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ANPRDI 22(1) 1-36 (1985) ISSN 0144-557X Analytical Proceedings Proceedings of The Analytical Division of The Royal Society of Chemistry Hon. Secretary R. Sawyer Hon. Assistant Secretary D. I. Coomber, O.B.E. J. M. Ottaway (Chairman) L. S. Bark L. C. Ebdon A. G. Fogg Analytical Division Secretary Miss P. E. Hutchinson Editor, Analyst and Analytical Proceedings Assistant Editor Ms. D. Chevin Mrs. J. Brew, R. A. Young Publication of Analytical Proceedings is the responsibility of the Analytical Editorial Board: "P. M. Maitlis A. C. Moffat B. L. Sharp J. D. R. Thomas A l l editorial matter should b e addressed to The Editor, Analytical Proceedings, The Royal Society of Chemistry, Burlington House, London W1V OBN. Telephone 01-734 9864.Telex 268001. Analytical Proceedings (ISSN 0144-557X) is published monthly by The Royal Society of Chemistry, Burlington House, London W1V OBN, England. 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No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means, electronic, mechanical, photographic, recording, or otherwise, without the prior permission of the publishers P. C. Weston Senior Assistant Editors Analytical Division Officers: Hon. Treasurer D. C. M. Squirrel1 President P. G. W. Cobb Hon. Publicity and Public Relations Officer Dr. J. F. Tyson, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire LE11 3TU A. M . Ure "P. C. Weston "Ex officio members Annual Reports on Analytical Atomic Spectroscopy Vol.12 Edited by M. S. Cresser and L. Ebdon This volume reports on current developments in all branches of analytical atomic emission, absorption and fluorescence spectroscopy with reference to papers published and lectures presented during 1982. Much of the information is in tabular form for ease of reference. 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Alphabetical Index; Appendix 1 : Late Entries to Classified Index; Appendix 2: Items too late for Classified; and Alphabetical Indices; Addresses of Distributors Softcover 480pp 0 85186 499 6 Price f 19.00 ($34.00) RSC Members f 12.50 ORDERING: RSC Members should send their orders to: The Royal Society of Chemistry, Membership Officer, 30 Russell Square, London WClB 5DT. Non-RSC Members should send their orders to: The Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 1HN. The Royal Society of Chemistry Burlington House London W I V OBN

ISSN:0144-557X    

DOI:10.1039/AP98522FX001

出版商:RSC    

年代:1985

数据来源: RSC

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ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 3 Research and Development Topics in Analytical Chemistry The following are summaries of sixteen of the papers and posters presented at a Meeting of the Analytical Division held on June 26th and 27th, 1984, in the University of Manchester Institute of Science and Technology. Some Aspects of the Pyrolysis Gas Chromatography of Quaternary Phosphonium Compounds Sarah J. Abraham and W. J. Criddle Department of Applied Chemistry, Redwood Building, UWIST, P.O. Box 13, Cardiff, CFI 3XF It is well accepted that quaternary ammonium halides of the general type R4N+X- decompose thermally to yield an amine, R3N, and the corresponding alkyl halide, RX.1-3 Early studies by Collie4-5 and others suggested that the thermal decomposition of quaternary phosphonium com- pounds follows a different path, forming a tertiary phosphine and an alkene when the anion is a halide: Et,P+Cl- + C2H4 + PEt3.HCI 2Me4P+Cl- + C2H4 + 2PMe3.HCl Ingold and co-workers later revised this6 to the expected tertiary phosphine and alkyl halide for phosphonium halides.The success of pyrolysis gas chromatography as an analytical tool for the determination of quaternary ammonium com- pounds7-9 suggested that the method would also be applicable to quaternary phosphonium compounds. In this paper we report the results of studies undertaken on the fundamental aspects of the pyrolysis of some simple phosphonium halides. Experimental The compounds studied were simple, readily obtainable or easily synthesised quaternary phosphonium halides.The cations used were (C2H5)4P+, (CH3)3P+Ph, (CH3)2P+Ph2, al C 0 P v) 2? P 8 a L a 1 Time Fig. 1. Pyrolysis of trimethylphenylphosphonium iodide by direct injection in aqueous solution. Injection port temperature, 350 "C CH3P+Ph3 and Ph4P+, while the anions used were chloride, bromide or iodide, these being easily interchangeable using ion exchange procedures. The pyrolysis procedures employed were direct injection (aqueous solution, 10-3 M) and the quartz tubekoil pyroprobe (CDS 190). Gas-chromatographic separations were carried out by using a Perkin-Elmer Sigma 2B gas chromatograph and data correlated on a Sigma 15 data station. The internal standards used were anilinium chloride and 4-toluidine oxalate. For sample preparation in oxygen-free atmospheres, a glove box flushed with white spot nitrogen was employed.Results and Discussion It will be immediately obvious from Table 1 that the pyrolysis of quaternary phosphonium compounds is considerably more complex than the corresponding nitrogen-based compounds. In addition, unless rigorous experimental conditions are adhered to, artifact formation can result. For example, in initial experiments using both the direct injection and pyro- probe techniques, the appropriate phosphine oxides were commonly formed, this effect being more serious for the chloride than for the iodides. Table 1. Products from the pyrolysis of typical quaternary phosphonium compounds Compound Products first X = halide observed at/"C Ph4PX Ph3P PhX PhPh PhH 225 MePh3PX MePh2P Ph,P Ph,PO MeX PhX 250 Observed products at 600 "C (probe) PhCH3 PhPh PhH + unknown Me2Ph2PX Me2PhP MePh2P MePh2P0 MeX 300 PhX PhH PhCH3 PhPh Me,PhPX Me,PhP Me2PhP0 Me3P MeX PhX 350 PhH PhPh PhCH3 However, oxygen from external sources, i.e., dissolved oxygen in the instance of direct injection pyrolysis, contributes to this effect.For pyroprobe pyrolyses, it Seems probable that the equilibrium can account for the appearance of phosphine oxides. This may be explained on the basis that the compound RX, if volatile, is partially lost during the sample work-up, and the free phosphine combines with atmospheric oxygen to give the R4P+X- C R3P + RX4 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 a, !z 0 II v) F E 8 L a, n Time 0 (D, i Time C) r- x ? Time Fig. 2. Pyrolysis of trimethylphenylphosphonium iodide aqueous solutions de-aerated with nitrogen.( a ) , Flame ionisation detector; ( b ) . nitrogen - phosphorus detector in the nitrogen - phosphorus mode; (c), nitrogen - phosphorus detector in the phosphorus mode. Internal standard, anilinium chloride (aniline retention time -7.7 min) . corresponding oxide. Support for this explanation may be found in that the chloride of, say, the trimethylphenylphos- phonium salt, gave rise to more oxide than the corresponding iodide. This is as expected because methyl chloride (a gas at room temperature) will be readily lost during sample prepara- tion. Preparation of all samples under nitrogen eliminates the formation of phosphine oxides for all of the halides examined. It should also be noted that, with pyroprobe pyrolyses, it is essential to allow all of the air that enters during sample insertion to be eliminated by carrier gas purging for some minutes before firing.If pyrolysis is initiated immediately on equilibration (or even by direct injection of a non-deaerated solution), extremely complex and essentially valueless chro- matograms are obtained (Figs. 1 and 2). Turning now to the nature of the genuine pyrolysis products, those indicated in Table 1 suggest that, in part at least, a free radical process is involved. There is no reason to suppose that in the pyrolysis of quaternary phosphonium halides, the electron transfer - free radical mechanism proposed initially by Criddle and Thomas") for the analogous nitrogen compounds does not hold, e.g., Ph,P+X- [Ph4P] + X- Ph3P + Ph t 2Ph + PhPh biphenyl Ph + X+ PhX halobenzene see Table 1 Ph + H+ PhH benzene In conclusion, it would seem that, from an analytical standpoint, pyrolysis gas chromatography is considerably more difficult to use as a general procedure than for the correspond- ing nitrogen compounds, but in carefully selected instances could be a valuable method for both the qualitative and quantitative determination of quaternary phosphonium com- pounds.1. 2. 3. 4. 5 . 6. 7. 8. 9. 10. References Hoffman, A. W., Justus Liebig Ann. Chem.. 1851, 78. 253. von Meyer. E . , Chem. Zentralbl.. 1909, 1800. Emde, H., Arch. Pharm., 1910. 247, 351. Collie, N., Philos. Mag.. 1887, 24, 27. Collie, N., J . Chem. Soc., 1888, 713. Fenton. G. F.. Hey, L., and Ingold, C. K., J .Chem. Soc., 1933, 989. Martens, M. A., and Heydrickx, A . , J . Pharm. Belg., 1974,29, 449. Choi, P., Criddle, W. J . , and Thomas, J . , Analyst, 1979, 104, 451. Christofides, A . , and Criddle, W. J . , J . Anal. Appl. Pyrol.. 1982,4, 211. Criddle, W. J . , and Thomas. J . , J . Anal. Appl. Pyrol., 1980,2, 361. Metals as Labels in lmmunoassay Nichola J. Wilmott, James N. Miller and Julian F. Tyson Chemistry Department, University of Technology, Loughborough, Leicestershire, LEI 1 3TU During the last decade a considerable research effort has been directed towards the development of non-isotopic labels for immunoassay; in principle, metals should make good labels. Suitably chosen metals should fulfil the requirements for a non-isotopic label, i. e . , non-toxicity, low cost, ease of introduc- tion into sample molecules, an absence or low level in serum and a low limit of detection.Two distinct approaches have been made in the development of this type of immunoassay and these fall under the headings Metalloimmunoassay (MIA) and Sol-particle immunoassay (SPIA) . Metalloimmunoassay The idea of metalloimmunoassay was first introduced by Cais,' who proposed the use of metal ions in the form of an organometallic or co-ordination complex as the label. The work carried out by Cais et al. in this area has included the labelling of steroids with sandwich compounds, such as ferrocene1.2 and complexes containing cymatrene,3 as well as direct introduction into the antigen molecule in the instance of mercuration of steroid oestrogens.4 Generally these labels have been found to be relatively insensitive in immunoassay terms, no doubt partly because the metals used (iron, manganese, etc.) occur at high concentrations in biological samples.Sol-particle Immunoassay This approach to the use of metals as labels was introduced by Leuvering et al.5 and involves labelling with colloidal particles. Leuvering et ul. developed a method for the determination of human chorionic gonadotropin (HCG) by colloidal gold labelling and a simultaneous assay for HCG and human placental lactogen by labelling with colloidal gold and colloidal silver. Analysis of the components was carried out by using carbon furnace electrothermal atomisation atomic-absorption spectrometry and, in general, the detection limits compared favourably with radioimmunoassay procedures.Experimental Terbium - Transferrin Complex as a Label in Immunoassay The approach used in our laboratory to the development of an MIA procedure was to produce a fluorescent chelate complex of terbium with transferrin as the label. The complex was produced in 0.1 M Tris - hydrochloric acid buffer at pH 8.5 by addition of terbium to a solution of transferrin in the molar ratio 2 : 1 .6 The complex had an excitation maximum at 294 nm, an emission maximum at 548nm and was detectable down to lo-' M (measurements were made on a Perkin-Elmer LS5 spectrometer: slits 5.0 and 5.0, delay gate 0.05ms, gate time 5.0 ms).ANALYTICAL PROCEEDINGS. JANUARY 1985. VOL 22 5 Gentamicin (an aminoglycosidic antibiotic) was linked to the complex via a carbodiimide reaction, an addition of glycine being made to limit the number of gentamicin molecules bound to each transferrin m ~ l e c u l e .~ The subsequent terbium - transferrin - glycine - gentamicin complex was then tested for reaction with anti-gentamicin antibody: a double antibody technique was used whereby the gentamicin-containing com- plex was reacted with anti-gentamicin and subsequently with antibody to the anti-gentamicin to cause precipitation. The antibody titration results showed typical antigen - antibody reaction between the anti-gentamicin and the gentamicin complex. Attempts to use the gentamicin complex in an immunoassay procedure have so far proved relatively unsuccessful, no doubt partially due to the problems associated with kinetics and a macromolecular label.It is also possible that scattered light is affecting the fluorescence measurements, and at present experiments are being carried out on diluted solutions. We also intend to carry out the terbium determination by plasma emission spectrometry. Colloidal Gold as a Label in Immunoassay Colloidal gold was prepared by the reduction of chloroauric acid by sodium citrate, according to the method of Frens.8 Colloidal particles of average particle diameter 20 nm were used in the experiments. The adsorption of colloidal gold on to albumin (dialysed in order to remove electrolytes) was carried out by simple adsorption ~ aggregation of the labelled albumin being preven- ted by the addition of polyethylene glycol ( M , 20000).The exact amount of albumin required to stabilise the colloidal gold was determined by the construction of an adsorption isotherm4; varying concentrations of albumin (contained in 1 ml of water) were added to 5 ml of colloidal gold and allowed to stand for 1 min, 1 ml of 10% NaCl then being added and, after a period of 5 min. the degree of flocculation measured by the absorbance of the solution at 580 nm (the absorbance of the solution increasing for flocculated colloids which appear blue). The optimum pH of the colloidal solution was determined in a similar manner by using a concentration of albumin known to stabilise the colloidal gold. Having determined the optimum conditions for the prepara- tion of colloidal gold labelled albumin the labelled colloidal gold was used in an antibody titration.The double antibody technique was again used and results obtained showed good antibody recognition. All of the analyses carried out to date have involved spectrophotometric analysis. However, analysis of the labelled albumin by carbon furnace atomic-absorption spectrometry with electrothermal atomisation has been carried out and suggests that extremely small amounts can be detected by this means. Conclusion Generally, the methods of MIA have been found to be less sensitive than those of SPIA, mainly due to the number of metal ions bound per molecule, i . e . , one or a number less than 10 in the case of MIA compared with the many thousands per colloid particle. However, the number of possible complexes available for MIA is vast and does open up a number of areas and subsequently several different detection methods.But perhaps the most interesting factor concerning SPIA is the possibility of multi-component analysis which, with the use of such methods as plasma emission spectrometry and neutron activation analysis, may lead to simultaneous assays for two or more components. The authors thank the Trustees of the Analytical Trust Fund of the Royal Society of Chemistry for the award of an SAC Research S tuden tship. References 1. 2. 3. 4. 5. 6. 7. 8. 9. Cais, M., Nature (London), 1977, 270, 534. Cais, M., U.S. Pat., 4 205 952, 1980. Cais, M.. Bull. SOC. Chim. Belg., 1981, 90, 27. Cais, M., Actual. Chim., 1979 (7), 14. Leuvering, J. H. W., Thal, P. J . H. M., Van der Waart, M., and Schuurs.A. H. W. M., J . Zmmunoassay, 1980, 1, 77. Luk, C. K., Biochemistry, 1971, 10, 214. Wilmott. N. J . , Miller, J . N., and Tyson, J. F., Analyst, 1984, 109, 343. Frens, G., Nature (London), Phys. Sci., 1973, 241, 20. Geoghegan, W. D., and Ackerman, G. A , , J. Histochem. Cytochem., 1977, 25, 1187. The Simultaneous Determination of Chloride, Bromide and Iodide by HPLC Philip E. Moss and W. 1. Stephen Department of Chemistry, University of Birmingham, P. 0. Box 363, Birmingham, B 15 2TT A new technique is proposed for the simultaneous determi- nation of chloride, bromide and iodide in aqueous solution. The method depends on the ease with which an inorganic halide ion can be quantitatively converted to a covalently bound arylmercury(I1) halide, which is then measured by high-performance liquid chromatography (HPLC).Several methods are available for this conversion. e.g., the Peters' reaction,' a Grignard-type synthesis2 and an aryl- boronic acid technique.3 The last technique was adopted because it proceeds rapidly almost to completion at room temperature. Experimental Preparations of Phenylmercury(I1) Halides Phenylmercury( 11) chloride, bromide and iodide were pre- pared by addition of the corresponding alkali metal halide (potassium bromide, etc.) to a solution containing phenylboric acid (benzeneboronic acid) and a mercury(I1) salt (nitrate or perchlorate) made acidic to about pH 1.0 with the correspond- ing acid. The phenylmercury( 11) halide produced was extrac- ted into chloroform, the chloroform removed by evaporation and the compound purified by recrystallisation from ethanol.A series of substituted phenylmercury(I1) halides was produced by the same technique using substituted phenylboric acids. Those so far studied are 4-bromophenylboric acid (4-bromobenzeneboronic acid), 2,4-dichlorophenylboric acid (2,4-dichlorobenzeneboronic acid) and 3,5-bis(trifluoro- methy1)phenylboric acid [3,5-bis(trifluoromethyl)benzene- boronic acid]. Measurement of Phenylmercury(I1) Halides The phenylmercury(I1) halides (substituted and unsubstituted) were dissolved in a suitable solvent (ethanol or ether) and measured by HPLC under conditions of isocratic elution. The system used consisted of two 5 p ~ ODS columns linked together to provide a 35 cm long active column (4.6 mm i.d.). The injected volumes were of 5 1.11.Detection was by ultraviolet absorption at 220 nm [230 nm for 4-bromophenylmercury(II)6 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 halides]; peak height and/or peak area measurements were used. Interferences Both cationic and anionic interferences were studied at ten-fold concentrations compared with the respective halide. Results Phenylboric Acid Technique The three phenylmercury(I1) halides were prepared and isolated as described above. Preliminary tests showed that phenyImercury(I1) chloride, bromide and iodide were best separated with a methanol - water (4 : 1) eluent at a flow-rate of 1 ml min-1, the order of elution being from chloride to iodide. When 1,2-dichloroethane was used, the extraction was quantitative for all three halides over the concentration range 0-100pgml-1.Recoveries of about 100% of the added amounts were possible for chloride and bromide, but only 70% for iodide. Substituted Phenylmercury(I1) Halides Several substituted derivatives were prepared as outlined above and examined under the same conditions as those used for the unsubstituted compounds. The chromatographic behaviour of these compounds differed markedly from the unsubstituted phenylmercury(I1) halides (see Discussion, below). 4-Bromophenylboric Acid Technique When the three 4-bromophenylmercury( 11) halides obtained from the 4-bromophenylboric acid were analysed under identical conditions to the unsubstituted compounds much better separations were obtained compared with the unsubsti- tuted compounds.When dichloromethane was used, the extraction of the 4-bromophenylmercury( 11) halides was quantitative over the range 0-100 pg ml-1 halide concentration with recoveries of about 100%. Discussion Phenylboric Acid Technique This can be used for the simultaneous determination of chloride, bromide and iodide but it has several drawbacks. The need to use dichloroethane as solvent leads to loss recoveries of iodide, possibly because of the lower solubility of phenylmer- cury(I1) iodide in dichloroethane. The relatively low A,,,. values (around 220 nm) for the phenylmercury( 11) halides lower the sensitivity and give higher noise than might be hoped for. The major drawback, however, is that phenylmercury(I1) chloride requires conditioning on the column prior to use, about 20 injections being sufficient to reach conditions of reproducible retention times and sensitivities.This may be caused by the adsorption of the phenylmercury(I1) chloride on to the silica column packing, it being the most polar of the three compounds. The problem can also be overcome by the addition of a small amount (about 1 pg ml-1) of the phenylmercury(I1) chloride to the eluting solvent. Substituted Phenylmercury(I1) Halides The substituted phenylmercury(I1) halides show a definite pattern in their chromatographic behaviour. The chlorides seem to be relatively unaffected by substitution and still elute first from the column. The bromides and iodides, however, show increasing retention times (and resolutions) as the electron-withdrawing power of the substituent increases, the order being (from least effective to most effective) 4-bromo- phenylmercury halides, 3,5-bis(trifuloromethyl)phenyl- mercury halides and 2,4-dichlorophenylmercury halides.The position of substitution also appears to be important, with the 2- and 4-positions having the greatest effect. A secondary effect is that as the electron withdrawing power increases the amounts of the corresponding substituted diphenylmercury by-products also increases. With the 33- bis(trifluoromethy1) substituents, the corresponding iodide has yet to be produced, probably because of the increased electron-withdrawing power weakening the already fairly weak mercury iodide bond. Because of this problem, the 4-bromo compounds were chosen for study. They also have a further advantage in giving a second absorption maximum at 230 nm.4-Bromophenylboric Acid Technique Although the conditioning problem also occurs with the 4-bromophenylmercury( 11) chloride compound, it can be overcome in the same way as for the unsubstituted chloride and under optimised conditions of eluent flow (1.2 ml min-1) it is a routine matter to determine simultaneously chloride, bromide and iodide in an aqueous solution with recoveries of about 100%. Interferences There are few interferences in this method. Cations that form sparingly soluble salts with halide ions ( e . g . , Ag+, Hg22+, Pb2+, etc.) interfere but at concentrations below the relevant solubility product the effect is small. Anionic interferences are cyanide and thiocyanate, which form the corresponding arylmercury compound, but acetate, phosphate, nitrate and perchlorate do not interfere. Further Studies An examination of the behaviour of the corresponding tolylmercury(I1) halides prepared from the three tolylboric acids (tolueneboronic acids) may provide interesting informa- tion on the chromatographic separation, which may lead to some improvement to the present technique.The possibility also exists for a modified version of the method to be used for the determination of low concentrations of mercury( 11) ions in aqueous media. References 1. Peters, W . , Ber. Dtsch. Chem. Ges., 1905, 38(3), 2565. 2. TsuTsui, M., “Characterisation of Organometallic Com- pounds,” Part 11, Wiley-Interscience, New York, 1971, p. 696. 3. Yazdi, A . S . , Ph.D. Thesis, University of Birmingham, 1982.Applications of Immobilized Enzymes in Flow Injection Analysis M. Masoom and Alan Townshend Chemistry Department, University of Hull, Hull, HU6 7RX Immobilized enzymes have received much attention in the past decade.’ They have a number of advantages over soluble enzymes when used in analytical systems, including decreased cost, greater stability and greater convenience of use. Their application is growing rapidly in clinical analysis, food analysis and for process control. The use of flow systems in conjunction with immobilized enzymes has been particularly effective. In this study flow injection analysis (FIA) is combined with immobilized enzyme technology and a flow-through ampero- metric detector. The cell consists of two parallel, platinumANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 Phosphate buffer pH 6.8 7 1 *W - lnvertase electrodes, with a potential difference of 0.6 V, which detects hydrogen peroxide down to 1 x 1 0 - 6 ~ .The system first studied was the determination of glucose, by using glucose oxidase (GOD): Glucose + 02- Gluconic acid + H202 GOD was immobilized on controlled porosity glass (CPG) by cross-linking with glutaraldehyde: OEt OEt I I I 1 CPG -OH + EtO-Si-(CH2)3NH2 -.+ CPG-O--Si-(CH2)3NH2 OEt (A) OEt OEt H I I I (A) + OHC-(CH2)3-CH0 + CPG-0-5 -tCH2),-N=C(CH2)3-CH0 (B) OEt OEt H 1 I I (B) + H2N-Enz -* CPG -O-Si-(CH213-N=C-(CH2)3-CH=N-Enz OEt The immobilized enzyme was packed into a glass column (25 X 2.5mm) with an outer, thermostatted water jacket. Blood sera were analysed for glucose at a rate of 300 samples h-I simply by injecting them into a pH 7 phosphate buffer stream and passing them through the enzyme column.Fig. 1 shows typical recorder outputs for glucose calibration and two control blood sera. The results for the sera agreed well with the expected values. The manifold is so simple that it can easily be 5 rnin H 20 20 Fig. 1. Typical recorder output for standard glucose solutions followed by two control sera and standard glucose solutions automated and would be extremely suitable in a dinical laboratory for routine or emergency use, or both. Sucrose has been determined in a similar way, by incorpora- tion of an immobilized invertase - CPG column, prior to the GOD column: Sucrose D-Fructose + a-D-Glucose The glucose produced is then determined after passage through the GOD column, as before.The substrate for GOD, however, is P-D-glucose, therefore mutarotase is needed for the conversion of a- to 6-D-glucose. Various methods for the immobilization of mutarotase all gave unstable preparations, but immobilization of invertase and mutarotase together on CPG gave a stable product. The immobilization reactions were as shown in scheme 1. Fig. 2 shows the simple manifold used for sucrose determin- ation. Determination of Sucrose and Glucose In many food production processes, combinations of sugars, especially glucose and sucrose, are important, making their parallel measurement necessary for effective process control. Various enzyme electrodes2.3 have been suggested for this purpose, but such methods suffer from the disadvantages of poor reproducibility and long response and recovery times.The present system has been applied to the analysis of mixtures of sucrose and glucose. As shown in Fig. 2, a by-pass around the invertase column controlled by two 2-way keys enables the flow to pass either through both columns (for determination of sucrose and glucose) or through the GOD column (for determination of glucose only). The two sugars were determined within 35 s, both in standard mixtures (Table 1) and in soft drinks, by two sequential sample injections. The method is simple, fast, and reliable. a l n l n - z z $ s F CI L a - - al r: lu z u Time + Fig. 3. Typical output for the simultaneous determination of sucrose and glucose in a soft drink The system can be refined to determine sucrose and glucose in a single sample injection by splitting the sample so that it simultaneously flows through the invertase and GOD columns, and just the GOD column (Fig.2). The portion of sample not passing through the invertase column is delayed so that it reaches the GOD column after the other portion. Thus, two8 ANALYTICAL PROCEEDINGS. JANUARY 1985, VOL 22 OEt H O OEt H O H I I I NH2 + OHC- (cH2)3- CHO + CPG- 0 -Si -(CH2)3-N-C I CPG-O-Si-(CH2)3 -N-C b E t OEt (A) OEt H H I N=C-(CH2)3-CH =N-Enz I I (A) + H2N-Enz -+ CPG-0 -Si-(CHp),-N-C OEt Scheme 1. from sucrose and glucose, the second from glucose only, as can Such systems are currently being applied to many other Table 1. Analysis Of mixtures Of sucrose and glucose.Glucose, be Seen from Fig. 3. Again, fast, accurate results are obtained, 0.5 mM; signal, 0.433 PA. Current peak height given in FA Sucrose/ Combined Glucose Sucrose Pure sucrose oxidases* mM signal signal in mixture signal 1 .0 0.887 0.443 0.443 0.420 References 2.0 0.980 0.420 0.560 0.560 1. Carr, P. W., and Bowers, L. D., “Immobilized Enzymes in 3.0 1.260 0.420 0.841 0.794 Analytical and Clinical Chemistry,” John Wiley, New York, 4.0 1.401 0.420 0.981 0.981 1980. 5 .0 1.587 0.420 1.168 1.121 2. Pfeiffer, D., Scheller, F., Janchen, M.. and Bertermann. K.. Biochimie, 1980. 62, 587. Scheller, F., and Renneberg. R., Anal. Chirn. Acra, 1983, 152. 265. 3. signals are obtained in succession from the detector, the first Studies of Tin Oxide Semiconductors as Novel Gas-chromatographic Detectors S.J. Rowley, L. Ebdon and M. M. Rhead Department of Environmental Sciences, Plymouth Polytechnic, Drake Circus, Plymouth, PL4 8AA and D. A. Leathard Department of Chemistry, Sheffield City Polytechnic, Pond Street, Sheffield, S 7 7 WB The effect of gases upon the conductivity of certain semicon- ductors was first noted in the early 1950s.’ This phenomenon has since been developed in the manufacture of sensors in gas alarm systems.2 Although a certain selectivity to different gases can be induced by controlling the composition of the sensor during manufacture, or varying the operating conditions, this is insufficient to be of any real analytical value. However, combination of the high sensitivity of semiconductor sensors with the selectivity of gas chromatography (GC) can provide a practical analytical technique with many applications.There are several semiconducting materials which react with gases; the most popular are the oxides of zinc and tin, because of their sensitivity, and certain organic semiconductors for their selectivity. This paper is concerned only with tin(1V) oxide (SnO,) devices. Instrumentation There are several commercially available sensors designed for environmental monitoring and alarm systems. Some of these are readily convertible to GC detectors. A typical device is shown in Fig. 1. The wires connecting the electrodes and heater to their relevant circuits also serve as supports suspending the bead from pins set into a ceramic base. As a GC detector the device must be positioned in the post-column gas stream.To accomplish this a housing consist- ing of a rectangular block has been fabricated in stainless steel. A longitudinal hole is drilled through the housing and tapped at its ends to take the coupling that will connect it to the chromatographic column. A hole is drilked into the side of the block, enabling the sensor to be inserted in such a way that the bead protrudes into the gas flow. All fittings are gas tight. In order to complete the instrumentation a stable power supply is required for the integral sensor heater and precise amplification coupled with an ordinary chart recorder or integrator for data output. The column, oven, carrier gas control and sample injection port are conventional. Although no fuel gas is required, as with the flame ionisation detector (FID), the semiconductor detector does need a supply of oxygen.The device can actually be run in an oxygen-free atmosphere, in fact the response may be enhanced in this mode, but the sensor will eventually be reduced and degrade. There is probably an optimum level of oxygen for maximum response and sensor life, but as the sensors were originally designed to run in air, this provides a cheap and convenient carrier gas. Unfortunately, air limits column packings to those which are not damaged by oxidation, mainly solid absorbents It is, however, possible to use other types of packings, and an inert carrier gas, by the addition of oxygen as a post-column make up, either continuously or between runs. e H ntered tin oxide Alumina t u b e Fig.1. Diagram showing the structure of a typical Figaro gas sensorANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 9 Operation Semiconductor detectors are temperature dependent, there- fore all variables affecting the surface temperature of the device must be controlled and optimised. There are four such variables, sensor heater voltage, detector flow, carrier gas flow and column temperature. Sensor heater voltage (V,) has the most effect upon the surface temperature and thus determines the over-all sensitiv- ity and selectivity to particular compounds. The surface temperature is proportional to VH as is, generally, the sensitivity. For example, when VH = 3 V the TGS 813 detector exhibits equal sensitivity to methane and propane, at V , = 4 V response to propane is greater than to methane, and at VH = 6 V this order is revzrsed. Hence, it is possible to tune the system to a certain extent according to the application.The other three variables affect the sensor temperature by thermal mass transport. Generally a hotter gas at a low flow-rate will result in a higher surface temperature, and consequently response, than a cool gas at .a high flow-rate. Column temperature and carrier gas flow are also the major variables controlling the chromatographic separation and peak shape. Detector flow can be controlled by the provision of a controlled split, or make up, between the column and the detector. All four variables are interdependent in their effect upon the sensor operation. Optimisation has been achieved by using the variable step size simplex technique.3 Peak height response was chosen as the criterion of merit, rejecting vertices not giving adequate component separation.4 4 2 co -1 Fig.2. Chromatogram showing exhaust gas analysis. Conditions: activated charcoal 2 m x 4 mm at 97 “C; carrier gas, air at 100 ml min l . Sensor, TGS 815, VII = 6 V Fig. 3. Chromatogram showing separation of hydrogen sulphide and methane. Conditions: 2 m x 4mm, activated alumina at 170°C. Carrier gas, air at 40ml min-I. Sensor. TGS 816, VIT = 6 V Applications Figs. 2, 3 and 4 are chromatograms demonstrating some of the features and advantages of semiconductor detectors. The first shows the analysis of petrol engine exhaust gases, providing useful information for both tuning and pollution control.The ability to analyse these three compounds, hydrogen, carbon monoxide and methane, on one column and with a single detector in one run, illustrates one of the main advantages- versatility. The detection limit for hydrogen of 40 p.p.b. clearly demonstrates the second advantage, namely sensitivity. Fig. 4. Chromatogram showing separation of nitrogen and argon. Conditions: 2 m x 4mm, molecular sieve 5A at 90°C; carrier gas, oxygen at 30mlmin-1. Sensor, TGS 813, VH = 6.23 V This particular separation was popular in early applications of the semiconductor detector, e . g . , determination of these compounds as components of “firedamp” in mine air analy~is,~ and analysis of these gases in fjord sediments. The robust nature of the device and the low cost of the carrier gas make it ideal for portable instrumentation.The second chromatogram (Fig. 3) shows the separation of hydrogen sulphide and methane, demonstrating resistance to poisoning, an advantage of this detector over other solid-state devices (i. e. , catalytic bead). The sensor manufacturer claims sensitivity to a wide variety of organic and inorganic compounds.6 The range of organic compounds includes alkanes, alkenes, alcohols, ketones, amines, acetates and freons. The semiconductor detector obviously has the potential to replace the FID in many applications. The following gases can also be detected: hydrogen, carbon monoxide, carbon dioxide, sulphur dioxide, hydrogen sulphide and ammonia. Fig. 4 shows the analysis of a mixture of argon and nitrogen.Sensitivity to these compounds is very low compared with the reducing gases, but indicates a possible thermal conductivity mechanism of response in addition to, but at a lower level than, the accepted reduction - valence bond promotion mechanism. The sensor response to other gases is known to be complex and current theories7 consider it likely that four or more mechanisms are involved simultaneously. Conclusions The semiconductor detector for GC is a versatile, sensitive, safe and robust device. It is a relatively low cost item with low running costs. In many applications it can replace the FID or thermal conductivity detector (TCD) and multi-detector arrangements. The robust nature of the detector and its non-reliance on bottled gas, when operated with an air compressor, make the device suitable for field operation.There are many applications in the industrial, mining, environ-10 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 mental and medical fields as a portable or ambulatory 3. instrument.8 4. In the laboratory the potential of semiconductor detectors in gas analysis and replacement of multidetector systems are 5 * diverse and numerous. References 6. Brattain, W. H., and Bardeen, J., Bell Syst. Tech. J . , 1953,32, 7. 1. 8. Watson, J. , and Tanner, D., Radio Electron. Eng., 1974,44,85. 1. 2. Nelder, J. A., and Mead, R., Comput. J., 1965, 7 , 308. Ebdon, L., Ward, R. W., and Leathard, D. A., Analyst, 1982, 107, 129. Leathard, D. A., Wynne, A., and Ebdon, L., RSC Interna- tional Conference on “The Detection and Measurement of Hazardous Substances in the Atmosphere,” City University, London, 1982.Manufacturers literature, Figaro Engineering, Japan. Morrison, S. R., Sensors Actuators, 1982, 2, 329. Christman, N. T., and Hamilton, L. H., J. Chromatogr., Biomed. Appl., 1982, 229,259. The Effect of Materials of Clinical Interest on Calcium lon-selective Electrode Response Sajedah A. H. Khatil, G. J. Moody, G. de Oliveira Net0 and J. D. R. Thomas Applied Chemistry Department, Redwood Building, UWlST, P.O. Box 13, Cardiff, CF1 3XF The use of potentiometry in clinical chemistry has been widened by advances in ion-selective electrode technology. For calcium the recent advances in electrode design’ have greatly improved the scope of such measurements. However, the accurate use of calcium ion-selective electrodes is affected by proteins.2 Also, marry studies have been directed to determin- ing the clinical circumstances in which direct potentiometry with ion-selective electrodes gives different values and also determining which conditions lead to more accurate values for clinical use.3 The purpose of the present work has been the study of interferences by biochemical type materials on calcium ion- selective electrodes based on calcium bis{di-[4-( 1,1,3,3- tetramethylbutyl)phenyl]phosphate} in conjunction with each of dioctylphenylphosphonate (DOPP) (electrode I), tripentyl phosphate (TPP) (electrode 11) and trioctyl phosphate (TOP) (electrode 111) as plasticising solvent mediator.Experiments have also been carried out on electrodes made from mem- branes obtained from a commercial supplier (electrode IV).This study is merited since, on the whole, there has been little study of interference effects of materials of biochemicaI interest on calcium ion-selective electrodes to match those of the rather unusual interference on calcium ion-selective electrodes by anionic surfactants.4.5 Experimental Poly(viny1 chloride) (PVC) matrix membrane electrodes with inner solutions of 10-1 M calcium chloride were assembled by previously described procedures637 and calibrated against a saturated calomel reference electrode with serially diluted calcium chloride solutions (10-1-10-5 M range) in water or 0.15 M sodium chloride solution. The electrodes (I, 11, 111 and IV listed in the introduction) were tested for interference from various biochemical materials by adding 0.05-cm3 aliquots of a solution (5 x 10-2 M) of the interfering component under study to a calcium chloride containing solution (25 cm3).The calcium chloride solutions were of 10-2 or 10-3 M concentration, made up in either water or 0.15 M aqueous sodium chloride. E.m.f. readings were noted for each aliquot added until the background calcium chloride solution contained at least a 10-3 M concentration of interfer- ent. Because of their limited solubility in water, cholic acid, lecithin, cholesterol and vitamin D2 were dissolved in ethanol and propan-1-01, although cholesterol is only slightly soluble in ethanol. The effect of alcohol alone on each electrode was also studied. Table 1. E.m.f.changes for cells with calcium ISEs corresponding to various components added to test solutions containing calcium AE caused by added components to solutionslmv Component of Concentration 10-3 M or 0.5 cm3 alcohol added to 25 cm3 solution SDS DBSS Cholic acid (in propanol) Cholic acid (in ethanol) Cholesterol (in propanol) Cholesterol (in ethanol) Lecithin (in proganol) Lecithin (in ethanol) Vitamin D2 (in propanol) Vitamin D2 (in ethanol) Urea Glucose Imidazole Ethanol Propan-1-01 (I) Dioctylphenylphosphonate (11) Tripentylphosphate (111) Trioctylphosphate (IV) Philips membrane electrodes (DOPP) electrodes (TPP) electrodes (TOP) electrodes 1 , CaCl, in CaCl, in CaCl, in CaCl, in CaC12 in CaC12 in CaC12 in CaC12 in water 0.15 M NaCl water 0.15 M NaCl water 0.15 M NaCl water 0.15 M NaCl -------- 10-2 M 10-3 M 10-2 M 10-3 M 10-2 M 10-3 M 10-2 M 10-3 M 10-2 M 10-3 M 10-2 M 10-3 M 10-2 M 10-3 M 10- 2 M 10-3 M -55.0 -65.8 -85.0 -85.7 -63.0 -32.0 -40.0 -15.0 -9.1 -3.3 -12.5 -9.7 -35.9 -17.0 -41.5 -24.0 -10.4 -6.7 -24.3 -8.8 -26.0 -16.9 -10.0 -12.7 -17.1 -16.3 -13.1 -17.4 -9.6 -11.6 -6.8 -11.3 -3.0 -11.2 -3.1 -2.3 -21.0 -8.8 -12.6 -10.1 -3.1 -5.1 +4.1 +2.5 -2.8 -3.2 -0.6 -3.5 -8.6 -3.7 -6.4 -6.4 -10.0 -9.2 -7.3 -10.9 -2.4 -13.7 -5.6 -6.5 -5.4 -5.3 -10.5 -9.8 -3.5 -8.5 -5.3 -5.3 -10.3 -6.2 -11.2 -10.9 -2.4 -3.8 -3.0 -2.8 -5.0 -3.5 -6.5 -7.0 0.0 +0.1 -0.9 +0.2 +0.3 -0.8 +0.8 -0.1 0.0 +0.2 -0‘2 -0.1 0.0 0.0 -1.1 +0.4 -1.0 +2.2 0.0 -5.0 -2.2 +1.0 +0.3 -1.0 -2.8 -2.7 -4.8 -3.8 -2.6 -3.8 -2.5 -3.5 -6.7 -13.0 -9.1 -8.2 -10.5 -15.6 -8.0 -10.2 -9.0 -2.0 -4.0 -0.8 -2.0 +1.1 -5.0 + 1.0 -4.1 +2.0 0.0 0.0 +1.2 +3.7 +3.4 - 17.3 -2.0 -0.42 -2.6 +1.6 +1.6 +0.4 +1.6 -5.6 -7.8 -0.1 -0.3 +0.6 +4.8 +5.1 -2.8 -7.2 -102 -3.8 -1.5 -55.9 -2.2 -2.8 -2.4 -0.6 +1.2 -7.1 +1.7 +0.2 -3.5 -0.2 +1.3 -1.0 +0.2 +0.2 -0.6 -0.2 -7.6 -3.6 -0.2 +0.2 -1.7 -0.3 -0.1 -4.5 -3.8 -1.3 -1.7 +2.1 +3.3 -0.3 +3.2 +2.2 -2.3 +0.5 +1.9 +0.3 +1.0 +2.8 +1.0 -73.5 -26.5 -25.1 -93.3 -39.8 -59.8 -0.5 -1.2 -1.6 +3.3 -1.6 +0.4 -1.7 -2.2 -0.3 -0.6 0.0 -1.8 -2.6 -2.2 +0.6 -4.0 -1.5 -3.1 +0.9 -0.1 -0.8 0.0 -0.5 -0.5 +1.2 +0.7 -1.1 +0.2 +0.5 +0.1 -2.0 -2.0 -3.0 +0.8 +0.4 +3.3 +2.0 +5.7 +1.7ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 11 Results and Discussion E.m.f.changes of less than 0.5mV were observed for up to 10-3 M of starch, sucrose, uric acid, creatinine and bilirubin for all four electrodes.Table 1 summarises the e.m.f. changes corresponding to the presence of added interferent up to a concentration of 1 0 - 3 ~ ~ or of 0.5cm3 of alcohol added to 25 cm3 of the background calcium chloride solution. As was reported earlier,5 and confirmed here, electrode compositions represented by electrode I11 with a calcium bis{ di-[4-( 1,1,3,3-tetramethylbutyl)phenyl]phosphate} sensor and trioctyl phosphate solvent mediator are much superior to other membrane systems in resisting interference by anionic surfactants, such as sodium dodecylsulphate (SDS) and dodecylbenzene sodium sulphonate (DBSS) (see Table 1). Similar efficacy i s also shown by electrode 111 in the data given in Table 1 for the biochemical interferents from among those electrodes based on the organophosphate sensor (electrodes I, I1 and 111).For the biochemical interferents, note must be taken of the effect of ethanol and propan-1-01 interference on electrode response (Table 1), which will be superimposed on the interferences of the biochemical solute. Propan-1-01 seriously affects electrodes I and 11, while the effect of added alcohol in other instances is less than 5 mV for 0.5 cm3 of added alcohol. Different from the effect shown by other electrodes, the e.m.f. of electrode I11 increases when alcohol is added, and this may be a contributory factor in the apparently small interferences shown by the biochemical components recorded in Table 1. The data for electrode 1V (Philips membrane) show this electrode to be as little affected by added biochemical components as that of electrode 111.This is contrary to the experience with electrode IV for anionic detergent surfactant (see Table 1 and reference 5). The nature of the observed interferences for biochemical materials may be due to calcium binding sites or to surfactant properties of at least some of the materials, e.g. , lecithin. More generally, lipoproteins that contain cholesterol and phospho- lipids are surface active agents, so that the kind of interferences noted here are of interest in relation to the role of calcium ion-selective electrodes and, indeed, ion-selective electrodes in general in the clinical field. Conclusion Similarly to the observations with anionic surfactants,S the replacement of trioctyl phosphate (electrode 111) for dioctyl- phenylphosphonate (electrode I) solvent mediator in the PVC calcium ion-selective electrode based on bis{di-[4-( 1,1,3,3- te trame t h y 1 buty1)phenyllphuspha te} sensor can reduce inter- ferences from components likely to occur in body fluids, but there must be regard to the effect of alcohol used for dissolving interferents.Electrodes made from commercial membranes (electrode IV) behave similarly to electrode I11 with respect to relative freedom from interference by the biochemical materials studied. However, before making firm recommenda- tions on the relative merits of these electrodes, further studies have to be made on the effect of inorganic ions, such as potassium, sodium, magnesium and zinc, on their responses.The authors thank the Foundation of Technical Institutes, Baghdad, Iraq, for paid leave of absence and a studentship (granted to S. A. H. K.) and the Conselho Nacional de Desenvolvimento Cientifica e Technologico, Brazil, and the British Council, London, for financial support (to G. de. 0. N.) References 1. 2. Moody, G. J . , and Thomas, J. D. R., Ion-Sel. Electrode Rev., 1979,1,3. Payne, R. B., “International Symposium on Electroanalysis in Biomedical, Environmental and Industrial Sciences, UWIST, Cardiff, 5-8 April 1983,” paper 13. Ladenson, J. H.,Anal. Proc., 1983,20,554. Craggs, A., Moody, G. J . , Thomas, J. D. R., and Birch, B. J., Analyst, 1980,105,426. Frend, A. J., Moody, G. J., Thomas, J. D. R., and Birch, B. J., Analyst, 1983,108,1072. Moody, G.J . , Oke, R. B . , andThomas, J. D. R.,Analysr, 1970, 95, 910. Craggs, A., Moody, G. J., andThomas, J. D. R., J . Chem. Educ., 1974,51,541. 3. 4. 5. 6. 7. Piezoelectric Quartz Crystal Detection of Ammonia Colin S. 1. Lai, G. J. Moody and J. D. R. Thomas Applied Chemistry Department, Redwood Building, UWIST, P.O. Box 13, Cardiff, CFI 3XF Coated piezoelectric crystal detectors have developed into a highly sensitive technique for the detection of traces of atmospheric pollutants, 1 The detection of a specific component is observed as a change in the resonant frequency of the crystal as a result of selective sorption by the coating. Sauerbrey2 derived an expression relating the mass of metal films deposited on quartz crystals to the change in frequency. For commercially available crystals the form of this equation is AF = -2.3 x 1OhFAm/A, where AFis the change in frequency (Hz), F i s the initial frequency of the quartz plate (MHz), Am is the mass sorbed (8) and A is the area of the coating (cm2).From this it can be predicted that a 9MHz crystal with an approximately 0.5 cm2 coating would have a mass sensitivity of up to about 400Hzpg-1 to yield a detection limit of about Application of the piezoelectric quartz crystal detection method is decribed here for ammonia, using pyroxidine (vitamin Bb) hydrochloride as the detecting coating material. 10-’2g. Ammonia Detection with Pyridoxine Hydrochloride The role of Antarox CO 880, a nonylphenoxypolyethoxylate with 30 ethoxylate units, as a support matrix for a pyridoxine (vitamin B6) hydrochloride coating on a piezoelectric crystal for detecting ammonia has previously been described.3 It was shown that the Antarox CO 880 was an effective agent for prolonging the useful life of the piezoelectric ammonia detector.3 Thus, the frequency change corresponding to 30p.p.m.of ammonia for a piezoelectric crystal coated with pyridoxine hydrochloride alone dropped from about 300 Hz on day 2 to less than 50 Hz on day 6, while the frequency change for a piezoelectric crystal coated with pyridoxine hydrochloride supported by Antarox CO 880 remained at about 200Hz for over 50 days for samples containing the same level of ammonia.3 A similar pattern has been observed in the present study, the sample size being 1 cm3 in each instance. For larger samples (5cm3) it is possible to follow the frequency changes for more dilute samples using the apparatus previously described3 with a 9 MHz resonant frequency AT cut quartz crystal with a gold electrode.Again, the Antarox CO 880 matrix permits a long useful life for the piezoelectric detector. Typical results are summarised in Table 1 for p.p.b. (pg dm-3) levels of ammonia, the blank values corresponding to background moisture.12 ANALYTICAL PROCEEDINGS. JANUARY 1985, VOL 22 Table 1. Frequency changes (AF) in hertz corresponding to responses to ammonia-containing samples of a piezoelectric quartz crystal coated with pyridoxine hydrochloride and Antarox CO 880. Slopes of log AF versi~s log[NH3] graphs range from 0.156 to 0.206 Ammonia gas, p.p.b Period/d Blank 463 56 6.7 0.80 0.0% 0.012 1 28 325 211 137 86 59 43 2 20 362 233 125 93 61 41 3 18 299 189 125 94 60 44 20 232 169 123 82 52 42 I q 5 8 24 252 274 113 83 51 - 10 24 211 152 121 79 56 -:I Interferences to Ammonia Detection Tnterferences from other gases in the assay of ammonia are listed in Table 2 for Antarox CO 880 - pyridoxine hydro- chloride coatings.Table 2. Frequency changes (AF) for various interfering gases and controls for piezoelectric crystal coatings of Antarox - pyridoxine hydrochloride A FtHz for 5 cm3 samples passed over crystal coatings Gas NH3 NH3 SO? HCI coz HZS NO? Room air Dried room air Triethylarnine Triet h ylarnine Gas concen- tration, p.p.m. 0.463 32 101 75 109 1480 116 - - 3.6 36.4 Pyridoxine hydro- Pyridoxine chloride hydro- on Antarox chloride CO 880 199 320 21 44 47 35 45 1496 19 32 27 43 10 16 0 0 21 1 383 - - Antarox CO 880 45 34 32 2674 30 41 11 0 12 41 - The data indicate that, except for hydrogen chloride on the Antarox CO 800 containing coatings, the extent of interference from the various gases is low.The high response to hydrogen chloride by the Antarox CO 880 containing coatings is attributed to the formation of hydrogen bonds with the ethoxylate oxygen atoms. The fact that the frequency returns to the base line value indicates that this interaction is reversible. However, there would be interaction between hydrogen chloride (or acidic component) and any ammonia in a sample stream. The large frequency change brought about by hydrogen chloride for the Antarox CO 880 coated crystal suggests that Antarox CO 880 could be a suitable piezoelectric sensor for this gas and is now under investigation. The large frequency change brought about by hydrogen chloride for the Antarox CO 880 coated crystal suggests that Antarox CO 880 could be a suitable piezoelectric sensor for this gas and is now under investigation.Application of the Sauerbrey Equation The analytical utilisation of coated piezoelectric quartz crystal detectors has been based on the assumption that Sauerbrey’s equation (quoted above) is valid, that is, that the mass increase caused by sorption is analogous to the concentration of the sample in the flowing gas stream and is proportional to the decrease of the resonance frequency. 1 However, analysis of previously obtained data by Beitnes and SchroderJ shows that the sensitivity of piezoelectric crystal detectors for flowing gas streams does not obey the Sauerbrey equation.Thus, despite the considerably poorer sensitivities that should follow from incomplete sorption on the crystal coating, mixing effects with carrier gas, etc., the observed decreases in frequency are often greater than the value corresponding to Sauerbrey’s equation. Conversely, observed decreases in frequency relate. according to the Sauerbrey equation, to mass changes that are greater than can be sorbed under the prevailing conditions. and in some instances greater than the amount of the component sought in the sample (see Table 3). Table 3. Comparison of ammonia present in 5cm-7 sample according to dilution and ammonia calculated from the frequency change by the Sauerbrey equation to be sorbed on the piezoelectric crystal coating.Slope of log AF versus log[NH3] graph = 0.194 for 300-0.3 p.p.b., and 0.355 for 3000 and 300 p.p.b. Concentration of NH, in sample, p.p.b. 3848 463 56 6.7 0 80 Ammonia calculated to be (for A = 0.549 Ammonia sorbed on coating present in 5 cm3 A F/Hz sample/pg cm2)/pg 289 19.2 0.85 136 2.30 0.40 84 0.28 0.25 56 0,033 0.16 39 0,004 0.11 Even greater anomalies than exist between columns 3 and 4 of Table 3 occur for higher values of AF, e.g.. for the 0.01 p.p.b. ammonia sample of Hlavay and Guilbault’ with a AF of 386Hz, the ammonia calculated to be sorbed by the pyridoxine hydrochloride coating is about 1 pg compared with the 0.000 05 pg deemed to be present in the 5 cm-7 sample used.The log A F versus log AC graphs (where Cis concentration) should have a slope of unity. Some previously reported double logarithmic plots for the piezoelectric detection of ammonia5 gave slopes of 0.0615 for a coating of L-glutamic hydrochloride and 0.0978 for a coating of pyridoxine hydrochloride. In the present study, the slopes are also considerably less than unity, being between 0.156 and 0.206 for the data in Table 1 and 0.194 for those in Table 3 lying in the p.p.b. range and 0.355 at the higher end of the range. The low slopes cannot readily be explained, although the fall-off in the response slope with time implies that the quality of the coating has a role. Data such as the above have led Beitnes and Schroder4 to investigate the systematic errors in the syringe dilution method because of the likelihood of sorptions on the syringe walls between dilutions.However, the magnitude of the anomalies between columns 3 and 4 in Table 3 and the other data cited above, and the ease with which blank values can be obtained from syringes that have been used for syringe dilution, suggest that other factors are involved. Alternative dilution methods, such as bottle dilution, also give sensitivities that are better than predicted.4 Clearly the above observations call for further study and Beitnes and Schroder are already looking at the nature of the coating and the calibration methods in order to account for such deviations from Sauerbrey’s fundamental equation. Conclusion The use of a nonylphenoxypolyethoxylate (Antarox CO 880) as a support polymer prolongs the life of pyroxidine hydro- chloride as a sensitive sorbent coating during the piezoelectric crystal detection of ammonia.However, the matrix system is a source of possible interference from hydrogen chloride gas, the high level of interference suggesting a role for the poly-ANALY‘I’ICAL PROCEEDINGS. IANUARY 1985. VOL 22 13 ethoxylate as a selective piezoelectric crystal coating for hydrogen chloride. The extreme sensitivity of the piezoelectric crystal detection of ammonia to below the p.p.b. range (into the parts per 10’’ range) and its nature are inconsistent with the Sauerbrey equation, which normally applies to straightforward depo- 1. 2. 3 , 4. sitions on piezoelectric transducers. This merits the further studies now in progress.J 5 .References Guilbault. C;. G., lon-Sel. Electrode Rev., 1980. 2, 3. Sauerhrey. G . Z . . 2. I’hys.. 1059. 155, 206. Moody. 6. J . . Thoma\. J . D. R . , and Yarmo. M. A., Anal. Chini. Acta. 1983, 155. 225. Beitnes, H . . and Schroder. K . , Anal. (’him. Acta, 1984. 158,57. Hlavay, J . . and Guilbault. C . G.. ,4nal. Chem.. 1078. 50, 1044. Solvent Extraction Studies of Metal - Polyalkoxylate Complexes in Relation to Electrochemical Response Philip H. V. Alexander, Gwilym J. Moody and J. D. R. Thomas Applied Chemistry Department, Redwood Building, UWiST, P.O. Box 13, Cardiff, CF1 3XF The tetraphenylborates of metal ion - polyalkoxylate com- plexes are well established as ion-selective electrode sensors for cations such as barium and calcium.when the sensors are incorporated with a suitable solvent mediator in a liquid membrane or a PVC matrix membrane. The PVC matrix membrane electrodes have also found use in the measurement of polyalkoxylates in solution and for the determination of the critical micelle concentrations (cmc) of polyalkoxylate non- ionic surfactants. 1.2 The mechanism of the potentiometric response of the electrodes towards polyalkoxylate has not been characterised, but it is assumed to involve barium. Also, it is known that the tetraphenylborate of the barium complex with the nonylphe- noxypolyethoxylate, which has just 4 ethoxylate units (Antarox CO 430), is a more effective sensor for alkoxylates in solution than is the tetraphenylborate of the longer chain analogue, Antarox CO 880, which has 30 ethoxylate units and which is better at selectively sensing barium ions.’.’ These observations suggest that the electrode response varies accord- ing to the stability of the metal - polyalkoxylate complex concerned.An earlier study3 has shown that solvent extraction proce- dures are helpful in determining the relative order of stability of these metal ion - polyalkoxylate complexes. Here. the cationic complex formed in the aqueous phase is extracted into the organic phase, together with an easily polarisable coloured anion, such as picric acid. The amount of complex thus extracted is determined spectrophotometrically . In the present study, the bulk extraction coefficients of several divalent cation - polyalkoxylate systems have been determined and related to the response of PVC matrix membrane electrodes prepared from the tetraphenylborate salts of certain of these complexes.Solvent Extraction Studies The polyalkoxylate systems studied are listed in Table 1, together with their principal features. In addition to Antarox CO 430 and Antarox CO 880, which had previously been used in electrodes, these included Antarox CO 730 to exemplify a polyethoxylate of intermediate chain length, PEG 1500 as a close analogue to Antarox CO 880 but lacking the hydrophobic grouping, and two propoxylates, Glucam P10 and Glucam P20. The bulk extraction constants into dichloromethane with respect to barium, magnesium and zinc ions were determined for each polyalkoxylate, according to the principles and method previously described’ for picrate as the coloured polarisable anion, except that in this study dipicrylamine was the coloured anion.Dipicryalamine was selected because, except for Antarox CO 880 and Antarox CO 730, little or no extraction was observed with picrate. It has previously been shown that dipicrylamine extracts crown ether - metal com- plexes about one hundred times more powerfully than picric acid.4 Also, the spectrophotometric absorption coefficients in the aqueous (at 429nm) and organic (at 421 nm) phases are much greater for this anion. Table 2 summarises the principal solvent extraction data and the bulk extraction constants, Ki, the units of K , being related to the stoicheiometry of the relevant metal ion - polyalkoxylate complex. It is difficult to compare the different groups of Ki data because of the differences in units.Also, much higher concentrations of alkoxylate have had to be employed for Antarox CO 430, Glucan P 10 and Glucam P 20 in order to obtain sufficient extraction of the dipicrylamine. Nevertheless, it can be seen that the metal ions complex strongly with Antarox 430 and Antarox CO 730 when compared with Glucam P 10, although the low complexation of zinc ions with Antarox CO 730 is anomalous. Barium forms the strongest complex for each polyalkoxylate except for the Glucam P 10 systems, where the magnesium complex is the strongest. Zinc forms the weakest complexes of each group except for Antarox CO 430 and Glucam P 20. Potentiometric Studies PVC matrix membrane electrodes based on sensors made from the tetraphenylborates of the various metal polyalkoxylates in 2-nitrophenyl phenyl ether as solvent mediator confirm that the best barium ion-selective electrodes are based on Antarox CO 430, as previously described.1.2 The electrodes recommen- ded for use in ethoxylate analysis in aqueous solutions are those based on a “liquid ion-exchanger,” consisting of a Table 1. Features of polyalkoxylates studied Commercial name Antarox CO 430 Antarox UO 740 Antarox CO 880 PEG 1500 Glucam I’ 10 Glucam P 20 Nature o f alkoxylate and number of units Ethoxylate (4) Ethoxylate (15) Ethoxylate (30) Ethoxylate (34) Pro pox y la t e (10) P r opox y I at e (20) Nature of hydrophobe Nonylphenoxy Nonylphenoxy Nonylphenoxy None Methylglucoside Methylglucoside Average relative molecular mass 396 880 1540 1500 775 1355 Ba2 + : AOU ratio 4 1s 12 10.5 10 814 ANALYTICAL PROCEEDINGS, JANUARY 1985.VOL 22 Table 2. Extraction of dipicrylamine into dichloromethane by polyalkoxylates in the presence of barium, magnesium and zinc ions with bulk extraction constant ( K , ) data. [M?+] = mol dm-3. Equal volumes (10 cm-i) of water and dichloromethane Alkoxylate Antarox CO 730 PEG 1500 Antarox CO 880 Antarox CO 430 Glucam P 10 Glucam P 20 [Alkoxylate]i 0.703 1.38 x 106 1.38 X 10' 0.55 0.600 3.61 0.70 0.27 0.636 2.29 0.58 0.04 7.58 1.94 x 10' 6.68 x 10' 10-5 mol dm-' K, 1.59 X 103 1.12 47.2 184 7.86 2.07 9.46 7.08 8.05 Dipicrylamine Units of K , extracted, Yo moi- I dm? 92.2 61.9 7.9 51.9 40.2 32.4 40.6 30.3 17.90 mol- 1 dm' 64.2 53.8 61.9 mol- dm' 20.6 28.8 16.4 mol-0 1 dml 2 62.2 59.4 60.1 mol- (1 -3 dm0 'I mol- (1 1 dml 2 Dipicrylamine extracted [alkoxylateji 106% mol- I dm' 13.1 8.8 1.1 8.7 6.7 5.4 6.4 3.8 2.8 0.85 0.71 0.82 1.8 2.6 1.5 3.0 2.9 2.9 - saturated solution of the tetraphenylborate of barium - Antarox CO 430 complex in 2-nitrophenyl ether.Table 3 illustrates the responses to barium, magnesium and zinc ions of PVC matrix membrane electrodes that have been prepared using the tetraphenylborates of selected metal polypropoxylates in complexes involving Glucam P 10 and P 20 as sensors with 2-nitrophenyl phenyl ether as the solvent mediator. In no instance was a good response obtained for either magnesium or zinc, despite the indications from the K, data of Table 2 that complexes involving Glucam P 10 and Glucam P 20 might show potentiometric sensing properties for these ions.A barium ion response was evident in all instances, although these did not approach the quality of response characteristic of the established system5 based on the tetra- phenylborate of the barium complex with Antarox CO 880. Glucam P 10 and Glucam P 20 polypropoxylates cause a less than lOmV change in the potential over three decades of polypropoxylate concentration for electrodes based on sensors of either barium - Antarox CO 430 or barium - Antarox CO 880 complexes compared with the -30mV e.m.f. per decade change given by the Antarox polyethoxylates near the cmc region. However, electrodes employing polypropoxylate - barium complex sensors gave e.m.f. changes of -10mV per decade for Glucam P 10 and -25 mV per decade for Glucam P 20, but this is still dwarfed by the much bigger response (-120mV per decade) given by these electrodes towards Antarox CO 880.Correlation of Potentiometric and Solvent Extraction Studies Antarox CO 880 forms the basis of a very good barium ion-selective electrode. This accords well with the Ki value for the barium complex and with the good extraction of the complex into the organic phase, as depicted by the dipicrylam- ine extraction. Although this electrode system gives e.m.f. changes for alkoxylates in aqueous solutions, it is inferior to the Antarox CO 430 electrode system for this purpose. The better performance of the barium - Antarox CO 430 system as an electrochemical sensor for polyethoxylates may be due, in part, to the relatively poor affinity exhibited by the organic phase for this complex, as depicted by the dipicrylamine data in the last column of Table 2.Also, just four ethoxylate units are complexed to the barium cation, compared with the larger number of ethoxylate units complexed for other members of the Antarox series, which promote the transfer of the polyethoxylate being sensed towards the barium ions in the membrane. The high extractions of the dipicrylamine of the Antarox 730 and of the PEG 1500 systems do not lead to good electrode qualities for polyethoxylates, although the barium complex with Antarox CO 730 is a good potentiometric sensor towards barium ions. For the Glucam polypropoxylates, the somewhat higher extractability of the dipicrylamine of these systems compared Table 3. Responses of electrodes with metal - polypropoxylate sensors to selected divalent ions. No response times are quoted as stable responses are usually unobtainable Electrode sensor type Ba2+ (BaCL) MgZ + (MgC1,) ZnZ+ (ZnS04) (Glucam P 20)0.4 - Ba - TPB2 (Glucam P 20)" - Zn - TPB2 (Glucam P 20)(,,4 - Mg - TPBz Glucam P 10 - Ba - TPB, Poor, 5 x 10-4-10-1 -20 mV decade-' Linear response z= j x 10-5-10- 1 ~ 2 0 - 2 2 mV decade- Linear response = 19 mV decade - I Poor, linear response 5 x 10-"10 I = 18 mV decade- 1 =5 x 10-s-15 x 10-2 Minimal Minimal Minimal Poor Poor, non-linear, Minimal erratic Minimal Virtually noneANALYTICAL PROCEEDINGS, JANUARY 1985. VOL 22 15 with Antarox CO 430 systems is matched by the greater response given by the Glucam electrode system towards the polypropoxylate noted above. Also, the response of the Glucam electrode system towards Antarox ethoxylates is much greater in magnitude than is observed for the Antarox electrode systems, but the reproducibility and linearity of the AE versus log [Antarox] relation is poor. It is noted that Glucam P 10 and P 20 have fewer alkoxylate units per barium ion in the sensing complex than is the case for the barium complex with Antarox CO 880. Conclusion There are some inter-relations between the potentiometric electrode responses given by sensors based on the tetraphenyl- borates of metal complexes with polyalkoxylates and the solvent extraction parameters of the dipicrylaminates of these complexes. However, this does not adequately explain the superiority of electrodes containing the barium complex with Antarox 430 for sensing polyethoxylates, nor of the good barium ion-selective electrodes derived from the complex of barium with Antarox CO 880. More complete answers to these phenomena may lie in solvent extraction studies with tetra- phenylborates, rather than picrates or dipicryIaminates, and with 2-nitrophenyl phenyl ether soIvent rather than with dichloromethane, although this aromatic ether solvent is poor as a background spectrophotometric medium. The authors thank the Science and Engineering Research Council €or a studentship (to P.H.V.A.) under the Coopera- tive Awards in Engineering Scheme in conjunction with Unilever Research, Port Sunlight Laboratory. References 1. 2. 3 . 4. 5 . Jones, D. L., Moody. G. J.. and Thomas, J . D. R.. Analyst, 1981, 106, 439. Jones, D. L., Moody, G. J . , Thomas, J . D. R . , and Birch, B. J . , Analyst, 1981, 106, 974. Jaber, A. M. Y., Moody, G. J.. and Thomas, J . D. R., J . Inorg. Nucl. Chem., 1977, 39, 1689. Jawaid, M., and Ingman, F., Talanta, 1978, 25, 91. Jaber, A. M. Y.. Moody. G. J., and Thomas. J. D. R.. Analvst, 1976, 101. 179.

ISSN:0144-557X    

DOI:10.1039/AP9852200003

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, JANUARY 1985. VOL 22 Flow Injection Analysis with Chemiluminescence Detection : Determination of Hydrazine Azad T. Faizullah and Alan Townshend Department of Chemistry, University of Hull, Hull, HU6 7RX Flow injection analysis (FIA) is inexpensive to implement and effectively measures chemiluminescence during the first few seconds of a chemiluminescent reaction. Therefore it is well suited to rapid analysis. Different types of flow systems have been designed for use with chemiluminescent detection l-6 and the various flow cells used in these analyses have been reviewed.’ In the present work a detector for monitoring such reactions is described, which is able to measure low light emissions produced by some chemiluminescent systems, such as the oxidation of hydrazine with hypochlorite, using FIA.Its use for the determination of traces of hydrazine, and an investigation of the effect of metal ions on this procedure, is described below. Instrumentation A detector was designed by Wheatley8 for monitoring chemilu- minescent reactions by FIA. Substantial modifications have been made for the present investigations, which have resulted in the detector described below. It consists of a stainless-steel housing with a Perspex T-piece for creating rapid and efficient mixing of the sample and reagents, which minimises the inordinate tailing that is produced by other means of mixing. The T-piece leads immediately to the centre of a coiled flow cell, for maximising light collection. The flow cell is made by winding the desired length of glass tubing (0.8 mm i.d.) and fixing it on a piece of aluminium foil on the surface of a black Black Perspex tubing T-piece w OUtDUt Black plate 1 Waste - Flow-coil cathode h Main Fig.1. its design) Detector housing (flow coil turned through 90” to illustrate plate which then separates the T-piece from the flow coil. The light emitted is measured by an end-window photomultiplier tube (EM1 Model 9844B). Black tubing was used for the external connections to the T-piece in order to eliminate any light piping effect. The whole assembly is shown in Fig. 1. The new detector was tested by using the metal catalysed oxidation of lurninol by hydrogen peroxide .6 Typically, the relative standard deviations of 10 replicates was <2% and as little as 0.3 ng of metal ion (Co2+, Cu2+) could be detected.Metal Inhibition and Activation in Chemiluminescence It was found8 that the oxidation of hydrazine by hypochlorite was chemiluminescent, and used this reaction in a flow injection procedure to determine >10-X M of hydrazine. The FIA arrangement shown in Fig. 2 has been used for this purpose. Hvdrazine (3 Buffer pH 11.5 NaOCl x TO- MI Fig. 2. Flow injection manifold for hydrazine determinationX Some metal ions exert inhibition or activation effects on this reaction. These have been investigated by use of the flow system shown in Fig. 2, modified by incorporating an addi- tional stream in which particular metal ions are pumped also at 1.5 ml min-1 and mixed with the hypochlorite stream before entering the T-piece.Cobait(II), copper(II), manganese(T1) and chromium(II1) were found to inhibit the reaction, while others (Ni2+, Zn2+, Cd2+ and Al”) gave increased intensities. Some of the results are shown in Fig. 3. The reasons for these effects are not known. The enhancing effects, however, can be used to provide a more sensitive method for determining hydrazine. When a stream of 0.116 ANALYTICAL PKOCEEDINGS, JANUARY 1985. VOL 22 40 I I C v) .- .- E u1 Fig. 3. Effects . 30 20 10 0 ( a ) 5 10 15 0 Concentration of metal ions, p.p.m. L .- c - 2 -1.5 -1.0 -0.5 0 0.5 1.0 Log,dM”* ), p.p.rn. of metal ions on the chemilumincscence at hydrazine concentrations of: ( a ) , 5 x It) ’ M ; ( h ) , 5 x 10 (’M A 10-4 M hydrazine 10- M hydrazine 5 x M hydrazine 2.5 x 10-6 M hydrazine 10-6 M hydrazine t 5 x 10-7 M hydrazine I I I I 0 - 2 - 1 0 1 2 LogIo[Al3 + I, p.p.m. Fig. 4. Effect of AP+ concentration on emission signals after removal of metal ions on Dowex A-1 p.p.m. nickel solution is introduced in the above arrangement, for example, the detection limit is 5 X 10-10 M of hydrazine compared with 3 x 10-8 M without added catalyst. Interesting though the effects of metal ions are, the presence of certain metal ions interfered with the determination of hydrazine. In order to combat this effect, the incorporation of miniature ion-exchange columns in the plan system was investigated. Anion, cation and chelating ion-exchange resins were studied by incorporating the column after the sample introduction valve. The chelating resins (Dowex A-1 or Chelex 100) were most effective in removing metal ions, so effective that incorporating two Dowex A-1 columns (25 cm X 2.4 mm i.d.) in the hypochlorite stream completely prevented the chemiluminescent reaction.This indicated that certain trace metal ions were necessary in order to stimulate the chemilu- minescen t oxidation of hydrazine. Having removed interfering metal ions in this way, it was possible to stimulate the chemiluminescence even more sensitively by addition of traces of certain metal ions (Nizf, Zn+ and Al”). Aluminium is particularly effective, and gives a sensitivity enhancement over the original chemiluminescence of 3 orders of magnitude. The effect of aluminium is shown in Fig. 4. A. T . Faizullah is grateful to the University of Salahaddin, Iraq, for a grant to carry out this work.References Nall, V., and Nieman, T. A.. Anal. Chem., 1978. 50, 401. Schroeder, H. R.. and Yeager, F. M . , Anal. Chem., 1978. 50. 114. Schroeder, H. R., and Volgelhut, P. O.,Anal. Chem., 1979,51, 1583. Schram, E . , Roosens, H.. and Van Esbroeck, H., in Stanley, P. E., and Schram, E . , Editors, “Proceedings of the Interna- tional Symposium on Analytical Applications of Biolumines- cence and Chemiluminescence,” 1979, p. 689. Scott. G., Seitz, W. R . , and Ambrose, J . , Anal. Chim. Acta, 1980, 115,221. Burguera, J . I-., Townshend. A.. and Greenfield, S . , Anal. Chim. Acta, 1980, 114, 209. Seitz, W. R., CRC Crit. Rev. Anal. Chem., 1981, 13, 24. Wheatley, A., PhD Thesis, Llniversity of Hull, 1982. 1. 2. 3. 4. 5 . 6. 7 . 8.Monitoring of lmmunoprecipitin Reactions Using Flow Injection Analysis Arwel Hughes Department of Chemistry, Sheffield City Polytechnic, Pond Street, Sheffield S 1 I WB and Paul J. Worsfold Department of Chemistry, University of Hull, Cottingham Road, Hull HU6 7RX The quantitative determination of proteins by immunoprecipi- significant serum proteins, detection based on immunoprecipi- tation was first reported in 1935. Since that time a number of tation has several advantages. The reaction can be followed by more sensitive immunoassay techniques have been developed, use of a simple spectrophotometer; no label is needed and, e . g . , radioimmunoassay, enzyme immunoassay and fluores- therefore, the reaction is monitored directly. Also there is no cence immunoassay, but in applications where high sensitivity separation stage so the procedure is readily automated.is not required, e . g . , for the analysis of most clinically The technique is based on the formation of aggregatesANALYTICAL PROCEEDINGS. JANUARY 1985. VOL 22 17 between bivalent antibody and multivalent antigen molecules, which induce light scattering, so that an increase in turbidity is observed. The relationship between the antigen concentration and the amount of antibody precipitated is known as the immunoprecipitin curve. It is linear, and therefore quantita- tive. up to a certain antigen concentration owing to the increasing amount of cross-linking between antibody and antigen (the antibody excess region). The curve then passes through a plateau region (the zone of equivalence) wherein equivalent numbers of antibody and antigen binding sites are available.As the antigen concentration is further increased, there is competition for antibody binding sites. the average size of the aggregates falls and hence light scattering decreases (the antigen excess region). It has previously been reported that flow injection analysis (FIA) coupled with turbidimetric detection provides a precise, rapid and simple system for the study of a model immunopre- cipitin interaction.2 This paper describes an automated merg- ing zones FIA procedure for the determination of a high relative molecular mass protein, human serum IgG,via its interaction with goat anti-human IgG and based on rate turbidimetry . Experimental Goat anti-human IgG antiserum (Atlantic Antibodies; 2 ml) was prediluted 80 times, and human IgG calibrator serum (Atlantic Antibodies) 800 times, with polyethylene glycol (40gl-1) - sodium chloride solution (9gl-1) as the diluent in both instances. The merging zones manifold used here was as previously described.2 In this instance the working antiserum (30 pl) and human serum (30 p1) standards were simultaneously injected into separate carrier streams of PEG - sodium chloride solu- tion pumped at 0.5mlmin-~.The two zones were synchro- nously merged and passed through a coil packed with glass beads into the flow-cell of a spectrophotometer (340nm). A segment of the merged zones was stopped in the flow-cell 14s after injection for a period of 60 s. A two-point kinetic analysis was then performed by taking readings 44 and 74s after injection.Automation of the system was as previously described? with two modifications. Antigen samples were introduced into the injection valve automatically via an autosampler, and a separate computer controlled peristaltic pump was used to introduce antibody into the injection valve. Results A calibration graph was obtained for human serum IgG over the range 0-3556 mg dl-1. Under the conditions described above there was a linear relationship (correlation coefficient 0.985) between reaction rate and IgG concentration over the range 0-2844 mg dl-1 and a decrease in reaction rate over the range 2844-3556 mg dl-1. The relative standard deviations (YO) for within-batch ( 5 replicates) and between-batch (15 repli- cates) precision in the antibody excess region were 24'/0 and 2--6%, respectively. These results demonstrate the characteris- tic immunoprecipitin response described above and suggest that quantitative results can be obtained over a useful clinical range.The linear range and sensitivity can be modified to suit particular requirements, either by varying the dilution factors for the antibody and antigen or by using asynchronous merging zones. The sample throughput for human serum IgG using the above manifold was 40 samples h-1. A comparison of the analytical performance of the FIA technique with that of radial immunodiffusion (RID) is currently being undertaken and will be the subject of a future publication. Discussion Refinements to the manifold used to study a model immuno- precipitrn reaction2 were made when analysing to determine IgG in order to improve the sensitivity of the reaction and to reduce the amount of expensive antiserum consumed.Firstly, the carrier stream and the diluent for both antibody and antigen contained polyethylene glycol (40 g 1-1) in order to enhance the formation of large molecular aggregates and to increase the sensitivity. This, in turn, increased the sample throughput (40 samples h-I), with the results for any sample being available less than 2 min after sample injection. The use of highIy viscous carrier streams, however, led to poor mixing between the merging zones, and a drifting signal resulted. This tendency was overcome by the introduction of a mixing coil, in this instance a packed glass bead column, between the confluence point and the detector.Secondly, a separate automated peristaltic pump was used for the delivery of expensive antibody into the injection valve (30 pl), in order to minimise the amount of reagent waste during the loading procedure. The feasibility of using FIA to monitor immunoprecipitin interactions has been demonstrated and the results compare favourably with existing techniques in terms of linear range, precision, sample throughput and cost. The manifold can easily be modified to suit the requirements of a particular analysis and the application range could be extended to include other serum constituents present at sufficiently high concentrations, e.g., certain therapeutic drugs and blood group indicators. The sensitivity could be increased by changing the dilution factors of the antibody or antigen or by the use of laser-nephelometric detection.Alternatively, more sensitive homogeneous im- munoassay techniques, based on enzyme and luminescent labels, could be coupled with FIA in order to provide a cheap, easily automated immunoassay system with rapid response times. References 1. 2. Stenberg. J. C.. Int. Cfin. Prod. Rev., 1984, 3, 16. Worsfold, P. J . , and Hughes, A., Analyst, 1984, 109, 339. Concentration Gradients for Calibration Purposes J. F. Tyson and J. M. H. Appleton Department of Chemistry, University of Technoiog y, Loughborough, Leicestershire, LE 7 1 3TU Atomic-absorption spectrometry has been widely used in trace metal analysis over the last 30 years. During that time, successive generations of atomic-absorption spectrometers have been developed, yielding the modern sophisticated instruments of today, with their wide range of capabilities to assist the analyst.However, because no absolute mathematical relationship exists between absorbance and analyte concentration, the fundamental need for calibration remains. Indeed, it consti- tutes a major part of the analysis, involving the time consuming preparation of a range of suitable standards, the recording of their absorbances and the construction of a calibration graph. In many modern instruments, the calibration graph is deter- mined by a dedicated microcomputer, which fits an equation to the absorbance - concentration data. The procedure assumes that the calibration graph has a particular mathemat- ical form and thus, once this form has been assigned, the calibration process is limited to the best fit that a particular model can produce.The accuracy of calibration will thus depend upon the complexity of the absorbance - concentration18 Volume Vi of standard C, ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 ~~ Fig. 1. Simple flow injection manifold. C, is the concentration of the standard; V , is the volume of standard injected; L is the length of the delay coil; C, is the resulting peak concentration entering the detector relationship, the mathematical model applied, the number of standards employed and the extent of the working concentra- tion range.’ Whilst being slow by comparison, the traditional method of plotting a graph of absorbance against concentration has some inherent advantages.Unrestricted by prior assumptions about curve shape, it is totally flexible and capable of good accuracy if a large number of standards is employed to define the curve. In the past, however, one invariably compromised on this point, owing to the labour involved, and settled for the minimum number of standards acceptable. Thus, the number of stan- dards involved, their preparation and presentation, and the evaluation of the data generated, constitutes the major limitation of this method. A most welcome improvement to conventional calibration practice would be the introduction of a procedure which enabled these functions to be carried out rapidly and efficiently without compromising calibration accu- racy.To this end, the prospects of producing standard concentrations by high-speed, flow injection and continuous flow methods, with computer processing of the results, were investigated. When using a flow injection system,2 the extent to which an injected standard is diluted by the carrier stream can be controlled by varying the volume injected, Vi, or the manifold length, L (Fig. l).3 Preliminary experiments indicate that such systems may be used to produce a range of dilutions for calibration purposes. However, this particular application is complicated by the atomic-absorption spectrometer’s peculiar response to dynamic inputs.4 Nevertheless, recent work has revealed that the normal working concentration range of a spectrometer can be extended by several orders of magnitude, using peak width as a basis of instrument calibration.5 One particularly simple and attractive technique is continu- ous dilution calibration,6 which employs a well stirred mixing chamber to generate a standard concentration gradient.When a stream of concentrated standard is switched into the water filled chamber, the effluent concentration varies with time according to equation (1). C = C,[1 - exp(-u.t/v)] . . . . (1) where Cis the concentration of the tank effluent at time t ; C, is the original standard Concentration; u is the volumetric flow-rate; and V is the volume of the chamber. This effluent is led directly to the nebulizer of the spec- trometer and the growth of absorbance with time is monitored using a chart recorder or a microcomputer.The record provides the instrument output, A , at any time t , whilst equation (1) provides the corresponding concentration input, C. The combination of the two links absorbance and concentra- tion over the entire concentration range recorded (see Fig. 2). Samples are pumped directly to the nebulizer at the same flow-rate, by-passing the mixing chamber. The sample concen- tration, C,, is determined from the absorbance, A,, by locating the characteristic time, t,, and substituting it in equation (1) (see Fig. 2). -Time t Fig. 2. Continuous dilution calibration: chart recording of growth of absorbance with time, and the determination of C, from sample absorbance A,. C, is the concentration of the standard solution; u is the volumetric flow-rate; V , is the volume of the mixing chamber Experimental A continuous dilution calibration system (Fig.3) was built around a PTFE mixing chamber of cylindrical section and with a slightly domed top to allow escape of air bubbles. The chamber was mounted on a Gallenkamp, Model SS615, magnetic stirrer and housed a PTFE-covered follower. The effective volume was 7.2 cm3. A flow-rate of 8.0 cm3 min-l was maintained by a Gilson Minipuls I1 peristaltic pump. The 128K Apple IIe microcomputer, equipped with an Epson MX 80 type 111 printer, was interfaced to the Shandon Southern A3300 atomic-absorption spectrometer by means of a home-made signal-conditioning unit (variable amplification and back-off) and a 12-bit Micro Control Ltd. analog to digital converter card. Operated in the free-running mode, this arrangement enabled recording of the absorbance at a frequency of 72.58 Hz.Thus, 4000 absorbance readings were recorded in about 5 5 s , during which time the concentration input to the spectrometer increased continuously from zero to about 64% C, ( L e . , zero to about absorbance 1.6 when a 3p.p.m. magnesium solution was used as the standard). Programming was entirely in BASIC and included identifica- tion of the start of the calibration run, recording and smoothing of the calibration data, measurement of sample absorbanee, determination of sample concentration and printing of the results. Smoothing, by a modified Savitsky - Golay routine, was designed to remove short-term flame and electronic noise without significantly modifying calibration graph shape.The sample signals were integrated over about 5 s by calculating the mean of 400 readings, Test elements were chosen to illustrate a variety of behav- iour with respect to atomic absorption. Magnesium was chosen for its high sensitivity and for the limited curvature of its conventional calibration graph, nickel as an element exhibiting pronounced curvature of the calibration graph and chromiumANALYTICAL, PROCEEDINGS, JANUARY 1985, VOL 22 m Standard, c" 1 k Sample Waste 9- Water I Signal, A I I I Micro- I computer Fig. 3. Arrangement of apparatus for continuous dilution calibration because of its reported calibration irregularities.7 The stan- dards and test samples were prepared from 1000p.p.m. commercial stock solutions (BDH Chemicals Ltd).Results and Discussion Typical results for magnesium, nickel and chromium are presented in Tables 1-3 and compare favourably with conven- tional atomic-absorption determinations. Work is now in progress to make a full evaluation of the accuracy of the Table 1. Results for magnesium Magnesium concentration. p.p.m. C,,p.p.m. 0.25 0.50 1.00 1.50 2.00 5 0.2s 0.48 1.00 1.50 2.02 10 0.26 0.50 1.01 1.52 2.04 3 0.25 0.49 0.99 1.48 - Table 2. Results for chromium Chromium concentration, p.p. m. Cm9p.p.m. 2.0 4.0 6.0 10.0 15.0 20.0 25 1.99 3.99 5.94 10.1 15.3 20.6 50 2.06 4.07 6.10 10.1 15.2 20.4 75 2.09 3.95 5.86 9.8 15.1 20.0 Table 3. Results for nickel Nickel concentration. p.p.m. Cm,p.p.m, 10 20 30 4Q 50 75 100 10.3 20.6 31.0 41.2 51.5 77.7 200 10.3 20.7 30.6 40.7 50.4 75.8 19 method, and to determine its limitations.At present, the day to day relative standard deviation i s about 0.7% for the greater part of the working concentration range. Conclusions The advantages of the method are that it is simple, rapid and accurate, and can be easily automated. Calibration involves no curve fitting, is independent of the shape of the conventional calibration graph, and extends over the entire working concen- tration range. No internal instrument modification is required and the calibration principle is applicable to other techniques. It is hoped that the investigation will lead to the introduction of fully automated atomic absorption calibration systems incorporating constant flow-rate, electronic timing and a programmed valve switching sequence, with assembly- language routines to increase the rate of data collection and processing. Thus, the appearance of atomic-absorption spec- trometers with a push-button calibration facility is entirely possible in the near future.Financial support for J. M. H. Appleton by the SERC is gratefully acknowledged. References 1. 2. 3. 4. 5 . 6. 7. Tyson, J . F,, Analyst, 1984, 109, 313. Betteridge, D., Anal. Chem., 1978, 50, 832A. Ruzicka, J . , and Hansen, E. H . , Chem. Technol.. 1979 (12). 756. Tyson, J . F., and Appleton, J . M. H., A n d . Chirn. Actu, to be submitted. Tyson, J . F., Analyst, 1984, 109,319. Tyson, J . F., and Appleton. J. M. H., Tulantu, 1984. 31, 9. Thompson, K. C,, Analyst. 1978, 103, 1258. The Flame Atomization of Molybdenum J. F.Tyson and L. L. Sarkissian Department of Chemistry, University of Technology, Loughborough, Leicestershire, LE 7 7 3TU The heteropoly acid chemistry of molybdenum is an attractive area for the development of indirect atomic-absorption proce- dures for the heteropoly forming elements as these elements are often difficult to determine by direct atomie-absorption methods. Existing flame based methods are limited by (a), the rather high blank values due ta the presence of some of the large excess molybdenum added to drive the reaction to completion in the subsequent organic extract, ( b ) , the yield of the atom forming reactions in the flame and (c), the noise associated with nebulization and combustion processes. All of these factors have been studied with a view to improving the sensitivity and detection limit for molybdenum, using phos- phate as a made1 species.The effect of washing and drying the organic extract has been studied while madifications to the flame chemistry have been investigated, consisting of adding gases to increase the reduc-20 ANALYTICAL PROCEEDINGS, JANUARY 1985. VOL 22 ing properties of the flame. and adding various salts to modify the microclimate around the molybdenum during the atomiza- tion processes. Modifications to the nebulization processes have been investigated by using flow injection methodology and modifications to the solution physical properties have been studied. Experimental A Baird Atomic A3400 atomic-absorption spectrophotometer and a Datacomp Model A5195 computing integrator were used.The output from the instrument was also recorded by a Tarkan, Model 600, recorder. For the flow injection work, a single line (0.58 mm i.d.) manifold was used in which the carrier was pumped by an Ismatec mini S peristaltic pump. A Rheodyne-type 5020 rotary injection valve with an external loop volume of 200 PI was used. Additional flame gases were introduced via the supplementary support gas supply system. Phosphate was determined] by adding molybdate solution to a phosphate containing solution in a strong acid medium. After a few minutes the phosphomolybdic acid was extracted with an organic solvent, which was then washed with dilute acid to remove the excess molybdate transferred to the organic phase. The molybdenum content of the organic phase or of the back extract in ammonia buffer solution was determined by atomic absorption at 313.3 nm using either an air - acetylene or nitrous oxide - acetylene flame.Results and Discussion Washing the organic extract repeatedly with dilute acid failed to bring the blank level to below 1 p.p.m. of molybdenum. However, when the extract was dried by passage through a small column of anhydrous sodium sulphate the blank level was reduced to below the detection limit, about 0.2 p.p.m. This observation suggests that the blank levels are caused by molybdenum in aqueous phase droplets suspended in the organic solvent (butyl acetate), rather than co-extracted isopolymolybdic acid. The effect of separately adding hydrogen and carbon monoxide to both air - acetylene and nitrous oxide-acetylene flames was investigated.The mechanism by which molyb- denum atoms form in the flame appears not to have been completely characterised yet. L'vov et a1.2 assumed that the salt particles are reduced to carbide or metal in the primary reaction zone; these species are then vaporised and disso- ciated. Both species are relatively involatile. Alternatively, the route may be via the volatile oxide, which then undergoes thermal dissociation or reduction by flame species.3 As the sensitivity is about the same in both the nitrous oxide and air supported flames, and as the sensitivity is considerably improved if the flame is fuel rich, it seemed to us that the predominant route must be via chemical reduction of the oxide, as the increased temperature of the nitrous oxide supported flame has little effect (an enhancement would be expected if the route was via the involatile solid carbide or metal or involved thermal dissociation).The fuel rich require- ment also strongly suggests chemical reduction. The problem would seem to be that in a carbon-rich environment the competing side-reactions of carbide formation would also occur. It was hoped that adding hydrogen would provide a reduction mechanism that avoided carbon containing species. The commercial production of the metal proceeds via this process.4 Ottaway and Cokers reasoned that a probable candidate species responsible for the final reduction of the monoxide to the metal was CO; accordingly the effect of increasing the partial pressure of this gas was also investigated.Disappointingly, the addition of neither gas produced any increase in sensitivity; in fact the reverse was observed. However, the flame geometry was considerably changed with the formation of much larger primary reaction zones and it was not possible to lower the burner far enough to obtain a maximum on the graph of absorbance versus burner height for hydrogen. The reverse was the case for CO, with the maximum absorbance observed with the light beam grazing the burner top. The behaviour in both flames was similar. The reported enhancement of the molybdenum signal when aluminium salts were added to the solution6 was confirmed. The effect was somewhat concentration dependent but values of 3545% (NzO flame) were observed at low concentrations. A similar effect was observed with ammonium chloride.A range of other simple salts was investigated. Both depressions and enhancements were observed. The role of these added salts is somewhat complex and varied. In the instance of aluminium, it is thought that the salt decomposes to give an alumina particle with the molybdenum species dispersed in it. The alumina then decomposes, liberating oxygen, and reacts with carbon containing species to form a stable aluminium carbide, both of these helping to vaporize the molybdenum as the oxide by providing an oxidising microclimate and scaveng- ing carbide forming species. The ammonium salt particles are considered to disintegrate explosively7 providing very finely divided molybdenum species. Inert salts retard the vaporiza- tion if their melting-points are below the flame temperature, as the salt particle will maintain a temperature equal to the salt melting-point until all of the liquid has evaporated, by which time the particle may have travelled to a non-reducing part of the flame.The investigation into the effect of varying the physical properties of the solution produced varied results. Attempts to get a greater proportion of the nebulized solution into the flame in useful drop sizes by heating the aqueous solution (to about 80 "C) prior to nebulization produced an enhancement of about 40% in the nitrous oxide flame but no effect with the air flame. The addition of acetone (supposedly the best solventH) produced a marked depression in the air flame and an enhancement of 16% in the nitrous oxide flame. Aspiration of the butyl acetate extract produced a very severe depression. This solvent has been reported to give an enhancement of over 300% for copper.9 This latter solvent was introduced via the flow injection manifold.It has been reported*() that the use of a much reduced aspiration rate, discrete sampling and measurement of peak area can lead to improvements in detection limits over conventional nebulization because of firstly the substantial improvements in nebulization efficiency that occur at low flow-rates, and secondly, no loss in precision for peak area measurements compared with peak height measurements. However, investigations along these lines for a 200 1-11 sample volume and a pumping rate of 2 ml min-1 confirmed that peak area measurements (with a detection limit of 0.24 p.p.m.or 48 ng) were superior to peak height measurements but that both were inferior to conventional nebulization (detection limit 0.21 p.p.m.). Conclusions Although no major increases in analytical performance have been achieved in terms of sensitivity and detection limit, it is apparent that there is some scope for improving matters by careful design of the salt particle environment and the flame gas composition. Reduction of viscosity and desolvation of aqueous solutions also appear to offer some advances, but the role of organic solvents needs careful study as improvements in transports mechanisms may be more than offset by adverse effects on the flame chemistry. There is no doubt that sample introduction by flow injection methods is extremely conve- nient.The ability to handle small volumes can be advantageous in extraction situations where beneficial solvent volume ratios may be employed or where a limited amount of sample is available. The methodology has wider applications than just transporting the sample to the instrument,ll and at present the possibility of performing the whole of the formation, extrac-ANALYTICAL PKOCEEDINGS, JANUAKY 1985, VOL 22 21 tion. etc.. procedure in a flow injection manifold is being investigated. This may also prove to be a useful system for sample pre-treatment in methods using electrothermal atomi- zation. References 1 . 2. 3 . Hurford, ‘1‘. K., and Boltz, D. F., And. Chetrz., 1968. 40, 379. L’vov. B. V.. Orlov, N . A.. and Polzik.1. K., Zh. Anal. Khim., 1977. 32. 5 . Rubeska, 1.. and Palikanova, M., Spec1rochrm. Acru Purl R , 1978. 33B, 301. 4. 5. 6. 7. 8. 9. 10. 11. Cotton, F. A., and Wilkinson, F., “Advanced Inorganic Chemistry”, Second Edition, Interscience, London, 1966, p. 933. Coker, D. T., and Ottaway, J . M., Nature, Phys. Sci., 1971,230, 156. Rubeska. I . . Anal. Chem., 1976, 48, 1640. CIampitt, N . C., and Hieftje, G. M., Anal. Chem., 1972, 44, 1211. Christian. Ci. D.. and Feldman. F. J . , Can. Spectrosc., 1969,14, 1 . Allan. J. E.. Specfrochim. Acta, 1961, 17. 467. Wolf. W. R., and Stewart, K. K.. A n d . Chem., 1979,51, 1201. Tyson, J . F . , Analysr, in the press. Use of a Chromatographic Data Handling System Within a Pesticide Research Laboratory L. D. LeBorgne Shell Research Limited, Sittingbourne Research Centre, Sittingbourne, Kent, ME9 8AG The Analytical Chemistry Division (ACD) at Sittingbourne Research Centre provides analytical support to Shell’s research and development of agricultural chemicals.Much of these analytical data are generated by means of GLC and HPLC. These analytical processes generate considerable amounts of useful data and a Laboratory Automation System (HP3357) has been recently installed to provide a cost-effective opera- tion. This minicomputer can accept and rapidly process data from up to 60 analytical instruments, presenting the processed data in whatever form the user specifies. Facilities for instrument control, data storage and retrieval and re-analysis of data are available. Furthermore, scope exists for expanding the system to provide total sample management and reporting.Chromatographic techniques, particularly those of gas - liquid chromatography (GLC) and high-performance liquid chromatography (HPLC), are very important in the analysis of pesticides. In the past, data handling or capture of the resultant chromatograms was limited, initially by the time-consuming manual measurements and later by the relatively inefficient and slow response of electronic integrators. The problems associated with a lack of efficient and fast data handling, and the inability to store and manipulate digitised data, resulted in less extensive, more time-consuming analyses. Modern microprocessor controlled units offered. initially, dedicated integrators, which increased the scope but rapidly led to an undesirable proliferation of different systems.The Hewlett-Packard HP3357 laboratory automation system offered the facilities of data acquisition, storage and manipula- tion from a variety of analytical instruments. The capabilities of complete instrument control, sample data management, high quality graphics output for hard copy of results and chromato- grams and the use of high level languages (BASIC, FORTRAN, PASCAL,) for the development of programs were available. The system currently installed in ACD is interfaced to 45 chromatographs and supports 23 input - output devices for the interchange of data between system and user. These include a line printer for hard copy reports and chromatograms, an 8-pen graphics plotter and various CRTs with thermal printers including several with a graphics option.The system offers the following options for data capture, computation, presentation and storage of results: laboratory automation software (LAS); general laboratory computer; and database management. Laboratory Automation Software (LAS) The HP3357 LAS is a software package for acquiring, processing and storing analytical data generated by GLC, HPLC or other instruments. The system operates on a data communication loop, which interfaces the chromatographic instruments to the central processor unit. The chromato- graphic data from an instrument are collected by initiating an analogue to digital convertor (A/D), either manually or automatically, immediately upon injection of a sample solu- tion.The analogue signal generated by the detector is digitised by the A/D and transferred via the loop to the central processor unit (CPU), where it is stored in a Raw Data File. After each sample analysis the raw data are processed by using the information and parameters specified in a method previously allocated to the A/D channel and a report is generated. The integrated chromatographic data are stored in a Processed Data File. Therefore, to store all the chromatographic data from an analysis separate Raw and Processed Data Files must be allocated for each chromatogram. The methods, essential for processing the raw data, conform to a standard format. Users can specify chromatographic integration parameters, e.g., tangent skim, slope sensitivity, area summation, etc., to suit a particular analysis, with a choice of peak height or peak area computation.In addition, peaks can be identified and named, enabling quantitative calculations to be performed using the system’s pre-programmed, single- level calculation procedures. Alternatively, and particularly important to ACD where all analyses are performed by using multi-level calibration procedures, methods can call up from the memory user specified programs in order to provide processing or calculations directly applicable to the user’s requirements. One of the major advantages of a laboratory automation system, such as the HP3357, is the possibility of storing all of the raw data captured. This is most important in view of the increasing regulatory involvement in checking the quality of analytical experiments, e.g., environmental protection agen- cies and Good Laboratory Practice (GLP) requirements.This feature also enhances the user’s interpretation of analytical data, as raw data can be reprocessed and re-integrated according to any user-defined method, and is particularly useful when comparing successive sample chromatograms or chromatograms produced at long time intervals. General Laboratory Computer Operation of the system as a general-purpose laboratory computer for running programs written in BASIC, FORTRAN or PASCAL has effected a standardisation of calculation regimes and presentation of results. The interest and enthusiasm generated within the division has resulted in many programs being written, by members of ACD, for performing routine calculations, controlling instruments and reprocessing data.As an example, a relatively complex FORTRAN program, exten- sively used for the calculation of chromatographic data, produces a graphical plot for multi-level calibration pro- cedures. A simpler program, written in BASIC, runs from a22 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 method in autocall made to calculate the efficiency of capillary GC columns. Software written by the analyst allows a quicker throughput of data and enables analytical results to be reported in customer preferred formats. Another example is a program written in support of mass loss studies on pesticide slow release devices. This program enables time consuming calculations to be handled rapidly by the computer and presents the results in both tabular and graphical formats.Database Management IMAGE/QUERY is a database management software package for developing small, localised laboratory databases, for example, to record the condition and use of chromatographic columns. A database is currently being developed to store reference chromatograms and record the analyses of various products. This database will be used for: comparing successive batches of technical materials from production plants; recording the effects of different formulation adjuvants on chromatography; comparing analytical standards and reference materials. The setting up of databases is an area requiring further development. Currently, the feasibility of operating a total sample management system, involving an extensive and complex database, is being assessed.In summary, the laboratory automation system installed in ACD is rapidly proving an invaluable asset to the daily operation of the laboratory. The system has proved to be extremely reliable, especially in the areas of instrument control (unattended analyses) and data acquisition. In the present era, where cost effectiveness is paramount, the system has provided scope for time saving both through the unattended routines and by the ability to provide re-analysis of vital or complex data without having recourse to a repeat of the whole analytical process. User written programs in high level languages have enabled a consistent calculation and presentation of analytical data. The acquisition of data by a computer can be a meaningless exercise no more beneficial than that generated by an integrator or a manual measurement. The data should lead to information that is both usable and useful or even innovative or novel.This information should subsequently lead to know- ledge. A computer system should not just be a time saving device or an esoteric excursion into data manipulation, there must be real value and real advantage as the cost can be high when setting up such a system, not just in the purchase of hardware and software, but in the subsequent education and training of those who operate or manage the system. Ulti- mately, total sample management in combination with infor- mation storage and retrieval should lead to a state where the knowledge resides in the system and is readily accessible to all users.Laboratory automation systems which are flexible and easy to operate reduce the demands of routine analyses on the analyst's time and assist in method development and retrieval of data, thereby enhancing efficiency and reducing unit costs. I thank the Management and members of SRC's Analytical Chemistry Division for their assistance in preparing this paper. Studies on Surface Anion Exchangers for Ion Chromatographic Determinations S. J. Lyle and C. H. G. Pearson The Chemical Laboratory, University of Kent at Canterbury, Kent, CT2 7NH The work decribed has been carried out at the University of Kent at Canterbury in conjunction with the CEGB, whose interest is in monitoring the purity of boiler feed water in AGR Power Stations, as an accumulation of dissolved salts could result in serious corrosion of the boilers.Exploratory work has been carried out with the objective of developing new stationary phases for the separation of anions in ion chromatography. The main criteria to be used in selection of new materials were ease and reproducibility of preparation and stability under working conditions. In the preliminary work outlined here, some products based on PVC and polyacrylonitrile are considered as possible stationary phases. An ion chromatograph1 consists of two columns, a separator and a suppressor, connected in series, followed by a conductiv- ity detector. The most commonly used eluting medium is an aqueous mixture of sodium carbonate and sodium hydrogen carbonate. In the first column, separation results from the different affinities of the anions for the separator resin.The second column, the suppressor, has two functions; it suppresses the background conductivity and enhances that due to the species of interest. This is achieved by replacing cations with hydrogen ions. Thus, sparingly dissociated carbonic acid, of low conduc- tivity, is formed from the eluent, while the anion of interest, if it is the basic component of a strong acid, is completely dissociated and results in relatively high conductivity. Accord- ingly, there is a peak of conductivity, the magnitude of which is dependent on the mobility of the anion and of the associated hydrogen ion. The conventional ion-exchange resins cammonly used con- sist of beads of polystyrene cross-linked with divinylbenzene (DVB), forming a framework to which functional groups can be attached.In the instance of ,the suppressor a sulphonate group is attached, forming a cation exchanger, and for the separator, a quaternary ammonium group is attached to form an anion exchanger. Sulphonated form, cation exchanger Quaternized form, anion exchanger The separator should preferably be of very low ion-exchange capacity, where ion-exchange capacity is the number of exchangeable groups per unit dry mass or wet volume of resin. Exchange should be on, or as close as possible to, the surface of the bead. This is because diffusion processes within an ion-exchange bead are slow, reIative to mobile phase velocity, and rapid equilibrium between the ions on the resin and in the mobile phase is highly desirable to minirnise band spreading and unacceptabIy long elution times.The number, N , of samples that can be analysed before the suppressor bed requires regeneration is given by where V is the bed volume of capacity C, subscripts a and b refer to Suppressor and separator, respectively, and K q is rhe equilibrium constant for the exchange reaction RY + X- e RX + Y- in which R+ is the resin framework, X- the ion to be determined and Y- the displacing ion in the eluting solution. In N = V,C,/(V,C,K$)ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 23 practice V , = Vb and N is then dependent on the ratio of the column capacities and K$. Commercially, two types of separator are available. There is the surface agglomerated type, used in Dionex equipment [Dionex (UK) Ltd., Farnborough, Hampshire], in which fine particles of conventional strong base anion exchanger are coated on the surface of surface sulphonated polystyrene- based exchangers, where they are held by strong electrostatic forces.Alternatively, there is the type consisting of silica beads with chemically bonded hydrocarbons carrying quaternary ammonium groups bound to the surface. Both these types of exchanger are expensive, and lack long-term stability. Determination of Ion Exchange Capacity The measurement of ion exchange capacity was based on the displacement of chloride by nitrate and the subsequent determination of the former ion. A convenient method for this purpose is turbidimetry ,2 which is based on the turbidity of colloidal silver chloride.This method allows determinations of sufficiently low concentra- tions of chloride ions, and can be carried out reproducibly in a medium of 50% aqueous ethylene glycol which maintains an even and consistent particle size. Attenuation of the light intensity by the sample is measured as an absorbance equi- valence which is linear with chloride concentration, enabling determinations between 2 and 10mmoldm-3 to be con- veniently executed. The capacity of commercial strong base exchangers is in the region of 4rnequivg-1, whereas that of surface anion exchangers is generally within the range 0.010-0.001 mequiv g-I. Polyvinyl Chloride Surface reactions replacing a chlorine atom with a quaternary ammonium group have been investigated.Cross-linked poly- mer could not be obtained commercially, but it was hoped that by careful solvent selection and reaction times. essentially surface reactions only would take place, and consequently on column the aqueous eluent would not penetrate very deeply into the particles. The reactions were as follows: (a) conversion of ethanolamine to the monosodium salt, NR2(CH2CH20H3 + Na-+ NaOCH2CH2NR2 + $H2 (1) ( b ) bonding of tertiary amine to PVC >C-Cl+ NaOCH2CH2NR2 + sC-O-CH2CH2NR2 + NaCl (2) (c) quaternization to form the required exchange group ZC-O-CH2CHZNR2 + CH3I + * SC-O-CH2CH2NR2CH21- (3) where R = CH3 or HOCH2CH2. Unfortunately, although polymers of capacities betwehn 0.005 and 0.460 mequiv g-1 were prepared, this functionaliza- tion makes the polymer chains themselves soluble in aqueous media.Therefore no separations were obtained. On a column, the functionalized polymer and the sample were eluted without retention. Polyacrylonitrile The work using PVC shows that cross-linkage is an essential feature of a stationary phase. Bearing this in mind, poly- acrylonitrile, cross-linked with DVB ,3 was prepared by suspen- sion polymerization. The resin that was prepared had about 8% cross-linkage. Surface cyano groups were reduced (equa- tion 4) by using sodium bis(2-methoxyethoxy)aluminium (4) hydride (“Red-al,” Aldrich Chemical Co. Ltd., Gillingham, Dorset) to produce the corresponding primary amine, which was subsequently methylated, with the object of conversion to quaternary ammonium groups (equation 5 ) .CH2-NH2 + 3Mel+ CH2iMe, + 2HI . . (5) However, this methylation reaction sequence is probably complicated, and possibly retarded, by the formation of intermediate amine salts. The ion-exchange capacity of par- tially reacted product will therefore be pH dependent, as each amine will possess a different pK value [equations (6)-(8)]. CH2NHMe + H+ c CH2NH2Me . . . . (7) @-CH2NMe2 + H+ ,& @CH2NHble2 . . . . (8) Resins with ion-exchange capacities of 0.007-U.053 mequiv g-1 have been prepared where the capacity refers to all of the protonated amine and the quaternary ammonium groups. Separations of chloride and sulphate have been obtained using such exchangers and elution at pH 8.0, with an aqueous mixture of sodium carbonate and sodium hydrogen carbonate as the eluent.These are much faster than similar separations using a Dionex column, and use a much more dilute eluent, which has the advantage of protecting the suppressor column. This suggests that the functionalized polyacrylonitrile shows promise as a surface exchanger in a separator column. However, studies on column efficiency with common operating conditions of flow-rate and eluting medium are required for proper comparative purposes and have yet to be performed. Conclusion The work on PVC indicates that cross-linking is an essential element in the support of functional groups. A resin is therefore better than a plastic material as a substrate. This is borne out by the work using cross-linked polyacrylonitrile, which suggests that this approach can lead to a satisfactory anion exchanger for separator columns in ion chromatography.Unfortunately, it is a weakness of these quaternary ammonium exchangers that, with time, they undergo reactions leading to the loss of a quaternary ammonium functional group, It may, however, be possible to reactivate such a batch of resin by further treatment with Red-a1 and methyl iodide. References Small, H., Stevens, T. S . , and Baumann. W. C., Anal. Chern., 1975, 47, 1801. Puphal, K. W . , Booman, G. L., and Rein, J . E., United States Atomic Energy Commission Research and Development Report No. IDO-14389. November 28, 1956. Vernon, F., and Eccles, H., Anal. Chirn. Acta, 1976, 82, 369.24 ANALYTICAL PROCEEDINGS. JANlJARY 1985, VOL 22 Aspects of the Direct and Indirect Determination of Selected Metals in Water by Electron Spin Resonance Spectroscopy D.Thorburn Burns, 6. G. Dalgarno and 6. D. Flockhart Department of Pure and Applied Chemistry, The Queen's University of Belfast, Belfast, BT9 5AG, Northern Ireland A direct method has been developed for the determination of total iron in aqueous solutions containing Mn(II), Fe(I1) and Fe(II1). The spectrum [Fig. l(a)] from the initial solution corresponds to that from the hydrated Mn(I1) ion and is a characteristic six-line signal due to hyperfine interaction with the 55Mn nucleus, which has a spin of 5/2. In comparison with other metal ions in aqueous solution, this is a relatively intense signal, and is ideal for quantitative work. Peak to peak amplitudes in the first derivative spectra can therefore be used for Mn(I1) determinations.The analytical range is 10-6- M . Fig. 1. E.s.r. spectra (first deviation): (a), Mn(I1) and Fe(II1) (both 1 0 - 3 ~ ) in water; ( b ) , after addition of NH,F; (c), after oxidation of Mn(I1) In contrast to Mn(II), the hydrated Fe(1II) ion gives a single broad resonance line, the width exceeding 1000 G. Conse- quently, the intensity is very low and the spectrum undetect- able at low concentrations. However, peak width is affected by the particular ligand field present. Thus, the addition of fluoride ion results in an intense spectrum from [FeF6]-7-. This narrow, well-resolved signal is due to the considerably longer relaxation time for [FeF6]3- compared with that for the hydrated Fe(II1) ion. Overlap between the Mn(1I) and the [FeF6]3- spectra makes quantitative measurement difficult [Fig.l(b)]. When Mn(I1) is oxidised with periodate the Mn(I1) interference is eliminated and the [FeF6]-7- signal can be measured accurately [Fig. l(c)]. There are seven component lines in the spectrum due to fluorine ( I = Y2) hyperfine interaction. In the presence of fluoride ions, Fe(I1) is oxidised to Fe(II1) and hence the procedure measures total iron, the range being 10-6-10-2 M . The oxidation of Fe(I1) can be followed in an e.s.r. redox titration with dichromate. The Cr(II1) signal is measured continuously at the top of the derivative curve by maintaining a fixed magnetic field. Location of the end-points can be established with a precision of 0.4% , based on 6 replicates. The solutions are circulated through the e.s.r.cell by use of a peristaltic pump. An indirect method has been developed for the determina- tion of Zn(I1) using a serniquinone spin label. Stegmann et al. * have shown that Zn(1I) can be complexed with 3.6-di-fert- butyl-2-(2-h~droxybenzylideneamino)hydroquinone in the presence of pyridine. If the chelate is then extracted into benzene and oxidised, the resulting paramagnetic complex gives a sharp e.s.r. signal. The preparation of the Schiff base ligand involves a multi-stage synthesis, starting with dibutyl- hydroquinone.2 The tetrahedral coordination of the Zn(T1) involves the bidentate Schiff base and two pyridine ligands to give a four-coordinate mixed-ligand complex. Oxidation of the hydroquinone group of the complex by atmospheric oxygen gives the semiquinone anion-radical whose structure is shown in Fig. 2(a).The structure is depicted as flat and the two pyridine molecules have been omitted for clarity. Fig. 2(b) shows the e.s.r. spectrum (g = 2.0046) of the radical. The unpaired electron is in a m-molecular orbital that extends over the semiquinone ring, hyperfine splitting by the proton in this ring accounting for the doublet. As the zinc does not adopt a 4 G - Fig. 2. ( a ) Structure and ( h ) e.s.r. spectrum of the oxidized zinc chelateANALYTICAL PROCEEDINGS, JANUARY 19x5, VOL 22 25 coplanar geometry, the semiquinone oxygen is not involved in the co-ordination. The semiquinone ring is approximately perpendicular to the six-membered chelate ring, and this relieves any steric hindrance with the 3-terr-butyl group.It also follows that any Jc-overlap between the semiquinone ring and the nitrogen will be negligible, and so no hyperfine splitting by the I4N nucleus or by the four protons in the other benzene ring is to be expected. The extraction and instrumental variables were examined in sequence. The e.s.r. signal intensity showed a strong depen- dence on pyridine concentration up to an optimum concentra- tion of 5 ml of pyridine per 100 ml of aqueous phase. The radical concentration reached a maximum value about 1 h after the solvent extraction step and then declined slowly. A I-h interval between extracting the chelate into the benzene phase and recording the spectrum was therefore adopted in order to obtain maximum signal and reproducibility. Optimization of the instrumental variables involved examining the effects of the modulation amplitude and microwave power on the signal intensity .The method is straightforward. Although the semiquinone anion-radical is generated by atmospheric oxidation, the free ligand gives no e.s.r. signal under these conditions. Common toxic metals, such as cadmium and lead, do not interfere. The method also offers advantages over techniques involving nitroxide labelled complexing agents.3 The spectra of the resulting metal chelate and the free nitroxide labelled ligand frequently coincide, thus necessitating a preliminary chemical separation. Quantitative determinations of Zn(I1) by the present method are based on the linear relationship between the peak-to-peak amplitude of the derivative signal and the initial concentration of the metal ion.The calibration graph was linear over the range 10-6-10-3 M Zn(T1) with a detection limit of 5.5 x 10-7 M Zn(I1). Taking seven replicate analyses at the 2.5 x 10-5 M level, the precision was 2.4%. References 1. 2. 3 . Stegmann, H . B., Schnabel, M . , and Scheffler, K.. Angew. Chem. Int. Ed. Engl., 1979, 18, 943. Stegmann, H. B., personal communication. Nagy, V. Yu., Trends A n d . Chem., 1983. 2. 136. Analysis of ionic Species by HPLC Marcus H. Gaffney and Michael Cooke School of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1 TS Ion chromatography is an extremely useful technique, which has applications in many fields. Interest in the subject has intensified recently, which is directly attributable to the relative ease with which ion chromatography can be performed using standard isocratic HPLC equipment.The analysis of strongly ultraviolet absorbing ions is relatively simple but the analysis of weak ultraviolet absorbing species and non- absorbing species has presented many problems to the ion chromatographer, particularly with regard to detection at trace levels. The advent of indirect ultraviolet (UV) derection has allowed us to overcome many of these problems. Conventional UV detection Flow Stationary Phases Firstly, the choice of stationary phase for ion chromatography must be considered. There are both silica based and resin based packing materials available. The former type was selected because of their resistance to pressure, having noted their pH limitation (working range pH 2-8).There are two major types of silica based packings of use to the ion chromatographer: fixed site ion exchange materials, which consist of positive or negative sites bonded on to the silica surface (examples of this type of phase include Partisill0 SAX and Partisil 10 SCX); and Absorbance Transmittance Eluant gives increase in absorbance Sample absorbance > eluent absorbance 0% L ’ 100% Positive peaks Indirect UV detection Flow cell Absorbance Transmittance Eluant gives decrease in absorbance Eluent absorbance > sample absorbance 0% ’ ‘ 100% Negative peaks Fig. 1. Representation of conventional and indirect ultraviolet detection26 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 octadecylsilane (ODS) phases, which can also be used as dynamic ion exchangers if modified with a suitable counter ion.1-3 Modified ODS phases are generally of low but variable capacity, depending on the conditions employed.Factors affecting the capacity of ODS columns include the type of ODS used, the chain length of the alkyl group on the modifying ion, the organic content of the mobile phase and its pH. Low capacity column materials (e.g. ODs, Partisil 10 SAX and Vydac 302IC) were favoured for this work because of the demands of our detection technique. Detectors There is a choice of detectors available for ion chromato- graphy. A conductivity detector is moderately sensitive, but one’s choice of counter ion is limited and the detector is subject to temperature effects, A refractive index detector is very insensitive and is also subject to temperature effects.The ultraviolet detector is sometimes useful at low wavelengths, e.g., 210 nm, for ions such as NO,, but it is not universally applicable. 1 Indirect ultraviolet detection possesses many advantages over these other detection techniques. It enables ions to be chromatographed quickly with high efficiency and high sensitivity (e.g., sub-nanogram levels of C1- are detect- able). Many ions can be determined simultaneously with interferences due to the chromatographic separation avoided. Indirect UV is a universal detection method, exhibiting no selectivity, and it is widely applicable. The method is quanti- tative simply by construction of a calibration curve from standards, and the technique does not require expensive dedicated hardware.4.5 Indirect UV Detection Indirect UV detection is a very simple concept, the basic mechanism of which is demonstrated in Fig.1. In conventional UV detection an eluent is used which has a low absorbance at the monitoring wavelength. This produces a steady base line at low absorbance. When a UV absorbing species enters the flow cell an increase in absorbance results, which gives rise to a positive peak. However, in indirect UV detection an eluent is used that absorbs strongly at the monitoring wavelength. For anions this is commonly phthalate, which produces a steady base line at high absorbanee. When a non-UV absorbing or weakly UV absorbing species enters the flow cell a decrease in absorbance results, which gives rise to a negative peak.Generally, the polarity of the recorder is reversed by reversing the leads to the input terminals in order to produce a more conventional chromatogram. The choice of monitoring wavelength for indirect UV detection is not critical. Generally, a wavelength is selected that combines maximum sensitivity with a convenient back-off, which is usually between 7 and 11 on our instrument. For phthalate a wavelength between 260 and 300nm is rec- ommended. The mechanism of separation and detection of anions using phthalate for indirect UV detection is well understood. Firstly, if an ODS column is to be used, the surface is loaded with a quaternary ammonium salt, which equilibrates to form a dynamic ion exchanger. This stage is unnecessary for fixed site ion exchangers because the ion sites are an integral part of the column.Secondly, potassium hydrogen phthalate is then incorporated into the eluent. Ion pairs are formed with the quaternary ammonium ions until all potential sites in the column are occupied. Subsequently, a constant level of phthalate elutes from the column, so providing a steady base line. When sample ions are introduced they displace phthalate at the top of the column. This phthalate passes down the column because there are no remaining sites for it to absorb on to and it elutes at the solvent front. As more phthalate enters the column the sample ions are displaced. Because different ions have different affinities for the column surface they pass down the column at different rates and hence are separated.Finally, on emerging from the column and entering the flow cell the separated sample components are detected as outlined previously. To date this detection technique has been applied to anion analysis mainly because many well-established techniques already exist for the determination of cations, viz., atomic- absorption and atomic-emission spectrophotometries, elec- troanalytical techniques and ion-selective electrodes. Experi- ments currently under way have demonstrated that ion chromatography with indirect UV detection works equally well for cation analysis when an appropriate UV absorbing counter ion (e.g., pyridinium) and an appropriate column (e.g., ODS modified with pentadecafluorooctanoic acid) are employed. Applications Ion chromatography with indirect UV detection has many applications in the fields of environmental monitoring, industry, agriculture, food science and medicine, This research project has concentrated primarily on environmental, food and medicinal applications.Samples such as tap water, pond water ahd river water were chromatographed and separations of species such as phosp- hate, CI-, NO, and SO!- were achieved. The ability to determine this range of species in water both rapidly and quantitatively in a single analysis is highly significant, particul- arly following the recent concern over the effects of acid rain. Samples of Worcester sauce and tomato sauce were chro- matographed, after dilution with de-ionised water, and traces were obtained in which species such as acetate, C1- and NO?, were separated and could be quantified.Organic acids were separated in samples of cider and beer and organic acids, together with C1- and NO,, have been separated in samples of blood, sweat and tears. In Bristol we have a particular interest in measuring levels of small organic acids, such as lactate and pyruvate, routinely in humans. This has great significance in diabetes management, in the diagnosis of lactic acidoses and in monitoring the shock - stress response. The acids originate as by-products from a metabolic pathway known as the Krebs cycle. Acid levels in 4 + 5 3 I 1 1 1 1 2 4 6 8 Ti meim i n Fig. 2. HPLC of standards and serum extract. Parameters: column, Partisil 10 SAX (30cm x i.Srnrn, dp = 10pm); eluent, 1 0 - ’ ~ potassium hydrogen phthalate solution; flow-rate, 0.5 ml min 1 ; sensi- tivity, 0.08 a.u,f.s. into 10 mV f . s . d , ; detection. 296nm (indirect UV). Samples: ( a ) , 20 pl aqueous mixture of standards (2-5. 100 pg ml- I and 6, 20 pg ml- 1); (b), 20 p1 serum extract, Peak identification: 1, acetate; 2, 3-hydroxybutyrate; 3, lactate; 4, pyruvate; 5 , acetoacetate; 6, chlotide; and 9 , nitrateANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 27 serum reflect the metabolic efficiency and condition of the body. The normal levels of acids in serum fall in the pgml-1 range. In diagnosis one is looking for exaggerated levels caused by gross changes in metabolism. A suitable separation of standards was achieved by using a Partisil 10 SAX column and 10-3 M phthalate for indirect UV detection [Fig. 2(a)], Follow- ing a simple sample clean-up through an Ag+-loaded anion- exchange cartridge to remove C1- (the major potential interferent), serum extract was chromatographed [Fig. 2(b)]. Lactate and pyruvate were successfully separated and quanti- fied at low levels in serum, thus enhancing our ability to recognise and diagnose the aforementioned conditions. Conclusions The development of indirect UV detection and its application to problems in ion chromatography has enabled us to analyse UV-inactive species at trace levels that were previously difficult to determine. Little sample preparation is required prior to analysis, the sensitivity is high and there is little selectivity. The technique is very simple and flexible and will lend itself well to automation. We thank Pye Unicam Ltd., Cambridge, for supporting this work. References 1. 2. 3. 4. 5 . 6. Reeve, R. N.. J. Chromatogr., 1979, 177, 393. Skelly, N. E., Anal. Chem., 1982, 54, 712. Cassidy, R. M., and Elchuk, S., J. Chromatogr. Sci., 1983, 21, 454. Small, H., and Miller, T. E., Anal. Chem., 1982, 54, 462. Cochrane, R. A., and Hillman, D. E., J. Chromatogr., 1982, 241, 392. Cooke, M., J. High Resolut. Chromatogr. Chromatogr. Com- mun., 1983, 6 , 383. RSC ANALYTICAL DIVISION The Annual Meeting on R AND D TOPICS IN ANALYTICAL CHEMISTRY will be held at The Queen's University of Belfast on June 27th and 28th' 1985 Papers are invited describing work carried out by postgraduate research students in Universities and Colleges and by young research workers in industrial and other establishments. Contributions are to be presented by the student or his industrial counterpart in a 20-minute lecture. There will also be a poster session in which work can be exhibited and discussed. Titles of oral papers or posters with the name(s) of the author(s) and a summary of 100-150 words should be sent by February 28th to the Secretary, Analytical Division, Royal Society of Chemistry, Burlington House, London WIV OBN.

ISSN:0144-557X    

DOI:10.1039/AP9852200015

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

28 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 I tquipment News Mass Spectrometer The PlasmaQuad inductively coupled plasma source instrument offers detection limits as low as tens of parts per trillion and allows the entire periodic table to be scanned in milliseconds. The low detec- tion limits are particularly relevant for environmentally important elements such as mercury, cadmium, lead and uranium. Isotope ratios can be measured directly and isotope dilution analysis gives ex- tremely accurate results. VG Isotopes Ltd., Ion Path, Road Three, Winsford, Cheshire, CW7 3BX. Spectrophotometer Graphics A Lambda 5 graphics update kit is avail- able for existing Lambda 5 ultraviolet - visible spectrophotometers. As many as six full range (190-900 nm) spectral files can be stored and can be viewed on the screen or copied on the instrument’s plotter. Subtraction and addition of spec- tra or multiplication by a factor can be performed. First to fourth derivative spectra can be calculated and displayed from percentage transmittance and ab- sorbance data stored in the memory.The graphics feature is compatible with the six cell programmer so that repetitive scans can be displayed for comparison before the information is copied on to the printer - plotter. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire, HP9 1QA. Microanalysis The Edax 9900 is a microanalytical system from Edax International (Prairie View, IL, USA), available from Philips, based on an energy-dispersive X-ray spectro- meter. The system is designed for use with electron microscopes (SEMs or STEMS), and can collect, process, display and store a variety of signals: backscattered or secondary electrons, absorbed electron current, cathode luminescence, EDS and WDS elemental X-ray and electron energy loss spectrometry signals.Process- ing functions include signal thresholding, signal ratioing, background subtraction and deadtime correction, with advanced colour graphics. The system provides full quantitative analysis from boron to uranium. Philips Scientific and Industrial Equip- ment, 5600 Eindhoven, The Netherlands. X-Ray Spectrometers The PW 1606 simultaneous XRF spec- trometer from Philips has a 3 kW, 60 kV generator that cuts power requirements by 40% and no special cooling circuit is required. High-speed measurement of up to 28 elements is possible, and new hardware and software features combine to give a reliable system for process control, e.g., in the cement, metals, glass and mining industries.The PW 1404 sequential XRF spec- trometer has multilayer “crystals” giving enhanced sensitivity to light elements down to C and B. Side-window X-ray tubes are used, with a new dual-anode tube that allows the use of a single X-ray source. New generation software pro- vides qualitative and quantitative capa- bilities, including colour graphics. Philips Scientific and Industrial Equip- ment, 5600 Eindhoven, The Netherlands. X-ray Spectrometer Improvements Replacement of the conventional TIAP crystal with PX-1 gives improved light- element performance in the makers’ PW 1400 sequential X-ray spectrometer. Called a multilayer, PX-1 is created by the deposition of alternate layers, only nano- metres thick, of heavy and light element atoms on a silicon substrate to form a crystal-like structure that acts as an X-ray monochromator. Advantages include long-term stability, non-toxicity and reduced higher order reflections.Another development is a carbon analy- sis accessory, which includes a special monochromator and which can be attached with only minor optical and electronic modifications. The carbon analysis attachment gives an improve- ment in sensitivity of five to ten times that obtained with a normal lead stearate crystal; this is achieved using only a standard argon - methane counting gas. Pye Unicam Ltd., York Street, Cam- bridge, CB1 2PX.Chromatography Detector Data System The PU 4850 data station, complete with specially written software, is for use with the makers’ PU 4021 multi-channel ultra- violet LC detector. It allows hundreds of spectra to be stored in a single chromato- graphic run. There are two modes of operation. The chromascan mode enables storage of complete ultraviolet or visible spectra at a programmable rate to a maximum of Is-’. The on-line VDU displays the results as a three-dimensional view of the sample and this can be displayed from a number of different viewpoints, ensuring that no data are hidden. The second mode involves selec- tive storage of spectra from a chromato- graphic run. Parameters can be set to enable a spectrum to be acquired at peak apex, at inflection points, at a pre-set retention time, or manually at any time.These peak detection algorithms can be run concurrently, providing data for peak authentication and for monitoring peak purity . Pye Unicam Ltd., York Street, Cam- bridge, CB1 2PX. Graphite Tube for Atomic- absorption Spectroscopy The TPC (Totally Pyrolytic Cuvette) is made completely from pyrolytic carbon and achieves the prime requirements of low porosity and low carbide formation, giving a longer analytical lifetime than existing tubes. An example of its per- formance is in results for manganese, where the TPC can still be used after 2200 firings without any significant loss in performance, whereas a pyrocoated tube lasts approximately 800 firings before performance deteriorates. Pye Unicam Ltd., York Street, Cam- bridge, CB1 2PX.Gas Chromatograph The HNU GC 421 features multi-ramp temperature programming and offers the choice of FID, PID and far UV detectors. A dual-column instrument, it accepts any combination of packed or capillary col- umns and it can incorporate up to three integrated detectors; these are easily demounted to add auxiliary detectors. Other features include an on-column injection system for packed columns, a three-position universal detector base, an 1100-in3 dual-column oven, an autozero facility and an STD bus, which simplifies the addition of accessories. Analysis Automation, Southfield House, Eynsham, Oxford, OX8 1JD. Gas Chromatograph The PU 4550 high-resolution separation station can be used either as a stand-alone or connected to an existing data system or video chromatography control unit.Dual packed-column injectors are provided and can easily be replaced by one of three capillary injectors. A Grob-type splitless injector and inlet splitter are available for use in automatic operation. A range of five detector types, all suitable for use with capillary columns, is available and the oven accepts two detectors simul- taneously. Pye Unicam Ltd., York Street, Cam- bridge, CB1 2PX.ANALYTICAL PROCEEDINGS, JANUARY 1985. VOL 22 29 Gas Chromatograph The PU 4900 is designed for both capillary and conventional use and has been opti- mised for capillary columns and new capillary injectors. The column oven, with a slide-out assembly for easy access, has an aerodynamic air flow path to ensure that the column is in a thermally stable zone with minimum gradients, so that repeatability is achieved without peak distortion or splitting.Also, the controlling resistance thermometer is next to the column, resulting in an excep- tionally low thermal lever, minimising the effect of ambient temperature. For multi-dimensional chromatography there is a unique “mirror image” satellite oven with simultaneous but independent control and the sample can be transferred directly from one to the other. A plug-in interface oven with independent control eliminates loss of sample or resolution. Other features are comprehensive gas control, with up to six pressure regulators and twelve solenoid valves, automatic operation from sample injection to calcu- lation of results, multiple detector opera- tion with up to three detector systems operating simultaneously with full data handling facilities for each channel, a graphics capability via an integral display unit and data storage using two floppy disks.Pye Unicam Ltd., York Street, Cam- bridge, CB1 2PX. Gas Chromatographs Nine “routine B” versions of the Model 8300 instrument are announced. The 8300B series are configured for one detec- tor only. FID, ECD and NPD packed and capillary versions are available; full screen graphics and data handling facili- ties are optional accessories. Single col- umn temperature programming using automated bleed compensation is stan- dard. The 8300B instruments are compat- ible with the same range of accessories as the Model 8300; these include the AS- 8300 autosampler, the HS-6 headspace sampler and the ATD 50 automatic thermal desorption system.Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire, HP9 1QA. Gas-chromatographic Analysis of Organophosphorus Compounds It has been shown that the makers’ nitrogen detector, based on alkali flame ionisation principles and using an RbCl salt tip, can be used without modification for the analysis of organophosphorus compounds. By means of a simple opti- misation procedure a detectability of 2 x lo-lsgs-1 of phosphorus can be obtained. Pye Unicam Ltd., York Street, Cam- bridge, CB1 2PX. Hydrogen Safety System The system monitors the actual hydrogen concentration in gas chromatographs and takes the required precautions if the concentration becomes a fraction of the explosive limit.The concentration at Oxygen Analysers A range of on-line and portable trace oxygen analysers is announced. They monitor trace oxygen concentration to less than 1 p.p.m. and feature an electro- chemical transducer that requires no Chrompack hydrogen monitor which gas flow and oven heating are switched off can be set by the operator. The main parts in the safety system are continuously checked for faults by an electronic circuit. Chrompack UK Ltd., Unit 4, Indescon Court, Millharbour, London, E l 4 9TN. HPLC Pump The Model 114M features “on-demand” u-flow capability. Flow-rates are avail- able from 0.001 to 0.999mlmin-1, ad- justable in increments of 0.001 ml min-1. The Model 114M is compatible with all the makers’ Series 340 systems and it features a long-lasting seal and digitally selectable upper and lower pressure limits.A battery back-up to prevent parameter loss in case of power failure is standard. Beckman-RIIC Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buckinghamshire. Software for Low-angle, Laser-light Scattering Detection The Model 3950 LALLS package per- forms relative molecular mass calcula- tions based on LALLS detectors in size- exclusion chromatography instruments. It is designed for the makers’ Series 4400 desk-top chromatography data system, which is based on the HP 9000 Series 200 computer. It operates in conjunction with the makers’ standard chromatography software and optional gel-permeation chromatography software. The package features a graphics routine that allows the operator to change base lines and process times graphically by using the system’s cathode-ray tube display for immediate recalculation of results, a curve smooth- ing routine to handle poor signal to noise readings and the capability to handle measurements of up to 10000 area slices for each run.Nelson Analytical, Inc., 10061 Bubb Road, Cupertino, California 95014, USA. maintenance and is simply discarded at the end of its useful life. The BT 2000 Series are mains powered and are suitable for on-line applications. The BT 200 Series are powered by a rechargeable battery supply. Bedfont Technical Instruments Ltd., P.O. Box 42, Streatham, London, SW16 1JH. Multi-component Across-stack Ana- lyser The TPA 330 makes possible the monitor- ing of flue gases for all the constituents which cause acid rain.Based on a multi- wavelength single beam principle, it is capable of measuring simultaneously up to three gas components, e . g . , CO, C 0 2 and S02, or H20, SO2 and CO, or methane and nitrogen oxides together. Telsec Process Analysers Ltd., 34 Tresham Road, Orton Southgate, Peter- borough, PE2 OSE. Gas Analysis Systems A range of systems specifically for use in the biotechnology field is announced. Capable of analysing a wide range of gases including carbon dioxide, methane and oxygen, the units are suitable for fermentation processes of all types. Sup- plied as standard or made to meet indivi- dual requirements, the systems can be used to monitor one process singly or several processes simultaneously or sequentially.A software and hardware back-up is supplied. Leybold-Heraeus Ltd., 16 Endeavour Way, Durnsford, London, SWlG 8UH. Portable pH Meter The pHI31 is a bench-top model aimed at quality control, environmental, research and industrial laboratories. It provides a digital display of result, error and out of temperature indication and a universal language keyboard. It continuously dis- plays temperature and carries out temper- ature computation with or without an30 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 automatic temperature compensation probe. It also features slope indication and computation, automatic standardisa- tion, stability detection, calibration and recognition of five buffers. Beckman-RIIC Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buckinghamshire .Liquid Chromatograph Philips have introduced the PU 4003 low-dispersion gradient chromatograph, catering for flow-rates down to 10 p1 min-1 for Microbore columns and up to 10mlmin-1 for conventional col- umns and FAST LC. The cell for Micro- between pH 0 and 14 and redox potentials in the range &1999mV, and features manual temperature compensation. With a 12mm high liquid crystal display and robust plastic case, it is intended for survey and field work and as a back-up to on-line process monitoring and on-site quality control checks. Pye Unicam Ltd., York Street, Cam- bridge, CB1 2PX. Conductivity Meters The PW 9527 from Philips is a microprocessor-controlled conductivity meter with keyboard parameter entry, measuring over the complete range from Philips PU 4003 liquid chromatograph bore LC has a volume of l y l and that optimised for FAST LC can contain 2 .4 ~ 1 . Also offered are a standard 8-pl type and a larger preparative flow cell. The detector response time is 0.1 s. Pye Unicam Ltd., York Street, Cam- bridge, CB12PX. Multi-function Instruments A range of instruments is announced. Built around microcomputers, they can be interfaced with larger computers if required. The range includes the Research Machines RM103, which com- bines the functions of a digital voltmeter, frequency meter, counter, transient recorder and data logger, as well as being programmable for such uses as a light meter, a flow-meter, etc. The Computer- scope is a digital storage oscilloscope, but additional software provides signal averaging, spectrum analysis, function generation, waveform comparison and analysis and histogram analysis. The anal- ogic D6000 universal waveform analyser offers both high speed ADCs (100 MHz) and high resolution ADCs (14 bits).Advanced Instrumentation and Measurement Systems Ltd., Boundary House, 400 Woodstock Road, Oxford, OX2 8JW. Portable pH meter Philips new PW 9419//10 hand-held pH and mV meter allows rapid calibration in field conditions, reads to 0.01 unit pure water to concentrated acids, alkalis and salts. Features include autoranging and a 4-digit LED display. An RS 232C serial output provides a digital signal for actuating a printer or connecting to a microcomputer. The PW 9526 is intended for routine measurements, with liquid crystal display of conductivity in the range 0-200 mS cm-1.A cell constant from 0.02 to 1.5 cm-1 can be used and temperature coefficients from 1 to 4% K-1 accommo- dated. The meter is autoranging and employs a direct measurement mode with automatic and manual temperature com- pensation. The PW 9525 is a battery-operated hand-held model with a liquid crystal display. Pye Unicam Ltd., York Street, Cam- bridge, CB1 2PX. Thermal Analysis Software Two programs for thermogravimetric analysis, designed to run on the makers’ thermal analysis data station (TADS), are announced. They are the thermographic (TG) program mode, which allows com- positional analysis of filled polymers, rubbers and coal to be optimised for maximum sample throughput, and the thermogravime tric decomposition kine t- ics software, which predicts the lifetime stability of polymers, filled systems and organic materials.Beaconsfield, Buckinghamshire, HP9 1QA. Liquid Scintillation Counter The LS 1801 is a bench-top counter. A three-channel system, it features a rack sample changer that will accommodate either standard vials (336 samples) or miniature vials (648 samples). Also featured is the Horrocks number method of quench monitoring; one quench curve will provide accurate results, regardless of the volume of sample, type of vial or choice of cocktail. It is possible to carry out microvolume counting with a sample or cocktail volume as low as 200 pi. There is a full alphanumeric control keypad. A multi-user capability provides 10 user files for storing customised programs, com- mand card programming with positive sample identification and a unique inter- rupt mode.Beckman-RIIC Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buckinghamshire. Ultracentrifuge The TLlOO is a bench-top model designed for ultracentrifugation of samples from 0.2 to 2.2ml. It generates forces of up to 436 000 g at 100 000 rev min-1. Five rotors are available. The makers provide poly- carbonate, polyallomer, cellulose pro- pionate and Ultra-Clear tubes for the rotors, and their Quick-Seal tubes can be used in the TLA-100.2 fixed angle and the TLV-100 vertical tube rotors. Beckman-RIIC Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buckinghamshire. Syringes The 1800 Series gas - liquid tight syringes feature an extended handle, which makes them easy to hold, and the relatively heavy metal plunger stem acts as a sup- port and guide to protect the small plunger against bending.Accuracy and precision are better than & 1% and capac- ities are available between 10 and 250 pl. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crecent, London, SW18 2LS. Balances The Shimadzu “standard” EB series elec- tronic balances feature automatic stability detection, through a choice of four time averaging bands, automatic zeroing, the facility to hold a stabilised value even after the sample has been removed from the pan, and data output for connection to the EP 40 printer or an RS232-C buffer unit. The “multifunction” balances feature, in addition, automatic memory, piece counting and percentage functions, a facility for specific gravity measure- ments and five statistical functions.The EP40-20 printer prints out measured data, lot number and sample number , and it can multiply any measured value by a select- Perkin-Elmer Ltd., Post Office Lane, able constant.31 V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London, SW18 2LS. Floppy Disc Option for Computing Integrator A floppy disc option is available for the CI-10 computing integrator, giving up to 2 Mbytes of fast access storage and exten- ded capabilities. It allows storage of a series of chromatographic runs. All files resident in the CI-10’s internal memory can be saved. Slices files can be saved “on the fly.” Chromatographic data can be later reprocessed direct from the disc. Laboratory Data Control (UK) Ltd., Milton Roy House, High Street, Stone, Staffordshire, ST15 8AR. Weighing Systems Siwarex Z is a compact system for manual or automatic operation installed in a desk cabinet.It has one output interface to which can be connected a thermal printer or an on-line level indicator. Siwarex ZM is also a modular system designed for manual or automatic operation and is in a 19in bench housing, but it can also be installed in a cabinet. It can be used with various interface modules linked to the central unit via a data bus. Both systems have a waterproof keyboard for the input of production and system data and control commands for adjustment and balancing. Siemens Ltd., Siemens House, Wind- mill Road, Sunbury-on-Thames, Mid- dlesex, TW16 7HS. Applicator Pipette Available in nine models from 2 to 10 pl, the MLA is ideally suited to situations where very small samples are required, such as counterimmunoelectrophoresis, thin-layer chromatography and immuno- diffusion.Features include de-tipping, colour coding and calibration adjustment. Shandon Southern Products Ltd., Chadwick Road, Astmoor, Runcorn, Cheshire, WA7 1PR. Mutagenicity Testing Mutascreen, developed bv Labsystems ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 Oy of Helsinki, is an ktomatic, computer ground correction. supported procedure for the testing of mutagenic and potentially carcinogenic characteristics of chemicals and other substances. Chemicals can be tested in a wide variety of concentrations with differ- ent bacterial strains, and the studies can be rapidly repeated. The growth of the bacterial strains is measured turbidime- trically and the results are given as growth curves and as alphanumeric data, showing all the necessary parameters of bacterial growth including inhibition, prolongation and the presence and number of rever- tauts.Labsystems (UK) Ltd., 12 Redford Way, Uxbridge, Middlesex, UB8 1SZ. Serial Communication Interface Adaptor The adaptor (SCIA) has been introduced for use with the makers’ Opus 70 single zone temperature controller, the Opus 72 single zone process controller and the Octet 8 zone temperature process con- troller. It allows communication with external computers, intelligent loggers and peripherals by adapting, where neces- sary: interface standard (RS232/RS422); Baud rate; data protocol; and number of stop - start bits and parity type.Gulton Ltd., The Hyde, Brighton, Sus- sex, BN2 4JU. Optical Emission Spectrometers Philips have launched the PV 8050 Series for simultaneous measurement of up to 56 elements in the range 165-485nm. An additional monochromator allows longer wavelength lines to be used, e.g., for Al and ICP work. A rigid exit slit plate carries selected slits for given applica- tions, and light guides eliminate cross-talk between adjacent photomultipler detec- tors. The PV 8050 is fitted with a single and the PV 8055 with a dual excitation stand. The PV 8060 is optimised for ICP, with a high-performance Boumans source unit, constant focus achromatic entrance optics and easy height adjustment. The PV 8065 is equipped for both spark source and ICP excitation, with automatic back- Philips Scientific and Industrial Equip- ment, 5600 Eindhoven, The Netherlands.Scanning Electron Microscopes The Philips SEM 515, with a 20 x 20 mm microstage, guarantees 5 nm resolution at 30 kV, with 4 nm easily attainable. The SEM 525 has a 310 mm high X 380 mm wide x 280mm deep specimen chamber and a 100 x 100mm stage that moves in both X and Y directions. The SEM 535 also has a large specimen chamber desig- ned to accept a wavelength-dispersive spectrometer. A new feature of these SEMs is microprocessor-controlled automatic focusing and astigmatism correction. Also, improved gun geometry gives high resolution and a better signal to noise ratio, and a special low kV configuration gives a 5-fold increase in brightness.Philips Scientific and Industrial Equip- ment, 5600 Eindhoven, The Netherlands. Digital Storage Oscilloscope The 4035 features automatic cursor measurements of time and voltage, dis- played in alphanumeric form on the screen, a built-in IEEE interface and an automatic plotter interface with the abil- ity to produce grids and scales along with plots of oscilloscope traces. An optional remote keypad allows a range of addi- tional operations to be carried out on stored traces, including mathematical manipulation, filtering, averaging and examination of individual TV lines. Gould Design and Test Systems Divi- sion, Roebuck Road, Hainault, Ilford, Essex, IG6 3UE. Laboratory Tubing Tygon R-3603 tubing will handle most chemicals found in the laboratory.Even where it is attacked by a specific chemical it can be used intermittently, for several hours of continuous contact, if it is thor- oughly flushed with water after each use. Soft and flexible, and with a flex life 10-12 times that of rubber, it is suitable for use with peristaltic pumps. Uniscience Ltd., 12-14 St. Ann’s Crescent, London, SW18 2LS. Tubing Clamps Made from a heat and corrosion resistant plastic, the clamps are available in two sizes for tubing up to 4.5 mm 0.d. or up to 14 mm 0.d. The design features a non-slip serrated wheel, which turns along a sloped floor, enabling infinitely variable flow control and one-handed operation. J. Bibby Science Products Ltd., Stone, Staffordshire, ST15 OSA. Laboratory Information Management System The LIMS/2000 is the latest in Perkin- Elmer’s camputer aided chemistry pro- gramme.It is designed to give total control over laboratory information flow,32 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 including sample status, workload, costs, productivity and laboratory performance. New advanced software allows laboratory throughput to be optimised by tracking samples through the laboratory, assigning test requirements to each sample, produc- ing worklists and backlog reports, collect- ing results automatically from instru- ments, taking data manually from termi- nals, generating a report for each sample and searching an archival data base according to any chosen criteria. The system can be introduced at various levels of complexity, and its flexibility allows it to be modified as necessary as the labora- tory’s needs develop. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghanishire , HP9 1QA.Literature A brochure describes the Model 3510 inductively coupled plasma spectrometer system. A refined version of its predeces- sor, the 35000 ICP, the new instrument is specifically suited for a broad range of liquids analysis of metals, glasses, Series 200 desktop computer. They allow the chemist to edit, search, analyse and report data directly from his desktop data system. Nelson Analytical Inc., 10061 Bubb Road, Cupertino, California 95014, USA. A brochure, Number 56, describes micro- bore HPLC columns. These offer an efficiency of 25-30 000 plates per column (50-60 m) for 10-pm particles. Columns of even higher efficiency are available with 5-ym particles.Alltech Associates Applied Science Ltd., 9a New Street, Carnforth, Lanca- shire, LA5 9BX. A catalogue contains details of a range of fused silica capillary columns, many for immediate delivery from stock and many as standard columns offered with over 40 different liquid phases in 25 or 50m lengths and 0.32 or 0.22mm i.d. Tailor- made columns can also be supplied. Chrompack UK Ltd., Unit 4, Indescon Court, Millharbour, London, E l 4 9TN. tions,” gives details of the first 85 installa- tions of Radiometer’s ION 85, which measures mV, pH, pX, temperature and ion concentration. V. A. Howe & Co. Ltd., 12-14 St. Ann’s Crescent, London, SW18 2LS. A booklet entitled “Thermal Analysis and Titration in Plastics,” one of a series of Application Digests, contains practical applications of the makers’ TA3000 ther- mal analysis system and the DL40RC MemoTitrator.The order number is 1.7573.72. Mettler Instrumente AG, CH-8606 Greifensee, Switzerland. A brochure decribes the Model TAW PCAl system, which provides a rapid and accurate method of particle size analysis of powders, emulsions and suspensions for research applications and routine quality control. Also available are biblio- graphies listing over 4000 references to the Coulter Principle (the subject of British Standard 3406: Part 5 ) . Coulter Electronics Ltd., Northwell Drive, Luton. Bedfordshire, LU3 3RH. A colour poster is available, price f5, giving instruction on what to do for someone suffering from electric shock. It is designed to enable companies to com- ply with the legislation, which requires that “instructions as to the treatment of persons suffering from electric shock shall be affixed in all premises where electrical energy is generated, transformed or used above low pressure.” Also available are free safety signs wall charts. Companies were given five years from the beginning of January 1981 to replace old signs with new standard safety signs and colours which are uniform throughout the European Community . British Safety Council, 62-64 Chan- cellor’s Road, London, W6 9RS. ARL Model 3510 ICP cements, and ceramics in solution. An optional hydride generator provides 20- 400 times better detection limits for Pb, Hg, Se, Bi, Sb, As, Sn, Ge and Te. Applied Research Laboratories, Bausch and Lomb UK Ltd., Wingate Road, Luton, Bedfordshire, LU4 8PU. A brochure outlines the capabilities of new data base management software for laboratory applications. The new pack- ages are available for operation on the Series 4400 chromatography data system, which is based on the Hewlett-Packard A leaflet describes a gel-permeation chro- matography package designed for size- exclusion chromatography with polymers such as acrylics and epoxies, plastics and proteins. Based on the HP1090 liquid chromatograph, it offers ultraviolet - visible and/or refractive index detection and advanced results calculation and report. Hewlett Packard Ltd., Miller House, The Ring, Bracknell, Berkshire, RG12 1XN. A booklet, “ION 85, the First 85 Installa-

ISSN:0144-557X    

DOI:10.1039/AP9852200028

出版商:RSC    

年代:1985

数据来源: RSC

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32 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 1984 TMG Award Dr. A. Atiq Rahman has won the Third Thermal Methods Group Award of the Royal Society of Chemistry for his essay on the “Application of Thermal Analysis in Surface Chemical Investigation of Zir- conia Gels.” The formal presentation of the award was made to Dr. Rahman at the Third European Symposium on Thermal Analysis and Calorimetry (ESTAC 3) held in September, 1984, at Interlaken, Switzerland. The previous (second) TMG award was presented in 1981. Dr. Rahman, a solid-state and surface chemist, was born and initially educatedANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 Dr. A . A. Rahman in Bangladesh, where he also taught chemistry at Dacca University. He com- pleted his PhD at Brunel University in 1977. After a short period of postdoctoral work at Brunel University he was invited to the Centre des Recherches sur la Physico-chemie des Surfaces Solides, Mulhouse, France, where he researched in and taught Chemical Engineering up to 1979.Later he joined the Department of Metallurgy and Science of Materials, Uni- versity of Oxford, and started his research on chemistry and material science of cementitious materials. He joined Uni- versity of Aberdeen in 1981 and is presently working there as a Research Fellow. His fields of specialization in chemistry are porous solids. building materials and catalysis, and energy, environmental and powder technologies. He is involved in issues of development, technology choice, science - technology policies and environment and energy issues, particul- arly of developing countries. He is a consultant to the Centre of Research of New International Economic Order, Oxford. and the International Organiza- tion of Chemical Sciences for Develop- ment (IOCD). In July, 1984, he gave the invited lecture in the Third World Confer- ence on Chemical Research Applied to World Needs held in The Hague, Hol- land. He was invited to speak on “New and Renewable Sources of Energy and Building Materials Technology for Devel- oping Countries.” Dr. Rahman has been a Member of Royal Society of Chemistry since 1977. 33

ISSN:0144-557X    

DOI:10.1039/AP9852200032

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 33 Publications Received Alcohols with Water. Edited by A. F. M. Barton. Solubility Data Series, Volume 15. Pp. xx + 438. Pergamon Press. 1984. Price &64: $100. ISBN 0 08 025276 1. Health and Safety for Toxicity Testing. Douglas B. Walters and C. W. Jameson. Pp. xvi + 339. Butterworths. 1984. Price f42.50. ISBN 0 250 40546 6. Methods of Protein Analysis. Edited by Istvan Kerese. Ellis Horwood Series in Analytical Chemistry. Pp. 371. Ellis Horwood and Akadkmiai Kiado. 1984. Price f39.50. ISBN 0 85312 176 1 (Ellis Horwood); 0 470 27497 2 (Halsted Press). Analytikum. Methoden der Analytischen Chemie und ihre Theoretischen Grund- lagen. 6 durchgesehene Auflage. Edited by K. Doerffel and R. Geyer. Pp. 616. VEB Deutscher Verlag fur Grund- stoffindustrie, Leipzig.1971. Price DM55. Lithium Battery Technology. Edited by H. V. Venkatasetty. Electro- chemical Society Monograph Series. Pp. xvi + 247. 1984. Price f43.50. ISBN 0 471 09609 1. VLSI Electronics Microstructure Science. Volume 7. Edited by Norman G. Einspruch. Pp. xii + 401. Academic Press. 1983. Price $59.50. ISBN 0 12 234107 4. Laboratory Techniques in Electroanaly- tical Chemistry. Edited by Peter T. Kissinger and William R. Heineman. Pp. xviii + 751. Marcel Dekker. 1984. Price $34.75 (U.S. and Canada); $41.50; SwFr98 (all other coun- tries). ISBN 0 8247 1864 X. This comprehensive book contains 24 chapters: An Overview: Fundamental Concepts of Analytical Electrochemistry; Large-Amplitude Controlled-Potential Techniques; Small-Amplitude and Re- lated Controlled-Potential Techniques; Introduction to Analog Instrumentation; Overcoming Solution Resistance with Stability and Grace in Potentiostatic Cir- cuits; Conductivity and Conductometry; Mercury Electrodes; Carbon Electrodes; Film Electrodes; Electrochemical Cells; Solvents and Supporting Electrolytes; Vacuum Line Techniques; Electroche- mistry in the Dry Box; Digital Simulation of Electrochemical Problems; Electro- chemical Evaluation of the Mechanisms of Organic Reactions Through Examples; Selected Aspects of Transition Metal34 ANALYTICAL PROCEEDINGS.JANUARY 1985, VOL 22 Electrochemistry; Electrochemical Pre- concentration; Constant-Current Coulo- metry; Application of Electrochemistry to Pharmaceutical Analysis; Electro- chemical Detection in Liquid Chromato- graphy and Flow Injection Analysis; Pho- toelectrochemistry and Electrochemilu- minescence; Principles and Techniques of Electrochemical-Electron Spin Reson- ance Experiments.Microprocessor Programming and Appli- cations for Scientists and Engineers. Richard S. Smardzewski. Data Handling in Science and Technology, Volume 1. Pp. xiv + 353. Elsevier. 1984. Price $37.75; Dfl98. ISBN 0 444 42407 (Vol. 1); 0 444 42408 3 (Series). Chemistry Experiments for Instrumental Met hods. Donald T. Sawyer, William R. Heineman and Janice M. Beebe. Pp. xviii + 427. Wiley. 1984. Price 518.35. ISBN 0 471 89303 X. Line Coincidence Tables for Inductively Coupled Plasma Atomic Emission Spec- trometry. Second Edition. Volumes 1 and 2. P. W. J. M. Boumans.Pp. xxvi + 34 + Tables 1-410 (Volume 1); viii + Tables 411-896 (Volume 2). Pergamon Press. 1984. Price f135; $215. ISBN 0 08 031404 X. Die Chemische Industrie und ihre Helfer, 1984/1985. Informationswerk uber die deutsche chemische Industrie und ihre Zulieferer. Edition Selka. Pp. iv + 498. Industrieschau- Verlagsgeselleschaft MbH. 1984. Price DM46. ISBN 3 7790 0154 3. Quality Assurance Principles For Ana- lytical Laboratories. Frederick M. Garfield. Pp. vi + 212. AOAC. 1984. Price $41.25 (members in USA); $45.50 (non-members in USA); $44.25 (members outside USA); $48.50 (non-members outside USA). Modern Methods of Particle Size Analysis. Edited by Howard G. Barth. Chemical Analysis, Volume 73. Pp. x + 309. Wiley- Interscience. 1984. Price f58.50. ISBN 0 471 87571 6.The nine chapters are as follows: “Com- mercial Instrumentation for Particle Size Analysis”; “The Application of Particle Characterization Methods to Submicron Dispersions and Emulsions”; “Particle Sizing Using Photon Correlation Spectro- scopy”; “Application of Photon Correla- tion Function Profile Analysis to Mole- cular Weight Distributions of Polymers in Solution”; “Particle and Droplet Sizing Using Fraunhofer Diffraction”; “Particle Size Measurements from 0.1 to 1000 ym Based on Light Scattering and Diffrac- tion”; “Filed-flow Fractionation of Par- ticles”; “Detection Systems for Particle Chromatography” ; “Hydrodynamic Chromatography of High Molecular Weight Water-soluble Polymers.” Contemporary Practice of Chromato- Colin F. Poole and Sheila A. Schuette.Pp. x + 708. Elsevier. 1984. Price $61.25; Dfl159. ISBN 0 444 42410 5. Chapter titles are as follows: Fundamen- tal Relationship of Chromatography; The Column in Gas Chromatography; Instrumental Requirements for Gas Chromatography; The Column in Liquid Chromatography; Instrumental Require- ments for High Performance Liquid Chromatography; Preparative-scale Chromatography; Sample Preparation for Chromatographic Analysis; Hyphenated Methods for Identification After Chro- matographic Separation; and High Per- formance Thin-layer Chromatography. graphy Trace Analysis, Volume 3. Edited by James F. Lawrence. Pp. xii + 258. Academic Press. Price $49.50; 535. ISBN 0 12 682103 8. Chapter titles are as follows: Recent Developments in the Determination of Carbonyl Compounds in Biological Fluids and Tissues; Recent Developments in Enzymatic Methods for Clinical Analysis; Chlorinated Hydrocarbon Residues in Primate Tissues and Fluids; Analysis of Ascorbic Acid and Related Compounds in Fluids and Tissues; Recent Develop- ments in Therapeutic Drug Monitoring of Antiepileptic Drugs; Determination of Environmental Pollutants by Direct Fluorescence Spectroscopy and Analysis of Polycyclic Aromatic Compounds in Combustion Emissions.

ISSN:0144-557X    

DOI:10.1039/AP985220033b

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

34 ANALYTICAL PROCEEDINGS. JANUARY 1985, VOL 22 Conferences and Meetings Pittsburgh Conference and Exposition on Analytical Chemistry and Applied Spec- troscopy February 25-March 1, 1985, New Orleans, LA, USA The 1985 Pittsburgh Conference will be held in the New Orleans Convention Center. Among the features of the confer- ence will be a workshop on “Personal Computers in the Laboratory.” The symposia will include “Toxic Waste Analysis - Water Pollution Analysis,” “Advances in Mass Spectrometry,’’ “Computers in Analytical Instrumenta- tion,” “Biomedical Infrared Spectro- scopy,” “Microbore Liquid Chromato- graphy,” “Chemometrics and Process Analytical Chemistry,” “New Dimen- sions in Particle Size and Shape Technol- ogies,” “Flow Injection Analysis,” “Small Area Solid and Surface Analysis,” “Application of Optical Fibres and Lasers to Chemical Analysis ,” “New Advances in Raman Spectroscopy,” “Near Infrared Analysis,” “Reaction Detectors in Liquid Chromatography,” “Analytical Applica- tions of Micellar Solution’’ and “Planar Chromatography.” For further information write to the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, 437 Donald Road, Pittsburgh, PA 15235, USA. American Oil Chemists Society Calendar of Meetings, 1985 AOCS meetings in 1985 of possible interest to analytical chemists will be as follows. April 30-May 1, short course on Processing Quality Control of Fats and Oils, Hershey Poconos, White Haven, PA; May 2 4 , short course on Applica- tions of Analytical Methodology in Fats and Oil Processing, Hershey Poconos, White Haven, PA; May 5-9,76th Annual Meeting of the American Oil Chemists Society, Wyndham Franklin Plaza Hotel, Philadelphia PA.For information about these meetings write to the Meetings Co-ordinator, American Oil Chemists Society, 508 S. Sixth Street. Chamnaign. IL 61820. USA. Hewlett-Packard Analytical Symposium June 10-14, 1985, Stra ford- Upon-Avon The 1985 symposium will again be held at the Moat House International Hotel. The programme will be extended to cover laboratory automation, spectroscopy and biotechnology in addition to advances in HPLC, gas chromatography and mass spectrometry. For advance registration information please contact Mrs. Tina Mears, Hewlett-Packard Limited, Miller House, The Ring, Bracknell, Berkshire. International Symposium on Drug Analy- sis: Current Challenges September 9-10, 1985, Ottawa, Canada This meeting, which is sponsored by Health and Welfare Canada, is a satellite symposium of the 45th International Con- gress of the Pharmaceutical Sciences of the Fkderation Internationale Pharma- ceutique.Posters are being sought for the meeting, the main topics of discussion being dosage forms (emerging standards, colours, intravenous nutrients, impuri- I - 1 0 ’ ties, hormonal pharmaceuticals), biolog-ANALYTICAL PROCEEDINGS, JANUARY 1085, VOL 22 35 ical fluids (pharmacokinetic studies, mor- phinoids, CNS drugs, cyclosporine, digoxin, calcium channel (blockers) and analytical techniques (micro-bore HPLC, mass spectrometry, NMR spectrometry, immunoassays, computer assisted ana- lysis, quality assurance).For further information contact Dr. G . L. Mattock, Bureau of Drug Research, Health Protection Branch, Tunney’s Pas- ture, Ottawa, Ontario, Canada K1A OL2. Colloquium Spectroscopicum Internation- ale XXIV September 15-21, 1985, Garrnisch- Partenkirchen, FRG This meeting, which will be held under the auspices of the Gesellschaft Deutscher Chemiker and the Deutsche BunsenGesellschaft fin- Physikalische Chemie, will be held at the Kongresshaus in Garmisch-Partenkirchen. The topics for discussion (for which posters are sought) fall into two groups. The first group, Basic Theory and Methods, includes Atomic-emission Spectroscopy, Atomic-absorption Spectrometry, Atomic-fluorescence Spectrometry, X-ray Emission and Fluorescence Spec- trometry, Methods of Surface Analysis and Depth Profiling, Infrared and Raman Spectroscopy, Molecular Spectroscopy (UV and Visible), Nuclear Magnetic Resonance Spectroscopy (NMR) , Radia- tion Detectors, Data Recording and Han- dling, Laser Spectroscopy, Mass Spectro- scopy (organic and inorganic), Activation Analysis and Standard Reference Materials.The second group, Analytical Applications for Specific Problems, are Analysis of Metals, Analysis of Various Industrial Products, Geochemical Ana- lysis, Biological, Chemical and Phar- maceutical Analysis, Analysis in Agricul- ture and Nutrition Chemistry, Environ- mental Analysis and Sample Preparation. In addition to the papers and posters, there will be a public lecture after the opening ceremony by W. Priester on “From Big Bang to Black Holes,” and an instrument ex hi bi tion.For further details write to Gesellschaft Deutscher Chemiker, Abteilung Tagung- sorganisation, Postfach 90 04 40, D-6000 Frankfurt am Main 90, Bundesrepublik Deutschland. Sixth International Congress of Pesticide Chemistry August 10-17, 1986, Ottawa, Canada Details of this meeting are available from T. H. G. Micheal, Chemical Institute of Canada, 151 Slater Street, Suite 906, Ottawa, Ontario, Canada K1P 5H3. Tenth International Symposium on Micro- chemical Techniques August 25-29, 1986, Antwerp, Belgium ISM-10 will cover both pure and applied aspects of analytical chemistry related to micro- and trace analysis. A special work- shop on laser microprobe mass analysis (LAMMA) is planned, while special attention will be paid to the application of modern techniques in the field of trace analysis. Both oral and poster-session papers can be submitted, although plen- ary and keynote lectures will be presented by invited speakers. For further information contact Dr. R. Dewolfs, University of Antwerp (UIA), Department of Chemistry, Universiteit- splein 1, B-2610 Wilrijk, Belgium.

ISSN:0144-557X    

DOI:10.1039/AP9852200034

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, JANUARY 1085, VOL 22 35 Courses Safety of Electrical Equipment in Poten- tially Explosive Atmospheres March 2&22, 1985, Burton Sira’s three-day residential course on the above topic, which will be held at Burton Manor, Burton, Cheshire, introduces delegates to the relevant standards and codes of practice and gives guidance on methods of interpretation and practical implementation. Lecturers and tutors are drawn from Sira Safety Services Ltd., Measurement Technology Ltd. and Expo Safety Systems Ltd. Course participants will acquire a sound understanding of the basic require- ments that must be met to ensure the safe operation of instrumentation and other electrical equipment installed where explosive atmospheres may occur (excluding those existing underground in coal mines).The programme progresses from the problems of area classification, through the selection of equipment, to installation and maintenance. As well as lectures and tutorials, there are practical sessions which emphasise the application of intrinsic safety as this is the most common form of protection used for instrumentation and light current elec- trical equipment. The course is suitable for: engineers and scientists engaged in design, development and research; chief engineers and technical managers con- cerned with industrial process control; and engineers involved in installation, maintenance and inspection work. Further information can be obtained from the Conference Unit, Sira Ltd., South Hill, Chislehurst, Kent BR7 5EH. In addition, companies can commission courses on the use of electrical apparatus or instrumentation in potentially explo- sive atmospheres for their employees.For information on these contact G. Tortoi- shell, Sira Safety Devices Ltd., Saighton Lane, Saighton, Chester CH3 6EG. Loughborough Short Courses Spring and Summer, 1985 The following short courses will be held in the Department of Chemistry at the University of Technology during 1985. Separations for Biotechnology and Bio- chemistry, March 25-29, 1985, fee $300 including residence and all meals; Gas - Liquid Chromatography, April 15-19, 1985, fee f300 including residence and all meals; Radioisotope Techniques, June 24-28, 1985, fee f275 including residence and all meals; Statistics for Analytical Chemistry, July 8-11, 1985, fee $230 including residence and all meals; High- performance Liquid Chromatography, September 23-27, 1985, fee f300 includ- ing residence and all meals.Further details are available from: Miss C. D. Newton, Department of Chemistry, Loughborough University of Technology, Loughborough , Leicestershire LE11 3TU. Amsterdam Summer School on HPLC June 17-21, 1985, Amsterdam, The Netherlands This course will provide a coherent over- view of high-performance liquid chroma- tography as an analytical and preparative technique. Fundamental aspects of theory and instrumentation will be treated in lectures and seminars by leading inter- national experts in the field. The course includes practical experiments in order to illustrate the potential of the technique. The summer school will be organized by the Separation Group of Professor H. Poppe and Dr. J. C. Kraak. The official language will be English. Information and registration can be obtained through the Municipal Congress Bureau, Oudezijds Achterburgwal 199, 1012 DK Amsterdam, The Netherlands. Practical Ultraviolet and Fluorescence Spectrometry July 15-19, 1985, Loughborough A short course on this topic will be held at Loughborough University of Technology. The cost will be f300 including residence and all meals. For further information contact Miss C. D. Newton, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire LE11 3TU.

ISSN:0144-557X    

DOI:10.1039/AP9852200035

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

36 ANALYTICAL PROCEEDINGS, JANUARY 1985, VOL 22 Analytical Division Diary JANUARY Wednesday, 23rd, 6.30 p.m.: London Microchemical Methods and Atomic Spectroscopy Groups: Analysis by ICP - MS: Novelty or Reality? The first paper describing the use of the ICP as an ion source for atomic mass spectrometry appeared in 1980, but a viable form of the ICP - MS technique was only presented in 1982. Delivery of the first commercial systems began in March 1984, and by the end of the year at least 20 instruments had been shipped by two manufacturers. In view of the limited number of development and applications papers that have been publi- shed since 1982, is this apparent faith in a new method of analysis justified? Current performance will be discussed. Introduced by A. R. Date. The Savoy Tavern, Savoy Street, London, W.C.2.There are no registration formalities. Contact: Mr. P. R. W. Baker, 55 Braemar Gardens, West Discussion Meeting. Wickham, Kent BR4 OJN. (Tel. 01-777-1225). Friday, 25th: London Thermal Methods Group Thermal Methods for Assessing the Hazards and Safety of Chemical Reactions. Speakers to include: M. Ottaway, C. Coats and J. Leckenby. Scientific Societies Lecture Theatre, 23 Savile Row, Lon- Registration is necessary; approximate cost f45. Contact: Dr. C. J. Keattch, Industrial and Laboratory Services, P.O. Box 9, Lyme Regis, Dorset. (Tel. 02974- 2472). don, W.l. FEBRUARY Wednesday, 6th, 11 a.m.: London Analytical Division, in conjunction with the Electroanalytical Modified Electrodes. “Modified Electrodes, Fundamentals, Prospects and Needs for “Modified Electrodes for Trace Analysis of Metals with no Mercury “Ferrocene-based Enzyme Electrodes,” by H.A. 0. Hill. “The Modification and Preparation of Electrodes by Dynamic Recoil Mixing,” by Michael L. Hitchman. “Voltammetry of Molecules of Pharmacological Importance at Modified Electrodes: an Analytical and Mechanistic Point of View,” by G. J. Patriarche. Group. Chemical Analysis,” by Royce W. Murray. and no Deoxygenation,” by G. C. Wallace. Discussion session led by Royce W. Murray. Scientific Societies Lecture Theatre, 23 Savile Row, Lon- don, W.l. Registration is necessary. Cost f15 to RSC members, f25 to non-members and f 7 to students and retired members. Contact: Miss P. E. Hutchinson, Analytical Division, Royal Society of Chemistry, Burlington House, London W1V OBN.(Tel. 01-734-9971). Wednesday, 13th, 7 p.m.: Moreton North West Region. Aspects of Analytical Chemistry in Hospital Laboratories. Speaker: T. B. Hales. E. R. Squibb & Sons Laboratories, Reeds Lane, Moreton, Registration is necessary; no charge. Contact: Mr. T. E. Hanley, 5 Old Hall Court, Ashton, Near Wirral. Chester, Cheshire. (Tel. 0829-51609). Thursday, 14th, 10 a.m.: Leatherhead South East Region. Application of Near Infrared Spectroscopy in the Food Industry. Introduction by J . C. Fry. “Problems in Conventional Oilseed Analysis Using NIR and NMR, “Application of NIR in the Quality Control of Biscuit Flour,” by “The Statistics of NIR Calibration,” by B. G. Osborne. “Recent Uses of NIR in Foodstuffs Analyses,” by A.Davies. “NIR Applications in the Dairy Industry,” by D. Bartley. “Application of NIR to Seed Stock Analysis,” by D. Smith. “Uses of NIR in the Analyses of Brewing Materials,” by Miss Halsey. Pacific Scientific (Neotec) and Technicon will be on site to demonstrate equipment and answer questions. British Food Manufacturing Industries Research Associa- tion, Leatherhead. Registration is necessary. Cost f12.50 to RSC members, f17.50 to non-members. Contact: Mr. P. J. O’Neil, Laboratory of the Government Chemist, Cornwall House, Stamford Street, London SE1 9NQ. (Tel. 01-928-7900, Ex. 614). Especially with Reference to Soya,” by B. J. Rossell. K. M. Cowley. Friday, 15th, 5.15 p.m.: Plymouth Western Region, jointly with the Peninsula Section of the Spectroscopic Analysis of Natural Waters, Limitations and Developments.Speaker: D. L. Miles. Chemistry Department, The Polytechnic, Plymouth. There are no registration formalities. Contact: Mr. F. W. Sweeting, Wessex Water Authority, Bristol Avon Division, P.O. Box 95, The Ambury, Bath BA1 2YP. (Tel. 0225-313500, Ex. 278). RSC. Tuesday, 19th, 4.15 p.m.: Loughborough Midlands Region, jointly with the Loughborough University To Blow or to Bleed-The Drinking Driver’s Dilemma. The talk will cover the developments in blood, urine and breath analysis for drinking drivers and the associated problems of evidential breath test machines. Speaker: R. Denney. Lecture Theatre 5002, Edward Herbert Building, University of Technology, Loughborough. There are no registration formalities. Contact: Mr.H. E. Brookes, 35 Dunster Road, West Bridgford, Nottingham NG2 6JE. (Tel. 0602-231769). Student Chemical Society. [continued inside back coverAnalytical Division Diary, continued February, continued Tuesday, 19th, 4.10 p.m.: Swansea Western Region, jointly with the South West Wales Section of the RSC. Microscopy Techniques in Industry. Speaker: J . R . Muriss. Chemistry Department, University College, Swansea. There are no registration formalities. Contact: Mr. F. W. Sweeting, Wessex Water Authority. Bristol Avon Division, P.O. Box 95, The Ambury, Bath BAI 2YP. (Tel. 0225-313500, Ex. 278). Wednesday, 20th, 6.30 p.m.: London Microchemical Methods and Chromatography and Electro- Recent Advances in UV Instrumentation. The speaker will review recent advances in instrumentation for visible and UV spectrometry, including applications to HPLC.The impact of the microprocessor in instrument control, data handling and storage and of diode array detection systems will be considered. Speaker: M. A. Russell. The Savoy Tavern, Savoy Street, London, W.C.2. There are no registration formalities. Contact: Mr. P. R. W. Baker, 55 Braemar Gardens, West phoresis Groups: Discussion Meeting. Wickham, Kent BR4 OJN. (Tel. 01-777-1225). Wednesday, 20th, 10 a.m.: London Special Techniques Group, jointly with the Institute of Fibre Optics for Chemical Sensing. “Optical Fibres in Chemical “Fibre Optic Interferometric Thermometers and Their Possible Application to Chemical Reaction Sensing,” by D. A. Jackson or J . D. C. Jones. “Photometric Measurement in Chemical Analysis Using Fibre Optics,” by J .H. G. Knight or A. G. Green. “The Application of Single Optical Fibres to Remote Absorption Measurements,” by L. A. Milliard. “Instrumentation for Analysing Optical Sensor Output,” by D. N . McFadyen. “Biomedical Sensing Using Optical Fibres,” by A. M. Smith. “Development of a Fibre Optic Based System for Monitoring Water Vapour in Remote Hazardous Environments,” by M. Robson. “Spectral Filtering Optical Fibre Sensors,” by J . Dakin. Read Lecture Theatre , Sherfield Building, Imperial College, Registration is necessary. Cost E35 to RSC members, f40 to Physics. nalysis,” by R. Narayanaswamy. South Kensington, London S.W.7. non-members and &5 (excluding lunch) to students. Contact: Mr. A. G .Ferrige, Wellcome Research Labora- tories, Langley Court, Beckenham, Kent BR3 3BS. (Tel. 01-658-2211, EX. 357). Wednesday, 20th, 1.20 p.m.: Hull North East Region. Estuarine Analysis. “Chemical Variability and Reactivity in Estuaries: Challenges to the Analytical Chemist,” by A. W. Morris. “Humber Estuary Committee-Analytical Quality Control,” by B . T. Croll. “Practical Problems of Trace Metal Determination in the Mersey Estuary,” by A. Gunn. “Metalloid Speciation Analysis in Rough and Smooth Waters,” by A. G. Howard. Lecture Theatre A, Chemistry Department, The University, Hull. Registration is necessary. Cost f10 to RSC members, f15 to non-members and f 5 to student and retired members. Contact: Dr. P. Worsfold, Chemistry Department, The University, Hull HU6 7RX.(Tel. 0482-46311). Thursday, 21st, 4.15 p.m.: Aberdeen Scottish Region, jointly with the Aberdeen and North of Scotland Section of the RSC and the Aberdeen University Students Chemical Society. Analytical Chemistry in Wee Pipes-Concepts and Applica- tion of Flow Injection Analysis. Speaker: J . F. Tyson. Department of Chemistry, The University, Aberdeen. There are no registration formalities. Contact: Dr. Janet M. Warren, Department of Bio- chemistry, Royal Infirmary, Glasgow G4 OSF. (Tel. 041-552-3535, EX. 5108). Tuesday, 26th, 4.30 p.m.: Edinburgh Scotland Section of the RSC. Scottish Region, jointly with the Edinburgh and South East Forensic Analysis: Much Ado About Next to Nothing. A discussion of the factors needed for successful forensic analysis in relation to recent developments in methods and the problems which now beset the analyst in the present economic and legal climate. Speaker: R. L. Williams. Department of Chemistry, University of Edinburgh, Kings There are no registration formalities. Contact: Dr. Janet M. Warren, Department of Bio- chemistry, Royal Infirmary, Glasgow G4 OSF. (Tel. Buildings, West Mains Road, Edinburgh. 041-552-3535, EX. 5108).

ISSN:0144-557X    

DOI:10.1039/AP9852200036

出版商:RSC    

年代:1985

数据来源: RSC