions have been adapted in the development of optical sensors. In many cases, the sensors have been selective and sensitive to specific analytes, and the motivation for devcloping optical chemical sensors is thus established. I t is likely that such development will continue to be a very active area of analytical research. This development also requires expertise from several areas including indicator/ reagent synthcsis, polymer chemistry, biochemistry, ana- lytical spectroscopy, fibre optics and optoelectronics, because optical chemical sensors require an interdisciplinary approach to enhance growth in this area.References 1 Kautsky. H., and Hirsch, A., Z. Anorg. Allg. Chem., 1935,222, 126. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Chudyk, W. A., Carrabba, M. M., and Kenny, J. E., Anal. Chem., 1985,57, 1237. Klainer, S., Hirschfeld, T., Bauman, H., Milanovich, F., Perry, D., and Johnson, D., Annuul Report, LBL 11081, Lawrcnce Bcrkelcy Laboratory, CA, 1981. Wolfbeis, 0. S . , in Sensors in Bioprocess Control, cds. Twork, J . \'., and Yacynych, A. M., Marccl Dekkcr, New York. 1990. Narayanaswamy, R., Anal. Proc., 198.5, 22, 204. Narayanaswamy, R., and Sevilla, F., 111, J . Phys. E, 1988, 21. 10. Pcterson, J . I . , Fitzgcrald, R. V., and Buckhold, D. K., Anal. Chem., 1984, 56, 62. Li, P. Y . F., and Narayanaswamy. R.. Anulyst, 1989, 114. 1191. de Oliveira, W. A., and Narayanaswamy, R., Tulanta. 1092,39, 1499. Ahmad, M. B . , and Narayanaswamy, R., unpublishcd work. Pcterson, .l. I., Goldstein. S. R., Fitzgerald, R. V., and Buckhold. D. K., Anal. Chem., 1980. 52, 864. Saari. L. A . , and Seitz, W. R., Anal. Chem., 1982, 54, 821. Kirkbright, G. F., Narayanaswamy, R., and Wclti, N. A . , Anulysr, 1984, 109, 1025. Zhujun, Z., andSeitz, W. R.,Anal. Chim. Actu, 1984, 160,305. Giuliani, J . F., Wohltjcn, H., and Jarviq, N . L., Opt. Left., 1983, 8 , 54. Caglar, P., and Narayanaswamy, R., Anulyst, 1987, 112, 1285. Saari, L. A., and Seitz, W. R., Anal. Chem., 1983, 55, 667. Russell, A. P., and Fletcher, K. S . , Anal. Chim. Actu, 19x5, 170, 209. Zhujun, Z., and Seitz, W. R . , Anal. Chem., 1984, 56, 220. Wolfbcis, 0. S., and Sharma, A . , Anal. Chim. Acta. 1988, 208, 53. Urbano. E., Offcnbacher. H., and Wolfbeis, 0. S . , And. Chem., 1984, 56, 427. Wolfbeis, 0. S . , Posch, H. E., and Kroncis, H. K . , Anal. Chem., 1985, 57, 2556. Narayanaswamy, R., and Sevilla F., 111. Fresenius' 2. Anal. Chern.. 1988, 329, 789. Momin, S . A., and Narayanaswamy. R., Anal. Chim. Acfa, 1991, 244, 71. Schultz, J. S . , Mansowi, S . , and Goldstcin, I . J . , Diubetes Cure, 1982, 5 , 245. Seitz, W. R., CRC Crit. Rev. Anal. Chem.. 1988, 19, 135. Wolfbeis, 0. S., Fiber Optic Chemical Sensors and Biosensors, CRC Press, Boca Raton, 1991, vols. I and 11. Gehrich, J. L.. Lubbers, D. W., Opitz, N . , Hansmann, D. K., Miller, W. W., Tusa, J . K., and Yasufo, M., IEEE 7runs. Biomed. Eng., 1986, BME-33, 117. Guestrin, H. R., and Narayanaswamy, R., unpublishcd work. Paper 210.57188 Received October 27, I992 Accepted November 5, I992

ISSN:0003-2654    

DOI:10.1039/AN9931800317

出版商:RSC    

年代:1993

数据来源: RSC