摘要:

Proceedingsof the Analytical Division ofThe Chemical Society19319619819920920921 021 221 221 4CONTENTSNew Officers and Members of CouncilRegional Advisory Editors of The AnalystReports of MeetingsFourth Theophilus Redwood LectureSummary of Paper"Elwell Award Meeting"Conferences and MeetingsSilver MedalPublications ReceivedReprints of Review PapersVolume 12 No 7 Pages 193-214 July 197PADSDZ 12(7)193-214(1975)ISSN 0306-1 396PROCEEDINGSOF THEJuly, 1975ANALYTICAL DIVISION OF THE CHEMICAL SOCIETYOfficers of the Analytical Divisionof the Chemical SocietyPresidentG. W. C. MilnerHon. SecretaryP. G. W. CobbSecretaryMiss P. E. HutchinsonHon. Treasurer Hon. Assistant SecretariesJ. K. Foreman D. I. Coomber, O.B.E.; D.W. WilsonEditor, ProceedingsP. C. WestonProceedings is published by The Chemical Society.Editorial: The Director of Publications, The Chemical Society, Burlington House, London, W1V OBN.Telephone 01 -734 9864. Telex 268001.Subscriptions (non-members): The Chemical Society, Publications Sales Office, Blackhorse Road, Letch-worth, Herts., SG6 1 HN.Non-members can only be supplied with Proceedings as part of a combined subscription with The Analystand Analytical Abstracts.@ The Chemical Society 1975ANALYTICAL SCIENCES MONOGRAPHNo. IHigh- Precision Titrimetryby C. Woodward and H. N. RedmanImperial Chemical Industries Limited (Agricultural Division)BRIEF CONTENTS:IntroductionVisual Titrations, with sections on Apparatus, Standard Substances and their preparation andInstrumental Methods, with sections on Photometric Titrations, Electrometric Titrations andReferences to the literature of high-precision titrimetry.assay, and Standard Solutions.Miscellaneous Techniques.Price f 2.50Obtainable from :The Publications Sales Officer,THE CHEMICAL SOCIETY,Blackhorse Road, Letchworth, Herts, SG6 1 H NMembers may buy personal copies at the special price of f2.00 provided they orderdirect and enclose remittancePp. viii+63 ISBN 0 85990 501

ISSN:0306-1396    

DOI:10.1039/AD97512FX024

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

Reprints of Review PapersReprints of the following Review Papers published in The Analyst since 1964 are available fromThe Chemical Society, Publications Sales Office, Blackhorse Road, Letchworth, Herts. SG6 1HN(not through Trade Agents).The price per reprint is Sop; orders for four or more reprints of the same or different Reviewsare subject to a discount of 25 per cent. The appropriate remittance, made out to TheChemical Society, should accompany any order.“Some Analytical Problems Involved in Determining the Structure of Proteins and Peptides,”“The Faraday Effect, Magnetic Rotatory Dispersion and Magnetic Circular Dichroism, ” by“Electrophoresis in Stabilizing Media,” by D. Gross (July, 1965).“Recent Developments in the Measurement of Nucleic Acids in Biological Materials,” by“Radioisotope X-ray Spectrometry,” by J .R. Rhodes (November, 1966).“The Determination of Iron(I1) Oxide in Silicate and Refractory Materials,’’ by H. N. S.“Activation Analysis,” by R. F. Coleman and T. B. Pierce (January, 1967).“Techniques in Gas Chromatography. Part I. Choice of Solid Supports,” by F. J . Palframan“Heterocyclic Azo Dyestuffs in Analytical Chemistry,” by R. G. Anderson and G. Nickless“Determination of Residues of Organophosphorus Pesticides in Food,” by D. C. Abbott and“Radioactive Tracer Methods in Inorganic Trace Analysis: Recent Advances,” by J . W.“Gamma-activation Analysis,” by C. A. Baker (October, 1967).“Precipitation from Homogeneous Solution,” by P. F. S. Cartwright, E. J . Newman and“Industrial Gas Analysis,” by (the late) H.N. Wilson and G. M. S. Duff (December, 1967).“The Application of Atomic-absorption Spectrophotometry to the Analysis of Iron and“Inorganic Ion Exchange in Organic and Aqueous - Organic Solvents,” by G. J. Moody and“Radiometric Methods for the Determination of Fluorine,” by J. K. Foreman (June, 1969).“Techniques in Gas Chromatography. Part 11. Developments in the van Deemter RateTheory of Column Performance,” by E. A. Walker and J. F. Palframan (August, 1969).“Techniques in Gas Chromatography. Part 111. Choice of Detectors,” by T. A. Gough andE. A. Walker (January, 1970).“Laser Raman Spectroscopy,” by P. J. Hendra and C. J. Vear (April, 1970).“Ion-selective Membrane Electrodes,” by Ern0 Pungor and KlAra T6th (July, 1970).“X-ray Fluorescence Analysis,” by K.G. Carr-Brion and K. W. Payne (December, 1970).“Mass Spectrometry for the Analysis of Organic Compounds,” by A. E. Williams and H. E.“The Application of Non-flame Atom Cells in Atomic-absorption and Atomic-fluorescence“Liquid Scintillation Counting as an Analytical Tool,” by J. A. B. Gibson and A. E. Lally“The Determination of Some 1 ,kBenzodiazepines and Their Metabolites in Body Fluids,”“Atonic-fluorescence Spectrometry as an Analytical Technique,” by R. F. Browner(October, 1974).“The Use of Precipitate Based Silicone Rubber Ion-selective Electrodes and Silicone RubberBased Graphite Voltammetric Electrodes in Continuous Analysis,” by 2s. Fkher,G. Nagy, K. T6th and E. Pungor (November, 1974).“The Examination of Meat Products with Special Reference to the Assessment of the MeatContent,” by D. Pearson (February, 1975).“Chemiluminescence in Gas Analysis and Flame-emission Spectrophotometry, ” by J . H.Glover (July, 1975).by Derek G. Smyth and D. F. Elliott (February, 1964).J. G. Dawber (December, 1964).H. N. Munro and A. Fleck (February, 1966).Schafer (December, 1966).and E. A. Walker (February, 1967).(April, 1967).H. Egan (August, 1967).McMillan (September, 1967).D. W. Wilson (November, 1967).Steel,” by P. H. Scholes (April, 1968).J . D. R. Thomas (September, 1968).Stagg (January, 1971).Spectroscopy,” by G. F. Kirkbright (September, 1971).(October, 1971).by J. M. Clifford and W. Franklin Smyth (May, 1974).Printed by Heffers Printers Ltd Cambridge Englan

ISSN:0306-1396    

DOI:10.1039/AD97512BX026

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

Vol. 12, No. 7 July, 1975 of the Analytical Division of the Chemical Society New Officers and Members of Council Honorary Secretary Mr. P. G. W. Cobb, the new Honorary Secrc- tary of the AD, first became associated with the activities of the SAC when exercising his “privilege” as a member of the RIC to attend meetings of other scientific societies. The variety and interest of meetings held in the Mason College of the University of Birmingham by the Midlands Region of the SAC ensured his regular attendance and eventually led to an invitation by Dr.W. T. Elwell for him to join the Society in 1958. He became a member of the local committee in 1964 and served there- after as ordinary member, Assistant Secretary and Chairman until he left the Midlands region in 1972.He was Assistant Treasurer for the 1969 Birmingham Symposium and at present he is serving as Minutes Secretary on the local com- mittee organising the AD Conference in Birm- ingham in 1977. He served as a member of Council ex oficio from 1970 to 1972 and as an elected member from 1973 to 1975, during which time he was a member of the Programmes and Finance Committees. He is at present a mem- ber of the Microchemical Methods Group Com- mittee and a past member of the Special Tech- niques Group Committee.Born, like Mr. Shaw, the retiring Honorary Secretary, in Nottingham, he was educated a t Cottesmore Senior Boys’ School there and started his career as a clerk in a Chartered Accountants office. Developing a previously undetected interest in science and crime, he changed his job and became a laboratory assistant a t the East Midland Forensic Science Laboratory at Notting- ham in 1946.He has spent the whole of his scientific career in the Forensic Science Service, being transferred to the West Midland Forensic Science Laboratory a t Birmingham in 1954, where he remained until he was appointed to his present position as Director of the Home Office Forensic Science Laboratory a t Aldermaston in 1972.Educated in succession by correspond- ence course, at Nottingham and District Technical College and the Birmingham College of Technology, he passed the ARIC examination in 1956 and obtained the RIC Postgraduate Diploma in General Analytical Chemistry (Branch A) in 1960. He obtained a Diploma in Government Administration in 1964.In the course of his career as a forensic scientist, he has been concerned with a wide variety of investigations ranging from murder by poisoning to stealing from gas meters, and these have entailed his appearance in most types of legal proceedings. The close contact with police officers and the legal profession that this type of work involved has added consistently to the satisfaction of his chosen career. He lives at Pamber Heath, Hampshire, with his wife and two sons, and they have all found their deposition amongst the,”insular” southern- ers to be a most pleasurable experience.Vice-president Mr. W. H. C. Shaw, a new Vice-president of the Division, retired at the Annual General Meetings in March as Honorary Secretary of the SAC and of the AD after completing a 7-year period of service. Throughout this time, he took an active part in the administration of the SAC, and latterly of the AD in the 3-year trial amalgamation period since the formation of the “new” Chemical Society in 1972.He served as one of the SAC negotiators for two periods, in the initial amalgamation negotiations with the CS in 1971 and again before the completion of amalgamation in 1974.As an Honorary Officer, an ex oficio member of all Committees of Council, a representative of the SAC/AD on CS MY. P. G . IY. Cobb. MY. W. H . C . Shaw. 193194 NEW MEMBERS OF COUNCIL Proc. AnaZyt. Div. Chem. SOC. Council and for a time on the then CS Inter- divisional Committee, on the Analytical Chem- istry Sub-Committee of the British National Committee for Chemistry and on the Parlia- mentary and Scientific Committee, as a Trustee of the Analytical Methods Trust, a member of the Advisory Sub-committee of the SAC Analytical Chemistry Trust and, occasionally, as a secre- tary, his time in office was always challenging, usually exciting and normally busy.He counts it as one of his greatest privileges to have been close to the centre of SAC affairs over one of the most eventful periods of its history, culminating in the Centenary Celebrations in 1974 and its new role as the CS Analytical Division.It was in 1954 that, with the late Mr. A. L. Bacharach as mentor, Mr. Shaw first became interested in the activities of the SAC as an abstractor for Analytical Abstracts. He joined the SAC a year later and subsequently served for 2 years on the Committee of the Biological Methods Group.In 1960, a developing interest in the automation of analysis led him to take an active part in the formation of the Automatic Methods Group and he became the first Honor- ary Secretary of the Group a t its inaugural meeting towards the end of 1965. Elected to Council in 1966, he was appointed in the follow- ing year as Honorary Assistant Secretary (Pro- grammes) and in 1968 as Honorary Secretary upon the retirement from office of Mr.S. A. Price. Born in Nottingham, Mr. Shaw was educated a t Bishop’s Stortford College and the then Uni- versity College of Nottingham. In 1939, he be- came a member of the Pharmaceutical Society and was elected a year later to what has since become the Fellowship of that Society.He subsequently joined the analytical staff of the then Boots Pure Drug Co. Ltd. and in 1945 moved to the Dyestuffs Division of Imperial Chemical Industries ,Ltd. Since 1950, he has been Head of Analytical Research in Glaxo Laboratories Ltd. , although latterly in Glaxo Research Ltd. as a result of reorganisation carried out in 1973.In 1942, he became an Dv. D. T. Burns. Mr. F. E. Harfier. Associate of the RIC, a Fellow in the special branch of Pharmaceutical Analysis in 1947, in the Chemistry of Food, Drugs and Water (M.Chem.A.) some 4 years later, and was subse- quently awarded the M.Pharm.A. He has published papers and .reviews in the fields of pharmaceutical, microbiological and automatic analysis and recently contributed chapters to the second edition of “Analytical Microbiology.” He currently serves on the Committee of Management of the Joint Pharmaceutical Analysis Group, on the inaugural Committee of the South East Region of the AD and as a mem- ber of the Review Committee responsible for general methods of analysis for the British Pharmacopoeia 1978.He is married with two sons, and finds that the demands of a large garden and numerous furred and feathered dependents leave little time for his other leisure interests of golf , swimming and photography.Duncan Thorburn Burns was born in Wolverhampton and, after an early itinerant education in Rugby, Manchester, Wolver- hampton and Newton Stewart, arrived in Gomersal, where he almost became a Yorkshire- man but failed to develop the requisite devotion to cricket.After leaving Whitcliffe Mount Grammar School, he undertook the course known at that time as “Special Studies in Chemistry” at Leeds University, graduated in 1955 and stayed on to do research in physical chemistry and obtained a PhD in 1959. His first appointment was to Medway College of Technology as Assistant Lecturer in Physical Chemistry in 1958, becoming Lecturer in 1959.In 1963 he joined Woolwich Polytechnic as Senior Lecturer in Analytical Chemistry. Membership of the SAC and a return to the Midlands Region were both effected in 1966, upon appointment to Loughborough University of Technology as Senior Lecturer and Head of the Analytical Chemistry Section. Subsequently he became Reader in 1971 and was awarded a DSc by the University in 1972.He has been a Committee Member of the Microchemical Methods Group and the Midlands Region and is currently Vice-chairman of the Education and Training Group and Chairman of the Midlands Region. Due to appointment to QueenJs University of Belfast, it will not be possible to complete the normal term of this last office but he hopes to continue in the Region’s traditions across the water.Frank Harper was born in the Cleveland district of North Yorkshire and, following his earlier education at the Middlesbrough HighJuly, 1975 NEW MEMBERS OF COUNCIL 195 School, had the good fortune to obtain his initial training in analytical chemistry in the late H. N. Wilson’s department at ICI, Billingham. He passed the external London Intermediate BSc examination in June, 1939, and spent the next 64 years in the RAMC, eventually reaching the rank of Staff Sergeant in the Department of Pathology in an East African Military General Hospital.Returning to Billingham, he worked under the direction of Albert Smales until a grateful government financed the completion of his degree course at Durham University.After graduating in June, 1949, he did not rejoin his old friends in the Analytical Depart- ment, but during a visit to the Middlesbrough General Hospital Pathology Department he was offered the post of Senior Biochemist to the Teesside Group of Hospitals. Despite the fore- bodings of a Billingham Director that he would never make it in clinical chemistry, he took up the post in January, 1950, and is still trying hard to prove the gentleman wrong.He became a Fellow of the RIC in 1959 and was recently awarded the Fellowship of the Royal College of Pathologists. He is happily married with one son. Mr. A. W. Hartley was educated at Christ’s Hospital and Manchester College of Technology, where he obtained the qualifications AMCT and ARIC. He has been in the food industry during the whole of his career and was elected FRIC in 1954.He has been employed by Spillers Limited for 33 years and now holds the position of Group Chief Analyst at their Research and Technology Centre, Cambridge. His main field of interest has always been in food analysis and he has published a number of papers on analytical methods, nutrition and the design of equipment, including the Hartley funnel, now unfortunately no longer marketed. Mr.Hartley has served on the Chemical Society Mid-Anglia Section Committee and is at present Chairman of the East Anglia Region of the Analytical Division. He is married with two daughters and his main hobbies are photography, industrial archaeology and antiquarian horology. W. J. Price started his career as a laboratory assistant with the British Cast Iron Research Association and did “stints” in ’chemical laboratory, mechanical testing and metal- lography. In those days, although the spectro- graph was accepted fairly widely in the steel industry, it had not been applied to the analysis of cast iron, and investigation into this was his first joint research project.During this time he obtained his BSc degree externally at London University. Subsequently he became Spectro- scopist and then Chief Analyst with Magnesium Elektron Ltd. in Manchester, where particular highlights were co-authoring a book on the analysis of magnesium alloys (1955). installing a quantometer (1956) and doing some early experiments on atomic absorption. In 1961, he joined Unicam Instruments Ltd., with the commission of building up an Applica- tions Department.Interest then developed in ultraviolet and infrared spectrophotometry as well as a more serious connection with atomic absorption. He became a founder member of the Atomic Absorption Discussion Group of the SAC, a Committee member, and eventually, in 1969, Chairman of the Group, a t the time when it was decided to change its name and widen its terms of reference to Atomic Spectroscopy.In the same year, he was a member of the Organis- ing Committee of the International Atomic Absorption Conference at Sheffield, which Committee re-united to start the Annual Reports in Analytical Atomic Spectroscopy (with Price as Secretary and Treasurer), which are now into their fourth year of publication by the Chemical Society.MY. A . W . Hartley. ~ r . W . J . Price. Since the merger of Unicam Instruments and W. G. Pye and their incorporation into the Philips Group of Companies, in about 1968, the Application Laboratories a t Pye Unicam were combined and now consist of Inorganic,Organic and Biochemical Sections, the techniques covered including gas and liquid chromatography and electrochemistry as well as ultraviolet, infrared and atomic-absorption spectrometry.The as- pects of work covered by the laboratories are now many and varied, including the solution of customers’ problems, the evaluation of instru- ments and preparation of their methodology be- fore launch on to the market, and the running of training courses and symposia.In 1972, Price’s book “Analytical Atomic Absorption Spectrometry” was published and196 REGIONAL ADVISORY EDITORS OF THE ANALYST Proc. Analyt. Div. Chem. SOC. in the same year he was awarded the DSc degree at London University for work in analytical chemistry and atomic spectroscopy. He has travelled for Pye Unicam to places as far apart as Novosibirsk and Moscow in the USSR, Egypt, the USA and Canada, as well as to most European countries. He lives with his wife, Barbara, at Harlton, near Cambridge, where his time away from the office is occupied with the cultivation of a fairly large garden, and with particular interests such as photography, music and some local activities.Douglas Squirrell was born in Ipswich and educated at the Northgate Grammar School and Sudbury Grammar School.He was first em- ployed at BX Plastics Ltd. at Manningtree, Essex, and worked on analysis and physical testing concerned with production and quality control of cellulose plastics. After a period of service in the Irish Guards, from which he was invalided in 1945, he spent some time in re- habilitation before taking an Honours degree in My. D.C . M . Squawell. chemistry at King’s College London, where he graduated in 1949. He became an Associate of the RIC and was elected to the Fellowship in 1958. Mr. Squirrell has a keen interest in instrumentation and on leaving University, joined the Research Department at ICI Plastics Division. He worked on many aspects of the identification and analysis of plastics and pub- lished several papers on research topics, includ- ing automatic titration and oxygen-flask com- bustion procedures.He is the author and co- author of two books and has assisted in the preparation of the Annual Reports of the Chem- ical Society. He specialised for some years in the applica- tions of X-ray fluorescence spectrometry to the analysis of plastics materials and in 1966 became leader of the analytical research section con- cerned mainly with developments in instru- mental, automatic and on-line analysis.He was appointed Plastics Division Chief Analyst in 1974. Mr. Squirrell joined the SAC in 1955 and has since served on many committees, including that of the Automatic Methods Group as Secretary and Chairman. He is currently Vice-chairman of that Group and a member of the Micro- chemical Methods Group Committee, also serv- ing as a member of the Analytical Methods Committee and the Group Liaison and Policy Committee. Dr. A. Townshend was a Member of Council in 1972-74, and a biography and portrait appeared in Proceedings, 1972, 9, 148. An updated version appeared more ‘recently in Proceedings, 1975, 12, 40, on the announce- ment of the award of the third SAC Silver Medal. J. Whitehead was a Member of Council in 1972-74 and a biography and portrait appeared in Proceedings, 1972,9, 149. Since that time, he served as Chairman of the North East Region in 1973-75, and is currently a member of the North East Region Committee. He is also a member of the Trustees Advisory Committee and Pro- grammes Committee and represents the AD on the Industrial Division Council. In addition to his position as Chief Analyst with Tioxide International, he is managing Technical and Analytical Services, a subsidiary company formed to market the analytical and research facilities of the parent company.

ISSN:0306-1396    

DOI:10.1039/AD9751200193

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

196 REGIONAL ADVISORY EDITORS OF THE ANALYST Proc. Analyt. Div. Chem. SOC. Regional Advisory Editors of The Analyst Newly appointed Regional Advisory Editors for The Analyst are Dr. J. Aggett (University of Auckland, New Zealand), Professor G. Ghersini (Laboratori CISE, Milan, Italy), Dr. I. Rubegka (Geological Survey of Czech- oslovakia, Prague, Czechoslovakia) and Pro- fessor K. Saito (Tohoku University, Sendai, Japan).Biographical notes on Professors Ghersini and Saito are given below. Professor Giovanni G hersini Giovanni Ghersini was born in Milan in 1937. His secondary education was rather adventurous, being scattered among different Italian schools and including also the Canisius High School in Buffalo, N.Y., U.S.A. He obtained his University degree a t the University of Rome.After a short period ofJuly, 1975 REGIONAL ADVISORY EDITORS OF THE ANALYST 197 research in that University, in 1962 he joined Chimica Inorganica (Inorganic Chemistry CISE (Centro Informazioni Studi Esperienze) Society). He joined the SAC in 1971. He is in Milan, a research centre that is interested mainly in nuclear energy, where at present he is Scientific Assistant to the Director of Research Services, and Head of the Chemistry Service.married, with three children. Professor G. Ghersini. His research interests started with solid- state chemical physics, but he soon turned to analytical chemistry, with particular reference to separation by liquid - liquid extraction and chromatographic methods, and to the deter- mination of trace amounts of ions in industrial and natural waters.He has become well known for his work on the extraction chromatography of inorganic ions. At present, he is particularly interested in radiochemistry and in environ- mental problems related to the siting of nuclear power stations. In 1970, he obtained the title of “Free Docent” in Analytical Chemistry, and has been teaching a t the Faculties of Pharmacy and of Sciences in the University of Milan.Professor Ghersini serves on several Com- mittees of the UNI (the Italian Standardisation Organisation, associated with ISO), wkere he is currently the Chairman of the “Precision of Analytical Methods” Group. He is also an Associate Editor of the journal Radiochemical and Radioanalytical Letters. Ghersini is a member of two Italian Learned Societies, namely the Societh Chimica Italiana (Italian Chemical Society) and the Societh di Professor Kazuo Saito Kazuo Saito was born in 1923 in Tokyo, Japan, was brought up in Tokyo and graduated from the Chemistry Department, Faculty of Science, Tokyo Imperial University in 1945.He studied inorganic and analytical chemistry as a Research Assistant at the University of Tokyo (formerly the Tokyo Imperial University) under the super- vision of Professor Kenjiro Kimura, and was awarded his doctorate at the same University in 1952.He studied inorganic chemistry a t the Chem- istry Department of University College London on a Ramsay Memorial Fellowship from 1953 to 1955 under the supervision of Professor Henry Terrey and then Professor Ronald Nyholm.Professor K. Saito. Saito was appointed as an Assistant Professor of Chemistry in the Institute for Nuclear Studies, University of Tokyo, in 1956 and studied inorganic chemistry, especially the preparation of pure radioisotopes and the kinetics of isotopic exchange reactions. He was appointed Professor of Coordination Chemistry in the Faculty of Science, Tohoku University, Sendai, Japan, in 1963 and still holds that Chair. His main studies concern the stereo- chemistry and the reaction kinetics of coordina- tion compounds.198 REPORTS OF MEETINGS Proc. Analyt. Div. Chem. SOC. He has served as an abstractor for Analytical Married since 1953, with one son and one Abstracts since 1954, has been a member of the daughter, his major pastimes are reading out- Chemical Society since 1954 and belongs to many side chemistry and travelling, having so far other learned societies. visited 33 countries of the world.

ISSN:0306-1396    

DOI:10.1039/AD9751200196

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

198 REPORTS OF MEETINGS Proc. Analyt. Div. Chem. SOC. Reports of Meetings South East Region The Inaugural Meeting of the Region was held at 6.30 p.m. on Wednesday, May 21st, 1975, a t the Linnean Society, Burlington House, Picca- dilly, London, W.l. The meeting was opened by the President of the Analytical Division, Dr. G. W. C. Milner, who introduced the Chair- man of the Region, Mr. C. A.Johnson. Mr. Johnson then took the Chair. Mr. C . A . Johnson (L) taking over the Chair from the President. A lecture on “The Chemical Industry and Analytical Chemistry-Three Ages” was given by C. Whalley. Mr. Johnson announced the members of the ad hoc Committee of the Region as follows. Chairman-Mr. C. A. Johnson. Honorary Secretary-Dr. J. Warren, Laboratory of the Government Chemist, Cornwall House; Stam- ford Street, London, SE1 9NQ.Honorary Treasurer-Mr. D. W. HoughtOn. Members of Committee-Dr. A. H. Andrews, Mr. R. Goulden, Dr. S. J. Lyle, Mr. R. Sawyer and Mr. W. H. C. Shaw. The lecture was followed by a cheese and wine party in the Rooms of the Chemical Society, Burlington House. Midlands Region An Ordinary Meeting of the Region was held at 6 p.m.on Tuesday, May 13th, 1975, at Henry Wiggin and Co. Ltd., Hereford, when a disputa- tion in the form of an ecclesiastical court took place. The Vice-chairman of the Region, Dr. A. Townshend, explained the rules of the meet- ing and introduced the “Cardinals,” Professor R. Belcher, Professor E. Bishop, Dr. A. A. Smales, Dr. D. Thorburn Burns and Mr. C. Whalley, and the “Devil’s Advocate,” Dr.L. S. Bark. In the unavoidable absence of the President, who was to have acted as “Pope,” it was announced that the Cardinals had held a hurried election and had elected Mr. Whalley to act in this capacity. Five analytical techniques were put forward as the techniques most free from the cardinal errors of imprecision, insensitivity, restricted range, low cost effectiveness, labour intensive- ness and limited applicability.Each postulator in turn was allowed ten minutes to put his case, and was then subjected for five minutes to detailed cross-examination and to the good- natured but, at times, sharp wit of Dr. Bark. The postulators were Mr. S. Greenfield (plasma spectroscopy), Mr. P. W. Hurley (X-ray fluorescence), Mr. J. Woodward (atomic spectro- scopy), Dr.V: J. Jennings (polarography) and Dr. D. J. Williams (colorimetry). After the postulators had presented their cases and been cross-examined by Dr. Bark, the Cardinals discussed the techniques generally and then each in turn advised the Pope as to the merits of each case as presented. Mr. Whalley thanked the Cardinals for their advice and, after summing up, announced that he had decided that two of the techniques were worthy of canonisation on the cases presented, namely plasma spectroscopy and polarography .Joint 1\11 eet i ng A Joint Meeting of the Scottish and North East Regions with the Microchemical Methods, Atomic Spectroscopy, Chromatography and Electrophoresis, Automatic Methods, Radio- chemical Methods and Electroanalytical Groups was held on Thursday and Friday, June 19th and ZOth, 1975, in the Department of Chemistry, The University, St.Andrews. The subject of the meeting was “The Application of New Techniques in Environmental Analysis.” Members were welcomed by Dr. J. M. Ottaway, Chairman of the Scottish Region, and by Professor P. A. H. Wyatt on behalf of the University of St. Andrews. The Chair at the first session was taken by the President of the AD, Dr.G. W. C. Milner. The following papersJuly, 1975 FOURTH THEOPHILUS REDWOOD LECTURE 199 were presented : Plenary Lecture on “Rational Priorities for Pollution Control,” by Professor D. Bryce-Smith ; “The Continuous Monitoring of Effluents Using Ion-selective Electrodes,” by M. E. Hofton; “Determination of Steroids in Effluents,” by J.P. Dawson and G. Best. The Chair at the second session was taken by Mr. A. E. Bottom, Chairman of the Electroanalytical Group, and the following papers were presented and discussed : “Variability in the Chemical Composition of Sea Water,” by E. J. Hamilton; “The Application of Radionuclide Measurements to the Study of the Marine Environment,” by J. W. R. Dutton; “Spark-source Mass Spectro- metry of Soils,” by A.M. Ure; “Problems Associated with the Mass Spectrometric Con- firmation of Nitrosamines in Foodstuffs,” by K. S. Webb; “Studies of Lead in Exhaust Particulates by Radioactive Tracer Tech- niques,” by A. Morgan. The Chair at the third session was taken by Dr. R. Smith, Chairman of the Atomic Spectro- scopy Group, and the following papers were presented and discussed : “Legislation with Regard to Present and Future Requirements,” by E.A. B. Birse; “The Automated Analysis of Fresh Water Systems as a Means of Pollution Control,” by C. S. Franklin; “Polarographic Studies of Some Organic Pollutants in Water,” by W. F. Smyth, J. P. Hart and M. Hassanzadeh; “Biological Activity Measurement and its Application to Pollution Control,” by P.Coackley. The Chair at the fourth session was taken by Mr. F. E. Harper, Chairman of the North East Region, and the following papers were presented and discussed : “Recent Develop- ment in the Analysis of Carbon Monoxide in Air and Blood,” by B. T. Commins; “Multiple Pollutant Monitoring using Spectroscopic and Gas Chromatographic Methods in a Mobile Laboratory,” by P.A. Hollingdale-Smith ; “Carbon Furnace Atomic-absorption Analysis of Atmospheric Particulates,” by J. M. Ottaway and D. C. Hough; “Instruments for the Con- tinuous Analysis of Air Pollution in an Urban Environment,” by H. M. N. Stewart. The Conference Dinner was held on the even- ing of Thursday, June 19th, a t which the President presented the Robert Boyle Essay Award to Ian C. Hunter of Rubislaw Academy, Aberdeen, and a short address was given by Professor H. M. N. H. Irving. The meeting also included a full social programme. Electroanalytical Group A meeting of the Group was held a t 3 p.m. on Friday, June 13th, 1975, in Lecture Theatre C, Chemistry Department, Imperial College, Lon- don, S.W.7. The Chair was taken by the Chairman of the Group, Mr. A. E. Bottom. A lecture on “Micromolar Analysis-Sinu- soidal Hydrodynamic Modulation at the Rotat- ing Ring-disc Electrode” was given by S. Bruckenstein.

ISSN:0306-1396    

DOI:10.1039/AD9751200198

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

July, 1975 FOURTH THEOPHILUS REDWOOD LECTURE 199 The Fourth Theophilus Redwood Lecture* Polarography in Attacking Practical and Theoretical Problems in Analytical Chemistry Petr Zuman Department of Chemistry, Clarksan College of Technology, Potsdam, N . Y . 13676, USA When I was told that the honour of delivering the Fourth Theophilus Redwood Lecture had been bestowed upon me, I felt that the link between the USA and the UK, which had become my second homes, should be reflected in my lecture.In this paper, I have concentrated on two aspects that link my personal experiences in these two countries, namely the use of polarography in trace analysis and the study of course and mechanisms of chemical reactions. Before considering these two topics, it is useful to recall briefly the development of polaro- graphy, which formed the basis and permitted the advancement of such applications.In this connection, I can rely on my links with my original home, Prague, and my esteemed teacher, Professor J. Heyrovskg (Fig. 1). In 1922, he introduced the dropping-mercury electrodel into electrochemistry and showed that current - voltage curves obtained with such electrodes are analytically important.Professor J. Heyrovskg recognised a t an early stage that polarographic limiting currents or wave heights are a linear function of concentration and with his collaborator, D. IlkoviE, he proposed a theoretical treatment2-4 that substantiated such relationships. * Presented at the CS Annual Chemical Congress held at The University of York, April 7-11th.1975.200 FOURTH THEOPHILUS REDWOOD LECTURE Proc. Analyt. Div. Chem. SOC. During the 1940s and 1950s, polarography was applied success- fully to numerous analytical problems in both inorganic and organic analysis. Polarographic methods of analysis found uses first of all in metallurgy, then in the just developing nuclear chemistry, in food analysis, clinical chemistry, the analysis of agricultural pro- ducts and pharmaceutical analysis, and also in procedures used in the control of the manufacture of fine and heavy chemicals, toxicology, industrial hygiene and what we now call environ- mental analysis.Because of its speed, selectivity and, in some instances, sensitivity, polarography was often as satisfactory as, or an even more suitable analytical tool than, titrimetric, colorimetric and spectrophotometric procedures.Instances when polaro- graphic analysis was so superior to other techniques that its use in practical problems compensated for the need for more skilled personnel grew in number. A reversal of this trend happened with the advent of atomic- absorption spectrophotometry. In the 1960s, when this tech- nique was introduced, it offered simple manipulation, selectivity (which nevertheless turned out to be less general than had- originally been assumed) and an important increase in sensitivity, which for some metal analyses was one or two orders of magnitude higher than that offered by classical d.c.polarography. Why, at a time when the ad- vances made in electronics after World War I1 were being widely applied, was it not possible simply to develop techniques for the measurement of smaller currents, which would lead to an increase in sensitivity? The principal reason had already been recognised in the 1930s, based on theoretical treatments by IlkoviE5 and HeyrovskJi,6 namely the condenser or charging current.Every electrode immersed into a solution must form a double layer on its surface and only then can faradaic processes take place.A certain amount of electrical current is consumed in order to charge each successive drop corresponding to the applied voltage. It is characteristic of this current that it depends on the potential, the nature of the supporting electrolyte and the geometry of the electrode, but not on the concentration of the species to be determined.This current also depends in a characteristic way on time: it is greatest immediately after the volt- age has been applied and decays rapidly. In classical d.c. polarography, mean currents during the life of each drop have been recorded and measured. When measurements were carried out in solutions containing a 10-4 M con- centration of electroactive species, the mean capacity current was small when compared with Professor P.Zuman. How did electroanalytical chemistry face this challenge? Fig. 1. Professor J. Heyrovskf with Professor D. IlkoviC.July, 1975 FOURTH THEOPHILUS REDWOOD LECTURE 201 the mean faradaic ( i e . , electrolytic) current and could be neglected (Fig. 2 ) . In solutions con- taining a M concentration of the species to be determined, capacity currents were often comparable with faradaic currents and corrections for capacity currents had to be introduced in the measurement of electrolytic currents.M level, the capacity current became larger than the faradaic component of the recorded current (Fig. 2) and the exact measurement of the electrolytic current and hence the determination of concentration became difficult.Finally, at the - - t t Fig. 2. Changes of instantaneous current with time during the life of a single drop: ZF, faradaic current; ZC, charging current. (a) 5 x 10-4 M ; ( b ) , 5 x M ; and ( c ) , 5 x M (schematic; different current scales). It was at this stage that British inventiveness became a decisive factor. Rather crude and only partly successful attempts to eliminate or compensate for the charging current had been made before, but it was only through the ideas of Geoffrey Barker7y8 a t Harwell that progress was made.He discovered that, in order to diminish the role of the capacity current, it was necessary to reject the measurement of mean currents and instead to carry out repetitively the current measurement after a certain interval following the application of alternating voltage steps to a given drop.After such an interval, the capacity current decayed and the measured current corresponded predominantly to the faradaic current. Moreover, the interval during which the measurement was carried out was chosen in such a period of the life of each drop that the growth of the drop was slow and the surface of theelectrode was virtuallyconstant (Fig.3). In order to achieve such conditions of measurement, it was necessary to apply the voltage step- wise. A square-wave voltage was applied to a freshly grown mercury drop in addition to the almost constant voltage, which is effectively applied to each drop in the slow scanning of voltage, as used in classical polarography.or lo-' M concentrations in solutions. However, the instrumentation was complex, expensive and there was often the possibility that one of the 90 or more electron tubes would behave imperfectly. Barker therefore developed a slightly simpler instrument, working on similar principles, with comparable sensitivity, uiz., the pulse p~larograph.~,s Commercial instruments that enabled pulse polarographic curves to be recorded were developed in the UK.These instruments were built for a single purpose and were rather expensive. Recent developments in instru- mental methods clearly indicated that a basic condition for the general adoption of an instru- mental technique is that simple, cheap and reliable instruments must be commercially avail- able.Apart from the well known example of spectrophotometry, even the growth in the use of d.c. polarography was basedon the early availability of Czech photorecording and Danish pen- recording polarographs. Later, reliable pen-recording polarographs originated from the USA, France and Italy. Cambridge Instruments in the UK produced two instruments, which at that time were among the best instruments available in the world.Unfortunately, because of sales policies, these instruments never became as widely accepted as they deserved. At a time when European firms developed new concepts, Princeton Applied Research manu- factured the first expensive multipurpose instruments, and shortly afterwards introduced the 174 Polarographic Analy~er.~ This simple, inexpensive, reliable instrument permits both d.c.and pulse polarographic curves to be recorded, the latter in two modes, integral and differential. The shape of the curves obtained with integral pulse polarography resembles that of the waves obtained in d.c. polarography. In this method, voltage pulses of gradually increasing A square-wave polarographs was developed and the sensitivity increased to At this stage, the link with the USA became important.202 FOURTH THEOPHILUS REDWOOD LECTURE Proc.AnaZyt. Div. Chem. SOC. amplitude are applied to the electrodes (Fig. 4) and the current is measured only during the second half of the pulse. The sensitivity is increased owing to the elimination of the greatest part of the charging current, but two limitations of d.c.polarography remain: interference from excess of species reduced at more positive potentials and interference due to the small difference in half-wave potentials. 1 1 I I I I i i 7 7 7 7 Y - e v - e Fig. 3. Use of rectangular voltage polarisation. (a), Change of applied voltage with time; (b), change of faradaic current with time; and (c) change of charging current with time. T = period of current measurement.Time 7 t - 2s Time - r t 2s Fig. 4. Change of applied voltage with time for pulse polarography. ( a ) , Integral pulse polarography, gradually increased amplitude; and (b), differential pulse polarography, constant amplitude (50mV) superimposed on a voltage ramp. t = Drop time, delay 2 s, T = pulse duration (schematic ; not to scale). The importance of these two limitations is diminished in differential pulse polarography, where constant-amplitude voltage pulses are superimposed over a linearly increasing voltage ramp.The difference in the current just before the application of the pulse and towards the end of the pulse is measured (Fig. 5) and plotted against potential. The curves obtained in differential pulse polarography are peak-shaped, unaffected by processes that take place at more positive potentials and permit better resolution of adjacent waves.The sensitivity is comparable with that of square-wave polarography for reversible systems, and better than that for irreversible systems. Ex- amples of direct.applications are the determination of lead in blood and the analysis of anti- biotics [ e g ., chloramphenicol (Fig. 6) or tetracycline]. Such determinations can frequently be carried out at the M (or about 1 p.p.m.) concentration level, and sometimes at concentra- tions one order of magnitude lower. We have used differential pulse polarography for the determination of trace amounts of phenobarbital in blood.1° The polarographic determination of barbituric acid derivatives is based on the measurement of anodic waves, corresponding to the formation of slightly soluble compounds with mercury.These anodic waves are a linear function of concentration only up Differential pulse polarography proved to be an excellent method for trace analysis.J d v , 1975 FOURTH THEOPHILUS REDWOOD LECTURE 203 Time --w I # 1 1 I 0.0 -0.2 -0.4 -0.6 -0.8 Potential (E vs.S.C.E.) Fig. 6. Differential pulse polaro- graphic curves of chloramphenicol in acetate buffer of DH 4-0. Con- - . . - - -. Fig. 5. Change of applied voltage with time and mode of current measurement in differential pulse polarography. Current sampled during 16.7 ms before the pulse rise and a t the end of the pulse; difference in these two currents measured. centrations indicatedLon curves.to a certain concentration, which, in d.c. polarography, is of the order of M. The wave is well developed for barbital, but ill-defined for phenobarbital. Whereas the use of short drop- times or a streaming electrode increases the concentration range to higher concentrations, the waves for phenobarbital remain difficult to measure when d.c. polarography is used.Peaks obtained in solutions of phenobarbital in borate buffers can be readily measured (Fig. 7) and their total heights are a linear function of concentration over a wide range. Differential pulse polarography was used successfully for the determination of phenobarbital in blood serum (Fig. 8), even in the presence of N-alkyl- and NN'-dialkyl-substituted barbiturates and other drugs used in the treatment of epilepsy.P Fig. 7. Differential pulse polarographic curves of phenobarbital in borate buffer of pH 9.3. Phenobarbital concentration: A, 0.5; B, 1.0; C, 1.5; and D, 2.0 x M. For amalgam-forming metals, a further increase in sensitivity by two to three orders of magnitude is possible, when the metal ion is pre-concentrated by the electrolytic formation of an amalgam, from which the metal is then dissolved by a gradually changed voltage and the anodic curve of amalgam dissolution is measured (the so-called anodic stripping).The advantage of using pulse polarographyll in connection with a hanging mercury drop electrode or a solid electrode plated with mercury lies in the higher sensitivity of the pulse204 FOURTH THEOPHILUS REDWOOD LECTURE Proc.AnaZyt. Div. Chem. Soc. Fig. 8. Blood serum extracted with ether and dried extract dissolved in borate buffer of pH 9.3. Differential pulse polarographic curves : A-E, for five patients after administration of bar- biturates. Phenobarbital in blood serum. method. The concentration of the metal in the amalgam necessary to give measurable signals is smaller and hence-the time needed for electro-deposition during the pre-concentration period is shorter in the pulse method.Frequently, pre-electrolysis for 1-5 min is sufficient, whereas in d.c. anodic stripping 30-60 min are often necessary. Apart from savings in time it is also easier to control the conditions (mainly convection) during the shorter time period. This approach has been used successfully for the determination of trace amounts of heavy metals in water, in particular in drinking water (Fig.9) and natural waters, including sea water. In order to eliminate the effects of trace amounts of organic materials ac.ting as surfactants, treatment with infrared lamps proved successful. Zinc, p.p.b. 1800 1 13-7 I I I I I I -1.2 -1.0 - 0 8 -06 -0.4 - 0 2 O Potential ( E vs.S.C.E.) Fig. 9. Analysis of drinking water from Washington, D.C., pre-electrolysed for 1.25 min, using a hanging mercury drop electrode; differ- ential pulse anodic stripping curve recorded. Insert : Pre-electrolysis for 5.25 min for deter- mination of lead. Trace amounts of heavy metals can also be determined in de-ionised water used in the manu- facture of printed circuits.12 Organic materials eluted from ion exchangers did not interfere.In order not to introduce impurities, we saturated the solution being analysed with carbon dioxide and/or ammonia so as to provide a supporting electrolyte. Concentrations at the 0.001 p.p.m. level gave reproducible results. Attention had to be paid to contamination by containers, particularly those made from polyethylene and PTFE.July, 1975 FOURTH THEOPHILUS REDWOOD LECTURE 205 We have recently applied differential pulse polarography to the solution of another, princip- ally analytical, pr0b1em.l~ In the study of electro-oxidation of benzaldehydes, the change in d.c.anodic waves with hydroxide-ion concentration did not make it possible to decide whether the disappearance of the wave is due to a gradual decrease in the anodic wave or to a gradual shift of the wave to more positive potentials.Differential pulse polarographic curves clearly indicated that a decrease in the wave height is involved. This observation was of major im- portance in understanding the electro-oxidation process and for finding the optimum conditions for the determination of these aldehydes.Returning to purely analytical aspects, a comparison of pulse polarography with other electrochemical methods (Table I) and with other methods of trace analysis (Table 11) indicates the usefulness of the technique. It is thus possible to conclude, leaving aside economic con- siderations, that the creative work of a British scientist and the timely production of an appro- priate instrument by an American manufacturer contributed to the progress of analytical chemistry and brought polarography back into the mainstream of analytical methods, particu- larly for trace analysis.The theoretical understanding of pulse polarographic curves for more complex electrochemical processes is, nevertheless, as yet limited and offers wide research opportunities.TABLE I COMPARISON OF SOME ELECTROANALYTICAL TECHNIQUES No. of papers Technique published Separation/V Concentration limit/M Polarograph y >40 000 >om1 5 x 10-6 voltammetry (D.M.E.) -1000 > 0-05 1 x 10-7 Pulse polarography -100 > 0-05 1 x 10-8 (d.c. + pulse) -1000 >o-1 1 x 10-9 Linear sweep Stripping voltammetry TABLE I1 DETECTION LIMITS (p.p.m.) OF SOME TRACE ANALYTICAL METHODS Method r 7 -A Polarograph y Element Colorimetry Neutron -7 activation D.C.Pulse c u 0.03 0.000 35 0.2 0.001 Pb 0.03 0.1 0.5 0.001 Cd 0.0 1 0.0035 0.1 0.00 1 In 0.2 O*OOO 005 0.1 0.00 1 analysis Turning to the second topic, reaction mechanisms, my involvement in Anglo-American collaboration is more personal. During my stay at the University of Birmingham, I supervised the work of David Barnes, who investigated the polarographic reduction of cinnamaldehyde.14-ls As the product of the two-electron reduction was 3-phenylpropionaldehyde, it was necessary to compare the behaviour of the reduction product with that of the authentic aliphatic aldehyde.It has been recognised that our understanding of the reduction of aliphatic aldehydes (other than formaldehyde) was limited and the use of polarography as a method for understanding hydration - dehydration equilibria was not fully appreciated.17 This work in Britain laid the foundation for our present investigations in the USA.Bell18 at Stirling proposed the following mechanism for the hydration - dehydration reaction : k, 0- .. - . (1) >C=O+B+H,O >C/ +BH+ .. .. .. k-1 \OH OH -- - * (2) >C/O-+ BH+ ---- >c<OH + B ' .... .. .. .. \OH fast206 FOURTH THEOPHILUS REDWOOD LECTURE Proc. Analyt. Div. Chem. SOC. where the source of the second oxygen atom in the hydrated form was water and the increase in the rate of hydration was base catalysed. Based on polarographic evidence17 that the rate of dehydration first increases with increasing pH but then decreases, that some aldehydes (e.g., benzaldehydes) only add hydroxide ionslS and that in the middle pH range a competitive reaction with water predominates,2o the following reaction was proposed21 : k3 0- >C=O+OH- >c/ .... .. . . .. . . k-3 \OH fast OH \OH K , \OH >C /O- + H20 >C/ + OH- .. .. .. .. >C=O+H,O >C/OH2+ .. .. .. .. .. k5 k- 5 \O- followed by reaction (4).At a pH of about 7, equilibria (6) and (4) are shifted to the right- hand side and the rate of the reaction with water appears to be independent of pH. A shift of equilibrium (4) to the left-hand side is responsible for the increase in the rate of dehydration with rate constant k-3. An increase in the rate of the hydroxide addition reaction with rate constant k, in strongly alkaline media explains the observed decrease in dehydration rate at pH above 13. The rate constants for hydroxide addition are higher than those for water addition, which is in agreement with the greater nucleophilicity of hydroxide than of water.The scheme depicted by reactions (3)-(6) seems to be in agreement with all available experi- mental evidence.l7y2l The effect of bases other than hydroxide or water is attributed to their nucleophilic reactivity rather than general base catalysis.Qualitatively, reactions (3)-(6) are in agreement with rather complex behaviour, such as that of W, W , w-trifluoroacetophenone,22 studied in Potsdam by a British Post-doctoral Fellow, W. J. Scott from Belfast. The correctness of this scheme has been supported by the behaviour of substituted benza1dehydes,l3y19 for which reaction (3) predominates.Further, a similar reaction with alk- oxides and alcohols has recently been reported.23 Nevertheless, the complete quantitative evaluation of reactions (3)-(6) has not yet been achieved. This scheme involves four rate constants (k,, k3, k5 and kb5) and, in order to find their numerical values, four measurable parameters would be needed.For most carbonyl compounds studied, the value of the over-all ratio [C=O]/[C(OH),] can be determined and the rate of concentration change of the free carbonyl form followed. In some instances, the value of the acid - base dissociation constant, K,, is accessible. It seems to be possible to develop experimental methods that would allow a rigorous treat- ment of the above system, but they are rather demanding.An attempt is being made instead to find a system where the dehydration reaction with rate constant k-, would be slow. This would enable us to treat equilibrium (5) as being slowly established, which in turn would permit the determination of rate constants k , and k-,. The choice of the model system was based on the assumption that the stronger the hydration, the slower is the dehydration.Attention has thus turned to the polarography of halogenated aldehydes24 and ketones.25 It has been shown that for all compounds studied the non- hydrated form, and for polyhalogenated species also the hydrated form, undergoes reductive cleavage of the C-X bond, as shown in scheme (7).In scheme (7) the hydration - dehydration equilibria with constants Kk,o and K:*o are shown only schematically. Even for the most strongly hydrated of the compounds studied, viz., chloralM and hexachlor~acetone,~~ the rate of dehydration corresponding to the reaction with rate constant kL5 is still too fast to enable reaction (3) to be studied.July, 1975 OH2+ cx,c/ ' I \OH CX,C=OH+ I R I CX,C+-OH 1 *8 1-6 1 -2 0 FOURTH THEOPHILUS REDWOOD LECTURE OH CX,COOH (R = H) Kh KB 0- +x+ I R R -2 Kc cx,c=o -2 TK+ I R cx,-,c =o I R +x- 207 .... * - (7) .. .. 200 225 200 225 250 Xlnm Fig. 10. Ultraviolet spectra. (a), Varied concentra- tion of sodium hydroxide in water, range 1-0 x 10-4- 14.0 x M. (b), pH dependence of chloral hydrate in various buffers at 25.0 "C.[Cl,CCH(OH),] = 5.0 x 1 0 - 4 ~ . pH values: A, 1.3; B, 7-9; C, 9-1; D, 9.5; and E, 10.4.205 FOURTH THEOPHILUS REDWOOD LECTURE Proc. Analyt. Div. Chem. SOC. Why is such a study of the mechanism of reaction (7) of importance in chemical analysis? Firstly, an understanding of the mechanism permits a choice of the optimum conditions for a given analytical problem. Hence, the determination of chloral and its hemiacetal in the pres- ence of other chloroaldehydes and chloroacetones (with the exception of the hexachloroacetone) is possible by measuring the wave at -1.3 V at pH 7-9.For the determination of mono- chloroacetone, measurement of the wave height at -1.OV in0.1 M sulphuric acid is the most suitable procedure. Secondly, the study revealed the existence of some less frequently encountered species.Whereas the existence of the carbonium ion in acidic media, confirmed by spectroscopic measurernent~,~~ is mainly of theoretical interest, the proof of the existence of the anion of the geminal diol CX,CR(OH)O- proved to be of practical importance. Not only does this species undergo oxidation (for R = H, derived from aldehydes), but its absorbance in the ultraviolet region (Fig.10) led to the in~estigation~~ of the ultraviolet absorption of other anions, such as OH-, OR-, SH-, RS-, SeH- and TeH-. For example, the absorbance of OH- at 205 nm is a linear function of concentration and is independent of whether lithium, sodium or tetramethyl- ammonium hydroxide is used, and hence suitable for analytical application.Similar results were obtained for the ultraviolet absorption spectra of the other anions mentioned, which can be used for the determination of the anions at the 10-4-10-3 M level. Moreover, the absorbance can be used for the determination of pK values, e.g., of hydrogen sulphide. These examples perhaps indicate how a study of fundamental problems by means of polaro- graphy in connection with other methods can contribute to solving problems of analytical importance.I realise that without the contribution of my esteemed teacher, J. Heyrovskjr, I would not have been able to try to promote such studies on both sides of the Atlantic. I would also not have had the opportunity of delivering this lecture, for which I am profoundly grateful to the Society.1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. References Heyrovskq, J., Phil. Mag., 1923, 45, 303. IlkoviE, D., Colln Czech. Chem. Commun., 1934, 6, 498. IlkoviE, D , J . Chim. Phys., 1938, 35, 129. Heyrovskf, J., and IlkoviE, D., Colln Czech. Chem. Commun., 1935, 7, 198. IlkoviC, D., Colln Czech. Chem. Commun., 1936, 8, 170. Heyrovskq, J., “Polarographie,” Springer Verlag, Vienna, 1941. Barker, G. C., and Gardner, A. W., 2. Analyt. Chem., 1960, 173, 79. Barker, G. C., in Zuman, P., and Kolthoff, I. M., Editors, “Progress in Polarography,” Volume 2, Interscience, New York, 1962, p. 411. Flato, J. B., Analyt. Chem., 1972, 44, 75A. Romer, M., and Zuman, P., unpublished results. Siegerman, H., and O’Dom, G., Am. Lab., June, 1972. Delaney, M., Frankel, H., and Zuman, P., unpublished results. Bover, W. J., and Zuman, P., J . Electrochem. Soc., 1975, 122, 368. Barnes, D., and Zuman, P., J . Electroanalyt. Chem., 1968, 16, 575. Barnes, D., and Zuman, P., Analyst, 1968, 93, 589. Barnes, D., and Zuman, P., Trans. Faraday Soc., 1969, 65, 1668 and 1681. Barnes, D. and Zuman, P., J . Electroanalyt. Chem., 1973, 46, 323 and 343. Bell, R. P., in Gold, V., Editor, “Advances in Physical Organic Chemistry,” Volume 4, Academic Press, Bover, W. J., and Zuman, P., J . Chem. Soc., Perkin Trans. I I , 1973, 786. Zuman, P., Barnes, D., and Ryvolovk-Kejharovk, A., Discuss. Faraday Soc., 1968, 45, 202. Zuman, P., Barnes, D., Bover, W. J., and Scott, W. J., Tetrahedron, in the press. Scott, W. J., and Zuman, P., Electrochim. Acta, in the press. Crampton, M. R., J . Chem. SOG., Perkin Trans. 11, in the press. Szafranski, W., and Zuman, P., unpublished results. Romer, M., and Zuman, P., unpublished results. New York, 1966, p.1.

ISSN:0306-1396    

DOI:10.1039/AD9751200199

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

July, 1975 ELWELL AWARD MEETING 209 Elwell Award Meeting The following is a summary of one of the papers read at the Elwell Award Presentation Meeting of the Midlands Region held on January 14th, 1975, and reported in the March issue of Proceedings (p. 75). The Behaviour of Some Sulphur Anions in the MECA Cavity D. J. Knowles Department of Applied Chemistry, Preston Institute of Technology, Plenty Road, Bundoora, Victoria, Australia 3083* Some of the most sensitive emissions observed in molecular emission cavity analysis (MECA)l are derived from sulphur-containing species., This enables the technique to be used for qualitative and quantitative analysis of the inorganic sulphur anions by measurement of S, emission derived from these species.A study of aqueous solutions of sulphate, sulphite, peroxy- disulphate, metabisulphite, thiosulphate, thiocyanate and sulphide has shown that each of these anions is amenable to MECA analysis and thus it provides a rapid means of analysis for these species.Experimental The instrument used for these investigations is a prototype MECA spectrophotometer (Anacon Inc., Ashland, Mass., U.S.A.). A pre-mixed nitrogen - hydrogen ( - air) flame is established above a burner, which can be adjusted in both the horizontal and vertical positions.The cavity in which the emission is produced is placed into the flame by rotation of the block assembly that holds it. The cavities used were made of silica. The emission established in the cavity passes via an 8-nm slit and a monochromator to a photomultiplier, the output of which is fed to an Oxford 3000 recorder.This recorder has a particularly fast response (0.2 s, 90 per cent. full-scale deflection), which is essential for the study of those anions with fast response times in the flame. Results and Discussion Sulphate Ion Aqueous sulphate solutions vary in their MECA behaviour, depending on the cation present. Sulphuric acid gives a good response, whereas sodium sulphate has a very poor response, which is rapidly diminished on successive measurements in the same cavity.This depressive effect of metal cations can be overcome by addition of orthophosphoric acid to the solution. It is found that sulphate solutions of H+, Na+, NH,+, Fez+ and Mn2+, which are made 0.1 M with respect to orthophosphoric acid, all give responses at the same time after insertion intothe flame, and the emission intensity per nanogram of sulphur is also the same.Hence it is possible to determine the sulphate concentration in aqueous solution by addition of orthophosphoric acid and measurement against a set of standard solutions. It is suggested that the orthophosphate replaces the sulphate ion and liberates it as sulphuric acid.Some of these effects are shown in Fig. 1. Peroxydisulphate gives a response in the presence of orthophosphoric acid. This occurs at the same time as the sulphate response and with the same emission intensity per sulphur atom as sulphate. Sulphide, Thiocyanate, Thiosulphate, Metabisulphite and Sulphide Ions Salts of each of these anions give a much higher emission than the sulphates from aqueous solution.Nevertheless , the addition of phosphoric acid enhances considerably the emission observed and also removes the interference of metal cations present. Two of the anions, vix. thiosulphate and sulphide, were studied with 1 + 1 ammonium dihydrogen orthophosphate - diarnmonium hydrogen orthophosphate buffer addition instead *This work was performed while the author was working in the .Chemistry Department, University of Birmingham.210 CONFERENCES AND MEETINGS Proc.Analyt. Div. Chem. SOC. I I I I I I I I I I I I , , 0 20 0 20 0 20 40 60 80 0 20 Timels Fig. 1. MECA responses from: (a) an aqueous solution of KSCN, A, alone and, B, with phosphoric acid; and (b) an aqueous solution of MnSO,, A, alone and, B, with phosphoric acid.of orthophosphoric acid. pectively, renders the solutions unsuitable for MECA. phate buffer enables good quantitative measurements to be made. In the former medium, disproportionation or volatilisation, res- In both instances, the use of the phos- tm Values Any particular species is characterised by the time taken to reach maximum emission intensity (tm) after introduction of the cavity into the flame.This time is dependent on the gas flow-rates used and the size of the cavity, but for a given set of conditions remains the same for any measurement on a particular anion. S,032-, SCN- and S2052-; and SO,2- and S20,2-, whose tm values are 8 s. This behaviour pointed to the possibility that a mixture of sulphate ions with one of the anions with a faster response time, such as sulphite, might yield two emissions associated with the two anions.Preliminary studies indicated that this phenomenon is observed and thus the simultaneous determination of two or more of the sulphur anions in admixture is possible. The author acknowledges the generous leave provisions afforded him by the Council of the Preston Institute of Technology. He thanks Professor R. Belcher for the hospitality extended to him in his laboratories and Dr. S. L. Bogdanski and Dr. A. Townshend for many enlightening discussions. Broadly, the anions fall into two groups: those with tm values <4 s, viz. S2-, References 1. Belcher, R., Bogdanski, S., Ghonaim, S. A., and Townshend, A., Analyt. Lett.. 1974, 7, 133. 2. Belcher, R., Bogdanski, S. L., and Townshend, A., Analytica ChZm. Acta, 1973, 67, 1.

ISSN:0306-1396    

DOI:10.1039/AD9751200209

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

210 CONFERENCES AND MEETINGS Proc. Analyt. Div. Chew. SOC. Conferences and Meetings Course on Solid - Liquid Separation The course will cover the physical and engin- September 8-11, 1975, Bradford eering aspects of separation of particulate Following the outstanding success of the 1974 matter from liquids. While not exclusively course, the Institution of Chemical Engineers is concerned with filtration and separation, these sponsoring a further and extended course on operations will be dealt with in depth.The Solid - Liquid Separation to be held at the Uni- treatment will be such that prior knowledge of versity of Bradford from September 8th to 11th. the subject is not essential. Emphasis will beJuly, 1975 CONFERENCES AND MEETINGS 211 laid on those aspects of this f a s t expanding technology which are of immediate practical importance.The course will be particularly useful to industrialists seeking a concise cover- age of the essential principles and recent developments of importance in the subject. Further particulars may be obtained from Dr. L. Svarovsky, Schools of Chemical Engineer- ing, University of Bradford, Bradford, Yorkshire, BD7 1DP. Course on Industrial Effluent Pollution September 14-19, 1975, Loughborough The course will consider sources and types of aquatic pollution, effects on health and the environment, operation of sewage works, methods of pollution measurement (emphasising recent advances in measurement and monitoring and including legal aspects) and treatment of effluents.A visit to a sewage works is included and there will be a case study presentation of effluent treatment and disposal at the Boots Company, Nottingham.For further information, contact the Centre for Extension Studies, Loughborough Univer- sity of Technology, Loughborough, Leicester- shire, LEll 3TU. Conference on Instruments and Control Systems September 15-17, 1975, University of Reading This Conference will report current trends and achievements in the use of instrumentation and control systems to monitor quality and quantity of natural waters and water supply.Numerous case studies will illustrate the operational aspects of the various topics and an informal workshop will feature an exhibition of equipment. The principal topics to be covered by invited papers are: monitoring quality and quantity of surface and groundwaters, instrumentation and automation in resource management, water treatment and distribution, and instrumentation and control in waste water treatment.There will also be an exhibition of equipment. For further information, contact Mr. C. F. Cooper, Water Research Centre, Medmenham Laboratory, P.O. Box 16, Ferry Lane, Medmen- ham, Marlow, Bucks., SL7 2HD.AOAC Annual Meeting October 13-16, 1975, Washington, D.C. The Association of Official Analytical Chemists will hold its 89th Annual Meeting on October 13-16th at the Marriott Hotel, Twin Bridges, Washington, D.C. The latest developments in analytical methodology for many commodities and materials important to agricultural and public health areas will be presented and dis- cussed.About 240 papers will be given on new techniques, methods and instrumentation for analysis of drugs, feeds, fertilisers, foods, food additives, pesticides, flavours,: beverages, micro- biological contamination of foods, mycotoxins and related subjects. The Society of Cosmetic Chemists and the AOAC will hold a joint Symposium on Cosmetic Analytical Techniques on October 13th.Addi- tionally, evening workshops are being planned on automated analyses and thin-layer chroma- tography, and about 40 firms will exhibit the latest laboratory equipment and supplies. For further details, contact Luther G. Ensminger, AOAC, Box 540, Benjamin Franklin Station, Washington, D.C. 20044, USA. 1 lth International Symposium on Chroma- tography July 5-9, 1976, Birmingham This Symposium, to be held under the auspices of the Chromatography Discussion Group, the AD Chromatography and Electrophoresis Group, the Groupement pour 1’Avancement des Methodes Spectroscopiques et Physicochimiques d’Analyse (GAMS) , the Arbeitskreis Chromata- graphie and the Groupo de Cromatografia, will cover all aspects of chromatography and associated techniques, with emphasis on gas and high-performance liquid chromatography. An exhibition of equipment will also be held.Those who wish to submit papers should send a 300-600-word abstract by October 31st to: E. R. Adlard, Thornton Research Centre, P.O. Box 1, Chester, CH1 3SH. Further information can be obtained from The Executive Secretary, Chromatography Discussion Group, Trent Polytechnic, Burton Street, Nottingham, NG1 4BU.3rd International Symposium on Analytical Pyrolysis September 7-9, 1976, Amsterdam Papers will be presented on the principles and applications of pyrolysis in combination with chromatographic, spectrometric and computer techniques in the fields of polymer science, biochemistry, forensic science, pharmacology, microbiology and medicine. Special attention will be paid to new techniques, specificity, reprc- ducibility, automation and data processing. An exhibition of equipment will also be held. Further information can be obtained from Miss Ria Priester, FOM-Institute for Atomic and Molecular Physics, Kruislaan 407 , Amster- dam 1006, The Netherlands.

ISSN:0306-1396    

DOI:10.1039/AD9751200210

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

212 SILVER MEDAL Proc. Analyt. Div. Chem. SOC. Publications Received The Determination of Vinyl Chloride. A Plant Manual. Edited by W. Thain. Pp. viii + 92. London: Chemical Industries Association Limited. 1974. Price L20. Practical Electrophoresis. G. J. Moody and J. D. R. Thomas. Technical Library, MTL/PS/S. Watford: Merrow Publishing Co. Ltd. Price L2.50; $8.30. Merrow Pp. viii + 104. 1975.Copper Metallurgy : Practice and Theory. Papers Presented at a Meeting Organized by the Institution of Mining and Metallurgy with the Cooperation of the Centre Belge d’Information du Cuivre, and Held in Brussels, Belgium, on 11 February, 1975. Edited by M. J. Jones. Pp. vi + 83. London: The Institution of Mining and Metallurgy. 1975. Price A8. Computers for Spectroscopists.Members of the Ultraviolet Spectrometry Group. Edited by R. A. G. Carrington. Pp. xiv + 275. London: Adam Hilger Ltd. 1974. Price k12. AbrBg6 de Chimie (P.C.E.M.) Tome 1. Technique of Electroorganic Synthesis. Chimie GknBrale. Edited by Norman L. Weinberg. Techniques Edited by G. Germain and R. Mari with the Pp. x + 197. collaboration of D. Burnel. Pp. xiv + 274. New York, London, Sydney and Toronto: Paris: Masson & Cie.1975. Price 36F. John Wiley & Sons. 1974. Price f120. of Chemistry, Volume V , Part I .July, 1975 PUBLICATIONS RECEIVED 21 3 Electroanalytical Chemistry. Edited by H. W. Nurnberg. Advances in Analy- tical Chemistry and Instrumentation, Volume 10. Pp. xii + 609. London, New York, Sydney and Toronto: John Wiley & Sons. 1974.Price f;l8.50. Methods of Biochemical Analysis. Volume 22. Edited by David Glick. Pp. viii + 567. New York, London, Sydney and Toronto: John Wiley & Sons. 1974. Price fT13.50. Environmental Chemistry. Volume 1. Specialist Periodical Report. Senior Reporter: G. Eglinton. Pp. xii + 199. London : The Chemical Society. 1975. Price fT7- IP Standards for Petroleum and its Pro- ducts.Part 1. Methods for Analysis and Testing. Thirty Fourth Edition. Section 1, IP Methods 1-185; Section 2, IP Methods 186-323, Specifications, Appendices and Index. Two Volumes. Barking: Applied Science Publishers Ltd., on behalf of the Institute of Petroleum. 1975. Price fT12.50. Analytical Methods Applied to Air Pollution Measurements. Edited by Robert K. Stevens and William F.Herget. Pp. viii + 303. Ann Arbor, Michigan: Ann Arbor Science Publishers Inc. Distributed by John Wiley & Sons Ltd. : New York, Sydney, Tokyo, Mexico City and London. 1974. Price fT9-80. Official Methods of Analysis of the Associa- tion of Official Analytical Chemists. Twelfth Edition. Edited by William Horwitz. Pp. xxii + 1094. Washington : Association of Official Analytical Chemists.1975. Price $41. Chemical Phase Analysis. Roland S. Young. Pp. viii + 138. London and High Wycombe: Charles Griffin & Co. Ltd. 1974. Price fT4-50. 1974 Annual Book of ASTM Standards. Part 31. Water. Pp. xx + 902. Philadelphia: American Society for Testing and Materials. 1974. Price f126-50. Atomic Absorption Spectrometry. Edited by Maurice Pinta. Translated by K.M. Greenland and F. Lawson. Pp. xxii + 418. London: Adam Hilger Ltd. 1975. Price fT35. Biochemical Spectroscopy. Richard A. Morton. Volume 1. Pp. xvi + 1-381. Volume 2. Pp. iv + 382-873. London: Adam Hilger Ltd. 1975. Price fT80. Wilson and Wilson’s Comprehensive Analy- tical Chemistry. Volume 111. Elemental Analysis with Minute Samples. Standards and Standardization. Separations by Liquid Amalgams.Vacuum Fusion Analysis of Gases in Metals. Electro- analysis in Molten Salts. Edited by G. Svehla. Pp. xvi + 399. Amster- dam, Oxford and New York: Elsevier Scientific Publishing Company. 1975. Price Dfl125; $51.95. Atomic Fluorescence Spectroscopy. I. RubeSka, V. Svoboda and V. Sychra. Van Nostrand Reinhold Series in Analytical chemistry. Pp. 379. London, New York, Cincinnati, Toronto and Melbourne : Van Nostrand Rein- hold Company.1975. Price fTl2. Absorption Spectra in the Ultraviolet and Visible Region. Edited by L. LAng. Volume XIX. Pp. 400 (loose-leaf). Budapest : Akadkmiai Kiadb. 1974. Price fT8.75. Handbook of Reactive Chemical Hazards. L. Bretherick. Pp. xx + 976. London: Butterworths. 1975. Price f120. Chemical Analysis of Ecological Materials. Stewart E. Allen, H. Max Grimshaw, John A. Parkinson and Christopher Quarmby. Pp. x + 565. Oxford, London, Edinburgh and Melbourne : Blackwell Scientific Publications. 1974. Price fT12-50. Chemical Methods of Rock Analysis. Second Edition. P. G. Jeffery. International Series of Mono- graphs in Analytical Chemistry, Volume 36. Pp. xx + 525. Oxford, New York, Toronto, Sydney and Braunschweig : Pergamon Press. 1975. Price $37.50; k16.

ISSN:0306-1396    

DOI:10.1039/AD975120212b

出版商:RSC    

年代:1975

数据来源: RSC