摘要:

of the Analytical Division ofThe Chemical SocietyCONTENTS35 CS Autumn Meeting37 Second Anglo - CzechSymposium on Electro-chemistry37 Reports of Meetings40 Summaries of Papers40 'Analytical Atomic SpectroscopySym posi urn'44 'A p pi ica t i o n s of An a I yt i ca ITechniques to IndustrialEffluents'47 'Analytical Techniques Used inI n d ust ry '49 Equipment News51 Conferences and Meetings53 Publications Received56 Analytical Division DiaryVolume 13 No 2 Pages 35-56 February 197PADSDZ 13(2)35-56(1976)ISSN 0306-1 396February 1976PROCEEDINGSANALYTICAL DIVISION OF THE CHEMICAL SOCIETYOF THEOfficers of the Analytical Divisionof the Chemical SocietyPresidentG . W. C. MilncrHon. SecretaryP. G. W. CobbHon. TreasurerJ. K.ForemanSecretaryMiss P. E. HutchinsonHon. Assistant SecretariesD. I. Coomber, O.B.E.; D. W. WilsonEditor, ProceedingsP C. WestonProceedings is published by The Chemical Society.Editorial: The Director of Publications, The Chemical Society, Burlington House, London, W1 V OBN.Subscriptions (non-members): The Chemical Society, Publications Sales Office, Blackhorse Road, Letch-worth, Herts., SG6 I H N .Non-members can only be supplied with Proceedings as part of a combined subscription with The Analystand Analytical Abstracts.0 The Chemical Society 1976Telephone 01 -734 9864 Telex 268001.The Annual MeetingonR and D Topics in Analytical Chemistrywill be held in theChemistry Department, University of ExeteronMay 4th and 5th, 1976Short papers will be presented describing the work carried out by post-graduate research students in universities and colleges and by young researchworkers in industrial and other establishments.Further information can be obtained from the Secretary, Analytical Division,Chemical Society, Burlington House, London, W1 V OBN

ISSN:0306-1396    

DOI:10.1039/AD97613FX005

出版商:RSC    

年代:1976

数据来源: RSC

摘要:

FebriLayy, 1976 ANALYTICAL DIVISION DIARY 55Analytical Division Diary, continuedMarch, continuedMonday, 15th, 6.30 p.m.: ChesterNovtlz West Region, jointly with the StanlowBranch of the Institute of Petroleum.“The Determination of Polynuclear AromaticHydrocarbons in Petroleum Products,” byG. B. Crump.Thornton Research Centre, Shell ResearchLtd., Chester.Thursday, ISth, 7 p.m.: BristolWestevn Region.“Environmental -4spects of Pesticide Analy-School of Chemistry, The University, Bristol.sis,” by J . Yates.Wednesday, 24th, 6.30 p.m. : LondoniVicrochemical Methods Gvoup.Discussion on “Some Snags in the Deter-mination of Boron,” to be introduced byD. A. T’antony.Savoy Tavern, Savoy Street, London, W.C.2.Thursday and Friday, 25th and 26th: Can-terburySouth East Region on “The Role of theAnalytical Chemist in the Protection ofSociety.”For further information see p. 52.University of Kent, Canterbury.Wednesday, 31st, 2 p.m. : LoughboroughEducation and Tvaining Group on “Teachingand Safety of Radiochemical Methods.”“The Teaching of Radiochemistry to Under-graduates, ’’ by G. Oldham.“Safe Handling of Radioactive Materials,”by H. D. Evans.Tour of the Radiochemical Laboratories.Room J/OO/l, Edward Herbert Building,University of Technology, LoughboroughAnalytical Division DiaryFEBRUARYMonday, 23rd, 8 p.m.: CreweNorth West Region, jointly with the SouthCheshire Branch of the PharmaceuticalSociety.“The Disposal of Toxic Waste,” by L. Knott.Crewe Arms Hotel, Crewe.Tuesday, 24th, 10 a.m.: SheffieldThermal Methods Group, jointly with theBasic Science Section of the British CeramicSociety on “The Application of Thermo-analytical Methods to the Testing of HighAlumina Cement Concrete.”Speakers: H.G. Midgley, F. W. Wilburn, I;. P.Glasser, Miss J . P. Dixon and H. A. Davies.Tapton University Hall of Residence,Sheffield.Thursday, 26th, 2.30 p.m. : LondonBiological Methods Group on “TransferableResistance Factors.”Speakers: N. Datta, J. T. Smith and H.Williams Smith.Pharmaceutical Society of Great Britain,17 Bloomsbury Square, London, W.C. 1.Thursday, 26th, 4.15 p.m.: AberdeenScottish Region, jointly with the Aberdeen andNorth of Scotland Section of the CS andthe Aberdeen University Chemical Society.“The Function of the Laboratory in anIntegrated Iron and Steel Plant withParticular Reference t o EnvironmentalControl,” by J .Little.Department of Chemistry, University ofAberdeen, Meston Walk, Old Aberdeen.Friday, 27th, 7 p.m.: ChepstowWestern Region.Discussion on “Whatever Happened toElectroanalytical Methods,” to be intro-duced by B. Fleet.Wye Room, George Hotel, Chepstow.Wednesday, 3rd: Newcastle upon TyneNorth East Region on “The Analysts’ Con tri-bution to the Welfare of the Public.”The Polytechnic, Newcastle upon Tyne.Thursday, 4th, 2 p.m.: LiverpoolNorth West Re.qion, Special Techniques andAutomatic Methods Groups, jointly with theCS/RIC Liverpool Section on “Electro-chemical Sensors in Difficult Environ-ments. ”“Use of ICI Developed Oxygen- and Chlorine-responsive Probes,” by J .M. Young.“The Determination of Gases in MoltenMetals,” by J . White.“Sensors in Plant Control,” by P. Palin.“Sterile Solutions,” by R . Hutchinson.The Polytechnic, Byrom Strect, Liverpool.Wednesday loth, 2.15 p.m. : SouthendEast Anglin Region, jointly with the CS/RICEssex Local Section on “High PerformanceLiquid Chromatography.”“The Instrumentation and Techniques ofHPLC,” by M. B. Evans.“The Practical Applications and EconomicConsiderations of HPLC,” by B. B. Wheals.“Procedures for Optimising HPLC Separa-tions,” by N. Parris.College of Technology, Southend.Wednesday, loth, 3 p.m. : NottinghamAnalytical Division : Annual General Meeting.Address of the retiring President : “TheChanging Scene in Analytical Chemistry,”by G. W. C. Milner.The Boots Co. Ltd., Lecture Theatre, Re-search, Pennyfoot Street, Nottingham.Informal Dinner at 7.30 p.m.George Hotel, George Street, Nottingham.MARCHThursday, llth, 10.30 a.m. : Nottingham Tuesday, 2nd, 4.15 p.m. : LoughboroughMidlands Region, jointly with the Laugh-borough University of Technology.“Immobilised Enzymes as Industrial Cata-lysts for Production and Analysis,” byAnalytical Division on “Legal Limits and theAnalyst. ’ ’The Boots Co. Ltd., Lecture Theatre, Re-search, Pennyfoot Street, Nottingham.S. A. Barker.Room J/OO/l, Edward Herbert Building,University of Technology, Loughborough. [continued inside back coverPrinted by Heffers Printers Ltd Cambridge Englan

ISSN:0306-1396    

DOI:10.1039/AD97613BX007

出版商:RSC    

年代:1976

数据来源: RSC

摘要:

Vol. 13 No. 2 Proceedings February 1976 of the Analytical Division of the C hem ica I Society CS Autumn Meeting Reading, September ‘I 975 At the Autumn Meeting of thc Chemical Society, held on September 25th, 1975, the Analytical Division, in conjunction with the Education Division, held a symposium on “Recent Trends in Education in Analytical Chemistry,” a t which 13 papers were presented covering both the schools/undergraduate inter- face, and also postgraduate courses in analytical chemistry.The morning session, under the chairmanship of Dr. J . B. Headridge (University of Sheffield) was opened by Dr. J . A. W. Dslziel (Chelsea College), who surveyed the teaching of analytical chemistry in the past, a t present and in the future. For iuture years he proposed that prospective post- graduate-equivalent students should be en- couraged to spend a period of about 2 years in industry or in Government service before returning to university for either part-time or full-time studies leading to a professional qualification.This procedure would increase their maturity and sense of personal responsi- bility as practising analytical chemists. During the subsequent period of discussion a number of opinions as to the length of the undergraduate and postgraduate courses (3, 4 or 6 years) were advanced, particularly in the light of current developments in other European countries.Then followed two papers by J . N. Lazonby (University of York) and B. A. Henman (RIC), covering the attitudes of schoolchildren to the study of chemistry.In both instances the results of pilot surveys only were reported, but these showed that many children had a strong interest in the subject. The preliminary findings of the York study indicate that there is not a significant swing from chemistry during the sixth-form course, which would suggest that the majority of sixth-form chemists who decide not to proceed to chemistry courses a t tertiary level have reached this decision before starting their sixth-form course.It was hoped that additional information would be forthcoming from more extensive surveys to be conducted in the coming months. The Nuffield syllabus was then discussed by M. Vokins (University of Bristol) and changes in the practical work carried out in schools over the last few years were stressed.Qualitative group analysis schemes had virtually disappeared in favour of more physical experiments such as relative molecular mass determination, thermochemical reactions, pH measurements, etc., in response to the wishes of schoolteachers for a closer relation between theory and practical work. B. J. Holland (Materials Quality Assurance Directorate, Ministry of Defence) then described the problems of an employer recruiting school leavers and graduates for work in chemical laboratories. In many instances basic chemical knowledge and practical skills were lacking. Many candidates were ignorant of simple classical tests such as those used for the detec- tion of chloride or sulphate.It was suggested that with present trends the career prospects for analysts who fail to secure adequate quali- fications were bleak indeed.The morning session was completed with papers from two speakers, Dr. R. A. Chalmers and Dr. I. L. Marr, from the University of Aberdeen. Dr. Chalmers emphasised that chemistry could be taught through the medium of analytical chemistry just as easily as through other branches. Some examples from his own course involving the analysis of alloys were given, in which theoretical matter was linked to industrial practice and costing questions. He stressed the need to upgrade the status of analytical chemistry in the universities, particu- larly through the creation of more Chairs.Dr. Marr described the practical course for under- graduates a t Aberdeen and indicated how the 3536 CS AUTUMN future employment of graduates was considered when designing practical work in the laboratory.In the afternoon, under the chairmanship of Professor G. W. Fowles (University of Reading) the postgraduate education of chemists was considered in detail. Professor D. Thorburn Burns began by surveying previous work on numbers of science graduates taking post- graduate courses.While there was a strong downward trend in postgraduate chemistry students in general, this was not the case in analytical chemistry where numbers of both students and staff had remained static. The Education and Training Group were a t present evaluating the returns from a survey carried out earlier in the year. This was a repeat of the survey of 5 years ago, the results of which were published in PYoceedings (1972, 9, 173).Of chemical publications, 65yo were in the field of analytical chemistry. Mr. Sandbach (CNAA) then explained how his organisation operated and the considerations that were important prior to approval of degree courses, for example, syllabus, facilities, staff qualifications and staff/student ratio. Out of 13 BSc schemes in polytechnics, 12 contained an analytical chemistry option in the final year.Dr. Harrison, although he had recently retired from the British Steel Corporation, described the requircrnents and attitudes of his own industry. Particular problems encountered were caused by the necessity for rapid rcsults for control of production lines and shift working. Although a range of academic study and attainments was involved, the ovcr-all emphasis lay in recruitment direct from school and part- time release for local Technicians, ONC and HNC courscs in chemistry, followed by the LRIC or even GRIC, in some instances.Mr. R. Sinar then discussed the importance of the MChcmA qualification to the Public Analyst Service. The syllabus had recently been revised and he hoped that more candidates from the Government Laboratory would present themselves for examination.Although experi- ence in a Public Analyst’s laboratory was an excellent preparation for the examination, it was by no means the only experience that would be appropriate. The statutory duties of the Public Analyst under the Food and Drugs Act must be taken account of in any examina- tion syllabus and this fact featured in the discussion that followed the paper.Dr. D. B. Horn (Western General Hospital, Edinburgh) discussed postgraduate training for clinical chemists. He outlined how the various uni- versity MSc and PhD courses were available MEETING PYOC. Amalyt. Div. Chcrn. SOC. to a restricted number of graduates, and discussed apprenticeship-typc training con- sisting of courses of lectures organised on a local basis and supplemented by six 1-week training courses organised by the Association of Clinical Biochemists, leading to the MCB or MRC Path.He explained how the current MCB qualifica- tion has resulted from the joint discussions of the Royal Institute of Chemistry, the Royal College of Pathologists, the Royal College of Physicians and the Association of Clinical Biochemists. During the first 3 years, the candidate works in an approvecl training laboratory beforc attempting the Part I examination, success in which leads to the award of a Diploma in Clinical Biochemistry.After a further minimum training period of 2 years he can sit the Part I1 examination, designed to assess the candidate’s maturity, his contribution to laboratory medicine and whether he is capable of taking independent charge of a clinical chemistry laboratory.Dr. Rettericlge then presented an amusing paper entitled “Should Albert Woods be Encouraged to Study for a PhD in Analytical Chemistry ? ” He argued that on economic grounds alone analytical research in the uni- versities was worthwhile, and illustrated the point with several examples of the major economic impact of various research projects.He felt that present PhD programmes provided a very good training for a chemist and to date such students had had no difficulty in finding employment as a soundly grounded scientist. The day’s proceedings finished with a dis- cussion led by a panel consisting of Dr. R. Denney (Thames Polytechnic), Dr. G. Nickless (Bristol IJniversity), Dr. J. G. Pritchard (NH London Polytechnic) and Dr. A. Townshencl (Univcrsity of Birmingham), and chaired by Mr. J . K. Foreman (Deputy Government Chemist). The Chairman began by introducing the panel and asking them to speak for a few minutes only, on special aspects of their own MSc courses. The discussion continued for nearly an hour, a t the end of a long day when most other Divisions had already completed their programme. Questions asked ranged from the relevance of MSc courses to an industrialist employer to the ease of obtaining financial support and to employment prospects a t the end of the course. It was agreed that the meeting had been useful, stimulating and informative even if some questions remained unanswered a t the end of the day. N. T. CROSBY

ISSN:0306-1396    

DOI:10.1039/AD9761300035

出版商:RSC    

年代:1976

数据来源: RSC

摘要:

REPORTS OF MEETINGS 37 Reports of Meetings Microchemical Methods Group The thirty-second Annual General Meeting of the Group was held a t 6.30 p.m. on Friday, December 5th, 1975, a t the Koyal School of Mines, London, S.W.7. The Chair was taken by the Vice-chairman of the Group, Dr. D. A. Pantony. The following office bearers were elected for the forthcoming year : Chaivwzan- Mr. R. Sawyer. Vice-Chaivvnan-Mrs.D. But- terworth. Honovavy Secvetavy-Mr. P. 11. W. Baker, Chemical Research Laboratory, Well- come Research Laboratories, Langley Court, Beckenham, Kent, B113 3BS. Honovavy Tveas- uvev-Mr. A. C. Thomas. Honovavy Assistant Secvetavy-Mr. B. T. Saunderson. iWembevs of Comwzittee--Mr G. C. Dickson, Dr. M. A. Leonard, Dr. D. Mowthorpe, Dr. D. A. Pantony, Dr. M.Thompson and Mr. C. A. Watson. Mr. H. Childs and Mr. H. I. Shalgosky were re- appointed as Honorary Auditors. Special Techniques and Atomic Spectroscopy G roups The thirty-first Annual General Meeting of the Special Techniques Group was held a t 2.30 p.m. on Tuesday, December 2nd, 1975, a t the Labora- tory of the Government Chemist, Stamford Street, London, SE1 9NQ. The Chair was taken38 REPORTS O F by the Cliairrnan of tlie Group, Dr.R. M. Llagnall. The following office bearers were elected for the forthcoming year : Cliazvman- Dr. P. B. Smith. Vice-Cliaivwzan-Dr. T. B. Pierce. Honovavy Secvetavy and Tveaswer- Mr. J. T. Davies, Research and Development Department, Metal Box Ltd., ‘Twyford Abbey Road, Park lioyal, London, N.TT. 10. ilfembevs of Coin?~zittee-Llr.I). H. Christopher, Mr. J . H. Glover, Dr. H. Hughes, Mr. P. Hurley, Dr. R. P. Mounce and Mr. L. Ruddle. Dr. G. Duff and Dr. J . Miller were appointed as Honorary Auditors . The Annual General Meeting was followed by a Joint Meeting with the Atomic Spectro- scopy Group at which the following papers were presented and discussed : “Some Analytical I’roblenis with Biological Samples,” by I<. h3.Dagnall; “Critical Factors in Spectrochcmical Analysis,” hy TV. Ramstlcn. Biological Methods Group The thirty-first Annual General Meeting of the Group was held at 6.30 p.m. on Thursday, November 27th, 1975, at the King’s Arms, 77 Buckingham Palace Road, London, S.W. 1 . The Chair was taken by the Chairman of the Group, Mr. F . W. Webb. The following office bearers were elected for the forthcoming year: Chaiviqzan---Mr.F’. W. Webb. Vice-Chaivman -Dr. J. A. Holgate. ITonovavy Secvetuvy- Mr. V. J. Hirkinshaw, Product Registration, The Boots Company Ltd., E.28 Thoresby Street, Xottingham, NG2 3AA. Honovavy Tveasuvev-Mr. D. J. X. Hossack. Nonovavy A ssistant Secvetavy--Miss F. K. Mulholland. Menzbevs of Cowzmittee-Miss A. Jones, Ur.L.. Singleton, Dr. M. W. Parkes and Ilr. B. A. Wills. Mr. 1). M. Freeland and Dr. J . H. Hamence were re-appointed as Honorary Auditors. The Annual General Meeting was followed by a Discussion Meeting at which a discussion on “Body Fluids and Crime Investigations,” was introduced by C. J. Price. This was followed by a Cheese and Wine Party. Automatic Methods Group The tenth Annual General Meeting of the Group was held at 2 p.m.on Thursday, December 4th, 1975, at the Laboratory of the Government Chemist, Stamford Street, London, SEl 9NQ. The Chair was taken by the Chairman of the ME ETI N G S PYOC. Amlyt. Div. Chem. Sor. Group, Mr. C. L. Denton. The following office bearers were elected for the forthcoming year : Chaivman-Mr. D. C. M. Squirrell. Vice- Chaivwzaw-Mr.J. L. Martin. Honovavy Secre- tavy-Dr. P. B. Stockwell, Laboratory of the Government Chemist, Cornwall House, Stam- ford Street, London, SE 1 9NQ. Ilonovavy Tveasuvev--Mr. K. H. Wall. Honovavy Assistant Secretary-Mr. D. G. Porter. Afembers of Committee-Mr. C. L. Denton, Dr. B. Fleet, Mr. S. Hill, Mr. J . Stevens and Mr. K. Swann. Dr. J. E. Page and Mr. IFr. H. C. Shaw were re-appointed as Honorary Auditors.The Annual General Meeting was followed by a Joint Meeting with the Education and Training Group, at which the Chair was taken by the Government Chemist, Dr. H. Egan. The subject of the meeting was “Training for Instru- mentation and Automatic Equipment” and thc following papers were presented and discusscd : “A4utoniatic Analvsis : I’roblenis in Training and Communications,” by L).C. M. Squirrel1 ; “The Technicon Approach to Training,” by I;. I-. Hooley ; “Training in a Clinical I,aboratory, ” by D. M. Browning. Electroanalytical Group The sixth Annual General Meeting of the Group was held at 6.45 p.m. on Friday, December 5th, 1975, in the Department of Metallurgy, lioyal School of Mines, London, S.TT.7. The Chair was taken by the Chairman of the Group, Mr.A. E. Bottom. The following office bearers were elected for the forthcoming year: Chairman- Mr. A. E. Bottom. Vice-Chaivman-Dr. TV. F. Smyth. Honovavy Secvetavji-Dr. U. J . Birch, Port Sunlight Laboratory, Unilever Ltd., Port Sunlight, Wirral, Merseyside, L62 4XN. Honovavy Tveasuver-Llr. A. G. Fogg. Honorary Assistant Secvetavy -Dr. A.G. Fogg. Members of Committee-Mr. I. E. Davidson. Dr. B. Fleet, Dr. I<. D. Jee, Dr. 1’. 0. Kane, n r . J . D. R. Thomas and Dr. H. Thompson. Dr. J . A. W. Tlalziel and Mr. J . H. Glover were re-appointed as Honorary Auditors. The Annual General Meeting was preceded a t 2 p.m. by an Ordinary Meeting of the Group which was held at Chelsea College, London, S.W.3. The subject of the meeting was “Polaro- graphy in the Life Sciences” and the following papers were presented and discussed : “Polaro- graphy in the Study of Metabolic Reactions,]’ by W.F. Smyth ; “Applications of Voltammetry to the Study of the Environmental ChemistryFcbmavy, 1976 REPORTS OF MEETINGS 39 of Metals,” by M. J. Stiff; “Electroanalysis of Toxic Metals in Blood and IJrine,” by A.A. Cernik; “L% Polarographic Study of Some Thioaniides of Pharmaceutical Importance,” by I. E. navidson; “Electroanalysis of Agro- chemicals in Crop Residues and Formulations,’’ by R. R. Rowe; “Kecent Applications of Voltammetry to Medicine,” by B. Z. Chowdhry. Education and Training Group The fifth _\nnual General Meeting of the Group was held a t 2.15 p.m. on Thursday, December 4th, 1973, a t the Laboratory of the Government Cliemi\t, Stamford Street, London, SE1 9NQ.The Chair was taken by the Vice-Chairman of the GI-oup, Profcssor D. Thorburn Burns. The following office bearers were elected for the forthcoming year : Clzaivman-T)r. J . H . Head- ridge. T’ice-Chazvmavz-Professor D. Thorburn Burns. Nunwavy Secvetavy-Dr. N. T. Crosby, Laboratory of the Government Chemist, Corn- wall House, Stamford Street, London, SE1 9NQ.Tlonovagl Tveasuvev-Dr. J . G. Pritchard. ?Jlenihevs of Conamittee-Mrs. M. I. Arnold, Dr. C;. S. llavy, Mr. H. Finlay, Dr. J . Parsonage, Mr. J . I). Wheatley and Dr. W. J . Williams. Mr. J . Rassett and Dr. J . A. W. Dalzicl were re-appointed as Honorary Auditors. The -\nnual General Meeting was followed by a Joint Meeting with the Automatic Methods Group as reported above.Atomic Spectroscopy Group The eleventh Annual General Meeting of the Group was held a t 2.15 p.m. on Tuesday, December 2nd, 1975, a t the Laboratory of the Government Chemist, Stamford Street, London, SE1 9SQ. The Chair was taken by the Chair- man of the Group, Dr. R. Smith. The following office bearers were elected for the forthcoming year: Chairman-Dr.R. Smith. Vice-Chaiv- wzan--J!Ir. C. P. Cole. Honovavy Secvetavy- Mr. D. J. Willis, Rank Hilger Ltd., Westwood, Margate, Kent. Honovavy Tveasuvev-Dr. G. B. Marshall. Honovavy A ssistant Secvetavy-Dr . W. J . Price. Members of Committee-Dr. E. J. Newman, Dr. Id. Ranson, Dr. B. L. Sharp, Dr. A. E. Smith, Mr. C. A. Watson and Mr. J . F. Woolley.Mr. D. Moore and Mr. 13. A. White were re-appointed as Honorary Auditors. The Annual General Meeting was followed by a Joint Meeting with the Special Techniques Group as reported above. The Annual General Meeting was also the venue for the first presentation of the Rank Hilger Spectroscopy Prize, which is to be awarded annually to a young spectroscopist for his contribution t o the practice of atomic spectroscopy.The prize was inaugurated in order to mark the Centenary of the Society for Analytical Chemistry and the Centenary of Hilger and Watts, and the 1975 prize was presented to Dr. B. L. Sharp by Mr. W. Ramsden, General Manager of Rank Hilger. Pvesentation of the pvize by MY. W . R a m s d e n to Dr. B. L . Sharp (L). The award was made for Dr. Sharp’s work on the application of lasers to atomic spectro- scopy and a summary of his recent lecture on this topic, given a t the Third Reports on Analytical Atomic Spectroscopy Symposium, immediately follows this report.Dr. Sharp carried out his postgraduate studies in analytical chemistry under Professor T. S. West and Dr. R. M. Dagnall at Imperial College, after obtaining a First-class Joint Honours degree in Chemistry and Physics from Lanchester Polytechnic. Initially, his post- graduate research concerned microwave plasma- emission spectrometry and photon-counting techniques, but, after the award of his PhD, he obtained SRC sponsorship for the study of laser-excited atomic-fluorescence spectrometry. His recent appointment to the staff of the Macaulay Institute for Soil Research, Aberdeen, will provide ample opportunity for research into the application of laser and plasma spectro- metry to agricultural and soil science.

ISSN:0306-1396    

DOI:10.1039/AD976130037b

出版商:RSC    

年代:1976

数据来源: RSC

摘要:

40 ANALYTICAL ATOMIC SPECTROSCOPY PYOC. Analyt. Div. Chenz. SOC. Analytical Atomic Spectroscopy Symposium The following is a summary of one of the papers presented at the Third Reports on Analytical Atomic Spectroscopy Symposium organised by the Atomic Spectroscopy Group and the Editorial Board of ARAAS, jointly with the Modern Methods of Analysis Group of the Sheffield Metallurgical and Engineering Association, and held on January Sth, I 975.Excitation Sources for Atomic Spectroscopy B. L. Sharp The Mncaulay Institute fov Soil Reseavch, Cvaigiebucklev, A berdeex, A I39 2QJ Potentially the most important optical excitation source developed in the last decade is the tunable laser. One of its obvious applications is in the area of atomic fluorescence, in which the particular benefits of laser excitation are associated with the ability of the source to saturate the excited state of a spectral transition.Saturation Spectroscopy Con- sider the rate balance equation for the population of a simple two-level atomic system in equilibrium A simplified theory is instructive in considering the benefits of attaining saturation. 'Z140 + n.lJ%oWv) + +z1z1g * ( 1 ) noZo1 -t ~ZoU(v)Bo, = quenching collisional absorption spontaneous stiniulated excitation emission emission where no and fll are the population densities of the ground and excited state, respectively; A,,, B,,, B,, are the Einstein transition probabilities; Zol, Z,, are the collisional transition probabilities; and U(v) is the energy density of the radiation field at frequency v .Rearranging equation 1 and ignoring collisional excitation, then With normal sources, U(v) is low, therefore nl/n, is low and no can be approximated by the analytical concentration N,. Thus, rearranging equation 2, replacing Z,, by the fraction of signal lost by quenching (+) and noting that the fluorescence is equal to the spontaneous emission we obtain . . . . - * (3) BF = N,U(v)Bo,+ * * . .which expresses the normal condition that in the absence of self-absorption the fluorescence yield, B,, is directly proportional to the concentration, the source radiance, the inherent line strength and the degree of quenching. With laser sources U(v) can be very large and hence as U(v) -+ co, %,/no -+ 1 and equation 2 is applicable. (a) Limiting sensitivity is reached because nl is maximised and the fluorescence output is regulated with respect to the source power. ( b ) The net power loss from the beam (-dP) is given by -dP = hv[n,B,,U(v) - n1Bl0U(v)].Now B,, = R,, (assuming the statistical weights, go, g, are equal) and, therefore, as nl -+ no, -dP -+ 0 so that no further net absorption occurs. Similarly, virtually no net absorption of the fluoresced photons occurs, so that self-absorption is minimised and an increased linear range of the growth curve is obtained.At high radiation densities the stimulated emission term U(v)Blo far outweighs the quenching term (Z,,) in equation 2 and therefore the relative effect of quenching is substantially reduced when compared with its effect on fluorescence signals obtained with thermal excitation sources.The consequences of attaining saturation are : (c)Feiimavy, 1976 ANALYTICAL ATOMIC SPECTROSCOPY 41 Calculation of Laser Power Required to Produce Saturation Actual calculation of the power required to saturate an excited state requires detailed consideration of the emission line shape, absorption profile and homogeneity of the target atoms.In summary, the power required to saturate the sodium D, (32Sl,2 +.32ql,2; 589.592 nm) transition was calculated for the instances of a homogeneous line,2 a line in which the velocity profile was considered to be inhomogeneous but the collisional profile homogeneous and a completely inhomogeneous line. The results of such calculations for the second instance are given in Fig.1 for sodium atoms in argon and nitrogen at 573 K (note qzl/NT is plotted, which limits at 0.5). Detailed calculations will be published e1sewhere.l I- < c 0 1 2 3 4 5 Log (P/w cmL ’! Fig. 1 . Theoretical plot of ~z,/h~~ vemus power for homogeneous Lorentz and inhomogeneous Dopp- ler profile for the sodium 589.592-nm line. In argon, the graph shows that a power density of 100-1000 W cm-2 should produce high saturation levels.The quenching effect of nitrogen is shown quite clearly together with the predicted outcome that the relative effect of a quenching species is gradually decreased as the saturation condition is approached. Experimental and Results A tunable dye laser (Electrophotonics, Model 23, output band width a t 589.592 nm about 0.19 cm-l) was used to excite sodium atoms contained in a furnace with argon a t atmospheric pressure.Ideally, the whole “viewing volume” should be irradiated in order to observe the saturation phenomenon under optimum con- ditions. In practice, focusing was required t o obtain higher power densities, measured as described elsewhere,l and therefore care was taken in selecting the viewing volume so as to minimise both pre-filter and self-absorption effects.The results obtained are shown in Fig. 3, the essential observation being that no evidence of saturation was obtained below about 3 MW cm-2, which is three to four orders of magnitude above the power predicted. The increased curvature at higher atom number densities is probably due to photon trapping causing increased power density in the viewing volume.Fluorescence experiments with a sodium-vapour lamp showed that the furnace yielded an increased concentration of sodium atoms with increase in temperature, but that the increase was not in accordance with the vapour-pressure curve. Laser excitation of the 589.592-nm transition produced no measurable fluorescence at the 588.995-nm line and vice zleysa. This is in contrast to classical experiments in which the intensity of the lines occur, as expected, in the ratio of their g values, i.e., 4:2.Further, the fluorescence at 589.592 nm was polarised in the laser plane, to different degrees in different directions, being highly polarised when viewed just off the laser axis. Experiments with conventional sources show the fluorescence of the 589.592-nm line to be unpolarised under all conditions.The experimental system is shown in Fig. 2.42 ANALYTICAL ATOMIC SPECTROSCOPY PYOC. Amxlyt. Div. Che?ii. s o c . Pin hole 4.0 i r/' 400"c Monochromator r l tt- H.F. +I Oscilloscope 3.0 I J 200 "c 1.4 2.8 4.2 5.6 1 .o 0 3 Power / MW cm-* 0 filter Fig. 3. Fluorescence (B,) of sodium Z'PI/SUS Fig. 2.Schematic diagram of instrument power density in argon gas at various system. temperatures. Discussion An explanation for the discrepancy between the calculated and experimental results could be because the laser is treated in the theory as an intense but essentially thermal source. A narrow-line, single transverse mode laser approximates to a diff raction-limited plane-wave generator and under certain conditions the coherence of the photon train radically alters the atom - radiation interaction. In 1954 Dicke3 showed theoretically that groups of atoms or molecules in constant phase relation with each other could interact and spontaneously emit coherent radiation.The number of centres combining was called the co-operation number (N,) and the effect is to multiply the spontaneous emission probability ( A ) by i N c , thus producing an enhanced value (A*).The radiation power from such excited states could be orders of magnitude above that from thermally excited levels and hence Dicke termed the emission super- radiance. This is to be distinguished from stimulated emission and the so-called super- radiant laser, which in fact depends for its operation on amplified spontaneous emission. Indeed, in the superradiance phenomenon the ground state of the transition, if suitably phased, has an equally important role to that of the excited state. Arecchi and Courtens4 have shown that there is an upper limit to N c , because after the spontaneous emission of the first photon, only those centres reached by this photon within the enhanced decay period (i.e., those within a distance of c/A*) can co-operate.Under our experimental conditions the value of N , would be approximately 2.6 x lo4, which gives an enhancement of the spontaneous emission rate by 6.5 x lo3 times. Other properties of superradiant emission are as follows. Supcrradiant photons are coherent and, therefore, the amplitudes, A , of their electric vectors are additive.Thus the power output, P, is proportional to ( 5.Ai>, which is proportional to NC2A2. That is, the emission is proportional to the square of the atom number density rather than being linearly proportional as in conventional fluorescence. The phenomenon is one of spontaneous emission and therefore causes a decrease in the radiative lifetime of a given state, with a resulting increase in the natural half-width. The radiation is directional, i.e., anisotropic, 2 = 1Febmavy, 1976 ANALYTICAL ATOMIC SPECTROSCOPY 43 its spatial properties being dependent on the direction and polarisation of the source and on the geometry of the excited atomic cloud.The possibility therefore exists that superradiance could be influencing our results.Certainly the presence of superradiance would explain the high powers needed to obtain saturation. Substitution of the enhanced emission rate, A*, into the calculation of power density indicates that levels of about lo7 W cm-2 are necessary to produce population levels of 0.49 or over. Also, the lifetime of such a superradiant state is about 2.47 ps compared with a mean collision time of about 34 ps and therefore radiative decay occurs in times that are short compared with the time required for collisional mixing of states. Thus, an explana- tion of a lack of fluorescence from the adjacent 32P3/z level is available.The polarisation of the output flux is also inherently predictable from the general mechanism of superradiance. Following excitation by a photon, an atom retains the phase of that photon until a collision occurs.When a collision interrupts the phase of an atom, it is said to be a de-phasing collision and it is precisely this process which gives rise to collisional broadening and the Lorentzian line shape. A principal condition for superradiance is that the photon-induced excitation rates are high compared with the de-phasing rates.In a static model this corre- sponds to the source being able to produce significant pumping of the target atoms in a time that is short compared with the de-phasing time. By considering the rate equations for excitation and de-excitation of an excited state, an expression for the time required to raise the population to (1 - lie) of its limiting value, i.e., the pumping time, T ~ , was obtained.Thus, T~ = 1/(21a + l / ~ ) , where I is the photon flux (photonscm-2), (T is the absorption cross- section (cm2), and T is the effective lifetime of the excited state. Taking a value of 1 MW cm-2 for the exciting power and substituting the relevant values for sodium we obtain T~ = 0.05 ps. Thus it would appear that, because the pumping time is short compared with the de-phasing time (about 34 ps), the conditions for superradiance to occur are fulfilled.Analytical Implications of Superradiance Assuming that superradiant states can be excited, a mechanism is available for increasing the intensity of a spectral line by several orders of magnitude. However, this would be at the expense of a non-linear growth curve and at low values of N , the dependence of the signal on N 2 could obviate any sensitivity gains associated with increased line strength.The signal has directional and phase properties which should enable good signal to noise ratios to be obtained in its measurement, and perhaps even allow the use of heterodyne techniques. Adversely, the broader spectral width of superradiant lines would hinder spectral discrimina- tion against background radiation.A further consequence of the presence of superradiance is that it makes realisation of saturation and its benefits more difficult. As with all natural phenomena, it has both potential advantages and disadvantages for the would-be user. Conclusions The experimental evidence available does not allow a definite confirmation of the exact interaction that is likely to occur between a laser and target atoms under typical analytical conditions. In our experiments saturation has not been fully achieved and there are indications that coherent excitation phenomena are playing an important part in deter- mining the results.It is important, therefore, that lasers should not be considered simply as very intense thermal sources, as erroneous predictions may result if this is assumed. Superradiance has been presented here as a theoretical possibility, but Dicke points out that the free induction decay of nuclear-spin states, observed in pulsed nuclear magnetic resonance spectroscopy experiments, is an example of superradiance. Thus the process considered is not entirely unknown; it is only its extension to another part of the electro- magnetic spectrum. References 1 . Sharp, B. L., and Goldwasser, A., Spectvochim. Acta, B , submitted for publication. 2 . Hercher, M., A p p l . Opt., 1967, 6, 947. 3. Dicke, K. H., Phys. Rev., 1954, 93, 99. 4. _4recchi, F. T., and Courtens, E., Phys. Rev., A , 1970, 2, 1730.

ISSN:0306-1396    

DOI:10.1039/AD9761300040

出版商:RSC    

年代:1976

数据来源: RSC

摘要:

44 ANALYSIS OF IXDUSTRIAL EFFLUENTS PYOC. Analyt. Din. Chenz. SOC. Applications of Analytical Techniques to industrial Effluents The following are summaries of two of the papers presented at a Joint Meeting of the East Anglia Region with the Eastern Region of the CS Industrial Division held on October 23nd, 1975, and reported in the November issue of Pyoceedings (p. 285). Organic Carbon and Oxygen Demand Analyses and Their Relationships in Waste Waters and Effluents G.F. Lowden Watei. Reseavch Centre, Stevenage Laboratovy, Eldev W a y , Stevenage, Herts., SG1 1 T H In pollution control, the presence of organic matter is a reasonable indication of pollution. Organic matter can be determined either by measuring the total organic carbon (TOC) directly or by measuring the oxygen consumed during oxidation.Methods for measuring oxygen consumption include tests for permanganate value (PV) , biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total oxygen demand (TOD). The PV1y2 is the simplest and cheapest chemical test, involving mild oxidation with acid permanganate for 4 h at 27 "C. This gives only an approximate estimate of the oxidisability of a waste.The BOD1-3 is a biochemical test in which the waste is diluted with water saturated with oxygen and containing nutrients and bacteria. The dissolved oxygen is measured before and after incubation for 5 d at 20 "C. Nitrification4 is an unpredictable reaction that is usually suppressed in the BOD test by the addition of allylthio~rea.~ The test is time consuming, and the introduction of an electrode for determining the dissolved oxygen has helped only marginally.The COD2Y6 is a chemical test in which the waste is oxidised by refluxing for 2 1-1 with a sulpliuric acid - potassium dichromate mixture. Ammonia, however, is not oxidised and therefore organonitrogen compounds are never fully determined. Automated versions of this test are available.'-9 A sample is injected into a catalytic furnace at 900 "C, giving virtually complete oxidation of both carbon and nitrogen compounds.Oxygen consumed during combustion is measured electrically. Unfortunately, the oxidation of ammonia can be erratic1" and the presence of nitrates, which donate oxygen, can give misleading results. The TOC14-22 gives an absolute value for carbon by an instrumental method similar to the TOD but it is cheaper and less affected by interferences. After oxidation, the carbon dioxide produced is either measured by infrared spectrometry or is reduced pyrolytically to methane and measured with a flame-ionisation detector.Most instruments determine the organic carbon after pie-treatment to remove inorganic carbon, which can lead to a loss of volatile compounds. Some instrumentsz0 are designed to overcome this disadvantage, and include the volatile fraction in the TOC result.Possibly the easiest and cheapest way of monitoring organic matter is to use a submersible flow cell utilising absorbance in the ultraviolet region at 204 nm to measure the TOC.'4321 The BOD will indicate how much oxygen will be used up biochemically and is the only test to indicate biodegradability.I t will not indicate the concentration of organic matter actually present unless it is all biodegradable. This concentration is better determined by the COD, which will measure the undegradable and the biodegradable organic matter. However, it will not differentiate between organic and inorganic oxidisable matter, nor will it give a true valuc for oxidisable nitrogen compounds.This is achieved by the TOD, which gives a result similar to the COD plus any oxygen consumed by oxidisable nitrogen compounds. The TOC gives the concentration of organic carbon but no indication of the oxidation state. Numerically, the TOD is usually slightly greater than the COD and is very much greater if a high proportion is nitrogenous material.The COD is always greater than the BOD and the TOC. In a domestic sewage, the ROD is usually higher than the TOC but in the effluent from The TOD is an instrumental method1°-13 that provides a result in 5 min.FcbrLcavy, 1976 ANALYSIS OF INDUSTRIAL EFFLUENTS 45 treatment of sewage the opposite occurs because undegraded material remaining in the effluent shows no BOD but still contains TOC.A similar situation exists with COD and BOD, in that the COD to BOD ratio increases in proportion to the undegraded material present. Ratios of the COD or TOD to TOC are usually very steady. Any increase in the TOD to COD ratio would indicate the presence of nitrogenous compounds while a decrease may indicate the presence of nitrates such as occur in well treated effluents.Correlations are more fully discussed in references 11, 12, 14, 23 and 24. 1. 3 4. 3. 4. 5. A. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 2 2 . 23. 24. c References Department of the Environment, “Analysis of Raw, Potable and Waste Waters,” HRI Stationery Office, London, 1972. ,.\merican Public Health Association, American Water Works Association and Water Pollution Control Federation, “Standard Methods for the Examination of Water and Waste Mrater,” Thirteenth Edition, American Public Health Association, New Work, 1971.Clark, D. W., W a t . Sewage WAS, 1974, 121, 68. Water Pollution Research Laboratory. Nicolson, N. J., W a t Pollut. Control, 1974, 46, 621. Stones, T., Wat. Pollut. Covztvol, 1974, 46, 673.Jirka, A. M., and Carter, M. J., Analyt. Chem., 1975, 47, 1397. Geisler, C., Anclrews, J . F., and Schierjott, G., W a t . Wastes Engng, 1974, 11, 26. Technicon Instruments Co. Ltd., Houndmills, Hasingstoke, Hants. Musselwhite, C. C., Technical Memorandum TM 107, Water Research Centre, April, 1975. Goldstein, A. I,., Katz, W. E., Meller, F. H., and Murdoch, D.M., paper presented to the Division of Kavenscroft, B. D., paper presented to the Society for Analytical Chemistry, North East and Scottish Butzelaar, P. I?., and Hoogeveen, 1,. P. J . , Watev Sevv., 1975, 79 (948), 50. Briggs, R., Schofield, J. W., and Gorton, P., paper presented t o the Institute of Water Pollution Helms, J. W., US Department of the Interior, Geological Survey, Open File Report, 1970. van Hall, C.E., and Stenger, V. A., Analyt. Chem., 1967, 39, 503. Sovann, K., Process Engng, 1975, March, 56. Croll, B. T., Chemy I n d . , 1972, 386. Takahasi, Y., Moore, K. T., and Joyce, R. J., Am. 1-ab., 1972, 4, (July), 31. Oceanography International Corporation ; UK agents : Kontron Instruments Ltd., Broadwater Ogura, N., and I-Ianya, T., J . W a t .Pollut. Control Fed., 1968, 40, 464. Raker, C. D., Bartlett, P . D., Farr, I. S., and Williams, G. I., Frcshwat. Biol., 1974, 4, 467. IVood E. D., Perry, A. E., and Hitchcock, M. C., paper presented to the American Chemical Societj-, Stenger, V. A., and van Hall, C. E., ,J. LVat. Pollztt. Conti/ol Fed., 1968, 40, 1755. Notes on Water Pollution 50. 52, March, 1971. Water, Air and Waste Chemistry, American Chemical Society, New Jersey, September, 1968.Regions, and the Society for Water Treatment and Examination, Newcastle, February, 1975. Control, Southern Branch, Southampton IJniversity, January, 1975. Road, Welwyn Garden City, IIerts. Houston, Texas, February, 1970. Studies of Oils and Polycyclic Aromatic Hydrocarbons in Sewage-related Systems D. E. Caddy and D.M. Meek TVatev Rrseavch Ce$ttve, Stevenage Labovafovy, Eldev W a y , Stevenage, Hevts., SG1 1 T H Mineral Oils A method used at the Water Research Centre for the extraction of mineral oils from aqueous samples involves extraction with carbon tetrachloride in a continuous liquid - liquid extractor for 16 11. Oil in sludge is initially adsorbed on Celite, which is then extracted with carbon tetrachloride in a Soxhlet apparatus. After extraction, polar material is removed from the extracts by passage down a Florisil column.Final analysis is normally effected by measure- ment of the infrared C-H stretching absorbance at 2 926 cm-I. Absorptivities of oils vary considerably, and errors can occur if the nature of the oil is unknown. Hence the method iy commonly used in conjunction with gas-chromatographic characterisation of the oil so that an appropriate value for the infrared absorptivity can be used.For many sewage, sludge and effluent samples, however, the use of a single mean absorptivity does not cause undue error.46 ANALYSIS OF INDUSTRIAL EFFLUENTS Polycyclic Aromatic Hydrocarbons (PAHs) Proc. A.naZyt. Div. Chem. SOC.Many PAHs have been shown to be carcinogenic to mammals. They are produced as relatively stable intermediates in the biodegradation or thermal decomposition of other organic compounds, e.g., steroids, and are found in environmental samples such as oils, smokes and sewages. Current methods for the determination of PAHs tend to be either laborious or expensive. The present work is an attempt to determine some PAHs using a relatively simple technique employing inexpensive and readily available equipment.Gas chromatography was found to be the most efficient method of separation, and fluorimetry the most sensitive means of detecting eluted PAHs. It was shown that the responses of some PAHs at optimum wave- lengths for excitation and fluorescence could vary by a factor of at least 60, indicating that direct fluorescence measurements were inadequate.Samples were injected on to a glass column containing 50/, OV-1 or 5% Dexil on Chroiiiosorb W. The column eluate was split, 10% passing to a flame-ionisation detector and the re- mainder into a cooled stainless-steel tube into which cyclohexane was pumped through a concentric hypodermic tube (Fig. 1 ) .The resulting solution passed through a vertical side- arm to a glassT-junction where the carrier gas and some excess of solution were removed, and thence to a vertically mounted flow cell in a fluorimeter. The flow cell was square in cross- section (0.5-cm sides) and the fluorimeter used was a simple filter instrument. Samples were excited by an ultraviolet radiation band of 280-330 nm, and the fluorescence was measured at 350-450 nm.Signals from the fluorimeter and the flame-ionisation detector were displayed simultaneously on chart recorders. To flame-ionisation detector To fluorimeter flow cell Fig. 1 . Gas chromatograph - fluorimeter interface. Using this system, peaks were obtained for the following PAHs, in decreasing order of response: perylene, fluoranthene, benzo[ghi]perylene, benzo[n]pyrene, benzofluorene, benzochrysene, benzanthracene and pyrene.The response for these peaks was linear within the range studied when assessed by peak area. About l o n g of the compounds could be detected. For samples of 35-s central heating oil, peaks were tentatively ascribed to fluor- anthene, pyrene, benzofluorene, methylpyrene and benzophenanthrene. Fluoranthene was identified on two columns and was determined at 40mg1-1 Peak differentiation withFebmavy, 1976 ANALYTICAL TECHNIQUES USE11 I N INDUSTRY 47 lubricating oil samples was poor, showing an envelope of unresolved fluorescent material eluting with a maximum at a longer retention time than the maximum of the flame-ionisation detector trace.Activated-sludge extracts gave traces showing the presence of PAH material emerging towards the end of the run. The two major peaks had retention times very similar to those of niethylpyrene and benzochrysene. Using an interface of the type shown in Fig. 1, a gas chromatograpli could be combined with other types of spectrophotometric equipment, such as an AutoAnalyzer. Although the work is incomplete, and at this stage does not constitute an analytical pro- cedure, the technique described, perhaps with some modifications to the interface to reduce turbulence and dead-space effects, should form a feasible approach to the determination of T'AHs even in the presence of swamping concentrations of paraffinic and other non-fluorescent mat er i d .

ISSN:0306-1396    

DOI:10.1039/AD9761300044

出版商:RSC    

年代:1976

数据来源: RSC

摘要:

ANALYTICAL TECHNIQUES USE11 I N INDUSTRY 47 Analytical Techniques Used in Industry The CS Annual C,hemical Congress, with the central theme of “A View Towards the 21st Century,” was held at the University of York from April 7th to l l t h , 1975. The Analytical Division organised a Symposium entitled “Analytical Techniques Used in Industry” on April 9th and loth, and the following is a summary of one of the papers presented.Summaries of three of the other papers presented appeared in the August issue of Proceedings (p. 229). Analysis in the Electrical Industry H. J. Cluley The Geneva1 Electric Company Limited, Hirst Research Centre, Wembley, Middlesex The electrical industry is very diverse and heterogeneous in nature. Thus, the technologies and scale of operations of a nuclear power station are vastly different from those of the manufacture of semiconductor devices, in which hundreds of devices may be delineated on a small chip of silicon.Other parts of the industry, such as telecommunications, or cable making, or domestic equipment, are very different from both and from each other. The ramifications of lamp making have a distinctly chemical flavour, with operations such as glass making, extraction of tungsten from the ore for the filament and the use of species such as metallic sodium and halogens in various types of lamps.However, for the industry as a whole, chemistry is a minority interest and chemists are correspondingly thin on the ground. One consequence is that any distinction between the analytical and non-analytical chemist may be somewhat blurred.Moreover, the analyst in the electrical industry, unlike his equivalent in a chemically orientated industry, is providing a service not in the main for other chemists but for electrical engineers, mechanical engineers, physicists, etc. In so doing he tends to acquire a t least a smattering of the relevant technologies, and this may be very desirable for his intelligent contribution to the solution of the problems that these technologies create.In such ways the chemists and analysts, though small in number, have with other materials scientists a vital role to play in maintaining and increasing the technical health of the industry. The limited concern with chemistry within the electrical industry can create a need to house specialist analytical facilities centrally within an organisation.Our analytical facility at Hirst Research Centre falls into this category, and as problems that require analytical investigation come to us from throughout the Company, our analytical activities tend to reflect the diverse analytical needs of the industry as a whole. The following examples serve to illustrate problems arising in various parts of the industry, but also give some indication of the range of analytical techniques involved.Likewise, the impact of chemistry varies somewhat within the industry. Examples of Analytical Problems One recurrent requirement, common to many industries, is characterisation of unknown For in- materials such as those of other manufacturers that are bought-in components.48 Proc.Analyt. Div. Cheruz. Soc. organic materials X-ray fluorescence is often the preferred technique, particularly where non-destructive examination is required and where the incident X-radiation can be directed to different regions of a product in order to identify the individual materials. Thus, exami- nation of appropriate areas of a switch contact arm permits identification of the arm material and of any plated layers in the contact region.Electrical contacts evoke another general problem from various parts of the industry, that of identifying the cause when high resistances develop. This is a fruitful field for analysis in view of the variety of possible causes such as particulate contamination, condensa- tion from the vapour phase, polymer formation from gaseous organic species, and, of course, metal attack such as that of hydrogen sulphide on silver. For detection and identification of organic Contaminants in particular, pyrolysis - gas chromatography is a useful technique.Problems in this general category, namely, the contamination of functional surfaces, provide another recurrent analytical theme.One example, from the telecommunications part of the industry, concerned delay in operation, or even failure to operate, suffered by some relays in telephone exchanges. This was due to a minute but very sticky deposit that developed on a phosphor bronze stud, and which tended to “glue” the stud to the metal component that it contacted in relay operation. By infrared and other techniques the deposit was shown to comprise copper carboxylates. This led to a major exercise to establish which of the many plastics materials used was giving rise to the causative traces of carboxylic acid vapours in the enclosed exchange system.A gas-chromatographic method enabled the pattern of acids evolved from particular materials to be correlated with those present as copper salts in the deposits on relays.This problem illustrates another general theme, the need to study material transfer through the gas phase, and a further example is from the area of nuclear power. In the commissioning stage of gas-cooled reactors, the gas must be monitored, particularly for water and other potentially corrosive species that may be evolved from materials during the initial heating runs.This task, undertaken in the 1960s for Magnox reactors and due to arise again with AGR stations, is but one of many instances in which analysis must be done on-site instead of in the laboratory. Measurement of water, not only in gases but in diverse solids, liquids and sealed systems, is another common requirement in that even very low levels of water are often inimical to electrical systems.One example, from the cable-making part of the industry, concerns measurement of water in paper insulation in high-voltage cable. For determination of water in this and many other contexts, the electrolytic hygrometer is a convenient device. One example, in the production of thermionic valves, arises when beryllia is used to provide electrical insulation with good thermal conductivity.A spectrographic method, measuring down to a few nanograms of beryllium, is used to achieve the high sensitivity required for monitoring purposes. A key facility in this context is electron microscopy, particularly in the scanning mode. This frequently provides significant information on the physical texture of surfaces, as exemplified by a study of the effect of successive stages in a process for frosting lamp bulbs.Likewise, geometrical defects in semiconductor devices may be revealed, at magnifications necessarily beyond those of the optical microscope. The scanning electron microscope can also assist failure analysis of semiconductor devices by use of voltage-contrast effects in order to image operating parts of the circuitry, thereby assisting in locating a point of failure.The basic materials used in semiconductor devices (e.g., silicon, gallium, arsenide) and also diverse specialised materials used in other parts of the industry are required to be high- quality single crystals. This invokes the need to study the crystallographic perfection of such materials by use of the technique of X-ray diffraction topography. Regions of strain, associated with defects in a single crystal, can affect the intensity of diffracted X-radiation, and therefore this technique provides a mapping facility which distinguishes defects from regions of crystal perfection. Such studies, on single-crystal materials used in the semi- conductor, laser and communications parts of the industry, concern not only the as-grown crystals but also detection of any defects introduced in processing operations. One such example concerned the need for non-destructive measurement of the degree of deuteration ANALYTICAL TECHNIQUES USED IN INDUSTRY Monitoring of air or dust samples for toxic species is a not infrequent requirement.As previously mentioned, much analytical work concerns surface studies.Other applications of X-ray crystallographic techniques are often of value.Febvuwy , 1 Y 76 EQUIPMENT NEWS 49 of crystals of K(D,H),PO,, which can be used for laser switching. This problem was solved by use of an X-ray diffraction method for high-precision measurement of the a, lattice parameter of the crystals, which varies linearly with degree of deuteration.Future Trends Extrapolation of trends over the last decade or so may provide some guide to the future. Consider purity of materials : in the early days of semiconductors, germanium containing approximately 1 p.p.m. of arsenic was thought to be very pure, but our concepts of desirable maximum impurity levels have now descended by several orders of magnitude.This trend seems likely to continue, and the fact that a 0.001 p.p.m. impurity can represent l0l3 impurity atoms per cubic centimetre reminds us that absolute purity is still very distant. Continuing developments in mass and flame spectrometry and related techniques may be of help in arialysing purer and purer materials. Use of even purer materials may make them a more ready prey to Contamination, which necessitates consideration of material - material interactions, contamination from the gas phase, etc.Such problems, currently providing needs for analysis, may assume greater significance in future. The industry is much concerned with surfaces that emit electrons, or that emit, reflect or absorb radiation; also, devices and circuitry based on thin deposited films are becoming increasingly important.Such interests give rise to a concern for the chemical composition, cleanliness and physical texture of surfaces. With a likely yield of new information from developing techniques such as electron spectroscopy, a continuing and increasing concern with surface studies seems inevitable. One factor that is unlikely to disappear during this century is that of human frailty.Supply of incorrect materials, mistakes in material preparation, or use of materials or equip- ment under quite inappropriate conditions, can lead to consequences that the analyst is required to resolve. Such human errors seem likely to continue to furnish needs for analysis. In these and many other ways a continuing need for analysis in the industry seems likely, particularly if “analysis” is interpreted in a wide sense so as to include the characterisation of materials by a multi-disciplinary approach.But will there also be a need for analysts, or will they be replaced by computerised, automated equipment ? Happily, the analyst seems likely to survive for at least two reasons. Firstly, the variety of problems and materials concerned, often requiring difficult sampling operations and multi-disciplinary investigations, would seem to defy automation. Secondly, all the signs are that no all-purpose analytical machine will emerge and that the proliferation of individual analytical techniques will continue, so that at least the human intervention of the analyst will be required in order to decide what techniques are used first and how the results so obtained should be followed up. These and other reasons lead to the firm belief that in the foreseeable future the electrical industry will have a continuing need both for analysis and for the analyst.

ISSN:0306-1396    

DOI:10.1039/AD9761300047

出版商:RSC    

年代:1976

数据来源: RSC

摘要:

Febvuwy, 1976 EQUIPMENT NEWS 49 Equipment News Gas Chromatography Perkin-Elmer now have a system (PNA), for use with their F33 gas chromatograph, with which to separate saturatc>d hydrocarbons. 'The PhTA uses a molecular-sieve technique developed by British Petroleum rather than the con- ventional methods based on high-resolution open tubular columns. Instead of obtaining an inadequate separation o f individual com- ponents a group separation is carried out.Initially, total aromatics are obtained on a lox molecular sieve pre-column, which can then be backflushed. At the same time a type separa- tion of C, to C,, paraffins and naphthenes is carried out on a 13x analytical column. This method for PNA analysis (currently IP 321/75 Tentative) has been submitted to the Institute of Petroleum for consideration as a standard.Perkin Elmer Ltd., Post Office Lane, Beacons- field, Hucks., HP9 lQA. The range of the GCD Gas Chromatograph has been extended with the addition of Thermal Conductivity (TC) and Electron Capture (EC) versions. These are low-cost instruments for repetitive gas-chromatographic analyses. Both include the isothermal single-column oven50 EQUIPMENT NEWS PYOC.Analyt. Div. Chein. SOC. system and the separately heated injection and detection zones of the FID Model. The TC version utilises a constant filament temperature detector, which enhances the linear range ( lo4) and protects the filaments against damage from uncontrolled heating resulting from temporary loss of carrier gas. A detectability of 7.5 x In the EC model the single electron-capture detector incorporates a G3Ni radioactive source and operates in the pulse-modulated mode.With this system a linearity of up to lo4 may be achieved and a detection limit of 1 x g s-l of dieldrin is claimed. g ml-1 of toluene is claimed. Pye Unicam Ltd., York Street, Cambridge. Air Monitoring The J/IY MV2 “Sniffer” is a compact, light- weight, battery-operated mercury-in-air rnoni- tor.It has a retractable probe (305 mm) and gives clual-range readings. The higher range is suitable for locating sources of mercury vapour, the lower sensitivity, 0.01 mg mp3, is designed for toxicity studies (TLV,h for mercury vapour is 0.05 mg m-”. Shandon Southern Instruments Ltd., Camber- ley, Surrey. The Miran 101 is a portable, specific vapour analyser for vinyl chloride monomer.A built- in pump is used for ambient air sampling and direct readings in the ranges 0-25 and 0-250 p.p.m. can be obtained. It is said to be sufficiently selective, sensitive and robust for on-site measurement of potentially hazardous vinyl chloride vapours. Techmation Ltd., 55 Edgware Way, Edgware, Middx., HA8 8JP. The range of products from Infrared Industries, Inc.and the Environmental Products Division of the Whittaker Corporation is now available in the UK. The range includes instruments for the control of processes and ambient air quality and includes portable as well as large, completely automatic systems with facilities for single or multi-parameter measurements. Included in the range of gases that can be Irionitored are SO,, NO,, NO,, O,, CO, and H,S.TPC T - t d . , 134 SClLVA CCLSt KC%<, 17ext- haven, Sussex, BN9 8 J J . Total Oxygen Dernsnd and Total Carbon The Moclel 335 7‘011/TC measures h t l i total oxygen demand and total carbon in water. Samples are automatically injectxl into the combustion furnace and both nieasurements presented on a potentiometric recorder.The carrier gas is nitrogen, containing a fixed con- centration of oxygen, any oxidisable com- ponents being converted to their stable oxides on a platinum catalyst a t 900 “C. All carbon is converted to carbon dioxide, which is measured on an infrared analyser and portrayed as the first peak. The momentary depletion in the oxygen concentration in the carrier gas is detected by a fuel cell and is recorded as the second peak.For total (non-volatile) organic carbon, the samples are first acidified (with hydrochloric acid, as sulphuric and nitric acids interfere in the TOD test) and carbon dioxide is eliminated with nitrogen. In the low ranges the TOD full scale is 0-200 p.p.m. ancl the TC is 0-100p.p.m. A repeatability of &2-3% full scale is claimed.The cycle time for both measurements is 5 min. Techmation Ltd., S$ Edgware ITay, Edg- ware, Midds., HA8 SJP. Low-cost Spectrophotometers With the SP6 visible - ultraviolet series a new range of low-priced versatile spectrophoto- meters is now available. Controls are colour coded with analogue or digital display of linear transmittance, absorbance and concentration. Back-off facilities reduce the need for dilution or path-length change ancl permit monitoring of reactions with high initial absorbance.Cells from micro up to 40-mm path length can be accommodated. A wide range of sampling accessories is available and so is a teaching kit for educational establishments. A comprehensive dossier about the series and technical literature is available from Pye Unicam Ltd., Uork Street, Cambridge.X-ray Spectrometry The TXRF 24-element simultaneous X-ray spectrometer is built around the well estab- lished OEG 75 X-ray tube. The pulse-handling system is digital throughout and a goniometer is provided for qualitative or scmi-quantitative studies. Information on this, the “Betaprobe,” and other equipment in the Telsec range can be Qki- d11ILU : - -*-7 .c- I1 \>In - Lane West, Littlemore, Oxford, OX4 5JX.TCllSC:2 InstrumCllts L t A . , Smdy Automated Glucose and BUN Analysis The fully automated Systcm 1 Glucose/RUK Analyser, which combines into one compact bench-top instrument the capabilities of thcFcbruavy, 1976 CONFERENCES AND MEETINGS 51 Glucose and Blood Urea Nitrogen Analysers is announced. Discrete samples are used (up to 40 in the turntable), the sample volume is 14 p l per test with a throughput of 56 each of glucose and BUS per hour.There is also a facility for examining single samples for either com- ponent with a readout in 64 s. Glucose measure- ment is based on the rate of oxygen depletion in a glucose - oxidase reaction and BUS on the change in conductivity rate during a urease reaction. Beckman-RIIC Ltd., Eastfield Industrial Estate, Glenrothes, Fife, Scotland.All-purpose Transducer A multi-purpose transducer is announced, the L7iiimcasure/80, the main feature of which is the purely resistive output ( 100-500 0) readable on any ohmeter or multimeter without addi- tional electronics, A stability of better than 0.01 !2 is claimed with good accuracy and resolution.The principle is based on a semi- conductor chip the resistance of which changes with movement in a controlled permanent magnetic field. Adaptor attachments are avail- able for direct conversion of the transducer into a pressure or force sensing device. ID. Pitman Ltd., Jessamy Road, Wey- bridge, Surrey, KT13 8LE. Measurement of Liquid Flow A light, compact, portable flow meter for use in a wide variety of aqueous and organic liquids has been developed.The revolutions of a minute turbine spinning on a tungsten carbide - sapphire bearing are counted as precise pulses and recorded on a separate readout instru- ment. The basic transmitter is powered by 10-2OV d.c. An accuracy of &lyo for flow- rates of from 1 drop every 1 4 s to 20lmin-l is claimed and internal switches permit cali- brations to be made in various units.Litre Meter Limited, Ryefield Crescent, Northwood, Middx., HAG 1NX. New Chemicals A range of liquid scintillators and scintillation- grade chemicals is now available. These high- grade products have been developed to provide maximum efficiency in the counting of radio- isotopes when combustion techniques are used.Scintillator Division, Koch-Light Labora- tories Ltd., Colnbrook, ]Sucks. available. This material is porous, mechani- cally stable and for chromatography can be packed rapidly and uniformly to give stable, incompressible columns with high, reproducible flow-rates. For literature on uses, etc., write to BHD Chemicals Ltd., Poole, BH12 4". A new agarose chromatographic medium Sepharose CL has recently been introduced. This is a covalently crosslinked gel which permits gel-filtration studies in strongly de- naturing, organic or other harsh conditions a t temperatures over 80 "C in the range pH 3-14. For further information on this material and the Pharmacia PL4GE system for ultra-high resolution of macromolecular mixtures contact Pharmacia (Gt. Britain) Ltd., Paramount House, 75 Uxbriclge Road, London, W5 5SS. A new form of spheroidal hydroxylapatite developed by the AEKE at Harwell is now

ISSN:0306-1396    

DOI:10.1039/AD9761300049

出版商:RSC    

年代:1976

数据来源: RSC

摘要:

February, 1976 CONFERENCES AND MEETINGS 51 Conferences and Meetings Determination of Admixtures in Hardened Concrete Maych 18, 1976, Lo7.zdo72 A paper on this subject will be presented by Mr. li. Iiixoni of Joseph Crosfield Ltd. a t a meeting of the Road and Building Materials Group of tlie Society of Chemical Industry on March 18, 1976. The meeting is to be held a t the Society of Chemical Industry, 14 Belgrave Square, London, SWlX 8PS, and will begin at 6.00 p.ni., refreshments being available a t 5.30 p.m.Biological Applications of Mass Spectro- metry iWavch 23, 1976, Livevpool The Mass Spectroscopy Group is organising a one-day meeting on the above topic a t the TJniversity of Liverpool on March 23, 1976. The main theme will be the use of data pro- cessing and niass fragmentography in the analysis of biological extracts, with emphasis on the practical application of these techniques.Invited speakers are Professor E. Jelluni (Oslo), Dr. A. Lawson (London), llr. G. King (London) and Dr. N. A. B. Gray (Cambridge). In addition, tlie meeting is intended to en- courage discussion of these techniques and brief52 CONFERENCES AKD MEETINGS Yroc.Agzalvt. Div. Chcnz. SOC. contributions to the discussion periods will be n-elcomed. Further details from the Group Secretary, Dr. J . R. Chapman, AEI Scientific Apparatus Limited, Barton Dock ltoad, Urniston, Man- Chester, M31 2LD. Symposium on the Role of the Analytical Chemist in the Protection of Society- With Special Reference to Techniques’ Development and Application ;VIavch 25-26, 1976, Cantevbwy This Symposium, organised by the South East Region of the Analytical Division, will be held a t the University of Kent a t Canterbury.A Plenary Lecture will be given by J . I(. Foreman (Laboratory of the Government Chemist) and thc following papers will be pre- sented : “Packed-tube TrappingPA4 Technique for the Analysis of Traces of Vaporised I’esti- cides,” by A.1’. Woodbridge (Shell Iiesearch) ; “ Detection and Measurement of Flammable Gases,” by J . G. Firth (Health and Safety Executive) ; “Trace Organic Compounds in Sewage Effluents : Current Analytical Prob- lems,” by J . Gardiner (Water Kesearch Centre) ; “ Kadioactivity-Environmental Protection Cri- teria and Their Relation to Analytical Methodo- logy,” by J . W.R. Dutton (Ministry of Agri- culture, Fisheries and Food) ; “Electron Spectro- scopy, ” by D. Betteridge (University College of Swansea); “The Importance of Being Practical-With Reference t o the Work of the Analytical Methods Sub-Committee,” by L. E. Coles (County Public Health Laboratory, Cardiff) ; “Continuous Electrochemical Sensors for On-line Monitoring of Effluents,” by €3.Fleet (Imperial College) ; “The Testing of High-alumina Cement Concrete by Thermal Analysis,” by C. J. Keattch (Industrial and Laboratory Services); “The Use of High- performance Liquid Chromatography for Quality Control in the Pharmaceutical Industry,” by F. Bailey (ICI Pharmaceuticals Division) ; “Methods for the Determination of Vinyl Chloride Monomer in Various Media,” by J .T. Davies, M. C. Doe and P. J . Sausin (Metal Box Company) ; “Applications of MECA to the Determination of Compounds of Environmental Interest,” by A. Townshend (University of Birmingham) ; “Applications of Carbon Furnace Atomic-absorption Spectrometry in Environ- mental Analysis,” by J . M. Ottaway (University of Strathclyde) ; “Oil Pollution-Analysis and Source Identification,” by G.G. Jenkinson (Laboratory of the Government Chemist) ; “Analytical Techniques in the Control of Asbestos Dusts,” by J . L. Jarvis and A. A. Hodgson (Cape Asbestos Fibres Ltd.). Registration forms and information can be obtained from Miss P. E Hutchinson, The Secretary, Analytical Division, Chcmical Society, Burlington House, London, WlV OBN. Short Courses on Spectroscopy 1976, Lolzdolz The following short courses are to be held a t the Polytechnic of North London during 1976.Atomic *Absorption Spectroscopy, a 3-day full-time course, Mavch 22-24; and Experi- mental Atomic Spectroscopy, a day-release course to be held during the Summer Term. Further information can be obtained from L h . E. B. M. Steers, Physics Department, The Polytechnic of Korth London, Holloway, London, 1‘7 8DB.1st Workshop for Applications of Fluori- metric Enzyme Assays Apvil 14, 1976, Londolz This Workshop Meeting is to take place in the Meeting Rooms of the Zoological Society of London, Regent’s Park, and is being organised by l h . L). H. Leaback in association with Koch- Light Laboratories Ltd. of Colnbrook, Bucks. Subjects will include existing and potential applications as they affect the study of enzyme kinetics, genetics, forensic science and enzymes in single cells.There will bc a small display of apparatus, instruments and materials. Further details can be obtained from Dr. D. H. Leaback, Biochemistry Department, Institute of Orthopaedics, Stanmore, Middlesex, HA7 4LP, and workers with novel or interesting applications of the techniques are invited to suggest topics for discussion.EUCHEM Conference on Electroanalytical Chemistry: Developments in Voltammetry and Coulometry A p d 26-29, 1976, Skoklostev, Sweden This Conference is sponsored by the Swedish National Committee for Chemistry of the Royal Academy of Sciences, and by the Committee for EUCHEM Conferences. The following subjects will be covered : voltammetry at solid electrodes with special reference to methodology and instrumentation ;Fe hrua yy , 19 76 PUBLICATIONS RECEIVED 53 AC polarography-technique, instrumentation and novel applications ; and coulometric current efficiency and coulometry as an absolute analytical technique.Special emphasis will be laid upon : applications for determining trace elements; reactions of organic compounds a t electrodes ; and new principles in voltammetry and coulometry. Approximately ten main lectures will be given by guest speakers.Brief abstracts of discussion contributions will be required by April 2 , 1976. Participation will be limited to approximately 100 persons and i t may be necessary to decline late applica- tions. Correspondence should be addressed to Dr. (Mrs.) G.Aulin-Erdtman, The Swedish National Committee for Chemistry, Upplands- galan 6 -4, 1 tr. S-111 23 Stockholm, Sweden. Meeting on Scanning Transmission Elec- tron Microscopy May 5, 1976, London This one-day Meeting is being arranged by The Electron Microscopy and Analysis Group of The Institute of Physics and is to be held a t Imperial College, 1,ondon. For the majority of the meeting lectures will be given by invited speakers but there will be a small amount of time for contributions (closing date, April 5, 1976). Further details from : the Meeting Secretary, Mr. I(. Anderson, AEI Scientific Apparatus Division, Barton Dock Road, TJrmston, Man- Chester. The European Symposium of the Inter- national Association of Forensic Toxico - logists August 27-29, 1976, Ghent This Symposium will be held at the State University of Ghent, Belgium, in thc Dcpart- ment of Toxicology uf the Faculty of Pharma- ceutical Sciences. Further information can be obtained from Professor A. Heyndrickx, Department of Toxicology, State TJniversity of Ghent, Hospitaalstraat 13, 9000 Ghent, Belgium.

ISSN:0306-1396    

DOI:10.1039/AD9761300051

出版商:RSC    

年代:1976

数据来源: RSC

摘要:

Febyztary, 1976 PUBLICATIONS RECEIVED 53 Publications Received Reports on the Progress of Applied Chemistry during 1974. Volume 59. f’p. viii -1 612. Oxford, London, Edinburgh and Melbourne : Blackw-ell Scientific Publica- tions, for the Society of Chemical Industry. 1975. Price L20. Water Pollution Assessment : Automatic Sampling and Measurement. A Symposium presented a t the Seventy- seventh Annual Meeting of thc hiiierican Society for Testing and Materials, Washington, D.C., 23-28 June 1974.ASTM Special Technical Publication 582. Pp. vi + 218. Philadelphia : American Society for Testing and Materials. 1975. Price L6.50. Flame Emission and Atomic Absorption Spectrometry. Volume 3. Elements and Matrices. Edited by John A. Dean and Theodore C. Kains. Pp. xiv + 674.Kew York: Marcel Dekker, Inc. 1976. Price $49.50. Food Analysis : Analytical and Quality Control Methods for the Food Manu- facturer and Buyer, being the 3rd Edition of Laboratory Handbook of Methods of Food Analysis. R. Lees. Pp. x + 245. London: Leonard Hill Books. 1976. Price kS.50. Analytical Atomic Spectroscopy. William G. Schrenk. M o d e m A nal-ytical Chewistry. Py. xviii + 375. New Yvrk arid London : Plenum Press. 1975. f’ricc $39. Food Additives and Contaminants Com- mittee Review of the Lead in Food Regula- tions 1961. Ministry of Agriculture, Fisheries and Food. Pp. 49. London: HM Stationery Office. 1975. l’rice 65p. Survey of Lead in Food: First Supple- mentary Report. Working Party on the Monitoring of Foodstuffs for Heavy Metals Fifth Report. Ministry of Agriculture, Fisheries and Food. Pp. 34. London: HA1 Stationery Office. 1975. Price 50p.

ISSN:0306-1396    

DOI:10.1039/AD9761300053

出版商:RSC    

年代:1976

数据来源: RSC