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ANPRDI 18 (1-12) 1-552 (1981) ISSN 0144-557X - --- Proceedinas m - Proceedings of the Analytical Division of The Royal Society of Chemistry Volume 18 1981 Published by THE ROYAL SOCIETY OF CHEMISTRY BURLINGTON HOUSE, LONDON, W1V OBN Analvtical Proceedinas Proceedings of the Analytical Division of The Royal Society of Chemistry Officers of the Analytical Division of The Royal Society of Chemistry President L. S. Bark Hon. Treasurer D. C. M. Squirrel1 Hon. Secretary R. Sawyer Hon. Assistant Secretary D. I. Coomber Secretary Miss P. E. Hutchinson ANALYTICAL EDITORIAL BOARD Chairman J. M. Ottaway Hon. Publicity Secretary A. Townshend G. J. Dickes "G. W. Kirby J. M. Skinner J. D. R. Thomas A. M. Ure "P. C. Weston J.Whitehead J. N. Miller G. E. Penketh T. B. Pierce "Ex Officio members Editor, Analytical Proceedings P. C. Weston Assistant Editors Mrs. J. Brew, Mrs. P. A. Fellows, R. A. Young 0 The Royal Society of Chemistry, 1981 Printed by Heffers Printers Limited Cambridge England A B Baker, G. B. See Martin, I. L. ~ evolved gas analysis, 538. Bartle, K. D. See Jones, D. W. ~ Bezur, L. See Marshall, J. Service Award conferred on, 42. Burdisso, M. See Gallorini, M. C NAME INDEX Abraham, R. J. Conformational and structural studies by lanthanide-induced shifts, 364. Adams, F. See Chakraborti, D. Allan, J. G. See Fell, A. F. Ashworth, C. M., Castleden, S. L., and Kirkbright, G. F. Some novel applications of optoacoustic spectroscopy to real samples, 14.Bacon, J. R., and Ure, A. M. Spark source mass spectrometry for the analysis of non-conducting materials, 356. Bailey, F. The 1980 RSC Award for Chromato- graphy and Separation Chemistry to, 233. Bailey, F. J. See Crimes, A. A. Baker, A. A., and Headridge, J. B. Studies on the determination of low concentrations of nitrogen in gas streams, 16. Baker, P. G. Determination of polychlorodibenzo- p-dioxins, 478. Bark, L. S., and Kershaw, L. Rapid determination of isoniazid in simple dosage forms, 307. See Southway, C. Barnes, P. A., and Stephenson, G. Advances in Barton, J. M. Thermomechanical analysis and its applications, 42 1. Beckett, A. H. Doping in sport and some methods for its control, 114.Belcher, R. Awards in analytical chemistry, 182. Introductory lecture in trace and ultratrace analysis, 336. Berndt, H. Comparison of micro-techniques of flame atomic-absorption spectrometry (injection method, boat and cup system and platinum loop method), 353. Betteridge, D., Dagless, E. L.,.Fields, B:, Sweet, P., and Deans, D. R. Analytical chemistry a t the interface, 26. Bishop, ,E. The 1980 RSC award for Analytical Reactions and Analytical Reagents to, 233. Bracewell, J. M., and Robertson, G. W. Analytical potential of pyrolysis products derived from soil organic matter, 532. Braithwaite, A., and Henthorn, K. An introduction to microprocessors and their application to analytical chemistry, 60. Brown, R. H., and Walkin, K.T. Performance of a tube-type diffusive sampler for organic vapours in air, 205. Bryant, F. J. Analytical Division Distinguished Buckle, E. R., and Tsakiropoulos, P. The particles of heavy metal smokes : bismuth, lead, cadmium and zinc, 73. Burnill, P. J. Obituary, 41. Butt, W. R. Techniques of radioiodination, 100. Calam, D. H. See Pask-Hughes, R. A. Campbell, A. K. See Woodhead, J. S. ... Campbell, W. A. Edward Turner (1796-18371 and the atomic weight controversy, 381. Castleden, S. L. See Ashworth, C. M. Cave, M. R., Kaminaris, D. M., Ebdon, L., and ~ Mowthorpe, D. J. Fundamental studies of the application of an inductively coupled plasma to metallurgical analysis, 12. Winner of 1980 Rank Hilger Spectroscopy Prize, 87.Chakraborti, D., Jiang, S. G., Surkijn, P., de Jonghe, W., and Adams, F. Determination of tetra- alkyllead compounds in environmental samples by gas chromatography - graphite furnace atomic- absorption spectrometry, 347. Cook, J. D. Disposal of small amounts of toxic substances from the laboratory, 468. Cooke, M. Carbon skeleton capillary gas chromato- graphy, 158. Corfield, G. C., Ebdon, L., and Ellis, A. T. Some aspects of ion-selective electrodes with co- valently bound calcium sensors, 11 2. Corran, P. H. See Pask-Hughes, R. A. Coutts, R. T. See Martin, I. L. Coverly, S. C. Automated sample preparation for high-performance liquid chromatography : tech- niques, applications and some possibilities in food analysis, 491.Crimes, A. A., Bailey, F. J., and Hitchcock, C. H. S. Determination of foreign proteins in meat products, 164. Dagless, E. L. See Betteridge, D. Daniels, T. Introduction to thermomechanical methods, 412. Davies, D. C. See Gibbons, S. L. Davies, D. I. Biography of Charles Loudon Bloxam, 327. Dawkins, J. V. Chromatography of plastics, 395. Dawson, J. B. See Kersey, A. D. Deans, D. R. See Betteridge, D. De Antonio, S. M., Kate, S.. A., Scheiner, D. M., and Wood, J. D. Anatomical variations of trace metal levels in hair, 162. Deavin, J. C. See Williams, S. E. De Jonghe, W. See Chakraborti, D. Delfanti, R. See Orvini, E. Deron, S., and NavratiI, J. D. Chemical and isotopic reference materials in the nuclear fuel cycle, 331. Deverill, I.Immunoprecipitation and the centri- fugal fast analyser, 108. Dybowski, R. Examination of amygdalin prepara- tions, 316. Dyer, A. New member of Council, 231. - Thermomechanical analysis of zeolites, 447. - See Molokhia, A. Ebdon, L. See Cave, M. R., Corfield, G. C. Egan, H. Obituary of J. K. Foreman, 53. Elejalde, C., Gracia, I., and Gurtubay, L. Deter- mination of Biscay atmospheric pollution by rainwater analysis, 192. Elliott, G. E. P., Marshall, B. W., 8nd Smith, A. C. Aspects of the analysis of selenium in water treatment wastes, 64. Ellis, A. T. See Corfield, G. C. Elyas, A. See Goldberg, V. 111 D E ANALYTICAL PROCEEDINGS iv Emslie, J. J., Kaseke, C. T., and Tyson, J. F. Deter- mination of mercury vapour in laboratory atmospheres, 67.England, J. C., Long, R. F., and Townend, D: J. Hassan, S. K. A. G., Jones, C. G. D., Jones, D. L., Moody, G. J., and Thomas, J. D. R. Develop- Research application of dynamic mechanical analysis to polymeric systems, 430. Evans, N. Application of direct pyrolysis - mass spectrometry to the analysis of polyurethane and epoxy resins, 535. F foods, 396. Hitchcock, C. H. S. See Crimes, A. A. Fairweather-Tait, S. J. The availability of iron in Hoang, H. See Sherman, L. R. Howe, A. M. See Jackson, C. J. Huddleston, J., Hutchinson, I. G., and Pierce, T. B. Fakhrul-Aldeen, R. See Marshall, J. Farmer, J. G. The analytical chemist in studies of metal pollution in sediment cores, 249. Fayad, N. M. See Fogg, A.G. Fell, A. F., and Allan, J. G. Analysis of colouring agents in pharmaceuticals by derivative ultra- violet - visible spectroscopy, 291. Fields, B. See Betteridge, D. Fogg, A. G., Fayad, N. M., and Martin, M. J. Degradation studies of penicillins and cephalo- sporins using polarography, 2 11. - Voltammetry: is it worth considering? 387. Forbes, S. Some recent developments in thin-layer chromatography, 19. Foreman, J. K. Obituary, 53. Frischkorn, C. G. B. See Smyth, M. R. G Gallorini, M., Orvini, E., Rolla, A., and Burdisso, M. Radiochemical neutron-activation analysis of trace elements in suspended materials released from refuse incinerators, 199. ___ See Orvini, E. Gijbels, R. See Tavernier, S. M. F. Gillham, J. K. Application of torsional braid analysis to the cure and properties of thermo- setting systems, 424.Goldberg, V., Ratnaraj, N., Elyas, A., and Lascelles, P. T. New methods for the determination of anticonvulsant drugs, 3 13. Gracia, I. See Elejalde, C. centrifugal analyser, 71. Gurtubay, L. See Elejalde, C. H stains, 299. Hansen, E. H. Flow injection analysis: new analytical methods based on the use of potentio- metric and spectrophotometric flow-through detectors, 261. Harris, J. R. Medicinal additives in animal feeding stuffs, 485. fuel extracts by NMR spectroscopy, 362. Gibbons, S. L., and Davies, D. C. Design of labora- Jordan, C., and Svehla, G. A voltammetric study tories for handling toxic substances, 467. Griffiths, D.F. Analytical chemistry-catch them Kersey, A. D., and Dawson, J. B. Comparison of youig. (Editorial), 97. - 1 he 1980 RSC Award for Inorganic Industrial Analysis to, 233. Griffiths, P. D. Immunoglobulin assay using a Halls, D. J. Applications of graphite furnace atomic-absorption spectrometry in clinical analysis, 344. Ham, G. Refractive index effect in flow injection analysis, 69. Hammond, M. D. Detection of drugs in blood Lewis, C. J., and Vose, C. W. Gas chromatographic Jones, D. L. See Hassan, S. K. A. G. of the osazone of dihydroxytartaric acid, 243. K Kakabadse, G. J. Ion-selective electrodes in organic solvents, 255. Kaminaris, D. M. See Cave, M. R. Kaseke, C. T. See Emslie, J. J. Kstz, S. A. See De Antonio, S. M. detection limits in magnetically induced optical rotation and atomic-absorption spectroscopy, 187.Kershaw, J. R. Luminescence spectroscopic analysis of coal hydrogenation liquids, 155. Kershaw, L. See Bark, L. S. Kirkbright, G. F. The 1980 RSC award for Analytical Spectroscopy to, 233. - See Ashworth, C. M. Kcicka, L. J. Ninth Society for Analytical Chemis- try Silver Medal awarded to, 500. L Lascelles, P. T. See Goldberg, V. profiling of urinary metabolites of ethynodiol diacetate, 253. Lines, R. W. Particle counting by Coulter Counter, 514. Long, R. F. See England, J. C. Lyle, S. J., and Saleh, M. I. Some observations on the application of electrochemical detectors in high-performance liquid chromatography, 24. Hart, R. See Woodhead, J.S. Hasbm, J. Obituary of, 500. Haslop, D. Air-borne and liquid-borne particle counters, 519. ment of ion-selective electrodes based on polymer matrix membranes, 241. Headridge, J. B. See Baker, A. A. Henthorn, K. See Braithwaite, A. Hill, W. H. Safety in analytical laboratories. (Correspondence), 40. Microcomputer-based data-processing system for carbon profiling with the nuclear microprobe, 208. Hunt, D. C. Methods for the determination of mycotoxins, 471. Hutchinson, I. G. See Huddleston, J. J Jackson, C.. J., Neuberger, C., and Taylor, M. Applicability and cost effectiveness of ion chro- matographic and ion-selective electrode tech- niques as applied to environmental monitoring by the Health and Safety Executive, 201.---, Howe, A. M., and Neuberger, C. Sampling and analysis of galvanising fume, 234. Jennings, V. J. Determination of trace amounts of organic substances by polarography, 339. Jiang, S. G. See Chakraborti, D. Johnson, W. C., MBE. Obituary, 54. Jones, C. G. D. See Hassan, S. K. A. G. Jones, D. W., and Bartle, K. D. Analysis of fossil- INDEX TO VOLUME 18 M Mackenzie, R. New member of Council, 231. Mapperley, B. W. See Sewell, P. R. Marks, V. Measurement of drugs in biological fluids by immunoassay, 389. Marshall, B. W. See Elliott, G. E. P. Marshall, J., Bezur, L., Fakhrul-Aldeen, R., and Ottaway, J. M. Carbon furnace atomic emission using platform atomisation, 10. Martin, I. L., Baker, G. B., and Coutts, R. T. Analysis of brain amines using gas chromato- graphy with electron-capture detection, 297.Martin, M. J. See Fogg, A. G. Mason, B., and Tranter, J. Use of high-performance liquid chromatography for the determination of cephalexin, 310. Matthews, B. R. The pharmacopoeia1 attitude on particle counting in large-volume injectable solutions, 525. McCapra, F. See Woodhead, J. S. McNeill, I. C. Applications of thermal volatilisation analysis, 540. McNulty, D. W. See Williams, S. E. Melius, P. See Tan, B. Mesley, .R. J. Harmonisation of collaborative analytical studies, 461. Miller, J. N. Continuing education in analytical chemistry. (Editorial), 227. - Luminescence detection in flow injection analysis, 264. - SEKC backs analytical science. (Editorial), 507.Mitchell, F. L. Discrete analysis with continuous optical scanning, 257. Moffat, A. C. Award of 8th Society for Analytical Chemistry Silver Medal to, 229. __ Combined high-performance liquid chromato- graphy - immunoassays for drugs and metab- olites in biological fluids, 115. Molokhia, A., Portnoy, B., and Dyer, A. Multi- element instrumental neutron activation analysis of human skin, 160. Moody, G. J. See Hassan, S. .K. A. G. Moody, J. R. Sample handling for trace element analysis, 337. Morrell, R. Applications of thermodilatometry to ceramic science, 443. MOSS, M. S. Horse doping: history, control and trends, 114. Mowthorpe, D. J. See Cave, M. R. 426. N Navratil, J. D. See Deron, S. Neuberger, C. See Jackson, C.J. Newall, R. H. AppIications of therniodilatometry in metallurgy, 440. Nies, E. See Tavernier, S. M. F. Niirnberg, H. W. See Smyth, M. R. 0 Ogilvie, G. D. Laser microprobes and the analysis of textile defects, 117. - Thermal stress properties of synthetic fibres, Orvini, E., Delfanti, R., Gallorini, M., and Speziali, Snowsill, W. L. On-line dust monitoring in the M. Determination of trace amounts of arsenic(\') and arsenic(II1) in natural waters by neutron- activation analysis, 237. - See Gallorini, M. V Osborne, B. G. Application of near infrared reflec- tance spectroscopy to the analysis of food, 488. Osibanjo, 0. Biography, 55. O'Sullivan, M. J. Enzyme immunoassay, 104. Ottaway, J. M. See Marshall, J. analysis, 267.-, Raine, D. N. Obituary, 41, 183. Ratnaraj, N. See Goldberg, V. See Bracewell, J. M. Robertson, G. W. RoUa, A. See Gallorini, M. Rubinstein, M. H. Particle size analysis as a predictor of dissolution rate/bioavailability, 5 12. RfiiiEka, J. Theory and principles of flow injection Ryall, M. E. T. See Woodhead, J. S. P Pask-Hughes, R. A., Corran, .P. H., and Calam, D. H. The assay of combined pharmaceutical products by high-performance liquid chromato- graphy, 247. Paterson, E. First TMG award to, 230. Peake, D. M. Obituary of D. N. Raine, 183. Pierce, T. B. See Huddleston, J. Pitt, 1. J. Training of analytical chemists. (Correspondence), 87. Portnoy, B. See Molokhia, A. Price, C. P. Centrifugal analysers in clinical chemistry, 259.Price, W. J. Safety in analytical laboratories. (Correspondence), 41. Purnell, C. J., and Warwick, C. J. Application of electrochemical detection in high-performance liquid chromatography to the measurement of toxic substances in air, 151. and Walker, R. F. Methods for the deter- mination of atmospheric isocyanates, 472. R S Saleh, M. I. See Lyle, S. J. Sansom, P. C. Applications of chromatography to the analysis of paints, 393. Scheiner, D. M. See De Antonio, S. M. Scott, M. G. Applications of TMA in the study of metallic glasses, 437. Sewell, P. R., and Mapperley, B. W. Application of chromatographic methods in the rubber industry, 395. Sherman, L. R., and Eoang, H. The bioassay and analysis of tributyltin fluoride, 196.Sherrard, T. J., and Speakman, P. T. Electro- phoretic techniques used to study the hetero- geneity of wool high-sulphur proteins, 1 16. Simpson, J. S. A. See Woodhead, J. S. Smith, A. C. See Elliott, G. E. P. Smith, R. 1. Use of the microcomputer in the teaching of chromatography, 158. Smyth, M. R., Frischkorn, C. G. B., and Niirnberg, H. W. A critical appraisal of the application of chromatovoltammetry in biological and environ- mental chemistry, 215. Snook, R. D. A critical appraisal of the hydride generation method, 342. Central Electricity Generating Board, 528. Southway, C., and Bark, L. S. A systematic investi- gation of the COD test for estuarine waters, 7. Speakman, P. T. See Sherrard, T. J. ANALYTICAL PROCEEDINGS vi Spence, J.Implications of particle contamination standards for small-volume injections for the pharmaceutical industry, 522. - Relevance and advantages of the Coulter Counter for standardisation and quality control of pharmaceuticals, 509. Spedali, M. See Orvini, E. Steele, D. J. Process instrumentation in the food factory, 489. Stephenson, G. See Barnes, P. A. Stewart, G. D. See Tyson, J. F. Surkijn, P. See Chakraborti, D. Svehla, G. See Jordan, C. Sweet, P. See Betteridge, D. T assay of epoxide hydrolase activity and deter- mination of 1,2-diols via digested lead periodate, 384. Tavernier, S. M. F., Nies, E., and Gijbels, R. Hard- sphere model for hydrodynamic chromatography systems, 31. Taylor, M.See Jackson, C. J. Thomas, J. D. R. Academic research in analytical chemistry. (Correspondence), 84. - Direct potentiometry for trace and ultra-trace analysis, 350. - See Hassan, S. K. A. G. Thomas, W. A. Small-sample NMR spectroscopy : - On meetings. (Editorial), 51. scope and limitations, 366. Thorburn Burns, D. Aspects of the chemical, medical and social history of mineral waters and baths, 463. - A touch-stone for gold and silver wares, 146. - Supply of and demand for analytical chemists, Thomas Guidott (1638-1705) : physician and chymist, contributor to the analysis of mineral waters. Biography, 2. Tan, B., and Melius, P. Indirect atomic-absorption Warwick, C. J. See Purnell, C. J. v Vose, C. W. See Lewis, C. J. W Walker, R.F. See Purnell, C. J. Walkin, K. T. See Brown, R. H. Watson, C. A. Development and testing of hydride generation methods for antimony and selenium in organic matter-the work of the Metallic Impurities in Organic Matter Sub-committee of the Analytical Methods Committee, 482. - New member of Council, 232. Weston, P. C. Times to publication of research papers. (Editorial), 1. __What’s the hold-up? (Editorial), 181. Wetton, R. E. Dynamic mechanical measurements and their application to polymer systems, 416. Whitehead, J. New member of Council, 233. Whiteoak, R. J. New member of Council, 281. Whitley, J. E. New member of Council, 233. Williams, D. R. Development and evaluation of work of the new analytical methods-the Analytical Methods Committee, 480.Williams, S. E., McNulty, D. W., and Deavin, J. C. Comparison of allergenic extracts using micro- isoelectric focusing, 303. Winefordner, J. D. Lasers in analytical spectro- metry (Tenth Theophilus Redwood lecture), 284. Wood, J. D. See De Antonio, S. M. Woodhead, J. S., Simpson, J. S. A., Campbell, A. K., Ryall, M. E. T., Hart, R., and McCapra, F. Chemiluminescence immunoassay, 102. Y Yardley, J. T. Obituary of W. C. Johnson, MRE, 54. Young, R. A. Splitting the package. (Editorial), - 56. Toseland, P. A. Measurement of therapeutic drugs Wiseman, A. New analytical uses for enzymes, 359. in a busy clinical laboratory, 391. Townend, D. J. See England, J. C. Tranter, J. See Mason, B. Tsakiropoulos, P.See Buckle, E. R. Tyson, J. F. Analytical aspects of gas-phase Auger electron spectrometry, 120. - Flow-inj ection techniques in atomic-absorption spectrometry, 542. - New member of Council, 231. -, and Stewart, G. D. Indirect atomic-absorption methods based on molybdenum heteropoly acids using carbon rod electrothermal atomisation, 184. - See Emslie, J. J. U Uden, P. C. Specific element detection in high- resolution gas chromatography by plasma emission spectroscopy, 189. Ure, A. M. See Bacon, J. R. 411. INDEX TO VOLUME 18 A Academic research in analytical chemistry. Thomas. (Correspondence), 84. Air : Application of electrochemical detection in high-performance liquid chromatography to the measurement of toxic substances in -.Purnell and Warwick, 151. Performance of a tube-type diffusive sampler for organic vapours in -. 205. Air-borne particles: A4ir-borne and liquid-borne particle counters. Haslop, 519. Allergenic extracts: Comparison of - using micro- isoelectric focusing. Williams, McNulty and Deavin, 303. Dybowskl, 3 16. Analytical chemist: The ~ Amygdalin preparations : Examination of --. in studies of metal pollution in sediment cores. Farmer, 249. Analytical Chemistry-Catch them young. Griffiths. Thomas. (Corre- Braithwaite and Hen- (Editorial), 97. -Trust Fund, 508. Academic research in -. spondence), 84. An introduction to microprocessors and their application to -. Miller. (Edi- thorn, 60. Awards in -. Belcher, 182.Continuing education in -. torial), 227. Analytical chemists: Supply of and demand for -. Thorburn Burns, 56. Pitt. (Correspondence), 87. Training of -. Analytical journals package: Splitting the package. SUBJECT INDEX Brown and Walkin, Analytical Methods Committee : . Development and evaluation of new analytlcal methods-the work of the -. Williams, 480. Development and testing of hydride generation methods for antimony and selenium in organic matter-the work of the Metallic Impurities in Organic Matter Sub-committee of the -. Watson, 482. Medicinal additives in animal feeding stuffs. Harris, 485. Analytical Proceedings : What’s the hold-up ? Weston. (Editorial), 181. Miller. Analytical science: SERC backs -. (Editorial), 507.Anatomical variations of trace metal levels in hair. De Antonio, Katz, Scheiner and Wood, 162. Animal feeding stuffs: Medicinal additives in -. Goldberg, Ratnaraj, Elyas Harris, 485. Anticonvulsant drugs: New methods for the deter- mination of -. and Lascelles, 313. Antimony determination: Development and testing of hydride generation methods for antimony and selenium in organic matter-the work of the Metallic Impurities in Organic Matter Sub-committee of the Analytical Methods Committee. Watson, 482. Arsenic(V) and -(In) determination: Determination of trace amounts of arsenic(V) and arsenic(II1) in natural waters by neutron-activation analysis. Orvini, Delfanti, Gallorini and Speziali, 237. 318. Atmospheric pollution: Determination of Biscay - by rainwater analysis.Elejalde, Gracia Association of Public Analysts: The -, and Gurtubay, 192. Atomic-absorption spectrometry or spectroscopy : See Spectrometry, atomic-absorption. Atomic emission spectrometry : See Spectrometry, atomic emission. Auger electron spectrometry: See Spectrometry, Auger electron. Automated sample preparation for high-performance liquid chromatography : techniques, applica- tions and some possibilities in food analysis. Coverly, 491. Awards in analytical chemistry. Belcher, 182. Marks, 389. Analytical Division: 9th A.G.M., 143. Atomic Spectroscopy Group. 16th A.G.M., 98. Automatic Methods Group. 15th A.G.M., 145. Biological Methods Group. 36th A.G.M., 98.Chromatography and Electrophoresis Group. 16th -4.G.M., 145. Distinguished Service Award conferred on F. J. Bryant, 42. East Anglia Region. 13th A.G.M., 52. Education and Training Group. 10th A.G.M., 98. Electroanalytical Group. 11th A.G.M., 145. Joint Pharmaceutical Analysis Group. 1 l t h A.G.M., 145. Microchemical Methods Group. 37th A.G.M., 145. Midlands Region. 26th A.G.M., 144. New members of Council, 231, 281. North East Region. 15th A.G.M., 144. North West Region. 56th A.G.M., 144. North West Region. Combined liquid chromato- graphy - mass spectrometry, 98. Particle Size Analysis Group. 15th A.G.M., 52. Radiochemical Methods Group. 14th A.G.M., 52. Scottish Region. 46th A.G.M., 52. South East Region. 6th A.G.M., 182.Special Techniques Group. 36th A.G.M., 229. 10th Theophilus Redwood Lecture by J. D. Winefordner, 284. Thermal Methods Group. First TMG award to E. Paterson, 230. Thermal Methods Group. 16th A.G.M., 52. Western Region. 26th A.G.M., 229. Young. (Editorial), 411. vii B Baths: Aspects of the chemical, medical and social history of mineral waters and ---. Thorburn Burns, 463. Bioassay: The - and analysis of tributyltin fluoride. Sherman and Hoang, 196. Bioavailability : Particle size analysis as a predictor of dissolution rate/----. Rubinstein, 512. Biological chemistry : A critical appraisal of the application of chromatovoltammetry in bio- logical and environmental chemistry. Smyth, Frischkorn and Niirnberg, 215. Biological fluids : Combined high-performance liquid chromatography - immunoassays for drugs and metabolites in -.Moffat, 115. Measurement of drugs in - by immunoassay. ANALYTICAL PROCEEDINGS viii -, Hammond, Bismuth: The particles of heavy metal smokes : lead, cadmium and zinc. Buckle and Tsakiropoulos, 73. Blood stains: Detection of drugs in -. 299. Bloxam, Charles Loudon: Biography. Davies, 327. Boat and. cup flame atomic-absorption : Comparison of micro-techniques of flame atomic-absorption spectrometry (injection method, boat and cup system and platinum loop method). Berndt, 353. Brain amines: Analysis of - using gas chromato- graphy with electron-capture detection. Martin, Baker and Coutts, 297. British Standards: 43, 233.C Cadmium: The particles of heavy metal smokes : bismuth, lead, - and zinc. Buckle and Tsakiropoulos, 73. Calcium sensors: Some aspects of ion-selective Cor- electrodes with covalently bound -. field, Ebdon and Ellis, 112. Capillary gas chromatography. See Chrompto- graphy, capillary gas. Carbon furnace atomic emission using platform atomisation. Marshall, Bezur, Fakhrul-Aldeen and Ottaway, 10. Carbon proWng: Microcomputer-based data-pro- cessing system for - with the nuclear microprobe. Huddleston, Hutchinson and Pierce, 208. Carbon rod: Indirect atomic-absorption methods based on molybdenum heteropoly acids using - electrothermal atomisation. Tyson and Stewart, 184. Carbon skeleton capillary gas chromatography. Cooke, 158.Centrifugal analysers in clinical chemistry. Price, Discrete analysis with continuous optical scan- Immunoglobin assay using a centrifugal analyser. Centrifugal fast analyser : Immunoprecipitation and 259. ning. Mitchell, 257. Griffiths, 71. the -. Deverill, 108. liquid chromatography for the determination Cephalexin determination: Use of high-performance of cephalexin, 310. Cephalosporins: Degradation studies of penicillins and - using polarography. Fogg, Fayad and Martin, 211. Ceramic science: Applications of thermodilatometry to -. Morrell, 443. tion of the COD test for estuarine waters. Chemical oxygen demand: A systematic investiga- Southway and Bark, 7. Woodhead, Simpson, Campbell, Ryall, Hart and McCapra, -, Chromatography, capillary gas : Carbon skeleton Chemiluminescence immunoassay.102. Chromatography of plastics. Dawkins, 395. Application of chromatographic methods in the rubber industry. Sewell and Mapperley, 395. Applications of - to the analysis of paints. Sansom, 393. Methods for the determination of mycotoxins. Hunt, 471. Use of the microcomputer in the teaching of Smith, 158. capillary gas chromatography. Cooke, 158. Chromatography, gas : Analysis of brain amines using gas chromatography with electron- capture detection. Martin, Baker and Coutts, Determination of polychlorodibenzo-pdioxins. Chromatography, gel-permeation: Chromatography 297. Baker, 478. Determination of tetraalkyllead compounds in environmental samples by gas chromato- graphy - graphite furnace atomic-absorption spectrometry. Chakraborti, Jiang, Surkijn, De Jonghe and Adams, 347.Gas chromatographic profiling of urinary metab- olites of ethynodiol diacetate. Lewis and Vose, 253. of plastics. Dawkins, 395. Chromatography, high-perf ormance lipuid ; Appli- cation of electrochemical detection in high- performance liquid chromatography to the measurement of toxic substances in air. Purnell and Warwick, 151. Automated sample preparation for high-perform- ance liquid chromatography : techniques, appli- cations and some possibilities in food analysis. Coverly, 49 1. Combined high-performance liquid chromato- graphy - immunoassays for drugs and metab- olites in biological fluids. Moffat, 115.Examination of amygdalin preparations. Dybow- ski, 316. Some observations on the application of electro- chemical detectors in high-performance liquid chromatography. Lyle and Saleh, 24. The assay of combined pharmaceutical products by high-performance liquid chromatography. Pask-Hughes, Corran and Calam, 247. Use of high-performance liquid chromatography for the determination of cephalexin. Mason and Tranter, 310. Chromatography, high-resolution gas : Specific ele- ment detection in high-resolution gas chromato- graphy by plasma emission spectroscopy. Uden, 189. Chromatography, hydrodynamic : Hard-sphere model for hydrodynamic chromatography systems. Tavernier, Nies and Gijbels, 31. Chromatography, ion : Applicability and cost effectiveness of ion chromatographic and ion- selective electrode techniques as applied to environmental monitoring by the Health and Safety Executive.Jackson, Neuberger and Taylor, 201. ments in thin-layer chromatography. Forbes, Chromatography, thin-layer : Some recent develop- 19. Chromatovoltammetry: A critical appraisal of the application of - in biological and environ- mental chemistry. Smyth, Frischkorn and Nurnberg, 215. Clinical analysis : Applications of graphite furnace Halls, atomic-absorption spectrometry in ---. Clinical chemistry: Centrifugal analysers in -. Price, 259. Kershaw, 155. 344. scopic analysis of -. Coal hydrogenation liquids : Luminescence spectro- Collaborative analytical studies : Harmonisation of - .Mesley, 461. Colouring agents: Analysis of - in pharmaceuti- cals bv derivative ultraviolet - visible sDectro- scopy. Fell and Allan, 291. INDEX TO VOLUME 18 Combined pharmaceutical products: The assay of - by high-performance liquid chromato- graphy. Pask-Hughes, Corran and Calam, 247. Lines, Computers : See Microprocessors. Conformational studies : Conformational and struc- tural studies by lanthanide-induced shifts. Abraham, 364. Mitchell, 257. -. Correspondence : 84, 8 7. Continuous optical scanning : Discrete analysis with Coulter Counter : Particle counting by -. 514. Relevance and advantages of the -- for standardisation and quality control of pharma- ceuticals. Spence, 509. D Data processing : Microcomputer-based - system for carbon profiling with the nuclear micro- probe.Huddleston, Hutchinson and Pierce, 208. Degradation studies of penicillins and cephalo- sporins using polarography. Fogg, Fayad and Martin, 21 1 . Derivative spectroscopy: Analysis of colouring agents in pharmaceuticals by derivative ultra- violet - visible spectroscopy. Fell and Allan, 291. Detection limits : Comparison of __ in magnetically induced optical rotation and atomic-absorption spectroscopy. Kersey and Dawson, 187. Dihydroxytartaric acid: A voltammetric study of the osazone of -. Jordan and Svehla, 243. 1,2-Diol determination: Indirect atomic-absorption assay of epoxide hydrolase activity and deter- mination of 1,2-diols via digested lead periodate.Tan and Melius, 384. Discrete analysis with continuous optical scanning. Mitchell, 257. Dissolution rate: Particle size analysis as a predictor Rubinstein, 512. of ----/bioavailability. Distinguished Service Award: Conferred on F. J . Enzyme multiplied immunoassay technique : New Bryant, 42. Doping in sport and some methods for its control. Beckett, 114. Horse -: history, control and trends. Moss, Drug detection: Detection of drugs in blood stains. Hammond, 299. Drug determination: Combined high-performance liquid chromatography - immunoassays for drugs aad metabolites in biological fluids. Moffat, 115. 114. Drug measurement: Measurement of drugs in biological fluids by immunoassay. Marks, 389. Measurement of therapeutic drugs in a busy clinical laboratory.Toseland, 39 1. Dust monitoring: On-line - in the Central Electricity Generating Board. Snowsill, 528. Wiseman, methods for the determination of anti- convulsant drugs. Goldberg, Ratnaraj , Elyas and Lascelles, 313. Enzymes: New analytical uses for -. 359. Epoxide hydrolase activity: Indirect atomic-absorp- tion assay of ~ and determination of 1,2- diols via digested lead periodate. Tan and Melius, 384. Epoxy resins: Applications of direct pyrolysis - mass spectrometry to the analysis of poly- urethane and -. Evans, 535. Equipment news: 34, 76, 121,167,218,269,319,369, 399, 450, 494, 546. Ergometrine assay: The assay of combined pharma- ceutical products by high-performance liquid chromatography.Pask-Hughes, Corran and Calam, 247. Estuarine waters : A systematic investigation of the COD test for estuarine waters. Southway and Bark, 7. Ethynodiol diacetate : Gas chromatographic profiling Lewis and of urinary metabolites of -. Vose, 253. Dynamic thermomechanometry: Introduction to Dynamic mechanical measurements and their application to polymer systems. Wetton, 416. Research applications of dynamic mechanical analysis to polymeric systems. England, Long and Townend, 430. thermomechanical methods. Daniels, 412. ix E Editorial: 1, 51, 97, 181, 227, 411, 507. Education: Continuing - in analytical chemistry. Miller. (Editorial), 227. Supply of and demand for analytical chemists. Thorburn Burns, 56.Electrochemical detection: Application of - in high-performance liquid chromatography to the measurement of toxic substances in air. Purnell and Warwick, 151. Some observations on the application of electro- chemical detectors in high-performance liquid chromatography, Lyle and Saleh, 24. Martin, using gas chromatography with -. Baker and Coutts, 297. Electrophoretic techniques used to study the Electron-capture detection: Analysis of brain amines heterogeneity of wool high-sulphur proteins. Sherrard and Speakman, 116. Electrothermal atomisation: Indirect atomic- absorption methods based on molybdenum heteropoly acids using carbon rod --. Tyson and Stewart, 184. Employment: Supply of and demand for analytical chemists.Thorburn Burns, 56. Enthalpimetry : Rapid determination of isoniazid in simple dosage forms. Bark and Kershaw, 307. Environmental chemistry: A critical appraisal of the application of chromatovoltammetry in bio- logical and --. Smyth, Frischkorn and Niirnberg, 215. Environmental monitoring : Applicability and cost effectiveness of ion chromatographic and ion- selective electrode techniques as applied to -- by the Health and Safety Executive. Jackson, Neuberger and Taylor, 201. Environmental samples: Determination of tetra- alkyllead compounds in __ by gas chroma- tography - graphite furnace atomic-absorption spectrometry. Chakraborti, Jiang, Surkijn, De Jong and Adams, 347. O’Sullivan, 104. -. Enzyme-linked immunosorbent assay : Determina- Enzyme immunoassay : See also Enzymes.tion of foreign proteins in meat products. Crimes, Bailey and Hitchcock, 164. X ANALYTICAL PROCEEDINGS European analysis : European Analytical Column 4. Hard-sphere theory: Hard-sphere model for hydro- Federation of European Chemical Societies Working Party on Analytical Chemistry, 282. Barnes Evolved gas analysis: Advances in -. and Stephenson, 538. F Flow injection analysis: new analytical methods based on the use of potentiometric and spectro- photometric flow-through detectors. Hansen, Miller, 264. Ham, 69. KGiiEka, 267. 261. Analytical chemistry a t the interface. Betteridge, Dagless, Fields, Sweet and Deans, 26. Flow-injection techniques in atomic-absorption spectrometry.Tyson, 542. Luminescence detection in -. Refractive index effect in -. spectroscopy to the analysis of -. Theory and principles of -. Food: Application of near infrared reflectance Osborne, 488. Automated sample preparation for high-perform- ance liquid chromatography : techniques, appli- cations and some possibilities in ___ analysis. Coverly, 491. factory. Process instrumentation in the ~ Steele, 489. The availability of iron in foods. Fairweather- Tait, 396. foreign proteins in meat products. Crimes, Bailey and Hitchcock, 164. Foreign protein determination: Determination of Foreman, J. K.: Obituary. Egan, 53. Fossil-fuel extracts: Analysis of __ by NMR spectroscopy. Jones and Bartle, 362. G Galvanising fume: Sampling and analysis of -.Jackson, Howe and Neuberger, 234. Gas Gas - chromatography liquid chromatography : See Chromatography, : See Chromatography, gas. gas. Gas-phase spectrometry: See Spectrometry, gas- Gas streams: Studies on the determination of low Baker and phase. concentrations of nitrogen in -. Headridge, 16. Gel-permeation chromatography : See Chromato- graphy, gel-permeation. atomic- absorption spectrometry in clinical analysis. Halls, 344. Graphite furnace: Applications of ~ Determination of tetraalkyllead compounds in environmental samples by gas chromato- graphy - - atomic-absorption spectrometry. Chakraborti, Jiang, Surkijn, De Jonghe and Adams, 347. Guidott, T. : Thomas Guidott (1638-1705) : physician and chymist, contributor to the analysis of mineral waters.Biography. Thorburn Burns, 2. H Hair : Anatomical variations of trace metal levels in-. De Antonio, Katz, Scheiner and Wood, 162. dynamic chromatography systems. Tavernier, Nies and Gijbels, 31. Hazardous substances: Measurement of --. Health and Safety Executive, 283. Heavy metal smokes: The particles of -: bismuth, lead, cadmium and zinc. Buckle and Tsakiropoulos, 73. High-performance liquid chromatography : See Chromatography, high-performance liquid. High-performance thin-layer chromatography : Some recent developments in thin-layer chro- matography. Forbes, 19. High-resolution gas chromatography: See Chroma- t ogr aph y, high-r esolu tion gas.History, chemical, medical and social: Aspects of the chemical, medical and social history of mineral waters and baths. Thorburn Burns, 463. Human skin: Multi-element instrumental neutron Molokhia, Portnoy activation analysis of -. and Dyer, 160. Hydride generation: A critical appraisal of the - method. Snook, 342. Development and testing of - methods for antimony and selenium in organic matter- the work of the Metallic Impurities in Organic Matter Sub-committee of the Analytical Methods Committee, Watson, 482. Hydrodynamic chromatography: See Chromato- graphy, hydrodynamic. I Immunoassay : Chemiluminescence -. Wood- head, Simpson, Campbell, Ryall, Hart and McCapra, 102. Combined high-performance liquid chromato- graphy - immunoassays for drugs and metab- olites in biological fluids.Moffat, 115. Eyzyme -. O’Sullivan, 104. Immunoprecipitation and the centrifugal fast analyser. Deverill, 108. Measurement of drugs in biological fluids by -. Marks, 389. Techniques of radioiodination. Butt, 100. Immunoglobulin assay using a centrifugal analyser. Griffiths, 71. Immunoprecipitation and the centrifugal fast analyser. Deverill, 108. Immunoturbidimetry: Immunoglobulin assay using a centrifugal analyser. Griffiths, 71. Inductively coupled plasma : Fundamental studies of the application of an - to metallurgical analysis. Cave, Kaminaris, Ebdon and Mow- thorpe, 12. Injection flame atomic-absorption : Comparison of micro-techniques of flame atomic-absorption spectrometry (injection method, boat and cup system and platinum loop method).Berndt, 353. Interface: Analytical chemistry at the -. Betteridge, Dagless, Fields, Sweet and Deans, 26. Ion chromatography: See Chromatography, ion. Ion-selective electrodes in organic solvents. Kaka- badse, 255. Applicability and cost effectiveness of ion chro- matographic and ion-selective electrode tech- niques as applied to environmental monitoring bv the Health and Safetv Executive. Tackson. Neuberger and Taylor, i O l . INDEX TO VOLUME 18 Ion-selective electrodes-continued Development of - based on polymer matrix membranes. Hassan, Jones, Jones, Moody and Thomas, 241. Direct potentiometry for trace and ultra-trace analysis.Thomas, 350. Some aspects of ___ with covalently bound calcium sensors. Corfield, Ebdon and Ellis, 112. Iron: The availability of - in foods. Fair- weather-Tait, 396. Isocyanates, atmospheric : Methods for the deter- mination of atmospheric isocyanates. Purnell and Walker, 472. Isoniazid determination : See Isonicotinic acid hydrazide determination. Isonicotinic acid hydrazide determination : Rapid determination of isoniazid in simple dosage forms. Bark and Kershaw, 307. the nuclear fuel cycle. Deron and Navratil, Isotopic reference materials: Chemical and - in 331. J L Laboratory atmospheres : Determination of mercury vapour in-. Emslie, Kaseke and Tyson, Johnson, W. C., MBE: Obituary. Yardley, 54. Abraham, 364. 67.Laboratory design : Design of laboratories for handling toxic substances. Gibbons and Davies, 467. structural studies by -. Loughborough University : New appointments at Lanthanide-induced shifts : Conformational and Large-volume injections : The pharmacopoeia1 atti- tude on particle counting in large-volume injectable solutions. Matthews, 525. Laser microprobes and the analysis of textile defects. Ogilvie, 117. Lasers in analytical spectrometry. Winefordner, Tan and 284. Lead: The particles of heavy metal smokes: cadmium and zinc. Buckle bismuth, -, and Tsakiropoulos, 73. Lead periodate : Indirect atomic-absorption assay of epoxide hydrolase activity and determina- tion of 1,2-diols via digested-. Liquid-borne particles : Air-borne and liquid-borne Melius, 384.particle counters. Haslop, 519. Loughborough, 322. Luminescence detection in flow injection analysis. Miller, 264. Luminescence spectroscopy : See Spectroscopy, lumi- nescence. M of detection limits in __ and atomic-absorp- Kersey and Dawson, 187. Magnetically induced optical rotation : Comparison tion spectroscopy. 485. Mass spectrometry: See Spectrometry, mass. Meat products: Determination of foreign proteins in -. Crimes, Bailey and Hitchcock, 164. Medicinal additives in animal feeding stuffs. Harris, Whitehead. (Editorial), 51. Meetings: On -. xi Mercury vapour : Determination of __ in labora- tory atmospheres. Emslie, Kaseke and Tyson, 67. Metabolite determination: Combined high-perform- ance liquid chromatography - immunoassays for drugs and metabolites in biological fluids.Moffat, 115. Metallic glasses: Applications of TMX in the study of -. Scott, 437. Metallurgy : Applications of thermodilatometry in Newall, 440. Fundamental studies of the application of an inductively coupled plasma to metallurgical analysis. Cave, Kaminaris, Ebdon and Mow- thorpe, 12. Metal pollution: The analytical chemist in studies of - in sediment cores. Farmer, 249. Methods development : Development and evaluation -. of new analytical methods-the work of the Analytical Methods Committee. Williams, 480. Development and testing of hydride generation methods for antimony and selenium in organic matter-the work of the Metallic Impurities in Organic Matter Sub-committee of the Analytical Methods Committee.Watson, 482. Micro-isoelectric focusing : Comparison of allergenic Microanalytical techniques: Comparison of micro- techniques of flame atomic-absorption spectro- metry (injection method, boat and cup system and platinum loop method). Berndt, 353. carbon profiling with the nuclear microprobe. Huddleston, Hutchinson and Pierce, 208. Microcomputer-based data-processing system for Use of the-in graphy. Smith, 158. extracts using -. Williams, McNulty and Deavin, 303. analytical chemistry. Braithwaite and Hen- thorn, 60. Mineral waters: Aspects of the chemical, medical the teaching of chromato- An introduction to __ and their application to and social history of __ and baths.Thorburn Burns, 463. Thomas Guidott (1638-1705) : physician and Microprocessors : See also Microcomputer. chymist, contributor to the analysis of -. Biography. Thorburn Burns, 2. absorption methods based on ~ using carbon rod electrothermal atomisation. Tyson and Stewart, 184. Multi-element analysis: Multi-element instrumental neutron activation analysis of human skin. Molybdenum heteropoly acids : Indirect atomic- Molokhia, Portnoy and Dyer, 160. mination of mycotoxins. Hunt, 471. Mycotoxins determination : Methods for the deter- N amounts of arsenic(V) and arsenic(II1) in natural waters by -. Orvini, Delfanti, Near infrared reflectance spectroscopy : See Spectro- scopy, near infrared reflectance. Neutron-activation analysis : Determination of trace Gallorini and Speziali, 237.Multi-element instrumental - of human skin. Molokhia, Portnoy and Dyer, 160. Radiochemical - of trace elements in sus- pended materials released from refuse incinera- tors. Gallorini, Orvini, Rolla and Burdisso, 199. ANALYTICAL PROCEEDINGS xii Nitrogen: Studies on the determination of low concentrations of - in gas streams. Baker and Headridge, 16. Bacon spectrometry for the analysis of -. Non-conducting materials: Spark source mass and Ure, 356. Nuclear fuel : Chemical and isotopic reference materials in the - cycle. Deron and Navra- Nuclear microprobe : Microcomputer-based data- processing system for carbon profiling with the til, 331.Nuclear magnetic resonance spectroscopy: See Spectroscopy, nuclear magnetic resonance. Huddleston, Hutchinson and Pierce, -. 208. 0 Obituary: 41, 53, 54, 183, 500. Optical emission spectroscopy: See Spectroscopy, Platinum loop flame atomic-absorption : Comparison optical emission. Optoacoustic spectroscopy: See Spectroscopy, opto- acoustic. Organic matter : Development and testing of hydride generation methods for antimony and selenium in--the work of the Metallic Impurities Sub-committee of the Analytical Methods Committee. Watson, 482. Brganic solvents: Ion-selective electrodes in -. Kakabadse, 255. Polarography : Degradation studies of penicillins Fogg, Fayad Jennings, 339. polychlorodibenzo-p-dioxins. of Organic vapour detection: Performance of a tube- type diffusive sampler for organic vapours in air.Brown and Walkin, 205. Osazone: A voltammetric study of the-of dihydroxytartaric acid. Jordan and Svehla, 243. Osibanjo, 0.: Biography, 55. Oxytocin assay: The assay of combined pharma- ceutical products by high-performance liquid chromatography. Pask-Hughes, Corran and Calam, 247. P Paint analysis : Applications of chromatography to the analysis of paints. Sansom, 393. Particle contamination standards : Implications of - for small-volume injections for the pharmaceutical industry. Spence, 522. Particle counting by Coulter Counter. Lines, 514. Air-borne and liquid-borne particle counters. Haslop, 519. The pharmacopoeial attitude on - in large- volume injectable solutions.Matthews, 525. Particles : The - of heavy metal smokes : bis- muth, lead, cadmium and zinc. Buckle and Tsakiropoulos, 73. Particle size analysis as a predictor of dissolution rate/bioavailability. Rubinstein, 5 12. Hard-sphere model for hydrodynamic chromato- graphy systems. Tavernier, Nies and Gijbels, 31. Particle counting by Coulter Counter. Lines, 514. Relevance and advantages of the Coulter Counter for standardisation and quality control of F iarmaceuticals. Spence, 509. R Butt, 100. Radiolabelling: The availability of iron in foods. Penir dlins: Degradation studies of - and Radioiodination: Techniques of -. cephalosporins using polarography. Fogg, Fayad and Martin, 211. Fairweather-Tait, 396.Polychlorodibenzo-p-dioxins determination: Deter- mination Baker, 478. Polymer matrix membranes: Development of ion- ments and their application to-. selective electrodes based on -. Hassan, Jones, Jones, Moody and Thomas, 241. Polymer systems : Dynamic mechanical measure- Wetton, 416. Research applications of dynamic mechanical analysis to polymeric systems. England, Long and Townend, 430. Polyurethane : Application of direct pyrolysis - mass spectrometry to the analysis of - and epoxy resins. Evans, 535. Potentiometric flow-through detectors: Flow injec- tion analysis : new analytical methods based on the use of potentiometric and spectrophoto- metric flow-through detectors. Hansen, 261. Potentiometry : Direct - for trace and ultra-trace analysis. Thomas, 350.Process instrumentation in the food factory. Steele, 489. Proteins : high-sulphur : Electrophoretic techniques used to study the heterogeneity of wool high- sulphur proteins. Sherrard and Speakman, 116. Publications received: 43, 88, 132, 174, 221, 271, 372, 403, 455, 548. Pyrolysis: Analytical potential of -- products derived from soil organic matter. Bracewell and Robertson, 532. Application of direct - - mass spectrometry to the analysis of polyurethane and epoxy resins. Evans, 535. Pharmaceuticals: Analysis of colouring agents in - by derivative ultraviolet - visible spectro- scopy. Fell and Allan, 291. Implications of particle contamination standards for small-volume injections for the pharma- ceutical industry. Spence, 522.Relevance and advantages of the Coulter Counter for standardisation and quality control of -. Spence, 509. Pharmacopoeia : The pharmacopoeial attitude on particle counting in large-volume injectable solutions. Matthews, 525. Plasma emission spectroscopy: See Spectroscopy, plasma emission. Plasma, inductively coupled : See Inductively coupled Plastics: Chromatography of -. Dawkins, 395. Platform . atomisation : Carbon furnace atomic emission using -. plasma. Marshall, Bezur, Fakhrul- Aldeen and Ottaway, 10. of micro-techniques of flame atomic-absorption spectrometry (injection method, boat and cup system and platinum loop method). Berndt, 353. and cephalosporins using -.and Martin, 211. Determination of trace amounts of organic substances by -. INDEX TO VOLUME 18 Rainwater analysis: Determination of Biscay Elejalde, atmospheric pollution by -. Gracia and Gurtubay, 192. Rank Hilger Spectroscopy Prize 1980: Awarded to M. R. Cave, 42, 87. Refractive index effect in flow injection analysis. Ham, 69. Retractometry : Studies on the determination of low concentrations of nitrogen in gas streams. Gallorini, Orvini, Baker and Headridge, 16. Refuse incinerators: Radiochemical neutron-activa- tion analysis of trace elements in suspended materials released from -. Rolla and Burdisso, 199. Research papers: Times to publication of --. Weston. (Editorial), 1. Rubber : Application of chromatographic methods in the - industry.Sewell and Mapperley, Royal Society of Chemistry awards: 233, 335, 402. 395. ~ S Safety in analytical laboratories. Hill. (Corre- spondence), 40. in analytical laboratories. Price. (Corre- spondence), 41. Sample handling for trace element analysis. Moody, Science and Engineering Research Council: SEKC 507. backs analytical science. Miller. (Editorial), Spectrometry, mass: Advances in evolved gas analysis. Barnes and Stephenson, 538. Application of direct pyrolysis - mass spectro- metry to the analysis of polyurethane and epoxy resins. Evans, 535. 337. Sampling and analysis of galvanising fume. Jack- son, Howe and Neuberger, 234. Sediment cores: The analytical chemist in studies of metal pollution in -.Farmer, 249. selenium in water treatment wastes. Elliott, Marshall and Smith, 64. Development and testing of hydride generation Analytical Methods Committee. Watson, 482. Sewage sludges: Aspects of the analysis of selenium Selenium determination: Aspects of the analysis of methods for antimony and selenium in organic matter-the work of the Metallic Impurities in Organic Matter Sub-committee of the in water treatment wastes. Elliott, Marshall and Smith, 64. Silver Medal: Awarded to A. C. Moffat, 229. tions. Thomas, 366. Small-volume injections: Implications of particle Small-sample NMR spectroscopy : scope and limita- contamination standards for - for the pharmaceutical industry. Spence, 522. Specific element detection in high-resolution gas Society for Analytical Chemistry: Silver Medal awarded to L.3. Kricka, 500. Silver Medal awarded to A. C. Moffat, 229. Soil: Analytical potential of pyrolysis products derived from I_ organic matter. Bracewell and Robertson, 532. Solid samples: Some novel applications of opto- acoustic spectroscopy to real samples. Ash- worth, Castleden and Kirkbright, 14. chromatography by plasma emission spectro- scopy. Uden, 189. Spectrometry, atomic-absorption: Applications of graphite furnace atomic-absorption spectro- metrv in clinical analvsis. Halls. 344. xiii Spectrometry, atomic-absorption-continued Comparison of detection limits in magnetically induced optical rotation and atomic-absorption spectroscopy. Kersey and Dawson, 187.Comparison of micro-techniques of flame atomic- absorption spectrometry (injection method, boat and cup system and platinum loop method). Berndt, 353. Determination of mercury vapour in laboratory atmospheres. Emslie, Kaseke and Tyson, 67. Determination of tetraalkyllead compounds in environmental samples by gas chromato- graphy - graphite furnace atomic-absorption spectrometry. Chakraborti, Jiang, Surkijn, De Jonghe and Adams, 347. Flow-injection techniques in atomic-absorption spectrometry. Tyson, 542. Indirect atomic-absorption assay of epoxide hydrolase activity and determination of 1,2- diols via digested lead periodate. Tan and Melius, 384. Tyson and Indirect atomic-absorption methods based on molybdenum heteropoly acids using carbon rod electrothermal atomisation.Stewart, 184. Safety in analytical laboratories. Hill. (Corre- spondence), 40. Safety in analytical laboratories. Price. (Corre- spondence), 41. atomic emission using platform atomisation. Marshall, Rezur, Fakhrul-Aldeen and Ottaway, Spectrometry, 356. ultraviolet - visible : Analysis of colour- Spectrometry, atomic emission : Carbon furnace 10. Spectrometry, Auger electron : Analytical aspects of gas-phase Auger electron spectrometry. Tyson, 120. Spark source mass spectrometry for the analysis of non-conducting materials. Bacon and Ure, ing agents in pharmaceuticals by derivative ultraviolet - visible spectroscopy. Fell and Allan, 291. Spectrophotometric flow-through detectors: Flow injection analysis : new analytical methods based on the use of potentiometric and----.Hansen, 261. Spectroscopy, near infrared reflectance : Application Spectroscopy, luminescence: Luminescence spectro- scopic analysis of coal hydrogenation liquids. Kershaw, 155. of near infrared reflectance spectroscopy to the analysis of food. Osborne, 488. Spectroscopy, optical emission : Fundamental studies Spectroscopy, nuclear magnetic resonance : Analysis of fossil-fuel extracts by NMR spectroscopy. Jones and Bartle, 362. Conformational and structural studies by lanth- anide-induced shifts. Abraham, 364. Small-sample NMK spectroscopy : scope and limitations. Thomas, 366. of the application of an inductively coupled plasma to metallurgical analysis.Cave, Kaminaris, Ebdon and Mowthorpe, 12. of optoacoustic spectroscopy to real samples. Spectroscopy, optoacoustic : Some novel applications Ashworth, Castleden and Kirkbright, 14. xiv ANALYTICAL PROCEEDINGS Spectroscopy, plasma emission: Specific element Structural studies: Conformational and - by detection in high-resolution gas chromato- graphy by plasma emission spectroscopy. Uden, 189. Sport: Doping in - and some methods for its control. Beckett, 114. Steel: Applications of thermodilatometry in nietal- lurgy. Newall, 440. Studies on the determination of low concentra- tions of nitrogen in gas streams. Baker and Headridge, 16. lanthanide-induced shifts. Abraham, 364. Synthetic fibres: Thermal stress properties of -.Ogilvie, 426. of T Teaching: Use of the microcomputer in the ~ chromatography. Smith, 158. Thermal volatilisation analysis: Applications of -. Tetraalkyllead compounds: Determination of - Tube-type diffusive sampler : Performance of a - in environmental samples by gas chromato- graphy - graphite furnace atomic-absorption spectrometry. Chakraborti, Jiang, Surkijn, De Jonghe and Adams, 347. Textile defects: Laser microprobes and the analysis of -. Ogilvie, 117. Therapeutic drugs: Measurement of - in a busy Thermal analysis : Advances in evolved gas analysis. Barnes and Stephenson, 538. clinical laboratory. Toseland, 391. Ogilvie, 426. McNeill, 540. lurgy. Newall, 440. glasses.Scott, 437. Thermal stress properties of synthetic fibres. -. Thermodilatometry : Applications of - in metal- Applications of - to ceramic science. Morrell, Applications of TMA in the study of metallic Introduction to thermomechanical methods. 443. Daniels, 412. Thermomechanical analysis and its applications. Barton, 421. -of zeolites. Dyer, 447. Applications of TMA in the study of metallic glasses. Scott, 437. Daniels, 412. braid analysis to the cure and properties of Gillham, 424. Thermomechanical methods: See also Thermo- mechanical analysis. Thermomechanical methods : Introduction to -. Thermosetting systems : Application of torsional Times to publication of research papers. Weston. (Editorial), 1. -. Thin-layer chromatography: See Chromatography, t hin-layer. Application of torsional braid analysis to the cure and properties of thermosetting systems. Gillham, 424. Time - temperature transformation diagrams : TMG award: Awarded to E. Paterson, 230. Torsional braid analysis: Application of - to the cure and properties of thermosetting systems. Gillham, 424. Touch-stone: A - for gold and silver wares. Thorburn Burns, 146. air. Toxic substances: Application of electrochemical detection in high-performance liquid chromato- graphy to the measurement of -in Purnell and Warwick, 151. Design of laboratories for handling -. Gibbons and Davies, 467. Disposal of small amounts of - from the laboratory. Cook, 468. Trace analysis: Anatomical variations of trace metal levels in air. De Antonio, Katz, Scheiner and Wood, 162. Determination of trace amounts of organic substances by polarography. Jennings, 339. Direct potentiometry for trace and ultra-trace analysis. Thomas, 350. Introductory lecture (Trace and ultratrace analysis). Belcher, 336. Sample handling for trace element analysis. Moody, 337. Training of analytical chemists. Pitt. (Corre- spondence), 87. Tributyltin fluoride: The bioassay and analysis of Sherman and Hoang, 196. for organic vapours in air. Brown and Walkin, 205. Turner, Edward: Edward Turner (1796-1837) and the Atomic Weight Controversy. Biography. Campbell, 381. Ultraviolet - visible spectroscopy: See Spectrometry, U Urinary metabolites : Gas chromatographic profiling of - of ethynodiol diacetate. Lewis and V Voltammetry: is it worth considering? Fogg, 387. A voltammetric study of the osazone of di- hydroxytartaric acid. Jordan and Svehla, W Waste chemical disposal: Disposal of small amounts of toxic substances from the laboratory. ultraviolet - visible. Vose, 253. 243. Cook, 468. Waters: See also Estuarine waters. Determination of trace amounts of arsenic(V) and arsenic(II1) in natural - by neutron- activation analysis. Orvini, Delfanti, Gallorini and Speziali, 237. Elliott, Marshall and Smith, selenium in -. Z Zeolites : Thermomechanical analysis of -. Water treatment wastes: Aspects of the analysis of 64. Wool: Electrophoretic techniques used to study the heterogeneity of - high-sulphur proteins. Sherrard and Speakman, 116. Dyer, 447. Zinc: The particles of heavy metal smokes: Buckle bismuth, lead, cadmium and -. and Tsakiropoulos, 73.

ISSN:0144-557X    

DOI:10.1039/AP98118BA001

出版商:RSC    

年代:1981

数据来源: RSC

摘要:

2 THOMAS GUIDOTT (1638-1705) Anal. Proc. Thomas Guidott (1638-1705): Physician and Chymist, Contributor to the Analysis of Mineral Waters Guidott is of some interest to the history of analytical chemistry in that his two major works, “A Discourse of Bathe and the Hot Waters There” (1676)l (Figs. 1 and 2) and “Thermis Britannicis” (1691)2 (Figs. 3 and 4), bracket Boyle’s important “Short Memoirs for the Natural and Experimental History of Mineral Waters” (1 684/5)3; he also was responsible for the Third Edition of E. Jorden’s “Discourse of Xatural Bathes and Mineral Waters.”* Bibliographic material on Guidott is based on Wood’s “Athenae O X O ~ ” ~ and “Life and Times,”6 Hearne’s collection^"^ and the “Register of Wadham College”s; these are summarised with a list of Guidott’s principal publications in the “Dictionary of National Bi~graphy.”~ Guidott was born a t Lymington, Hampshire, in September 1638; he was the eldest son of Francis Guidott and the great- great-grandson of Sir Anthony G ~ i d o t t i .~ He was educated in grammar learning a t Dorchester under Mr. S. Crumbleholme and became a commoner of Wadham College, Oxford, in 1656.8 He graduated BA 1659 and MA 1662. He then took to medical studies and was admitted MB in 1666; in 1664 he declined an offer t o go to Copenhagen to study anatomy under Thomas Bartholine. He practised in Oxford for 1 year, then removed to Bath where Dr. John Maplet, a noted physician of that place, helped him to attain an extensive practice, most of which he had lost by 1679 by his impudence, lampooning and libelling.5 Guidott had been a lively undergraduate and his record shows8 he was taken up by Bursar Lloyd for Battels, 8th July 1669.He retired to London in 1679, in the summers visiting Bath. In 1671 he performed his exercise a t Oxford for the degree of MD but did not graduate. He declined the Chair of Physic at Venice and at Leyden in 1690. Wood was in regular correspondence6 with Guidott and appears to have known him well, describing him as “a person of good parts, well vers’d in Greek and Latin learning, and intelligent in his pro- fession, but so much overwhelm’d with selfJanuary, 1981 THOMAS GUIDOTT (1638-1705) 3 conceit and pride as to be sometimes crazed, especially when his blood was heated with too much bibbing.” The date of his death is sulphur anions.uncertain-he was alive in 1698 a t Bath; Hearne’ refers to Guidott in an entry dated 10th December 1705, “Dr Tho. Guidott an ingenious (but vain, conceited, whimsical) Physition a t ye Bath, amongst other Books published Theophilus de urinislO out of a MSt in the Bodlejan Library, and never had ye Civility to send a copy to ye Library, as he was oblig’d to do.” This may have been written as a sharp epitaph. His last published work appears to be 1705.11 Guidott was not that unkind to his almu muter: he donated books to Balliol College in 169412 and was known to members of the Philosophical Society of Oxford,13 a forerunner of the Royal Society. In 1694 he also repaid his debt to Maplet by seeing through the press Maplet’s14 posthumous “Epistolarum Medicarum . .. .” in recognising the true nature of salts and in particular had problems in the speciation of Fig. 2. Frontispiece of “Discourse . , .,” 1676, engraved by F. H. Van Hove (b. Hague, 1626; d. London, 1698). Guidott considered the Bath water to contain eight distinct substances, nitre, common salt, vitriol, bitumin, sulphur, freestone, marl and ochre,2 which were “to be the business of the first book of my treatise ‘De Thermis Bathonienfibus’ . ” The term nitre was used a t the time to describe a variety of bright, shiny salts, some of which were characterised by additional names, e.g., saltpeter. Guidott was ’sure his nitre was not saltpeter, nor was it completely like the “nitre of the ancients,” i.e., crude sodium carbonate. After purification by calci- nations and dissolutions he obtained a sal umuyum, a bitter purging salt, i.e., magnesium sulphate, although it retained some alkaline properties.The shooting crystallisation into needles and the taste were the main factors Fig. 1. T. Guidott, 1676. used to differentiate it from other nitres. The potential confusion from the use of the term Guidott’s chemical merit must be viewed nitre continued well into the eighteenth century; Short15 uses the term for what can only be calcium carbonate, Charleton16 calls against the state of knowledge a t the time; like other chemists a t this period he had problems4 THOMAS GUIDOTT (1638-1705) Anal. Proc. magnesium sulphate “calcarious nitre,” as did Lister earlier.20 Guidott was sure that Bath water was not aluminous and he was also explicit that “artificial alom will not with Galls strike a purple colour, but natural alom with its inbred Ochre will; ascribing more to the Ochre than the Alom.” He was aware of the simi- larities between alum and vitriol and that the gall test allowed a distinction, a clear discussion of reagent selectivity.Vitriol was recognised by the gall test, but recent work indicates that the iron is mainly present as suspended matter1’ and hence to be considered with 0chre.l The idea that bitumen was present, also considered by Boyle as a possible constituent of mineral waters, arose from floating brown masses present in the summer which were combustible when dry; the material was a moss.16y18 The freestone was the non-saline gritty residue, which “leaves a white colour like chalk on the fingers after part of which dissolved with ebullition in acid.” Guidott was in advance of Boyle in his con- sideration of residues or sediments formed after evaporation.These were separated into saline and non-saline, and he sent samples to Willis for examination, an early carefully recorded example of collaborative analysis. Sulphur was a problem to the early mineral water analysts and indeed the cause of much controversy a t Scarborough Spaw between Wittie and Simpson15 and early came to the attention of the Royal Society.lg Boyle wrote his “Memoirs . . .”3 a t the time of the con- troversy on sulphur in mineral waters, which may be why “he purposely forbore to consult the authors which had professedly written upon Medical waters .. . his design did not require that he should transcribe from them.” He did, however, commend Dr. Lister’s, “De Fontibus Medicatis Angliae”20 and “the curious little Tract of the French Mineral Waters21 . . . whereby they curiously examine the Saline and earthy Residences of Waters, which our author has not done . . .,” as was done earlier by Guidott. Guidott well aware of Wittie’s problems and was careful not to commit himself on the question of sulphur; he considers that sulphur is probably incorporated with the salt, identi- fication would be difficult “unless a separation of the sulphur from the salt be made, which, I presume is not easy to be done, without the help of fire by the sulphur is consum’d.” He did not separate the sulphur, “being not apart but residing in a salino-sulphurious salt.” He was aware of the blackening of silver as a test for sulphur but only obtained a slight colora- tion after some time with Bath water.He was “not ignorant” of methods of dissolving elemental sulphur in alkalis and properties of the solution, and not fully satisfied that the addition of acid is the best or only precipitator of sulphur; other constituents such as alum may precipitate. Guidott extracted the salts from Bath water for sale, as noted in a letter to Sir Edward Greaves22 in which he also acknowledges he was assisted in his studies by Mr. Henry Moore, an “expert Apothecary and Chymist of this City.” This extraction of the salts was a t least 5 years before Nehemiah Grew exhibited “bitter purging salt” to the Royal Society .23 Guidottl , 2 criticised MayowZ4 on Bath waters as “a novel writer,” “who hath ploughed with my Heifer,” yet he accepted most of Mayow’s results. Short15 later supports Guidott’s criti- cism of Mayow, regarded Guidott as “a writer of superior note and diligence,” but disagreed with him on the nature of nitre and sulphur in water and also regarded many of Guidott’s arguments as inconclusive. Guidott was, I feel, correct in his caution; it is difficult to extract elemental sulphur from sodium/magnesium sulphate. In addition to items already discussed, “Discourse” contains a “Century of Observa- tions” [Observationes Hydrostaticae, Chroma- Fig. 3. T. Guidott, 1691.January, 1981 THOMAS GUIDOTT (1638-1705) 5 ticae and Miscellaneae (Figs.1-3). The colour observations (XXI-LX) all concern the gall test, the miscellanea (LXI-C) contain quantitative results] and the lives and character of the Physicians of Bathe (17 in all, including Jorden4 used by, for example Freeman, in later accounts of Bath25) and concludes with a poem on Sonierschall, “a chymist of note, or more correctly an alchemist since he was aim’d to pave the streets of Bathe with gold.” Guidott’s alchemical sympathy is also shown in the Frontispiece to “Thermis” (Fig. 4). In the Preface Guidott recommends the keeping of a Register of cures; this was included in “Thermis’’2 and also extended and published separately,26 and reprinted later.27 Fig. 4. Frontispiece of “Thermae . . .,” 1691, engraved by D. Loggan (b. Danzig, 1633 or 1635; d .London, 1692). This plate is of alchemical significance. Pallas is Pallus Athene or Minerva, who was held in high esteem by alchemists as the forceful goddess of wisdom. Alcides was the earliest name for Hercules before he was renamed by the Delphic oracle, the operations of the Great Work, i.e., transmutations, were likened to the tasks of Hercules. The surround to the title alludes to Hermes Trismegistos, the patron of alchemy and alleged father of the Hermetic Art; above is the Tetragrammaton, the sacred unpronounceable Jewish word for God. The Paracelsians considered that the true chemical philosopher learns through Divine revelation as well as by chemical experimentation. Guitlott wrote to Boyle28 with regard to the Gall test, praised Boyles “Memoirs .. .” and referred to his discourse in Latin on mineral waters he had almost completed. “Thermis” is more general than “Discourse” in that it discusses baths and mineral waters such as those at Buxton, Scarborough, Tunbridge and Islington, is more fully referenced and gives a usefully argued account of the contents of mineral waters, but contains little new quanti- tative data over that in “Discourse.” Guidott was aware of all the early European writers, probably by editing Jorden’s work; in “Thermis” particular note is given (numbers of citations in parentheses) to the works of Boyle3 (lo), Jorden* (24), Lister20 (9), Duclos21 (10) and French29 (14), and one plate is dedi- cated to Boyle. Guidott’s treatises relating to the city and waters of Bath were reprinted by Chapman,30 whilst in London Guidott wrote an account of Sadler’s WelPl; these wells were also examined by B ~ y l e .~ Guidott was also the author of some harsh epitaphs,6 lampoons circu- lated as broadsheets under pseudonyms such as E. Philander, P h i l o m ~ s u s . ~ ~ He also had a serious side as evidenced by his notes on biblical criticism sent to P ~ o l e ~ ~ and some of his un- published material left in man~script.~ In conclusion, Guidott is an overlooked, careful, colourful chemical physician, spagyrist or chymist who was in advance of many in his times. References 1. Guidott, T., “A Discourse of Bathe, and the Hot Waters There, also Some Enquiries into the Nature of the Water of St. Vincent’s Rock, near Bristol; and that of Castle-Cary. To Which is Added, a Century of Observations, more fully declaring the Nature, Property and Distinction of the Baths.With an account of the Lives and Character of the Physicians of Bathe,” H. Brome, London, 1676. 2. Guidotti, T., “ Anglo-Britanni, De Thermis Britannicis Tractatus Accesserunt Observa- tione Hydrostaticae, Chromaticae, Miscel- laneae,” F. Leach, Londini, 1691. 3. Boyle, R., “Short Memoirs for the Ex- perimental History of Mineral Waters. Addressed by way of Letter to a Friend.” S. Smith, London, 1684/5 (for a review, see Phil. Trans., 1685, 15, 1063). 4. Thorburn Burns, D., “Edward Jorden MD (1569-1632) : Early Contributions to Solu- tion Analysis,” Proc. Anal. Div. Chem. Soc., 1979, 16, 219. 5. Wood, A. W., “Athenae Oxonienses,” New Edition, P. Bliss, London, 1820.6. Clark, H., Editor, “The Life and Times of Anthony Wood, Antiquary of Oxford, 1632-1695, Described by Himself,” Volumes I-IV, Oxford Historical Society, Clarendon Press, Oxford, 1891-95.7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. Subscription rates for 1981 (with indexes) Analytical Proceedings alone: f 30.00 (UK/Eire) ; $70.50 (USA) ; f31.50 (Rest of world) Analytical Proceedings with The Analyst and Analytical Abstracts: fl90.00 (UK/Eire) ; $471.50 (USA) ; f200.50 (Rest of world) Subscriptions should be sent to : The Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts., SG6 1 HN, England I Doble, C. E., Editw, “Remarks and Collec- tions of Thomas Hearne,” Volume I, Oxford Historical Society, Clarendon Press, Oxford, 1885.Gardiner, R. B., “The Registers of Wadham College,” G. Bell & Sons, London, 1889. Goodwin, G., in Stephen, L., and Lee, S., Editors, “Dictionary of National Bio- graphy,” Volume 23, Smith, Elder and Co., London, 1890 [available in compact (micrographic) edition, Oxford University Press, London, 19751. “Theophili de urinis libellus.” T. Guidotius . . . “Mendas sustutit . . . de novo verit, et notas . . .” Lugduni Batavorum, 1703. Guidott, T., “An Apology for the Bath, Being an Answer to a Late Enquiry (by Sir J. Floyer) into the Right Use and Abuses of the Baths in England . . .,” G. Sawbride, London, 1705. Gunther, R. T., “Early Science in Oxford,” Volume XI, “Oxford Colleges and Their Men of Science,” Oxford, 1937. Letter from E. Tyson to Dr.Plot in ref. 12, Volume XII, “Dr Plot and the Corre- spondence of the Philosophical Society of Oxford.” Maplet, J., “Epistolarum Medicarum speci- men de thermanum Bathonensium effec- tis . . .,” Edente T. G., London, 1694. Short, T., “The Natural, Experimental and Medicinal History of the Mineral Waters of Derbyshire, Lincolnshire and Yorkshire, Particularly those of Scarborough . . . To Which are Added, Large Marginal Notes, Containing a Methodical Abstract of all those Treatises Hitherto Published on These Waters . . .,” F. Gyles, London, 1734 (contains extensive abstracts of most of the material relevant to the Wittie- Simpson controversy which came to the attention of the Royal Society, ref. 19). Charleton, R., “A Treatise on the Bath Waters : Wherein are Discover’d The Several Principles of Which they are Compos’d .. .,” T. Boddely, Bath, 1754. Riley, J . P., J . AppZ. Chem., 1961, 11, 190. Ray, J . (Raio, J .), “Synopsis Methodica Stirpium britannicarum . . .,” S. Smith, London, 1690 (later edition, edited by J . J . Dillenins, W. Innys and J . Innys, London, 1724). Foot, D., Phil. Trans., 1669, 4, 1050. 6 THOMAS GUIDOTT (1638-1705) Anal. Proc. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. Lister, M., “De Fontibus Medicatis Angliae,” W. Kettilby, Londini, 1684. Duclos, S. C., “Observations on the Mineral Waters of France,” H. Faithorne and J. Kersey, London, 1684 (for a detailed review of original edition, 1675, see Phil. Trans., 1676, 11, 612). Guidott, T., “A Letter Concerning Some Observations Lately Made at Bath : Written to his Much Honoured Friend Sir E.G.” ( i e ., Edward Greaves, knight and baronet MD in London), H. Brome, London, 1674. This is included in “Dis- course . . .” (ref. 1). Coley, N. G., Med. Hist., 1979, 23, 191. Mayow, J., “Tractatus Quinque Medico- Physici. Quorum Primus Agit de Sal Nitro . . .,” Oxon. ii, Sheldoniano, 1674. Freeman, H. W., “The Thermal Baths of Bath . . .,” Hamilton, Adams & Co., London, 1888. Guidott, T., “The Register of Bath or Two Hundred Observations Containing an Account of Cures Performed and Benefit Received by the Use of the Hot Waters of Bath . . .,” F. Leach, London, 1694. Quinton, J., “A Treatise of Warm Bath Water,” Volume 11, Oxford, 1734 (includes Guidott’s “Register . . .”). Guidott, T., to R. Boyle, Bath, October 14 1685, in “The Works of the Honourable Robert Boyle,” Volume 6, W. Johnston et al., London, 1772, p. 662. French, J., “The York-Shire Spaw, or a Treatise of Four Famous Medicinal Wells, . . . Together with the Causes, Vertues and Use Thereof,” E. Dod and N. Ekins, London, 1652; reprinted Halifax, 1760. Chapman, H., “A Collection of Treatises Relating to the City and Waters of Bath . . .,” J. Leake, London, 1725. T. G.(uidott), “A true and Exact Account of Sadlers Well,” 1684. “Gideon’s Fleece: or Sieur de Frisk.” An Heroick Poem. Written on the Cursory Perusal of a Late Book Call’d The Conclave of Physicians by a Friend of the Muses, S. Smith, London, 1684. Poole, M., “Synopsis Criticorum Aliorumque S. Scripturae Intrepretum . . .,” Volumes I-IV, C. Bee, London, 1669-76 (Guidott’s material is acknowledged in Volume I). D. THORBURN BURNS Notice to Subscribers

ISSN:0144-557X    

DOI:10.1039/AP9811800002

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年代:1981

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RSC ANALYTICAL DIVISION SCOTTISH REGION A meeting on CLINICAL AND BIOLOGICAL DEVELOPMENTS IN HPLC to be held a t The University of Edinburgh on February 17th and 18th, I981 This meeting is to be organised jointly with the Chromatography and Electro- phoresis and Joint Pharmaceutical Analysis Groups and the Association of Clinical Biochemists. It will consist of reviews of progress in detector tech- nology, sample pre-treatment, pharmaceutical research and therapeutic monitoring, together with discussion seminars on ion-pair method design, industrial R and D preparative scale HPLC and related topics. For further details of the meeting, contact Mr. A. F. Fell, Department of Pharmacy, Heriot-Watt University, 79 Grassmarket, Edinburgh, EHI 2HJ.

ISSN:0144-557X    

DOI:10.1039/AP98118BX003

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年代:1981

数据来源: RSC

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January, 1981 RESEARCH AND DEVELOPMENT TOPICS 7 Research and Development Topics in Analytical Chemistry The following are summaries of seven of the papers presented at the Research and Develop- ment Topics in Analytical Chemistry Meeting of the Analytical Division held'on April 1st and 2nd, 1980, at the University of Kent at Canterbury. Summaries of five other papers were published in the December, 1980, issue of Analytical Proceedings (p. 533). A Systematic Investigation of the COD Test for Estuarine Waters C. Southway and L. S. Bark Department of Chemistry and Applied Chemistry, University of Salford, Salford, M5 4WT Introduction The chemical oxygen demand (COD) test is a chemical means of determining the chemically oxidisable organic content of a sample of water. Basically, the test consists in determining the amount of oxidising agent reduced by the water sample under certain standard conditions.The results are calculated in terms of the oxygen equivalent of the oxidising agent reduced and are expressed as milligrams of oxygen per litre of sample. Ideally, all organic com- ponents should be oxidised to carbon dioxide and water, with nitrogen from amines and amino compounds being converted into the ammonium ion and hence not being oxidised. The results of the COD test are considered to be a measure of the gross organic pollution of a water sample and are used for various purposes; for example, in determining the effective- ness of a wastewater treatment process or for monitoring pollution levels. They may in turn be used as a basis for the calculation of charges to industry for trade-effluent discharges to sewers and water courses.Chemical oxygen demand tests have been used since the late nineteenth century,lq2 since when many oxidising agents have been used under many different conditions.3-* A t present, the most commonly used oxidising agent is potassium dichromate, which is used in several standard meth~ds.~-ll There is not, however, any single, universally accepted standard method, although the methods used are modifications of a method proposed in 1949.12 They consist in heating the water sample under reflux with a mixture of potassium dichromate and sulphuric acid for a specified time. Silver(1) sulphate is added, as silver(1) ions promote the oxidation of many organic compounds, which would otherwise be only partly oxidised; this applies especially to acetic acid, which is formed as an oxidation product of many organic compounds.The excess of the dichromate is determined either titri- metrically or spectrophotometrically. Many modifications to the standard methods have been proposed, several of which have been concerned with removing the interference caused by the presence in the sample of chloride ions. However, no completely satisfactory answer to the chloride interference has yet been found. Chloride Interference Inorganic reducing agents are also oxidised in the COD test, the most troublesome being chloride. As it is resistant to biological oxidation, inorganic chloride is not generally con- sidered part of the oxidisable load of a water sample. However, it is oxidised under the conditions of the standard COD tests, although this in itself would not be a problem if there were not any organic materials present, because if the chloride concentration is known then the dichromate reduced by the chloride can be accounted for.The problem arises because of interactions between chloride or chlorine and some of the organic compounds in the sample. This is especially so with nitrogen-containing compounds. The interaction may occur via the formation of chloramines or nitrogen trichloride, vix: RNH, -+ NH, + CO, + H,O NH,+ + 3C1, -+ NC13 + 3C1- + 4H+ h v 2NC1, --f N, + 3C1,8 RESEARCH AND DEVELOPMENT TOPICS Anal. Proc. in a cyclic process whereby chloride is being regenerated from chlorine and then being re- oxidised to chlorine.Also, the addition of silver(1) sulphate causes precipitation of silver chloride which, in the presence of organic compounds, is neither completely nor reproducibly oxidised. The over-all effect of the interference is apparently to increase the COD of the sample, especially in samples of high chloride concentration but low organic content, such as are found in estuarine waters. In samples containing an appreciable amount of chloride, the validity of the results of the COD test may be in doubt. This is of concern, particularly in instances where the test results are used as the basis for charging for industrial wastewater disposal to sewers, in which cases the costs involved may be considerable. As a result of this a method is needed wherein the chloride interference is eliminated by preventing the concurrent oxidation of organic material and chloride.This can be effected in two ways: either (i) by leaving the chloride in the test mixture but preventing its oxidation, or (ii) by removing the chloride prior to the COD test. Both ways have been used in previously reported attempts to remove chloride interference. Three methods have been used in attempts to prevent chloride oxidation: masking with mercury( II)l3?l4 ; precipitation of chloride using silver( I) l5 ; or altering oxidation conditions.16 Two methods have been used for removal of chloride, the chloride being removed as hydrogen chloride2 or as chlorine.lsY1* In effect, the ammonium ion is being oxidised to nitrogen. Current Investigations Three processes for the removal of chloride from the test solution have been investigated.(i) Removal by precipitation as silver chloride with subsequent filtration, in such a manner that a negligible amount of organic matter is co-precipitated with the silver chloride. (ii) Removal as chlorine in an oxidation stage, mild enough to prevent any significant oxidation of easily oxidised organic matter. (iii) Removal by a ligand exchange process. Rapid precipitation of silver chloride by addition of a silver salt to a chloride solution results in a colloidal precipitate that is likely to have associated co-precipitated impurities. However, if the precipitate is formed in a precipitation from homogeneous solution process (that is, the silver ions are generated at a controlled rate in the solution) then the problenis of co-precipitation will be greatly reduced.Therefore, the precipitation of silver chloride using electrochemically generated silver ions from a silver anode has been investigated. By controlling the current and the anode geometry, the rate of production of silver ions can be controlled to produce a pure precipitate free from any occluded matter. The precipitated silver chloride can be filtered before the sample is subjected to the COD test. A preliminary filtration of the sample prior to the precipitation is necessary to prevent loss of particulate organic matter during the silver chloride filtration. Some preliminary investigations have been carried out using sodium chloride solutions to determine the precipitation efficiency and the necessary conditions. I t was found necessary to separate the anode and the cathode with a glass frit and to acidify the solution to prevent formation of silver oxide or hydroxide rather than silver chloride.The acid concentration around the cathode was not critical; however, that around the anode, was important, because if it was too low (less than about 6 M in sulphuric acid, depending on the rate of stirring) the silver chloride formed an adherent coating around the anode, preventing further precipitation. The efficiency of the process was determined by measuring the amount of electricity con- sumed by the silver ion generating cell, using a coulometer, and comparing this with the value expected from the mass loss of the anode during the generation process.It was found that in all instances the efficiency was less than lOOyo and not reproducible; values ranged between approximately 50 and 90%. The second method investigated was the removal of chloride by oxidation to chlorine under relatively mild conditions compared with those in the standard tests (cf., reference IS). As both temperature and acid concentration affect the oxidising power of dichromate, lower temperatures and lower acid concentrations were used. A stream of nitrogen wasJanuary, 1981 RESEARCH AND DEVELOPMENT TOPICS 9 used to remove the chlorine as soon as it was produced. It was hoped that in this way the chloride might be completely removed or its concentration brought to an acceptable level without interactions with organic material.(The level at which the chloride concentration is deemed “acceptable” depends on the composition of the sample and also its organic carbon concentration.) The percentage of chloride removed varied inversely with the chloride concentration, and directly with the reaction time; however, there is a practical limit to the time available for this stage. Increasing the acid concentration also led to an increase in the percentage of chloride removed; however, as the purpose is to oxidise chloride under “mild” conditions, and the oxidising power of dichromate depends on the acid concentration, it was decided to limit the acid concentration to a maximum of 50% V/V (the concentration used in most standard COD tests) .9-11 The third method investigated has been the removal of chloride in a ligand exchange process,lg which is a more selective process than ion exchange.It was thought that it might be possible to remove inorganic chloride without removing organic anions, which would be removed preferentially by most anion exchangers. Poly(viny1pyridine) resins are currently being used in these investigations, in either the silver(1) or mercury(I1) form. So far, investigations have shown that the poly(4-vinyl- pyridine) resin has a greater affinity for the metals than has the poly(2-vinylpyridine) resin, and forms stronger metal - resinate complexes, and also that the mercury(I1) complexes are more stable than their silver(1) counterparts. Both silver(1) and mercury(I1) resinate complexes remove chloride from solution ; how- ever, investigations have not yet been completed although preliminary work indicates that the method has potential use.The amount of chloride that can be removed is reasonable, and the loss of organic matter is apparently zero. Considerations of cost may be an important factor in this part of the investigation. Under the conditions used it was not possible to remove the chloride completely. One of us (C.S.) would like to acknowledge the provision of a grant from the Department of the Environment, which enabled this work to be done. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. References Kubel, W., 2. Anal. Chem., 1867, 6, 252. Frankland, E., and Armstrong, H. E., J . Chenz. SOC., 1868, 21, 77. Adeney, W. E., and Dawson, B.B., Sci. Proc. R. Dublin Soc., 1926, 18, 199. Johnson, D. W., and Halvorson, H. O., J . Bacteriol., 1941, 42, 145. Flay, K. B., Sewage I n d . Wastes, 1953, 25, 953. Leibnitz, E., Behrens, U., Kroll, H., and Richter, H., Chem. Tech. (Berlin), 1962, 14, 33. Le Coq, H., Chim. Anal. (Paris), 1957, 39, 232. Schulze-Rettmer, R., and Sraten, G., 2. Wasser Abwasser Forsch., 1974, 7, 57. North West Water Authority, “Determination of Chemical Oxygen Demand (Dichromate Value) of Polluted and Waste Waters,” Scientific Services SCA 53/R2, 1977. Department of the Environment, “Analysis of Raw, Potable and Waste Waters,” HM Stationery Office, London, 1972, pp. 121-122. American Public Health Association, American Water Works Association and Water Pollution Control Federation, ‘Standard Methods for the Examination of Water and Wastewater,” Thirteenth Edition, American Public Health Association, New York, 1971, pp.495-499. Moore, W. A., Kroner, R. C., and Ruchhoft, C. C., Anal. Chern., 1949, 21, 953. Dobbs, K. A4., and Williams, R. T., Anal. Chem., 1963, 35, 1064. Cripps, J . M., and Jenkins, D., J . Water Pollut. Cont. Fed., 1964, 36, 1240. Zietz, U., Gus Wasserfach, Wasser-Abwasser, 1976, 117, 181. Ryding, S.-O., and Forsberg, A., Water Res., 1977, 11, 801. Cameron, W. M., and Moore, T. B., Analyst, 1957, 82, 677. Hoffmann, H.-J., LaborPrux. (Wurzberg), 1979, 3, 38. Helfferich, F., Nature (London), 1961, 189, 1001.10 RESEARCH AND DEVELOPMENT TOPICS Anal. Proc. Carbon Furnace Atomic Emission Using Platform Atomisation J.Marshall, L. Bezur, R. Fakhrul-Aldeen and J. M. Ottaway Department of Pure and Applied Chemistry, Unizfersity of Strathclyde, Cathedral Street, Glasgow, G1 1XL Carbon furnace atomic-absorption spectrometry (CFAAS) is now a well established technique in trace metal analysis. Recent work has investigated the potential of the carbon furnace as an emission source, and detection limits considerably lower than 1 pg ml-l have been reported for more than 40 elements1 using direct atomic emission rather than absorption measurement. Design factors inherent in commercial atomic-absorption instruments used for such measure- ments have, however, limited the development of CFAES, both in terms of absolute sensitivity and in its application to the analysis of real samples. Compared with other emission sources, the carbon furnace operates at a relatively low temperature (- 3200 K maximum). This is advantageous from the point of view that fairly simple spectra are obtained.However, a continuum background is present at all times during the measurement of furnace emission signals and has been shown to result from Rayleigh scattering of tube wall radiation by atoms or molecules in the vapour phase of the furnace.2 This background can be measured separately and manually subtracted from the analyte signal, but this is only satisfactory where the background remains relatively constant. This is not the case for real analysis where the background will vary with time, matrix composition and from sample to sample. Wavelength modulation provides an efficient automatic method of correction for such a continuum background.A rotating quartz mechanical chopper, which has been described el~ewhere,~ was used to achieve a square-wave modulation waveform for this work. By using chopper blades of different thicknesses of quartz, it is possible to refract the light by different amounts. Thus, the background signal can be measured at both sides of the atomic line by a suitable refraction, and the average value can then be subtracted from the total signal (signal plus background) measured at the wavelength of the atomic line, giving the net emission signal. It is well established that the atomic-emission signal from a furnace is delayed with respect to the atomic-absorption ~ i g n a l . ~ However, the temperature at the time of the peak emission signal is still, for most elements, well below the maximum temperature of the furnace, and it would be desirable to delay the atomisation of the sample until a higher temperature is achieved.Platform atomisation would appear to be well suited to this purpose. The technique of platform atomisation in CFAAS has been investigated by a number of workers5-* The sample is placed on a thin pyrolytic graphite plate, which is located in the tube beneath the injection port. This platform has poor thermal contact with the tube itself, and there is a time lag in the heating of the platform which results in a delay in the atomisation of the sample. Atomisation from a platform effectively shifts the occurrence of higher atom populations to a time when a higher temperature has been attained in the tube.Because the atomic-emission signal is sharply temperature dependent, an increase in the sensitivity of the emission method can be predicted with the use of a platform. Experimental A long focus lens (f=130 mm) was used to focus light from the centre of the furnace on to the entrance slit, while preventing any direct tube wall emission entering the monochromator. A Spectra- metrics SMI I11 kchelle monochromator was used in the sequential mode of operation. The high resolution grating rejected much of the background emission from the tube, allowing better processing of the analyte signal. The wavelength modulation chopper was located at the exit slit and an external power supply was used to drive the chopper and provide a reference signal.Signals from the photo- multiplier were amplified by a pre-amplifier and processed by an Ortec Brookdeal precision lock-in amplifier. The output from the lock-in amplifier was displayed on a potentiometric recorder. The uncorrected signal could be measured directly from the pre-amplifier while the signal could also be monitored at this point with an oscilloscope. Their dimen- sions were approximately 11 x 8 mm, the thickness being the same as that of the tube wall, The furnace used was a Perkin-Elmer HGA-72, using the gas-stop mode. The platforms used for this study were made from standard HGA-72 tubes.January, 1981 RESEARCH AND DEVELOPMENT TOPICS 11 Only the edges of the platform were in contact with the tube. Platforms were covered with a coating of pyrolytic graphite in situ to ensure that atomisation occurred from a reproducible, uniform surface.The tube was heated to 2100 "C and a 50 ml min-l flow of methane was introduced into the argon gas flow. The platforms were large enough to receive a 50-pl sample introduced by manual injection by micropipette. Results and Discussion I t was found that there was a delay in the heating of the platform compared with the stand- ard tube, and this resulted in a delay in the appearance of the emission signal of typically 1-2 s. The appearance of the signal was found to occur at the same temperature in the standard tube as on the platform. However, the temperature in the tube at the time of the emission follow- ing platform atomisation was 200-300 "C higher than that following tube atomisation.This raised temperature resulted in an increase in the magnitude and sensitivity of the emission signals. The final maximum temperature reached by the platform was almost the same as that obtained by the standard tube and this ensured that the platform could be adequately cleaned after each injection. Because thermal contact of the platform with the tube was restricted, longer drying times a t normal drying temperatures were required. Alternatively, effective drying was achieved by using higher temperatures in the drying stage. A tube wall temperature of the order of 400 "C was required to dry the sample on the platform in a reasonable time. However, once the solvent had evaporated the temperature of the platform rose rapidly, and it was possible to lose volatile elements during the drying stage by use of too high a temperature.Some of the detection limits obtained by use of this system are given in Table I. TABLE I EFFECT OF PLATFORM ON SENSITIVITY ACHIEVED IN CFAES Detection limit/pg 1-1 r - - - 7 Improvement Element Standard tube Platform factor Cr 0.044 0.023 2 Mn 0.06 0.029 2 c u 0.1 0.034 3 Pb 370 3.4 100 In 2.1 0.023 100 The platform is most effective in the determination of the more volatile elements, such as lead or indium, where improvements in sensitivity of up to a factor of 100 can be obtained. Significant improvements are, however, obtained for almost all elements. Typical values of relative standard deviation for aqueous standards are 2-3% for manual injection. Detection limits for copper, chromium and manganese were sufficiently low to make feasible the determ- ination of these metals in clinical samples by means of CFAES.The technique has so far been applied to the determination of copper, manganese and chromium in urine and this work will be described more fully elsewhere. The levels of these elements in urine are between one and two orders higher than the aqueous detection limits that are attained for CFAES (shown in Table I). The use of wavelength modulation eliminated the background emission from the matrix, and the use of the platform increased the degree of dissociation and reduced the effects of sample spreading. An analysis of urine for all three elements using samples from normal subjects and from patients under intravenous feeding gave results that were in good agreement with other analytical techniques, such as CFAAS and atomic-fluorescence spectrometry.The precision achieved for the three elements was about 5%. The only sample pre-treatment required for CFAES analysis was 1 : 1 dilution of the urine with water. Conclusions Platform atomisation appears to be a valuable technique for improving the sensitivity of the carbon furnace atomic emission method, particularly for more volatile elements. The platforms are durable, inexpensive to prepare and straightforward to use, and a reduction in wear of the central portion of the tube improves tube lifetimes; sample spreading effects are also reduced.Anal. Proc. It appears that the CFAES procedures adopted for the analysis of the three trace elements in urine provide accurate results of sufficiently high precision for routine use.The high sensitiv- ity of the method has allowed procedures to be developed that involve minimum sample treat- ment and which therefore reduce substantially the possibilities for contamination. Further work ainied at extending this instrumental method to other elements and sample types is in active progress in our laboratory. 12 RESEARCH AND DEVELOPMENT TOPICS 2. 3. 4. 5 . 6. 7. 8. References Ottaway, J . M., Hutton, R. C., Littlejohn, D., and Shaw F., Wiss. 2. Karl-Maw-Univ., Leipzig, 1979, Littlejohn, D., and Ottaway, J . M., Analyst, 1977, 102, 553. Michel, R. G., Sneddon, J., Ottaway, J . M., and Fell, G. S., Analyst, 1981, in the press.Ottaway, J. M., and Shaw, F., Appl. Spectrosc., 1977, 31, 12. L’vov, B. V., Pelieva, L. A., and Sharnopolskii, A. I., Z h . Prikl. Spectrosk., 1977, 27, 395. Gregoire, D. C., and Chakrabarti, C. L., Anal. Chem., 1977, 49, 2018. Slavin, W., and Manning, D. C., Anal. Chern., 1979, 51, 261. Katskov, D. A., and Grinstein, I. L., Zh. Prikl. Spectrosk., 1978, 28, 968. 28, 357.January, 1981 RESEARCH AND DEVELOPMENT TOPICS 13 Simplex Optimisation Results With the exception of optimum conditions, which lay outside the physical restraints of the instrumentation, the univariant search optima agreed well with the results obtained by the Simplex optimisation procedure. The results for the optimisation of a number of different elementsin both nitrogen-cooled and all-argon plasmas are summarised in Table I.There are interesting comparisons to be made between these two different types of plasma. The optimum conditions for the three elements in the nitrogen-cooled plasma show considerable variations, whereas those in the argon-cooled plasma show little variation. This is particularly notable as regards power and viewing height. If compromise conditions are to be used in the plasma for the simultaneous multi-element analysis of metals it would appear that these could more easily be achieved using an argon- cooled plasma. The optimum powers obtained also show an interesting trend (the power coupled into the plasma being measured by means of a calorimetric m e t h ~ d ~ ? ~ ) . In the all-argon plasma, al- though the four lines chosen covered a large range of excitation energies (the term difficulty of excitation in Table I is an empirical term representing the sum of excitation energy plus ionisation energy) the optimum powers covered a relatively small range (0.13 kW).Con- versely, in the nitrogen-cooled plasma the optimum power appeared to increase with increasing difficulty of excitation covering the range greater than 0.94 kW; indeed, the power curve was still rising sharply for the Mn ion line at the physical limit of the instrumentation and hence a true optimum could not be obtained. These contrasting trends seem to suggest a fundamental difference between the two excitation processes occurring in these two plasmas. TABLE I COMPARISON OF OPTIMISED CONDITIONS FOR DIFFERENT ELEMENTS Difficulty Signal to of Gas flow-ratell min-l background Wavelength/ excitation/ Coolant r----A--- -, Height/ Power/ ratio a t Element nm eV gas Coolant Plasma Injection inm kW 1 p.p.m.257.6 403.1 MnJ1' 249.8 228.8 B As I 257.6 Mn {;I 403.1 I 3 1 249.8 As I 228.8 12.2 Ar 3.08 Ar 4.9 Ar 6.7 Ar 3.08 N, 12.2 N2 4.9 N2 6.7 N, 4.6 14.0 8.7 14.0 5.4 9.4 5.4 12.3 4.6 9.9 7.0 3.1 4.6 8.9 4.0 10.0 0.38 0.58 0.36 0.40 0.40 0.49 0.45 0.38 20 26 21 20 18 26 14 14 0.59 0.50 0.46 0.46 1.20* 0.26 0.82 1.16 1.5 12.0 1.2 2.0 x 10-2 1.2 17.0 0.45 0.95 x * True optimum not obtained. The optimisation experiments summarised in Table I were performed with the analyte dis- solved in distilled - de-ionised water. With arsenic, however, a further optimisation was carried out in an all-argon plasma with the arsenic analyte dissolved in a solution containing 10 g 1-1 of chromium in order to optimise the determination of traces of arsenic in chrome metal.The results showed a deterioration in the optimum signal to background compared with the arsenic solution in distilled water and a shift in optimum conditions, particularly in the power, which changed from 0.46 to 0.9 kW, thus showing that the nature of the analysis to be carried out is an important factor to be considered when choosing the operating conditions. Evaluation of the Modified Torch Having developed a method for optimising the plasma it was then possible to use this method to compare the performance of the modified torch with the standard Greenfield design directly. Simplex optimisation of the two torches was carried out for the Mn 257.6 nm ion line.For the modified design both argon and nitrogen coolants were used; for the Greenfield torch, however, only nitrogen coolant was used as softening in the torch occurred when argon coolant was used. The optimum operating condi- tions for the two torches show some differences, particularly in the plasma gas flow rate, which The results of this comparison are summarised in Table 11.14 RESEARCH AND DEVELOPMENT TOPICS Anal. Proc. is much higher for the new torch. More important, perhaps, is the significant increase in signal to background ratio for the new torch (approximately three times), showing that a considerable advantage in sensitivity is gained for this particular element. TABLE I1 COMPARISON OF OPTIMISED OPERATING CONDITIONS FOR DIFFERENT TOKCH DESIGNS Gas flow-rate/l min-l Signal to Coolant -7 Height/ Power/ background Torch gas Coolant Plasma Injector mm kW ratio Greenfield design .. N, 4.0 2.5 0.6 19 1.3 0.4 New design . . . . Ar 4.6 14.0 0.38 20 0.59 1.5 New design . . . . N, 4.6 9.9 0.4 18 1.2 1.2 Sodium Interference Studies Some interesting interference effects were observed when large concentrations of sodium were present in the plasma, for example, after sodium carbonate - peroxide fusions of siliceous alloys. When the sodium ion concentration was increased large interferences were observed for the manganese 403.1 nm atom line under optimum conditions (e.g., 380:/, at 10000 p.p.m. of sodium). Further work showed the injector flow-rate to be a critical factor in the inter- ference mechanism, and by reducing this gas flow the interference could be greatly reduced (e.g., to 20y0 at 10000 p.p.m.of sodium). These interferences could not be reproduced when the torch was replaced with an air - acetylene burner, indicating that these effects originate in the plasma and not in the nebuliser. The results for the analysis of alloys where the fusion dissolution method was used showed good agreement with results obtained by using other methods of analysis (atomic-absorption spectrometry and spectrophotometry). Thus, these effects can clearly be overcome in practical analysis by the buffering of standards to match samples and the judicious choice of operating conditions. Conclusions The Simplex optimisation technique has been shown to be a fast and effective method of optimising the plasma.The results obtained not only identify the optimum conditions for a given analytical situation but can also give insight into the processes that occur in different types of plasma. Interferences have been shown to occur in the ICP but with proper under- standing of the conditions under which they occur their effect can be minimised. The analyti- cal results obtained for a number of highly refractory metallurgical alloys using the ICP show ICP optical emission spectroscopy to be well suited to this type of analysis. The authors thank the Science Research Council and the London and Scandinavian Metal- lurgical Co. for help in purchasing the equipment and the Science Research Council and the United Nations for financial support (for M.R.C.and D.M.K., respectively). References 1. 2. 3. 4. 6. 6. Greenfield, S., Jones, I. LI., and Berry C. T., Analyst, 1964, 89, 713. Ebdon, L., Mowthorpe, D. J., and Cave, M. R., Anal. Chim. Acta, 1980, 115, 171. Greenfield S., Jones, I . LI., McGeachin, H. McD., and Smith, P. B., Anal. Chim. Actn, 1975, 74, 225. Nelder, J. A., and Mead, R., Comput. J . , 1965, 7, 308. Ebdon, L., Cave, M. R., and Mowthorpe, D. J.. Anal. Chim. Acta, 1980, 115, 179. Greenfield, S., and McGeachin, H. McD., Anal. Chim. Acta, 1978, 100, 101.January, 1981 RESEARCH AND DEVELOPMENT TOPICS 15 region, whilst a 400-W tungsten halogen source is employed in a similar instrument designed to operate in the near-infrared region. These instruments have been described in detail el~ewhere.~,~ Spectra obtained from these instruments are normalised using a digital scan recorder which outputs the quotient obtained by dividing the sample spectrum by a previ- ously stored spectrum of carbon black measured over the same wavelength range.Quantitative Examination of Thin-layer Chromatography Plates Existing methods for the quantitation of samples on thin-layer chromatography (TLC) plates involve either measurements in situ or the removal of the sample from the plate prior to its analytical determination. The highly light-scattering nature of TLC adsorbent materials creates difficulties for in situ densitometric measurements, whilst the non- quantitative recovery of eluted fractions and the sample pre-treatment required before measurements can be made result in determinations carried out upon material removed from TLC plates being complicated and exacting.Aluminium foil-backed TLC plates were used for the preliminary studies as disks could be cut out from these directly with the sample spot at the centre and placed in the OAS cell.4 A 1-pl aliquot of each of a series of standard solutions of fluorescein in the concentration range 0.2-2.0 pg pl-1 was applied to the plate and, following development, disks (20 mm 0.d.) were cut out around the spots and placed in the OAS cell. Measurements were taken at the peak wavelength in the spectrum of fluorescein (447 nm) and at the background (600 nm). Plotting the difference in signal magnitudes measured at 447 and 600 nm against mass of fluorescein in the analyte spot produced a linear calibration graph over the mass range studied. The relative standard deviation of these measurements was calculated to be about 0.1%.A number of errors were introduced in the cutting out of disks from the TLC plate. The adsorbent layer was easily chopped around the edge of the disk and the aluminium foil was found to give a large background signal. The position of the sample spot on the cut disk had to be accurately reproducible as the incident radiation intensity was not distributed exactly evenly across the area of the sample. The sample was removed from the plate using a vacuum device based on the design by M~lhern,~ and collected on a sintered disk, which was placed directly into the OAS cell.A linear calibration graph was obtained for fluorescein on silica gel over the range 0.2-1.2 pg of fluorescein. The relative standard deviation of these results was about O.OSyO. The procedure developed for fluorescein on TLC plates was then extended to the determination of three dyes separated on a TLC plate. The dye mixtures employed contained carmoisine, tartrazine and brilliant blue FCF, which had been extracted from fruit gums by column chromatography. A series of standard solutions of the dyes were also separated on the same TLC plate. Linear calibration graphs were obtained and the concentrations of dyes in the fruit gums determined. The use of glass-backed TLC plates was then investigated. Studies in the Near-infrared Region The absorption bands observed in the near-infrared region may be attributed to overtones and combinations of the fundamental vibrational modes observed for a particular molecule.The bands observed most frequently in this spectral region are those relating to hydrogenic systems such as -CH, -OH and -NH. Of particular interest is the combination band characteristic of the hydroxyl group in water observed at about 1.9 pm. Measurement of the 1.9-pm band in the near-infrared region offers the potential for determining water in solid samples and distinguishing the presence of water from bound hydroxyl groups. This approach has been applied to the determination of moisture in samples of single-cell proteh6 Samples of single-cell protein were dried to constant mass at 105 "C and then placed in a series of atmospheres of controlled humidity.A set of standards was prepared to cover the moisture range 0-ll.6y0 m/m. Optoacoustic signal magnitudes were measured for each sample at 1.9 and 1.55 pm. The measurement of the -NH band at 1.55 pm was taken as an internal standard. The ratio of the optoacoustic signals measured at 1.9 pm was plotted against the percentage moisture content of the sample and yielded a linear calibration graph with a relative standard deviation of about 0.0470 on each point.16 RESEARCH AND DEVELOPMENT TOPICS Anal. Proc. Using wide-line NMR a linear calibration graph was achieved only at moisture contents greater than about 6%. A calibration graph almost parallel to the abscissa was obtained for moisture contents less than about 6%.The small variation in the NMR signal per unit mass of sample with moisture content at moisture contents less than about 6% has been attributed to the water being relatively strongly bound to the protein. The disadvantages of employing wide-line NMR for the determination of moisture include the lack of specificity of the tech- nique to protons in water and the requirement to weigh the sample before measurements are made. It has been demonstrated that the mass of sample does not affect the determination employing OAS provided that the base of the cell is covered with sample. It has been possible to perform quantitative analyses of other samples employing OAS in the near-infrared region. A wide variety of copolymers of vinyl acetate and vinyl chloride are produced commercially.In the near-infrared region a band at about 2.15 pm may be assigned to an ester carbonyl group present in vinyl acetate.’ A series of powdered standard samples were employed containing vinyl acetate in the range 0-15y0. These samples were sieved to give two broad ranges of particle diameter, namely 8-9 and 20-250 pm. Measure- ments were made at 2.15 and 1.75 pm for each sample of copolymer. The measurement of the -CH, band at 1.75 pm was used for internal standardisation. The ratio of the opto- acoustic signals measured at 2.15 and 1.75 pm was plotted against percentage of vinyl acetate in the sample and linear calibration graphs resulted for both ranges of particle size. The relative standard deviation achieved in the measurements made was about 0.05%.The results obtained using OAS were compared with the results of a method employing diffuse reflectance spectroscopy. Linear calibration graphs were obtained when the samples of copolymer were sieved but the precision was found to be less than for the technique employing OAS. A comparative study was made using a technique employing wide-line NMR. Conclusions These investigations have indicated that OAS may be employed as a quantitative analytical technique for a number of sample types with absorptions in the UV - visible and near- infrared regions of the spectrum. For the samples studied, techniques using OAS have been shown to compete favourably with methods employing the more conventional techniques of wide-line NMR and diffuse reflectance spectroscopy.The enhancement of the optoacoustic signal observed for finely particulate materials has been utilised in the determination of substances adsorbed on TLC substrates. The lack of interference due to the effects of scattered radiation and the high sensitivity of the technique for this type of sample make OAS a useful addition to existing techniques for the qualitative and quantitative determination of analyte spots on TLC plates. References 1. 2. 3. 4. 5. 6. 7. Rosencwaig, A., and Gersho, A , , J . Appl. Phys., 1976, 47, 64. Adams, M. J., Beadle, B. C., and Kirkbright, G. F., AnaZyst, 1977, 102, 569. Adams, M. J . , Beadle, B. C., and Kirkbright, G. F., Anal. Chem., 1978, 50, 1371. Castleden, S. L., Elliott, C. M., Kirkbright, G. F., and Spillane, D. E. M., Anal. Chem., 1979, 51, Mulhern, B.M., J . Chromatogr., 1968, 34, 558. Castleden, S. L., Kirkbright, G. F., and Menon, K. R., Analyst, 1980, 105, 1076. Haslam, J., Willis, H. A,, and Squirrell, D. C. M., “Ideiitification and Analysis of Plastics,” Second 2152. Edition, Butterworths, London, 1972January, 1981 RESEARCH AND DEVELOPMENT TOPICS 17 Beeghly,l the mobile nitrogen, consisting of atomic nitrogen present in the steel lattice and that released by the dissolution of iron and manganese nitrides, is evolved as nitrogen gas. Typically a steel will contain 1-50 p g g l of mobile nitrogen. This means that at room temperature and atmospheric pressure the volume of nitrogen evolved from a 1-g sample is no more than 0.04 cm3. The nitrogen has to be determined quantitatively after being swept out of the solution by a carrier gas.Titanium sponge heated to 950 "C will absorb nitrogen from an inert gas such as argon.2 The amount of nitrogen absorbed can then be determined by a Kjeldahl method3 with an indophenol blue colorimetric f i n i ~ h . ~ However, the amount of Specpure titanium required in order to achieve complete removal of nitrogen from argon was 10 g and the method was too expensive and time consuming for routine operation. An iron catalyst will promote the reaction between nitrogen and hydrogen to give ammonia. This has been used by T01g5 for the microdetermination of nitrogen in organic compounds. In this study a commercial catalyst (BASF S6-10) based on iron oxide promoted with oxides of aluminium, calcium, magnesium and potassium was used.The ammonia produced was absorbed in a triethanolamine - hydrochloric acid buffer solution at pH 6.9 and determined potentiometrically using an ammonium ion-selective electrode by the method of Headridge and Long.6 Being exothermic, the reaction between nitrogen and hydrogen is favoured by low tempera- ture. The catalyst used in this instance has a working range of 400-550 "C. The reaction was carried out at atmospheric pressure. Fig. 1 shows a plot of percentage conversion of 50-pg nitrogen samples introduced into hydrogen streams against temperature for a 2-h collection period. The optimum temperature for the reaction is 450460 "C, although even in this temperature range there is only 50-60~0 conversion. In order for this method to be applicable to the problem in hand the degree of conversion should preferably be not less than 9576.This has been attempted in three ways. No catalyst that works efficiently at room temperature is known. 70 I I Temperatu re/"C Fig. 1. Graph of percentage conversion of nitrogen to ammonia against temperature for a 2-h collection period. Both of these methods involve the continuous removal from a carrier gas of nitrogen as it is produced by the dissolution of a steel sample. Hence they have to facilitate the complete removal of nitrogen from the carrier gas over a period of 20-30 min when the nitrogen has a continuously varying, though very small, concentration. The carrier gas itself must also be as free from nitrogen as possible because any nitrogen present will contribute to the blank.A method that involves the collection of the total amount of nitrogen evolved from the steel and its subsequent determination by a comparison technique is a possible alternative. Such a technique is gaseous refractometry. When a coherent beam of light is split and then passed through two media with different refractive indices, an interference pattern results on recombination of the beams, because the speed of light is different in each medium. As the composition of one of the media is changed the pattern appears to move relative to a fixed position. The degree to which it moves is dependent on the change in composition of the medium. Fig. 2 illustrates a Rayleigh interferometer with which refractive indices can be measured after production of an interference pattern.18 \ I RESEARCH AND DEVELOPMENT TOPICS A B Anal.Proc. Refractometers are commonly used as detectors in high-performance liquid chromato- graphy as the range of refractive indices of liquids is very wide. However, the refractive indices of gases are all very similar and close to unity. For the application of this technique to the determination of mobile nitrogen in steel the carrier gas, in addition to being stable in the organic solvent - halogen mixture, should have a refractive index significantly different from that of nitrogen. For this reason, sulphur hexafluoride was chosen, with a refractive index of 1.000895 at S.T.P. for a wavelength of 589 nm, compared with 1.000296 for nitrogen and 1.000281 for argon. For the determination the reference cell was continuously pumped to a vacuum while the sample cell was filled with different pressures of sulphur hexafluoride.This cell was then slowly evacuated and the number of fringes that moved over a fixed position was noted from the potentiometric recorder. The relationship between the number of fringes moved and the pressure of sulphur hexafluoride was found to be linear. Typically, a movement of one fringe corresponded to a pressure fall of 0.7 torr. The sample cell was then filled with mixtures of sulphur hexafluoride and nitrogen of varying composition. The difference in number of fringes moved compared with the same pressure of pure sulphur hexafluoride was measured. Fig. 3 shows a graph of number of fringes moved against the molar fraction of nitrogen in the gas mixture.The limit of detection of the method, defined as twice the standard deviation of a series of determinations a t or near the blank level, was 0.00015 molar fraction of nitrogen in sulphur hexafluoride. As 1.5 1 of sulphur hexafluoride at about 600 torr are required to flush the nitrogen out of a solution of 1 g of steel in the organic solvent - halogen mixture, this corresponds to a detection limit of approximately 220 pg g1 for mobile nitrogen in steel. 1 1 1 1 1 1 1 1 1 , I 0.0002 0.0006 0.001 0 0,001 4 0.001 8 0.0022 Molar fraction of nitrogen in sulphur hexafluoride Fig. 3. Graph of number of fringes moved against molar fraction of nitrogen in sulphur hexafluoride.January, 1981 RESEARCH AND DEVELOPMENT TOPICS 19 The use of a 2-mW helium - neon laser as the light source in preference to a tungsten filament lamp and photoelectric detection in place of visual detection of fringe movement has improved the sensitivity of the method by approximately two orders of magnitude from that specified by the manufacturer. Further improvements would be expected if an electrical system of pressure measurement could be incorporated and the instrument could be isolated from extraneous vibrations, thus allowing easier and more accurate pressure measurements and enabling small fractions of fringes to be measured with confidence. None of these three methods has yet proved good enough to be applicable to the deter- mination of mobile nitrogen in steels.Currently, work is being done to improve the catalytic system, and the suggested improvements are being made to the refractometry apparatus.It is hoped that further work, based on the results of this initial investigation, will lead to the early solution of the problem of determining extremely small amounts of nitrogen released from steels by dissolution in organic solvent - halogen mixtures. The authors express their gratitude to Dr. D. A. Dunmur for providing advice and equip- ment for the study of gaseous refractometry and to the Science Research Council for a Studentship to A.A.B. References 1. 2. 3. 4. 5. 6. Beeghly, H. F., Anal. Chem., 1952, 24, 1713. Dombrowski, H. S., Anal. Chem., 1954, 26, 526. Thompson, J . M., Anal. Chem., 1953, 25, 1231. Bach, B. B., Willis, R. R., and Reid, R. B., Metallurgia, 1966, 74, 191 Tolg, G., 2.Anal. Chem., 1964, 205, 40. Headridge, J. B., and Long, G. D., Analyst, 1976, 101, 103.20 RESEARCH AND DEVELOPMENT TOPICS Anal. Proc. Despite the good precision obtained using micropipettes, several drawbacks exist to this method of sample application. The application of large numbers and/or large volumes of samples to the plate is very time consuming, especially if the size of the starting spot is to be kept to a minimum. Viscous solutions are not amenable to capillary transfer and contact between the micropipette and the adsorbent layer often results in damage to the layer and blockage of the micropipette. A novel approach to sample application in TLC has recently been described by Fenimore and Meyer.l Measured volumes of sample solution are evaporated in depressions formed in a non-wetting polymer film and after removal of the solvent the residues are transferred from the film to the TLC plate by direct transfer.Results obtained by using this technique look promising. This method of sample application should be particularly suitable for samples of biological origin, where large volumes of sample must be used to achieve adequate sensitivity or the samples are too viscous for application by micropipette. Plate Technology The quality of adsorbents used in TLC has improved in recent years following successful developments in column packing materials for liquid chromatography. High-performance thin-layer chromatography (HPTLC) plates with both silica gel and cellulose adsorbents are now available from several manufacturers.The silica gel HPTLC plates employ particles of the same pore size as those used in conventional TLC (6 nm), but with a smaller mean particle size (5 pm) than on conventional plates (20 pm). The particle size distribution of the silica gel (3-8 pm) is also much narrower than that with conventional TLC plates (5- 40 pm) and the layer thickness is slightly reduced, being 0.20 mm as opposed to 0.25 mm. I t has been ~ l a i m e d ~ - ~ that HPTLC leads to improved resolution, greater sensitivity, a higher degree of precision and shorter analysis times than TLC. In most instances, however, these improvements can also be obtained with TLC plates if appropriate experimental technique is employed. Very small starting spots (maximum diameter 1.0 mm) and short development distances (30-40 mm) are prerequisites for HPTLC.Table I gives separation numbers and development times for the separation of a threc- component mixture by linear and radial development on TLC or HPTLC plates. The results show that HPTLC offers no advantages over TLC for the separation of complex mixtures, as the separation number for HPTLC exceeds that for TLC only when short development distances are employed, and the number of components that can be separated in such distances is limited. The reason for the lower separation numbers obtained when HPTLC plates are developed for distances greater than 3040 mm can be seen from the relative development times. HPTLC plates develop more slowly than TLC plates because the narrower capillary channels in the adsorbent layer restrict the flow of mobile phase through the plate.Thus, for a given development distance the HPTLC plate takes longer to develop and more diffusion of the separated components occurs, with a consequent decrease in the separation number. TABLE I SEPARATION NUMBERS AND DEVELOPMENT TIMES FOR TLC AND HPTLC Development Type of plate technique TLC . . . . Linear TLC . . . . Linear TLC . . . . Linear HPTLC . . Linear TLC . . . . Radial HPTLC . . Radial Development distance/mm 150 80 50 50 23 23 Separation number* 10.4 8.8 7.5 6.6 4.4 6.4 Development time/min 30 11 5 8 6.5 6.5 * Separation numbers for the separation of 4-($-nitrobenzyl)pyridine, 3-nitro- aniline and 2,4-dichloroacetophenone with hexane - acetone (80 + 20) as the mobile phase The increased sensitivity that is frequently claimed for HPTLC results mainly from the Development times are use of shorter development distances than those employed in TLC.January, 1981 RESEARCH AND DEVELOPMENT TOPICS 21 thus reduced and the separated components are less diffuse.With the test mixture previously described a three-fold increase in sensitivity was obtained when the development distance was reduced from 150 to 50mm and a further two-fold increase was achieved with radial development for about 25mm. Hence it may be possible to obtain almost an order of magnitude increase in sensitivity using HPTLC but only when the separation can be accom- plished in a very short development distance. The major advantages of HPTLC over TLC are increased precision of analysis and the ability to obtain highly reproducible R F data.These result from closer control of the experi- mental conditions and the more homogeneous adsorbent coatings found on HPTLC plates. The adsorbent layers are particularly suitable for in situ densitometry, and Janchen and Schmutz5 reported a reproducibility of photometric measurement of less than 0.4% relative standard deviation for the determination of benzodiazepines at the nanogram level. In addition to normal-phase HPTLC plates, reversed-phase HPTLC plates have also become available. These plates are coated with microparticulate silica having an ethyl, octyl or octadecyl moiety bonded to the surface and are particularly useful for the separation of polar componds such as carbamate and triazine pesticides and their metabolites.Reversed- phase separations depend on partition of the solute between the bonded and mobile phases as opposed to the adsorption mechanisms that operate in normal-phase systems. Selectivity is thus achieved by choice of the reversed-phase coating and the polarity of the solvent system employed. Methanol - water and acetonitrile - water are usually employed as solvent systems in reversed- phase HPTLC. Increasing the water content (i.e., the polarity) of the mobile phase favours retention of the solute on the plate. Unfortunately, the plate coatings are extremely hydro- phobic and although we have used solvents containing a high proportion of water, develop- ment is very slow with solvents containing more than 20y0 of water.This effect was partially overcome, however, by the addition of acid to the mobile phase and it was possible to separate cyanazine (a triazine herbicide) and five hydrolysis products using methanol - water - formic acid (50 + 50 + 0.5) as the mobile phase. Reversed-phase HPTLC plates have also been used in this laboratory to determine octanol - water partition coefficients for candidate herbicides and insecticides. This tech- nique has proved most useful for compounds with very low water solubilities where con- ventional partition coefficient measurements are prone to considerable error. Development Techniques The improvements in plate coatings previously described have led to a re-examination of development techniques in TLC. There are several drawbacks to the use of the large- volume developing tanks that are frequently employed in conventional TLC.There is no control over the gas-phase composition or the rate at which the mobile phase is fed to the adsorbent layer. Mixed solvents also lead to preferential adsorption on the plate and the composition of the mobile phase is thus continuously changing during development. In contrast, the stationary, mobile and gas phases can all be closely controlled when radial development equipment (Camag U-Chamber) is used and this method of development is therefore preferred for HPTLC separations. In the Camag U-Chamber the mobile phase is pumped from a motor-driven syringe, through a platinum - iridium capillary, to the centre of the plate. As with linear TLC, the rate of migration of the solvent front decreases with the square of the development distance.In radial chromatography, however, the plate area increases with the square of the development distance and so the mobile phase can be supplied to the plate a t a constant flow-rate. With the Camag equipment this rate is adjustable between 0.1 and 1.0 p1 s-l. The mobile phase is applied at the limit of the absorbing capability of the layer, which eliminates variations due to capillary action and gives repro- ducible results and greater resolution. Because the development chamber volume is relatively small on the Camag apparatus (about 6 ml), equilibrium between all three phases is rapidly established during development. The activity of the adsorbent layer can be modified prior to development by passing solvent and/or sulphuric acid - water vapour through the develop- ment chamber.The ability to control all three phases makes radial chromatography a highly reproducible technique. Relative standard deviations of 1% for the reproducibility of RF values and 1.5%22 RESEARCH AND DEVELOPMENT TOPICS Anal. Proc. for the precision of analysis have been obtained using this method of plate development. In linear HPTLC it is more difficult to obtain such precise data because of variations in the thickness of the adsorbent layer at the edges of the plate. Radial development gives increased separation power for compounds with low RF values, as described by the equation RF linear = (RF radial)2. This feature is illustrated in Figs. 1 and 2, which show the separation of a three-component mixture by linear and radial chromatography, both plates having been developed for the same distance.Because of the increased separation power, total resolution of the components can usually be achieved in a shorter development distance by radial chromatography. Diffusion of the separated com- ponents is thus minimised and the sensitivity of radial HPTLC is superior to that of linear HPTLC. I I I I C 0 3 .- .- L 0 I 0 10 20 30 DeveloDment distance/mm A Fig. 1. Chromatogram of three-component mixture separated by linear HPTLC. Peaks: A = 4-(p-nitrobenzyl)- pyridine; B = 3-nitroaniline; and C = 2,4-dichloroaceto- phenone . 0 10 20 30 Development distance/mm Fig. 2 . Chromatogram of three-component mixture separated by radial HPTLC.Peaks as in Fig. 1. Translation of data from TLC to high-performance liquid chromatography (HPLC) has been reported previou~ly,~?~ but these experiments were carried out by linear development in saturated tanks. Samples to be chromatographed on the Camag U-Chamber may be injected directly into the mobile phase in a manner analogous to sample introduction in HPLC, and thus retention data obtained by radial development should be more suitable for transfer to HPLC than the data obtained by linear development. The potential of data transfer from linear and radial HPTLC to HPLC has been examined using normal- and reversed-phase test systems. Good correlations were obtained and it was possible to predict retention times accurately in HPLC from linear and radial HPTLC data.In view of the limited separation efficiency of TLC in comparison with other chromato- graphic techniques, such as gas chromatography and HPLC, approaches for improving the separation efficiency of TLC have been examined. Programmed multiple development (PMD) is such an approach, in which the TLC plate is automatically cycled through a pre- set number of developments. In each succeeding development the solvent moves further up the plate, and following each development the solvent front is caused to recede to the sample origin by controlled evaporation. During PMD the plate remains in contact with the solvent reservoir and the solvent flows towards the solvent front whether the front is advancing or receding. Thus, re-concentration of the separated components takes place during PMD and the problem of spot diffusion, normally associated with long development times, is minimised.January, 1981 RESEARCH AND DEVELOPMENT TOPICS 23 Commercial equipment for PMD is available (Regis PMD Chamber) that uses radiant heat from an infrared lamp to remove the solvent from the TLC plate.It would appear,a however, that heating activates the adsorbent and results in streaking of the components along the plate. Thus, initial experiments on PMD in this laboratory have been carried out in a modified sandwich chamber using an inert gas flow to remove the solvent from the plate. It was necessary to wash the plates with solvent before use to prevent the occurrence, on development, of bands from impurities in the plate coating.Separation of a mixture of 3-chloro-4fluoroaniline and nitralin was examined using both linear and multiple develop- ment. The latter technique gave complete resolution of both components and also of impuri- ties in the nitralin, whereas linear development failed to resolve the two major components. Other solute - solvent systems are currently being examined by multiple development pro- cedures. Because re-concentration of the separated components occurs twice during each develop- ment cycle, the intial spot diameter is not particularly critical in PMD. Hence much higher sample loadings can be used than those normally employed in TLC. This is of advantage in the determination of trace components (less than 0.1% m/m) in the presence of major components.The increased separating power of PMD over conventional TLC may also be useful for the separation of closely related compounds, such as the isomers of biologically active materials. Quantification of the Separated Components Although direct photometric measurement is the most widely used technique for quanti- fication of components separated by TLC, many compounds are not amenable to such examination. Consequently, we have recently examined the Iatroscan TH-10 analyser, an instrument that combines the technique of TLC with flame-ionisation detection. TLC separations are carried out on silica rods and the separated components are detected and quantified by passing the rods through a flame-ionisation detector. The silica rods, with dimensions of about 150 x 0.9 mm o.d., have a sintered coating of silica 75 pm in thickness.Sample solutions are applied near the end of the rods, which are subsequently developed in a conventional TLC tank. After development, the mobile phase is removed by evaporation and the rods are placed in the TH-10 analyser and scanned through an air - hydrogen flame. The flame vaporises and ionises the solutes and a collector electrode monitors the ion current, which is amplified and displayed on a pen recorder. Two types of rod have been examined, type S, coated with conventional TLC silicas, and type S 11, coated with HPTLC silicas. The S I1 rods exhibited the same separation efficiency as the S rods but gave improved sensitivity (about 50y0), presumably owing to increased efficiency of vaporisation from the more uniform silica surface.The sensitivity of the Iatroscan TH-10 analyser is dependent both on the carbon number of the compound being examined and, to a certain extent, on the rate of vaporisation of that compound from the silica rod. For the compounds studied, however, which included wild oat herbicides, organo- tin compounds and non-ionic surfactants, a detection limit of 200 ng (signal to noise ratio = 5 : 1) was typical. Responses were obtained for samples in the range 200 ng-40 pg, although 1-20 pg was generally found to be the optimum linear working range. The major problem with the Iatroscan system was the poor reproducibility of the technique, with a relative standard deviation of about 10%. This irreproducibility was found to be largely due to variation in “sensitivity” down the length of each rod. Microscopic examination has shown that these “sensitivity” changes can be attributed to variations in the layer thickness.Thus it has been found necessary to select rods of similar characteristics from several batches in order to minimise the rod-to-rod variation. Despite the poor reproducibility of the Iatroscan TH-10 analyser, this system has proved useful for the semi-quantitative determination of compounds not amenable to other methods of quantification (e.g., lipids, steroids, vitamins, sugars, organometallics and surfactants). References 1. Fenimore, D. C., and Meyer, C. J., in Zlatkis, A., Editor, “Advances in Chromatography 1979: Pro- ceedings of the Fourteenth International Symposium held in Lausanne, September 24-28, 1979,” University of Houston, Houston, Texas, 1979, p.583.2. 3. 4. 5. 6. 7. 8. RESEARCH AND DEVELOPMENT TOPICS Anal. PYGC. Halpaap, H., and Kipphahn, J., Chromatographia, 1977, 10, 613. Halpaap, H., and Ripphahn, J., Chromatographia, 1977, 10, 643. Kaiser, R. E., J . High Resol. Chromatogr. Chromatogr. Commun., 1978, 1, 164. Janchen, D., and Schmutz, H. R., J . High Resol. Chromatogr. Chromatogr. Commzcn., 1979, 2, 133. Schlitt, H., and Geiss, F., J . Chromatogr., 1972, 67, 261. Soczewinski, E., and Golkiewicz, W., J . Chromatogr., 1976, 118, 91. Saliman, P., Shell Development Co., personal communication, 1979.January, 1981 RESEARCH AND DEVELOPMENT TOPICS 25 response veysus time curve will be proportional to the total amount of electricity, Q, resulting from detection of an electroactive species, where Q is given by .... * * (3) Q = k'nFSv,"Cb(t)dt . . .. = k'xnFv,"-l x being the number of moles of species undergoing electrode reaction. If the area under the response peak is plotted against vf on a log - log scale, the slope of the resulting straight line is cc- 1. When the electrode has tubular geometry with the electrolyte filling the tube, the Levich model predicts a value of 0.33 for cc. This has been confirmed for two experimental arrange- ments each having tubular platinum electrodes.2J2 Values for other electrode configurations are not available in the literature except for a value of 0.5 quoted for a flat glassy carbon electrode with eluate containing metol drifting across its ~ u r f a c e .~ The data contained in Fig. 1 lead to values of 0.09 and -0.99 for the DME and platinum cells, respectively, suggesting a very much greater dependence of il on flow-rate with the latter. Other values of cc have been derived for a few electroactive substances under a variety of conditions (applied potential, eluting medium and electroactive substance being varied) but they are very variable and general experimental deductions are not possible a t present regarding optimum electrode geometry and operating conditions. The electrode response, as measured by peak height, increased with increasing drop-time, reaching a plateau at sufficiently long drop-times. For example, for nitrobenzene in a 1 : 1 V/V mixture of Britton-Robinson buffer - methanol at pH 4.5, with a flow-rate of 2 ml min-l and the electrode held a t -1.7 V with respect to a silver - silver chloride electrode in 0.1 M potassium chloride solution, the response plateau was reached at a drop-time of about 0.7 s.As drop- time increases, the drop size also increases, with a consequent increase in charging current at the electrode; thus the background current (noise) in the detector circuit may require damping out. Roth detectors gave reasonably good and similar reproducibility; for ten repetitive injections of electroactive species, the coefficient of variation of each was 4%. However, the platinum electrode is subject to surface poisoning and requires frequent chemical cleaning, which would make it unsatisfactory for repetitive HPLC. This problem is overcome in the successful detector assembly of Fleet and Little,' in which the electrode is glassy carbon, by directing the eluate from a jet on to the electrode surface. Rapid convective diffusional mass transfer The DME cell was designed so that the mercury drop-time could be varied widely.12 10 N 8 ?!6 E \ Y s 4 a 2 0 1 2 3 4 Flow rate/ml min-' Fig. 1. Dependence of peak area on flow-rate with 0.1 M KC1 as carrier a t an applied potential of -0.6 V relative to Ag - .4gC1 in 0.1 M KCI. A, DME detector with 10 p1 of 0.1 M Cu2+; and 13, platinum electrode detector with 20 pl of 0.1 M CU2+. u 15 10 5 0 (C 1 cu2+ - 15 10 5 0 15 10 5 0 Time/min Fig. 2. Chromatograms of Cu2+, Zn2+ and Cd2+ detected at different applied potentials of dropping- mercury electrode: A, -0.5 V; B, - 1.0 V ; and C, - 1.5 V relative to h g - AgCl in 0.1 M KC1.Column : 5mmi.d. x 1Ocm packed with Ionex-SA 15 (diameter 15-17 pm) cation exchanger eluted with a mixture 0.1 M in sodium tartrate, 0 . 0 4 ~ in tartaric acid and 0.04 M sodium chloride in water a t pH 4.0. Flow-rate, 6 ml min-I. Each injection (50 p1) contained 16.86 pg of Cd2+, 9.81 pg of Zn2+ and 9.53 pg of cu2+.26 FLOW INJECTION TECHNIQUES Anal. Proc. occurs at the point of impact, giving good detector sensitivity. The impact of the liquid on the electrode surface keeps the latter clean. For example, nitrobenzene and p-nitrophenol, separated on a column (5 mm i d . x 10 cm) of Partisil-10 ODS by elution with the Britton-Robinson buffer methanol (1 : 1 V / V ) mixture, each had detection limits of about 40 ng a t the DME detector. The corresponding detection limit for each of these sub- stances emerging from the same column into the Pye Unicam LC3 ultraviolet detector set at 254 nm was around 13 ng. The DME detector had a linear response range of at least 1000 for each of these substances. Selectivity of detection is possible with electrochemical detectors. It will depend on the relative decomposition potentials of the electroactive species involved. Examples are pro- vided in Fig. 2, from which it is seen that by successive reductions in the potential at the DME The sensitivity and linear range of response can be good. the responses first to zinc and then to cadmium disappear. The detection limit for copper was 300 ng. Conclusions Electrochemical detectors are potentially of use in HPLC involving neutral and ionic electro- active substances. The detector should preferably have a small dead-volume (less than approximately 8 p1) and operate with an indicator electrode that is not affected by the products of the chemical transformations occurring at its surface. The renewable surface of the DME and the wall-jet principle14 used by Fleet and Little’ are successful in meeting this specification. Insensitivity to changes in eluate flow-rate and to the composition of the eluting medium are desirable detector properties, as are electrode response time, selectivity, sensitivity and a good linear range of detection. Existing electrochemical devices go some way to meeting most of these attributes but further work can probably lead to considerable improvements in over-all performance and versatility. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. References Drake, B., Acta Chem. Scand., 1950, 4, 554. Johnson, D. C., and Larochelle, J., Talanta, 1973, 20, 959. Takata, Y., and Muto, G., Anal. Chem., 1973, 45, 1864. Girard, J . E., Anal. Chem., 1979, 51, 836. Dieker, J. W., van der Linden, W. E., and Poppe, H., Talanta, 1979, 26. 511. Lund, W., Hannisdal, M., and Greibrokk, T., J . Chromatogr., 1979, 173, 249. Fleet, B., and Little, C. J., J . Chromatogr. Sci., 1974, 12, 747. Koen, J . G., Huber, J. F. K., Poppe, H., and den Boef, G., J . Chromatogr. Sci., 1970, 8, 193. Joynes, P. L., and Maggs, R. J., J . Chromatogr. Sci., 1970, 8, 427. Michel, L., and Zatka, A., Anal. Chim. Acta, 1979, 105, 109. Hanekamp, H. B., Voogt, W. H., Bos, P., and Frei, R. W., Anal. Lett., 1979, 12, 175. Blaedel, W. J., and Yim, Z., Anal. Chem., 1978, 50, 1722. Levich, V. G., “Physicochemical Hydrodynamics,” Prentice Hall, Englewood Cliffs, N. J., 1962. Yamada, J., and Matsuda, H., J . Electroanal. Claem., 1973, 44, 189.

ISSN:0144-557X    

DOI:10.1039/AP9811800007

出版商:RSC    

年代:1981

数据来源: RSC

摘要:

26 FLOW INJECTION TECHNIQUES Anal. Proc. Flow Injection Techniques The following is a summary of one of the papers presented at a Meeting of the Midlands Region held on April 24th, 1979, at the University of Aston, Birmingham. Analytical Chemistry at the Interface D. Betteridge, E. L. Dagless, B. Fields and P. Sweet and D. R. Deans University College of Swansea, Singleton Park, Swansea, SA 2 8PP I C I Petrochemicals, Wilton, Cleveland, TS6 8 J E Flow injection analysis (FIA) is a form of continuous-flow analysis in which the sample is injected directly into the flowing carrier stream without air segmentati0n.l As a consequence, there is an increase in the speed of analysis and there is no longer any need first to add and then remove air bubbles. However, the most significant chemical fact about flow injectionJanuary, 1981 FLOW INJECTION TECHNIQUES 27 analysis (FIA) is not per se the absence of air segmentation or the mode of injection or the high sample throughput, although these mechanical factors are of the greatest analytical importance.It is the existence of two interfacial regions between the sample and carrier. Because of the conditions of flow-rate and tube diameter the mixing of sample and carrier can be viewed as a process of interaction, during which concentration gradients between the carrier and the core of the sample are established. The rate of mixing is rapid. It is also reproducible, predictable and easily varied. Thus, a t one extreme little mixing takes place and the FIA apparatus functions as a sample inlet system for some conventional determination.At the other extreme the sample and carrier are mixed more or less com- pletely and the reaction product is measured; this is what we may term a conventional FIA application. In our work we have been concerned exclusively with exploiting the chemical and physical changes that take place across the interfacial region. Insofar as we are dealing with fast reactions in flow systems, two practical problems arise in pursuing this investigation. The first is an instrumental one, resulting from the need to measure concentration profiles across the sample and to process the data obtained. This problem requires the development of sensitive flow detectors that are compatible with digital computers. The second problem is in sorting out and taking advantage of the chemistry that occurs in the few seconds which elapse between the points of injection and detection.This paper presents a progress report of this long-term study. Instrument a1 Developments In keeping with the spirit of FIA as developed by RiiiiCka and Hansen, we have aimed at simple, robust, low-cost automation. This has meant using a microprocessor for the computation and the development of detectors that are backed by modern, solid-state, digital electronic circuitry. One, with a number of advantages, has a chromatography valve as an inlet, uses stainless-steel tubing with Swagelok connections, has a variety of detectors and a constant head for the fluid flow. The sample injection is controlled by a microprocessor, which also arranges for the print-out of the peak height, peak width and the position of the peak maximum. Such an arrangement is very easy to assemble and program (the one used earlier, for a titrator, is easily adapted).2 It functions with a precision of about 1% and at best 0.3%.However, it is not ideal for the tasks we have in mind. Firstly, it is desirable to have a precision of about 0.1%. This, in principle, can be achieved by good algorithms and by an improved inlet system. It would also be advan- tageous if such an inlet system could be made automatic and be arranged to have a sampling rate of 200 h-l. Secondly, in seeking to exploit the chemistry to the full we need a system that can handle input from several detectors, and has a capability of extracting quantitative data by means which are, at present, unconventional.Before using a microprocessor on a problem of this sort one needs a very clear appreciation of the chemistry involved and in the nature of the signal to be obtained. Consequently, most of our recent instrumental work has been on the development of two detectors. There are a number of permissible permutations of apparatus. Photometric - Refractometric Detector In essence the flow cell is a tube 7 mm long and 1 mm in diameter. Through this cell light passes from a light emitting diode (LED) to a photodiode. The LED has a narrow (30 nm) band width, whereas the photo- diode is receptive to radiation over a wide region of the spectrum. The detector functions as a filter colorimeter, the wavelength of incident radiation being altered by changing the LED.The electronic back-up is by FET operational amplifiers. The signal is so noise-free that large deflections are obtained on a standard 1-V recorder from solutions that are 10 p.p.b. with respect to cobalt(I1) injected into a carrier stream of M 4-(2-pyridylazo)resorcinol (PAR) at pH 9. The material costs are less than $50, and the complete unit is very compact, amounting to a power pack and a small printed-circuit board. A very simple photometric detector has been d e ~ i s e d . ~ Plexiglas, PTFE or stainless steel have been used for the cell material.38 FLOW INJECTION TECHNIQUES Anal. Proc. When attempting to determine the sensitivity of the photometric detector, it was noted that a signal was obtained with extremely dilute solutions.This was different in kind to the photometric signal, and was soon identified with the refractive index of the sample. Further investigation showed that the sample plug, owing to the parabolic shape adopted during flow, acts as a lens, which may converge or diverge the light from the LED depending on the contours and gradients of the isohalines that are established as the sample and carrier mix. It is even responsive to temperature changes as a consequence of the temperature dependence of refractive index. It will be noted that this is a direct consequence of having an interface between sample and carrier, and also that it is a general effect which may be observed with many photometric detectors. It can be minimised or maximised. In the latter instance, the detector functions as a sensitive differential refractometer.At present we have not been able to compare its performance with a commercial refractometric detector in any meaningful way, but preliminary tests show them to be roughly comparable. Conductivity Detector We have also investigated conductimetric detectors, taking advantage of solid-state devices and employing a microprocessor to control the flow of current as well as to process the signal. The current model has a flow cell 1 cm long and 1 mm in diameter and is giving a very satisfactory signal. However, further tests are necessary before it is adopted for general use. Chemistry at the Interface Determination of Sulphate Krug et aL.4 have described an FIA method for the determination of sulphate via the, turbidity of barium sulphate. The carrier stream consists of barium chloride and poly(viny1 alcohol), which serves to hold the precipitate in suspension.However, in some applications there is a build-up of the precipitate, which leads to low precision and ultimately blocks the tube. A way of overcoming this problem is to use the washing capacity of the carrier and to exploit pH changes across the interfa~e.~ This last is achieved if the carrier is alkaline barium chloride in the presence of excess EDTA, and the sample of sulphate is acidic. Then, under the acidic conditions in the plug, barium sulphate will be precipitated, the precipitate being re-dissolved by the excess of alkaline EDTA in the carrier. Hence, the system is kept clean.EDTA also serves to reduce interference from metal ions, but phosphate, the barium salt of which is soluble under acidic conditions but insoluble in alkaline barium - EDTA, does interfere. The use of conditional constants assists in the selection of appropriate concentrations and pH of carrier and sample. Further consequences of using this pH gradient effect are an enhancement of the sensitivity by a factor of 1.8 and an improvement in the precision. In this application, relatively large changes of pH are employed and used to change the balance of equilibrium in a reaction (Bay2- + One might expect that pH-dependent redox reactions could be used similarly with some advantage. + 3H+ + BaSO, + H,Y-). The Determination of Mixtures of Metal Ions A more sophisticated approach to that exemplified by the determination of sulphate is to consider the effects of the pH gradient over the whole of the sample.For the purposes of the argument it is easiest to imagine a long plug of sample, initially acidic, in a carrier which is alkaline. The carrier diffuses into the sample to give a pH gradient which at its most extreme goes from the initial pH of carrier to that of the sample. Ultimately, the pH approaches that of the carrier. Now, if it is borne in mind that for a given metal ion - reagent combination the pH - absorbance curve is highly characteristic, then the change in absorbance across the sample plug that can be observed when a solution of metal ion is injected into a reagent solution of different pH is also highly characteristic. Also, although the detailed theory is complex, the peak profile is closely related to the pH - absorbance curves, which may be used to interpret qualitatively the sequence of reactions going on as the sample and carrier mix. Further, if the sample consists of a mixture of ions the reactions, in the presenceJaizuary, 1981 FLOW INJECTION TECHNIQUES 29 of an excess of reagent, are additive, so that from the information contained in the peak profile the components of the mixture can be determined quantitatively.This has been demonstrated for mixtures of lead and vanadium,6 and is further illustrated by the example of copper and manganese (Figs. 1 and 2). Q) 0 C m e a 'I Manganese I ' I ' I ' I 1 I 0 2 4 6 8 1 0 1 2 0.5 10.5 0.5 PH PH Fig. 1. pH - absorbance curves for copper(I1) - PAR and mangan- Manganese(I1) and ese(I1) - PAR under (a) static conditions and (b) FIA.copper(I1) 1 hT; 4 x M PAR. In this instance an extended pH gradient has been achieved by using universal buffer These experiments demonstrate the potential for performing multi-element analysis by The problem arises in extracting quantitative information from the peak profile. solution as the basis of the carrier stream. FIA. Fig. 2. Peak profiles of copper(I1) and mangan- ese(I1) mixtures over a pH gradient with PAR. Metal ion concentrations: ( a ) copper(II), 5 p.p.m., manganese(II), 2.5 p.p.m.; (c), (d) and ( e ) , copper(II), 5 p.p.m., manganese(II), 5 p.p.m.; (f) copper(II), 2.5 p.p.m., manganese(II), 2.5 p.p.m. (a) Sample stream, 5 x lo-* M PAR; (b) pH gradient stream, universal buffer, pH 0.5.Injected buffer, borax 0.012 5 M plus sodium hydroxide pH 10.5; injected buffer volume, 0.4 ml. Flow-rate, 0.5 ml min-l each stream. Tube length, 270 cm; diameter, 0.4 mm.30 FLOW INJECTION TECHNIQUES Anal. Proc. One of the procedures that we are experimenting with is to feed a series of peak profiles for standard mixtures into the microprocessor so that an unknown can be matched by one on file. Such a procedure is well suited to the microprocessor, and is feasible with FIA because of the speed with which a large number of standards can be processed and entered into the computer. Variations on the theme are also possible, and we plan to investigate the possibilities fully in the near future. Viscosity and Diffusion Coefficients In FIA the observed sample peak is dependent upon the difference in viscosity between the sample and the carrier.The principle sources of variation are in the time taken for the sample to reach the detector and in the peak height. In conventional FIA it is best to match the viscosities of sample and carrier in order to eliminate these effects. Failure to do so can sometimes result in a non-linear calibration graph. Following a preliminary experiment' we have investigated the possibility of measuring viscosity by FIA. The experimental part is easy. The microprocessor-controlled apparatus, described above, has been used in conjunction with a refractometer. Typical sample sizes are 6-30 p1 and the time for the determination is about 1 min.The apparatus is self cleansing and fully thermostated.* The carrier can be matched to the sample in order to ensure a satisfactory throughput and measurement. Thus, water, toluene, benzene and dimethyl- formamide have been used by us. For all systems so far tested, over the range 0-800 cp, a satisfactory calibration curve can be constructed (Fig. 3), but it is not an absolute method and it is now clear that chemical effects give rise to non-linear relationships. 2oo 180 I Y Q) a - v) \ .- i 0 10 2030405060708090 Glycerol, % 0 10 20 30 40 .E 12 10 8 ."L 2 0 10 2030 405060708 Glycerol, % V iscosity/cp l r -J* E 1 6 - .z 10 - -? 1 4 - g 12 - 8 - Y 9 6 - 1 . 3 J.L $160 0 0.2 0.6 1.0 1.4 1.8 " 1 2 3.,4 5 6 7 8 9 10 I .2 2.2 5.0 8.8 18.0 45.1 9 O p 1 t r 0 1 I 2 \ 2 10% Glycerol t 8 150 E .- %I40 a, Q 0130 c.' t .g 120 V .- .c110 I cn 0.4 0.8 1.2 1.6 -$I00 < (UlOOL ' I ' J 0 0.4 0.8 1.2 1.6 ,g 0 10 20 30 40 .E ( t/q 1 " V iscosi t ylcp 1.2 2.2 5.0 8.8 18.0 45.9 I , I I I 0 0.4 0.8 1.2 1.6 I- Viscosity/cp Log viscosity I- Viscosity/cp I- Log viscosity Fig.3. Injection of glycerol - water mixtures into water. Sample size, 30 p1; length of tubing, 110 cm; diameter 0.86 mm; flow-rate, 1.06 cm s-l; detector, refractometer. In principle, there are two theories that are appropriate; the oldest is due to Poi~euille.~ The sample can exert a viscious drag on the carrier and for constant conditions of a flow-rate, sample size and tube dimensions, the theory predicts a linear relationship between viscosity and the time taken to peak maximum.This relationship holds for many samples, and it is,January, 1981 HYDRODYNAMIC CHROMATOGRAPHY 31 in principle, an absolute method, although in practice one would always calibrate. The other theory is due to Taylor, who showed that at slow flow-rates in narrow tubes the dispersion of a sample is largely controlled by radial diffusion.1° His limiting conditions are easily achieved and plots of log viscosity versus peak height or the square root of (time to peak maximum) /viscosity veysus peak height are often linear. However, the theory suggests that what is being measured is the molecular diffusion coefficient and this does not provide an absolute method of determining viscosity, although there is an inverse relationship between viscosity and the diffusion coefficient for a number of systems. Both theories can be used to explain many of the results, but deviations occur especially when chemical reactions such as hydrogen bonding take place.From the point of view of Poiseuille’s theory confusion is caused if, by hydrogen bonding taking place to a varying extent during the course of the measurement, the viscosity of the sample changes. (For example, a graph of the viscosity of water - ethanol mixtures veysus composition passes through a maximum corresponding to a 1 : 1 molar ratio.) Taylor’s theory also is vitiated if the mixing process is affected by chemical reaction. Consequently, the value of FIA for the measurement of viscosity must not be overstated. However, in practical terms, when used with discretion it may have considerable value by virtue of its speed and small sample size.It is for this reason that we are continuing to work on the development of a fully automated, high-precision FIA system. Conclusions Apart from its inherent speed and simplicity FIA is attractive because it opens up the possibilities of novel analytical methods based on the interfacial region between sample and carrier. The chemistry involved is complicated, but simple considerations provide useful guidelines. (More quantitative treatments are possiblell but have not been discussed in this survey.) Obviously the programme for research is a long-term one, but so far the benefit has been in the development of new detectors and the realisation that in FIA experiments it pays to match the sample and carrier for temperature, ionic strength (both affect the refrac- tive index) and viscosity. It is hoped, in the next phase of the work, to develop a high- precision, fully automated apparatus that will be capable of a variety of measurements. The Science Research Council is thanked for Studentships to B.F. and P.S.; NATO grant No. 1492 is also gratefully acknowledged. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. References Betteridge, D., Anal. Chem., 1978, 50, 832A. Betteridge, D., Dagless, E. L., David, P., Deans, D. K., Penketh, G. E., and Shawcross, P., Analyst, Betteridge, D., Dagless, E. L., Fields, B., and Graves, N. F., Analyst, 1978, 103, 897. Krug, F. J . , Filho, H. B., Zagatto, E. A. G., and Jrargensen, S. S., Analyst, 1977, 102, 503. Baban, S., Beetlestone, D., Betteridge, D., and Sweet, P., Anal. Chim. Ada, 1980, 114, 319. Betteridge, D., and Fields, B., Anal. Chem., 1978, 50, 654. Betteridge, D., and RhiiEka, J., Talanta, 1976, 23, 409. Betteridge, D., Dagless, E. L., David, P., and Deans, D. R., “Handbook, Fourth SAC Conference on Analytical Chemistry, Birmingham, 1977,” Chemical Society, London, 1977, p. 42, Abstract No. 41. Poiseuille, J . L., C.R. Acad. Sci., 1840, 11, 961 and 1051. Taylor, G., PYOG. R. SOG. London, 1953, A219, 186. RfiiiCka, J., and Hansen, E., Anal. Chim. Acta, 1978, 99 37. 1976, 101, 409.

ISSN:0144-557X    

DOI:10.1039/AP9811800026

出版商:RSC    

年代:1981

数据来源: RSC

摘要:

January, 1981 HYDRODYNAMIC CHROMATOGRAPHY 31 Hydrodynamic Chromatography The following is a summary of one of the papers presented at a Joint Meeting of the Particle Size Analysis and Chromatography and Electrophoresis Groups held on December 5th, 1979, at the Linnean Society, Burlington House, London. Hard-sphere Model for Hydrodynamic Chromatography Systems S. M. F. Tavernier,tE. Nies and R. Gijbels Aspirant N F WO, Department of Chemistry, University of Antwerp ( U I A ) , Universiteitsplein 1, B-2610 Wilrijk, Belgium In recent years there has been increased interest in hydrodynamic chromatography (HDC), from both the theoretical and practical points of view. This technique enables particle32 HYDRODYNAMIC CHROMATOGRAPHY Anal. Proc. sizing and particle separation based on the fact that the retention time of the injected particles depends on their hydrodynamic radius.Various HDC theories have been developed. Dimarzio and Guttmanl introduced a theory taking into account hydrodynamic factors only. Particles are excluded, for structural reasons, from a part of the capillary and will therefore move with a velocity greater than that of the solvent, the latter being free to move over the whole width of the capillary. The velocity of the particles with respect to the solvent will be greater than unity. Fig. 1 shows the behaviour of a spherical colloidal particle in a cylindri- cal capillary. r t Fig. 1. Schematic diagram of a spherical colloidal particle in a Poisseuillic flow through a long cylindrical capillary. Prieve and Hovsan2 extended the theorv of Dimarzio and Guttman bv introducing elect ro- static and Van d&- Waals - London forces i n addition to the chromatogiaphic effect aescribed above.Both theories deal with particles that are assumed to be hard spheres. When applying HDC, it is of great importance to have a good theory, which can be verified. Normal colloidal systems are often poly- disperse and even non-spherical or not hard. In order to evaluate the theoretical approaches of HDC it is preferable to perform experiments with a hard-sphere model system. The first stage in this work was to find monodisperse, hard-sphere colloids. Afterwards HDC apparatus had to be assembled, and checked thoroughly. In a final step, combination of both the HDC set-up and our model system will enable us to evaluate the theoretical models proposed in the literature; this final part has only recently begun.When searching for monodisperse colloids, one obviously considers biopolymers and synthetic polymers. Biopolymers especially exhibit a high degree of monodispersity owing to biogenesis. The same holds for lattices prepared under special conditions or after very careful separation of a small fraction. The disadvantage of these systems is that they cannot be described as a hard sphere. This problem depends on the degree of swelling of the colloid, which is very much affected by the degree of cross-linking and, for instance, the nature of the solvent. Hence, it is preferable to find solid colloids that do not suffer from the disadvantages described above.According to Stober et al.3 and I l e ~ - , ~ it is possible to prepare quasi-monodisperse hard spheres synthetically. We made a comparison between such monodisperse silica colloids and some commercial carbon blacks, and will indicate some differences between both types of colloids. The silica dispersions are prepared by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol in the presence of water and small amounts of ammonia. It is a fast reaction giving rise to particles with narrow size distribution functions and radii between 0.05 and 0.7 pm, depending on the composition of the reaction mixture. I t can be synthesised in large amounts without difficulty. Two basically different types of silica colloids were prepared in our laboratory, a hydrophilic colloid, consisting of polycondensed TEOS, and a hydrophobic one, prepared by esterification of free silanol groups at the particle surface with stearyl alcohol at higher temperature. Particles coated in this way can be dissolved In practice, however, large problems can arise.A certain porosity and compressibility are present.Jamtary, 1981 HYDRODYNAMIC CHROMATOGRAPHY 33 easily in cyclohexane and benzene, upon addition of Aerosol OT or some polymers, giving rise to stable colloids. The size distributions of the prepared silica dispersions were obtained with transmission electron microscopy (TEM) and an automatic planimeter. The distribution functions were compared with those found for some commercial carbon blacks. We used a diaphragm pump (Orlita DMP) and 3.60-m stainless-steel tubing (Lichroma, inside diameter 6 mm) in combination with an on-column septum injector. The column was filled with a bed of glass particles having a radius of 29 5 3 pm, obtained with a wind-sieving procedure.It should be stressed that the column-packing procedure is essential; very careful packing has to be carried out, giving rise to a minimal height equivalent to a theoretical plate (HETP), as will be discussed later. Two detectors were used, a refractive index detector and an ultraviolet detector, types 1107 LDC and Schoeffel, respectively. The refractive index detector was used to obtain very accurately the start of the elution. During the injection a pressure wave is produced. As the refractive index of a solvent is very sensitive to com- pression, the exact moment of injection can be determined very accurately.Ultraviolet detection was used for monitoring the colloidal particles and the solvent front. The latter was detected, using a molecular marker, sodium dichromate, at 372 nm. Both detectors were connected to a linear two-pen recorder. The characteristics of the experimental set-up were checked in order to obtain information on the quality of the apparatus. The Poiseuille behaviour in the column was tested by measuring the relation between the flow-rate and the pressure difference over the column. A linear relationship was found up to 150 bar. The Reynolds number was smaller than 0.2 in all instances, so that no turbulence occurred. Another point of interest is the determination of the dimensions of the equivalent cylindrical capillary.In practice, however, a column does not contain cylindrical capillaries but it can be described as an assembly of cylindrical capillaries with equivalent radius, Re,, and equivalent height, Heq. We determined the interstitial volume in the column in order to obtain information on those quantities and information on the packing efficiency. This can be obtained by comparing the masses of the dry and wet columns. The packing efficiency, assuming ideal spherical packing of monodisperse glass spheres, was about 90%. Small deviations from 100% can occur, owing to the non-monodispersity of the packing material, but it is thought in this laboratory that more effort could be made to improve this packing efficiency.The equivalent radius of the capillary was found to be 5.4 pm. The equivalent length was 6.32 m for a 3.6-m column, and 37 400 equivalent cylindrical capillaries are contained in the column. By using these values a good theoretical value can be calculated for the function relating the flow-rate and the pressure difference. Experiments with sodium dichromate only were performed in order to obtain information on the HETP value. At 100 bar, we found that the number of plates for a 3.60-m column was 8411, the HETP being 428 nm. If the packing could be improved the HETP could be decreased by up to 200-300 nm. Some variations in HETP were observed as a function of flow-rate; this factor will be discussed below. As a general judgement on the instrumental set-up used by us so far, we can state that it is adequate but can certainly be improved, especially by increasing the packing efficiency from 90yo to 96% or more.In this last section, some preliminary experimental results are presented that were obtained with the column described above. The hydrophilic silica colloid (0.206 g of silica in 25 ml of water) was stabilised by adding Aerosol OT up to 6.8 x moll-l. The radius of the silica particles was 0.24 0.01 pm and the molecular marker was sodium dichromate solution at a concentration of 5.0 x The eluting agent was aqueous AOT solution with the same AOT concentration. A good resolution was obtained between the solvent (i.e., molecular marker) peak and the peak corresponding to the colloid. The RF, HETP, and HETP, were measured from the injection of 30-pl samples at different flow- rates.Its value decreased initially with increasing flow-rates, reached some minimum and possibly increased or remained constant at higher flow-rates. The same inconsistent behaviour is found for HETP, and HETPm. Noel et aL5 found that the values for HETP, and HETP, could be different, depending on the concentration. However, it is difficult to explain the remarkable increase of HETPm at higher flow-rates. This may indicate that at higher flow-rates another separation mechanism is present. The second part of our work was to assemble a suitable HDC unit. All theories are developed for cylindrical capillaries. g per 25 ml. Unusual behaviour of the RF compared with pressure difference was noted. The minimum is found to be 80 bar.31 EQUIPMENT NEWS Anal. Proc. As an over-all conclusion we can say that further improvement of the packing efficiency is essential if we are to carry out very accurate HDC work. HDC with silica spheres revealed unusual behaviour of R F , HETP, and HETP, as a function of flow-rate and an essential difference between HETP, and HETP,. This behaviour indicates that other mechanisms or interactions not previously known or taken into account may be important. acknowledged. The support of the Belgian National Fonds voor Wetenschappelij k Onderzoek is gratefully References 1. 2. 3. 4. 5. Dimarzio, E. X., and Guttman, C. M., Macvovnolecules, 1970, 3, 131. Prieve, P. C., and Hoyson, P. M., J . Colloid Interface Sci., 1978, 64, 201. Stober, W., Fink, A., and Bohn, E., J . Colloid Interface Sci., 1969, 26, 62. Iler, R. K., U.S. Pat., 2 801 185. Noel, R. J., Gooding, K. M., Regnier, F. E., Ball, D. M., Orr, C., and Mullins, M. E., J . Chromatogv., 1978, 166, 373.

ISSN:0144-557X    

DOI:10.1039/AP9811800031

出版商:RSC    

年代:1981

数据来源: RSC

摘要:

EQUIPMENT NEWS Anal. Proc. Equipment News Scanning Electron Microscope The SEM 505 features high-sensitivity, fast- response detectors in a group of four beneath the final lens. Each is readily interchangeable for use for backscattered electrons or cathodo- luminescence. They are linked to an external photomultiplier - pre-amplifier by fibre optic connections. A similar arrangement beneath the specimen is used for transmitted electrons. Other detectors measure specimen current and X-ray production. An EDAX PV9100 energy-dispersive spectro- meter provides simultaneous elemental analysis in the atomic number range 11-92, while a microprocessor-based Microspec WDX-2A sup- plies high resolution qualitative and quantita- tive analyses of all elements down to beryllium. A Wedax option co-ordinates energy and wavelength dispersive X-ray analysis.SEM image analysis can be provided by an Omnicon Sigma 200. Pye Unicam Ltd. Insert E501 on the Reader Enquiry Service form for further information. Scanning Electron Microscope The Stereoscan 250 offers continuously variable resolution by means of a final aperture of continuously variable size. This enables opti- mum resolution for any specific set of parameters or it can vary the depth of field. Resolution in the secondary electron emission mode is better than 6 nm. An oil-free turbomolecular pumping option is also available. Cambridge Instrument Co. Ltd. Insert E502 on the Reader Enquiry Service form for further information. Electron Beam Microfabricator The EBMF-6 is a flexible, computer-controlled electron-beam microfabricator used to delineate semiconductor device patterns. Operation is linked with a DEC PDP- 11 computer, using the RSX-11M system. The EBMF-6 system program, designated QSYS, gives conversa- tional user control of the system.The deflection system is automatically calibrated to the pre- cision of the laser stage and the large field size and high resolution means fewer movements are required to construct layer chips. The optical column permits the writing of patterns in field sizes 0.5-3.2 mm, with a selectable 12-15 bit data field. Insert E603 on the Reader Enquiry Service form for further information. Cambridge Instrument Co. Ltd. Colour Graphics System System 45C is a desk-top computer with a, colour graphics display, having available 4 9 13 colours.Programmable in enhanced BASIC, it contains a hand-held light pen with which to draw on the screen, and a thermal printer can prepare a monotone copy of any display from the screen. Hewlett-Packard Ltd. Insert E504 on the Reader Enquiry Service form for further information.January, 1981 EQUIPMENT NEWS 35 Image Analyser The Quantimet 800 image analyser features fully automatic operation. Detectors provide full-speed automatic boundary-finding algor- ithms which, with scanners designed for quantitative work, give improved accuracy. The system is programmable in BASIC or PASCAL. An illustrated leaflet is available. Cambridge Instrument Co. Ltd. Insert E505 on the Reader Enquiry Service form for further information. Thermal Analysers Using the thermal analysis technique, routine measurements such as purity, crystallinity, kinetics, specific heat and liquid fraction can be carried out automatically by the Mettler TA2000,4.This differential scanning calori- meter is controlled by a microcomputer and processor. Being in a modular form, it can be built into a fully automated system. The Rllettler TA2000B is a low temperature instrument with excellent base-line stability down to - 170 "C and has a usable range of - 150 to + 150 "C. Cooling as well as heating is controlled to economise in the use of liquid nitrogen. The Mettler TA2000D is capable of operation up to 1200 OC, or, with an alternative furnace, up to 1600 "C. The Mettler 2OOOC is capable of carrying out simultaneously differential scanning calori- metry and thermogravimetry up to 1200 "C.The alumina furnace is generally corrosion- resistant, but a special furnace is available for difficult atmospheres. An accessory furnace permits operation up to 1600 "C. The balance, remotely controlled, can detect mass changes of 10 pg in samples in the gram range. Insert E506 on the Reader Enquiry Service form for further information. MSE Scientific Instruments. Data-processing and Recording Systems The BS 2000 series is designed to process and report data supplied as analogue signals on two independent channels with ten voltage scales (10 mV-10 V). Sampling rates can be varied from 50 ps to 1 h per point. The plotter operates in strip-chart or X - Y mode. The Model BS 2120 is designed for general laboratory use, and is programmable to carry out a variety of basic arithmetical operations.Bryans Southern Instruments Ltd. Insert E507 on the Reader Enquiry Service form for further information. Amplifier A diffferentiator amplifier module, Model 13-4615-71, is specifically designed to aid bio- physical measurements. Being compatible with Series 2000 recorders and 51 Series biophysical monitoring systems, Model 13-4615-7 1 deter- mines the rate of change of an input function to derive, for example, blood acceleration from blood flow or eye velocity from eye position during electro-nystagmogram recordings. It can also be used directly as a general purpose d.c. amplifier with a maximum sensitivity of 100 mV full scale. Gould Instruments Division. Insert E508 on the Reader Enquiry Service form for further information. Processor Hi-Comp 32 is a 32-bit array processor for high- speed Fourier Transform - infrared spec- troscopy.Fourier transform calculations take less than 1 s, and other applications range from real time GC/IR to high-resolution gas-phase spectroscopy . Insert E509 on the Reader Enquiry Service form for further information. Bio-Rad Laboratories Ltd. Blood Gas Analyser The ABL3 Acid - Base Laboratory is a prograni- mable micro pH - blood gas analyser, measuring pH, pCO,, PO,, haemoglobin and barometric pressure on a 125-p1 capillary sample. Other parameters can be calculated, and other func- tions such as rinsing and calibration are also performed automatically. Special programmes are also available for use with the built-in computer.36 Anal.Proc. EQUIPMENT NEWS Radiometer A/S. Insert E510 on the Reader Enquiry Service form for further information. X-ray Microanalysis System System 860, an advanced energy dispersive analyser, now offers analytical facilities for electron energy loss spectrometry as well as scanning and transmission electron microscopy. Hardware - software interfaces for EELS per- mit pulse counting a t 100 MHz and quantitative analysis of the data obtained. Facilities are available for SEM - microprobe analysis of rough surfaces, and an integrated automation system that allows control of spectrometers and the specimen stage with simultaneous acquisi- tion of data processing from both energy- and wavelength-dispersive spectrometers. Link Systems Ltd. Insert E511 on the Reader Enquiry Service form for further information.Analytical System A system involving two gas chromatographs and a mass spectrometer is designed to trace and identify organic compounds in the nanogram range. The first, relatively crude gas chromato- graph separates the mixture into groups of molecularly similar compounds, which are sampled by an electronic flow controller. A molecular group weighing less than the “cut- off” figure is stored in a “cold-trap,” while only a fraction of those weighing more than that figure is stored, the rest being vented. The second gas chromatograph next separates the stored molecules, which are then identified on the mass spectrometer. General Electric Company of the USA. Insert E512 on the Reader Enquiry Service form for further information.Oxygen Monitor A portable trace oxygen monitor made by Re- search Inc. of America can be used for various ranges between 0-1 p.p.m. and 0-2000 p.p.m. A stable R I - Hersch fuel cell with a yield of approximately 93% converts the oxygen in a gas sample into a 10-mA signal for each p.p.m. of oxygen. Loss of moisture from the electrolyte is prevented by a humidifier and the cell, after charging, has a detection life of 10000 p.p.m. total of oxygen. Insert E513 on the Reader Enquiry Service form for further information. Ultraviolet Detector The 80-800 Preparative Liquid Chromato- graphy - Ultraviolet Detector, by virtue of its low sensitivity of 1.8 x g ml-l of toluene a t 254 nm, can be used with preparative liquid chromatographic columns, with peaks in the milligram to gram range.The instrument uses a fixed wavelength, 254 nm, with a photodiode sensor, and with a nominal path length of 0.1 mm is designed for flow-rates from 1 to 500 ml min-l. Astro Technology Ltd. Gow-Mac Instrument Co. (UK) Ltd. Insert E514 on the Reader Enquiry Service form for further information. Planchet Changers Two Planchet Changers, made by Berthold, for measuring very low levels of beta-emitting radioisotopes now possess efficiency2 back- ground-l ( E2 B-l) superior to liquid scintillation counters. The LB 750L accepts 25 or 50mm diameter planchets, with the anticoincidence counting tube using the standard PI0 gas a t a rate of 15 ml min-’. Larger samples, up toJanuary, 1981 EQUIPMENT NEWS 37 200 mni diameter, can be counted in the LB 760GD model, again with short gas purging times. Insert E515 on the Reader Enquiry Service form for further information.Laboratory Impex Ltd. Standard Absorbance Filters A set of nine neutral density glass filters cover- ing the range 0-0.3 nm possess excellent long term stability and will fit most spectrophoto- meters that accept 10 mm rectangular cells. The filters have been ultimately calibrated to NPL standards. Insert E516 on the Reader Enquiry Service form for further information. Pye Unicam Ltd. Protein Testing Kit The protein testing kit uses Coomassie Brilliant Blue G250 in order to complex total protein almost instantaneously. This causes a shift in the absorbance maximum from 465 to 595 nm, the amount being proportional to the protein present.Each test uses 0.1 ml of CSF or urine and 5 ml of dye reagent. Bio-Rad Laboratories Ltd. Insert E517 on the Reader Enquiry Service form for further information. Pressure Filter Holder Three models of a lightweight stainless steel pressure filter holder for microfiltration use are available to fit filter diameters of 142, 200 or 293 mm. A seamless filter support gives a higher flow-rate. Anderman & Co. Ltd. Insert E518 on the Reader Enquiry Service form for further inform ation. Laser Wavelength Meter The IVavemeter measures the absolute wave- length of any CTV laser operating in the range 0.4-4 pm. Model WA-20 measures the vacuum wavelength of the input throughout the whole of the above range by the addition of an optional infrared assembly, to an accuracy of 1 p.p.m., with the display reading to 0.001 nm in the visible or 0.01 cm-l in the infrared.The Model WA-10 is designed for a narrower 5 p,p.m. Cryophysics Ltd. Insert E519 on the Reader range, 0.4-1 ,urn, with an accuracy of Enquiry Service form for further information. Dissolved Oxygen Meter The Model 7130 measures oxygen in p.p.m. or yo saturation, and operates from a 9 V dry battery or a mains adaptor. The screw-in replaceable oxygen cell requires no maintenance. Kent Industrial Measurements Ltd. Insert E520 on the Reader Enquiry Service form for further information. Infrared Thermometer The Wahl DHS-16X portable, non-contact, infrared thermometer has a range of 0-1000 "C with a 1" resolution, accuracy to 10.5% full scale and sensitivity of 0.5 "C.An enclosed optical sight defines the area being measured and a Maxi-Temp automatic peak hold is included. Wahl International. Insert E521 on the Reader Enquiry Service form for further information. pH Meter Model PTM1 will measure pH, temperature and millivolts to a resolution of 0.01 pH, 0.1 "C and 1.0 mV, and is battery operated. An optional battery eliminator is available. Insert E522 on the Reader Enquiry Service form for further information. Petracourt Ltd. Digital Thermometer A lightweight digital thermometer covers the range from - 100 to 200 "C, with a range of probes, such that it can be used for general liquid or solid - semi-solid immersion, surface contact, air temperature, battery acid tempera- ture or fridge - freezer temperature nieasure- ments.All probes are accurate to 5 0 . 3 "C over the complete range. Insert E523 on the Reader Enquiry Service form for further information. Scientific and Medical Products Ltd. Digital Thermometer The 1001 Series digital thermometer covers the range from -30 to 450 "C with an accuracy of &-0.3yo on the last digit and resolution of 1.0 OC, and is designed for use with a variety of NiCr/ NiAl thermocouples. A battery life of 500 h can be obtained with the manganese - alkaline cells. Use of a Model DX3 Differential Converter converts the 1001 to a direct differential temperature instrument. Jenway Ltd. Insert E524 on the Reader Enquiry Service form for further information.EQUIPMENT NEWS Anal. Proc. 38 Soap Film Flow Meter A precision soap film flow meter, the SF-11, can measure gas rates down to 0.1 ml min-l with _I 0.2 yo accuracy.Three models are available, with a range of flow-rates. The gas under test passes through a vertical glass tube of known capacity, carrying an internally generated 0.1 mm thick soap film past stop and start photoelectric detectors, with the time recorded by a quartz digital timer. Horiba Instruments Ltd. Insert E525 on the Reader Enquiry Service form for further information. Balances Two electronic top loading balances are announced, the Model 1206MP with a range of 1200 g and readability of 0.1 g, and the Model 1216MP with dual ranges of 120 g and 1200 g with readabilities of 0.01 g and 0.1 g, respect- ively. Insert E526 on the Reader Enquiry Service form for further information.Sartorius Instruments Ltd. High Pressure Valve Fittings Sno-Trik high pressure fittings in 316 stainless steel provide threadless connections for service up to 600001bin-2, and are usable with corrosive fluids, with high safety factors. Sizes are 1/4, 3/8 and 9/16in. The Sno-Trik Valve range with a selection of port fittings is available in the same sizes. Insert E527 on the Reader Enquiry Service form for further information. Manchester Valve & Fitting Co. Ltd. Alloy Valves Nupro poppet-type check valves for use with corrosive fluids are available in titanium, Hastelloy C, Carpenter 20 and Inconel. End connections are available in 1/4, 1/2 and 3/4 in female NPT and Swagelok tube fittings. Pres- sure ratings for 1/4 and 1/2 in valves are 3000 lb in-, (20600 kPA) and for 3/4 in 2000 lb in-2 (13 700 kPA) .Temperature range, with Viton seals, is from -40 to 204 “C. Techmation Ltd. Insert E528 on the Reader Enquiry Service form for further information. New Products Aminex high capacity and Dowex low capacity ion-exchange resins are useful for the separation of low concentrations of metal cations and various anions, respectively. For example, Cu, Zn, Ni, Co and Cd were rapidly separated in concentrations of 5 p.p.m. using Aminex A-4, and U isolated a t less than 6 p.p.m. Anions F, C1, NO,, Br, SO, were separated prior to coulimetric detection on Dowex low capacity 16% crosslinked resin a t concentrations down to 5 p.p.m. Insert E529 on the Reader Enquiry Service form for further information. Dilut-it analytical concentrates enable fresh solutions for titrimetry, photometry and AAS to be prepared quickly and accurately merely by dilution.The concentrates are accurate to Insert E530 on the Reader Enquiry Service form for further information. Bio-Rad Laboratories Ltd. & 0.1 yo. J. T. Baker Chemicals B.V. Literature A leaflet describes the Process/5000 Series of total carbon - total organic carbon analysers developed by Ionics Inc. High-temperature combustion and ultraviolet oxidation analysis methods are offered. Many applications are discussed. Techmation Ltd. Insert E531 on the Reader Enquiry Service form for further informa tion. An Applications report by Spectrametrics Inc. on “Analysis of Major and Trace Compon- ents in Stainless Steel, Nickel, Copper Alloys and Monel Metals” describes the use of Spectra- span 111, a d.c.plasma emission spectrometer. Techmation Ltd. Insert E532 on the Reader Enquiry Service form for further information. A data sheet, No. 159-A, describes the analysis of benzene and toluene in petrol to ASTM D3606 using a Carle Series-S analytical gas chromato- graph. Techmation Ltd. Insert E533 on the Reader Enquiry Service form for further information.Janunvy, 1981 ANALYTICAL PROCEEDINGS 39 Analytical Chemistry I ndust rial Travel Fellows hi ps The Trustees of the Analytical Chemistry Trust Fund have decided to offer a limited number of Travel Fellowships to enable young analytical chemists to attend important major analytical chemistry meetings in Europe and the USA in 1981. Candidates should be members of the Analytical Division of the Royal Society of Chemistry and should be less than 30 years of age a t the closing date for the receipt of applica- tions.They should also be in full time employ- ment in industrial, research association or government-funded laboratories. Candidates for the Fellowship will be en- couraged to submit papers for presentation a t the meeting they wish to attend; in addition they will be expected to make contact with major manufacturers of analytical instruments and equipment in the area.of the conference or to visit specialist institutions where analytical chemistry plays a major role. They will be expected to have the full support of their employers and i t will be an advantage if arrangements could be made for them to visit another industrial company in an allied field situated in the area of the conference. On completion of the Fellowship recipients will be required to make a detailed report to the Trustees of the use to which they have placed the Fellowship and the advantages which have accrued from its award.It is likely that sum- maries of these submissions will be published in Analytical Proceedings and recipients might be invited to present a verbal report a t one of the Division’s Group or Regional Meetings. Applications for the Fellowship should include detailed proposals of the purpose to which it will be placed should i t be awarded and applicants should also include statements from their employers that they would support the applica- tion. Further details of these Fellowships can be found in Anal. Proc., 1980, 17, 550. Closing date for the receipt of applications by the Secretary of the Analytical Division, Royal Society of Chemistry, Burlington House, London, W1V OBN, is February 28th, 1981. DIGESTION VESSELS Solve the problem of dissolution. Valtech ptfe lined digestion vessels can be used up lo 250°C and will withstand pressures of over 100 bars with considerable safety margin.The stainless steel vessels and caps are machined from numbered billets which have been shown to be free from flaws by ultrasonic testing, and a test certificate is provided with each vessel. Replacement plfe liners are always available. VALTECH PLASTICS CASTLEGARTH WORKS, THIRSK, N.YORKS. ENGLAND. relenhone: Thirsk (08451 22184 A401 for further information. See page 44 ANALYTICAL SCIENCES MONOGRAPH No. 5 Dithizone by H. M. N. H. Irving The author of this volume has gathered together a body of historical and technical data that will be of interest to many practising analytical chemists. Brief contents The Properties of Dithizone; Metal - Dithizone Complexes and Their Formulae; The Photo- chemistry of Metal Dithizonates; The Extrac- tion of Metal Dithizonates; The Less Familiar Dithizone Complexes; Organometallic Dithi- zonates; Practical Considerations; Some Additional Applications of Dithizone; Some Unresolved Problems; Bibliography. Hardcover 11 2pp 8%” x 53” ISBN 0 85186 787 1 f 12.50 THE ROYAL SOCIETY OF CHEMISTRY, Distribution Centre, Blackhorse Road, Letchworth, Herts., SG6 1 HN

ISSN:0144-557X    

DOI:10.1039/AP9811800034

出版商:RSC    

年代:1981

数据来源: RSC

摘要:

40 CORRESPONDENCE Anal. Pvoc. Correspondence Correspondence is accepted on all matters of interest to analytical chemists. Letters should be addressed to the Editor, Analytical Proceedings, The Royal Society of Chemistry, Burlington House, London, W1 V OBN. Safety in Analytical Laboratories Sir, As the preamble to Dr. Price’s article on “Safety Aspects of Analytical Atomic Absorp- tion” (Analytical Proceedings, 1980, 17, 402) invites correspondence, I feel moved to accept the invitation. Safety in operation It is common practice in my laboratory to use the air - hydrogen flame supported on a three- slot Boling burner head to determine low levels of tin in canned beverages. This combination gives us the maximum sensitivity for tin with the minimum of sample preparation, providing a limit of detection and precision of analysis of 0.5 p.p.m.on samples diluted five-fold with water. Dr. Price’s dogmatic statement that “In lighting the flame, the oxidant must be turned on first; in extinguishing, the fuel must be turned off first” is utterly wrong for the safe use of air - hydrogen. In fact, the reverse procedure should be used. Hydrogen should be ignited without air flowing, to prevent the almost inevitable flash-back of the pre-mixed gases. If, on extinguishing the flame, the hydrogen is switched off first, the flame speed of the mixture increases as the mixture weakens, and with a Boling burner there will always be a flash-back a t some stage in the proceedings. If, on the other hand, the air is turned off first, there will be no explosive mixture in the chamber and the combustion of hydrogen will be supported on the burner head as a diffuse flame, so that sub- sequent interruption of the hydrogen flow will merely extinguish the flame with no possibility of a flash-back. In the early days of our experience with AAS we used a corrosion-proof PTFE nebuliser needle which, after a couple of times, proved very much not to be flash-back proof, this after following the manufacturer’s instructions, iden- tical with those quoted by Dr.Price, for manipu- lating the air - hydrogen flame. The reverse pro- cedure which I use is, of course, well nigh impossible to operate with the “safe” automatic gas boxes. I obtain best peace of mind by using a manual box and common sense. On reflection, the only gas mixture of those quoted by Dr.Price in Table I that is safe with the recommended procedure is air - acetylene, with the exception of air - propane (does anyone use air - propane today ?). With any acetylene mixture, the interruption of the oxidant, be it air or nitrous oxide (easier to write than dinitrogen oxide) is perfectly safe; no explosion will occur, it is just messy supporting a diffuse acetylene flame on any burner head. I therefore venture to suggest that this section as set out by Dr. Price, and by all manufacturers in their recommended procedures, is really only applic- able to acetylene flames. Although Dr. Price has quoted the standard table of flame speeds, he has not shown that hydrogen flames behave differently from acetyl- ene flames. As I have suggested, Pye Unicam are not alone in this failing, indeed one manufac- turer has intimated to me that hydrogen flames are potentially more hazardous when used with the common recommended procedures and should therefore not be recommended for use ! Designing for safe operation A recent experience with a semi-automatic gas box has further disturbed my peace of mind, as well as the peace in our new laboratories. I was working with the nitrous oxide - acetylene flame when there was a failure in the mains electricity supply, which caused the solenoids governing the fuel and oxidant supplies to close (built-in fail-safe design) with a consequent flash-back and unpleasant explosion causing the burner head to shoot out of its holder (although it was held by the safety wires).I suggest that more thought is required in the design of such gas boxes. I know that Dr. Price does say that, with provisos, “the gas box is unlikely to be totally fool-proof”; this fool, who is also a very busy operator who appreciates any helpful aid, still believes in manual boxes and common sense. Chernicnl technique Dr. Price again indulges in a dogmatic state- ment, this time that “the actual amount of handling can, of course, be reduced by use of an auto-sampler.’’ Not so! This is the typical comment of the salesman who has a gimmick to sell. In fact, the use of an auto-sampler in-January, 1981 OBITUARIES 41 creases the handling of samples because of the extra stage required in filling the cuvettes of the sampler from the glassware that would other- wise be used directly in manual operation following whatever means of sample preparation was employed. Indeed, the use of an auto- sampler also increases the risk of contamination Dr.W. J. Price replies-Mr. Hill raises some interesting points for discussion in his letter, but I am afraid I cannot agree with much that he says. Let us take the main issues: L‘se of hydrogen flames For a flame system to be safe, it should be possible for either fuel or oxidant to be turned off or to fail without an explosion resulting. This is implicit in my paragraph ( i ) under Safety in Operation, where it is stated ‘ I . . . when the flame is being extinguished each gas should flow through the burner at a rate greater than flame propagation.” So the user should be able to turn either off first.But it is clearly better to turn off the fuel first for the following reasons: (a) the fuel gas remaining in the spray chamber creates a potentially dangerous condition ; hydrocarbon fuels without oxidant burn with an unpleasant smoky flame. If a system does not conform to the above it is potentially dangerous (as Mr. Hill appears to have discovered). We a t Pye Unicam, and evidently the manufacturer to whom he refers, would recommend that the multi-slot burner be used only with the gas mixtures for which it is intended : air - acetylene, air - propane and possibly hydrogen-based diffusion flames. The safety factor is much reduced if this burner is used with pre-mixed air - hydrogen both be- cause the expansion effect is low and because gas velocity through the larger slot area is greatly reduced.Safety from explosion in this case probably relies mostly upon the quenching effect a t the burner slot. (Incidentally, it is now many users’ experience that the analytical per- ( b ) of samples by bringing them into contact with more surfaces. W. H. Hill Research and Development Division, Metal Box Limited, Denchworth Road, Wantage, OX12 9BP formance of the multi-slot burner has little to recommend it over a well designed, much safer, single slot.) We therefore do not know what Mr. Hill means by “hydrogen flames behave differently from acetylene flames.” Of course, flow-rates are different but the safety principles are the same. Designing f o r safe opevation Gas boxes on the market may provide users with some choice as to the safety features they wish to incorporate. However, most manufac- turers now produce a system that includes all the facilities a safety-conscious user would expect, including totally safe shutdown under all circumstances of supply failure. Chemical technique I referred to “the actual amount of handling” and this should not be confused (as Mr. Hill has done) with the number of operations. A flame auto-sampler may (though does not necessarily) incur one extra operation, but the amount of time for which the sample flasks and instrument capillary would otherwise be handled should certainly be reduced. An auto-sampler for use with an electrothermal atomiser reduces both handling time and the number of manual opera- tions. I do not believe that, from either safety or accuracy viewpoint, these devices can justifiably be called a gimmick (though they may be, on occasion, dogmatically). W. J. Price Pye Unicam Ltd., York Street, Cambridge, CB1 2PX

ISSN:0144-557X    

DOI:10.1039/AP9811800040

出版商:RSC    

年代:1981

数据来源: RSC

摘要:

January, 1981 OBITUARIES 41 Obituaries In the October issue (p. 447) we announced the death of Mr. Peter John Burnill who died, aged 48, on June 30th, 1980. Peter Burnill was employed by Hickson and Welch for some 25 years, commencing his analytical career as a microanalyst, after obtaining his degree in Chemistry at the University of Leeds. He was a well respected and active member of the North East region of the Analytical Division of the Royal Society of Chemistry, serving as committee member, Assistant Secretary and Honorary Secretary. He resigned as Honorary Secretary following the death of his wife, Barbara, in 1979. His many friends and col- leagues in the Analytical Division express their deepest sympathy to Mr Burnill’s two sons and daughter. We deeply regret to announce the death of Dr. D. N. Raine, Chairman of the Midlands Region of the Analytical Division.

ISSN:0144-557X    

DOI:10.1039/AP9811800041

出版商:RSC    

年代:1981

数据来源: RSC

摘要:

42 AD DISTINGUISHED SERVICE AWARD Anal. Proc. Rank Hilger Spectroscopy Prize The Rank Hilger Spectroscopy Prize is an be awarded for any contributions to analytical annual award for young spectroscopists who atomic spectroscopy. The 1980 prize was are under 30 years of age a t the end of the. year awarded to M. R. Cave, of the Sheffield City for which the prize is awarded. The prize may Polytechnic, for his work “The Development ofJanuary, 1981 NEW BRITISH STANDARDS Plasma Torches and Optimisation of Inductively Coupled Plasma Sources for Atomic Spectro- Applications are invited for the 1981 prize, which has a value of k75, part of which is to be used for the purchase of a book(s) for presenta- tion a t the AGM of the Atomic Spectroscopy Group. Intending candidates should (1) be under 30 years of age on December 31st, 1981 ; (2) be resident in the United Kingdom; (3) submit, before May 31st, 1981, a summary of about 500 words, describing their various contri- butions to the theory and/or practice of atomic spectroscopy, with particular emphasis on the range of their work. This summary should be accompanied by documentary evidence of the candidates work, either in the form of copies of internal reports or publications.The name of two referees, one of whom has been associated with the work submitted, must also be given. The Selection Committee would also be pleased to consider applications brought to their attention by senior members of an establishment on behalf of candidates who could comply with the above criteria. Short- listed candidates may be required to submit a more detailed account of their work. The award will be judged on the basis of the candidate’s contribution to analytical atomic spectroscopy.Relevant techniques include atomic absorption, atomic fluorescence, atomic emission and X-ray fluorescence. The work may cover theoretical aspects, applications, instrumental modification, acces- sories, improvements in technique or data handling. Applications from industrial estab- lishments are particularly welcome and due allowance is made by the selection committee for the ease or otherwise of the candidates contribution(s). The contribution(s) need not have been published and candidates wishes with respect to publication will be respected. Applications should be addressed to the Honorary Assistant Secretary, Atomic Spectro- scopy Group, Analytical Division, The Royal Society of Chemistry, Burlington House, Picca- dilly, London, W1V OBN. scopy.” 43

ISSN:0144-557X    

DOI:10.1039/AP981180042b

出版商:RSC    

年代:1981

数据来源: RSC