摘要:

Proceedinas - of the Analytical Division ofThe Chemical SocietyCONTENTS307 Reports of Meetings308 Summaries of Papers308 'The Application of NewTechniques in EnvironmentalA na I ysi s'321 Application of Computers,Particularly Microprocessors, toAutomatic AnalyticalInstrumentation'323 Conferences and Meetings324 Analytical Chemistry Trust Fund324 Chemical Society Library325 Publications Received328 Analytical Division DiaryVolume 12 No 12 Pages 307-328 December 197PADSDZ 12(12)307-328(1975)ISSN 0306-1 396December 1975PROCEEDINGSOF THEANALYTICAL DIVISION OF THE CHEMICAL SOCIETYOfficers of the Analytical Divisionof the Chemical SocietyPresidentG. W. C. MilnerHon. SecretaryP. G . W. CobbSecretaryMiss P. E. HutchinsonHon. Treasurer Hon.Assistant SecretariesJ. K. Foreman D. I. Coomber, O.B.E.; D. W. WilsonEditor, ProceedingsP. C. WestonProceedings is published by The Chemical Society.Editorial: The Director of Publications, The Chemical Society, Burlington House, London, W1 V OBN.Telephone 01 -734 9864. Telex 268001.Subscriptions (non-members): The Chemical Society, Publications Sales Office, Blackhorse Road, Letch-worth, Herts., SG6 1HN.Nonmembers can only be supplied with Proceedings as part of a combined subscription with The Analystand Analytical Abstracts.@ The Chemical Society 1975Analytical Abstracts-Quinquennial IndexVolumes I1 -1 5 : 1964-1 968This cumulative index is in t w o separate parts: the Author section (912 pages) and theSubject section (579 pages), It covers 35800 abstracts of the international literatureon all branches of analytical chemistry. The comprehensive alphabetical subject indexcontains almost I00000 entries and the author index includes titles, as well as the namesof all authors.Clothbound, 9s” x 6&”, set of t w o Volumes f70.00CS Members’ price f60.00Decennial Index - Volumes 1-10: 1954-1963The earlier cumulative index, also in two separate parts: author section (1033 pages)and subject section (680 pages), covers 46200 abstracts. It is being offered for alimited period at a special reduced price if ordered with the Quinquennial Index.Decennial and Quinquennial Indexes, set of four Volumes f80.00CS Members’ price f 65.00Orders should be sent direct, with remittance, or through your usual bookseller to-Tlie Publications Sales Officer, The Chemical Society, Blackhorse Road, Letchworth,Herts, SG6 I H N

ISSN:0306-1396    

DOI:10.1039/AD97512FX043

出版商:RSC    

年代:1975

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Analytical Division DiaryDECEMBERFriday, 19th, 10 a.m.: East KilbrideScottish Region, jointly with the MineralogicalSociety and the Edinburgh and GlasgowGeological Societies on “Determination andInterpretation of Rare Earth Abundancesin Rocks and Minerals.”Scottish Universities Research and ReactorCentre, East Kilbride.JANUARYThursday, 8th, 11 a.m.: SheffieldAnalytical Division, organised by the AtomicSpectroscopy Group and the EditorialBoard of ARAAS, jointly with the ModernMethods of Analysis Group of the SheffieldMetallurgical and Engineering Association :Third Reports on Analytical AtomicSpectroscopy Symposium.“Experiences with the Inductively CoupledPlasma,” by S. R. Koirtyohann.“Simultaneous Analysis with Atomic Ab-sorption, Emission and Atomic Fluores-cence Spectrometry,” by N.Omenetto.“Excitation Sources for Atomic Spectro-scopy,” by B. L. Sharp.Lane, Sheffield, S10 3AY.Ranmoor House, The University, ShoreTuesday, 20th, 6.30 p.m. : CoventryMidlands Region : Elwell Award Mceting.“The Determination of Phosphorus Com-pounds by MECA,” by 0. Osibanjo.“Analytical Aspects of Gas-phase AugerElectron Spectrometry,” by P. A. Hewitt.The programme will be completed by severalother short contributions.Lecture Theatre T, 19, Lanchester Polytechnic,Coventry.Wednesday, 21st, 7.15 p.m.: Darlingtonfollowed by an Ordinary Meeting.“Biochemical Methods of Analysis,” by P.Novth E a s t Region : Annual General Meeting,Trinder .Europa Lodge Hotel, Blackwell Grange,Darlington.Friday, 23rd, 6.30 p.m. : Salford.Novth W e s t Region : Annual General Meeting,followed by an Ordinary Meeting.“Catalytic Methods in Chemistry,” by G.Svehla.The University, Salford.Friday, 23rd, 6 p.m.: BathWestevn Region : Annual General Meeting,followed by the Address of the retiringChairman, Dr W. J. Williams.Bath.Department of Chemistry, The University,Tuesday, 27th, 6.15 p.m.: LondonSouth E a s t Region : Annual General Meeting,followed by an Ordinary Meeting.“Research and Testing for the Consumer,”by P. Sand.lington House, Piccadilly, London, W. l .The Linnean Society Meeting Room, Bur-Printed by Heffers Printers Ltd Cambridge Englan

ISSN:0306-1396    

DOI:10.1039/AD97512BX045

出版商:RSC    

年代:1975

数据来源: RSC

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Vol. 12 No. 12 December 1975 of the Analytical Division of the Chemical Society Reports of Meetings Ordinary Meeting An Ordinary Meeting of the Division was held a t 11 a.m. on Wednesday, December 3rd, 1975, in the Scientific Societies Lecture Theatre, 23 Savile Row, London, W.l. The Chair was taken by the President, Dr. G. W. C. Milner. The subject of the meeting was “Laser Applications in Analysis” and the folIowing papers were presented and discussed : “Laser Design,” by J .C. McGurk; “The Value of Lasers t o the Chemist-A Survey,” by P. J. Hendra; “Pulsed Laser Techniques and their Applications,’’ by E. Reid ; “Laser Techniques for Pollution Monitoring,” by E. L. Thomas; “Laser Raman Spectroscopy,” by H. E. Hallam; “Raman Spectroscopy of Species in Flames and Other High Temperature Measurements,” by P.J. Hendra; “The Analysis of Solid Materials by Laser Probe Mass Spectrometry,” by I<. A. Ringham. North West Region A Joint Meeting of the Region with the Lancaster and District Section of the CS was held at 7.30 p.m. on Thursday, November 13th, 1975, in the Polytechnic, Preston. The Chair was taken by the Chairman of the Region, Dr.L. S. Bark. A lecture on “Ion-selective Electrodes” was given by Mr. J. Entwistle. Scottish Region A Joint Meeting of the Region with the Glasgow and West of Scotland Section of the CS and the Andersonian Chemical Society was held at 4 p.m. on Thursday, November 20th, 1975, in the Chemistry Department, University of Strathclyde, Glasgow. The Chair was taken by the Chairman of the Glasgow and West of Scotland Section of the CS, Professor D.W. A. Sharp. A lecture on “Analytical Atomic Spectroscopy and the Environment” was given by J. M. Otta- way. Western Region An Ordinary Meeting of the Region was held at 7 p.m. on Friday, November 21st, 1975, in the George Hotel, Chepstow. The Chair was taken by the Chairman of the Kegion, Dr. G. Dickes. A discussion on “Auto-analysers in Environ- mental Analysis” was introduced by G.Jones. North East Region A Joint Meeting of the Region with the North East and North West Regions of the Association of Clinical Biochemists was held at 2 p.m. on Wednesday, November 12th, 1975, in the General Infirmary, Great George Street, Leeds. The Chair was taken by the Chairman of the latter body, Dr. W. H.Taylor. The subject of the meeting was “The Work and Training of a Clinical Biochemist” and the following papers were presented and discussed : “The Work of the Hospital Biochemist,” by F. E. Harper; “The Training of the Hospital Biochemist,” by C. Toothill; “Modern Concepts in Automated Analysis,” by P. M. G. Broughton. The papers were followed by a tour of the Teaching Hospital Laboratories.Joint Pharmaceutical Analysis Group An Ordinary Meeting of the Group was held a t 2 p.m. on Thursday, November 13th, 1975, at the Pharmaceutical Society of Great Britain, 17 Bloomsbury Square, London, W.C.1. The Chair was taken by the Chairman of the Group, Mr. G. I;. Phillips. The subject of the meeting was “Standards for Veterinary Medicines” and the following papers were presented and discussed : “The Need for Adequate Standards,’’ by Professor R. J . Fitzpatrick ; “The Relationship Between the Official View and the British Veterinary Codex,” by S. F. M. Davies; “Standards for Veterinary Medicines,” by D. J. Ringshaw ; “Does Industry Need a Veterinary Pharma- copoeia?” by E. Addison. 307

ISSN:0306-1396    

DOI:10.1039/AD9751200307

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

308 NEW TECHNIQUES IN ENVIRONMENTAL ANALYSIS Proc. Analyt. Div. Chem. SOC. The Application of New Techniques in Environmental Analysis The following are summaries of five of the papers presented at a Joint Meeting of the Scottish and North East Regions with the Microchemical Methods, Atomic Spectroscopy, Chromato- graphy and Electrophoresis, Automatic Methods and Electroanalytical Groups held on June 19th and 20th, 1975, and reported in the July issue of Proceedings (p.198). The Continuous Monitoring of Effluents Using Ion-selective Electrodes M. E. Hofton British Steel Corporation Research Centre (Teesside), Commerce W a y , P.O. Box 106, South B a n k , Middlesbrough, Cleveland, T S 6 6 U T The need for the constant monitoring of effluents arising from industry has long been recog- nised.Industry acknowledges the need to safeguard against unnecessary pollution of water courses, etc., and the now costly process of clearing the mess once pollution has occurred. On the other hand, the Water Authorities’ responsibilities towards ensuring a clean supply of water for public use means that they, too, must monitor rivers, etc., for that pollution.At the present time most monitoring of effluents is carried out by means of manual, random sampling of the effluent or river, but there is a growing need for continuous monitoring, particularly for inorganic ions and compounds which are the end products of either biological or chemical plants treating works effluents. For instance, a “high” in the concentration of a particular contaminant entering a river may have passed just before manual sampling took place and may have been missed.A more comprehensive picture of plant performance can be obtained by continuous analysis and a steady build-up in concentration of a particular ion may herald a possible forthcoming plant malfunction which can be rectified before any damage occurs. Manual analysis will not always give this warning until it is too late.The Use of Ion-selective Electrodes in Monitoring In general, ion-selective electrodes fulfil the requirements of any on-line system of monitor- ing. These requirements include reliability, accuracy, wide response range, rapid response, self-checking, ease of servicing and independence from human involvement. Of course not every species is capable of being measured by these electrodes but for those that are the use of ion-selective electrodes is generally more satisfactory than alternative techniques.A general monitor based on ion-selective electrodes consists of a series of separate units: the pumping system; the filtration system; the thermostated cell where the ion is sensed; and the electronic equipment handling the e.m.f.generated by the cell. These units are linked together either electronically or hydraulically through narrow-bore plastic tubing. Pumping and Filtration Equipment The type of pump most generally used to supply and mix the reagents and sample prior to measurement is of the peristaltic type, either multi-channel or single channel. In many of the applications involving these electrodes the effluent will contain an appre- ciable amount of solid material, including micro-organisms, which may grow inside the tubing and pumps, eventually causing a blockage.For this reason it is often necessary to include a filtration stage with a separate positive-displacement pump drawing the effluent through a membrane filter before being sampled by the monitor.For maximum protection the filter should remove all solids greater than 0.2 pm in diameter when the monitor is to be used on effluents from biological treatment plants. For general monitoring filtering to pass solids of 2-pm diameter is satisfactory.December, 1975 NEW TECHNIQUES IN ENVIRONMENTAL ANALYSIS 309 The Measurement Cell Measurement of the concentration of the species to be determined is carried out in a thermostated cell. The cell is made from Perspex and houses a small tube into which the effluent is pumped and the electrodes are dipped.The tube is immersed in a water-bath held at 30 0-5 "C by a small aquarium heater and a hydraulic thermostat. The solution enters the cell via a glass coil submerged in the water-bath which equilibrates the temperature of the test solution with that of the surrounding water-bath.The e.m.f. generated by the cell is passed on to an operational amplifier where either the whole calibration range of the electrode pair or selected ranges of the calibration can be presented on a recorder. In addition it is useful to have an alarm circuit where either a bell is sounded or a corrective procedure is initiated when a pre-selected concentration is reached.Auto-standardisation Most ion-selective electrodes are prone to drift. This drift is usually small and uniform over the whole calibration range and hence re-calibration can be easily accomplished by the intermittent sampling of a standard solution. Moreover, any drift in response at each re- standardisation can be corrected by either electronic or electro-mechanical offset of the output from the amplifier to the recorder.It is usual for the re-standardisation procedure to be initiated automatically every 6, 12 or 24 h, depending upon the severity of the drift in electrode response. The Electrodes Ion-selective electrodes suffer from a number of disadvantages, e.g., ion activity is measured and not concentration, and the slope of the response graph is temperature dependent. These factors must be considered when a monitor utilising ion-selective electrodes is developed.A comprehensive treatise on the effect of these factors on electrode response can be found in the literature.1,2 Potential Applications The steel industry generates a number of effluents, many of which are eventually discharged into rivers and there is a need therefore for monitoring equipment for ions such as cyanide, ammonium and fluoride, species which can easily be determined by use of ion-selective electrodes.The Determination of Cyanide As cyanide is extremely toxic very rigorous restrictions are imposed on its discharge For this reason the British Steel Corporation needs to be able to monitor its concentration at least down to the 0.05 p.p.m.level. In addition, the method used should discriminate between ionic cyanide and the relatively non-toxic complexes of cyanide [e.g., thiocyanate and hexacyanoferrate(III)]. The cyanide electrode marketed as such will just respond to cyanide at the 0.05 p.p.m. level but a 10-15-min delay is necessary before a steady-state response is recorded.More- over, investigation revealed that both thiocyanate and ammonia at the 0-5 and 100 p.p.m. levels, respectively, interfered with the response of the cyanide electrode. To relieve these problems an indirect procedure developed by Frant et aZ.3 was investigated with the idea of incorporating it in a continuous monitor for cyanide. In this procedure, potassium dicyanoargentate(1) is added to the test solution where any ionic cyanide present disturbs the equilibrium Ag(CN),-+Ag+ + 2CN- in favour of the removal of silver(1) ions from the solution.Consequently a silver ion-selective electrode can be used to monitor the changing concentration of silver(1) ions and hence the free cyanide concentration in the effluent test solution.Fig. 1 shows the flow diagram of the developed monitor, calibration being linear from 0 to at least 1 p.p.m. of cyanide. In practical terms the lowest limit of detection was 0.01 p.p.m. of cyanide. The time for each change in concentration of cyanide to be recorded was about310 NEW TECHNIQUES IN ENVIRONMENTAL ANALYSIS Proc. Analyt. Div. Chem. SOC. 10 min. This time was virtually independent of both the concentration of cyanide and whether ascending or descending concentrations were sampled. However, the time, measured from when the sample reached the pump until a steady state e.m.f.was recorded, was de- pendent upon the length of inter-connecting tubing between the units in the monitor. Perista It ic pumps (flow-rates in mt rnin-')v---, 1'1 Filter system Effluent return i L L----l Standard cyanide so I u t i o n - = 2MNaOH Solenoid valve I!I Constant-head device I ndicator + To waste Fig.1. Flow diagram of the cyanide monitor. Drifting in the electrode response was very slight, about 1 mV d-l towards a more positive potential. Moreover, as drifting was uniform over the whole of the calibration range the e.m.f.of any one standard solution of cyanide was used to re-formulate the entire calibration at re-standardisation. Of the potential interferents that may be found in British Steel Corporation effluents only sulphide causes any problems. This is because the silver ion-selective electrode incorporates a silver sulphide .membrane and is therefore equally responsive to sulphide and to silver ions.This problem therefore restricts its use to chemically or biologically pre-treated effluents unless the sulphide is removed before analysis by the addition of lead. The cyanide monitor has been successfully used to continuously monitor various types of effluents generated in steelworks. A more comprehensive treatise on the monitor and the on-line application can be found in the 1iteratu1-e.~ The Determination of Ammonia Because works' effluents are rich in ammonia gas and ammonium salts there is a need to monitor the efficiency of ammonia distillation plants in order to prevent overload of subsequent treatment plant and eventual pollution of rivers.For ammonia a gas-sensing electrode is used to monitor changes in concentration in the effluent.Sodium hydroxide solution is added to the effluent thus releasing ammonia gas through the gas permeable membrane of the ammonia electrode into an internal ammonium chloride solution. The resultant change in the pH of this solution is monitored by a conventional pH electrode. Because the number of interferents is restricted to those which generate acidic or basic gases (e.g., carbon dioxide and hydrogen sulphide) the technique is virtually interference free.The calibration of the monitor was linear from 1-2000 p.p.m. of ammonia with a slope of 53.8 mV per decade at 30 "C. The response time was about 8 min at the 1000 p.p.m. of ammonia level although it doubled at the lower limit of linearity.December, 1975 NEW TECHNIQUES I N ENVIRONMENTAL ANALYSIS 311 Problems with drift were more pronounced with the ammonia monitor than they were for cyanide (about 12 mV d-l towards a more positive potential).However, the use of the electronic “back-off” on the amplifier returned the e.m.f. generated on sampling the standard solution to its initial value, as is shown by the recorder trace for a 2-week monitoring period (Fig. 2). The analysis by an ion-selective electrode was compared with that by distillation and t i t r a t i ~ n .~ Agreement between results for the two procedures was within 5 per cent. At the levels of ammonia involved this agreement was considered excellent, particularly as the relationship between the e.m.f. of the cell and the ammonia concentration is logarithmic. c I - I NH3 content of effluent * E W 0 2 -140 .E 1000 - 2 =I % 0, ii= 750 - ~ 0 m Lc c, W CI c, c 500 - $ -130 8 200 - 0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 I“ O L z Timeld Fig. 2. of a steelworks. ammonia.* obtained by “monitor distillation.” Condensed recorder trace of the monitoring of ammonia in the effluent Standardisation peaks (corrected for drift) are from 200 pg ml-L of Ammonia contents shown a t each manual sampling point are those Conclusion The future of ion-selective electrodes in general is promising, with many possible applications in the steel industry for monitors utilising these electrodes, particularly in pollution monitor- ing.Their possible application is guided by the selectivity, the reliability and the accuracy of individual sensors and I look towards manufacturers to supply electrodes which have these characteristics.In choosing a system for continuous analysis the chemist must always look at alternative techniques, particularly colorimetry, as often they are more suited to a particular deter- mination. However, there will be many applications for, and manufacturers of, continuous analysers involvihg ion-selective electrodes. The author thanks Dr.H. Hughes, Head of the Chemical Services Section at the Teesside Research Centre of British Steel Corporation for his interest and constant encouragement throughout the work and in preparation of this paper. References 1. 2. 3. 4. 5 . Rechnitz, G. A., Chem. Engng, June 1967, 146. Cornish, D. C., Process Engng, October 1973, 110. Frant, M. S., Ross, J . W., jun., and Riseman, J.H., Analyt. Chem., 1972, 44, 2227. Hofton, M. E., Envir. Sci. Technol., in the press. “Analysis of Raw, Potable and Waste Waters,” H.M. Stationery Office, London, 1972, p. 140. axemias in riiiuenxs J. P. Dawson and G. A. Best Clyde Rivcr Puri$cation Board, Murray Road, East Kilbride, Glasgow When the new Control of Pollution Act 1974 comes into force, all discharge into coastal waters will come under the control of the appropriate Water Authority or River Purification Board.The majority of these discharges are of untreated or partially treated sewage and312 NEW TECHNIQUES IN ENVIRONMENTAL ANALYSIS Proc. Analyt. Div. Chem. SOC. there is an increasing need to protect coastal waters and beaches from contamination by these discharges. The usual methods for monitoring the movement of sewage discharged into the sea are either to add a tracer, such as a radioactive material or a fluoresent dye, to the sewage or to use a constituent of the sewage, such as faecal bacteria, ammonia or biodegradable organic matter, as an internal tracer.All of these methods suffer from some drawback such as lack of specificity or sensitivity, the need for expensive monitoring instruments or for rapid analysis before decay.We have been investigating the use of a steroid, coprostanol, as an internal tracer for faecal contamination in water. Coprostanol is one of the main sterols excreted by higher animals and is formed by the biohydrogenation of cholesterol. H db Cholesterol Coprostanol Each person-excretes approximately 1.5 g of coprostanol daily and when this is diluted by waste water from homes and industry the concentration found in crude sewage is about 500 pg 1-l.Method 6f Analysis The method used was mainly that proposed by Murtaugh and Bunch1 and involves the following procedures: (l), extraction of sterols with hexane ; (2), saponification in order to hydrolyse esters to the free sterols; (3), clean-up of the extract by means of thin-layer chromatography ; and (4), determination of the sterols as trimethylsilyl derivatives using gas - liquid chromatography. The recommended extraction procedure gave a good recovery and reproducibility for spiked samples.The saponification step was time consuming and gave rise to poor recoveries and inconsistent results.However, as about 90 per cent. of the sterols present in faeces are in the unconjugated, form,2 the saponification step was omitted. The thin-layer chromato- graphic clean-up procedure of Murtaugh and Bunch was found to be much more efficient than acetonitrile partition2 or column chromatography,3 as proposed by other workers. The spots on the thin-layer chromatographic plates were made visible by spraying with Rhodamine 6G rather than by treating them with molybdophosphoric acid followed by heating for colour development.At the start of the investigation, trimethylsilyl ether derivatives were prepared prior to separation by means of gas - liquid chromatography but subsequent work by Bunch4 showed that satisfactory separation could be obtained by using free sterols and his procedure was adopted for later surveys.The total analysis time is approximately 4 h per sample but several samples can be processed at the same time. Freshwater Surveys In order to determine the effect of sewage treatment processes on the steroids in sewage, a number of samples were taken at different sewage works at various stages of treatment. The results of some of the surveys are given in Table I and show that the reduction in the concentration of coprostanol as a result of sewage treatment is similar to that for the conven- tional pollution parameters. The concentration of sterols in a stream receiving a sewage works’ effluent was investigated by taking 2-1 samples upstream and downstream of the discharge point and analysing them for cholesterol and coprostanol.The results of The results obtained are shown in Table 11.December, 1975 NEW TECHNIQUES I N ENVIRONMENTAL ANALYSIS 313 TABLE I CONCENTRATION OF COPROSTANOL AND OTHER POLLUTION PARAMETERS IN CRUDE SEWAGE AND THE PERCENTAGE REDUCTION RESULTING FROM SEWAGE TREATMENT %lassford SPW 7- Per- centage Parameters Value reduction Coprostanol/pg 1-1 .. . . .. 1200 93 5-d Biochemical oxygen demand/mg 1-1 280 91 Suspended solids/mg 1-1 . . .. 410 88 Chemical oxygen demand/mg 1-1 . . 830 84 Chapelton SPW T - L 7 Per- centage Value reduction 155 80 60 88 135 73 57 74 Glespin SPW -7 Value reduction Per- centage 550 79 215 80 224 77 70 40 the survey show that there is a gradual reduction in the concentration of coprostanol with increasing distance from the sewage outfall.The same trend is not found for cholesterol as the upstream sample already contained cholesterol, probably originating from farm drainage. TABLE I1 CONCENTRATION OF STEROLS IN A STREAM RECEIVING A SEWAGE EFFLUENT Sample point Coprostanol/pg 1-1 Cholesterol/pg 1-1 Upstream of sewage outfall . . . . <0.1 1.03 60 m Downstream . . . . . . 1.25 1.20 700 m Downstream .. . . .. 1.03 1-55 1600 m Downstream . . .. 0.25 1.33 Marine Surveys The value of coprostanol as a tracer for faecal pollution in the sea was assessed at two sites: ( a ) , a large sewage works discharging settled sewage into the Clyde estuary; and (b), a small sewage outfall from the village of Inverkip which discharges macerated sewage into the Firth of Clyde. (a).Dalmuir Sewage Works Survey Two-litre samples of surface water were taken at increasing distances from the outfall and analysed for sterols and for total coliforms in order to compare the two techniques. The results in Table I11 and Fig. 1 show a number of features: (l), the advantage of coprostanol over cholesterol as a tracer; (2), the greater variability of coliform counts when compared with steroid analysis ; (3), the rapid dilution of steroids in the estuary, particularly downstream of point 8, as a result of the inflow of the River Leven; (4), the steroids and coliforms were detected in the surface water over 20 km from the sewage outfall.TABLE I11 CONCENTRATION OF COPROSTANOL, CHOLESTEROL AND TOTAL COLIFORMS IN THE CLYDE ESTUARY Sample point Coprc 1. 0.88 km upstream .. . . 2. 0.44 km upstream . . . . 3. At outfall . . . . .. 4. 0.54 km downstream . . 5. 1.60 km downstream . . 6. 3.60 km downstream .. 7. 7-20 km downstream . . 8. 9-20 km downstream .. 9. 12-00 km downstream . . 10. 14.00 km downstream . . 11. 16.00 km downstream . . 12. 17.00 km downstream .. 13. 19.80 km downstream .. 14. 20.80 km downstream .. Dalmuir Sewage Works effluent . . istanol/pg 1-1 12.3 11.0 47.5 8.8 7.8 3-8 3.6 3.2 0.7 0.3 (0.1 <0.1 <om1 <om1 232 Cholesterol/pg 1-1 4.8 5-0 12-5 3-5 2.3 1.3 2.0 1.1 0.8 1.0 0.2 <0*1 <0.1 (0.1 76 Total coliforms, x 1000 per 100 ml 1600 900 5500 130 560 225 90 90 3.5 2.5 1.7 3.0 1-7 0.5 -314 Sewage Works. NEW TECHNIQUES IN ENVIRONMENTAL ANALYSIS Proc. Analyt.Div. Chem. Soc. Samples from points 1 and 2 were already contaminated with effluent from the Shieldhall 50 c I m 3. - 3 4 0 - 2 x 0 30- Lc C 0 .- +J 6000 5000 0 4000 X 2 3000 c. E 8 B 2000 - - I- 1000 0 - 0 - Total coliforms - Coprostanol - Cholesterol Sample number 5 10 15 Distance dcwnstream/km 20 Fig. 1. The concentration of coprostanol, cholesterol and total coliforms in the Clyde estuary downstream of Dalmuir sewage disposal works.(b) . Two-litre samples of sea water were collected from the beaches on the flood tide at a number of selected points up to 2.6 km on either side of the marine outfall. The samples were analysed for coprostanol, cholesterol and faecal coliforms and the results obtained are shown in Table IV. Evidence of faecal contamination of the sea water has been provided by both techniques but it is difficult to arrive at a precise comparison between the two pollution parameters because of the variability of the results.TABLE IV Inverkip Marine Outfall survey CONCENTRATION OF COPROSTANOL, CHOLESTEROL AND FAECAL COLIFORMS IN SEA WATER ADJACENT TO THE INVERKIP MARINE OUTFALL Sample point Coprostanol/pg 1-1 Cholesterol/pg 1-1 1.2.55 km North. . . . . . 0.12 0.12 2. 1.80 km North. . . . .. 0.36 0-40 3. 1-40 km North. . . . .. 0.70 0.90 4. 1-00 km North. . . . . . 0.27 0-40 5. 0.78 km North. . . . . . 0.50 0.40 6. 0.55 km North. . .. .. 0.33 0.42 7. 0.18 km North. . .. .. 2.44 1.06 8. Inverkip outfall . . .. 620 300 9. 0.15 km South. . . . .. 0.20 0.75 10. 0.70 km South.. . . . . 1.10 1.80 11.1.00 km South. . . . .. 0.35 1.50 12. 1-20 km South.. .. .. 0.40 0.90 13. 2.30 km South. . .. .. 0.50 0.70 14. 2-60 km South.. .. .. 0.32 1-55 Faecal coliforms/ 1000 per 100 nil 0.8 1.5 0-7 0.8 5.8 3.1 57.5 0.5 17.0 1.3 0-5 1.1 3.5 4550 In order to check the significance of the results for samples taken some distances from a sewage outfall, 5-1 samples of sea water were taken from various remote areas on the WestDecember, 1975 NEW TECHNIQUES I N ENVIRONMENTAL ANALYSIS 315 coast of Scotland and analysed for sterols by using the method described earlier.For all of the samples collected, a small peak was found on the recorder trace obtained with gas - liquid chromatography which coincided with the position for coprostanol and was equivalent to -0.2 pg 1-l.It is not yet known whether this is coprostanol and thus represents the back- ground concentration of this steroid due to the discharge of sewage into the sea, or whether it is a naturally occurring plant steroid with the same retention time as coprostanol. The sur- prisingly high value for coprostanol in these marine background samples as compared with those obtained for samples from the lower Clyde estuary cannot as yet be explained.Further work is in progress to elucidate this phenomenon. Conclusions Our work so far has shown that coprostanol is a good indicator of faecal pollution in fresh and saline waters. Although the analysis time is considerably greater than for faecal bacteria counting, the samples do not require immediate analysis and the results obtained are less subject to error.References 1. 2. 3. 4. Murtaugh, J . J., and Bunch, R. L., J . Wat. Pollut. Control Fed., 1967, 29, 404. Kirchmer, C. J., Ph.D. Thesis, University of Florida, 1971. Kussmaul, H., and Muhle, A., Vortragsveroffentlichungen, Haus der Technik e.V., Essen, 1971, Tabak, M. H., Bloomhuff, R. N., and Bunch, R. L., Deu. Ind. Microbiol., 1972, 13, 296. 283, 52.Variability in the Chemical Composition of Sea Water E. I. Hamilton Institute for Marine Environmental Research, 67/79 Citadel Road, Plymouth, PL 1 3DH Variability in the inorganic and organic composition of sea water can be attributed to factors such as distance from land, local and regional water circulation patterns, depth of water and biological activity.Within limits, large-scale programmes of monitoring and surveillance are capable of describing chemical variability in terms of space and time. Small-scale studies in the field and laboratory are capable of identifying the chemical form and activity of dissolved and particulate materials in the sea, as well as interactions between living and non- living constituents. The sea may be considered as a large “bucket” stirred by the ocean currents, receiving inputs from the land and air and with outputs through bottom deposition and aerial transport forming part of the natural hydrogeological cycle.Owing to the large volume of the seas, the major chemical systems are not subject to rapid changes, although in some areas, such as inshore waters and bays, changes are directly related to continental processes.Fresh water run-off from continental areas is chemically (and biologically) very different from sea water and when such waters enter the sea very rapid chemical changes occur at a salinity of about 2 4 per cent. As a result, precipitation, adsorp- tion, desorption and solution processes take place, depending upon whether or not the chemical species act in a conservative or non-conservative manner.A predominant process involves precipitation and aggregation of materials associated with a wide variety of surface exchange processes ; as materials travel deeper and further from land, solution and sedimentation pro- cesses take place. Superimposed upon non-living chemical systems, biological activity exerts a profound effect on the bulk chemical composition of the seas because of the presence of large numbers of small animals and plants together with their excretory products.Most biological materials are subject to major spatial and temporal variability ranging from diurnal and seasonal cycles of activity to annual and long-term trends. Within the ocean the residence time of materials ranges from seconds to several thousand years.Of the dissolved elements present in the seas the most significant contributors to mass are hydrogen, oxygen, chlorine, sodium, magnesium, sulphur, calcium, potassium and bromine, while about 30 other elements are present at concentrations of less than about 10-4 mg 1-l. The sea is a buffered medium and the chemical elements are present in a wide variety of316 NEW TECHNIQUES IN ENVIRONMENTAL ANALYSIS Proc.AnaZyt. Div. Chem. Soc. chemical forms; for instance, in sea water, depending upon pH, zinc can be present in at least ten different chemical forms. In biological studies concerned with uptake of the chemical elements from the marine environment, it is essential to consider the significance of chemical form.Such information is also required in the laboratory in order to select the most appro- priate reagent for extracting the elements, and when using radionuclides to consider transfer kinetics to ensure that true mixing occurs between the chemical form of the tracer and that of the element present in a sample. The sea can also be considered as a rather thin soup, the particulate matter content of which varies seasonally.In order to sample suspended solid phases, various methods are available, ranging from the use of nets to laboratory filtration techniques. A standard method for removing fine particles is vacuum filtration using 0.45-pm filter-paper; in turbid waters it is often necessary to sample 50-1 volumes of sea water, but in practice it is often only possible to filter 100-200 ml before the pores of the filter-paper become clogged. This problem can be partly overcome by pressure filtration, even with a final pass filter of 0.2 pm.However, even when using fine filters, some solids, coagulated macro-molecules and colloids are not retained by the filtering media. Further separations, however, can be achieved by using ultra- filtration techniques.The extent to which elements and compounds are partitioned between solids and dissolved phases varies considerably; in the open sea there is considerably more non-dialysable zinc than in near-shore waters, possibly reflecting the presence in the open sea of zinc bound into biological materials such as protein and lipids. Relative to sea water, micro-organisms (such as bacteria and plankton) present in marine environments often contain high concentrations of the chemical elements, which poses a problem of sampling for studies concerned with identifying those elements present in the dis- solved state in the sea.Most methods of filtration result in the disintegration of these delicate organisms and the release of body fluids. A similar problem arises when the abund- ance of elements in the organic phases of planktonic organisms is sought because of the presence (particularly in filter feeders) of inorganic particulate matter entrained in their external structure or within the gut.One of the most difficult areas of the sea to sample is the air - sea interface, at which many elements and compounds, relative to sea water, may become enriched; a possible solution rests in controlled freezing of the surface layer to a depth of a few micrometres by impaction with a liquid nitrogen cooled collector.In several areas of the world the contributions of aerial inputs for elements and compounds is equal to or greater than that provided by continental run-off. Many methods are available for bulk assay of elements in sea water and elegant techniques exist for the separation of specific organic compounds.However, increased attention has to be paid to the chemical forms of materials present in the sea, of which organic bound species are important in relation to availability and utilisation by marine organisms. There are many techniques, such as those for comparing levels of elements before and after total oxidation, partial oxidation (for example, irradiation with ultraviolet light, peroxodisulphuric acid) or selective extraction.As many elements and compounds are present in trace amounts, great care is required in sampling both at sea (most ships are abundant sources of paint flakes, oil and grease) and in the laboratory. Modern instrumentation, when combined with techniques for enriching elements and compounds, usually gives adequate detection limits, but the contamination of samples is often ignored as a major source of error when determining small amounts or small differences in levels of the elements and compounds present in the marine environment.In future our knowledge of chemical processes taking place in the marine environment will possibly require improved techniques rather than improved instrument ation.For inorganic compounds, inductively coupled plasma sources coupled to optical spectrometers provide simultaneous direct assay for up to about 40 elements in sea water and are likely to become important tools of marine chemists because of sensitivity and freedom from matrix effects. At the other extreme very simple colorimetric field measurements are likely to replace many tedious laboratory measurements for several elements and provide, at low cost, true field synoptic surveys.In the laboratory significant advances can be expected in identifying metabolic pathways and sites of retention of elements and compounds in marine material of interest to pollution studies; radiotracers are proving to be useful in such work.Once more, instruments are available, but techniques are lacking or have been only partially developed. In attempting to understand how total marine ecosystems operate and the constraints thatDecember, 1975 NEW TECHNIQUES I N ENVIRONMENTAL ANALYSIS 317 are likely to impair their performance, particular attention has to be paid to estuaries and inshore waters, which are subjected to the highest load of contaminants and pollutants; it is in such waters that detrimental or beneficial effects are likely to be first detected.However, it must be remembered that the sea is a dynamic and highly variable system in which con- siderable changes occur, evidence for which is provided by the geological record. Multiple Pollutant Monitoring Using Spectroscopic and Gas-chromatographic Methods in a Mobile Laboratory P.A. Hollingdale-Smith Chemical Defence Establishment, Povton Down, Salisbuvy, Wiltshive, SP4 0 J Q . Work involving measurements of atmospheric pollution has been carried out at the Chemical Defence Establishment for many years, and many of the earlier booklets in the series “Methods for the Detection of Toxic Vapours in Air” were based on methods developed at Porton Down.As the detection sensitivities of analytical methods are improved, so there is increased likelihood of interference from gases other than the one for which the method is intended. It is obviously necessary that any detection system should respond to the compounds being sought, without responding to any other compound which might occur as a normal con- stituent of the atmosphere in which the detection system would have to operate, and therefore prior knowledge of the nature and concentrations of these normal constituents is important. Literature surveys showed that, contrary to expectations, the vast majority of atmospheric pollution surveys covered only a very small selection of compounds and that there had been no attempts at anything approaching a “total” survey of atmospheric pollution in a particular environment.For this type of survey a virtually universal method for the detection and measurement of pollutants is needed and the only practical one available for gaseous pollutants was infrared spectroscopy, using a sufficiently long absorption path to provide the required sensitivity.As might be expected with a “universal” analytical technique it falls short of the optimum in some instances and the detection sensitivity attainable varies for different compounds. A number of surveys, mostly in military or naval environments, were carried out using long- path infrared spectroscopy, but the scope was limited by the time involved in transporting samples for analysis, because the longer the time lapse between sampling and analysis the less chance there is of the results accurately reflecting the concentrations in the air at the time of sampling.It was decided that these limitations could best be overcome by setting up a mobile pollution monitoring unit. This was converted in order to house the infrared equipment, a gas chromatograph and, initially, a small quadrupole mass spectrometer.Provision was also made for gas supplies, a recording wind vane and anemo- meter, particulate sampling equipment, a mobile generator, and a toilet compartment. The air from which samples are taken for the analysis of gaseous pollutants is drawn from above roof level through a vertically mounted glass duct.A Vent-axia type fan, mounted below floor level, pulls air through this duct at a rate of 90 m3 h-l, and sampling probes can be inserted so as to take samples from the centre of the air stream directly into the long-path gas cell, the quadrupole mass spectrometer, or on to an adsorbent for subsequent analysis by gas chromatography. In instances where analyses of air not directly accessible to the mobile laboratory are required, samples are taken by using the equipment devised for this type of work before the laboratory was commissioned.This equipment comprises sample bags of about 60-1 capacity made from a 3-ply laminate of polyester, aluminium foil and polythene, which are inflated by placing them inside a sealable Perspex box, with the sample bag inlet protruding, and then exhausting the air from the box by means of a suitable pump.This method avoids the possibility of contaminating the sample and of losses of trace components by passing it through a pump. The infrared equipment consists of a Perkin-Elmer, Model 221, Spectrophotometer fitted with a pair of multi-reflection “White” type gas cells used at a path length of 40 m.Ordinate scale expansion is fitted to the instrument, giving effective path lengths of up to 800m, The vehicle used was an RAF communications trailer.318 NEW TECHNIQUES IN ENVIRONMENTAL ANALYSIS Proc. Analyt. Div. Chem. SOC. which is useful for scanning very weak absorption bands. The cells are evacuated by means of a single-stage rotary vacuum pump to a pressure of about 0.1 torr, which has proved adequate for normal purposes.Typical detection sensitivities attainable with this equipment are shown in Table I. When using a path length of 40 m the absorption bands due to atmos- pheric water vapour and carbon dioxide mask considerable portions of the spectrum and as it is not possible to remove the water vapour or carbon dioxide from the sample without the risk of removing trace amounts of other compounds, optical compensation methods have been used to overcome this interference.Identification of compounds is carried out in much the same way as for liquids and solids, bearing in mind that one is dealing almost invariably with a mixture, and often with components present at such concentrations that only the stronger bands in the spectrum can be seen.Quantitative analysis entails the preparation of calibration graphs rather than the determination of absorptivities, as Beer’s law is obeyed only for low absorbance values for most of the gases examined, and the deviations can be large. It is also advisable to calibrate the system for losses on the cell walls and in the sample bag if one is used.TABLE I SENSITIVITIES OBTAINABLE BY USE OF INFRARED SPECTROSCOPY Compound Minimum detectable concentration,-p.p.m. CZHZ 0.004 CCl,F, 0.007 CH,Cl, 0.03 HCN 0.03 CHCl, 0.0 1 0.1 0.8 50 3 H2S The quadrupole mass spectrometer is a UTI, Model lOOC, capable of scanning to m/e 300. It is interfaced to the atmosphere by a Llewellyn-type inlet system,l the silicone-rubber membrane of which provides a concentration factor relative to oxygen and nitrogen of about 500 to 1 for organic molecules, because of their higher solubility in the rubber.Owing to inherent difficulties in analysing mass spectra of mixtures, particularly when the components of interest are present at concentrations of the order of 1 p.p.m. it has not proved useful as a general monitoring instrument in the same way as the equipment for infrared spectroscopy.Its most useful application appears to be as a monitor for one or two compounds by measuring sequentially the intensities of selected characteristic m/e fragments. The instrument is at present fitted with a three-peak scanning system with a sequencing time of 1 s per channel. Its sensitivity to materials such as halogenated hydrocarbons is of the order of 0-1 p.p.m.The gas-chromatographic equipment comprises a Perkin-Elmer, Model F1 1 , gas chromato- graph fitted with stacked-flame ionisation and thermionic detectors and, via a stream splitter, an electron-capture detector. While it is not possible to identify compounds purely on the basis of retention times on a single column, the relative responses of the multiple detectors coupled with gas-chromatographic conditions which have been planned so that a relatively small number of compounds are eluted, enable some identifications to be made.This equip- ment has been used to measure atmospheric levels of halogenated hydrocarbons, which levels are normally such that it is necessary to concentrate the sample on a suitable adsorbent, in this instance cooled charcoal. The collected sample is transferred to the gas chromatograph by flash heating the charcoal after connecting the sampler directly to the injection port.Particulate sampling is carried out by using a Charles Austen Duplex pump to pull air through a Whatman No. 44 filter-paper, the sampler being mounted above roof level. The sampling rate is 40 1 min-l and each sample is taken for a period of 7 d, the total sample volume being about 500 m3.These samples are returned to the Chemical Defence Establish- ment for analysis for selected heavy metals by use of emission spectroscopy. Results from infrared and gas-chromatographic analyses are usually presented as a function of time or wind speed and direction. Fig.1 shows a typical wind rose, displaying the correla- tion of concentrations of Freon 12, a common refrigerant, with wind directions. This was from a survey conducted in Port Talbot.December, 1975 NEW TECHNIQUES I N ENVIRONMENTAL ANALYSIS N t 2.2 x 10-5 2.2 x 10-5 1.2 x 10-~ 1.1 x lod5 \ 1 7.8 X 10-6 1.1 x 10-5 8.7 X N.D. 1.4 x 10-5 2.2 x 10- 5 319 1.5 x 10-5 1.4 x 10-5 7.8 X I 1.3 X 2.0 x 10-5 Fig.1. Diflnorodichloromethane wind rose, N.D., with concentrations in parts per million. not detected. Table I1 shows the results of particulate analyses, some from the survey referred to above and others from a survey on Salisbury Plain. TABLE I1 RESULTS OF PARTICULATE ANALYSES Concentration range/ng m-3 A I I Metal Salisbury Plain Port Talbot Pb 10-280 30-670 Cr <0-04-0*2 < 0.04-0.3 V 0.04-50 0.1-1.3 Cd <0*04-1.0 0.3-3.3 Fe 0.8-1 750 700-8300 Zn 2-100 10- 1700 Reference 1.Collins, G. G., and Utley, D., Chemy. Ind., 1972, 84. Carbon Furnace Atomic-absorption Analysis of Atmospheric Particulates J. M. Ottaway and D. C. Hough Department of Pure and Applied Chemistry,. University of Strathclyde, Cathedral Street, Glasgow, G1 1XL The development of the carbon furnace atomic-absorption technique for the analysis of atmospheric particulates was carried out for and in close collaboration with the Ravenscraig Works of the British Steel Corporation in Motherwell and the work described is specifically related to this environment.In a steelworks, dust is generated at many stages in the iron- and steel-making processes and the total emission load is of considerable concern to the works, the Alkali Inspectorate and the general public.At each place in the works where dust is created drastic efforts are made to reduce the amount of atmospheric emission by, for instance, electrostatic precipitation or gas scrubbing with venturi jets of water. However, there is obviously a need to monitor the total dust load and its composition in order to obtain some idea of the total environmental emission of different elements.Considering the composition of dusts emitted from steelworks and the known toxicity of particular elements, it was considered desirable to monitor fifteen elements, i.e., arsenic,320 NEW TECHNIQUES IN ENVIRONMENTAL ANALYSIS Proc. AaaZyt. Div.Chervt. SOC. beryllium, cadmium, cobalt, chromium, copper, fluorine, mercury, manganese, molybdenum, nickel, lead, tin, vanadium and zinc. The residual dust emissions are passed into the atmos- phere via chimney stacks at different parts of the factory and it was considered desirable to sample both material passing through the various chimneys and also the specific particulate load at different parts of the factory and neighbouring urban areas.As the amount of sample that could be collected at most sites would be small and the levels of many elements in such samples very low, a technique with high sensitivity for a wide range of elements was required and carbon furnace atomic-absorption was selected and is suitable for all the required elements except fluorine and mercury.In the steelworks the main sources of dust emissions are the sinter plant, the open-hearth steel-making furnace and the basic oxygen steel-making furnaces. In the sinter plant there are two main sources of dust. The mixture of iron ore, coke and limestone is fused and fed by a hopper on to a moving bed where air is drawn through it. The dust carried away by the waste gas is reduced by electrostatic precipitators and the residue is passed out of the waste- gas chimney.The fused sinter is subsequently cooled and crushed and this generates con- siderable dust, which is reduced and passed out of the de-dust gas chimney stack. Each open- hearth and basic oxygen steel-making furnace has its own chimney stack and emissions from these contain larger amounts of the more volatile elements released during the steel-making process.Each chimney is sampled isokinetically at four to eight points across the width of the chimney. The flow-rate of gas in the chimney varies across it, i.e., it is reduced towards the walls. It is necessary to draw gas into the sampler at the same rate as the gas flow at the particular point in the chimney in order to avoid streaming and an unrepresentative sample. The flow-rate is measured at each position with a pitot tube and temperature and pressure corrections are applied before the cyclone probe sampler is placed in position and sample pumped through it at the correct flow-rate.Each position is sampled for 3-5 min and the total dust sample from a chimney collected in pre-weighed hoppers.Sample size varied be- tween 0.2 and 2 g, most samples being near the lower end of this range. Samples are dissolved in a procedure involving hydrochloric, nitric and perchloric acids. Small residues of silica are left but these contain no measurable amounts of the elements of interest. This single solution is used for the determination of 12 elements, although different dilutions are sometimes re- quired for the range of concentrations found, i.e., 0.0001-9 per cent.Analysis is carried out using a Perkin-Elmer HGA 74 carbon furnace mounted in a Model 306 atomic-absorption spectrometer and coupled to a PE 56 strip-chart recorder. Optimum conditions for each element have been identified and a check for major interferences carried out. Samples are mainly iron(II1) oxide and standards are prepared with a similar iron content. Results have been compared with results obtained by various alternative analytical techniques, such as flame atomic absorption for major constituents such as zinc and manganese and atomic fluorescence for cadmium. Acceptable agreement was obtained. It has been shown1 that oxide or oxyanion solution media are advantageous for application to the carbon furnace method of atomisation as they give accurate and reproducible signals. One attractive possibility appeared to be the atomisation of the solid oxide sample by direct addition to the furnace, thus saving on dissolution time. Some acceptable results were obtained using sample masses of between 0.2 and 1 mg, for example, a relative standard deviation of 5.1 per cent. was obtained for lead at the 0.0024 per cent. level in one sample. In general, however, the need for careful grinding so as to reduce the effect of inhomogeneity on a sample size of 0-2-1 mg, the time consumed in weighing this amount of sample, and the need for a separate weighing for each duplicate analysis and for each element make the use of solid sampling relatively unattractive. A high-volume turbine blower mounted on the back of a van is being used to collect atmos- pheric particulate samples from various locations at the works and at the site of the new ore terminal at Hunterston on the Ayrshire coast. Particulates are collected from up to 17 m3 of air in 30 min and sample masses varying between 0-6 and 7 mg are collected on Whatman No. 41 filter-papers. Acceptable results have been obtained to date for zinc, iron, manganese, lead and copper. Multi-element analysis of dust emissions and atmospheric particulates is possible by using carbon furnace atomic-absorption spectrometry with a minimum of sample preparation and despite the small sample size and low level of several important constituents. With the These are dissolved in nitric and perchloric acids.DeCembef', 1975 APPLICATION OF COMPUTERS TO AUTOMATIC ANALYSIS 32 1 present frequency of sampling and number of sample points, this technique adequately satis- fies the analytical requirements. Full details of this work will be published elsewhere. Reference 1. Ottaway, J. M., Proc. Analyt. Div. Clzem. SOC., 1975, 12, 176.

ISSN:0306-1396    

DOI:10.1039/AD9751200308

出版商:RSC    

年代:1975

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DeC&VZbU', 1975 APPLICATION OF COMPUTERS TO AUTOMATIC ANALYSIS 32 1 Application of Computers, Particularly Microprocessors, to Automatic Analytical Instrumentation The following is a summary of one of the papers presented at a Meeting of the Automatic Methods Group held on February 26th, 1975, and reported in the March issue of Proceedings (Pa 76). A Data-processing System for Quantitative Nuclear Magnetic Resonance Measurements W.Bunting, F. Morley, I. K. O'Neil and P. B. Stockwell Department of Industry, Laboratory of the Government Chemist, Cornwall House, Stanzford Street, London, SE1 DNQ Quantitative procedures for the analysis of many materials, particularly pharmaceuticals, by means of nuclear magnetic resonance spectrometry have been developed at this Laboratory. The route chosen in any organisation for solving data-processing problems of this nature is for the most part determined by the level of expertise available, the availability of a commercial company which can undertake the problem and also by the economics involved.Computer support in the Laboratory is provided by a small group working within the Automatic Methods and Computing divisi0n.l The data-processing needs have for the most part been tackled by using a Remote Batch Terminal coupled in an off-line manner to several large bureau-operated machines.However, as there is increasing demand for on-line data capture and subsequent data processing an in-house facility based on a Rank Xerox RX530 computer system is currently being installed. With this computing power available the reasons for developing a micro- processor based solution must be substantiated.Microprocessor chips are rapidly decreasing in price and it has been predicted that they will be available for as little as El00 in the next few years. As a consequence they are being in- corporated into many analytical instruments, for example, gas chromatographs.They not only control the instrument, i e . , gas flows, oven temperatures, etc., but are also capable of providing data-processing facilities in a similar manner to electronic integrators. In labora- tories such as this, where additional post processing and reporting are prime functions, it is important to couple this new range of instruments with the associated microprocessors to our in-house computer facility, and therefore an understanding of the intricacies of microprocessors is important. In addition to this requirement there are several other possible applications for micro- processors in the laboratory, for example, as data concentrators collecting data on-line from a group of instruments, carrying out some data correction and then transmitting the data at a convenient time over a teletype line to the central site.Hardwired control systems used on automatic instruments are often difficult or impossible to modify if the analytical requirements change. In other instances the hardwire logic places rigid constraints on the analyst with regard to the method of operation of the instrument. An example of this is the automatic beer analyser, essentially a three-channel analyser measuring alcohol, acid and sugar content.This method of analysis requires that the peaks for each analyte appear in defined order and that a rigid sampling plan should be used. Automatic instruments are becoming increasingly322 APPLICATION OF COMPUTERS TO AUTOMATIC ANALYSIS Proc. AnaZyt. Div. Chem. soc. complex and hardware control becomes extremely involved.Microprocessor systems over- come this problem particularly where control parameters require updating to account for a change in instrument performance. For these reasons it was important to gain experience with microprocessors. Quantitative nuclear magnetic resonance spectrometry has a number of advantages over other analytical techniques : it involves little or no sample preparation, has better specificity and often multiple peaks are available; it is inherently a quantitative technique and primary standards can be used.A number of these standards have been evaluated at the Laboratory.2 For quantitative measurements an internal standard is added to provide a resonant peak close to the sample reference peak but which does not interfere with or overlap it.It must be added to the sample and not undergo change in its chemical composition. The percentage purity can then be calculated from the equation Mass of standard Area for X PEW of X PEW of standard' Area for standard Mass of X Percentage purity = where PEW is the proton equivalent mass, for example, PEW of X = Relative molecular mass of sample Number of protons in sample Single-scan measurements of the areas show the normal random errors associated with the technique but the relative precision of the method can be considerably improved by multiple scanning and by providing an effective method of integration.The data-processing system should control the instrument scanning mechanism, measure areas of up to six peaks or groups of peaks, average the area for a selected number of scans and calculate and print the percentage purity.The instrument development has been carried out in two phases, firstly the construction and evaluation of a hardware integration unit and secondly the interfacing and programming of the microprocessor control system. 1ntegration3s4 Several electronic integrators were evaluated but in each instance the high slew-rate peaks generated by the nuclear magnetic resonance spectrometer were not integrated correctly.Treating the peaks by software designed for gas chromatography also has limitations, as the peaks must be smooth for correct evaluation. The technique developed integrates the total area above a base-line threshold for defined zones, set by the operator, which encompass the peaks of interest.The signal from the spectrometer is fed to both the chart recorder on the instrument and the integrator system, amplified within the integrator to give a range of 0-10 V, and then passed to a voltage to frequency converter and thence to a counter store. The beginning and end of each zone is controlled as follows : a linear potentiometer fixed to the instrument's chart recorder is supplied with a fixed voltage and a potentiometer wiper is fixed to the pen carriage ; as the carriage traverses the chart the wiper voltage varies linearly with its position.The wiper voltage is compared electronically with the voltage from 12 zone poten- tiometers, these set by the operator to give the correct zone start and stop positions.The out- puts from the comparators are used to start and stop the counter store, which will then indicate the relative areas of the zones. The integrator is set up when the nuclear magnetic resonance signal is on base-line and the voltage to frequency counter does not record any counts. The voltage to frequency conversion provides equivalent resolution to a 13 bit A/D convertor.Control System A series of thumbwheel switches are provided with which to enter parameters into the system, k, the mass of sample and standard, the proton equivalent mass, the number of scans required and the zone number used for standardisation. The microprocessor is interfaced to the integrator and to a series of displays which indicate the average zone counts stored in specific registers of the processor and the scan number.At the start of a run all registers are zeroed and the recorder scan mechanism operated by the A block diagram of the microprocessor system under development is shown in Fig. 1.December, 1975 CONFERENCES AND MEETINGS Switch for Start or stop number of - scan drive scans required mechanism 323 signal Digital integrator display Sample mass (rng) switch 7r AL 1 Standard mass (mgl switch Proton -- microprocessor until the preset number of scans is reached.hibited as the pen drive is reversed prior to the start of a scan. percentage purity is calculated and output on a terminal, for example, a teletype. ment is now well under way. The counter mechanism is in- On completion of scanning the The first stage of the project has been successfully completed and the microprocessor develop- 7r Average area References 1. Stockwell, P. B., and Telford, I., Chrornatographia, 1974, 7, 465. 2. “Report of the Government Chemist 1974,” H.M. Stationery Office, London, 1975. 3. Bunting, W., MSG Thesis, Polytechnic of Central London. 4. British Patent, Provisional Application 4740/74. equivalent L - ineachzone ‘ mass switch. for sample display mass switch I dent i f i ca t i o n of standard L channel switch 1 Number of scans done display Processor with front-panel control switches IMP-1EC 7 Te I ety pe ~ output

ISSN:0306-1396    

DOI:10.1039/AD9751200321

出版商:RSC    

年代:1975

数据来源: RSC

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December, 1975 Conferences and CONFERENCES AND MEETINGS Meetings South East Region Meeting January 27, 1976, London The South East Region of the Analytical Division will be holding its first Annual General Meeting a t 6.15 p.m. on January 27th, 1976, in the Linnean Society Meeting Rooms, Bur- lington House, Piccadilly, London, W. l . The Annual General Meeting will be followed, at approximately 6.30 p.m., with a talk by Peter Sand, Head of Research of the Con- sumers’ Association, publishers of Which ?, on “Research and Testing for the Consumer.” Elements of Analytical Instrument Electronics 323 April 1-8, 1976, Guildford A workshop course on the above topic is to be held at the University of Surrey in Guildford.Further information can be obtained from Dr. E. Reid, Wolfson Bioanalytical Centre, University of Surrey, Guildford, Surrey, GU2 5XH. International Symposium on Mass Spectro - metry in Drug Metabolism June 21-23, 1976, Milan This Symposium is being organised by the “Mario Negri” Institute for Pharmacological324 CHEMICAL SOCIETY LIBRARY Proc.Analyt. Div. Chew. SOC. Research and is to be held a t the Institute in Milan, Italy.The application to drug metabolism of topics such as gas chromatography - mass spectro- metry, mass fragmentography, stable isotope measurements, field ionisation, field desorption, chemical ionisation, high-resolution studies, and data acquisition and processing will be covered. In particular, the preferred topics will include : detection and identification of drug metabolites ; mass fragmentography techniques in drug metabolism studies ; and improvements in the methodology of drug metabolite measurements. Invited speakers will present papers and contributed papers are sought. Those wishing to present a communication (approximately 20 min) are requested to submit the title and an abstract of no more than 200 words before February 28th, 1976. Further information from Dr. Alberto Frigerio, Istituto di Riccrche Farmacologiche, “Mario Negri,” Via Eritrea 62 - 20157 Milan, Italy.

ISSN:0306-1396    

DOI:10.1039/AD9751200323

出版商:RSC    

年代:1975

数据来源: RSC

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324 CHEMICAL SOCIETY LIBRARY Proc. Analyt. Div. Clzenz. SOC. Chemical Society Library The following publications of analytical interest have been added to the Library since the last list appeared in Pvoceedings (1975, 12, 260). Electrode Kinetics. J. Albery. Clarendon Press. 1975. Particle Size Measurement. Second Edition. T. Allen. Chapman and Hall. 1975. Analytical Calorimetry. Volume 3.Pro- ceedings of a Symposium of the Division of Analytical Chemistry of the American Chemical Society, Los Angeles, 1974. Edited by Roger S. Porter and Julian F. Johnson. Plenum. 1974. Trace Elements in Fuel. Symposium of the Division of Fuel Chemistry of the American Chemical Society, Chicago, 1974. Edited by Suresh P. Babu. Advances in Chemistry Series, No. 141. ACS. 1975. The Infra-red Spectra of Complex Mole- cules.Volume 1. Third Edition. L. J. Bellamy. Chapman and Hall. 1975. Handbook of Reactive Chemical Hazards : an Indexed Guide to Published Data. L. Bretherick. Butterworths. 1975. The Determination of Vinyl Chloride, a Plant Manual. Edited by W. Thain. Chemical Industries Association. 1974. Applications of High- Speed Liquid Chrom- atography.J. N. Done et al. Wiley. 1974. Vibrational Spectra and Structure. Volume 3. Edited by J. R. Durig. Dekker. 1975. Foundations of Ultracentrifugal Analysis. H. Fujita. Chemical Analysis, Volume 42. Wiley. 1975. Infrared Spectra of Minerals and Related Inorganic Compounds. J. A. Gadsden. Butterworths. 1975. The Techniques of Analytical Chemistry: A Short Historical Survey. H. M. N.H. Irving. H.M. Stationery Office. 1974.Decernbev, 1975 Organic Spectroscopy. W. Kemp. Macmillan. 1975. PUBLICATIONS RECEIVED Molecular Spectroscopy. I. N. Levine. Wiley. 1975. Determination of Gaseous Elements in Metals. Edited by L. M. Melnick et al. Wiley-Inter- science. 1974. Analytical Chemistry of Germanium. Translated from Russian. V. A. Nazarenko. Israel Program for Scientific Translations. 1974. Ultra-Violet and Visible Spectroscopy: Chemical Applications. Third Edition. C. N. R. Rao. Butterworths. 1975. Analysis of Silicones. Edited by A. L. Smith. Wiley. 1974. Registry of Mass Spectral Data. Four volumes. Edited by E. Stenhagen. Wiley. 1974. United States Pharmacopeia. 19th Revision. United States Pharmacopeial Convention, Inc. 1974. The Chemical Analysis of Water: General Principles and Techniques. A. L. Wilson. Society for Analytical Chemistry. 1974. 325 Chemical Phase Analysis. R. S. Young. Griffin. 1974.

ISSN:0306-1396    

DOI:10.1039/AD975120324b

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

Decernbev, 1975 PUBLICATIONS RECEIVED 325 Joint Survey of Pesticide Residues in Foodstuffs sold in England and Wales. 1st January 1972-31st December 1972 (third year). Association of County Councils, Association of Metropolitan Authorities, Association of District Councils and Association of Public Analysts. Pp. 36. Association of Public Analysts: London. 1975. Price k4-75. Publications Received Principles and Techniques of Scanning Electron Microscopy.Biological Applica- tions. Edited by M. A. Hayat. Volume 4. Pp. xx + 230. New York, Cincinnati, Toronto, London and Melbourne : Van Nostrand Reinhold Com- pany. 1975. kll.50. NMR Spectroscopy Using Liquid Crystal Solvents. J. W. Emsleyand J . C. Lindon. Pp. xvi + 367. Oxford, New York, Toronto, Sydney and Braunschweig : Pergamon Press.1975. Price k9.50; $22. Positive Staining for Electron Microscopy. M. A. Hayat. Pp. xxii + 361. New York, Cincinnati, Toronto, London and Melbourne : Van Nostrand Reinhold Company. 1975. Price k13.75. Practical Pharmaceutical Chemistry. Third Edition. A, H. Beckett and J . B. Stenlake. Part 1. General Pharmaceutical Chemistry. Revised by J. B. Stenlake with contributions by W.D. Williams. Pp. x + 370. London: The Athlone Press. 1975. Price Q O . Annual Reports on Analytical Atomic Spectroscopy, Reviewing 1974. Edited by C. Woodward. Volume 4. Pp. xii + 268. London: The Chemical Society. 1975. Price i12. Methane : Proceedings of a One-day Seminar convened by the Intermediate Technology Group at Imperial College, London, October 1974.Compiled by Dr. Leo Pyle and Peter Fraenkel. Pp. iv + 51. London: Intermediate Tech- nology Publications Ltd. 1975. Price 80p. A Guide to International Recommendations on Names and Symbols for Quantities and on Units of Measurement. D. Armstrong Lowe. Progress in Standardiz- ation: 2. Pp. 314. Geneva: World Health Organization. 1975. Price SwFr48. Available through H. M. Stationery Office, London.International Commission for Uniform Methods of Sugar Analysis. Report of the Proceedings of the 16th Session held in Ankara, 1974. Pp. xviii + 383. Peterborough : ICUMSA. 1975. Price L G . Aldehydes-Photometric Analysis. Volumes 1 and 2. Eugene Sawicki and Carole R. Sawiclti. The Analysis of Organic Materials, Number 9. Volume 1: pp. xxviii + 283. Volume 2 : pp.xiv + 344. London, New York and San Francisco : Academic Press. 1975. Price : Volume 1, kl0.50; Volume 2, &10.80.326 PUBLICATIONS RECEIVED Proc. Analyt. Div. Chem. SOC. The Role of Trace Metals in Petroleum. Edited by T. F. Yen. Pp. viii + 221. Michigan: Ann Arbor Science Publishers Inc. 1975. Price ,610-60. Handbook of Spectroscopy. Edited by J. W. Robinson. Volume 1.Pp. xii + 913. Cleveland, Ohio: CRC Press. 1974. Price ,626. Journal of Hazardous Materials. Editors, F. S. Feates and T. A. Kantyka. Volume 1, No. 1, September, 1975. Pp. iv + 96. Amsterdam : Elsevier Scientific Publishing Company. 1975. Subscription for Volume 1 in 4 issues: $63.95; Dfl150. A New Journal. Liquid Chromatographic Data Compilation. Sponsored by ASTM Committee E-19 on Chromatography.Atomic and Molecular Data Series AMD 41. Pp. x + 186. Philadelphia: American Society for Testing and Materials. 1975. Price $15. Grundlagen und Methoden der chemischen Emissionsspektralanalyse. Eine Einfuh- rung mit praktischen Arbeitshinweisen. R. Mannkopff and G. Friede. Pp. x + 218. Weinheim/Bergstr. : Verlag Chemie, GmbH. 1975. Price DM78. Fortran IV in Chemistry. An Introduction to Computer-assisted Methods. G. Beech. Pp. x + 303. London, New York, Sydney and Toronto : John Wiley & Sons. 1975. Price f18.75. The ‘Practising Chemists’ A History of the Society for Analytical Chemistry 1874-1 974 By R. C. CHIRNSIDE and J. H. HAMENCE 225 pages; 11 plates CS Members f 2-50 ISBN 0 85990 700 9 f 3-00; u.s.S8.00 Obtainable from The Publications Sales Officer, The Chemical Society, Blackhorse Road, Letchworth, Herts. SG6 1 HN

ISSN:0306-1396    

DOI:10.1039/AD9751200325

出版商:RSC    

年代:1975

数据来源: RSC

摘要:

December, 1975 REPRINTS OF REVIEW PAPERS Reprints of Review Papers 327 Reprints of the following Review Papers published in The Analyst since 1964 are available from Publications Sales Officer, The Chemical Society, Blackhorse Road, Letchworth, Herts. , SG6 1 HN (not through Trade Agents). The price per reprint is 50p; orders for four or more reprints of the same or different Reviews are subject to a discount of 25 per cent.The appropriate remittance, made out to The Chemical Society, should accompany any order. “Some Analytical Problems Involved in Determining the Structure of Proteins and Peptides, ” “The Faraday Effect, Magnetic Rotatory Dispersion and Magnetic Circular Dichroism, ” by “Electrophoresis in Stabilizing Media,” by D. Gross (July, 1965). “Recent Developments in the Measurement of Nucleic Acids in Biological Materials,” by “Radioisotope X-ray Spectrometry,” by J.R. Rhodes (November, 1966). “The Determination of Iron(I1) Oxide in Silicate and Refractory Materials,” by H. N. S. “Activation Analysis,” by R. F. Coleman and T. B. Pierce (January, 1967). “Techniques in Gas Chromatography. Part I. Choice of Solid Supports,” by F.J . Palframan “Heterocyclic Azo Dyestuffs in Analytical Chemistry,” by R. G. Anderson and G. Nickless “Determination of Residues of Organophosphorus Pesticides in Food,” by D. C. Abbott and “Radioactive Tracer Methods in Inorganic Trace Analysis : Recent Advances,” by J . W. “Gamma-activation Analysis,” by C. A. Baker (October, 1967). “Precipitation from Homogeneous Solution,” by P.F. S. Cartwright, E. J. Newman and “Industrial Gas Analysis,” by (the late) H. N. Wilson and G. M. S. Duff (December, 1967). “The Application of Atomic-absorption Spectrophotometry to the Analysis of Iron and “Inorganic Ion Exchange in Organic and Aqueous - Organic Solvents,” by G. J . Moody and “Radiometric Methods for the Determination of Fluorine,” by J . K. Foreman (June, 1969).“Techniques in Gas Chromatography. Part 11. Developments in the van Deemter Rate Theory of Column Performance,” by E. A. Walker and J . F. Palframan (August, 1969). “Techniques in Gas Chromatography. Part 111. Choice of Detectors,” by T. A. Gough and E. A. Walker (January, 1970). “Laser Raman Spectroscopy,” by P. J . Hendra and C. J. Vear (April, 1970). “Ion-selective Membrane Electrodes,” by Ern0 Pungor and Kliira T6th (July, 1970).“X-ray Fluorescence Analysis,” by K. G. Carr-Brion and K. W. Payne (December, 1970). “Mass Spectrometry for the Analysis of Organic Compounds,” by A. E. Williams and H. E. “The Application of Non-flame Atom Cells in Atomic-absorption and Atomic-fluorescence “Liquid Scintillation Counting as an Analytical Tool,” by J .A. B. Gibson and A. E. Lally “The Determination of Some 1 ,kBenzodiazepines and Their Metabolites in Body Fluids,’ ’ “AtorLic-fluorescence Spectrometry as an Analytical Technique, ’’ by R. F. Browner (October, 1974). “The Use of Precipitate Based Silicone Rubber Ion-selective Electrodes and Silicone Rubber Based Graphite Voltammetric Electrodes in Continuous Analysis, ” by 2s. Fbher, G.Nagy, K. T6th and E. Pungor (November, 1974). “The Examination of Meat Products with Special Reference to the Assessment of the Meat Content,” by D. Pearson (February, 1975). “Chemiluminescence in Gas Analysis and Flame-emission Spectrophotometry, ” by J . H. Glover (July, 1975). “The Analytical Role of Ion-selective and Gas-sensing Electrodes in Enzymology,” by G. J. Moody and J. D. R. Thomas (September, 1975). by Derek G. Smyth and D. F. Elliott (February, 1964). J . G. Dawber (December, 1964). H. N. Munro and A. Fleck (February, 1966). Schafer (December, 1966). and E. A. Walker (February, 1967). (April, 1967). H. Egan (August, 1967). McMillan (September, 1967). D. W. Wilson (November, 1967). Steel,” by P. H. Scholes (April, 1968). J. D. R. Thomas (September, 1968). Stagg (January, 1971). Spectroscopy,” by G. F. Kirkbright (September, 1971). (October, 1971). by J. M. Clifford and W. Franklin Smyth (May, 1974).

ISSN:0306-1396    

DOI:10.1039/AD9751200327

出版商:RSC    

年代:1975

数据来源: RSC