ISSN:0144-557X    

DOI:10.1039/AP98522FX009

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

In an attempt to ensure that major developments in chemistry reach as wide an audience as possible RSC has made available reprints of important reviews which were published in RSC Journals Modern Analytical Methods for Environmental Polycyclic Aromatic Standardised Thin-Layer Rep ri n ts of Important Analytical Chemistry Reviews Chromatographic Systems for the identification of Drugs and Poisons by A. H. Stead, R. Gill, T. Wright, J. P. Gibbs, A. C. Moffat The October '82 issue of The Analyst featured a review of this area entitled Standardised Thin-Layer Chromatographic Systems for the Identification of Drugs and Poisons. The wide use of TLC for the analysis of drugs and poisons in biological fluids and pharmaceutical preparations suggests that this article will be of great interest t o many analysts working in the field.Consequently, The Royal Society of Chemistry has decided to make separate reprints available. Coverage This review gives criteria for good systems and applies them to the selection of the eight most effective. The selected systems are standardised by the use of standard running conditions and the use of reference compounds. Rf x 100 values are given for 594 basic, 48 neutral and 152 acidic drugs on the selected systems both in alphabetical order and ascending order of Rf for each system to aid the identification of unknown drugs. Further identification is enhanced by the inclusion of various locating procedures. Price f5.75 ($1 1.50) Prices inclusive of p & p to UK and European destinations and Surface Mail outside Europe.Airmail outside Europe at Compounds by K. D. Bartle, M. L. Lee, S. A. Wise Polycyclic aromatic compounds are major pollutants of the environment, originating from many sources. This paper reviews the techniques that are available for identification and analysis and provides the reader with a comprehensive and authoritative source of information on the subject. The paper is divided into the following sections: Introduction; Sample Preparation; Chromatographic Methods; Mass Spectrometry; Spectroscopic Methods. The review, which contains more than 400 references, will be of interest to environmental, petroleum and analytical chemists. Price f2.50 ($5.00) cost. To order the above reprints please send payment and a self addressed envelope measuring 6 x 9" minimum to: The Royal Society of Chemistry, The University, NOTTINGHAM NG7 2RD, England.

ISSN:0144-557X    

DOI:10.1039/AP98522BX011

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 57 Reports of Meetings South East Region The tenth Annual General Meeting of the Region was held at 1.55 p.m. on Thursday, December 6th, 1984, at King’s College, Strand, London. The Chair was taken by the Chairman of the Region, Mr. H. I . Shalgosky. The following office bearers were elected for the forthcoming58 ANALYTIC :AL PROCEEDINGS, MARCH 1985, VOL 22 year: Chairman-Mr. H. I. Shalgosky. Vice-Chairman-Mr. G. F. Phillips. Honorary Secretary-Dr. A. H. Andrews, Beecham Pharmaceuticals, Clarendon Road, Worthing, West Sussex BN14 8QH. Honorary Treasurer-Mr. W. B. Chapman. Honorary Assistant Secretary-Mr. P. J. O’Neil. Members of Committee-Professor D. Betteridge, Mr. D. Blair, Dr. J. E. Firth, Mr. R. Goulden, Mr. D. W. Houghton, Dr.S. J. Lyle (ex officio) and Dr. A. Ware. Dr. J. E. Page and Mr. D. C. M. Squirrel1 were re-appointed as Honorary Auditors. Microchemical Methods Group The forty first Annual General Meeting of the Group was held at 1.50 p.m. on Thursday, December 6th, 1984, in the Council Room, Kings College, The Strand, London. The Chair was taken by the Chairman of the Group, Professor D. T. Burns. The following office bearers were elected for the forthcoming year: Chairman-Dr E. J. Newman. Vice- Chairman-Professor D. T. Burns. Honorary Secretary-Mr. P. R. W.- Baker, 55 Braemar Gardens, West Wick- ham, Kent BR4 OJN. Honorary Treasur- er-Mr. M. R. Cottrell. Members of Committee-Mr. P. G. Baker, Mr. R. Goulden, Mr. P. Gabbott, Mr. J. Mend- ham, Mr. B. T. Saunderson and Mr. C.A. Watson. Mr. S. Bance and Mr. H. I. Shalgosky were re-appointed as Honorary Auditors. Biological Methods Group The fortieth Annual General Meeting of the Group was held at 6 p.m. on Tuesday, November 27th, 1984, at the Royal Society of Chemistry, Burlington House, London, W. 1. The Chair was taken by the Vice-chairman of the Group, Mr. D. Sykes. The following office bearers were elected for the forthcoming year: Chairman-Mr. D. Sykes. Vice- Chairman-Dr. A. H. Thomas. Honor- ary Secretary-Mr. A. J. Crooks, Vac- cine Research and Production Labor- atory, PHLS Centre for Applied Micro- biology and Research, Porton Down, Salisbury SP4 OJG. Honorary Treasurer- Dr. L. Singleton. Honorary Assistant Secretary-Mr. G. A. Sabey. Members of Committee-Mr. I. Anderson, Dr.M. E. Duncan and Mr. D. Hossack. Dr. J. H. Hamence and Dr. M. Parkes were reap- pointed as Honorary Auditors. Special Techniques Group The fortieth Annual General Meeting of the Group was held at 12.20 p.m. on Thursday, December 6th, 1984, in the Council Room, Kings College, The Strand, London. The Chair was taken by the Chairman of the Group, Dr. A. F. Taylor. The following office bearers were elected for the forthcoming year: Chair- man-Dr. A. F. Taylor. Vice- Chairman-Dr. J. F. Alder. Honorary Secretary-Mr. J. Huddleston, Building 10.2, Instrumentation and Applied Physics Division, AERE, Harwell, Did- cot, Oxfordshire OX11 ORA. Honorary Treasurer-Mr. A. G. Ferrige. Members of Committee-Professor A. Bailey, Dr. R. Belchamber, Mr. J. T. Davies, Mr. P. Hampson, Dr.C. M. Jenden, Dr. K. J. Saunders (Automatic Methods Group representative), Dr. L. W. Tetler and Mr. R. Whitaker. Dr. D. M. Christopher and Professor J. N. Miller were re-appointed as Honorary Auditors. Atomic Spectroscopy Group The twentieth Annual General Meeting of the Group was held at 2 p.m. on Tuesday, December 4th, 1984, at the Geological Society, Burlington House, London, W. 1. The Chair was taken by the Chairman of the Group, Dr. E. J. New- man. The following office bearers were elected for the forthcoming year: Chair- man-Professor A. Townshend. Vice- Chairman-Mr. N. W. Barnett. Honor- ary Secretary-Mr. D. J. Willis, Hilger Analytical Ltd., Westwood, Margate, Kent CT9 4JL. Honorary Treasurer-Dr. G. B. Marshall. Honorary Assistant Sec- retary-Mr.C. A. Watson. Members of Committee-Dr. A. A. Brown, Dr. A. R. Date, Mr. M. Davies, Dr. D. A. Hick- man, Mr. P. W. Hurley, Dr. J. Marshall and Dr. E. J. Newman (ex oficio). Mr. R. P. Blackmore and Mr. D. B. Ratcliffe were reappointed as Honorary Auditors. Chromatography and Electrophoresis Group The twentieth Annual General Meeting of the Group was held at 1.45 p.m. on Wednesday, December 19th, 1984, at the Pharmaceutical Society of Great Britain, 1 Lambeth High Street, London, S.E.l. The Chair was taken by the Chairman of the Group, Dr. R. M. Smith. The follow- ing office bearers were elected for the forthcoming year: Chairman-Dr. R. M. Smith. Vice-Chairman-Dr. R. G. Hop- kins. Honorary Secretary and Treasurer- Dr. D. Simpson, Analysis For Industry, Factories 2/3, Bosworth House, High Street, Thorpe-le-Soken, Essex C016 OEA.Members of Committee-Dr. F. K. Butcher, Dr. A. F. Fell, Dr. P. J. Hough- ton, Mr. N. G. McTaggart (co-opted), Dr. R. Patience and Dr. F. Smith. Mr. L. Fernandes and Dr. G. Mitchell were appointed as Honorary Auditors. Particle Size Analysis Group The nineteenth Annual General Meeting of the Group was held at 2 p.m. on Wednesday, December 5th, 1984, at the Linnean Society, Burlington House, Lon- don, W.1. The Chair was taken by the Chairman, Dr. R. Wilson. The following office bearers were elected for the forth- coming year: Chairman-Dr. N. G. Stanley-Wood. Vice-Chairman-Mr. P. J. Lloyd. Honorary Secretary and Treasurer-Mr. J. E. C. Harris, Director- ate of Quality Assurance, Technical Sup- port, Puriton, Bridgwater, Somerset TA7 8AD.Honorary Assistant Secretary-Dr. N. A. Orr. Members of Committee-Dr. L. P. Bayvel, Mr. G. Butters (co-opted), Mr. R. E. Buxton (co-opted), Mr. R. W. Lines, Dr. A. Rood, Mr. A. van Santen, Mr. J. P. K. Seville and Dr. R. Wilson. Mr. P. W. Shallis and Mr. J. Spence were re-appointed as Honorary Auditors. Scottish Region The fiftieth Annual General Meeting of the Region was held at 5 p.m. on Friday, November 9th, 1984, at the Royal Society of Edinburgh, George Street, Edinburgh. The Chair was taken by the Chairman of the Region, Dr. G. A. Best. The follow- ing office bearers were elected for the forthcoming year: Chairman-Dr. A. F. Fell. Vice-Chairman-Dr. D. E. Wells. Honorary Secretary-Dr. J. Warren, Department of Pathological Biochem- istry, Royal Infirmary, Glasgow G4 OSF. Honorary Treasurer-Dr.M. Masson. Honorary Assistant Secretary-Dr. M. Adams. Member of Committee-Dr. R. I. Aylott, Dr. G. A. Best (ex oficio), Dr. T. Lowther, Dr. J. Marshall, Dr. A. Row- ley, Dr. P. Smith and Dr. P. Stevens. Dr. R. A. Chalmers and Dr. J. E. Whitley were appointed as Honorary Auditors. Western Region The thirtieth Annual General Meeting of the Region was held at 6 p.m. on Friday, December 14th, 1984, at the Two Rivers Hotel, Chepstow. The Chair was taken by the Chairman of the Region, Mr. E. B. Reynolds. The following office bearers were elected for the forthcoming, year: Chairman-Mr. E. B. Reynolds. Vice- Chairman-Dr. P. Tackla. Honorary Sec- retary and Treasurer-Mr. F. W. Sweet- ing, Wessex Water Authority, Bristol Avon Division, P.O. Box 95, The Ambury, Bath BA1 2YP. Members of Committee-Dr. L. C. Ebdon, Mr. J. G. Jones (ex officio), Mr. G. F. Lewis, Dr. G. Nickless and Dr. J. D. R. Thomas. Mr. E. A. Hontoir and Mr. E. Minshall were appointed as Honorary Auditors. Northern Ireland Region The fourth Annual General Meeting of the Region was held at 5.15 p.m. on Wednesday, October 17th, 1984, in the Chemistry Department, Queen’s Univer- sity, Belfast. The Chair was taken by the Chairman of the Region, Dr. M. A. Leonard. The following office bearers were elected for the forthcoming year: Chairman-Dr. G. Svehla. Vice-Chair- man-Professor D. Thorburn Burns. Honorary Secretary and Treasurer-Mr. W. J. Swindall, Department of Che- mistry, David Keir Building, Queen’s University, Belfast BT9 5AG. Members of Committee-Mr. E. L. Donaldson, Mr. R. A. Hall, Dr. M. A. Leonard (ex oflicio). Mr. V. L. Beavis and Mr. C. Wilson were re-appointed as Honorary Auditors.

ISSN:0144-557X    

DOI:10.1039/AP985220057b

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 59 Regional History The Scottish Region of the Analytical Division of the RSC (formerly The Scottish Section of the Society of Public Analysts and Other Analytical Chemists) The first mention of the Scottish Section SOCIETY.-The Council has approved communicate with Dr. Tocher of Aber- in the pages of The Analyst of April 1935, in principle the formation of a Scottish deen on the Subject.” as part of the Annual Report of Council Section of the Society on the lines of the The minutes of Council report the presented at the Annual General Meeting North of England Section. The Council reading of a letter from Dr. Tocher, of the Society on March 6, 1935, states: hopes that Scottish members will lend advocating the formation of a Scottish “PRQPOSED NEW SECTION OF THE their full support to the scheme and will section and giving detailed reasons for60 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 the formation of this section.Council declined to give final sanction until Dr. Tocher had made full arrangements and drawn up the Bye-Laws. The Council also noted that the Society’s Bye-Laws would have to be altered. The minutes book of the Scottish Sec- tion begins with an account of the “Second Inaugural Meeting,” held in the North British Station Hotel, Edinburgh, on Thursday April 25th, 1935, at 5.30 p.m. The meeting discussed the proposed local rules, which had been drafted by Dr. Tocher and Mr. Andrew Dargie, along similar lines to those of the North of England Section. Some changes were made, then it was agreed that the rules would be submitted to the parent body.Dr. Tocher proposed that Mr. R. T. Thomson, who, at 80, was the oldest member of the Society present, should be the first Chairman of the Section. In due course Council approved the formation of the Section, and also approved the rules, which were to be common to all existing and any future sections. A grant of f10 was made towards the founding of the Section. At a subsequent committee meeting, the com- mittee approved payment of f5 11s to Dr. Tocher, “being his initial outlay in raising the Section.” The official first meeting of the Section was held on Wednesday November 13th, 1935, at 8 p.m. in the Grosvenor Res- taurant, Gordon Street, Glasgow. Sixteen members were present, along with the President, Hon.Secretary and Treasurer of the Society, and the Chairman of the North of England Section. Mr. R. T. Thomson, the Scottish Section Chairman, welcomed the members of the new Sec- tion and their visitors, then went on to remind members that it was their duty to prepare and read papers before the Sec- tion, as it was only in that way that the Section could flourish. He then read a paper himself on “Some Reactions of Sodium Hexametaphosphate.” Mr. J. B. McKean, the Hon. Secretary, also gave a paper. (Note. Mr. McKean celebrated 60 years of membership of the RSC in February, 1984.) That is the official record of the forma- tion of the Section, but there must obvi- ously have been a “First Inaugural Meet- ing,” so when was it? And who was Dr. Tocher? The Analyst evidently thought that all the Scottish members were acquainted with him.It seems that there had been in exis- tence since 1903 an Association of Public Analysts of Scotland, the members of which were all public Analysts and Of- ficial Agricultural Analysts practising in Scotland. This small association, of not more than about 12 members, met twice yearly, in May and November, the venue alternating between the Central Hotel, Glasgow, and the North British Hotel, Edinburgh. At these meetings only professional matters were discussed, but not scientific papers or papers dealing with methods of chemical analysis. The actual date of the first inaugural meeting appears to be lost now, but it almost certainly took place in November 1934 in the Central Hotel, Glasgow, because that would be the time and place for the second meeting of the Association of Public Analysts of Scotland for that year (since all the members of the Asso- ciation were also members of the Scottish Section, the meetings of the two were often arranged to take place on the same date at the same place, but at different times).After the two “inaugural” meetings, some of the members of the embryo Section (Dr. Drinkwater and Messrs. McKean, Jamieson and Dryerre) attend- ed the 6th Summer Meeting of the North of England Section at Harrogate on June 21-24, 1935. This allowed discussions to take place with the Officers present. Many of the Scottish members continued to attend these summer meetings at Blackpool, Harrogate and Scarborough, and have happy memories of them.It was not hard to find out about Dr. J. F. Tocher; he was an outstanding scientist with a wide range of interests. It would need a book to do full justice to his career; a short account of it is given in a separate article as part of our series on pioneers in analytical chemistry. Mr. R. T. Thomson (the Chairman) was a partner in the Glasgow firm of R. R. Tatlock and Thomson, Analytical and Consulting Chemists (which still exists today). He was a practical analyst with very wide-ranging interests and experience, related especially to the needs of Scottish industry. He w.as the originator of the well known method for titration of boric acid in the presence of glycerol or mannitol. The reports of the Section meetings, in The Analyst, give some idea of the wide range of interests of the members.Indeed, many subjects are still areas of active research today. The usual format for the meetings was for the members to dine together before getting down to the scientific business. Favourite meeting places were the Ca’doro Restaurant, 122 Union Street, Glasgow, the Central Sta- tion Hotel, Glasgow, the North British Hotel, Edinburgh, the Rhul Restaurant, 123 Sauchiehall Street, Glasgow, and the Bath Hotel, 154 Bath Street, Glasgow (which was just beside the offices of Tatlock and Thomson). In the years following 1945, there is evidence of the increasing interest of members in “Modern Instrumental Methods” such as spectrophotometry and spectrography (1946), adsorption chrom- atography (1949), polarography (1951), electrophoresis (1952), infrared spectro- scopy (1954), gas - liquid chromatography (1955) and flame photometry (1956).However, there was still much interest in classical methods. An interesting note appears in the minutes for the 1947 (12th) AGM, stat- ing: “Mr. M. Herd expressed concern at the difficulty experienced in obtaining supplies of chemical apparatus from retailers and manufacturers within a reasonable period. In the case of special apparatus, e.g., “Quickfit,” the delivery time was 18 months to 2 years from date of order. This state of affairs was of course due to the fact that production was almost entirely earmarked for export. It was decided to approach the parent society and ask them to make representation to the appropriate authority in the hope that something could be done to increase supplies to the Home Market.” By the next AGM, the position was still unsatis- factory-even filter funnels and beakers were difficult to obtain.In the early years of the Section, most of the papers were presented by the members themselves, but gradually over the years, and particularly after the parent society started to provide some funds, it became more common to have speakers invited to come and lecture on particular topics. Thus, the programmes began to mirror the development of analytical chemistry as a whole, rather than just the interests of analysts working in Scotland. It would be tedious to look at the programmes for all the 50 years of exist- ence of the Scottish Section, or the Scottish Region as it is known now, but some highlights can be mentioned.First, however, something should be said about the various changes of name that have occurred. The parent society had orig- inally been known as “The Society of Public Analysts,” but in 1907 it was changed, so that at the time of the formation of the Scottish Section, it was known as “The Society of Public Analysts and Other Analytical Chemists.’’ The Scottish members (like many others) did not like this name, to the extent that the very first Annual General Meeting passed unanimously a motion that “This meeting after careful discussion considers that the name of the Parent Society should be altered to a less cumbersome title, and suggests for the consideration of the Council that the title should be ‘The Society of Analytical Chemistry’.” Even- tually, in 1953, a change was made to “The Society for Analytical Chemistry,” or SAC for short.Then, in 1972, the SAC took part in an amalgamation, as a result of which it became the Analytical Divi- sion of the Chemical Society: this change only became final in 1975, the year after the original Society celebrated its Cente- nary. It was with this amalgamation that the Scottish Section became the Scottish Region, because the Chemical Society used the term “Section” for rather smaller geographical regions than the old SAC Sections. The final name change cameANALYTICAL PROCEEDINGS. MARCH 1985, VOL 22 61 with the full unification of the Chemical Society with the Royal Institute of Chemistry, to form the Royal Society of Chemistry, in 1980.Thus, the original Scottish Section of the Society of Public Analysts and Other Analytical Chemists has now become the Scottish Region of the Analytical Division of the Royal Society of Chemistry. Many of the highlights of the pro- gramme over the years have been joint meetings with other Societies, and with other Groups and Regions of our own Society. Such meetings have always proved popular. Joint meetings have also been held frequently with the various students’ chemical societies at the Scottish Universities. The first ever joint meeting was held in conjunction with the Food Group of the Society of Chemical Industry, on January 22nd, 1936. Other oustanding joint meetings have included: “Spectrophotometry and Spectroscopy,” with the Physical Methods Group, on May 23rd, 1946; “The Principles of Chro- matography,” by R.L. M. Synge (1952 Nobel Laureate), with the Stirlingshire sections of the RIC and SCI; “Gas Chro- matography,” with the Physical Methods Group, on May 20th, 1955; “The Use of Radioactive Materials in Biological Assay,” with the Biological Methods Group, the Physical Methods Group and the Edinburgh Sections of the RIC, SCI and CS, on July llth-l2th, 1955; “Modern Aspects of Electroanalytical Chemistry,” with the Physical Methods Group, on May loth, 1963; “Atomic Absorption Spectrophotometry,” with the Atomic Absorption Spectroscopy Group, on April 3rd4th, 1968; “Trace Analysis,” with the North East Region and the Atomic Spectroscopy and Radio- chemical Methods Groups, on June 24th- 27th, 1970; and many more in recent years, particularly on HPLC, GC - MS, Atomic Spectroscopy, Automation and Microcomputers, Aspects of Clinical Analysis, etc., often in association with the Association of Clinical Biochemists.Other outstanding meetings organised by the Scottish Section or Region have included a highly successful “Congress on Modern Analytical Chemistry in Industry,” held at St. Andrews on June 24th-28th, 1957. This meeting was greatly oversubscribed: 299 participants were registered, 70 applications were refused, and an early announcement of the closure of registration prevented perhaps 2-300 more applications. An even greater indi- cation of the meeting’s success is the fact that all of the participants attended prac- tically every lecture. Another successful meeting was one organised at very short notice by the Section, in honour of Professor Cecil Wilson.This Inter- national Symposium, known as the “Bel- fast” meeting, because it should have been held there but for the Irish “troubles,” attracted participants from many countries. One abiding memory of Glasgow, March 22nd-25th, 1972, must be the whisky-tasting party, with the unforgettable accompaniment of Scottish dance music played on an incredibly out-of-tune piano. Finally, the SAC 83 International Conference, held in Edin- burgh on July 17th-23rd, 1983, must be mentioned. The major work of organis- ation of this event was done by members of the Scottish Region, with Professor J. M. Ottaway as Chairman of the Steering Committee and Dr. J. E. Whitley as Chairman of the Local Committee. A memorable dinner was held in NoverlSer 1974, to celebrate the 40th AGM of the Rqion.It was attended, from London, by Miss Pam Hutchinson, the Society’s Secretary, who had then recently completed 21 years’ service with the Society, and by Mr. David Wilson, who spoke on behalf of the President about the decision taken the previous week to go ahead with “amalgamation.” The occasion became therefore some- thing of a wake for the “old” Society for Analytical Chemistry, with reminiscences from Dr. D. M. W. Anderson and Dr. R. A. Chalmers. However, John Ottaway made it clear that the Scottish Region intended to play a full and active role in the “new” Analytical Division of the CS. There have been many notable analy- tical chemists among the membership of the Scottish SectiodRegion.Dr. Tocher has already been mentioned; many more are included in the list of Office-Bearers given in Table 1. The best-known to the general public is probably Dr. Magnus Pyke, who, after his retirement from Distillers Co. Ltd. at Menstrie, managed to make a new career for himself as a television personality, famous for wild gestures with hands and arms. The late Professor Ron Belcher was briefly a member when he was a lecturer at Aber- deen University. Professor T. S. West, who was his student then, returned to Aberdeen in 1975 after having built up a large analytical group at Imperial Col- lege, to become Director of the Macaulay Institute, in succession to two other eminent analytical chemists, Professor D. N. McArthur and Dr.R. L. Mitchell. The Macaulay Institute also provided a Society Gold Medallist in Dr. R. C. MacKenzie. Dr. Christina Miller, then Senior Lecturer in Analytical Chemistry at Edinburgh University, took a keen interest in the Section, although she did not hold office. Dr. Miller, a most talen- ted and versatile chemist (she had done research in physical, organic, inorganic and analytical chemistry) was a terror to students, but was really most kind- hearted and considerate, with an un- swerving devotion to truth and chemistry. When a certain professor remarked that analysts sometimes “cooked” results, Chrissie muttered “Let him speak for himself!” She will alwavs be well remem- bered by those she taught; among these were Dr. Bob Chalmers and Dr. John Hunter, who both became Chairman of the Section. Special mention must be made of Professor John Ottaway, who has become a pillar of the SectiodRegion, and indeed of the Parent Society.He was an energetic Secretary, an enthusiastic Chairman, and was the person mainly responsible for bringing SAC 83 to Edin- burgh. He has an outstanding reputation as an Analytical Chemist, recognised by the 2nd SAC Silver Medal in 1974 and the 17th SAC Gold Medal in 1984, by his election as a Fellow of the Royal Society of Edinburgh, and by his appointment to a Chair by the University of Strathclyde. In addition, he is the Chairman of the RSC Analytical Editorial Board. Another Silver Medal has come to Scotland Table 1. Officer-Bearers of the Scottish Sec- tion/Region Chairman Honorary Secretary 1935 R.T. Thomson J. B. McKean 1936 1937 J. F. Tocher 1938 1939 T. Cockburn 1940 1941 J. W. Hawley 1942 1943 A . R. Jamieson R. S. Watson 1944 1945 J. B. McKean 1946 1947 H. Dryerre 1948 1949 J. Sword 1950 1951 H. C. Moir 1952 1953 R. S. Watson 1954 1955 F. J . Elliot 1956 1957 M.Pyke 1958 1959 A . N. Harrow J. Brooks 1960 1961 A. F. Williams 1962 1963 R. A . Chalmers J. W. Murfin 1964 1965 J . K. McLellan 1966 1967 J . W. Murfin B. B. Darlow 1968 J. M. Ottaway 1969 D . M. W, Anderson 1970 J. A . Hunter 1971 1972 W. Dunnet 1973 1974 J. M. Ottaway 1975 1976 A.M.Ure 1977 A. F. Fell 1978 G . Cochrane 1979 1980 J. E. Whitley 1981 1982 G.Best D. E. Wells 1983 J. A . Eggleston J . E. Whitley62 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 recently, to Dr.Malcolm Cresser, of the Soil Science Department at Aberdeen University. Professor John Knox of Edin- burgh University is another most distin- guished member of the Region. Although he has never served on the committee, he has been of great assistance in many ways over the years. It was most pleasing, therefore, to learn that he has recently been elected a Fellow of the Royal Society. The membership of the Section in 1935 was 30, by 1945 it was 51, and by 1956 it had reached around 100. It stayed at about that level until “amalgamation” in 1972 brought in many new members who had previously been members just of the Royal Institute of Chemistry or The Chemical Society; the membership in 1974 was just over 400, and it has remained at much the same level until the present.There must be a question in the minds of some readers about why, if the 1st AGM took place in 1936, the 50th occurred in 1984. The explanation is that in 1970 a decision was taken to change the date of AGMs from January to Novem- ber. As a result, the 35th AGM was held on January 23rd, 1970, and the 36th on November 6th, 1970. Thus, by a happy chance, we celebrated in 1984 not only the 50th AGM, but also the 50th anniversary of the very first “inaugural” meeting of the Section. MARY R. MASSON Health and Safety in the Chemical Laboratory - Where do we go from here? This publication provides an overview of health and safety developments in the chemical laboratory and workplace, and will provide essential reading for anyone involved in these areas. Brief Contents: Accident and Dangerous Occurrence Statistics in the United Kingdom; Morbidity and Mortality Studies; Economics of Health and Safety Measures; Procedures and Statistics in France; Professional Negligence, Liability and Indemnity; The System in the United States of America; The System in the United Kingdom; The System in the Federal Republic of Germany; Hazards of Handling Chemicals; Hazards of Apparatus, Equipment and Services; Managing People; What Standards Should We Use? Conflict of Safety Interests with Legislation; The Protection of Workers Exposed to Chemicals: the European Com mu nity Approach; Recommendations Arising from the Symposium. Special Publication No. 51 Softcover 206pp 0 85186 945 9 Price f 16.50 ($30.00). RSC Members f 12.00 Ordering: Non-RSC Members should send their orders to: The Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 1 HN, England. RSC Members should send their orders to: The Royal Society of Chemistry, Membership Officer, 30 Russell Square, London WClB 5DT. The Royal Society of Chemistry Burlington House, Piccadilly London W1V OBN

ISSN:0144-557X    

DOI:10.1039/AP985220059b

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 63 Novel Instrument Design in Atomic Spectroscopy The following are summaries of four of the papers presented at a Joint Meeting of the Scottish Region and Automatic Methods Group held on May 2nd-3rd, 1984, at the University of Strathclyde, Glasgow. Grating or Fourier Spectrometers: Which and Why? Anne Thorne Blackett Laboratory, Imperial College, London S. W. 7. Introduction Most papers on novel instrument design in atomic spectroscopy are concerned with the emission source and take for granted the spectrometer. In this paper I shall take the source for granted and concentrate on the spectrometer; what do we want it to do and how well does it do it? I am therefore concerned with problems that are difficult in the spectroscopic sense, for example the rare earths, where there is a large degree of spectral overlap, or the determination of trace elements.Both of these are problems in which the spectral resolution is critical, and I shall start with a few general remarks about this topic. I shall then explain briefly how Fourier transform spectroscopy works and try to convince you that a Fourier transform spectrometer (FTS) offers significant advantages over a grating for many such difficult problems. Resolving Power and Light Throughput Ideally one would like the instrumental line width 6hi to be at least as small as the true line width ah,, i.e., 6hiS 6h,. Clearly this condition minimises spectral overlap. What is not quite so widely appreciated is that it also improves the line to continuum discrimination.Perhaps I could explain this in the context of a grating spectrometer: if one starts with a slit width corresponding to 6hi = 6h,, the signal contains the whole of the line plus the continuum corresponding to the band width 6hi; opening the exit slit to 36h, gives the same line signal but triples the band width and hence the signal from the continuum. Obviously this could be an important consideration in detec- tion sensitivity. Yet another benefit of narrow instrumental width is illustrated by Fig. 1, which is part of an FTS run with an iron hollow cathode source using neon as the carrier gas. The iron and neon lines are clearly distinguishable by their very different widths. Note the logarithmic intensity scale and also the very weak iron line in the bottom right-hand corner, which would certainly be swamped’by its strong neon neighbour in a spectrum at lower resolution or lower signal to noise ratio.What resolving power are we talking about in practice? For the light sources used in analytical work, ahs is essential1 the Doppler width, which is given by (6h,/h) = 7 x 10-7 &, where T is the temperature and M the relative molecular mass. Thus, the condition 6hi - ah, requires a resolving power R (defined as h/6hi) in the range 105-106. The fundamental limitation on resolving power is that R is equal to the number of wavelengths in the extreme path difference A imposed by the instrument, either across the wavefront in a dispersive instrument or between corresponding 105 1 04 103 8 102 - -I 10 41 50 41 55 41 60 Waven u m ber/cm - 1 p-d p-d 105 1 04 103 - 102 10 41 25 41 65 41 70 4175 Waven u m ber/cm - Fig.1. Fourier transform atomic-emission spectrum. Source, iron hollow-cathode lamp; carrier gas, neon64 I I ANALYTICAL PROCEEDINGS, MARCH T-r 1 1985. VOL 22 Fig. 2. Illustration of path difference parts of the wavefront in an interferometer (see Fig. 2 ) , i.e. , R = A/h. This limitation can be derived directly from the uncertainty principle, or, if you prefer, the band width theorem. In an interferometer A depends only on the displacement of one mirror and is essentially unlimited, whereas for a grating it depends on the physical width W of the grating; in a Littrow-type mounting A - 2W sin 0 - W. For practical purposes R is therefore limited to a few hundred thousand.Furthermore, because a grating is a spatially dispersive device, the theoretical resolution can be realised only if the focal lengths of the collimating and focusing lenses or mirrors are sufficiently long, “long” meaning 3m for R approaching 105, increasing to 10m for 5 x 105. High resolving power must always be paid for with light grasp, and for a given type of instrument the product R x (light throughput) is a constant. It can be shown that an inter- ferometer with axial symmetry has a throughput some two orders of magnitude greater than that of a grating instrument of the same resolution. For example, for R = 105 one would need a 3-m grating spectrometer with a slit approximately 20 pm wide and lcm high. An FTS of the same resolution and the same input f-number would use a circular aperture 8mm in diameter and could be physically half the length. Fourier Transform Spectroscopy The FTS uses some variant of a Michelson interferometer in which the path difference, x , between the two beams is changed by scanning one mirror at velocity v.The signal at the detector, the inteferogram, from any one wavelength h is the with 253.7 nm 0.01 nm - I ‘I I ’’1 I Interferometer: A = 2 x grating instrument and interferometer usual two-beam interference sinusoid where the wavenumber o is defined as l/h. Becausex = 2vt, this can also be written as showing that the interferometer converts the true light frequency co to an audio frequency vo, proportional to o and adjustable by choice of v. For a source of spectral distribution described by B(o), the interferogram is the superposition of sinusoidal signals given by Z(x) = const. + Jr B(o) cos 2xox do Z(x) contains all the information on the source, and the spectrum is recovered by performing the Fourier transform Z(x) fx 1 + cos 2nox Z(t) 1 + cos 2n(2vo)t B(o) = JF Z(x) cos 2nox dx where L is the maximum path difference.It is L that determines the resolution; the resolving limit in wavenumbers is simply 60 = 1/L, consistent with the general considerations of the last section (6oi = 6hi/h2, so R = LA). In practice, of A- 5 500 - SiI: 221.1 nm showing self-reversal 45 220 45 230 Wavenum ber/cm - Fig. 4. Part of ultraviolet spectrum of neutral silicon, using silicon tetrachloride microwave discharge lamp (carrier gas, argon).The two spectra are obtained by Fourier transforming the same interferogram using first the central section only (low resolution) and secondly the whole interferogram (high resolution)ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 65 course, the interferogram is sampled at discrete intervals, and the FT is a sum rather than an integral. The sampling interval Ax determines the free spectral range; according to the Nyquist sampling theorem Ax must be less than half the minimum wavelength in the band if order overlap is to be avoided. An important characteristic of the FTS is that sampling is controlled by a laser, and all wavelengths are given in terms of that of the laser, thus providing a built-in wavelength scale. AES with the FTS? Fourier transform sepctroscopy has long been an established technique in the infrared region, and clearly it should offer substantial advantages in resolution and light grasp for atomic-emission spectroscopy in the visible and ultraviolet regions.Why then have these not been exploited? There are three main reasons. First, the FTS has an additional advantage in the infrared, where noise levels are set primarily by the detectors, by virtue of the large signal obtained by observing all wavelengths simultaneously. The improvement in signal to noise ratio that results is known as the multiplex advantage. The absence of this advantage at shorter wavelengths, where the noise is primarily source or photon noise, tends to be construed as a disadvantage; as a matter of fact the multiplex advantage does not disappear entirely for a line spectrum, given that a scanning grating spectrometer must necessarily spend some fraction of the available time scanning the “empty” bits of spectrum between the lines.Secondly, the FTS cannot operate without a computer. This drawback has become more apparent than real with the increasing power and availability and the decreasing cost of microcomputers, which are generally used both to control scanning spectrometers and to process the data from them. Thirdly, there are obvious mechanical problems associated with a scanning interferometer in the ultraviolet, because all tolerances scale with wavelength. That these problems are surmountable is demonstrated by Fig. 3, showing the mercury line at 253.7nm as obtained with the UV FTS at Imperial College; the full theoretical resolving power of 300000 is actually realised here, to the extent that the self-reversal in each of the hyperfine structure components of the line is resolved.It is therefore both possible and advantageous to replace a scanning spectrometer with an FTS for problems in which high resolution and good signal to noise are important. The FTS does indeed have two or three additional subsidiary advan- tages. It has an accurate built-in wavelength scale, it is insensitive to scattered light of a different wavelength, it is very flexible as regards resolution (Fig. 4 shows how a single interferogram can be used to give a wide spectral band at low resolution or any selected part at high resolution) and, because all information on the complete spectrum is automatically available from every scan, it opens up the possibility of determining concentrations from “fingerprint” spectra rather than from single lines.The FTS cannot compete with a polychromator for routine analysis or discrete sampling, but for non-routine, difficult problems, used in conjunction with continuous sampling in an ICP source for example, it offers exciting possibilities of improvements in both accuracy and sensitivity . Some Thoughts on Making the Best Use of Conventional Pneumatic Nebulisers in Flame Atomic-absorption Spectroscopy Malcolm S. Cresser Department of Soil Science, Aberdeen University, Aberdeen AB9 2UE In a symposium on novel instrument design in atomic spectroscopy, it seems appropriate to review briefly the recurrent problems associated with the routine use of conven- tional pneumatic nebulisers, with a view to assessing the likelihood of their being solved in the foreseeable future.For convenience the outstanding limitations associated with nebuli- zation may be subdivided into four categories: (i) limited useful transport efficiency; (ii) limited stability; (iii) inadequate understanding of fundamental mechanisms; and (iv) the occasional need for time consuming chemical pretreatment. It should be stressed that transport efficiency, i.e., the fraction of determinant element in the aerosol generated that reaches the flame, is not always a useful method for assessing pneumatic nebuliser performance. If the size distribution of aerosol entering the flame is such that volatilisation and atomisation are incomplete, then further increasing the amount of analyte reaching the flame without improving the droplet size distribution may only serve to increase the curvature of calibration graphs and also the susceptibility of the system to incomplete volatilisation interferences.Moreover, the excessive solvent loading in the flame may lead to increased noise and less favourable atomisation conditions. Thus only increases in usefuE efficiency should be sought. These are increases in transport efficiency that do not adversely influence the range of absorbance values over which calibration is linear. This parameter varies from element to element and even, for some elements, with the associated anion. Useful transport efficiency for a nebuliser - spray chamber - burner system can only be increased either by generation of a superior primary aerosol size distribution (achieved by improved nebuliser design), or by generation of additional aerosol with a similar size distribution, while at the same time improving the cut-off diameter of the impactor - spoiler - spray chamber combina- tion.In the latter instance, the additional larger droplets produced never reach the flame. It is appropriate here to consider the methods employed in atomic-absorption spectrometers to increase the amount of sample solution reaching the flame. Impact beads are often used and it is assumed, because they often increase total transport efficiency, that they improve the droplet size distribution of aerosol leaving the burner slit.However, there is little evidence to support this as a general hypothesis.1 Indeed, evidence obtained in the author’s laboratory indicates that the fragmentation of the film of liquid which forms over the bead surface from impacting droplets in the jet of air from the nebuliser produces a significant proportion of larger droplets. This is often clearly visible when the aerosol size distributions of aerosol are measured by the cascade impactor technique2 in the presence and absence of the bead. Indeed, many very large droplets may be produced. This may easily be demonstrated by lining the spray chamber walls with paper, and nebulising an intensely coloured dye solution, for example methylene blue, for a few seconds. The spray patterns thus produced clearly show the high impact loss around the circumference of the spray chamber a few centimetres from the nebuliser, even in the absence of the impact bead.In its presence, the size of the liquid droplets deposited is clearly very much greater. It is of interest that the aerosol passing the impact cup, a device designed deliberately to dump aerosol to obviate the need for 10-fold sample dilution,3 is all contained in droplets less than 3 pm in diameter. This explains why the impact cup gives much lower interference levels than the impact bead.3 A further advantage of the cup is that, unlike alternative methods of removing large droplets such as flow66 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 spoilers or extended spray chambers, it gives a very low flame solvent loading.Indeed, impact cups are probably highly suited to the introduction of organic solvent samples into ICPs. Another useful way of studying the breakup of the film of liquid on an impact bead surface is to introduce a flow of concentrated potassium solution via a capillary through the centre of the bead. If sodium solution is then sprayed through the nebuliser in the normal way, and the droplet size distribution measured with a cascade impactor, the relative distributions of sodium and potassium between the droplet size ranges show where the larger droplets are formed. Attempts to improve sample useful transport efficiency by pumping sample to the nebuliser at rates above the conven- tional nebuliser aspiration rate are invariably unsuccessful.The author and his colleagues have recently shown that nebuliser suction decreases with increasing aspiration rates once a certain, often fairly low, aspiration rate is exceeded.4 As suction is an important potential energy component of the nebulised solution, the resulting aerosol is inevitably less fine at higher aspiration rates. 1 Thus useful transport efficiency, and eventually even total transport efficiency, may actually dec- rease with increased sample introduction rate, to the point where the nebuliser eventually totally ceases to function. The stability of aerosol production is limited by any partial blockage or clearance of the aspiration and/or nebuliser capillaries. This instability may be continuous or intermittent. In a recent study concerned with the measurement of nebuliser suction, it was shown that the suction measured by a manometer4 or, more recently, by a pressure transducer, connected to the side arm of a T-piece in the aspiration line, could be used to calculate the nebuliser suction with liquid flowing.A correction must be made for the fall in suction along each section of capillary and for each connector which results in a change in tubing diameter. The correction factor derivation involves straightforward fluid mechanics,4*5 and the resulting equation for the suction fall (AP) takes the form AP = aQ + bQ2 where Q is the aspiration rate and a and b are constants for a given system. Generally a is much greater than b , so that at low to moderate pressures the bQ2 term becomes negligible, and A P K Q .Thus a manometer or a pressure transducer may be used to monitor the aspiration rate, Q, and immediate warning is obtained when Q drifts, for example, through changes in aspiration gas pressure or through partial nebuliser blockage. This reduces the frequency with which a suitable standard must be nebulised for the purpose of confirming nebuliser stability. Some preliminary work has been carried out, in which the pressure transducer and the atomic absorbance have been interfaced to a BBC-B microcomputer, and the atomic- absorbance signal is corrected continuously for drift in aspira- tion rate. The results have been encouraging, demonstrating clearly that even severe signal drift due to aspiration rate fluctuations through nebuliser blockage may be compensated for.Although concentric nebulisers have been in use in analytical atomic spectrometry for many years, our understanding of the fundamental mechanisms of aerosol production is still severely limited. Interest in aerosol size distributions in particular has grown greatly over the past 6 years, but most of the general conclusions which have been, or may be, drawn are based purely on empirical evidence rather than theoretical principles. Such empirical studies can be very useful, however, for assessing the effects of impact beads, flow spoilers, spray chamber geometry and auxiliary oxidant on the size distribu- tion of aerosol reaching the flame.’ The final problem remaining with pneumatic nebulisation - flame AAS is the occasional need to add releasing agents or ionisation buffers, or sometimes for dilution of samples.The latter may sometimes be avoided by employing an impact cup, as mentioned earlier.3 This approach is preferable to burner rotation or use of alternative wavelengths that give poorer sensitivity, because of the reduced incidence and extent of incomplete volatilisation interferences when the cup is used. Releasing agents and ionisation buffers may be added via capillary T-pieces connected to the nebuliser capillary. However, if the precision and accuracy are not to be adversely affected, then the heads of reagent and sample should be kept fairly constant, the T should be connected directly to the nebuliser capillary tip, small diameter aspiration tubing should be used (to eliminate a syphoning effect) and the lengths of tubing and the vertical distance between the diluent and sample surfaces should be minimised.6 Where pre-concentration is needed, and facilities for auto- mated solvent extraction are unavailable, evaporation at reduced pressure to achieve 10-fold concentration may be convenient, simple and rapid.7 Typically 24 1.5-ml samples in Technicon AutoAnalyzer sample cups may be concentrated 10-fold in a vacuum desiccator overnight over calcium chloride. Change in volume is assessed from mass loss, and the concentration factor thus calculated.The element of interest is then determined by the discrete sample nebulisation tech- nique .g Conclusions Major improvements in nebuliser design are improbable, but there is still scope for slight enhancements in useful transport efficiency through better designs of impactors, flow spoilers and spray chamber geometry.Continuous correction for drift in aspiration rate should be possible on a routine basis, and could prove to be a worthwhile development. There is still considerable scope for time saving by improving or eliminating separate sample pretreatment. The author is indebted to Clare O’Grady, Fiona Mitchell, Fiona Robertson, Rick Browner, Tony Edwards and Iain Marr for their contributions to this work, and to the SERC for financial support. 1. 2. 3. 4. 5. 6. 7. 8. References Cresser, M. S . , and Browner, R. F., Appl. Spectrosc., 1980,34, 3. Cresser, M. S., and Browner, R.’F., Spectrochim. Acta, Part B, 1980,35, 73. Cresser, M. S., Analyst, 1979, 104, 792. O’Grady, C., Marr, I. L., and Cresser, M.S., Analyst, 1984, 109, 1085. Holland, F. A., “Fluid Flow €or Chemical Engineers,” Edward Arnold, London, 1973. Cresser, M. S., and Edwards, A . C., Spectrochim. Acta, Part B, 1984, 39, 609. Robertson, F. A . , Edwards, A. C., and Cresser, M. S . , Analyst, 1984, 1-09, 1265. Cresser, M. S., Prog. Anal. At. Spectrosc., 1981, 4, 219.ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 67 Microcomputer Controlled Background Correction for ETA - AES and ETA - Continuum Source AAS J. Marshall, J. Carroll, D. Littlejohn and J. M. Ottaway Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G I 1XL T. C. O’Haver Department of Chemistry, University of Maryland, College Park, Maryland 20742, USA J. M. Harnly US Department of Agriculture, Nutrient Composition Laboratory, BA RC- East, Beltsville, Maryland 20705, USA The technique of electrothermal atomic absorption spec- trometry (ETA - AAS) is undergoing a period of substantial development.Progress is particularly evident in the area of atomiser design, where numerous modifications have been proposed to improve the analytical performance of Massmann- type systems.1-4 Indeed it has been suggested that the utilisation of this new atomiser technology will eliminate the majority of chemical interference effects encountered in ETA - AAS.5 Developments of equal significance are taking place in the design of instrumentation for ETA - AAS measurement. The background correction capability of a spectrometer is of considerable importance when an electrothermal atomiser is to be employed.In the majority of instruments, non-specific absorption and scatter of radiation from the primary light source (usually a hollow cathode lamp or EDL), by the matrix, is compensated for by the use of a secondary continuum source (deuterium or tungsten lamp). Careful spatial alignment of the two beams is necessary when using such a system, in order to achieve effective background correction. Difficulties in optical alignment are avoided if a single light source is used, as in the Smith - Hieftje6 and Zeeman-effect7 background correction systems, but decreases in sensitivity have been reported for some elements. Narrow line primary light sources have been almost exclu- sively used in atomic-absorption spectrometry since its incep- tion, effectively limiting thk technique to single-element analysis.It has been demonstrated, however, that a continuum source can also be satisfactorily utilised as the primary light source for atomic-absorption measurements, provided that a relatively high resolution spectrometer is employed.* Wavelength modulation, a rapid, repetitive scanning tech- nique, can be used to perform background correction in continuum source atomic-absorption spectrometry.9 As absorption line spectra are relatively uncomplicated, back- ground correction can be achieved by using the continuum radiation level on either side of the line profiles as a reference intensity for the absorbance calculation. The procedure is advantageous in that detection limits are improved when background correction is employed,’o and because only one light source is used, there are no optical alignment problems. This method of detection is particularly suitable in electrother- mal atomic absorption spectrometry (ETA - AAS), a tech- nique in which high background absorbances are often encountered.When used in conjunction with a suitable direct reading spectrometer the technique also offers the capability of simultaneous multi-element analysis by atomic-absorption spectrometry. 11 The application of electrothermal atomisers in atomic- emission spectrometry has been extensively investigated in the last 10 years. Electrothermal atomic emission spectrometry (ETA - AES) exhibits high sensitivity for many elements, and in this respect can be considered as a viable alternative to ETA - AAS.Wavelength modulation has been used to provide automatic background correction in ETA - AES, as the low operating temperature of the source gives rise to relatively simple spectra. It has been reported that the use o’f wavelength modulation also provides a significant improvement in ETA - AES detection limits. 12713 A recent investigation demonstrated the feasibility of simultaneous multi-element analysis by ETA - AES, using a PDP11/34 minicomputer for data acquisition and data processing.14 The wavelength modulation systems used for continuum-source atomic-absorption spectrometry and atomic-emission spectrometry are essentially the same. Thus, identical instrumentation can be used to measure ETA - AAS and ETA - AES signals.However, in a single-channel system it is possible, and indeed cost effective, to use a microcomputer such as an Apple for data processing purposes instead of a relatively expensive minicomputer. This paper describes briefly the characteristics of a purpose-built microcomputer- controlled instrument system that is suitable for both back- ground corrected ETA - AAS and ETA - AES measurement. Experimental The instrument system was based on a single-channel Spec- trametrics SMI I11 echelle spectrometer. A 5 mm thick quartz plate mounted on the shaft of a General Scanning Inc. G300PD torque motor was positioned behind the entrance slit of the monochromator in order to provide wavelength modulation. The output from the photomultiplier (Hamamatsu R292) was passed via a laboratory constructed preamplifier - attenuator to an Interactive Structures A113 12-bit ADC, which plugged into an expansion slot inside the Apple IIe microcomputer.The microcomputer was equipped with a high resolution mono- chrome monitor, twin disk drives and a dot matrix printer fitted with a Grappler interface. The movement of the quartz plate was controlled by the microcomputer via an Interactive Structures A003 8-bit DAC and a scanner controller. A 300-W Eimac xenon arc lamp was used as the light source for absorption measurements, the lamp being simply switched off when the emission mode was employed. A Perkin-Elmer HGA 500 electrothermal atomiser was used for both absorption and emission measurements. Commercially available pyrolytically coated graphite tubes were used throughout.Nitrogen was employed as the atomiser purge gas. A compromise atomisa- tion temperature of 2700°C was selected for all elements in both the absorption and emission modes. Data acquisition by the computer was triggered automatically by selecting the “read” function on the HGA 500 programmer in the appro- priate stage of the heating programme. Samples were intro- duced to the atomiser by use of a Perkin-Elmer AS-1 autosampler. Operational Procedure Data acquisition and data processing by the computer are achieved by using one of a set of compiled BASIC programs with an ASSEMBLY language sub-routine. Initially the system is booted by using a BASIC loading program, which offers the option of one of 12 operating program selections from a main menu.The options include the choice of atomiser (ETA or flame), mode of measurement (absorption or emission) and68 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 (a) ......... .- ........... Back$ rou nd CS ETA - AAS 50 ng ml-’ Cu y scale 0-0.5 A x scale 0-10 s ETA - AES 20 pl5 ng ml-1 Cr 425.4 nm . . . Background. .: I * a_y^ 2-s integration Fig. 1. Apple graphics plots of background corrected atomic-absorption and atomic-emission signals. The background level is indicated by the dotted line. ( a ) , Continuum source ETA - AAS signal for 20 p1 of 50 ng ml-1 copper solution; (b), ETA - AES signal for 20 pl of 50 ng ml-1 chromium solution modulation wave form (sine wave, 3-step square wave or 5-step square wave). Once the option has been selected, the appropriate compiled BASIC program is run and the informa- tion relating to the modulation wave form is stored in absolute memory.The selected program has its own experimental menu, which allows the various measurement conditions to be established. The user is asked for the name of the experiment, the element, the wavelength and the date. This information is automatically stored on disk in a file identified by the experiment name. The system employs two disks, one contain- ing the operating programs and the other to store experimental data. Other experimental details, such as integration limits, x and y axis scaling factors for the background corrected absorbance - intensity versus time graph and printer options, are then entered. The system waits for a trigger from the atomiser in order to begin data acquisition.The ASSEMBLY language routine is used to control the modulation unit and perform the data acquisition at acceptable speeds, whilst the main BASIC program is used to manipulate the raw data thus acquired in absolute memory. Integration limits can be selected between 1 and 500, which corresponds to a 0-10s interval at the normal operating frequency of 50 Hz. Calculations are made on the basis of the integration limits selected, but it is possible to re-process the data using alternative integration limits as the entire raw data buffer is retained until the next atomisation. This re-processing option has been found, in practice, to be a useful feature of the programme. The raw data is reduced to the essential informa- tion, i .e . , atomisation number for identification of the run, peak height and area values, and is saved on disk under the experimental file name. The results are displayed in the first instance on the VDU, but an option in the programme allows the generation of hard copy on a printer. In the present system, an Apple dot matrix printer is connected to the computer by means of a Grappler interface. Atomisation data are routinely dumped to the printer and this option is usually selected at the beginning of an experiment. In electrothermal atomisation, because of the transient nature of the signal it is often important to be able to inspect, and indeed record, the variation in absorbance or intensity with respect to time. For this reason, corrected signals and background levels are plotted automatically on the VDU after each atomisation.The x and y axes of the graph can be re-scaled and the resulting graph optionally dumped to the printer as many times as required. Examples of absorption and emission signals measured with the system are shown in Figs. 1 and 2. The size and print definition of the plot is determined by the Grappler interface, which is under software control. Once these functions are completed the computer waits for the next data acquisition trigger from the atomiser and overwrites the contents of the raw data buffer with the new data from the next measurement. Analytical Characteristics A major benefit of the use of wavelength modulation is that it contributes to an improvement in the signal to noise ratio obtained, in addition to providing background correction in both emission and absorption measurements.Detection limits achieved in the present study using tube wall atomisation were found to be similar to those previously reported using detection systems based on analog electronics.12J3 However, a computer controlled instrument offers advantages in terms of flexibility of operation, ease of use, and, more recently, cost. For example, it is possible to make use of computer control of modulation to select points not only for background correc- tion, but also for intensity measurement. It has been shown that calibration graphs can be extended by measurement of intensity in the wings of the atomic line profile, where there is still a linear response with respect to high analyte concentra- ( a ) .............. ....................CS ETA - AAS background signal from 1% NaCl at 283.3 nm ETA - AES background signal from 1% NaCl at 425.4 nm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fig. 2. Background correction using the wavelength modulation system. ( a ) , Continuum source ETA - AAS background signal for 1% sodium chloride at 283.3 nm (dotted line). The lower trace shows the signal after background correction; (b), ETA - AES background signal for 1% NaCl at 425.45 nm (dotted line). The lower trace shows the signal after background correctionANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 69 tions.15 In the present work, this has been achieved by the use of a 5-step square wave modulation waveform.16 Thus two overlapping calibration graphs can be produced, for low and high concentration measurements, which exhibit an over-all linear dynamic range of 4 to 5 orders of magnitude.The system also allows the simultaneous study of background and analyte signals, this being of considerable value in the investigation of interference effects. The scanning motor used has a positional feedback output, which allows direct observation of the intensity versus wavelength profile on an oscilloscope with n and y inputs. With absorption, this is possible only because the source has a continuum rather than a line character. This feature offers interesting possibilities in the diagnosis of spectral interferences17 Software for the system is still in a development phase. Currently, programs are available that allow the operation of the instrument with ektrothermal atomisers and flames.However, it is possible that the s z e type of background correction system could, in principle, be applied to ICP - OES. Such work is actively in progress in our laboratories. This work was made possible by the award of a grant from the SERC for the purchase of the echelle spectrometer. The authors are grateful to Perkin-Elmer Ltd. for the provision of the HGA 500 atomiser. Financial support from the Pye Foundation (for D. L.) and from SERC (for J. M.) is also gratefully acknowledged. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. References Slavin, W., Manning, D. C., and Carnrick, G. R., At. Spectrosc., 1981, 2, 137. Littlejohn, D., Cook, S., Durie, D., and Ottaway, J.M., Spectrochim. Acta, 1984,39B, 295. Rettberg, T. M., and Holcombe, J. A., Spectrochim. Acta, 1984, 39B, 249. Frech, W., and Jonsson, S., Spectrochim. Acta, 1982,37B, 1021. Slavin, W., and Manning, D. C,, Prog. Anal. At. Spectrosc., 1982, 5,243. Smith, S. B., and Hieftje, G. M., Appl. Spectrosc., 1983,37,419. Carnrick, G. R., Slavin, W., and Manning, D. C., Anal. Chem., 1981, 53, 1866. Keliher, P. N., and Wohlers, C. C., Anal. Chem., 1974,46,682. Zander, A , T., O’Haver, T. C., and Keliher, P. N., Anal. Chem., 1976,48, 1166. O’Haver, T. C., Analyst, 1984, 109,211. Harnly, J. M., O’Haver, T. C., Wolf, W. R., and Golden, B. M., Anal. Chem., 1979, 51,2007. Epstein, M. S., Rains, T. C., and O’Haver, T. C., Appl. Spectrosc., 1976,30, 324.Bezur, L., Marshall, J . , Ottaway, J . M., and Fakhrul-Aldeen, R . , Analyst, 1983, 108, 553. Marshall, J . , Littlejohn, D . , Ottaway, J . M., Harnly, J . M., Miller-Ihli, N. J . , and O’Haver, T. C., Analyst, 1983, 108, 178. Harnly, J. M., and O’Haver, T. C., Anal. Chem., 1981,53,1291. Miller-Ihli, N. J . , O’Haver, T. C., and Harnly, J. M., Anal. Chem., 1984,56, 176. Miller-Ihli, N. J . , O’Haver, T. C., and Harnly, J . M., Anal. Chem., 1982, 54, 799. ICP Source Utilisation and Sample Presentation R. D. Snook Department of Chemistry, Imperial College, London SW7 2AY The conventional ICP torch is constructed typically of three concentric tubes: the outer one is to contain the plasma and coolant gas; the middle tube provides a low flow of plasma support gas; and the axial tube acts as the injector tube with which to introduce an aerosol vapour or gas of the sample.The dimensions of these tubes are typically 19 mm i.d., 14 mm i.d. and 1.5mm i.d. The diameter of the injector tip (the latter dimension) is critical inasmuch as it must be sufficiently small to create a gas velocity of high enough pressure to puncture the plasma, so that the analyte will experience the high tempera- ture in the plasma rather than the cool outer environment. This type of torch is universally used in commercial instruments for no other reason than it is good enough and much of the theoretical work in plasma spectrochemistry has been done to describe this torch. Plasmas sustained in this type of torch are not homogeneous in temperature, axially or radially, and it is not surprising therefore that the emission intensity of the atom and ion lines of many elements show marked spatial dependencies.To compare these spatial positions in the plasma spectrochemists have defined a system of measuring the vertical position viewed by the spectrometer. Thus, we can say that the position viewed is 20, 30, etc. mm above the load coil, commonly abbreviated to a.1.c. Although this type of torch, which from now on I will call the conventional torch, is perfectly adequate for the purposes of spectrochemical analysis, it is costly to run, both in terms of initial outlay, to provide a high frequency generator capable of providing powers between 0.5 kW and 5 kW, and in terms of an argon consumption of about 16 1 min-1, consumed principally as coolant gas.Several attempts have been made to run torches at lower powers and lower gas consumptions. Some of these designs are radically different from the torch type shown here and I do not wish to discuss these. One type, however, constructed by Hieftje’ is a miniature version of this torch. Hieftje claims that there is no serious degradation of detection limits when using the miniature plasma, and noted the similarity of background features in the miniature plasma when compared with the conventional plasma. He further noted that the addition of easily ionisable elements changed the position of peak emission intensity for alkaline earth elements and presumed that this was due to a change in excitation temperature profile in the plasma.The interesting conclusion is the last one and we have, in our laboratory, measured the excitation and ionisation tempera- tures in a miniature torch of the Hieftje design. We have also determined the electron density at various viewing heights, and compared these values with the conventional torch to enable us to assess these changes in temperature. The torch design is similar to that of Hieftje and has tube dimensions of 12mm i.d., 9mm i.d. and 1.0mm i.d. for the coolant tube, plasma tube and injector tube, respectively. With this torch we can sustain a plasma at 600 W power and a total gas consumption of 6-8 1 min-1. We have verified Heiftje’s findings in respect of the detection limit’s linear range and background features. The major difference in these torches is, of course, the change in injector tip, which for a given injector flow-rate increases the axial velocity of the injector gas from 3.1 m s-1 to 9.4m s-1.The temperatures that we have measured are the excitation temperaure, T,,,, using the Bolzmann plot technique on three argon lines (430.01,426.63 and 425.94 nm) as recommended by Malone and Cocoran,* and the ionisation temperature by solving the Boltzmann - Saha equation3 for given intensity ratios of calcium ion/atom line ratios and cadmium ion/atom line ratios. Argon lines were chosen so that we could measure the electron density in the absence of a thermometric species. The argon lines used were chosen to be as close together as possible to avoid having to calibrate accurately the wavelength response of the spectromer and detector. The Boltzmann excitation temperatures obtained by Long70 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 and Snook4 for the large torch plasma and mini plasma are shown in Table 1.At lower power, 600 W, there is a significant drop in the temperature in the mini plasma when compared with the large plasma. To a lesser extent this is true at 1000 W. At high viewing heights the temperatures are much the same. We believe that the decrease in temperature for a given power at low viewing heights is due to the increased injector gas flow-rate, which cools the plasma, thus affecting the thermal Boltzmann temperature, and also decreases the residence time of the aerosol. Of course, these experiments only serve to show trends in temperature as we are assuming that the Boltzmann law holds for this source, which it probably does not, and that the argon lines are optically thin, i .e . , not self absorbed, which they probably are not. Tabie 1. Boltzmann excitation temperatures. All at injector gas flow-rate of 1.Olmin-1. Coolant gas flow-rate for large plasma of 13 1 min-1 and for mini plasma 8 1 min-1 Viewing T(1arge plasma)/K T(mini pIasma)/K height/mm I r a.1.c. 6OOW 1000 w 6OOW lo00 w 5 5600 5610 4843 5103 10 5450 5850 45 14 5196 15 5230 5980 4566 5573 20 4940 5370 4976 5070 The ionisation temperature is more difficult to obtain via the Saha equation as the ratio of ion to atom lines is required to solve the Saha equation and a knowledge of the electron density is required. We have therefore first calculated the electron density from stark half width measurements of the Hp 486.lnm line where the stark half width is proportional to the electron density via n, = C(n,, T)(Al~4)3/~ In order to obtain the stark half width we have first deconvoluted the calculated Doppler width from a neighbour- ing predominantly Doppler broadened line (Cu 465.11 nm), to determine the instrumental half width, and then deconvoluted this and the calculated Doppler half width for Hp from the experimental Hg profile.By using the compilations of C(ne, T ) we can therefore determine n,. The advantage of this method is that n, is independent of local thermodynamic equilibrium (LTE). We have thus measured the electron density over a wide range of powers for the conventional plasma. The predominant trend is for the electron density to decrease as the power decreases and as the viewing height increases, which would be expected.Overall, the electron density in the miniature plasma is higher than in the large plasma, e.g., at 10 mm in the mini plasma the rz, is 5 x 1021em-3 compared with 1.36 X 1021 e m-3 in the large plasma. The electron density at viewing heights below 15mm is higher in the presence of sample aerosol than in the dry plasma. In both instances the plasma is essentially dry at 25 mm and the electron density is the same. What does all this lead us to believe? Well, if the electron density is higher then probably the measured ionisation temperature is higher and the significance of that is that ion lines in the mini torch will be more intense than atom lines.In fact, both predictions turn out to be true. The Ti,,, temperature of both plasmas goes up with increased power and so does the ion to atom ratio, quite drastically with the mini plasma (Table 2). This feature has considerable implications because these ion lines in the plasma should be less sensitive to power and injector flow rate variations than atom lines. The second area of interest, which will develop over the next few years, is an improvement in over-all sample introduction efficiency, because using either the mini plasma or the conventional plasma the detection limits attainable are theoretically determined by the source noise in ICP - AES. Therefore, it may be that to obtain increased detection limits it will be necessary to change to electrothermal vaporisation or sample pre-concentration. Much attention has been paid to electrothermal vaporisation over the past 5 years, so I will not discuss it any further.A new interest is in using electrochemical preconcentration procedures in order to accumulate ultra-trace elements from solution at an electrode and subsequently to introduce them into the ICP as a more concentrated solution. Table 2. Ionisation temperatures. Conditions as Table 1, viewing height of 10 mm a.1.c. T (large plasma)/K T (mini plasma)/K Thermometric I . ? > species 6OOW 1000 w 600 w lo00 w - 6800 7250 7600 8500 5800 6600 7200 8140 CdII CdI CaII CaI - To achieve electrochemical pre-concentration we have been using the wall jet cell5 in its anodic stripping voltammetric mode to accumulate metals of interest from a low concentra- tion strong electrolyte solution (0.1 M potassium chloride solution) on to the electrode, by holding it at a suitable reduction potential for say 10 min and then applying an anodic potential to strip back rapidly the accumulated material into the small cell volume and then into the ICP.The essential features of the wall jet cell were the flow-rate dependency of the limiting current, the stripping current remaining the same over a wide range of flow-rates and the wide range of concentrations and deposition times for which the efficiency of the cell remained at 8%. Although this cell was adequate to demonstrate the principle of the technique the attainable pre-concentration was only a factor of three over 10min.An improvement was thought to be attainable by reducing the volume into which the analyte was stripped and thus the concentric slot electrode was conceived. The concentric slot electrodes has a probe which has a platinum annulus (Fig. 1). This is the working electrode and radially positioned from this are the counter and reference electrodes. A cup surrounds the probe and at its optimum position this cup is about 0.2 mm away from the probe. Thus, the solution volume (cup + outlet) is small, in fact 200 pl. The cell also operates under controlled hydrodynamic conditions and behaves as a tubular electrode, the volume flow-rate dependency of the limiting diffusion current being il 0~ V.33, between 1.0 and 10cm3min-1. We have studied this cell with cadmium and copper as the analytical species and have found that although we have reduced the cell volume from the wall jet’s 710 pl to 200 pl, the efficiency is almost the same as that of the wall jet cell because of the lower sensitivity of plating towards the solution flow-rate.Also the platinum electrode has a limited range at the pH values at which we wish to determine elements. Our latest development in this field is the reticulated vitreous carbon electrode (RVC).bThis cell is again a flow-through cell in which the working electrode is an RVC. The RVC has a pore size which varies between 20 pm and 100 ym and is fabricated by the pyrolysis of cross linked polymers; 97% of the volume is open space, so there is no resistance to solution flow. The electroactive area is estimated to be at least an order of magnitude greater than the other electrodes.The RVC is mounted in the centre of the cell and the reference and counter electrode are again placed radially to this working electrode (Fig. 1). The electrolyte solution can be pumped through the cell jet nozzle and through the nebuliser to the plasma, or to drain. Used in the anodic stripping voltammetric mode we can deposit elements on the electrode and subsequently strip them back into the small posteriorANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 71 Solution separation Imm I (b) Solution in c Count Reference electro electrode Waste RVC electrode t To ICP Fig. 1. ( a ) , Concentric cup cell; ( b ) RVCE cell 1 To ICP volume of the cell, pumping this now concentrated solution to the ICP for determination.The volume flow-rate dependence of the limiting current is il a vD.35 and the optimum pH for trace metals such as Cu2+ appears to be pH = 3.0, which differs from the wall jet cell (3.5-4.0). With the RVC electrode it is possible to achieve an improvement in detection limit of an order of magnitude after only 5 min plating. The plating efficiency of the RVC electrode is 35%, which stays constant over four orders of magnitude of concentration, thus matching the dynamic range of the ICP. While there is a slight advantage in using the wall jet and slot jet electrode, because they can be mechanically polished, the RVC electrode is the best cell for pre-concentration because of its high plating efficiency, which allows us to obtain pre- concentration factors of 10-100, depending on the time employed for plating. We envisage that its greatest application will be in seawater analysis. I would like to thank D. A. Ogaram and S. E. Long for their valuable assistance in obtaining the results described in this lecture. I would also like to thank the Laboratory of the Government Chemist for supporting this work. References 1. Savage, R. N., and Hieftje, G. M., Anal. Chem., 1980.52, 1267. 2. Malone, B. S., and Cocoran, W. H., J . Quant. Spectrosc. Radial. Transfer, 1966, 6, 443. 3. Boumans, P. W. J. M., “Theory of Spectrochemical Excitation,” Hilger and Watts, London, 1966. 4. Long, S. E., and Snook, R. D., Appl. Spectrosc., 1984, submitted for publication. 5. Long, S. E., and Snook, R. D., Analyst, 1983, 108, 1331. 6. Ogaram, D. A., and Snook, R. D., Analyst, 1984, 109, 1597. Environmental Chemistry Vol. 3 Senior Reporter H. J. M. Bowen A review of the literature published UP to the end of 1982. Disposal and Utilization of Sewage Sludge Possible Consequences of Sewage Sludge Disposal and Utilization and the Need for Monitoring Brief Contents: Tropospheric Ozone Ozone Sources in the Unpolluted Troposphere Photochemistry of the Clean Troposphere Ozone Distribution in the Troposphere Sinks of Ozone in the Unpolluted Troposphere Tropos heric Ozone Budget Ozone Formation and Destruction in Polluted Air Elevated Ozone Levels Biological Effects of Ozone Analytical Techniques The Environmental Chemistry of Organotin Compounds Toxicological Patterns of Organotins Analysis of Organotins at Environmental Levels Modes of Entry into the Environment Aqueous Chemistry Transformations in the Environment Degradation of Organotin Compounds Determination of Heavy Metals in Sewage Sludge Analysis of Sewage Slud e Selected Procedures for lludge Analysis Inorganic Deposits in Invertebrate Tissues Metal Deposits Li and Binding Sifca Deposition Urates Specialist Periodical Report ( 1984) Hardcover 153pp 0 851 86 775 8 Price f41.00 ($74.00) RSC Members f27.00 RSC Members should send their orders to: The Royal Society of Chemistry, Membership Officer, 30 Russell Square, London WClB 5DT. Non-RSC Members should send their orders to: The Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 1 HN, England. The Royal Society of Chemistry Burlington House Piccadilly London W l V OBN

ISSN:0144-557X    

DOI:10.1039/AP9852200063

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年代:1985

数据来源: RSC

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72 ANALYTICAL PROCEEDINGS. MARCH 1985, VOL 22 The Application of Analytical Chemistry in Archaeology The following are summaries of five of the papers presented at a Meeting of the South East and Western Regions and the Microchemical Methods Group held on September 10th-1 Ith, 1984, in The Polytechnic, Portsmouth. X-ray Fluorescence Analysis of Non-ferrous Archaeological Metalwork Part 1. Analytical Technique E. E. H. Pitt Department of Applied Physical Sciences, Coventry (Lanchester) Polytechnic, Priory Street, Coventry CVI 5FB The basic theory and instrumentation required in wavelength dispersive X-ray fluorescence spectrometry have been des- cribed elsewhere. The sampling of “museum objects,” which are often unique pieces and of very high value, presents three major problems.Firstly, how representative of the bulk material is the sample taken? In general, the larger the object the greater is the change of heterogeneity being introduced during the manufacture of the object. This is particularly true when complex alloys such as leaded bronze are involved. Secondly, the presence of surface patina, which often differs in composition from the bulk material. While the composition of this surface layer may be of interest it is usually the analysis of the bulk material that is required. Thirdly, sampling must do minimum damage to the object being analysed. This is often the limiting factor; while multiple sampling is desirable this is quite often unacceptable to museum curators. Two methods of sampling have been used. First, the taking of filings.This method has the advantage of presenting a larger effective volume per unit mass to the primary X-ray source, but has the disadvantage of damaging a larger surface area. More care has also to be taken to make sure that all surface patina has been removed before the sample used in analysis is taken. Secondly, the taking of drillings. This method is favoured by most museum curators as only the minimum of damage is done to the sample. A 1-mm drill is used; the drillings are discarded until bright metal is observed, when approximately 10-mg samples are removed. This usually leaves a hole 1-2 mm deep. The sample is placed on 6 pm Mylar, spread carefully with a small brush to maximise surface area in the X-ray beam and then sealed under Scotch 810 adhesive tape. The Mylar with the sealed sample is then stretched tightly between two thin cardboard rings (external diameter 50 mm, which is the internal diameter of the sample cup used, internal diameter 35mm) which are then stapled together, the excess Mylar being cut off.The “810” tape was selected as this gave the lowest blank value for the elements being measured. This method of sample preparation has the advantage of maximising the sample volume “seen” by the primary X-rays. Also, the sample can be labelled on the card rings, thus minimising any chance of sample “mix-up,” the method gives a relatively low storage volume for a large “library” of samples, and the samples are available for further study and can be sent “through the post” to other laboratories without the need for extensive packaging.The elements measured quantitatively are Sb, Sn, Ag, Pb, As, Zn, Cu, Ni and Fe in brasses and bronzes, and Sb, Sn, Pb, Zn, Cu and Fe in pewter. With bronzes, two line-overlap problems are observed, ASK, - PbL, and SnK, (2nd order) - PbLp. Provided that the tin is in the normal range expected in bronzes it is possible to remove SnK, (2) with PHA (lower level 300 window 400), thus enabling the PbL, line to be used to measure Pb. It is not possible, by using pulse height analysis (PHA), to separate ASK, from PbL,, hence the weaker ASK, line has to be used for the determination of As, the counting time being increased to 100s. With pewters it is not possible, owing to the very high Sn content, to remove SnK, (2) from PbLp. Hence, the PbL, has to be used to measure Pb.This is usually satisfactory as the As level in pewter is normally very low. Should a pewter be found that contains a high level of As then a correction of the PbL, line for ASK, has to be used, the ASK, value being obtained by using ASK@ and the ratio One major problem is the provision of meaningful stan- dards. None of the alloy standards commercially available ASK, ASK,. Table 1. Analysis of standards against drilled subsample “a” of standard 1 Composition of standard 1, % m/m Composition of standard 2, % m/m Actual* Element value Sb 2.09 Sn 87.7 Bi 1.95 Pb 5.36 Zn 0.82 c u 2.00 Subsamp. “b” drilled 2.09 88.4 1.76 4.89 0.86 1.93 Subsamp. “c” drilled 2.15 87.1 1.96 5.85 0.88 1.93 Filed subsamp. 1.84 80.1 3.29 9.15 1.41 3.59 Actual* value 1.10 80.7 0.95 15.55 0.44 0.99 Subsamp.“a” drilled 1.10 81 .O 0.81 15.53 0.49 1.09 Subsamp. “b” drilled 1.08 79.5 0.91 16.84 0.51 1.13 Filed subsamp. 0.93 71.3 1.36 23.2 0.66 1.61 * Determined by independent consultant analyst.ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 73 today has the composition found in many museum objects. It is, however, possible to analyse bronzes by using a combination of two of the standards available. The standards used for pewter were “tailor made” for the alloy compositions expected and analysed by an independent consultant analyst. It is critical that the physical form of the standards should be the same as that for samples, i.e., used drilled standards for drilled samples, filed standards for filed samples.Table 1 shows the effect of sample “form” in the analysis of pewter. Bronzes show a similar but smaller effect. The analytical regime devised is now illustrated by consider- ing the analysis of pewter. Brass and bronze are analysed using a similar type of regime. Pewter Analysis The sample is first analysed qualitatively, using the most advantageous spectrometer conditions for each part of the X-ray spectrum, for all elements having atomic numbers above 21. A background “trace” has also been recorded and a tracing made of this on transparent acetate sheet. The positions of all of the spectral lines of the elements expected are marked on this “trace.” The edited background trace is then superimposed on the analytical trace, thus making it possible to evaluate without reference to 20 tables which elements are present.The peak heights of SnK,, PbL, and CuK, are measured for all samples, together with the peak heights given by a standard containing 80.7% Sn, 15.5% Pb and 1.0% Cu. The approxi- mate composition is then calculated from these peak heights. A normalisation calculation is used to account for different sample masses, the sum of the elements measured being taken as 99.5%. This preliminary calculation indicates if the pewter is “fine metal” or “lay metal.” Fine metal was defined by the Pewterers Company in the 14th Century as an alloy containing up to 26 lb of copper per 112 Ib of tin, while lay metal contains up to 261b of lead per 1121b of tin. The values also give a double check on the final quantitative analysis, thus making certain that the data has been correctly “fed” into the computer.Table 2. Analysis of sample 4B Determination number 1 2 3 4 5 1 U Sb 0.06 0.04 0.01 0.09 0.04 0.05 0.03 Composition, % mlm Sn Bi Pb Cu Fe 96.07 0.74 0.60 2.45 0.11 95.84 0.77 0.66 2.56 0.13 96.18 0.76 0.60 2.39 0.11 95.96 0.80 0.60 2.44 0.13 96.00 0.77 0.63 2.53 0.05 96.02 0.77 0.62 2.47 0.11 0.11 0.02 0.03 0.07 0.03 Table 3. Analysis of eight sub-samples from a pewter spoon handle Composition, YO mlm Sb 1B 0.04 2B 0.05 3B 0.0 4B 0.05 1T 0.0 2T 0.03 3T 0.07 4T 0.04 f 0.04 U 0.03 * Excluding 3T. Sn 95.95 97.12 96.55 96.02 96.60 96.89 96.55 97.00 96.89 0.43 Bi Pb Cu Fe 0.80 0.57 2.64 0.01 0.57 0.50 1.73 0.07 0.60 0.64 2.12 0.12 0.77 0.62 2.47 0.11 0.61 0.68 2.06 0.07 0.65 0.55 1.84 0.07 0.57 0.48 1.67 0.68* 0.56 0.53 1.83 0.04 0.64 0.57 2.05 0.15 0.09 0.07 0.35 0.22 x 0.07 0 0.04 The sample is then analysed quantitatively by measuring the X-ray intensity at the relevant 28 values for the element lines and their associated backgrounds, the 20 values and relevant counting times being permanently stored in a programmer which is linked to the X-ray spectrometer. A blank, consisting of Scotch 810 tape stuck on to Mylar, and the relevant standard are analysed twice with each batch of samples, once at the start of a batch and then again near the end of a batch.The average values of these measurements are then used in the subsequent calculation of quantitative data. This calculation is undertaken on a microcomputer, the variation of sample size being overcome by use of a normalisation calculation.A Mediaeval pewter spoon was obtained and the handle sampled in 8 places, 4 samples on the top of the handle (lT-4T), 4 from the bottom (1B-4B). One sample (4B) was selected at random and analysed five times, at intermittent intervals during the analysis of the batch of the 8 samples, while each of the other samples was analysed once. The results are given in Table 2 and 3. The results of Sn, Bi, Pb and Cu show that the precision of the method is several times greater than the variation in composition. With Sb and Fe it is of about the same order of magnitude when sample 3T, which on close examination was seen to contain corrosion products, is discarded. Both of these elements are, however, only present at a low concentration.The results indicate that provided care is taken, particularly with heavily corroded objects, with sampling, the accuracy of the method used is sufficient when the constraint of sample heterogeneity is taken into account. If, as is usually the case, only a single sample is permitted, then the results obtained are usually sufficiently accurate to satisfy “archaeological require- ments.”. X-ray Fluorescence Analysis of Non-ferrous Archaeological Metalwork Part 2. Archaeological Applications R. Brownsword Department of Applied Physical Sciences, Coventry Polytechnic, Priory Street, Coventry CV1 5FB Consideration is given to the contribution which analytical surveys of relatively large numbers of objects have made to a number of issues of interest to the archaeologist. These discussions are illustrated by reference to examples from analytical work on copper-alloy and pewter objects, mainly from the Mediaeval period. Establishing Basic Alloy Type The purpose of this type of work is to put alloy description on a better footing.Terms such as “bronze” and “bell-metal” have been widely used in archaeological reports and articles without analytical support, although more recently “copper-alloy” has been substituted. Designation presents no analytical difficul- ties, the main problem being one of terminology with copper alloys. Fig. 1 is a useful means of presenting alloy composi- tional data and some of the terms used are indicated. It is evident from our work that the alloy used in making skillets and mortars was not “bell-metal” but a heavily leaded bronze,l and spurs and purse-frames, commonly referred to as made of “bronze,” are in fact made of latten.74 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 Pb rich Latten Zn rich Sn rich Fig.1. A scatter diagram for displaying large numbers of alloy compositions of copper alloy in respect of the three main elemental additions zinc, lead and tin. Some alloy terms are indicated Detection of Repairs, “Marriages” and Reproductions Repairs can usually be confirmed because they have a significantly different alloy composition from the original. In a similar way “marriages,” the occurrence together of parts not originally put together, can be detected. These may not always be innocent attempts to retrieve the situation of a broken object by “cannibalising” a similar object.It is important that “marriages” should be recognised as such, otherwise efforts at classification and stylistic analysis can be thwarted. Reproduc- tions of early objects can be more difficult to detect as they have no internal reference material. However, by comparison with data from a number of similar objects and by taking other indications into account it is often possible to identify reproductions. Aid to Object Classification and Stylistic Analysis A confused picture can sometimes be clarified when alloy compositional data on a population becomes available. Classi- fication of 13th century steelyard weights on stylistic grounds had been attempted previously with limited success; a more comprehensive survey of alloy compositions has allowed a more satisfactory classification to be produced.2 Mediaeval pewter is rarely found in good condition and flatware (plates, etc.) classification has not previously been attempted.However, a correlation between an angled-bead rim reinforcement and a high copper content for what are believed to be early mediaeval items might form a basis for flatware classification because pewter flatware of the late mediaeval period has a rounded bead and a lower copper content. Information on Technology of the Period The additions used to harden pewter were left to the pewterer, subject only to a density constraint to curb excessive additions of lead. Copper, bismuth and antimony are mentioned in historical sources but the amounts to be used are not clearly stated.Analysis has shown that copper was the main hardening addition, with occasional high levels, whereas bismuth and antimony were rarely above trace level in mediaeval pewter flatware3 and spoons. An interesting example has been found4 of the use of mercury to harden a pewter spoon, as described by Theophilus. Analysis of a later plate by Taudin (~1700) has shown that small antimony additions may have been responsible, at least in part, for the success of this pewterer in selling his “Hard Metal. ’’ In respect of copper alloys, no attempt has been made to seek detailed correlations between impurities and ore-bodies, as has been carried out in the past, because of the attendant risks. However, the general ore-type can often be deduced from analysis of the alloy.For example, high antimony and arsenic levels are suggestive of afahlerz-type ore, rich in these elements, and high nickel levels are thought to indicate the use of a kupfershiefe-type ore from the Mansfeld area. Analytical data on the main elements copper, zinc, tin and lead indicate the broad approach used in alloy selection. For example, it is clear that highly leaded bronzes were widely used to cast cooking vessels; the alloy was relatively cheap and easy to cast in the thin-walled form required. The use of this alloy was extended to mortars and weights, objects required to be massive and subject to modest stresses. These essentially zinc-free alloys were not used where colour was important; latten, containing zinc, was then used. Cast latten often contains significant lead (whether added deliberately or not is not clear at present) but lead levels are low in objects that have been gilt and in wrought objects.In the Mediaeval period zinc was introduced into copper to produce latten or brass by a cementation process, using finely divided copper and calamine. The efficiency of this process increased with time and it has been shown5 for memorial “brasses” that the zinc content increases with time. It was hoped that simulated cementation experiments would establish a maximum achievable zinc content as an aid to the detection of fakes or reproductions but there are some associated problems. From the 16th century onwards (and perhaps also during the mediaeval period) it became possible to produce brass by the modern method of adding zinc metal brought from Asia to molten copper and so achieve higher zinc levels.It may prove possible to trace the presence of unusually high levels of lead (and perhaps other elements) to the source of calamine used in the cementation process. However, from the 16th century, the use of furnace calamine from the Harz area must be taken into account. Provenancing and Dating Objects There are indications that alloy analysis may be successful in these respects for cast copper-alloy objects from north-west Europe from the Mediaeval and immediately Postmediaeval periods. There is no direct dating technique for such materials comparable with the 14C or TL methods. However in broad terms it appears to be possible to suggest provenance and date for some groups of objects.Past efforts at linking object alloy composition and ore- bodies have been less than fully satisfactory, due in major part to the probable use of scrap. This leads to the blurring of possible links. In the Mediaeval period, however, it is believed that this presents a much less serious problem, as the massive expansion in output of newly extracted metal would ensure that the vast majority of objects would have been made without the use of scrap (apart from “in-house” scrap). The present approach in any case concentrates on the levels of the major elements zinc, tin and lead in the copper alloys. The development of this approach stemmed from an early realisation that objects, believed from their style to have been made in broadly the same area at broadly the same time, had roughly similar alloy compositions.6 This led to the concept of an alloy compositional profile, which differed with time and place.The underlying causes of these differences are essen- tially those of local availability and cost of the metals concerned. A particular benefit to the archaeologist of alloy compositional comparisons is the facility to compare objects of very different form but likely to have been made by the same craftsmen using the same materials and technique. Thus, for example, candlesticks can be compared compositionally with chafing dishes and lavers.6ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 75 It is recognised that the results of such data comparisons do not constitute proof of any date or provenance, but because the information is additional to any stylistic or other information, the contribution can be important.1. 2. 4. 5 . 6. In conclusion, it must be said that the degree of certainty associated with comments derived from alloy analysis de- information must be treated accordingly. However, as work proceeds the levels of confidence will almost certainly increase. creases through the sequence of the foregoing sections and the References Brownsword, R., Med. Arch., 1982, XXVI, 164. Brownsword, R., and Pitt, E. E. H., Proc. Dorset Nat. Hist. and Arch. SOC., 1983, 105, 83. Brownsword, R., and Pitt, E. E. H., Archaeometry, 1984, 26, 237. Brownsword, R., and Pitt, E. E. H.,J. Hist. Met. Soc., 1983,17, 119. Cameron, H. K., Arch. J . , 1974, 131, 215. Brownsword, R., and Pitt, E.E. H.,J. Hist. Met. SOC., 1983,17, 44. Archaeological Applications of Atomic-absorption Spectrometry M. J. Hughes British Museum, Research Laboratory, Great Russell Street, London WC I B 3DG Introduction Atomic absorption is a widely-used analytical technique with features of particular value for analysing archaeological objects. The British Museum Research Laboratory has used AAS for a number of years and made several thousands of elemental analyses; other laboratories also use AAS for archaeological materials. Its applications can be broadly divided into two categories, namely metals and silicates. Among ancient metals the major amount of work has been on copper alloys but other studies have been on gold, silver, lead and tin and their alloys, and on iron.Analysis of silicate-based materials has included ancient pottery, rocks and minerals, glass, enamels and refractories for metalworking. Analytical Technique For most applications, the flame mode provides sufficient sensitivity but occasionally electrothermal atomisation is necessary where the elements selected are in low concentra- tions. In order to analyse solid objects it is necessary to remove some of the object in a sample form, weigh the sample and dissolve it, usually with acids. The techniques used at the British Museum have been described elsewhere.' For copper- alloy objects we normally analyse drillings (20-30 mg) taken with a 1 mm steel twist-drill. After weighing out about 15 mg, dissolving in aqua regia and diluting to 20m1, the solution obtained is suitable for the analysis of 13 elements (Cu, Pb, Sn, Zn, Ag, Fe, Sb, As, Bi, Ni, Co, Cd, Au) in batches of 50-150 samples at a time.For sampling ceramics or glass various drills can be used, such as synthetic sapphire, tungsten carbide or diamond- embedded drills (the latter especially for glass or enamels). Dissolution of silicates is carried out either using hydrofluoric acid - perchloric acid or a lithium metaborate fusion (Si can be measured). On the general question of accuracy, for major elements in copper alloys and silicates with 10-20 mg samples the coefficient of variation on repeated analysis is about 1-3%, for minor elements 5-10% and for trace elements it can be 520%. Metals Copper alloys are numerically the largest group; among the many programmes of bronze analysis293 we have recently been looking at the composition of Early Bronze Age (EBA) axes in southern Britain with regard to changes in alloy types with time and changes in minor elements, especially as they may relate to the use of different metal sources.This work has shown that very low tin and high arsenic (46% As) percentages occur in the earliest part of the EBA, followed by a rapid increase in tin and fall in arsenic percentage, the tin stabilised at about 10-1lo/~ of tin by mass in the copper alloy. One may note in passing that for such projects one needs to undertake analyses of largish numbers of objects in order to see a pattern emerging and for this AAS is well suited. One may use the analyses of copper alloys in different ways, the most useful we believe to be that of revealing aspects of ancient technology, viz., how objects were made and the types of alloys being used at different chronological periods. Other metals present greater analytical difficulties; for gold alloys, the main elements are gold, silver and copper, and high acid concentrations can usually keep all three in solution simultaneously.Some Bronze Age gold torcs (neck rings) from Ipswich were analysed by AAS4 and contained between 11 and 28% of silver and 0.3-12% of copper, both metals (except copper below about 1 Yo) probably representing deliberate additions to the gold. For silver aIloys, most elements including silver can be analysed with a sample dissolved in dilute nitric acid. Gold and tin (the exceptions) can then be measured with a further sample dissolved in aqua regia (silver precipitated).In recent years analyses of silver and gold objects at this Laboratory have mostly been by X-ray fluorescence.5 Silicates The major use of AAS for ceramics has been provenance studies, i.e., indicating the source of the pottery by matching its analysis with a chemical profile of pottery samples taken from a number of known possible sources of manufacture. We have used AAS in a relatively limited way for the provenance of ceramics, having in recent years introduced instrumental neutron activation analysis6 because of the larger numbers of elements that it is possible to measure in a single sample. One project involving the use of AAS has been on Anglo-Saxon pottery7; the question arose as to whether Anglo-Saxon pots found in Kent were local Kentish products or were imported from the Continent. By analysing pots found definitely associated with Kent and Continental kilns the pottery from these kilns was characterised.The analyses of pots found in Kent but of unknown origin could then be matched against t ose characteristics using appropriate statis- tical techniques a 7-l d many were shown to be Continental imports. In order to digest the mass of elemental data, multivariate statistical techniques need to be used, e.g., discriminant analysis8 and cluster analysis.9 Other laboratories have been engaged in the analysis of ancient ceramics by AAS.10-12 Other silicate materials which can be usefully analysed include materials associated with ancient metalworking such as crucibles, furnace linings and slags; the analyses can shed light on the processing techniques.13 Rocks and minerals present a further application for AAS; a recent large project at the Laboratory,l4 now being continued at Imperial College using ICP spectrometry, has been the analysis of Neolithic and Bronze Age flint axeheads as a means of determining how far the flint was distributed from the flint mines.Finally, glass and enamels can be analysed for major and76 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 trace elements in order to give information on the type of raw materials that have been used, on whether a glass formula was being adopted and on the metals used to colour glasses. Future Developments One of the recent developments in atomic spectroscopy which has received much attention is inductively coupled plasma arc spectrometry (ICP) .This technique has similar applications to AAS for archaeological materials. 15-16 The linking of an ICP source to a mass spectrometer17 allows additional scope for measuring isotope ratios. In archaeology, there has been some research, especially on the use of lead isotope ratios,lg which have indicated the source of the lead ores used to make an object. Conclusion The range of archaeological materials that can be analysed by AAS is quite wide and it should be possible for many individuals or groups to collaborate with archaeologists and undertake research using AAS on suitable groups of material. References 1. Hughes, M. J., Cowell, M.R., and Craddock, P. T. C., Archaeometry, 1976, 18, 19. 2. Craddock, P. T. C., J . Archaeol. Sci., 1976, 3, 93. 3. Craddock, P. T. C., in Oddy, W. A,, and Zwalf, W., Editors, “Aspects of Tibetan Metallurgy,” British Museum Occasional Paper 15, British Museum, London, 1981, pp. 1-37. 4. Brailsford, J., and Stapley, J. E., Proc. Prehistoric SOC., 1972, 38, 219. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Hughes, M. J., and Hall, J. A., J. Archaeol. Sci., 1979,6,321. Hughes, M. J., Cherry, J., Freestone, I. C., and Leese, M. N., in Freestone, I. C., Johns, C., and Potter, T., Editors, “Current Research in Ceramics: Thin Section Studies,” British Museum Occasional Paper 32, British Museum, London, 1982, Cowell, M. R., (Appendix 3) in Evison, V. I., “A Corpus of Wheel-thrown Pottery in Anglo-Saxon Graves,” Royal Archaeological Institute, London, 1979, pp.96-99. Hope, K., “Methods of Multivariate Analysis,” University of London Press, London, 1968. Wishart, D., “CLUSTAN User Manual, Version 1C release 2,” Program Library Unit, University of Edinburgh, 1978. Hatcher, H., Hedges, R. E. M., Pollard, A. M., and Kenrick, P. M., Archaeometry, 1980,22, 133. Tubb, A., Parker, A. J., and Nickless, G., Archaeometry, 1980, 22, 153. Megaw, A. H. S., and Jones, R. E., Annu. Br. Sch. Archaeol. Athens, 1983, 78, 235. Tite, M. S., Maniatis, Y., Meeks, N. D., Bimson, M., and Hughes, M. J., in Wertime, T. A., and Wertime, S. F., Editors, “Early Pyrotechnology ,” Smithsonian Institution Press, Wash- ington, 1982, pp. 61-71. Craddock, P. T., Cowell, R.M., Leese, M. N., and Hughes, M. J., Archaeometry, 1983, 25, 135. Hart, F. A., and Adams, S. J., Archaeometry, 1983, 25, 179. Maggetti, M., Westley, H., and O h , J. S., in Lambert, J. B., Editor, “Archeological Chemistry 111,” Advances in Chemistry Series, Vol. 205, American Chemical Society, Washington, Gray, A. L., and Date, A. L., Analyst, 1983, 108, 1033. Gale, N. H., and Stos-Gale, Z. A., Sci. Am., 1981, 224, 176. pp. 113-122. 1984, pp. 151-191. The Fate of Buried Fats and Oils and the Remains from a 1000-year-old Eskimo Dwelling E. D. Morgan Department of Chemistry, University of Keele, Staffordshire L. Titus Department of Archaeolog y, Simon Fraser University, Burnab y, BC, Canada If one excepts the inorganic portions, all living material consists essentially of protein, carbohydrate and fats (or lipids), and although these substances are all fragile, particularly in an archaeological sense, under the right circumstances they can survive immersion or burial for hundreds or thousands of years.Hence, materials made from protein and carbohydrate, such as leather, skin, horn, paper, wood and linen, if they survive, are all prized for the information that they give to the archaeologist. We may describe this information as structural information. Lipids are the Cinderella of this trio, and remain largely neglected as a source of archaeological information. However, it is noteworthy that the breakdown products of protein and carbohydrate are water soluble, while the decom- position products of lipids are water insoluble, and although a mass of fat or oil may have no structural information, there can be information at the molecular level.The present state of usefulness of lipid analysis to provide archaeologically useful information is illustrated through accounts of our first study in the area and two recent investigations with a marine connection, which are appropriate to the Microchemical Methods Group’s meeting at Portsmouth and the current interest in recoveries from the “Mary Rose” and the “Invincible.” Bog Butter One of us was introduced to the subject or archaeological lipids through the challenge of analysing, by modern chromato- graphic methods, samples of “bog butter,” which are lumps of greyish-white waxy material found from time to time during peat cutting in bogs in Scotland and Ireland.There are literature references that suggest that in Mediaeval and later times, people buried butter in peat to preserve it for later use and indeed that such material was prized for cooking.1 Titration, thin-layer chromatography for lipid classes and gas chromatography of the fatty acid methyl esters showed that the “bog butter” as found was certainly not butter, but consisted almost entirely of free fatty acids with a large proportion of palmitic acid (C16 : 0) and practically no oleic acid (C18 : l), with a general tendency towards shorter chains and saturated acids than is found in triglyceride fats and oils. The material closely resembled adipocere, the fatty, waxy remains long known from human burials in wet soil, or where human remains are left immersed in water.2.3 Experimentally, it has been shown that a number of lipids of different origin, if incubated with anaerobic micro-organisms in water, are converted to the free fatty acids of adip0cere.3.~ Eskimo Midden Investigation of a driftwood and turf structure, which was being rapidly eroded by wave action, on the shore of Herschel Island in the Canadian Arctic showed that it was the remains of a Thule Eskimo dwelling, radiocarbon dated to approximately 1000 years BP.5 Just outside the entrance to the dwelling, and lying just below the low water mark, was a large brown - black mass of degraded fatty material, mixed with sand, silt and gravel and from the animal bone remains and bone artefacts, aANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 77 fragment of pottery, a stone knife and other implements, it was identified as the refuse tip of the inhabitants.It was recovered intact as a solid mass of approximately 500 kg. Analysis of representative samples showed a high content of hexane-extractable lipid which consisted chiefly of free fatty acids.6 There was no sign of the highly unsaturated acids represented by C20 : 5 , (22 : 5 and C22 : 6, which are charac- teristic of marine animals fats. These unstable acids could be expected to have polymerized quickly. However, the extract contained large amounts of mono-unsaturated acids, i.e., conversion to adipocere had taken place only partially, presumably because of the cold climate or an unsuitable environment for microbial growth. The presence of unsatu- rated acids up to C22 : 1 suggested the presence of marine oils.However, because of the lack of distinct species differences in the fatty acid composition of whale, seal and walrus blubber and the variations with individual, season, sexual maturity and part of the animal from which the blubber is taken, it is not possible to make any conclusions about the species which formed the major part of the diet of these Eskimos.7 The bones found preserved in the midden heap are a better guide to diet. More important is the startling fact that fatty material can remain partially unchanged over such a long time in a cold environment. Minor polar and non-polar lipid fractions, separated by TLC, and not found earlier in land animal adipocere remain to be investigated.With further work, it may be possible to tell more about the origin of archaeological adipocere from such minor constituents still present in it. Basque Whaler A brief account was also given of analysis of material from the wreck of a 16th century Basque whaler at Red Bay in Newfoundland Labrador. The sunken wreck was found in shallow water a short distance from the remains of a shore whaling station.8 The ship is concluded to be the “San Juan,” which, loaded with whale oil ready to be shipped to Spain, was wrecked in 1565. The staves of collapsed barrels were still in the hold and black ooze, collected from the bottom of the ship, was shown on analysis to contain significant amounts of extractable fat. The free fatty acids found indicated an original composition comparable to the Eskimo midden material, but conversion to adipocere had proceeded further, probably because of the higher water temperature than at Herschel Island.However, there was still some evidence of the probable marine mammal origin of the original lipid. It is hoped that as data accumulates and techniques improve, that it will be possible to extrapolate more accurately from present to original composition of lipids and to deduce more accurately the lipid source of other archaeological samples. If care is taken to avoid contamination, the methods can be used with quite small (mg) samples. Archaeologists are exhorted not to ignore the potential for information from lowly lumps of grease or fat or unpromising black ooze. The authors thank R.J. Small and Corony Edwards, students at Keele, who carried out many of the analyses, and Professor J. A. Tuck of Memorial University, NFLD, and M. Richard Grenier of Parks, Canada, for their help in providing samples from Red Bay. 1. 2. 3. 4. 5. 6. 7. 8. References Thornton, M. D., Morgan, E. D., and Celoria, F., Sci. Archaeol., 1970, Nos. 2 & 3,20. Mant, A. K., J. Forensic Med., 1957, 4, 18. den Dooren de Jong, L. E., Antonie van Leeuwenhoek; J . Microbiol. Serol, 1961, 27, 337. Morgan, E. D., Cornford, C., Pollock, D. R. J., and Isaacson, P., Sci. Archaeof., 1972, No. 10, 9. Yorga, B., “Washout: A Western Thule Site on Herschel Island,” Mercury Series No. 98, National Museums of Canada, Ottawa, 1980. Morgan, E. D., Titus, L., Small, R. J., and Edwards, C., Arctic, 1983,36,356.Morgan, E. D., Titus, L., Small, R. J., and Edwards, C., Archaeometry, 1984, 26, 43. Tuck, J. A., and Grenier, R., Sci. Am., 1981,245, 126. The Role of Analysis in the Conservation of Antiquities V. Daniels Conservation Division, Department of Scientific Research and Conservation, British Museum, London WC7B 3DG The British Museum’s collection of antiquities is made of a very wide range of materials varying widely in their stability: from very stable flint and gold to comparatively unstable animal skins and vegetable remains. The rate of deterioration of all materials is greater than zero and the aim of conservation is to decrease this rate and to clean and repair previously dirty or broken items. Most of the analysis performed to aid conserva- tion in the British Museum is carried out by its team of conservation research scientists.They study the mechanisms of deterioration of antiquities, investigate new methods and materials for the conservation and display of antiquities, investigate problems that occur during conservation or storage and perform analysis where this is necessary for conservation purposes. One important mechanism for the deterioration of porous ceramics and stone is the crystallisation of hygroscopic salts below the surface of objects. Such salts enter objects from ground water by rising damp or diffusion during burial. Their continued presence in objects after excavation can cause spalling of the surface or eventual total destruction of the object . I If a limestone contains large amounts of water absorbing clays it may not be safe to soak the stone to remove the soluble salts.Analytical results for acid insoluble residue can be related to the stone’s suitability for washing.2 The washing process can easily be followed because most salts contain chloride and this is easily detected by using the silver nitrate test. Stones unsuitable for washing by immersion in water can still be cleaned using damp poultices of hydrated magnesium silicate. Silver objects can tarnish in storage owing to the evolution of sulphur containing volatiles from nearby materials, such as wool, sulphur dyes, rubbers, etc. ; previously, an accelerated ageing test had been used to detect these, but recently a microchemical method based on one of Feigl’s spot tests has been developed.3 The new test is based on the rate of evolution of nitrogen bubbles caused by materials immersed in a solution containing sodium azide.The test gives excellent agreement with the accelerated ageing test. The only exception being stable sulphides, which give a positive azide test but do not tarnish silver. However, this is not a problem with the types of materials tested for use in storage and display areas. The test is also useful for testing materials intended to be in close proximity to photographs, as the silver containing black and white image is also attacked by hydrogen sulphide, resulting in fading. Photographs can also be endangered by poly(viny1 chloride) (PVC) storage envelopes. On several occasions small spots of liquid have been seen between film and the PVC sheeting.78 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 Infrared analysis of this liquid showed that it was a phthalte, a family of compounds often used for the plasticisation of PVC.Objects made of synthetic polymers are increasingly becoming a problem for conservation. Over the last century many scientific instruments and everyday objects were made of nitrocellulose. It was almost always plasticised by use of camphor, but this disappears by volatilisation, causing shrink- age and embrittlement. Additionally, the nitrocellulose itself becomes yellow and evolves nitrogen oxides during degrada- tion, becoming powdery and brittle. There are some Turkish- style shadow puppets in the Museum’s ethnographic collection which showed severe signs of decay.The steel pins by which the legs were attached to the body had completely corroded and the recently replaced linen tapes which held the puppet to the storage tray had rotted away and had a pH of 1.5. Part of one of the legs was severely cracked and yellowed. Infrared spectro- scopy was able to confirm the nature of the problem, and some changes in storage were recommended to prolong the life of rhe nitrocellulose objects, which had caused all of the symptoms above. An unusual example of deterioration was found in a group of three Chinese figures (Fig. l ) . 4 It was evident that the initially red surfaces had become yellow and in the further stages of deterioration had started to become powdery. X-ray diffrac- tion, X-ray fluorescence and infrared analysis showed that the figures were made principally of the red mineral realgar, A s ~ S ~ .It is known that realgar photoxidises to form yellow orpiment and arsenic oxide (As203). The latter is easily absorbed into the body and is thus very toxic. The statues represent the Daoist star gods longevity, happiness and rank. It is thought that the owners of these objects would have used them to ingest small quantities of arsenic with what they hoped would be beneficial effects. The central statue is carved from solid realgar, but those on the left and right show a different construction. Slabs of initially red realgar were set into a red mixture of vermilion (HgS) and resin. The slabs are now yellow but the resin mixture is still red. Not all conservation problems arise from the natural deterioration of objects. Many objects have been treated before, perhaps in antiquity, but more often in one of what could be several separate conservation processes. In the past, conservation has not always been up to the high standard of modern techniques, and odd things can happen to objects. One print was being cleaned in an oxidising bleach solution when it became brown all over. The problem was investigated and X-ray fluorecence analysis showed that the print contained a large amount of manganese. This enabled a hypothesis to be put forward. The print had been previously bleached with a chemical no longer used for this purpose, potassium permanga- nate. The print had been insufficiently washed and divalent manganese had been left behind. On oxidising with the bleach Fig. 1. Three Chinese realgar statues this had turned into manganese dioxide. The stain was easily removed using an acid reducing agent, h ydroxylammonium chloride,s and the paper was subsequently washed and de-acidified. Manganese containing stains can also be found on excavated pottery. Most brown stains on this type of material are considered to be iron stains or mould stains and there are treatments to deal with these. However, pots from one ancient Greek site had surface stains wbich were very difficult to remove. A polished cross section of a typical surface was studied in the scanning electron microscope and showed that the stains contained manganese and that they could be removed with hydroxylammonium chloride.6 Analysis can be invaluable in solving problems which arise in the conservation and care of antiquities, but the result of an analysis is often not the complete answer to the problem. Interpretation of the result is the most important part of the operation and needs a thorough knowledge of all of the processes and problems inolved. References 1. Oddy, W. A., Rev. Lithoclastia, 1976, 2, 3. 2. Barton, N. G., andBlackshaw, S. M., Rev. Lithoclastia, 1976,2, 11. 3. Daniels, V., and Ward, S., Stud. Consent., 1981, 27,58. 4. Daniels, V., MASCA J . , 1983, 2 , 170. 5. Baynes-Cope, A. D., Pap. Conserv., 1977,2, 3. 6. Daniels, V., MASCA J . , 1981, 1, 230.

ISSN:0144-557X    

DOI:10.1039/AP9852200072

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 79 Principles of Automation and Applications of Robotics The following are summaries of three of the papers presented at a Joint Meeting of the Automatic Methods, Special Techniques and Microchemical Methods Groups together with the Microcomputer and Microprocessor Group of the RSC held on May gth-loth, 1984, in the Scientific Societies Lecture Theatre, London, W.1. The Why, When and Wherefore of Automatic Analysis D. C. M. Squirrel1 9 Graysfield, Welwyn Garden City, Hertfordshire In preparing this paper, it has been assumed that opinions are required with respect to certain general questions about automatic analysis. Firstly, what is it all about? Secondly, what advantages will it give in my situation? Thirdly, where do I start or given what I now have, and in the light of the newer technology, where do I go from here? The object, therefore, is to try and help the thought processes in starting to clarify some of these points.Why Bother? The overriding and short answer to this question is “To improve performance” and several factors will contribute to this improvement: better precision or accuracy; improved sensitivity; improved selectivity; faster analysis; greater throughput; more effective data handling; better communica- tion to process and business management (better control); and savings in labour costs. All of these factors should be examined in each and every case under consideration for automation. What are the overriding needs in each situation? The answer may greatly affect the system or instrument that one chooses to buy, assemble or develop.There are, of course, other motivating factors for automa- tion such as: keeping up with the “competition”; preparing for the future; legislative requirements; market requirements and product selection; and health and safety requirements. These factors and more can be encompassed by the general remit of the analyst to provide sound qualitative information and opinion, together with quantitative figures of the required accuracy or precision, at a frequency appropriate to each application or request. This might require several hundred analyses per day for a process application, through twenty per day to one per week or month in the laboratory. When to Automate For most of us the improvement of our laboratory or other analysis facilities is an evolutionary process, occurring when we replace equipment or start up a new technique to meet a particular demand.Very seldom do we have the pleasure of the responsibility for planning, designing, equipping and starting up a new laboratory to satisfy well defined needs within the fields of our past experience. Although such a “green field” situation is, in theory, the easiest time to set up for automation, the pressure to “get it right” is enormous and all decisions must be carefully researched: in particular, the likely changes or additional requirements for the future. Where do we Automate? For those of us who are wholly laboratory based, there is, of course, only one answer to this question. For many, however, particularly those in industry, where the analytical require- ments relate to process and quality control, process investiga- tion or development, other options are open.We may still use a central laboratory, and in some instances combine this resource for research and development with that for quality/ process control. Frequently, however, there is a requirement for the analyser to be near or on the plant itself. We may then require the plant laboratory, the on-plant analyser house, the on-plant free-standing analyser or the truly on-line analyser. All have their merits but all require different analyser design and operational considerations. The central or research laboratory will normally have a higher proportion of well qualified and experienced staff, capable of dealing with any problems occurring with sophisti- cated instrumentation and capable of modifying methods and choosing chemistries to suit abnormal samples or analysis requirements. The plant laboratory may be staffed by people trained only in routine operations and thus not always able to deal quickly with abnormalities occurring with instrumentation or samples.This environment may be less clean and direct senior or expert supervision may be minimal. Quality assurance organisation and diagnostic instrumentation is thus of importance. The analyser house, now becoming a very popular home for both laboratory and process analysers on the plant, provides a clean and safe environment in which each analyser may serve more than one process stream from samples piped to it.Analyser house equipment is normally required to operate completely unattended and thus full automation and reliability is essential. Manual intervention for maintenance or check calibration is, however, much easier than with an on-line system. How? The Decision Making Process First, it is necessary to look at the different requirements of an analyser for research and process/quality control (see Table 1). The differences listed in Table 1 are relevant to our discussions. Whoever raises the need for an automated analyser, all must be convinced that the need is real and the requirements well defined. There is thus an important consultation and communi- cations exercise here which must not be neglected, particularly when we are concerned with the “green field” situation.Some very clear definitions of responsibilities must be established right from the start and the analyst will need to obtain very clear agreement on the over-all objectives, time scales and budget limitations, together with the likelihood of any future changes, expansions or contractions in analysis requirements. Some questions to which answers are required are listed80 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 below and clearly each will raise a whole list of subsidiaries, which must also be dealt with in detail. Exact information required from each analyser. Frequency of analysis required. Speed at which results are required. Accuracy or precision necessary. Action to be taken on results and who needs to know. How is action to be carried out? What data handling is required-averages, trends, etc.Are alarm signals necessary? What happens if analyser fails? Back-up. Is some operator intervention rather than full automation an advantage. What are the cost limitations-capital and revenue. Technical details concerning the nature of the samples and the process. Armed with all the necessary facts it will be the responsibility of the research analyst, working in conjunction with his instrument development colleagues, to recommend and, if necessary, develop the required hardware to set up the system. They should prepare a short list of possible methods and arrange for any exploratory work, feasability studies, instru- ment trials, etc., to be carried out. Table 1. Instrument requirements Important factors Process control Research Speed Flexibility High reproducibility Maximum information Adequate sensitivity High accuracy Simplicity of operation High sensitivity Ease of calibration Reliability Minimum of maintenance Less important factors Flexibility Speed High absolute accuracy Simplicity of operation Ease of calibration Operator attention As a result of such investigations it is usually possible to decide on the best purchase or line of development to take.If the latter is necessary, re-consultation with all others con- cerned is advisable to make sure that requirements have not changed and to provide an opportunity for their ideas, criticisms and suggestions to be taken into account at the design stage. The cost estimates must be approved at the appropriate level.Whatever the system, a detailed manual and full software documentation should be considered essential, particularly if the latter was developed in-house. Operators and Training Operators of high productivity analytical instrumentation should, in my opinion, have received a good grounding in general analysis and have shown corn patability with instrumen- tation with an aptitude for dealing with computerised systems. The training on a complex system should be made interesting and a reasonable understanding of the essential theory imparted at an early stage. “On the job” training should have a little input each day, with practical runs on real samples to consolidate the points learned. Right from the start the trainee should be encouraged to pay particular attention to trouble shooting and fault finding procedures and to the method optimisation sequences if these functions are not automated.The instrument operator must be encouraged to give attention to technical improvements, methods of working, maintenance of precision, the simplification of sample prepara- tion procedures and the development of new applications. Involvement in these areas is important to the person who is to maintain a high interest and rate of routine output. Principles The following guidelines summarise some essential principles for successful automation in analysis: have an open minded initial approach; obtain a clear definition of requirements; establish a clear allocation of responsibilities; ensure good communications; facilitate inter-disciplinary co-operation; remember the virtues of simplicity; do not make if you can buy, but try before you buy; make proper maintenance arrange- ments; arrange proper operator training and motivation; make full use of microprocessor - computer facilities, within or available to the system, to provide summary reports, diagnos- tics, instrument status readout, statistics, etc.; ensure correct housing and positioning of analyser ; provide for adequate calibration and other quality assurance safeguards; research the chemistry and physics to be used very carefully. Once fully commissioned, the performance of the system should be closely monitored and any adjustments or modifica- tions made fully documented. Introduction to Robotics P. C. Hills Mechanical Design Branch, Royal Military College of Science, Shrivenham, Swindon SN6 8LA Robotics is a new word, but humankind has always striven for ways of making work less tedious, less tiring and less dangerous.Robotics is just the latest way of describing the most recent, most flexible method of providing help for humans. Various definitions of robots exist but most now settle on some programmable piece of machinery, which we somehow expect to possess at least partially human characteristics, and this would agree with Capek’s first use of the word in 1920 (robota is Czechoslovakian for forced labour). The world population of robots is currently about 37 600, of which 1753 are in the United Kingdom. They are mainly found in the manufacturing industries and the British Robot Associa- tion mentions no classification such as “Chemistry” or “Analy- sis.” The recent history of robots began with teleoperators for handling radioactive materials and these were comparatively simple mechanical devices.The control aspects have been developed and such devices as “The Wheelbarrow” are now available, using electrical control for inspection, entering cars and buildings and disposing of bombs. Other teleoperator applications include deep-sea repair on oil rigs and sunken vessels. Industrial Robots and Control Much current thinking and development effort is devoted to industrial applications and some general principles are evol- ving. Power can be electrical, hydraulic or pneumatic, the first two having the advantage of more positive displacement than air, which can impart a jerky motion to the “payload,” becauseANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 81 of its low stiffness and friction in the mechanical parts of the system.Control can be by microprocessor, via a stepper motor, which uses its memory of the most recent position of the free end of the robot as the starting point for the next movement. This can cause problems if slip occurs due to overload because there is no feedback and the robot will then always be out of step with what is wanted. However, stepper motors are simple and cheap, and are common on small articulated-arm robots for which there are 5 or 6 joints (or axes), each having its own motor operated by tendons. Alternatively, control can be achieved with a closed control loop in which the microprocessor dictates action and ceases this action when information is passed back from detectors saying that the required motion has been achieved.This is common on large devices, but can sometimes suffer from instability if the payload has more inertia than the robot has been designed for. Hunting by the free end is reduced by having dead zones, which effectively means that the system is happy if the free end stops within a certain, pre-defined distance of the required position, which itself implies poor repeatability. Again these devices have 5 or 6 axes and most robots can operate all axes simultaneously to give a smooth trajectory for the payload. Robot Geometry Commonly one finds articulated-arm robots, which are similar to the human shoulder, elbow, wrist and hand.However, other geometries exist using Cartesian, Cylindrical and Spherical co-ordinates. The choice of geometry is fairly arbitrary, but generally the inherent stiffness of the last three make them suitable for carrying heavier loads than the articulated arm. The prediction of the position of the free end, or payload, is performed analytically by determining the relative joint rotations and translations. Most authorities recommend the use of homogeneous co-ordinates for these calculations. This leads to four variables defining a point in three-dimensional space and a plethora of matrix multiplications. Teaching the Robot Programming languages that enable the operator to instruct the robot in simple descriptive words (like Move to A, Pick Up B If It Is There) are under development, but currently teaching the robot is restricted to two main forms.Many robots can be positioned manually or via a “teach pendant” and the positions read into computer memory. Other devices can accept instructions from a BASIC program using PRINT statements to an output port to which the robot is connected. Combinations of these exist: the Sykes Microbot can be programmed from a pendant and the results dumped into the memory of a computer. Once any of this information is in the computer it can be stored more permanently on tape or disc, although some robots have the ability to retain many programs in their own semi-permanent memories. The Future A survey of current robot applications shows them to be accurate and capable of replacing human beings for a wide range of tasks. The future will bring improvements in control but even more improvements in sensing: sight, touch, even smell.The biggest single improvement will be the reduction in cost of robots and their ancillaries. This has been the history of all such devices: the more that are made the cheaper they become, and so more are made and more are used. . . . Perhaps the biggest problem will be finding what to with the time that the robots have freed for us. Bibliography Soedel, W., and Foley, V., “Ancient Catapults,” Sci. Am., March, 1979. Capek, K., in a play “Rossum’s Universal Robots,” 1920 [although he had referred to a robot (robota = forced labour, Czech) in an earlier essay]. British Robot Association, “Robot Facts 1983 ,” December, 1983.Kato, I., “Mechanical Hands Illustrated,” Survey Japan, 1982. Smith, D. N., and Wilson, R. C., “Industrial Robots: A Delphi Forecast of Markets and Technology,” University of Michigan, 1982. Robot Sensing J. J. Hill Department of Electronic Engineering, The University The Need for Sensing A robot is a programmable machine which is designed to manipulate and transport workpieces in a variety of industrial tasks. The majority of devices currently in operation in industry are “first generation” robots, having relatively little perception of the environment in which they work. This sensory limitation is unimportant in applications such as spot welding or paint spraying, where precise positioning is not required, but in complex assembly tasks, or in coping with a less structured environment, sensors are required. Sensory robots are referred to as “second generation” devices,l and in this instance it is no longer necessary to know the precise position of all components in the workplace because the robot can use its sensors to determine their location.With appro- priate software the robot is able to make “intelligent” decisions: for example, to recover from an error situation when a component has been dropped. A wide variety of-sensing mechanisms are available and these are outlined in the next section. Sensor Types Sensors external to the robot transmit information about the of Hull, Hull, HU6 7RX real world (workplace) to the robot using one or more of the main sensing mechanisms of vision, tactile sensing and acoustic sensing.Vision Sensing Vision sensing has generally attracted the most attention and research effort of all the robot senses, and commercial robot vision systems are now available from a number of manufac- turers. The basic vision sensing devices are: TV camera; solid state area array; solid state line array; photodetector; laser. The vision sensor is often located above the work area, but this approach suffers from two main disadvantages in that the robot arm will obscure the work area and calibration must be maintained between the camera and robot frames of reference. A more attractive approach is to mount the vision sensor on the end-effector as an “eye in the hand,” which requires that the sensor be rugged and small enough to not effect the payload of the robot.The basic TV camera, although inexpensive, is too large to be carried by the robot arm and suffers from problems of non-linearity. Solid-state cameras are now manufactured so that the “front end” can be removed from the main housing, allowing the imaging section to be mounted on the robot82 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 gripper. These sensors are based on a charge-coupled device (CCD) area array with a resolution of 256 x 256 picture points (pixels) or better, but are currently rather expensive for the majority of robot applications. Line-scan sensors based on a CCD or diode array and manufactured to contain between 128 and 2048 elements are useful if there is relative motion between the sensor and the workpiece. 2 The basic photodetector is a photodiode, a light sensitive electronic element which is usually used in conjunction with a light emitting diode (LED) as a crossfire, emitter - receiver pair to detect the presence or absence of a workpiece.This is often referred to as proximity sensing although capacitive and inductive transducers can also be used to detect workpiece proximity. The laser is not a sensor but can be used as an intensive source of light and is sometimes used in conjuction with a photomultiplier for distance ranging or three dimensional imaging .3 Tactile Sensing Tactile sensing involves physical contact between the robot end effector and workpiece. Although less research work has taken place in this area, tactile sensing is important in assembly and other applications involving precise mechanical contact between the robot and workpiece.A number of tactile sensing mechanisms are available: contact switch; strain gauge; carbon fibre materials; piezoelectric materials. A contact switch or microswitch is often used to detect contact between the robot end effector and object giving a simple binary contactho contact decision. Strain gauges, carbon fibre materials and piezoelectric materials, on the other hand, can be used for force sensing, which is required in a number of robot applications, A particular need is the measurement of components of force and torque (three of each) between the last robot link and the end effector. Strain gauges and carbon fibre materials change resistance under stress, and piezoelectric materials generate an electric charge when subjected to a mechanical strain.There is also a need to extend force sensing from a single point to an array of points, commonly known as a tactile imaging array, and a sensor of this type has been developed at the Hirst Research Centre.4 Such sensors enable the robot to “feel” the shape of a component while held by the gripper. Acoustic Sensing Ultrasonic transducers can be used in range measurement, as in the Polaroid Camera, by emitting a pulse of ultra-sound (usually around 40 kHz) and measuring the time taken for the transmitted pulse to be reflected off the target and detected again. This approach could be useful with mobile robots, but has not been widely used to date. The use of scanned ultrasonic arrays for 3-D imaging is an active research area, but the resolution that can be realistically obtained from this type of array will not be high.Multi-sensing: a Case Study An example of a multi-sensory robot system5 used in an assembly cell to assemble high powered semiconductor diodes is shown in Fig. 1. In this approach, processing is distributed amongst a number of processors, which communicate via a common communications bus, ROBUS. The master processor stores the “task tree” and allocates tasks to the slave processors, which can operate concurrently. Each sensor has its own processor and a separate processor enables efficient communciation with the robot. The assembly problem involves five components, viz., molybdenum base, first solder foil, diode pellet, second solder foil and terminating “C-crimp.” Each diode unit, together with a graphite weight, is assembled into a graphite jig which holds a number of assemblies in place while they pass through an oven.The solder preforms and the molybdenum base are fed from magazines and inspection of these components is unnecessary. The “C-crimps” are fed from a bowl feeder and picked up from the end of the track by a vacuum sucker fitted to the gripper. Sensors are used to detect components at the end of the track and to indicate successful pick up. The shank of the “C-crimp” cannot be assumed to be perpendicular to the contact end, and vision, in the form of a fixed, low resolution (32 x 32) visual inspection station is used to determine the amount of correc- tion required to position the shank in the hole in the graphite weight. \ (ROBUS) Robot communications bus \ I I 1 Parallel VLR Robot [Supervisory I interface binary PA interi I LSI 11/23 I Frame grabber processor processor Serial I/O controller LSI 1 1/02 - Detachable ‘Is sense head sensor “ub CCD-WMC Robot Fig.1. Multi-sensor system architecture. Key : CIS, camera inspection station; XC and ZC, axis cameras; WMC, workspace monitor camera; GC, gripper cameraANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 Analytical Abstracts endeavours to cover the whole field of analytical chemistry, providing more than 12,000 abstracts per annum of papers and books considered to be of importance and interest to analytical chemists. indexes are published annually. 12 issues per annum (plus indexes) ’ ~ 83 The diode pellets are circular or hexagonal in shape, depending on the diode power rating.They are fabricated by etching from a silicon wafer and contain typically 25% reject shapes. Vision is used to both locate and inspect these components. A low resolution camera (32 x 32) is mounted on the gripper and is used for fine location and pellet inspection. The high resolution (256 X 256) work monitor camera is focused over the work area and is used for coarse component location and monitoring each part of the assembly process. Conclusion The majority of robots currently operating in industry are first generation devices equipped with little more than proximity sensors. Second generation robots with an advanced sensing capability are required to extend the application of robots into precision areas.References 1. Pugh, A., “Second Generation Robotics,” “12th International Symposium on Industrial Robots,” IFS (Conferences) Ltd., Paris, 1982, pp. 1-8. Johnson, D. G., and Hill, J. J., “A Modular Linear Array Camera for Robot Vision,” “Digital Systems for Industrial Automation,” Vol. 2, No. 3, 1984, to be published. 3. Nitzan, D., Brain, A. E., and Duda, R. O., “The Measurement and Use of Registered Reflectance and Range Data in Scene Analysis,” Proc. IEEE, 1977, 65, 206. Robertson, B. E., and Walkden, A. J., “Tactile Sensor Systems for Robotics,” “Third International Conference on Robot Vision and Sensory Controls,” SPIE and IFS (Conferences) Ltd., Cambridge, Mass., 1983. Burgess, D. C., Hill, J. J., and Pugh, A., “Multiple Vision Sensing in Robotic Assembly: A Case Study,” “Proceedings of the 1st World Conference on Robotics Research,” Society of Manufacturing Engineers, Bethlehem, PA, 1984.2. 4. 5 . Three of the WorldsS leading Analvtical Tournals * The Analyst 1 An international journal of high repute containing original research papers on the theory and practice of all aspects of analytical chemistry drawn from a wide range of sources. It also publishes regular critical reviews of important techniques and their applications, short papers and urgent communications (which are published in 5-8 weeks) on important new work, and book reviews. 12 issues per annum (plus index) SUBSCRIPTION RATES 1985: The Analyst UK f134.50, USA $260.00, Rest of World f141.00 Analytical Abstracts UK f 199.50, USA $385.00, Rest of World f 209.50 Analytical Proceedings UK f63.50, USA $123.00, Rest of World f67.00 The Analyst, Analytical Abstracts, and Proceedings UK f330.00, USA $638.00, Rest of World f347.00 Analytical Proceedings Analytical Proceedings is the news and information journal of the Analytical Division. It contains special articles, reports of meetings, extended summaries of original papers, safety articles, details of recent legislation, surveys of equipment, and many other items of general interest to analytical chemists both in Britain and overseas. 12 issues per annum (plus index) Analytical Abstracts As above with Abstracts on one side of the paper UK f345.00, USA $666.00, Rest of World f362.00 The Analyst and Analytical Abstracts UK f293.00, USA $566.00, Rest of World f308.00 As above with Abstracts on one side of the paper UK f312.00, USA $603.00, Rest of World f327.00 The Analyst and Proceedings UK f 169.00, USA $327.00, Rest of World f 178.00 Analytical Abstracts on one side of the paper UK f217.50, USA $420.00, Rest of World f228.00 ORDERING: Orders should be sent to: The Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 lHN, England. The Royal Society of Chemistry Burlington House Piccadi I I y London W1 V OBN

ISSN:0144-557X    

DOI:10.1039/AP9852200079

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

84 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 Equipment News Spectrometer The ICP/6500 inductively coupled plasma emission spectrometer is capable of ana- lysing trace elements routinely at a speed of over 20 elements min-1 and of deter- mining samples at any wavelength with- out prior wavelength calibration. Ana- lyses are performed at the optimum analy- tical wavelength for each element or sample matrix. The optical system uses a dual-grating monochromator covering the range 17&900nm and it can be purged with an inert gas. The plasma torch is demountable to reduce maintenance costs, and the complete sample introduc- tion system is resistant to attack from corrosive sample solutions. The ICP/6500 is controlled through the makers’ 7300 Professional Computer. For quantitative multi-element analysis, methods can be built containing up to 108 wavelengths, or the Qmode permits semi-quantitative analysis of a sample using stored stan- dardisation information.Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Spectrophotometers The Shimadzu UV-120 single-beam, non- scanning instrument is available in both an ultraviolet - visible and a visible version. Both have sealed monochroma- tor optics: the standard version features high optical density capability, which means less sample dilution, and the four- cell sample compartment allows measure- ments of standards as well as samples sequentially. The Shimadzu UV-260 has the ability to look at the absorption at six pre-selected wavelengths in the range 900 nm-190 ym. These absorbances can then be multiplied by a factor and summed for empirical multi-component analysis or pre-determined factors entered for conventional 2-6 component analysis from real-time or memorised spectra.Spectra can be added, subtrac- ted, divided or multiplied. The UV-260 allows memorised time course spectra to be recalled to the visual display unit and the absorption or AAlAT values to be displayed at any time during the reaction, or the display of absorbance versus time on the integral plotter with AAlA T multi- plied by a factor to give concentration values. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. Spectrofluorimeter and Accessories The Shimadzu RF540 can monitor chemi- luminescence reactions at constant excita- tion and emission wavelengths; alterna- tively reactions can be monotaped by repetitive overlay scanning.Up to 100 repetitive scans with delays of up to 100min can be programmed. In either monitored mode a parallel head printer draws a frame around the spectrum or trace for effective presentation and auto- matic integration and smoothing, giving optimal recording of the spectrum irre- spective of scan speeds selected. Optional accessories include a choice of flow through cells, test-tube holders for the sample compartment, a bottom rinse sam- ple stage which reduces the minimum measurable volume to 1.5ml and a ther- mostatted cell which, in conjunction with a thermocirculator or a heater - chiller, allows temperature control of the sample. V. A. Howe and Co. Ltd., 12-14 St.Ann’s Crescent, London SW18 2LS. Flame Photometer The PFP-7 digital instrument incorpor- ates an automatic flame failure cut-out device. It also features a linearity better than 2% fsd, for sodium (3 p.p.m.), potassium (3 p.p.m.) and lithium (5 p.p.m.), set to full scale, and a specificity less than 0.5% from a concentration of interference of Na, K, Li, Ca and Ba equal to the concentration of the element under analysis (for Na, Li and K only). A 34-digit LED display of 0.6 in character height registers readings between 0 and 199.9 in relation to full-scale readings of 3-100p.p.m. for Li, 3-100 for Na and 5-100 for K. Reproducibility is 1 YO CV for 20 consecutive samples, with 10 p.p.m. set to full scale, using samples of 2-6 ml. Jenway Ltd., Gransmore Green, Fel- sted, Dunmow, Essex CM6 3LB.Ion Chromatography Columns The Hamilton PRP x 100 is a resin based anion column specifically designed for ion chromatography and it can be used exclu- sively in the non-suppressed mode. Col- umn eluent can be used in the range pH 1-13, and up to 100% of organic modifier can be employed. The column is available in three sizes: 100,150 and 250 mm. Every column includes the test chromatogram from the individually tested column. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. Gas Chromatography Equipment A range of gas chromatographs features serial detector capability, direct injection, no make-up gas and capillary continuous thermal conductivity detectors. Also featured are thermionic ionisation detec- tors, in which the response can be tailored by simple adjustment of the operating conditions.In addition, a laboratory data station and a range of software and operating systems are available. Gow-Mac Instrument Co. (UK) Ltd., Gow-Mac House, P.O. Box G13, Gilling- ham, Kent ME7 4HA. Gas Chromatography Sample Injection System Sichromat Headspace 6, a supplementary module for the makers’ Sichromat gas chromatographs, is for determining vola- tile components in heterogeneous sam- ples. Sample input can be controlled manually or fully automatically by the Sichromat computer. The temperature range of the sample bottles is selectable between 60 and 160°C, and the time for adjusting the phase equilibrium can also be selected. The magazine of the injection system can take six samples, which are introduced fully automatically and sequentially.Siemens Ltd., Siemens House, Wind- mill Road, Sunbury on Thames, Middle- sex TW16 7HS. Gas Chromatograph Injector The Programmable Temperature Vap- oriser (PTV) injector for use with the makers’ Model Sigma 2000 gas chromato- graph can be used to inject a wide range of samples of varying volatilities, polarities, stabilities and concentrations. Samples are injected into a cold environment, so that problems associated with sample discrimination from the syringe needle, decomposition of labile compounds and quantification errors are reduced. For routine analyses the system offers the advantages over on-column injection that an autosampler can be used, no prior sample dilution is necessary, there is no build-up of involatile residues in the column, pre-column separation can be effected, narrow bore columns can be used and sample injection is straightfor- ward by using standard syringes.Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA.ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 85 Gas Chromatography Equipment An air generator is available that is capable of supplying air for as many as 10 gas chromatographs; it is a compact bench-top unit in which ambient air passes through a 4pm dust filter, a con- denser, a two-stage adsorption filter and an adsorption column. Also available is a complete station, the Gas Clean Unit, for the purification, regulation and monitor- ing of gases; all filters needed for the operation of one or more gas chromato- graphs can be combined on the unit, by using these columns.They, particu- larly the covalent columns, can be used for preparative work. As much as 100 mg of a component can be isolated from a single injection into a 10 mm i.d. covalent column. The 4.6 i.d. columns average 40000 plates m-1, whilst the 10mm i.d. covalent columns average 55 000. Chrompack UK Ltd., Unit 4, Indescon Court, Millharbour, London El4 9TN. Ionised Calcium Analyser In the Radiometer ICA 113 system the Chrompack Gas Clean Unit eliminating the need for a number of independent connecting units. A capillary column is available, which can be installed instead of the conventional packed col- umn without any modification of the chromatograph. Made of fused silica, it is a 10-m wall coated open tubular column with an internal diameter of 0.5 mm.The coating is either the apolar phase CP-Si15 CB or CP-Sil8 CB with a film thickness of 5 pm. It is also available with the medium polar CP-Sill9 CB and the polar CP-Wax 57 CB with 2 pm films. Chrompack UK Ltd., Unit 4, Indescon Court, Millharbour, London El4 9TN. Thin-layer Chromatography Accessories Available for use with the Shimadzu CS 930 TLC Scanner are a hand-held mer- cury lamp, which allows ultraviolet absorbing regions to be viewed at the initial setting-up stage, slab and disc holders, which permit densitometry of gels immersed in solvent, a PTFE-coated film holder to be used in densitometry of chromatographic filter-paper, filmy TLC plates or autoradiography film, the Pro- gram Cassette CCS-2, which performs rapid automatic mapping profiles, and a recorder mount.V A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. Optically Active HPLC Columns The enantiomeric purity and absolute configurations of samples can be deter- mined down to the sub-nanogram range TNCl turntable - conditioner operates in conjunction with an ICAl ionised calcium analyser and a PRS 12 alpha printer. The system is dedicated for the automatic determination of ionised calcium and pH in whole blood, serum or plasma. The TNCl overcomes the problem of pH shifts due to metabolic processes and the loss of C02 by equilibrating the sample with a C02 gas mixture, returning the pH close to 7.4, thus enabling aerobic sam- ples to be used for ionised calcium diagno- sis.The TNCl also enables batch analysis to be carried out. It can be fitted to an existing ICAl unit, or the ICA 113 can be supplied complete with PRS 12 printer. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. Pipetter - Diluter - Dispenser The Accu-Prep 211 has a single-channel two-syringe system and performs dilu- tions up to 1 : 1000 using the full stroke of both syringe volumes. It performs dilu- tion, multiple dispensing, transfer pipet- ting and titration processes via a patented direct drive stepper motor. Microcomputer-controlled, the system stores up to 50 programs, which are protected for 48 h in case of power failure. Beckman Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buck- inghamshire. Pipette Pump The Pumpette eliminates oral contact with pipettes and ensures precise filling and discharge. The Standard Pumpette takes pipettes from 1 ml upwards, while the Mikro Pumpette is for use on pipettes up to 2ml.Clandon Scientific Ltd., Lysons Ave- nue, Ash Vale, Aldershot, Hampshire GU12 5RQ. Headspace Concentrator The Tekmar DHC-1 dynamic headspace concentrator is designed for heated sam- ple application. It features ten automatic sampler positions, each with built-in sam- ple heater. It is fully automatic, allowing 10 samples per cycle; samples are heated up to 200°C and lines and valves are independently heated to 250 “C. The DHC-1 also includes 20 needle spargers, 20 sample sparge needles, Tenax Trap, Tenax - silica gel trap, blank trap tube, instruction manual, purge gas trap and spares, fusedlights and ferrules.Analysis Automation Ltd., Southfield House, Eynsham, Oxford OX8 1JD. Titration System The Radiometer RTSS recording titration system features the ABU80 autoburette and allows the determination of “S”- shaped curves, pH stat, end-point, pH and redox potentials, etc. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. Computerised Densitometer “Appraise” offers a 5-7s scan time. Its fraction selection facilities make it, in general, unnecessary to edit patterns, but a keyboard simplifies sophisticated edit- ing. Automated scanning provides pro- grammable automatic step-over from track to track of all common electro- phoresis media. Appraise can check the calibration of absorbance and fluor- escence. The high resolution CRT and automatic delimiting programme offer a detailed display of each pattern on the CRT for preview and the ability to restore86 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 and display the unedited scan.There are facilities for instant access to 10 pro- grammable test selections and random access and viewing of 20 patterns without re-scanning. A 160-pattern option is avail- able. Beckman Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buck- inghamshire. Oxygen Monitor The Systech ZR89 Oxymonitor, based on the makers’ microprocessor-controlled dual-readout Harmony meter; measures the trace oxygen content of all inert (non-explosive) gases and CO2 over one fixed range and a further three specifiable ranges from 0.01 p.p.m. to 100% oxygen content.To avoid the taking of false readings before the instrument is properly warmed up the “alarm” and “temp” LCD “flags” are displayed until the correct operating temperature is reached. In addition to the digital reading the Har- mony incorporates an analogue trend bar, which moves in proportion to the signal. The ZR89 can be calibrated from the front panel, using ambient air as the Cali bration medium. Sifam Ltd., Woodland Road, Torquay TQ2 7AY. Flammable Gas Monitor The Warnex B provides up to 12 hours’ continuous monitoring of an atmosphere and gives an immediate audible and visual alarm in the presence of flammable gases or vapours. The alarm threshold is adjus- table. Approved to BASEEFA, the War- nex B is intrinsically safe. Draeger Safety, Draeger House, Sunnyside Road, Chesham, Buckingham- shire HP5 2AR.Water Monitors The DOT ONE modular control network provides accurate single station or cen- tralised data collection for water systems of varying purities up to 18MQcm-1 resistivity. It features multi-sensor resis- tivity - conductivity, temperature, pH, flow, pressure or % rejection. Its multi- station transmitter - master control system permits serial or selective data collection at a central or remote control and display. Using the master display with its LED digital readout up to 32 sensor readings can be automatically monitored through the appropriate transmitters at distances up to 1000m. The master module can be supplied with an integral RS232 interface. Semat Technical (UK) Ltd., 223 Hat- field Road, St.Albans, Hertfordshire AL14UN. Colorimeter The PCO-2 digital calorimeter provides three modes of measurement: trans- mittance from 0 to 100% to a resolution of 1.0%, absorbance from 0 to 1.5 to a resolution of 0.01 and two electronically linearised concentration ranges which offer coarse and fine measurement of absorbance readings. Incorporated are eight switch-selectable filters, which cover the instrument’s wavelength range in increments 430,470,490,520,540,580, 600 and 710nm. Jenway Ltd., Gransmore Green, Fel- sted, Dunmow, Essex CM6 3LB. Magnetic Susceptibility Balance The balance employs moving magnets and stationary sample tube. Magnetic susceptibility is calculated from an instan- taneous digital readout by using a simple equation. Sample weights of around 250 mg suffice for accurate measurement. and agarose in the appropriate sizes and grades, respectively, together with a full list of buffers and stains, staining solutions and clearing oil. BDH Chemicals Ltd., Broom Road, Poole, Dorset.Haematology Analysers Two semi-automated instruments are announced: Models M2 and M4. The former offers white cell count and hae- moglobin; the latter performs a four- parameter profile consisting of white blood cell count, haemoglobin, red blood cell count and haematocrit. Coulter Electronics Ltd., Northwell Drive, Luton, Bedfordshire LU3 3RH. Johnson Matthey magnetic susceptibility balance The balance is portable and can be used with a wide range of diamagnetic and paramagnetic materials. Johnson Matthey Equipment Ltd., South Way, Exhibition Grounds, Wem- bley HA9 OHW. Digestion System A range of Gerhardt Kjeldahl systems includes macro and semi-micro block digestion systems, temperature - time programmers, Vapotest distillation units for rapid distillation direct from flasks and tubes in the manual, semi-automatic or automatic modes and a Turbosog suction system for fumes removal.A new Kjel- dahl digestion system extends the basic digestion block to a multi-purpose ana- lyser. By using interchangeable insert racks and condenser racks it can be applied to four determinations: Kjeldahl nitrogen, COD, hydroxyproline and trace metal analysis. F.T. Scientific Instruments Ltd., Sta- tion Industrial Estate, Bredon, Tewkes- bury, Gloucestershire GL20 7HH. Electrophoresis Reagents The Electran range has been enlarged to include materials for serum protein analy- sis.These include both cellulose acetate Stat Analyser The Gemstar stat analyser allows comple- tion of a 12-test profile in 4-13min, depending on the methods involved. A full range of diagnostic kits is available, including iron, TiBc, magnesium, chloride, acid, phosphatase and immuno- chemistries. Ultrolab. Furnaces The ECF-11 series of programmable chamber furnaces offers the options of four chamber sizes (2.6,3.9,5.8 and 9.1 1) with power ratings from 2-3 kW. The wire heater elements for the hot chamber (constructed of interlocking refractory tiles) are embedded in the chamber side- walls, making the furnace suitable for operation under semi-corrosive condi- tions. Safety features include a thermal fuse for over-temperature protection, a door switch that de-activates the a.c.mains contactor when the door is open and a door designed so that the hot face is away from the operator when it is open. Lenton Thermal Designs Ltd,, 12/14 Fairfield Road, Market Harborough, Leicestershire LE16 9QQ. Vacuum Oven The unit, manufactured by Vismara,ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 87 Italy, has a chamber size of 651 with flexible shelf arrangements and a maxi- mum working temperature of 2000 “C. Supplied for bench mounting, it is com- plete with temperature controller, vac- uum gauge and large diameter pumping port for drying applications. Edwards High Vacuum, Manor Royal, Crawley, West Sussex RHlO 2LW. Flask Heater The “Labsafe” heater is of ceramic con- struction and thus offers good electrical and thermal insulation properties.It features a modular control system, a selection of “labsafe” controls being easily interchangeable by means of spe- cially designed in-line connectors. Isopad Ltd., Stirling Way, Boreham- wood, Hertfordshire. Literature A brochure describes the VG9000 glow discharge mass spectrometer, explaining the operating principles and the advan- tages over conventional systems. The high dynamic range, spanning concentration levels varying by as much as 108, means that major and ul tra-trace components can be determined in a single measuring sequence. Examples described include the observation of lead, bismuth, arsenic and selenium in copper, and trace ele- ment determination in gallium arsenide.VG Isotopes Ltd., Ion path, Road Three, Winsford, Cheshire CW7 3BX. A leaflet gives details of the BT 2000 Series mains-powered instruments for continuous on-line measurement of trace oxygen in most process gas streams and the BT 200 Series of portable, battery- powered instruments. Bedfont Technical Instruments Ltd., P.O. Box 42, Streatham, London SW16 1JH. A brochure presents the AN10000 X-ray microanalysis system, capable of measur- ing, storing, analysing, displaying and manipulating X-ray and electron signals produced by scanning and transmission electron microscopes. It features a micro- computer with a 256K central processor, Winchester disk as standard and “Mouse,” which, when it is moved around on a flat surface, enables images or a cursor to be moved to enhance, clarify and speed up selections.Also features are a matrix printer - plotter and screen copy facilities. A range of software is available and may be modified using a FORTRAN programmer’s package. SCREED, a word processing package, enables users to pre- pare written results in a readily acceptable format. Link Systems Ltd., Halifax Road, High Wycombe, Buckinghamshire HP12 3SE. A leaflet describes the Fritsch Laborette 10 centrifugal laboratory sample divider, which divides material fed into it dis- cretely or continuously into 16 equal samples. A special feature is the ability to divide very fine materials, such as limes- tone, icing powder and flour, which tend to form bridges. Laborette can also be used to divide liquids or suspensions. Christison (Scientific Equipment) Ltd., Albany Road, East Gateshead Industrial Estate, Gateshead NE8 3AT. A leaflet presents the 1200 Series of pocket-size thermometers. These instru- ments are digital and two models make up the range: the Model 1208 covers the range from -25 to +700 “C and the Model 1204 offers k0.2 “C for temperatures from Digitron Instrumentation Ltd., Mead Lane, Hertford, Hertfordshire SG13 7AW. -50.0 to +199.9”C. A set of 13 application notes on the thermal analysis of fossil fuels has been published by Setaram. Each gives the experimental conditions and results. Brief technical details are given of heat flow calorimeters, differential thermal analys- ers and a Calvet high temperature cal- orimeter. Clandon Scientific Ltd., Lysons Ave- nue, Ash Vale, Aldershot, Hampshire GU12 5RQ. Analytical Division Schools Lecturer The Analytical Division Council, at its meeting on December 12th, decided to appoint as the Division’s Schools Lecturer for 1985/6 Dr. J. D. R. Thomas of the University of Wales Institute of Science and Technology. Ronald Belcher Memorial Lecture At its meeting on December 12th, the Belcher Memorial Lecture should be Council of the Analytical Division, on given by Mr. S. A. Johnson, SAC Student recommendation of its Honours Commit- at the University of Cambridge. tee, agreed that the 1st (1985) Ronald

ISSN:0144-557X    

DOI:10.1039/AP9852200084

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 87 Collaborative Studies Collaborators are required for the follow-’ ing projects. 1. The determination of 3-methyl-~- histidine in meat and meat products. 2. The determination of synthetic col- ouring materials in soft drinks. 3. The determination of dietary fibre (3rd part). Interested persons should contact Dr. Roger Wood, Food Science Division, Ministry of Agriculture, Fisheries and Food, 65 Romney Street, London SWlP 3RD.

ISSN:0144-557X    

DOI:10.1039/AP9852200087

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

88 ANALYTICAL PROCEEDINGS, MARCH 1985, VOL 22 Ronald Belcher Memorial Lectureship In recognition of the late Professor Ronald Belcher’s interest in education, the Council of the Analytical Division has inaugurated a Belcher Memorial Lecture to be given annually on an analytical topic by a graduate student. The award will be considered by the Honours Committee, acting on behalf of the Council of the AD. The aim of the award is to commemorate Professor Belcher as a teacher, by encour- aging students to make a positive contri- bution to, and take an active part in, the profession of analytical chemistry. Rules 1. 2. Candidates must currently be regis- tered postgraduate students of a British University or Polytechnic. The merits of a particular candidate may be brought to the notice of the Honours Committee by any super- visor of postgraduate students regis- tered with a British University or Polytechnic who desires to recom- mend the candidate, by letter addressed to the President of the Division.The letter shall be accom- panied by a paper written by the The award shall be made annually in December and shall be based on an over-all assessment of the originality of the work described in the paper and the significance of its contribu- tion to analytical chemistry. The winner of the award will be expected to present his or her work at the Research and Development Topics Meeting following the award. Student. 5. 6 . 7. given to the candidate, up to two years after the granting of the award, on presentation of satisfac- tory evidence of the candidate’s intention to attend such a confer- ence. An award shall not be made if it is considered by the Honours Commit- tee that none of the papers submit- ted reaches the required standard. The decision of the Council of the Analytical Division shall be final. Any alteration to these Rules shall be subject to the approval of the Council of the Analytical Division. The award will take the form of a Submissions should be sent to the presentation scroll plus a sum of President, Analytical Division, Royal 2150. This sum is to assist the Society of Chemistry, Burlington House, candidate to attend a national or London, W1V OBN. The closing date is international conference. It will be Monday, September 30th, 1985.

ISSN:0144-557X    

DOI:10.1039/AP985220088b

出版商:RSC    

年代:1985

数据来源: RSC