摘要:

Proceedinas - cof the Analytical Division 0.FThe Chemical Society237240240264266267269270270271274C'UNTENTSProposed LegislationSummaries of Papers'Research and DevelopmentTopics in AnalyticalChemistry'Equipment NewsCorrespondenceThe Analytical ChemistryTrustReport on the Second JointACS/CIC ConferenceNew PharmacopoeiaCommission ChairmanMeetings and CoursesPublications ReceivedAnalytical Division DiaryVolume 14 No 9 Pages 237-274 September 197PADSDZ 14(9)237-274(1977)ISSN 0306-1396September 1977PROCEEDINGSANALYTICAL DIVISION OF THE CHEMICAL SOCIETYOF THEOfficers of the Analytical Divisionof The Chemical SocietyPresidentD. W. WilsonHon. SecretaryP. G. W. CobbSecretaryMiss P. E. HutchinsonHon. Treasurer Hon.Assistant SecretariesJ. K. Foreman D. I. Coomber, O.B.E.; D. C. M. Squirrel1Editor, 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, Distribution Centre, Blackhorse Road,Letchworth, Herts., SG6 1HN.Non-members can only be supplied with Proceedings as part of a combined subscription with The Analysrand Analytical Abstracts.(9 The Chemical Society 1977ANALYTICAL SCIENCES MONOGRAPH No. 3Pyrolysis-Gas Chromatographyby R. W. May, E. F. Pearson and D. ScothernChapter 1 serves as an introduction to gas chromatography andwill be of interest to those unfamiliar with the technique.Theseveral methods of pyrolysis used in pyrolysis-gas chromato-graphy are described in Chapter 2; their merits and demerits inparticular applications are discussed. The major analytical uses ofthe technique are presented in Chapter 3; the general analytical'fingerprinting' aspects are described separately from the methodas applied to specific sample typek. Chapter 4 deals with theidentification of the pyrolysis products which are eluted from thechromatography column, useful extra information allowing thepossibility of naming a pyrolysed sample without recourse to aknown identical sample. The necessity for increased standardiza-tion of the technique of pyrolysis-gas chromatography isdiscussed in Chapter 5.Clothbound 117pp 8%'' x 6" 0 85186 767 7 f7.20 ($14.40)CS Members f5.50THE CHEMICAL SOCIETYDistribution Centre, Blackhorse Road, Letchworth,Herts. SG6 1 HN Englan

ISSN:0306-1396    

DOI:10.1039/AD97714FX027

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

272 PUBLICATIONS RECEIVED Proc. APzaZyt. Div. Chenz. SOC.Analytical Division Diary, continuedOctober, continuedFriday, 14th, 5 p.m. : ExeterWestevn Region, jointly with the PeninsulaSection of the CS.“Polarography in Environmental and MarineChemistry,” by Professor H. W. Niirnberg.Department of Chemistry, The University,Exeter.Monday, 17th, 4.30 p.m. : EdinburghScottish Region, jointly with the Edinburghand East of Scotland Section of the CS andthe Heriot-Watt University ChemicalSociety.“Studies of Toxic Trace Metals in theEnvironment by Advanced PolarographicMethods,” by Professor H. W. Nurnberg.Mountbatten Conference Theatre, Heriot-Watt University, Grassmarket, EdinburghSeptember, 1977 ANALYTICAL DIVISION DIARY 273Analytical Division Diary, continuedSeptember, continued“Studies of Dental-enamel Surfaces by FlowPlymouth Polytechnic, Plymouth, Devon.Microcalorimetry,” by M. V.Stack.Tuesday to Thursday, 20th to 22nd:AberdeenCS Autumn Meeting : Analytical DivisionSymposium on “Soils, Geochemistry andthe Exploitation of Mineral Resources.”Tuesday, 20th-“Analytical Aspects of Soil Trace ElementStudies,” by R. L. Mitchell.“Techniques in the Analysis of Soil forAgricultural Purposes,” by R. J. Hall.“Spectrochemical Techniques in Soil Analy-sis,’’ by R. 0. Scott and Dr. M. L. Berrow.“Chemical Characterisation of Mineral Com-ponents in Soil,” by B. D. Mitchell andB. F. L. Smith.“Lead Levels in Soils from Urban and RuralAreas of Birmingham,” by A. K. Khera andProfessor D.G. Wibberley.“Natural Isotopic Abundances in Soil OrganicMatter,” by D. D. Harkness.“The Application of the Inductively CoupledPlasma (ICP) as an Excitation Source inApplied Geochemical Analysis,” by M.Thompson.“Studies of Metal Complexes on Clay Min-erals,” by Parissa Monsef-Mirzai, J. W.Gaskarth and W. R. McWhinnie.Wednesday, 2 1st (a .m .)-“Analysis in Mineral Exploitation,” byP. J. Moore.“Carrock Fell : The Development and Oper-ation of a Small United Kingdom TungstenMine,” by P. Knowles.“Rare Earths : Their Determination andSignificance in Geochemical Studies,” byP. Bowden and J . E. Whitley.The University, Aberdeen.OCTOBERTuesday, 4th, 10.30 a.m.: LondonBiological Methods Group on “Short TermTesting of Chemicals for Mutagenicity andCarcinogenicity.I ’Topics for discussion-“Principles and Significance of Short Term“Test Procedures Available.”“Methodology and Predictive Value.”“Legal Implications with Particular Refer-ence to the Health and Safety a t WorkAct.”The Zoological Society of London, RegentsPark, London, NW 1 4RY.Tests. ’’Tuesday, llth, 2 p.m.: Stoke-on-TrentEducation and Training GroupDiscussion on “Methods of Assessment ofPostgraduate, Undergraduate and Prac-tical Work,” introduced by B. Mills andH. Bennett.North Staffordshire Polytechnic, Stoke-on-Trent.Wednesday, 12th, 6.30 p.m. : LondonMicrochemical Methods Group.Discussion on “Silicate Rocks-Analysis andThe Savoy Tavern, Savoy Street, W.C.2.South East Region and Atomic SpectroscopyGroup.Discussion on “Instrumental Analysis-Is i tCost Effective?” introduced by K.M. Billsand C. Woodward.Southside Senior Common Room, PrincesGardens, Imperial College, London, S.W.7.Analytical Division on “Topics in Environ-mental and Marine Chemistry.”“Studies on Toxic Trace Metals in theEnvironment by Advanced Pola.rographicMethods.” by Professor H. W. Nurnberg.“Trace Mercury and Methylmercury Com-pounds in Fish,” by H. Egan.“Some Applications of X-ray Microanalysis toBiological Problems,” by P. F. Newell.Geological Society of London Lecture Thea-tre, Burlington House, Piccadilly, London,W.l.Standards,” introduced by E. C. Hunt.Wednesday, 12th, 7 p.m. : LondonThursday, 13th, 2.30 p.m.: LondonThursday, 13th, 4 p.m.: BelfastNorthern Ireland Sub-committee, jointly“New Analytical Techniques Based onChemistry Department, The Queen’s Univer-with the Andrews Club.Hydrogen Flames,” by A. Townshend.sity, Belfast.Friday, 14th, 7 p.m. : HarrogateNorth East Region : Social evening.Dinner, followed by “Magic and MysteryThrough the Ages,” by Professor and Mrs.E. A. Dawes.Granby Hall Hotel, Harrogate.North West Region, jointly with the SouthCheshire Branch of the PharmaceuticalSociety.“Analytical Problems in Drug Toxicology,”by B. Scales.ICI Pharmaceuticals Division, Tenant’s HallConference Centre via Bollington Lodge,Alderly Park, Macclesfield, Cheshire.[continued on p. 272Friday, 14th, 6.30 p.m. : MacclesfielAnalytical Division DiarySEPTEMBERTuesday to Thursday, 13th to 15th: LondonElectroanalytical Group, jointly ‘with the Elec-trochemistry Group of the Faraday Divi-sion : Anglo - Czech Symposium on Polaro-Tuesday 13th and Wednesday 14th : Papers onThzcrsday 15th, 9.30 a.m.: “Electroanalysis.”“Development of Electrochemical Instru-mentation Derived from Polarography,” byR. Kalvoda.“Recent Developments in Ion-selectiveElectrodes/Potentiometry,” by J. D. R.Thomas.“Measurement of Potassium Levels in BloodUsing Ion-selective Electrodes,” by D. M.Band and T. Treasure.“The Uses of Electrochemical Techniques inBiology and Clinical Analysis,” by Dr. A1Serak.“Continuous Blood Gas Analysis in the Clini-cal Environment,” by D.Parker.“Enzyme Electrodes-A Survey,” by B.Fleet.“New Directions in Instrumentation forPolarography,” by G. C. Barker.Imperial College, South Kensington, London,s.w.7.P P h Y *electrochemistry.Tuesday to Friday, 13th to 16th: BathRadiochemicd Methods Group : ScintillationThe Assembly Rooms, Bath.Counting Symposium.Monday to Wednesday, 19th to 21st: Ply-mouthThermal Methods Group, jointly with Associa-tion Franqaise de Calorimetrie et d’ AnalyseThermique : Symposium on Thermal Analy-sis and Calorimetry.“Caract6ristiques Thermiques du VerreCd,GeAs, e t Cin6tique de Cristallisation,” byB. Auguin, A. Defresne, Nguyen Van Dongand Tran Huu Danh.“Some Aspects of Simultaneous ThermalAnalysis - Mass Spectroscopy,” by P.A.Barnes.“Thermogravimetric Studies on the Oxidationof Zinc Sulphide,” by B. Basak, D. R.Glasson and S. A. A. Jayaweera.“Review of Thermal Instrumentation Deve-loped at NHLBI and Applications toEnzyme Kinetics and Thermodynamics,”by R. L. Berger.“Thermogravimetric Studies of the Formationand Oxidation of Silicon Nitride,” by B. J.Brockington, D. R. Glasson and J. A.Jones.“Study of Exothermic Reactions by Quantit-ative DTA,” by E. L. Charsley.“Thermogravimetric Studies of the Oxidationof Boron Carbide,” by A. A. Chaudhry,D. R. Glasson and J. A. Jones.“Thermosonimetry,” by G. M. Clark.“Thermal Analysis of Textile Fibres, ’’ by J. S.Crighton.“Enthalpies of Formation of Co - Cr Alloysby Sn-solution Calorimetry,” by D. B.Downie.“Thermogravimetric Test Procedures forPolymer and Elastomer Formulations,” by0.Dugdale.“Rapid Characterisation of Coal by Thermo-gravimetric and Scanning Calorimetricanalysis,” by R. L. Fyons.“Thermogravimetric Studies of Milled Hydr-ated and Carbonated Limes,” by R. B.Gammage, D. R. Glasson and R. Srodzinski.“Weight Change Studies of the Formationof Polybenzoxazole,” by F. Ghaffari andK. A. Hodd.“Thermogravimetric Studies of Natural andSynthetic Calcium and Magnesium Phos-phates,” by D. R. Glasson and Diane E.B. Linstead-Smith.“Modes of Thermal Decomposition ofAmmonium and Alkylammonium IonicForms of Crystalline Insoluble Acid SaltsofTetravalent Metals,” by J . P. Gupta andD. V. Nowell.“Heat of Formation of the Ordered Co - GaPhase,” by E.-Th. Henig and H. C. Lukas.“TG and DTA Studies on the Decompositionof Lead Sulphite,” by S. A. A. Jayaweeraand P. J . Sleeman.“Materials Testing by ThermomechanicalAnalysis and Dynamic MechanicalAnalysis,” by M. G. Lofthouse.“Hot-stage Microscopy of Alkaline-earthMetal Sulphites,” by P. O’Neill.“Effect of Processing Variables on the GlassTemperature of Polymers,” by M. J .Richardson.[continued inside back coverPrinted by Heffers Printers Ltd Cambridge Englan

ISSN:0306-1396    

DOI:10.1039/AD97714BX029

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

Vol. 14 No. 9 September 1977 Proceedings of the Analytical Division of the Chemical Society Proposed Legislation Part I : Introduction, UK Reviews of Current Legislation and EEC Sampling for Foodstuffs Introduction This article will outline the legislation currently under active discussion within the foodstuffs area, with particular emphasis being placed on analytical methodology. Part I will describe mainly non-EEC generated legislation and the second part EEC generated legislation.Micro- biological aspects of foodstuff s legislation will not be discussed in this article. Foodstuffs legislation in the UK results from either internal (national) considerations or from activities of the EEC. The procedure for draw- ing up both UK and EEC generated legislation has been described by Sawyer.l It will be seen from his article that the vital difference to the food analyst between the UK and the EEC approaches to foodstuffs legislation is that the former does not, in general, recommend that statutory methods of analysis or sampling be included in Regulations whereas it is the intention of the latter, EEC, approach to lay down in detail the methods of analysis and sampling required to verify the standards pre- scribed in foodstuffs Directives. Therefore as UK legislation becomes more EEC orientated the analyst’s prerogative to select a method to enforce a particular standard will become restricted as he will have to use a statutory procedure, when considering ‘‘official” samples, to enforce EEC generated legislation.An important difference between the manner in which the EEC legislation is drawn up for food- stuffs standards (whether compositional, addi- tive or contaminant) on the one hand and the methods or sampling required to enforce such standards on the other is that the former is required to pass through the full Council pro- cedure (at which every Member State has the power of veto) whereas the latter is required to pass through the Standing Committee for Food- stuffs procedure (where a qualified majority voting is sufficient to ensure ratification of a method of analysis or sampling Directive).As the qualified majority voting procedure is used for analytical methods/sampling Direc- tives it is essential that there is the widest con- sultation within the UK on the proposed analytical methods a t the earliest stage possible in the development of a method of analysis Directive. It is to aid such consultation that the Ministry of Agriculture, Fisheries and Food (MAFF) set up the Consultative Committee on EEC Methods of Analysis in October 1974.Representatives from industrial organisations, research associations, learned societies, the British Standards Institution, the Laboratory of the Government Chemist and the Association of Public Analysts were invited to the Commit- tee.In addition, to facilitate discussion a t the detailed technical level, the Committee recently agreed to set up a series of small Working Groups to discuss methods for specific topics. The membership of these Working Groups is drawn from foodstuffs analysts with practical experience of the topic under consideration and who are able to be nominated as representing a particular interest.The membership of each Working Group will always include nominated representatives of the Association of Public Analysts, the Laboratory of the Government Chemist and appropriate trade organisations. The Working Groups aim to produce a con- sidered opinion on the analytical methodology under discussion, which is supported by the representatives of the three different view- points in the UK : manufacturer, enforcement analyst and referee analyst. The Consultative Committee membership is regularly and promptly informed of all analyti- cal methods circulated by the EEC Commission.Other food analysts are notified of such methods 237238 Subject Antioxidants Arsenic Artificial sweeteners Asbestos Beer Colours Flavourings in food Infant foods PROPOSED LEGISLATION TABLE I Proc.Analyt. Div. Chem. Soc. FOODSTUFFS LEGISLATION UNDER REVIEW IN THE UK Committee FACC FACC FACC FACC FSC/FACC FACC FACC FSC/FACC Labelling of food FSC Lead FACC Meat products FSC Mineral hydrocarbons FACC Miscellaneous classes FACC of food additives Modified starches FACC Novel protein foods FSC Present position The Committee’s Report on Antioxidants in Food was published in January 1975.After considering representations on the Keport, proposals for new Regulations were issued on March 21, 1977. The Committee was asked to review the Arsenic in Food Regula- tions 1959, and its Report is in preparation. The Committee is considering an application t o allow Aspartame t o be added t o the list of permitted artificial sweeteners in the UK.Its recommendation is awaited. The Committee was asked, in April 1976, to examine the question of asbestos in food. Representations were invited and the Committee’s Report is awaited. The FSC Report on Beer was published in March 1977. Kepre- sentations on the Report have been requested and will be con- sidered.The FACC is a t present considering additives and processing aids used in the production of beer. The Committee was asked, in August 1974, t o review the Colouring Matter in Food Regulations 1973; comments were invited and the Report of the Committee is awaited. The Report on the Review of Flavourings in Food was published in March 1976.Representations have been invited on the Report and are being considered. The FSC was asked, in April 1974, to advise on infant foods. Comments were requested and the Committee’s Report is awaited. The FACC was requested, in April 1973, t o review the use of additives in infant and baby foods. Comments were invited and the Report of the Committee is awaited.The Committee was asked to review the labelling and advertising of food in January 1975 and its Report is in preparation. The Committee’s Report on the Review of the Lead in Food Regulations was published in December 1975. Representations have been invited and are being considered. The Committee was asked, in February 1975, t o review the Regul- ations under the Food and Drugs Act that lay down compositional, labelling and advertising requirements for a wide range of meat products, and to take account of the recommendations contained in its Report on Offals in Meat Products (1972) and in its Report on Novel Protein Foods (1975). The Committee, in its Review, will also be giving particular attention to the basis for control of meat content for meat products; the declaration of meat content for meat products; definitions of terms, e.g., curing, meat content, ready meals, meat products; fat levels and the incorporation of connective tissue ; the use of polyphosphates and similar agents in meat, including poultry, and in meat products; description of meat substantially modified during processing ; analytical techniques and methods of verification of composition of meat products, especially in relation to the content of meat and of other protein- rich constituents and sampling provisions for enforcement purposes.The Committee’s Report is in preparation. The Committee’s Report on the Review of the Mineral Hydro- carbons in Food Regulations was published in 1975. The repre- sentations on the Report are being considered.The Committee announced, in April 1973, that i t would consider all remaining classes of additives with a view to bringing all food additives under control of Regulations. The Committee is considering the use of modified starches in foodstuffs and will be issuing a Report shortly. The Committee’s Report on Novel Protein Foods was published in February 1975 and representations on the Report have been invited.Such representations are being considered, especially in conjunction with the current FSC Meat Products Review.September, 1977 Subject Solvents Sorbic acid Water in food PROPOSED LEGISLATION TABLE I - continued 239 Committee Present position FACC The Committee was asked, in June 1975, to carry out a Review of the Regulations that govern the use of solvents in food, and its Report is in preparation.The Committee was asked, in October 1975, to review the use of sorbic acid in food. The Committee was asked, in January 1975, to consider and report on water as a separate ingredient of fresh and processed food and its Report is in preparation. FACC FSC Its Report is in preparation. via the excellent Special Circulars on EEC methods issued by the British Food Manufactur- ing Industries Research Association or, in the instance of the enforcement analyst, via the MAFF Information Bulletin for Public Analysts.UK Reviews of Current Legislation Topics chosen for review are referred by Ministers to either the Food Standards Com- mittee (FSC), which advises and recommends on the composition, labelling and advertising of foodstuffs, or the Food Additives and Con- taminants Committee (FACC) , which advises and recommends on the need for and safety-in- use of additives and on the maximum levels of contaminants that can be tolerated in foodstuffs.Topics which are being discussed by. these Committees, or for which draft Regulations arising out of one of these Committees’ reports are in the course of preparation, are shown in Table I.It will be noted that, because all these topics arise as a result of UK reviews of current legislation, the recommendations or Regulations that are issued will probably follow the normal practice in UK foodstuffs legislation and not recommend or stipulate any analytical methods or sampling procedures. EEC Sampling for Foodstuffs It is argued by the Commission that the incorporation of the agreed provisions of EEC food compositional, additive or contaminant Directives into the national legislation of the Member States does not produce complete harmonisation of food legislation unless the appropriate methods of analysis and sampling are agreed within the Community and.enacted into national legislation.In the absence of agreed methods of analysis and sampling the Commission states that a compositional standard within a foodstuffs Directive is capable of being interpreted in different ways in different Mem- ber States even though each has, apparently, the same numerical standard in national legislation. The Commission therefore intends that sampling procedures as well as methods of analysis will be laid down to verify the composi- tional specifications of foodstuffs that fall within the scope of ratified Directives.Such samp- ling procedures will be subject to ratification by the Standing Committee for Foodstuffs. An example of a sampling plan for foodstuffs, albeit inadequate and incomplete, adopted by the EEC prior to UK accession is that now enacted into The Preservatives in Food Regul- ations 1975 (the sampling of citrus fruit treated with biphenyl, 2-hydroxybiphenyl or sodium biphenyl-2-yl oxide) .2 The Commission argument for the need to stipulate sampling procedures is best illustrated by using a standard that has already been translated into Member States’ legislation ; for example, the common standard for a maximum of 1% sulphated ash content in the dry matter of glucose syrup.3 In the UK this would be interpreted as meaning, that every item as sold, offered for sale or exposed for sale either at retail or through the distribution chain, should con- form to this standard.However, in another Member State it may be interpreted that the average of, say, ten individual .samples (if analysed separately) should conform to the limit of lyo, but that some individual analyses may be permitted to exceed 1%. It is to eliminate differences of interpretation of this type between Member States, of the require- ments or intent of food compositional standards, that the issue of sampling will be discussed within the EEC. MAFF intends t o set up a Consultative Committee on Methods of Sampling (to mirror the Analysis Committee described previously) in order that constructive discussion on the sampling of foodstuffs may take place within the UK while EEC discussions are at an early 1. 2. 3. stage. References Sawyer, R., Proc. Analyt. Div. Chem, SOC., 1976, 13, 238. SI 1975 No. 1487. The Specified Sugar Products Regulations 1976. SI 1976 No. 509.

ISSN:0306-1396    

DOI:10.1039/AD9771400237

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

240 RESEARCH AND DEVELOPMENT TOPICS Proc. AnaZyt. Div. Chem. Soc. Research and Development Topics in Analytical Chemistry The following are summaries of eleven of the papers presented at the Research and Develop- ment Topics in Analytical Chemistry meeting of the Analytical Division held on May 3rd and 4th, 1977, at Chelsea College, London and reported in the June issue of Proceedings (p. 131).Some Applications of Optoacoustic Spectroscopy to Solid Samples B. C. Beadle, M. J. Adams and G. F. Kirkbright Department of Chemistry, Imperial College, London, SW7 2A Y In optoacoustic spectroscopy (OAS), radiation from a continuum source is employed to illumi- nate small solid, semi-solid or liquid samples contained in a constant-volume cell in air.1-3 The energy absorbed by the sample subsequently appears as heat, which produces an increase in gas pressure in the cell.If the incident radiation is modulated in the frequency range 20 Hz-20 kHz a sensitive microphone transducer can be employed to monitor the periodic fluctuations in the gas pressure, which occur at the same frequency as that of the modulation. The absorption spectra of the samples can then be obtained by monitoring the magnitude of the signal produced at the microphone transducer at different wavelengths selected from the continuum source.A double-beam optoacoustic spectrometer has been developed in our laborat~ry,~ which allows automatic correction of the spectra obtained for the variation in output energy of the source with wavelength. The continuous radiation from a 300-W xenon arc source (Type VIX 300 UV, Varian Associates) is focused through a variable-speed rotating sector (Model 9479, Brookdeal Electronics Ltd., Brockwell, Berkshire) at the entrance slit of an f/4 plane- grating monochromator (Metrospec, V.A. Howe Ltd., London) and beam-split, after disper- sion, to pass to two identical exit slits. The radiation from each slit is then re-focused and directed into the optoacoustic cells employed.One of these cells contains the sample of interest and the other a carbon black reference absorber. The optoacoustic signals from the microphone transducers are taken to two lock-in amplifiers (Model 124A, Princeton Applied Research Corp., New Jersey, USA ; Model 9502, Brookdeal Electronics Ltd.), and the output from each amplifier is led to a ratiometer unit (Model 5057, Brookdeal Electronics Ltd.).The output of the ratiometer with wavelength corresponds to the optoacoustic spectrum for the sample, which has been corrected for variation in source power with wavelength. The spectra in the ultraviolet - visible region are obtained with a plane diffraction grating blazed at 300 nm (50 x 50 mm, 1 200 lines mm-l).In the near-infrared region, a similar grating blazed at 2 pm (295 lines mm-l) is employed with Chance 0 x 5 filters at each of the exit slits to prevent transmission of radiation at wavelengths less than 0.9 pm from overlapping spectral orders of diffraction. The ability of the spectrometer to produce a flat response with respect to wavelength for identical sample cells has been determined4 by mounting carbon black samples in both cells and examining the ratio of the output from each obtained as described above.The results obtained were considered satisfactory for double-beam spectrometric examination of samples. Applications The double-beam optoacoustic spectrometer can be employed over a wide range of wave- lengths with the continuum source to examine the optoacoustic spectra of both small liquid and solid samples.It has been applied to the examination of anumber of samples of geochemical, inorganic and biochemical interest in the 0.3-2.5-pm region of the spectrum. The spectra of several rare earth oxides have been obtained in the ultraviolet - visible and near-infrared regions, using approximately 100 mg of sample.The relatively sharp band absorption spectra of these compounds are characteristic of lanthanide( 11) compounds and provide good test samples with which to evaluate the spectral resolution and signal to noise ratios obtainable with the optoacoustic spectrometer and small solid samples.Sep t e m bey, I 9 7 7 RESEARCH AND DEVELOPMENT TOPICS 241 Thus it can be used to study biological systems, such as haemoglobin in whole blood, without the need to separate the compound of interest.The use of OAS rather than conventional techniques of absorption reflectance spectroscopy overcomes the problems associated with highly opaque samples or samples that scatter radiation strongly. The optoacoustic spectra of several compounds of pharmaceutical interest have been examin- ed in the near-infrared region (Fig.1). For samples of aspirin and paracetamol it was found that similar spectra are obtained from either a whole tablet or a powdered sample. The only difference between them is absorption bands that occur at about 1.4 and 1.9 pm, which are observed in the whole-tablet samples. These bands are characteristic of free, undissociated water and indicate surface absorption of atmospheric water by the tablet.The spectra of aspirin and paracetamol compared with commercial preparations containing these materials show clear similarities. However, almost all of the absorption bands in this spectral region involve hydrogen stretching vibrations, either overtones or combination bands. Hence the applications of qualitative techniques in this region are limited.Quantitative applications are possible when the analyte has clearly identifiable spectral bands. In the examination of a series of sulphonamides, absorption bands in the 1.6-pm region are observed that are character- istic of -NH stretching vibrations. The double-beam optoacoustic spectrometer has also been employed for solution transmis- sion studies.The solution of interest is placed before the sample optoacoustic cell, containing a carbon black sample, in a silica cuvette. The cell serves as a detector of the transmitted radiation. This technique of examining transmission data is useful for wavelength calibration purposes, and has been employed for this purpose in the near-infrared region. OAS can also be employed via phase analysis of the resultant signal to provide information concerning the spectra, thermal diffusivity or thickness of samples composed of distinct layers.5 The application of the optoacoustic effect to the direct determination of absolute fluorescence quantum efficiencies has also been studied in our laboratory.6 OAS can be used to examine directly both solid and liquid samples.1 I I 1.5 2.0 2.5 Wavelength/pm Fig. 1. (a) Optoacoustic spectrum of paracet- amol between 1 and 2.6 pm; and (b) optoacoustic spectrum between 1 and 2.6pm of a commercial preparation containing paracetamol (70.2%) and codeine phosphate (sorbitol) (1.1 yo).242 RESEARCH AND DEVELOPMENT TOPICS Proc. Analyt. Div. Chem. SOC References 1 . Adams, M. J., King, A.A., and Kirkbright, G. F., Analyst, 1976, 101, 7 3 . 2 . Rosencwaig, A., Analyt. Chem., 1975, 47, 592A. 3. Adams, M. J., Beadle, B. C., King, A. A., and Kirkbright, G. F., Analyst, 1976, 101, 553. 4 . Adams, M. J . , Beadle, B. C., and Kirkbright, G. F., AnaZyst, 1977, 102, 569. 5 . Adams, M. J., and Kirkbright, G. F., Analyst, 1977, 102, 281. 6 . Adams, M. J., Highfield, J.G., and Kirkbright, G. F., Analyt. Chem., in the press. H ig h-performance Liquid Chromatography of Bleomycins C. R. Williams Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, LE11 3TU The bleomycins are a group of water-soluble, basic glycopeptide antibiotics produced by Streptomyces verticillus (ATCC 15003). The bleomycins have a common structure (Fig.1) but differ in the terminal amine side-chain (Table I). Fig. 1 . Structure of bleomycins. Bleomycins extracted from the culture filtrate are obtained% a copper-chelate form. Both the copper-chelated and copper-free bleomycins are active but the latter form isless toxic and the copper-free bleomycin mixture is used clinically.1 Commercial bleomycin consists of two major components, A, and B,, and several minor components; the A, and B, forms constitute approximately 90% of the mixture.Bleomycin has been found to be effective TABLE I STRUCTURES OF TERMINAL AMINE GROUPS IN BLEOMYCINS Bleomycin Terminal amine group A, -NH-(CH,),-S-CH, II I CH3 0 -NH-(CH,),-S+-CH, A2 Demethyl- A, -NH-( CHZ),-S-CH, BZ -NH- (CHz)a-NH-C-NH, It NHSeptember, 1977 RESEARCH AND DEVELOPMENT TOPICS 243 against squamous cell carcinoma and is used in the treatment of this type of cancer.2 By taking advantage of the ability of the bleomycins to form strong complexes with di- or trivalent transition metal ions, e.g., 5'Co(II) and ll1In(III), radioactively labelledcompounds 394 can be produced and concentrated within a tumour, thus enabling the tumour to be located by scanning procedures.The several procedures used to separate bleomycins are lengthy and time consuming,l and it was therefore decided to devise a rapid high-performance liquid chromatographic (HPLC) separation. The HPLC separations were carried out on a Waters, Model 6000, high-performance liquid chromatograph in conjunction with a Type 660 solvent programmer.The columns used were made of stainless steel, with dimensions 300 x 4 mm i.d. An ultraviolet detector operating at 254 nm was employed. Table I1 lists the column systems and conditions used. TABLE I1 COLUMN CONDITIONS Column system Mobile phase Operating conditions pPorasil . . . . . . 0.3% ammonium formate - Room temperature ; flow-rate pBondapak-C,, . . . . 80% aqueous methanol Room temperature; flow-rate methanol (1 + 1) containing 5 m M ammonium formate 2.0 cm3 min-1; pressure 3 000 p.s.i.0.5 cm3 min-l; pressure 1 000 p.s.i. The identities of the separated components were confirmed by (i), comparison with retention times of standard bleomycins; and (ii), thin-layer chromatography on silica gel using 10% ammonium acetate - methanol (1 + 1).The R, values were compared with those of the bleomycin complex. The bleomycin samples subjected to HPLC on pPorasil gave rise to three peaks: the two major components (A, and B,) and a minor component (A,) (Table 111). TABLE I11 RETENTION TIMES AND R, VALUES OF THE FREEZE-DRIED COMPONENTS AFTER ~PORASIL CHROMATOGRAPHY RF value Retention time/min Bleomycin Literature Obtained 4 11.5 3 0.68 0.40 0.74 0.68 0.40 0.72 0.72 Previous workers had shown that bleomycin A, was converted into bleomycin DMA, and A, on freeze drying and ~xidation,~ which could explain the two spots obtained with the most strongly retained component.The mobile phase was a methanol - water mixture to which a small amount of counter ion was added, e.g., perchlorate or formate. The counter ion suppresses the ionisation of bleomycin A, and B, by forming ion-pair complexes with these components. These ion-pair complexes are retained to some extent on the lipophilic stationary phase.When 2 mM perchlorate was used as a counter ion, a single fast-moving peak was obtained for bleomycin A, and B,. When 5 miu ammonium formate was used, two fast-moving peaks with retention times of 7 and 10 min were obtained. The faster peak was identified as bleomycin B, and the slower peak as bleomycin A,.Work is proceeding on a method for the determination of bleomycins in biological fluids using HPLC and electrophoretic procedures. The second column system used was reversed-phase HPLC using PBondapak-C,,. References 1. Umezawa, H., Pure Appl. Chem., 1971, 28, 665.2. Ichikawa, I., J . Jap. Med. Ass., 1969, 61, 487.244 RESEARCH AND DEVELOPMENT TOPICS Proc. AnaZyt. Div. Chem. SOC. 3. Nouel, R., Renault, W., Robert, J., Jeanne, C., and Wicart, L., Nouv. Presse Med.. 1972, 1, 95. 4 . Thakur, M. L., Merrick, M. V., and Gunasekera, S. W., “New Developments in Radiopharmaceuticals 5. Eckelman, W. C., Rzeszotarski, W. J., Siegel, B. A., Kubota, H., Chelliah, M., Stevenson, J., and Reba, and Labelled Compounds,” Volume 2 , IAEA, Vienna, 1973, p.183. R. C., J . Nucl. Med., 1975, 16, 1033. Extraction and Separation of Metal Ions by Foam-supported Reagents M. P. Maloney, G. J. Moody and J. D. R. Thomas Chemistry Department, University of Wales Institute of Science and Technology, Cardifl, CF1 3N U Various papers deal with the use of polyurethane foam as a support for extraction agents such as tribut yl phosphate, t ri-n-oc t ylamine, di t hizone3 9 and 1 -nit roso-2-napht hol.5 In part icu- lar, the chelating agents are of use in the pre-concentration of metals from natural waters. Attention is also focused on the pre-concentration of organic pesticides in pollution studies.6~7 The present study deals with the performance of the liquid anion exchanger Amberlite LA2 when coated on to a polyether-type polyurethane foam.The behaviour of the foam alone towards thiocyanate - metal complexes is also described. Coated-foam Anion Exchanger An anion-exchange foam with an equal mass of Amberlite LA2 can be prepared by stirring polyurethane foam with about twice its mass of the liquid ion exchanger and removing the excess of exchanger by pressing the coated foam between sheets of filter-paper.It is convenient to take 0.1 g of coated foam or solid anion-exchange resin in 20 cm3 of solution for batch kinetic and equilibrium studies. The results for the uptake of cadmium are presented in Table I. TABLE I RATE OF EXTRACTION OF CADMIUM (INITIALLY 0.5 mM) FROM 2 M HYDROCHLORIC ACID BY VARIOUS SOLID STRONG-BASE RESINS AND BY FOAM COATED WITH AMBERLITE LA2 (48% m/m) Time/min 1 5 10 20 40 60 120 180 SKA7 1 * 70.0 83.0 86.0 87.0 88.0 88.0 88.0 88.0 SR56At 78.0 85.0 85.0 86.0 86.0 - - 85.0 Extraction of cadmium, yo A SR65$ SRAKS Amberlystl I 29.0 19.0 16.0 52.0 39.0 37.0 61.0 49.0 51.0 68.0 64.0 60.0 74.0 66.0 71.0 77.0 76.0 - 81.0 81.0 - 83.0 84.0 81.0 - Coated foam 46.0 61.0 70.0 80.0 86.0 88.0 - - * SRA71: 100-200 mesh, 7-9% cross-linking.f SR56A: 52-100 mesh, 3 4 % cross-linking. $ SR65: 14-52 mesh, 3 4 % cross-linking. 5 SRAK: 14-52 mesh, 7-9% cross-linking. 11 Amberlyst : 45-55 mesh, macroreticular. The rate of extraction of the cadmium chloride complex by the coated foam is intermediate between those for the fine mesh (52-100, 100-200) and coarse mesh (14-52) solid resins.The effect of the degree of cross-linking on the extraction is detectable but less significant than that of particle size. The equilibrium capacity of the foam and resins is approximately the same (Table I). For the behaviour of metal ions in various concentrations of hydrochloric acid the results shown in Table I1 are obtained. Nickel, copper, cobalt and lead are not extracted to a significant extent at any acidity.Apart from the anomalous behaviour of iron(II1) between 4 and 7 M acidity the results parallel those obtained for solid-resin exchangers and solvent-extraction systems employingSeptember, 1977 RESEARCH AND DEVELOPMENT TOPICS TABLE I1 245 PERCENTAGE EXTRACTION OF METAL IONS (ALL 0.5 mM INITIALLY) FROM HYDROCHLORIC ACID OF VARIOUS CONCENTRATIONS BY AMBERLITE LA2 SUPPORTED ON FOAM (48% m/m) Hydrochloric acid/M 0 0.3 0.7 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 Cd(II), % 0 64.7 71.0 75.0 78.0 72.0 65.4 56.5 35.5 18.5 7.0 1.6 0.0 Fe(III), % 17.6 2.4 8.5 17.1 58.1 80.5 86.5 85.8 83.9 85.2 93.8 97.0 98.1 Hg(II), % 64.4 96.4 99.1 97.5 94.5 92.1 89.0 83.8 73.1 56.9 43.5 30.9 - Sn(IV), % 95.1 53.5 67.6 77.2 83.3 87.8 86.9 84.3 83.4 78.7 72.6 67.4 - Zn(II), % 13.1 10.6 25.6 29.2 54.4 55.9 48.7 36.1 24.0 16.6 12.1 8.2 7.0 Amberlite LA2.The foam-supported liquid anion exchanger extracts as efficiently as a 10% solution of the anion exchanger in 9-xylene. A column of the anion-exchange foam can be prepared by using the vacuum-packing technique of Braun and Farag.8 Quantitative separations can be achieved : for example, 100 pg of iron(II1) - copper(I1) and cadmium - zinc were resolved on an 80 x 15 mm column containing 3.0 g of the foam at a flow-rate of 1 cm3 min-l.Extraction by Polyurethane Foam Plugs Bowens first reported the ability of polyether-type polyurethane foam to extract metal complexes and noted its strong affinity for thiocyanate complexes. The present, more detailed, studies show that 0.5 mM concentrations of colbat(II), cad- mium(II), iron(II1) and zinc( 11) are extracted quantitatively from solutions of thiocyanate con- centration greater than 0.4 M.Hydrochloric acid of concentration up to 3 M has no effect on the ion extraction, but when increased to 5 M it causes a 50/, decrease in extraction.Such a lack of selectivity is useful when pre-concentration of several metals is desired. The rela- tively high concentration of the thiocyanate in the aqueous phase implies that the presence of interfering ions, such as sulphate or phosphate, should be less critical than in chelate systems where the extractant is present in the aqueous phase at very low concentrations.The capacity of the foam for the cobalt(I1) and iron(II1) complexes is 10 g kg-l and 22 g kg-1, respectively. At low concentrations (5 p.p.m.) the distribution coefficients are 10 000 and 1 000, respectively. The metals can be recovered by using 0.1 M nitric acid a t 90 "C. The recovery of cobalt, cadmium, iron(III), mercury and zinc is 99, 108, 110, 82 and l05%, respectively.For pre-concentration studies a column 20 mni in diameter and 50 mm high is packed with foam plugs (about 1.5 g) and 1 dm3 of solutions of 0.4 M potassium thiocyanate solution containing 100 pg of cobalt, cadmium, iron(III), lead and zinc passed through at a rate of 5 cm3 min-l. The recoveries of the metals by 50 cm3 of hot 0.1 M nitric acid are shown in Table 111, which also illustrates the recoveries obtained when chloride, phosphate and sulphate are present at the 100 p.p.m.level. TABLE I11 PERCENTAGE RECOVERY OF METALS WHEN PRE-CONCENTRATING FROM 1 dm3 OF SOLUTION Recovery, yo f A -l Solution Co Fe Cd Zn Pb 0.4 M KSCN . . . . 98 97 37 97 26 0.4 M KSCN plus 100 p.p.m. of Sod2-, C1- and PO,2- . . .. 94 111 45 107 0246 RESEARCH AND DEVELOPMENT TOPICS Proc.Analyt. Div. Chem. SOC. Conclusion Foam-supported Amberlite LA2 is easily prepared and can be rapidly packed into a column. Separations can be carried out as for conventional anion-exchange resins but for critical applications care must be taken at the column-packing stage in order to ensure a uniform bed. The use of polyether-type polyurethane foam for pre-concentrating metal ions from a thiocyanate medium has been demonstrated and except for lead (Table 111) interfering ions have little effect at the 100 p.p.m.level. The Science Research Council is thanked for a Research Studentship (to M.M.). References 1. Braun, T., Bakos, L., and Szabo, Zs., Analytica Chim. Acta, 1973, 66, 57. 2. Braun, T, and Huszar, E., Analytica Chim. Acta, 1973, 64, 77. 3.Braun, T., and Farag, A. B., Analytica Chim. Acta, 1974, 69, 85. 4. Chow, A., and Buksak, D., Can. J . Chem., 1976, 53, 1373. 5. Braun, T., and Farag, A. B., Analytica Chim. Acta, 1975, 76, 107. 6. Uthe, J. F., Reinke, J., and O'Broadovich, H., Envir. Lett., 1974, 6, 103. 7. Uthe, J. F., and Reinke, J., Envir. Lett., 1972, 3, 117. 8. Braun, T., and Farag, A. B., Analytica Chim.Acta, 1972, 62, 476. 9. Bowen, H. J. M., J . Chem. SOC. ( A ) , 1970, 1082. Two-dimensional Light-element Profiling with the Nuclear Microprobe J. Huddleston and T. B. Pierce Instrumentation and Applied Physics Division, A E R E , Harwell, Oxfordshire, OX1 1 ORA Methods for examining the spatial distribution of light elements in a single dimension, using the nuclear microprobe, are now well established and have been demonstrated for several types of determination.172 Work reported in this paper was intended to provide a means of producing an initial, semi-quantitative, two-dimensional image of elemental distribution, prior to a more detailed analysis using the line-scan approach.As in previous work, the presence of light elements is detected by counting prompt particles emitted by nuclear reaction as a result of charged-particle bombardment.The nuclear reaction and energy of the projectile are chosen to produce the optimum yield of prompt particles from the wanted component, while avoiding activating the matrix and interfering elements. The experimental assembly comprising the microprobe has been described in detail else- where and exploits the micro-beam line on the 3-MeV electrostatic generator at AERE, Harwell.In contrast to previous work, in which the position of the sample relative to the ion beam was altered mechanically, for this work the micro-beam was deflected electrostatically in a television-type raster pattern. Beam movement was achieved by two triangular wave- form generators operating at 50 and 500 Hz, and outputs were amplified to voltages of up to 1 kV at the deflector plates ; the beam of a conventional cathode-ray oscilloscope was moved in synchronisation with the ion beam.Particles reaching the detector gave rise to a voltage pulse, which was amplified and fed to a single-channel pulse-height analyser. The single- channel analyser was set to accept pulses characteristic of particular elements and the output controlled the brightness of the oscilloscope spot.The image corresponding to an elemental distribution was formed by integrating the signal for a pre-determined dose, either by using a storage oscilloscope or with a Polaroid camera. Analytical information can be derived from measurement of X-rays, y-rays or charged particles resulting from nuclear reaction processes.Particle measurement was usually chosen for light-element analysis so that radioactive samples could be examined if required. The two-dimensional scanning technique was initially applied to the examination of distribu- tions of carbon, as determination of carbon provided a major workload for the microprobe. Analysis was based on the reaction, 12C(d,@)l3C, induced by deuterons of 1.3 MeV.The emitted proton has an energy of 3.4 MeV when measured at an angle of 135" to the directionSeptember, 1977 RESEARCH AND DEVELOPMENT TOPICS 247 of the incident ion beam. An example typical of the results obtained for carbon is given in Fig. 1 and shows the distribution of carbon along a section taken from the edge of a carburised steel; the carbon concentration decreases rapidly from the sample edge.Quantitative meaurements carried out during a point by point line scan of the same specimen indicate that the carbon concentration is about 3% at the edge, decreasing to 0.0570 towards the interior of the section. The present photographic method of data presentation has a narrow grey scale and is unsuitable for quantitative interpretation of data.There is, however, good semi-quantitative agreement between two-dimensional scanning and the line-scan approach. The two-dimensional method reveals that the carbon gradient is reasonably constant at all points along the section, a fact that would be tedious and expensive to establish with a series of line scans. The carbon can be seen to be fairly evenly distributed, but external deposits are present on the outer wall of the tube.Further examination of the sample showed additional deposits of carbon and oxygen on the inner surface of the tube. Carbon has penetrated to a depth of about 500 pm into the sample. The distribution of carbon across the section of 0.8-mm tube is given in Fig. 2. Fig. 1. Distribution of car- Fig. 2 . Distribution of carbon across a 0.8-mm bon at the edge of a carburised steel. tube. Although carbon analyses have provided the major workload for the microprobe, methods have been developed for the determination of most light elements, including oxygen, nitrogen, fluorine, boron, lithium and beryllium. For some applications, simultaneous measurement of X-rays with the products of nuclear reaction permits the concentration of light elements to be correlated with those of heavier ones, for example chromium with carbon and nitrogen with titanium. The two-dimensional scanning technique has now been used to provide images of distribu- tions of most of the light elements in appropriate samples. The technique is still in its infancy and while it has already proved useful it is capable of substantial improvement. The quality of the photographs generated is not normally as good as expected from electron microprobes. Developments at present being considered include the digital acquisition of data in order to permit the simultaneous determination of several elements, and mathematical processing to separate interferences. A greater grey-level scale would also be desirable to improve the presentation further. References 1. 2. Pierce, T. B., Peck, P. F., McMillan, J. W., and Jones, I. G., Nucl. Instrum. Meth., 1974, 118, 115. Olivier, C., McMillan, J. W., and Pierce, T. B., Nucl. Instvum. Meth., 1975, 124, 289.

ISSN:0306-1396    

DOI:10.1039/AD9771400240

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

248 RESEARCH AND DEVELOPMENT TOPICS Proc. Analyt. Div. Chem. SOC. Some Applications of Gas - Liquid Chromatography in the Investigation of the Relationship between Physiological Stress and Physical Activity L. S. Bark, R. A. Graveling and H. Thomason Human Performance Laboratory, University of Salford, Salford, M5 4 WT The concept of stress in human biology is far less definite than the rigid definition applied by engineers and physicists.The human body is in a state of dynamic equilibrium, with environ- mental stimulation (stress) tending to alter the internal balance of the body, which in turn acts through a complex series of feedback loops to maintain this equilibrium, a process known as homeostasis. The changes which occur in the body in response to stress are extremely diverse, ranging from behavioural changes to alterations in the chemical balance at the intracellular level.Much research has been directed towards the study of the level of hormones, either in the blood or in urine. However, to date, most of this attention has been paid to the individual endocrine systems. Although not a recent idea, the need for a multi-hormonal approach to stress research has received increasing support in recent years, with the growing awareness of the interdependence of the endocrine systems of the body.Such an approach was adopted as part of a study to examine the possible alleviation by physical activity of the potentially harmful physiological effects of mental activity. The main hormones of concern within this framework are the adrenal steroids (primarily cortisol) and the two principal catecholamines, adrenaline and noradrenaline.These two groups are chemically dissimilar and potentially involve two or more analyses. In addition, our awareness of the interdependence of different hormone systems directs our attention to other compounds that may have some bearing on the investigation, for example, serotonin and dopamine. An additional essential requirement of the research was that the experimental methods used should be as unintrusive as possible.Consequently, our attention was drawn to the analysis of urine rather than blood samples, as many subjects suffer some stress when blood samples are taken. The metabolism of cortisol produces a number of metabolites and traditional analytical techniques usually select a particular functional group, for example, the 17-oxogenic steroids. This group analysis may mask changes in the metabolism of cortisol that analysis of the individual metabolites would reveal.One further problem is that without extensive pre- purification biological samples may contain other compounds that contribute to the reaction.The need for a multi-hormonal analysis of urine providing some indication of changes in metabolism has led to the development of a technique, using GLC, that permits the semi- quantitative analysis of several chemically dissimilar groups of compounds together with an appraisal of alterations in metabolism. The technique and its development are described here. The technique involves initial solvent extraction of urine samples, followed by the prepara- tion of more volatile silyl derivatives of the urinary metabolites extracted.Subsequent temperature-programmed chromatographic analysis of the silyl derivatives provides a urinary metabolic profile from each sample. For the solvent extraction the original technique published by Dalgleish and co-workers1 has been followed using three 25-ml portions of ethyl acetate and then three of diethyl ether.Two modifications to the original technique have been made in order to improve the extraction process. Solid sodium chloride has been used instead of a saturated solution and, because of the formation of gels on shaking, the mixture is centri- fuged after shaking and the organic phase aspirated.Because of the extreme water sensitivity of some of the silyl derivatives, the mixture of organic solvents must be thoroughly dried. Following experiments in the use of vacuum drying, which was found to produce the degrada- tion of some products, it was decided to carry out an initial drying with magnesium sulphate (which has a relatively large water capacity but leaves a high residual vapour pressure of water) and a final drying with calcium sulphate.The analysis requires the evaporation of the organic mixture, the residue being taken up in dry methanol and evaporated to dryness. The original technique used hexamethyldisilazane as a silylating agent, with trimethyl- chlorosilane as a catalyst. In the present technique bis(trimethylsily1)trifluoroacetamide isSpetember, 1977 RESEARCH AND DEVELOPMENT TOPICS 249 used, again with trimethylchlorosilane.The second system does not produce a precipitate of ammonium chloride and is a better silylating agent for sterically hindered steroids. Following early work with packed columns, using DC-560 as a stationary phase, a change was made to the more thermally stable OV-silicones, initially in packed columns, but sub- sequently open capillary columns coated with OV-101 were used, providing a greater power of resolution in a relatively short time.The limiting factor with the present equipment is the PTFE tubing linking the all-glass injection system to the column, as this begins to sublime at 285 "C. Compound peaks were quantified in terms of peak height, which was measured as part of the automatic data analysis described below.In order to examine the variability of individual peaks under differing experimental treatments, results were expressed in terms of the ratio to an internal standard (hexacosane). As the main interest in the research is this comparison of changes in individual peaks, it is not necessary to use response factors, as these would be constant for a given compound.Peaks have been identified on the basis of published methy- lene units combined with retention times of the unknown peaks and those of pure samples. Peaks have not been identified on the basis of methylene units alone, because of the uncer- tainty expressed by a number of authors on the reliability of this measure. However, in conjunction with physiological knowledge of compounds occurring in urine they have been useful in directing attention to the areas of the chromatogram in which different classes of compound should occur.It is hoped eventually to link the apparatus with a mass spectro- meter in order to confirm the nature of peaks already tentatively identified and to examine other peaks which we have, as yet, been unable to identify. Peaks already identified include those of : vanillic acid and vanilmandelic acid, from both adrenaline and noradrenaline ; homovanillic acid, from dopamine ; hippuric acid, from dietary benzoic acid conjugated with glycine ; and 5-hydroxyindoleacetic acid, from serotonin.Problems have been foundwith this part of the profile that arepossiblydue to thermal degradationof derivatives, and it is therefore not possible to present any data on these.Preliminary data processing has been carried out by use of an on-line link between the chromatograph amplifier and a programmable calculator. The calculator is programmed to accept the data via a digital voltmeter with BCD output, and uses the data to measure and print peak heights, with a correction for base-line drift.A recording system is currently being established, to permit the recording of the signal from the amplifier on an FM tape-recorder for subsequent data processing by the calculator and for storage or processing on the main univer- sity computer. It is anticipated that the storage of the chromatographic output will permit both qualitative and quantitative re-analysis of the data in the light of future findings.As an indication of the reliability of the technique, comparisons were made both of duplicate injections from the same sample vial and of injections made from duplicate preparations from the same urine sample. The over-all correlation coefficients were 0.99 for the same vial and 0.92 for the same urine. Both values were highly significant at a probability level of less than 0.1 yo.Steroids emerge a t the higher temperatures later in the analysis. The research described above was sponsored by the Leverhulme Trust with additional support from the Heinz and Anna Kroch Foundation. Reference 1. Dalgleish, C. E., Horning, E. C., Horning, M. G., Knox, K. L., and Yarger, K., Biochem. J., 1966, 101, 792.Analysis of Sulphonamides and Their Metabolites by Pyrolysis - Gas Chromatography - Mass Spectrometry J. A. Slack and W. J. Irwin Department of Pharmacy, University of Aston, Gosta Green, Birmingham, B4 7ET Pyrolysis can be defined as the transformation of a compound into another substance or sub- stances through the agency of heat alone. Usually this process leads to the production of a250 RESEARCH AND DEVELOPMENT TOPICS Proc.Analyt. Div. Ckem. SOC. range of smaller molecules, the identification of which may give valuable structural informa- tion concerning the parent molecule. The technique of analytical pyrolysis, which is particu- larly useful for the study of non-volatile compounds of high relative molecular mass, was pioneered by Zemanyl in 1952.In this work the pyrolysis of various polymers was studied and the pyrolysis fragments were passed directly into the source of a mass spectrometer (Py - MS). Although extensions of this method are under development, many useful results have been reported using gas chromatography to separate the pyrolysis fragments and to yield a characteristic pyrogram (Py - GC). The identification of the fragments is much facilitated by a gas chromatograph coupled to a mass spectrometer (Py - GC - MS).Various methods of pyrolysis are available2 and in the analysis of the sulphonamides we have used a Curie-point pyrolyser in which a small amount of the drug (50-100 pg) is coated on to the surface of a ferromagnetic wire. This wire is then rapidly heated by a radiofrequency-induced current to a set temperature (Curie Point), the value of which is dependent upon such factors as the composition of the wire and its diameter.3 The highly polar nature of sulphonamides has necessitated prior derivatisation for satisfac- tory analysis of these drugs by gas chr~matography,~~~ and therefore the relatively simple sample preparation required for Py-GC - MS is an immediate advantage.A small amount of the drug is suspended in a suitable solvent and then a known amount is transferred to a rotat- ing wire,6 which is held in a stream of warm air. On pyrolysis the products are flushed directly on to a Carbowax 20M plus potassium hydroxide column, which is programmed from 100 to 250 "C. Most of the medicinal sulphonamides studied underwent a simple fission and re- arrangement to yield aniline (present in all of the pyrograms) and a characteristic heterocyclic amine.For example, in the instance of sulphapyridine the products were identified as aniline and 2-aminopyridine. Exceptions to this general rule were seen with some of those sulphon- amides with methoxy substituents on the heterocyclic ring. In these instances the products of secondary rearrangements were observed, in which methylation of the aniline occurred to yield N-methyl- or N,N-dimeth~laniline.~ Sulphathiazole also underwent secondary re- arrangements to yield two minor peaks in addition to aniline and 2-aminothiazole.A disadvantage in using Py - GC - MS is that polar pyrolysis fragments may not be eluted. In order to test this possibility model sulphonamides, in which all anticipated pyrolysis products would be detectable, were prepared. Thus, using benzene sulphonanilide, small amounts of biphenyl and carbazole, together with trace amounts of diphenylamine, were indeed obtained but the processes yielding benzene and aniline were the major pathways.This result is in contrast to the fragmentation induced by electron impact (MS), in which the extrusion of sulphur dioxide is the major pathway.The analysis of formulated sulphonamides was also undertaken, with sample preparation identical to that of the pure drug. The excipients had no observable effect on the fragment- ation process, and on pyrolysis of a Sulphatriad tablet the resulting pyrogram was identical to that obtained by superimposing the pyrograms of the constituent drugs, i.e., Sulphadiazine, Sulphamerazine and Sulphathiazole.The use of Py - GC as a method for the quantitative assay of sulphonamides was also studied by utilising a further sulphonamide as an internal standard. Unacceptable errors were obtained when the analysis was carried out using temper- ature programming or during isothermal operation, when the peaks due to the heterocyclic amines exhibited undue tailing.Improved chromatography, which resulted in symmetrical peaks, was observed when the porous polymer packing Chromasorb 103 was used. A calib- ration graph of the ratio of the amounts of the sulphonamides on the wire against the ratio of the peak areas was then constructed. The fit obtained demonstrated that when testing an unknown sample an accuracy of better than 8% was not possible.The analysis by Py-GC - MS of sulphonamides and their metabolites in urine has also been undertaken using a sample preparation that is straightforward, with no extraction or derivat- isation procedures. An aliquot of urine is taken and a small amount freeze dried; the total solids obtained are then coated on to the wire and pyrolysed.The pyrogram obtained from a control urine sample is relatively simple, with no large interfering peaks in the area of interest. The urine from a patient undergoing sulphadimidine therapy showed three new peaks super- imposed on those of the control sample. These peaks were shown to be due to aniline and 2- amino-4,6-dimethyJpyrimidine from the unchanged drug, and acetanilide.The acetanilide was formed from pyrolysis of the major metabolite of sulphadimidine, which is the N-acetyl analogue. The technique is sufficiently sensitive to detect the excretion of those sulphonam-September, 1977 RESEARCH AND DEVELOPMENT TOPICS 251 ides used in low dosage. Thus, with urine obtained from a patient taking sulphamethoxy- diazine, the characteristic peaks were exhibited although in this instance these peaks were not the most intense ones in the pyrogram.The excretion of a triple sulphonamide was also followed by this technique with the constituents and their metabolites yielding clearly recognisable pyrograms. From these studies it can be seen that Py - GC - MS has potential for rapid analysis with no derivatisation procedures and the minimum of sample preparation.References 1. 2. 3. 4. 5. 6. 7. Zemanv, P. D., Analyt. Chem., 1952, 24, 1’709. May, R. W., Pearson, E. F., and Scothern, D., “Pyrolysis-Gas Chromatography,’’ The Chemical Simon, W., Kriemler, P., Voellmin, J. A., and Steiner, H., J . Gas Chromat., 1967, 5, 53. Blessington, B., Org. Mass Spectrom., 1972, 6, 347.Gyllenhaal, 0.. and Ehrsson, H., J . Chromat., 1975, 107, 327. Meuzelaar, H. C. L., and in’t Veld, R. A., J . Chromat. Sci., 1972, 10, 213. Irwin, W. J., and Slack, J. A., in Jones, C. E. R., and Cramers, C. A., Editors, “Analytical Pyrolysis,” Society, London, 1977. Elsevier, Amsterdam. 1977, p. 107. Determination of Sulphur Compounds of Biological and Medical Importance by Molecular Emission Cavity Analysis (M ECA) Mouayed 0.Al-Abachi Department of Chemistry. University of Birmingham, P.O. Box 363, Birmingham, B15 2TT MECA is a sensitive and rapid cool-flame technique that allows a wide range of non-metals to be determined.1-3 For example, sulphur compounds can be determined via their blue S, emission at 384 nm. A study of sulphur-containing drugs, amino acids and proteins has shown that such compounds are amenable to MECA, which thus provides a rapid means for their determination.An indirect method of determining carbonyl compounds has also been investigated. Drugs Drugs such as sulphonamides, phenothiazines and Busulphan give a blue S, emission in the MECA cavity. Organic solvents suppress the S, emission, probably because of simultaneous volatilisation of analyte and solvent.The solvent molecules and their decomposition frag- ments remove hydrogen atoms that are involved in producing S, emission. Pre-evaporation of solvent in a stream of hot air directed at the cavity eliminates the solvent effect. MECA characteristics, including t (time from introducing the cavity into the flame to that of maximum emission) values and linear calibration ranges are shown in Table I.The technique was applied to commercial drug samples. Promethazine hydrochloride, for example, was determined in tablets and injection solutions. Tablets were dissolved in water, and both the injection and tablet solutions were adjusted to pH 11.0 with sodium hydroxide before extraction with hexane and determination of the drug in the extract.The phenothiazines give a sensitive, fast emission (t, = 0.2 s), possibly owing to the rapid breakdown of the sulphur-containing ring to give a carbazole molecule with release of sulphur. The sulphonamides all have similar t, values (1 -4-2.4 s) . Various structural response correla- tions can be drawn. For example, the carboxyl group present in place of an NH, group in probenecid draws electrons away from the ring and weakens the sulphur bonding, thus result- ing in faster breakdown and a smaller t, value than for the other sulphonamides.Because of the difference in t, between the two types of compound, the MECA response of a sulphonamide can be resolved from that of a phenothiazine, so that both components (e.g., promethazine and sulphamerazine) can be determined in admixture.Some of the compounds have two sulphur atoms. Sulphathiazole has a sulphonamide group and a sulphur atom in a thiazole ring. The MECA response shows two peaks, t, = 0.5 and 2.1 s, which are character- istic of the thiazole and sulphonamide sulphur atoms, respectively. Two s, peaks were also There is a relationship between the structures of drugs and their MECA behaviour.252 RESEARCH AND DEVELOPMENT TOPICS Proc.Analyt. Div. Chem. SOC. found for acetazolamide. Busulphan has two equivalent sulphur atoms; a single MECA peak was observed. TABLE I MECA BEHAVIOUR OF SULPHUR-CONTAINING DRUGS Drug Promethazine Pcrphenazine Probenecid Dapsone Sulphamerazine Sulphaguanidine Sulphathiazole Ace tazolamide Busulphan Structure a;3 I A 0 N-N CH3-!-NHAS&SO~NH2 trnp 0.2 0.2 1.4 2.0 2.1 2.4 0.5, 2.1 0.9, 1.2 1.7 Linear calibration Limit of range detection (sulphur)/ng (sulphur)/ng 0.4-6.0 0.5-6.0 5-100 10-150 10-150 10-250 1-15 2.5-40 5-50 0.2 0.3 2.0 2.6 2.0 2.0 0.7 1.5 4.0 Coefficient of variation, % 2.5 2.3 3.1 1.7 2.2 5.0 1.5 4.0 2.8 Amino Acids and Proteins The MECA behaviour of the sulphur-containing amino acids and proteins, such as serum and egg albumins, has been studied on the basis of their S, emissions, and sensitive methods for determining nanogram amounts of these compounds have been developed (Table 11).The sensitivity was increased if the aqueous solvent was evaporated before inserting the cavity into the flame. Because taurine had a much larger t, value than the other amino acids, it was possible to obtain resolved MECA peaks from mixtures of taurine and another amino acid.September, 1977 Compound Methionine .. Cysteine .. Cystine* . . Pencillamine . . Clutathione . . Taurine .. Egg albumin . . Serum albumin RESEARCH AND DEVELOPMENT TOPICS TABLE I1 MECA DETERMINATION OF AMINO ACIDS AND PROTEINS tmp ... . 0.25 .. . . 0.5 .. . . 0.5 .. . . 0.25 .. . . 0.5 .. * . 1.4 .. . . 0.7 .. . . 0.7 Calibration range (sulphur) /ng 1-12 2-15 2-17 1-10 2-20 10-50 0.25-57 0.25-5t Detection limitlng per 5 pl 0.6 1.0 1.2 0.6 1.2 4 0 . l t 0 . l t 253 Relative standard deviation, % 2.5 4 3 2 3 4 6 6 * In the presence of orthophosphoric acid. t pg of protein. Aldehydes, Ketones and uic-Diols Trace amounts of aldehydes and ketones have been determined after reaction with an excess of sulphite ions.The free sulphite peak appears first, followed by that from the carbonyl- sulphite compound. The latter is a measure of the aldehyde or ketone concentration.* Acetone forms a weaker compound with sulphite and the peak is displaced less than that of formaldehyde, so that formaldehyde and acetone give resolved peaks, thus allowing the compounds to be determined simultaneously.This procedure can also be applied to the rapid determination of formaldehyde produced by the Malaprade oxidation of vic-diols. After oxidation with periodate, excess of sulphite is added; periodate and iodate oxidise some of the sulphite to sulphate, so that three MECA peaks are obtained, from free sulphite, the addition compound and sulphate.The author thanks the Ministry of Higher Education and Scientific Research, Republic of Iraq, for a scholarship, numerous pharmaceutical companies for providing drug samples, and particularly Dr. A. C. Caws, The Wellcome Foundation Ltd., for the provision of analysed samples. References 1. Belcher, R., Bogdanski, S.L., and Townshend, A., Analytica Chim. Acta, 1973, 67, 1. 2. Belcher, R., Bogdanski, S. L., Knowles, D. J., and Townshend, A., Analytica Chim. Acta, 1975, 77, 53. 3. Al-Abachi, M. Q., Belcher, R., Bogdanski. S. L., and Townshend, A., Analytica Chim. Acta, 1976, 86, 4. Al-Abachi, M. Q., Belcher, R., Bogdanski, S. L., and Townshend, A., Analytica Chim. Acta, 1977, 139. 92, 293. Some Investigations into the Electroanalytical Chemistry of Selenium S.Forbes and G. P. Bound The Macaulay Institute for Soil Research. Craigiebuckler. Aberdeen, AB9 2Q J Selenium has many applications, being used as a decolourising agent in glass manufacture, to improve the machineability of steels, as a rubber-curing agent and to formulate insecticides, lubricants and pharmaceuticals. The discovery of selenium as an essential element1 that is necessary for the prevention of white muscle disease2 led to the development of many analytical methods for determining selenium.In Northern Scotland selenium-deficient soils are wide- spread, requiring the addition of selenite- and selenate-enriched fertilisers. Very sensitive techniques are necessary in order to study the interaction of selenium, selenides, selenite, selenate and organoselenium compounds in the soil and their effect on selenium uptake by plants.Neutron activation analy~is,~ gas chr~matography,~ spectroscopic5~6 and electro- chemical' methods have been reported for measuring selenium at the sub-parts per million level and this paper describes work carried out on the determination of selenium by differen- tial pulse polarography and cathodic stripping voltammetry.254 RESEARCH AND DEVELOPMENT TOPICS Proc.Analyt. Div. Chem. SOC. The electrochemistry of selenium can be loosely divided into reactions that take place in acidic media and those occurring in basic electrolytes. In acidic media two polarographic waves are observed corresponding to the 4-electron and 2-electron reductions : H2Se0, + 6H+ + 6e + H,Se + 3H20 .. .. .. (1) Hg + H2Se+ HgSe + 2H+ + 2e . . .. (2) Net reaction: H2Se0, + 4H+ + 4e + Hg --+ HgSe + 3H20 . . . . .. (3) HgSe + 2H+ + 2e-+ Hg + H2Se . . .. .. (4) H,SeO, + 6H+ + 6e - H,Se + 3H20 . . .. .. (5) At pH>3 a 6-electron reaction also occurs: If metals such as copper, lead or iron are present in the polarographic cell they will be precipitated as selenides upon reduction of Se(1V ) to Se( -11) [reaction (l)].Consequently, the waves observed for reactions (3) and (4) in acidic media are affected by common metal ions and these interferences must be removed prior to analysis. Alternatively, polarograms can be recorded in basic electrolytes and the 6-electron wave measured [reaction ( 5 ) ] , which is independent of these ions.Differential Pulse Polarography of Selenium(1V) The behaviour of Se(1V) at a dropping-mercury electrode was studied in sodium sulphite, phosphate - citrate buffer, ammonium chloride and ammonium acetate electrolytes. The last two solutions gave a well resolved selenium peak at 1 M salt concentrations. Peak potential was found to be solely dependent upon pH and the best separation was achieved at pH 8.0 (EP -1.34 V vers~us S.C.E.).Copper, lead and iron(II1) ions had no effect on peak height when present in 1000-fold excess but peak overlap was observed for several ions, especially in ammonium chloride electrolyte. In ammonium acetate only zinc (EP -1.38 V vcrszu S.C.E.) had a similar peak potential to that of selenium, but this was removed by the addition of EDTA (0.01 M) to the electrolyte.Certain organic compounds present in soil extracts might also be reduced a t similar poten- tials but only furfuraldehyde, a degradation product of polysaccharides, was detected. Acidic hydrolysis (with 10% nitric acid) followed by neutralisation was sufficient to remove the overlapping furfuraldehyde peak.Soil extracts were obtained by shaking air-dried soil (1 g) with water (20 ml) for 4 h followed by filtration. The extracts were centrifuged and the back- ground electrolyte added prior to analysis. Recovery of added selenium from these extracts was quantitative and by using this method the adsorption characteristics of the selenite ion in three different soils were studied.The detection limit of 0.025 p.p.m. that can be achieved by differential pulse polarography is not sufficiently sensitive to study the uptake of selenium in deficient soils and so analysis by cat hodic st ripping volt ammet ry was investigated. Differential Pulse Cathodic Stripping Voltammetry of Selenium( IV) Voltammograms of Se(1V) in 0.1 M perchloric acid, recorded a t a hanging mercury drop electrode, exhibit two peaks corresponding to reactions (3) and (4).On addition of a halide ion the first peak increases in heights owing to the formation of a hexahaloselenium complex, which is adsorbed on to the mercury drop. Thus, Se(1V) in acid - halide solutions can be determined by differential pulse cathodic stripping voltammetry at a hanging mercury drop electrode.The optimum conditions for analysis are presented in Table I. TABLE I OPTIMUM CONDITIONS FOR THE DETERMINATION OF SELENIUM( IV) BY DIFFERENTIAL PULSE CATHODIC STRIPPING VOLTAMMETRY Scan direction : negative Modulation amplitude : 25 mV Deposition time: 3 min (stirred) HMDE: 3 div drop-l Initial potential: -0.05 V Pulse frequency: 2 Hz Scan rate: 2 mV s-1 and 30 s (quiescent)September, 1977 RESEARCH AND DEVELOPMENT TOPICS 255 Voltammograms recorded for different strengths of hydrochloric acid electrolytes gave maximum stripping currents at a concentration of 1% V/V (approximately 0.1 M hydro- chloric acid).The peak current measured at -0.54 V versus S.C.E. [corresponding to reac- tion (a)] was proportional to the selenium concentration over the range 0.01-0.15 p.p.m., with a detection limit of 0.5 p.p.b.An addition of 0.02 p.p.m. of selenium thus ensured that all measurements were made on the linear region of the calibration graph. Addition of 0.02 p.p.m. of copper to a solution containing 0.02 p.p.m. of selenium suppressed the peak at -0.54 V by approximately 50%. Thus, metals which precipitate as selenides in acidic media should be removed before undertaking cathodic stripping analysis of selenium. Masking of copper in the polarographic cell with benzotriazole (C,H,-NH-N:N), potassium thiocyanate and EDTA was unsuccessful.Extraction with dithizone (C,H,.N:N.CS.NH. NH.C,H,) in carbon tetrachloride was fruitless as the complexone also reacted with selenium. It was possible, however, to remove copper with no retention of selenite after passage through Amberlite IR-l20(H) cation-exchange resin (BDH Chemicals) at pH 3.54.0.- Application of Differential Pulse Cathodic Stripping Voltammetry of Selenium( IV) to Soils and Plant Materials Wet-digestion techniques for soils and plant materials usually require the use of perchloric acid. Because of the hazards associated with perchloric acid in the laboratory, oxygen-flask digestions were employed for the analysis of soils and plant materials.Although slower than wet-digestion methods the oxygen flask has the advantage that the volatile selenium is separated from the ash in which the interfering metals are retained. Quantitative recoveries of Se(1V) in the oxygen flask were only possible when strongly oxidising solutions were used as collecting agents.Radiotracer studies were carried out with selenium-75 labelled methionine pipetted on to cellulose pellets and burnt in the flask. The volatile constituents were collected in both water (35 ml) and a solution of saturated potassium persulphate (25 ml) with concen- trated sulphuric acid (10 ml). The recoveries obtained in water were 77, 67 and 70% (mean, 71.3y0), and in persulphate - sulphuric acid were 100, 100 and 95yo(mean, 98.3%). As the persulphate - sulphuric acid mixture oxidises selenium to the Se(V1) state it was necessary to treat the collecting agent with two 5-ml aliquots of concentrated hydrochloric acid and to heat the solution for 30 min on a low-temperature hot-plate.This treatment destroyed any excess of persulphate and reduced Se(V1) to Se(1V).Thedigest was diluted to volume and ammonia (sp.gr. 0.88) added to an aliquot of this solution until the pH, measured by use of a glass electrode, had increased to 3.5 (k0.2). The sample (5 ml) was deoxygenated and concentrated hydrochloric acid (50 pl) and Se(1V) (0.02 p.p.m.) were added before recording the voltammogram and measuring the stripping peak at -0.54 V veysus S.C.E.A calibration graph was constructed in a similar manner by burning cellulose pellets doped with Se(1V) in the oxygen flask and subsequently analysing them by differential pulse cathodic stripping voltammetry. Results obtained for two soils and 18 plant materials by use of this method were compared with the concentrations found by using the spectrofluorimetric m e t h ~ d .~ Statistical analysis of the data gave a correlation coefficient of 0.98 between the two techniques. Some discrepancies occurred at verylow concentrations of selenium owing to the high blank encounteredwhen using the fluorimetric method but the detection limit of 0.005pg g-l was the same for both techniques. Application of Differential Pulse Cathodic Stripping Voltammetry after Hydride Generation By maintaining the hanging mercury drop electrode at a potential more positive than the potential at which reaction (4) occurs in a solution containing hydrogen selenide it is possible to accumulate selenium on the surface of the electrode.This selenium can then be removed by cathodic stripping and the 2-electron reduction wave observed.Hydrogen selenide, produced by the action of sodium borohydride on acidic selenite solutions, was swept with nitrogen into a solution of 0.05 M sodium hydroxide, 0.1 M potassium nitrate and hydrazine in the polarographic cell. The electrode was held at -0.8 V VEYSUS S.C.E. and, after accumulat- ing selenium for a specified time (2.5 min in this study), the stripping voltammogram was recorded.A well resolved selenium peak occurred at -0.94 V VeYsus S.C.E. but calibration256 RESEARCH AND DEVELOPMENT TOPICS Proc. Analyt. Div. Chem. SOC. graphs exhibited a “saw-tooth” response between selenium concentration and peak current. This phenomenon probably resulted from a surface effect on the hanging mercury drop electrode, such as the completion of successive monolayers, and so the hydride-generation method appeared to be unsuitable for selenium determination by cathodic stripping volt ammetry.S. Forbes thanks the SRC for the provision of a research studentship. 1. 2. 3. 4. 5. 6. 7. 8. References Schwarz, K., and Foltz, C. M., J. Am. Chem. Soc., 1957, 79, 3292. Tagwerker, F. J., J . Agric. Vet. Chem., 1960, 1, 23 and 78.Kronberg, 0. J., and Steinnes, E., Analyst, 1975, 100, 835. Shimoishi, Y., Analyst, 1976, 101, 298. Olson, 0. E., J. Ass. 08. Analyt. Chem., 1969, 52, 627. Vijan, P. N., and Wood, G. R., Talanta, 1976, 22, 1. Blades, M. W., Dalziel, J . A., and Elson, C. M., J . Ass. 08. Analyt. Chem., 1976, 59, 1234. Vajda, F., Acta Chim. Acad. Sci. Hung., 1970, 63, 257. Determination of the Subcellular Distribution of Mercury in a Penicillium spp.by Gel-permeation Chromatography and Transmission Electron Microscopy - X-ray Energy Microanalysis W. R. Simpson* Department of Inorganic Ghemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol P. F. Heap and G. Nickless Department of Anatomy, The Medical School, University of Bristol, University Walk, Bristol Department of Inorganic Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol Little attention has been paid to interactions of mercury with micro-organisms in the terrestrial environment.Hence a programme of work was initiated in order to (i) isolate mercury-tolerant fungi from mercury-contaminated soils, (ii) submit organisms from (i) to growth studies in media containing from 0 to 100 p.p.m.of Hg2+ and (iii) determine the mode of tolerance of organisms from (ii) in terms of volatilisation of mercury, binding of mercury to soluble cytoplas- mic proteins and binding of mercury by the insoluble fractions of the cell, e g . , cell wall and cell membrane. Most of this paper is concerned with the mode of tolerance of one particular organism, an unidentified Penicillium spp., although first it is necessary to give a brief outline of the isolation and tolerance procedure [i.e., points (i) and (ii) above].Isolation, Tolerance and Growth Studies Twelve soil samples were taken from the vicinity of the mercury mines in Almaden, Spain. The mercury levels in the <40-pm particle size fraction varied from 5 000 p.p.m.near the mine to 80 p.p.m. 24 miles from the mine. From each of the samples was taken 1 g of soil, which was diluted 10 000-fold (1 ml of a 1 g per 100 ml suspension diluted 100-fold) and 1 ml of the resulting solution was spread on to Rose Bengal- streptomycin plates.1 By this method, the cultures grow as discrete colonies, which facilitates subculturing.Each of the 189 cultures so obtained was transferred to stock plates for identification and on to plates containing 100 p.p.m. of mercury as the chloride for tolerance screening. Twenty species were tolerant to mercury at this concentration and spore suspensions of each of these cultures were inoculated into four separate 250-ml Erlenmeyer flasks containing 100 ml of culture medium.After 2-7 d, mercury as the chloride was added to three of the flasks to give final concentrations of 1 , l O and 100 p.p.m., the remaining flask acting as a control. After a further week’s growth, the cultures * Present address : Welsh National Water Development Authority, Marine Laboratory, Ponthir Treat- ment Works, Ponthir, Gwent, NP6 1PG.September, 1977 RESEARCH AND DEVELOPMENT TOPICS 257 were harvested, dried and weighed. A peak in the plot of mass of culture versus Hg2+ con- centration was noted at 1 or 10 p.p.m.in nearly all instances. Eight of the isolates were selected for protein and volatilisation studies. 3 s w 2 m % ? ;ij= Q, s P" 3s d- Cdw - Q , Protein and Volatilisation Studies The procedure for the isolation of soluble cytoplasmic mercury-binding proteins was as follows.Growth. This was effected in 400ml of culture medium in 1-1 Erlenmeyer flasks on an elliptical shaker for 7-10 d at 20 j, 2 "C, with Hg2+ (50 p.p.m.) as the chloride. Homogenisation. Up to 12 g were homogenised in a Hughes press (from the Department of Microbiology, University College, Cardiff) at -25 "C. Centrifugation. To the homogenate were added 40 ml of 0.001 M Tris (pH 8.6) at 4 "C and the cell debris was spun down at 17 000 rev min-l at 4 "C.Ultrajiltration. The supernatant was concentrated to 1 ml in an ultrathimble of exclusion >20 000 relative molecular mass (Mr) . Freeze drying. The supernatant from the ultrafiltration was concentrated to 1 ml for studies on the Mr < 20 000 fraction. Gel-permeation chromatography.The gels used were Sephadex G-200 for the ultrafiltration concentrate and Sephadex G-50 for the freeze-dried fraction. The flow-rate was 15 ml h-1 at 4 "C in 0.001 M Tris on a 90 x 2.5 cm column bed. The eluate was collected in 5-ml fractions. Fraction analysis. Cold-vapour atomic-absorption spectrophotometry (CVAAS) and ultraviolet spectroscopy at 210, 250 and 280 nm were used.The Hughes press was the only means of achieving complete homogenisation. The ultra- filtration - freeze-drying step eliminated the need for an initial separation according to relative molecular mass on Sephadex G-75 gel. The method of CVAAS has been described previously2 and was originally developed specifically for mercury-binding protein analysis as an alterna- tive to the use of radioactive-tracer techniques.A typical spectrum obtained by gel-permea- tion separation is included in that paper.2 Two facts became apparent from this work: firstly, mercury is bound to the heavy (Mr > 100 000) and light (Mr < 3 000) protein fractions, and secondly, only 2% of the added mercury was bound to soluble cytoplasmic proteins (Table I).Further attempts to separate --Culture 12.725 g 0.89 g 1 000 9 ml All 100 Trap Glassware - 500 {wet mass) - Pellet 8.08g 5.30g 1 000 from cent- (wet mass) TABLE I RECOVERY STUDIES Penicillium spp., Czapek's-Dox medium* (400 ml), 10-d growth, 20 f 2 OC, Hg2+ at 50 p.p.m. Injection Hg in volume/ injection/ ml ng 0.1 55.75 0.1 49.5 0.01 130 0.01 41 0.01 71 0.02 70 0.5 - Hg con- centration, p.p.m.17.03 (13.94 + rinse) 556.1 1340 1260 - Total Hg/ Recovery, Pg % 6 133 31 7 707 35.4 1300 6.5 2 050 10.25 83.15 - - 10824] 52.5 10 172 J 400 2 102.25 -- * NaNO,, 3.g; K,HPO,, 1 g ; MgSO,, 0.5 g ; KC1, 0.5 g; FeSO,, 0.01 g; sucrose, 30 g ; water, 1 000 g; plus 1 ml of essential trace element solution (containing Zn2+, Mn2+, Cu2+, Mo,~,,~-, Fe3+) ; Hg2+ as chloride added later.258 RESEARCH AND DEVELOPMENT TOPICS Proc.Analyt. Div. Chem. SOC. the mercury-binding proteins of M , < 3 000 by gradient elution on DEAE-Sepharose CL-6B on various gradients between 0.001 and 0.5 M Tris (pH 8.6) failed, in that the mercury was removed from the protein fractions by the ion exchanger. The extent of volatilisation was determined by passing air over the culture medium and trapping exhaust gases in concentrated nitric acid.A Dreschel head was inserted into the culture flask such that the probe end was about 2 cm above the medium and the air flow from the cylinder was controlled by a peristaltic pump. Nitric acid (10 ml) was contained in a 12.5-ml glass tube connected to the exit of the Dreschel head by sub-seals and PVC capillary tubing.The PVC tubing from the flask was immersed in the acid and a flow of one bubble every 10 s was maintained by the pump. A hole was pierced in the seal of the acid tube to allow flow. From Table I it can be deduced that: 1. volatilisation was low; 2. digestion of the culture was incomplete, as illustrated by the difference between the pellet and culture recoveries ; and 3.either the cell wall or the internal membranes and organelles bound the mercury rather than soluble cytoplasmic proteins. To clarify the last point on the distribution of mercury in the cell, transmission electron microscopy was used in conjunction with X-ray energy spectroscopy. Transmission Electron Microscopy (TEM) - X-ray Microanalysis The treatment of the specimen of Penicillium spp.prior to examination was as follows. Fixation. Paraformaldehyde (0.5 ml) was mixed with water (13 m1) and heated to 70 "C. Sodium hydroxide solution was added dropwise to clear the solution, followed by sodium cacodylate (33 ml, 0.1 M) and glutaraldehyde (4 ml). Sucrose (1 g) and calcium chloride (25 mg) were added in order to maintain osmotic pressure and ionic strength, respectively.Samples of culture grown with and without mercury were suspended in the fixative. Changes of fixative were made at 0.5 and 2 h. Osmium fixation (osmium tetraoxide, 0.1 M) for phospho- lipids and fats was used for normal morphological examination, but was avoided with mercury samples because of interferences by osmium in the X-ray spectra and the masking of electron- dense deposits produced by mercury alone.Dehydration was achieved by treating the samples with ethanol of increasing concentration (30, 50, 70, 80 and 95%, 10 min each, and absolute ethanol, four times, 15 min each) and finally twice with propylene oxide (15 min each). Embedding. Embedding was carried out with Spurr resin by replacing half of the propylene oxide with resin (0.5 h), then half this mixture with a further aliquot of resin (0.5 h), followed by three complete changes at 12-h intervals.The pellets were removed, partially dried, sunk into fresh resin contained in moulds and polymerised at 70 "C for 7.5 h. The embedded pellets were cut from the blocks, shaped and sectioned on an LKB ultramicrotome. Sections with a thickness of 60nm were cut for morphological examination and of 100 nm for examination by TEM - X-ray probe microanalysis, the sections being mounted on copper and carbon - nylon support grids, respectively. TEM - X-ray probe microanalysis was conducted with a modified Hitachi HU-11B trans- mission electron microscope fitted with both a cold-stage facility and a Kevex X-ray energy spectrometer.Morphological examination of the sections of mercury-containing cultures showed the presence of electron-dense deposits on the cell walls of the fungi and on extracellular filamentous material. No such deposits were observed for cells grown in the absence of mercury. X-ray analysis of the electron-dense deposits for the presence of mercury initially was found to be unsatisfactory under normal operating conditions of the instrument because, after an analysis time of 20 s the developing spectral energy peak for mercury at 2.224 keV (M line) was obscured by ever increasing background levels, The loss of mercury from the sample was attributed to diffusion and sublimation arising from the reducing and heating effect of the electron beam aided by the operating vacuum.In order to overcome this problem, the sections were cooled to -130 "C with the cold-stage facility (liquid nitrogen) and subsequent analysis of the electron-dense deposits produced clear X-ray energy spectral peaks for mercury at 2.224 keV (M line) and at 9.987 and 11.821 keV (La and L/3 lines).An expanded spectral peak following background subtraction for the M line of mercury at Dehydration.Sectioning.September, 1977 RESEARCH AND DEVELOPMENT TOPICS 259 2.224 keV is shown in Fig. 1. No confusion is seen between this value and sulphur, which has a Ka value of 2.32 keV. Additional confirmation of the presence of mercury in the electron- dense product was provided by the presence of the La and Lp lines for that element. The Fig. 1. Expanded X-ray spectra of the mercury peak of the M line following background subtraction.Net X-ray count of 1393 counts; energy centroid of the peak set a t 2.224 eV (top line of data display) using 11 channels for X-ray collection. application of the cold stage to provide a solution to the problem of the identification of mercury, using X-ray probe microanalysis, was further demonstrated when a comparison of diffraction patterns from a sample of mercury(I1) chloride was made at normal operating temperatures (no pattern) and a t -130 "C (clearly defined rings).Discussion Experiments on the soluble cytoplasmic proteins showed that only about 2% of the total mercury added was bound to these proteins. There was no evidence for the presence of mercury metallothionein equivalent to the copper metallothionein found in Saccharomyces ce~evisiae.~ The maximum culture mass for 1 or 10 p.p.m.of added mercury gives support t o the suggestion of interference in normal membrane permeability (e.g., refs. 4 and 5 ) . TEM examination revealed some disintegration of the cell wall, which was noted in the form of extra-cellular filaments. Mercury was positively identified as being bound to the cell wall by TEM - X-ray energy spectroscopy. Satisfactory spectral peaks for mercury were obtained only by the use of a nitrogen-cooled cold stage at -130 "C to retard volatilisation of mercury.Sulphur (Ka line at 2.32 keV) did not interfere in the identification of that element (M line at 2.224 keV) and additional confirma- tion was obtained with the presence of mercury La and Lp lines at 9.987 and 11.821 keV, respectively.A fully illustrated paper is in course of preparation.6 Thanks are due to Dr. R. E. Campbell and Dr. M. F. Madelin of the Department of Botany for their valuable assistance. References 1. Martin, J. P., Soil Sci., 1950, 69, 215. 2. Simpson, W. R., and Nickless, G., Analyst, 1977, 102, 86. 3. Prinz, R., and Weser, U., Hoppe-Seyler's 2.Physiol. Chew., 1975, 356, 767. 4. Passow, M., and Rothstein, A., J . Gen. Physiol., 1960, 43, 621. 5;. Murray, A. D., and Kidby, D. K., -1. Gen. Microbiol., 1975, 86, 66. 6. Heap, P. F., Simpson, W. R., and Nickless, G., submitted for publication.260 RESEARCH AND DEVELOPMENT TOPICS Proc. Analyt. Div. Chem. Soc. Use of PVC Membrane Type Calcium Electrodes for Continuous Automatic Analysis C.R. Loscombe and J. A. W. Dalziel An electrode of the Moody and Thomas type,l based on the Orion calcium liquid exchanger (92-20) immobilised in a PVC membrane, has been used for continuous automatic analysis, in which it functions as a dynamic sensor. The flow cell was constructed from Perspex (Fig. 1). The reference electrode was a conven- tional Orion single junction (Model 90-Ol), held in place by a PTFE sleeve.The calcium electrode comprised the body, containing a M calcium chloride solution with a silver - silver chloride wire as internal reference, which screwed down on to a rubber O-ring that held the PVC membrane in place in the cell. The volume under each electrode was of the order of 1 ml. Signal noise, caused by pulsing of the proportioning pump, was low when the reference electrode was placed before the calcium electrode in the reagent stream, probably because the volume of the reference compartment acted as an expansion chamber for the sensor.A bubble chamber was incorporated to isolate the cell electrically and the response was measured on a recording millivoltmeter (Corning-EEL, Model 12).This assembly was used toinvestigate the automated determination of total calcium in potable waters. Department of Chemistry, Chelsea College, Manresa Road, London, SW3 6LX To pH meter Orion ref. electrode - NO. 90-01 0.01 M CaCI2 soln. saturated with Ag Cl PTFE sleeve \ 1 - 1 I +2.5cm-+ Fig. 1. Calcium electrode assembly. To de-mask the calcium complexed by carbonate, samples were simply acidified to pH 4-5 by dropwise addition of dilute hydrochloric acid to a stirred solution. Approximately 3-ml portions of these acidified water samples were placed in cuvettes in a Carlo Erba sample distributor, where their acidic nature prevented further attack by atmospheric carbon dioxide.A proportioning pump was used to mix these samples 1 + 1 with a buffer, followed by air segmentation and passage through a single-mixing coil and de-bubbler before reaching the electrode flow cell (Fig.2). The buffer employed contained 0.1% V/V triethanolamine2 in order to maintain pH and constant ionic strength. M with respect to calcium chloride; the addition is important as it improves the sampling rate and reduces base-line drift.With this system the electrode response was 25mV per decade over the range 10-4-10-2~ calcium chloride. Interference between successive peaks was minimal, with a sample time of 2 min and a wash time of 8 min (k, a maximum of about six samples per hour) (Fig. 3). This sample time corresponds to 60-70% of the equilibrium response but replicate analyses are repro- ducible, with a coefficient of variation of peak height of 3.7%.Both sodium and potassium This buffer was madeSeptember, 1977 To waste A RESEARCH AND DEVELOPMENT TOPICS Bubble chamber 1 Fraction distributor 261 I I - _ . . rroporrioning pump Fig. 2 . Flow diagram for automated calcium electrode. ions interfere more with the calcium electrode in this automated mode than in more con- ventional static measurements in which the full equilibrium response is measured. An important factor in the use of PVC-membrane electrodes as sensors in automated systems is the lifetime of the membrane.In the present study, discs were used on a part-time basis for up to 14 weeks with a total of 170 working hours. The response curves changed only slightly during this period. In full-time use the system would probably require a new membrane _.'every-2-3 weeks. A 10-3 1 0 - ~ 1 0 - ~ 10-3 lo-: 4x lo-? 4x I 0-3 W n Fig. 3. Response of automated electrode. The results obtained from the duplicate analysis of ten water samples using both the automa- ted system and a more conventional atomic-absorption method, employing a lanthanum buffer, are given in Table I. All of the samples fell within the concentration range of the automated method and the only pre-treatment necessary was the acidification step.At the low calcium levels found for samples 3 and 8 the enhancement caused by sodium and potassium interference gave rise to poor agreement between the two methods; for these two samples, flame emission analysis gave 122 and 124p.p.m. of sodium, respectively. At higher calcium levels the agreement was satisfactory.The automated electrode cell has also been tested with a copper ion-selective electrode based on a dialkyl dithiophosphate analogue of the calcium exchanger, which has similar response characteristics. From the investigations so far we conclude that the automation of PVC-262 RESEARCH AND DEVELOPMENT TOPICS Proc.ArtaZyt. Div. Chew. SOC. TABLE I TOTAL CALCIUM IN POTABLE WATERS Sample No. 1 2 3 4 5 6 7 8 9 10 Calcium, p.p.m. r Automated Atomic-absorption electrode spectrophotometry A \ 47 48 71 67 17 5 108 111 19 15 27 29 107 122 19 1 82 88 128 140 membrane electrodes may have limitations, such as relatively slow rates of sampling and, for the calcium electrode, increased interference by sodium and potassium ions. However, the system has proved simple to operate for the determination of total calcium and it should be possible with further work to make more use of the special advantage of electrodes as sensors, which is their ability to measure free to bound ratios.References 1. Moody, G. J., Oke, R. B., and Thomas, J. D. R., Analyst, 1970, 95, 910. 2. Bailey, C.A. M., PhD Thesis, University of London, 1973. Application of Continuous Water-quality Monitoring to the Study of a Grossly Polluted Stream L. Ebdon G. M. Doughtyand 6. P. Hafferty Department 0-f Chemistry, Shefield City Polytechnic, Shefield, S1 1 WB Department of Civil Engineering, Shefield City Polytechnic, Shefield, S1 1 WB The increased awareness of environmental pollution together with the rising demand for water for industrial, recreational and domestic purposes, has led to a greater emphasis on the study of the quality of water.This study has traditionally been performed with the aid of discrete or “snap” sampling programmes with subsequent analysis in the laboratory. Such sampling programmes have several inherent disadvantages, e g . , monthly or weekly samples represent only a minute part of the river flow, no information is obtained about sporadic discharges or periodic variations and no warning of the deterioration of water quality is obtained. A continuous water-quality monitoring station, suitably sited, regularly maintained and with appropriate data-acquisition facilities, can reduce many of these shortcomings.The development of such stations has been closely associated with advances in the fields of instrumental analytical chemistry and computerised data handling.Some continuous monitors require suitable chemical reactions before measurements are made,l but those which do not are capable of submersible operation as well as land-based operation.2 In the work described here a land-based monitor of the second type was used.Continuous monitoring generates far more data than discrete monitoring and hence in- creased reliability can be placed on any conclusions based on the data. Usually, the handling and analysis of such large amounts of data must be performed by computer, but with this come the possibilities of rapid response to quality deterioration and the construction of mathe- matical models with predictive capability.Mathematical models can be of the steady-state type,3 relying upon generalised empirical coefficients being determined from, for example, yearly mean and percentile data, while others are dynamic modelsI4 which are capable ofSeptember, 1977 RESEARCH AND DEVELOPMENT TOPICS 263 accepting time-varying input functions of the various determinands and operating upon them to predict output responses. Dynamic models are thus best based on large amounts of data and continuous monitors are well suited to providing this.While any model should be treated with caution, generalised ideas of how a system functions are extremely valuable. The Monitoring Programme A grossly polluted stream flowing through an essentially urbanised environment for approx- imately 13 km was chosen for study. The catchment is heavily industrialised and also carries a motorway.The main pollution problems stem from a grossly overloaded and, in places, a damaged combined sewage system, Storm-water overflows, designed to discharge excess flow from the sewers to the stream during storm conditions, operate during dry weather in some instances.Thus, untreated domestic sewage and industrial effluents discharged to the sewer may enter the river system. A new relief trunk sewer is now under construction in the valley. The apparatus primarily used in the research project was a Plessey MM5, Land-based Continuous Water Quality Monitoring Station (WQMS) (Plessey Radar, Weybridge, Surrey, England).This self-contained equipment contains all the necessary hydraulic and electronic systems and was operated for 20 months. The station was installed in a purpose-modified site caravan within an industrial location. The original submersible pump supplied with the WQMS proved to be unreliable in these particular conditions and it was replaced by a mono-pump mounted within the caravan.The following determinands were monitored at quarter-hourly intervals : dissolved oxygen, electrical con- ductivity, pH, suspended solids and temperature. An automatic cleaning cycle was operated daily and manual cleaning performed weekly, with sensor calibration being performed at the same time. The level of accuracy and the reliability obtainable were found to be dependent upon regular cleaning.On commencement of the automatic data-acquisition cycle water was pumped around the sensor blocks for 3 min and then the quality data recorded in three ways: on magnetic tape, on chart paper and on visual display meters. The cycle was then automatically terminated. A facility for collecting an “alarm sample,” when any determinand exceeded a pre-set alarm level, was also available.A number of problems had to be overcome before the WQMS could be successfully operated routinely. The original submersible pump was particularly affected by the acidity, the high content of suspended solids and the wide depth variations encountered in the stream. The sensors and hydraulic system also tended to block; hence the emphasis upon regular cleaning.The charger for the batteries that operated the station also gave some problems initially and it was found advisable to have spares available. A flow-gauging station, comprising a continuous depth recorder calibrated against a double- crested weir, was constructed and sited upstream of the WQMS. Stream flows prior to the installation of this gauge were estimated from unit hydrograph t h e ~ r y . ~ Rainfall in the catch- ment was also monitored continuously. The continuous monitoring programme has been supplemented by weekly discrete sampling at eight sites upstream of the WQMS. These samples were analysed for the five station determinands, BOD, COD, ammonia and heavy metals. Biological parameters have also been investigated. Microscopic examination has indicated no plant or animal life other than occasional sewage-sludge protozoans in the water at the station. Microbiological examination confirmed the presence of large numbers of intestinal bacteria. Mains electricity was also available. Data Handling and Model Building The data recorded on magnetic tape was transposed on to punched paper-tape, decoded and stored on cards and disc files appropriately time referenced. Initial analysis was performed on mean hourly data. In the development of the model attention was paid to relationships, observed from the chart recordings, between determinands. For example, dissolved oxygen appeared to rise as pH fell but to fall as suspended solids increased. There are many diverse inputs to the stream, e.g., surface and ground water, storm-water overflows, tributaries, motorway run-off, industrial-process and cooling effluents. The tot a1 inputs are obviously unmonitorable but it was thought possible to design a model in which a264 EQUIPMENT NEWS PYOC. Analyt. Div. Chem. SOC. given parameter could be predicted from a knowledge of other parameters and the relationships observed. The most effective method of analysing these inter-relationships has been by multiple-regression analysis. Fig. 1 shows how the dissolved-oxygen level can be predicted from a knowledge of pH and suspended-solids content only, and compares this level with the observed values. Work is continuing on improving this model and reducing the standard error by the inclusion of other variables, including discretely monitored and ergonomic data. Fig. 1. Comparison of observed (solid line) and predicted Independent variables : (broken line) dissolved oxygen levels. pH and suspended solids. It is hoped that a dynamic water-quality model with a general predictive capability will be produced, thus further emphasising the value of automatic continuous monitoring in the study of water quality. We thank the Science Research Council for the award of a studentship to one of us (BPH). References 1. 2. 3. Kamphake, L. J.. and Williams, R. T., Adv. Autom. Anal., Technicon Int. Congr., 1973, 8, 43. Eriggs, R., Proc. SOC. Wat. Treat. Exam., 1975, 24, 23. Newsome, D. H., Bowden, K., and Green, J. A., in “Symposium on Advanced Techniques in River Basin Management. The Trent Model Research Programme,” The Institution of Water Engineers, London, 1973, pp. 151-159. Beck, M. B., Wat. Res., 1976, 10, 575. Viessman, W., Harbaugh, T. E., and Knapp, J. W.. “Introduction to Hydrology,” Intext Educational 4. 5. Publishers, New York, 1972.

ISSN:0306-1396    

DOI:10.1039/AD9771400248

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

264 Equipment EQUIPMENT NEWS Automated Melting-point Apparatus Gallenkamp announce the Mettlcr FP61 for the automatic determination of me1 ting-point, which operates by passing light through the sample. The melting-point is taken to be the tempera- ture at which a factory-set constant threshold of translucency is reached. The rate of heating can be pre-set and the digital read-out is accurate to 0.1 "C.A. Gallenkamp & Co. Ltd., P.O. Box 290, Christopher Street, London, ECBP 2ER. Fluorescence Detector A new fluorescence detector for liquid chroma- tographs, the LC-1000, is available. A xenon PYOC. Analyt. Div. Chem. SOC. source provides a continuum over the ultraviolet - visible region. Over the range 390-750nm a continuous interference filter is used as an emission monochromator.Below 390 nm a fixed interference filter can be used. The ability to scan the emission spectrum of a peak makes peak identification possible. Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Bucks., HP9 1QA. Liquid Chromatographs A range of modular liquid chromatographs, the Series 2, enables the user to tailor the equip- ment to the work required by adding furtherSeptember, 1977 EQUIPMENT NEWS 265 modules to the basic Series 2/1.Series 211 is a single module, designed pri- marily for routine quality control, while the Series 2/2, with expanded capabilities, will meet the needs for analytical-methods development, problem solving and research applications. The series complements the Model 601 research-grade liquid chromatograph.Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Bucks., HP9 1QA. Centrifuge The Eppendorf Centrifuge 5412 is for the fast separation of precipitates and of fluids of different specific gravities. Twelve holes on the rotor accept 1.5-ml Eppendorf micro-test-tubes and, with adaptors, the smaller 0.4-ml test- tubes. Anderman & Co. Ltd., Central Avenue, East Molesey, Surrey, KT8 OQZ.Temperature Programmer A digital indicating universal temperature programmer is announced. I t is designed for the accurate control of temperature or other parameters that require linear variation with time. A temperature range of -200 to 1 500 "C can be covered by various options, with heating rates of 1-99 "C min-1 or 0.1-9.9 "C min-1. Stanton Redcroft, Copper Mill Lane, London, SW17 OBN.Atomic-absorption Spectrophotometer The model A5100 atomic-absorption spectro- photometer incorporates automatic background correction using a deuterium hollow-cathode lamp, digital concentration read-out in direct and integrated modes and a gas safety system which shuts off the fuel automatically in the event of any failure. Baird-Atomic Ltd., Warner Drive, Spring- wood Industrial Estate, Rayne Road, Brain- tree, Essex, CM7 7YL.Spectrofluorimeter The SFRl 00 ratio recording spectrofluori- meter is now available. The instrument offers long-term stability within 1 yo and virtual excitation correction, giving research-type op- tical versatility. Baird-Atomic Ltd,, Warner Drive, Spring- wood Industrial Estate, Rayne Road, Brain- tree, Essex, CM7 7YL.Water-pressure Regulator A small, simple device designed to minimise problems arising from fluctuating water pressure and to effect economy of water usage is intro- duced. The regulator screws directly on to the tap and feeds the apparatus by a direct rubber or plastic pipe connection. Orme Scientific Ltd., P.O. Box 3, Stakehill Industrial Estate, Middleton, Manchester, M24 2RH.Vacuum Regulator A needle-valve regulator is available that bleeds air into a system, enabling accurate adjustment of vacuum systems to be made and maintained. Orme Scientific Ltd., P.O. Box 3, Stakehill Industrial Estate, Middleton, Manchester, M24 2RH. Disposable Filters An economically priced, disposable, compressed air and coalescing filter element is announced.The Bar 7 series has an efficiency of 99.99% and the element can operate with pressure differen- tials of up to 100 p.s.i. (7 bar). Balston Ltcl., Springfield Mill, Maidstone, Kent. Printer - Calculator for Digital Analysers Optilab have developed a 632 printer - calcula- tor to compute data direct from digital analysers with BCD output. A modification can be included to enable it to handle analogue outputs.Techmation Ltd., 58 Edgware Way, Edgware, Middx., HA8 8 JP. Automatic Dosing Apparatus The Fortuna semi-automatic dosing apparatus can be supplied with a number of variations, e.g., dosers of 0.2, 0-10, 0-30 and 0-50 ml (as well as threaded-necked flasks of different capacities, in amber glass or polyethylene, and screw-top test-tubes. The piston is PTFE coated and accuracies of f 0.5 yo are claimed.Anderman & Co. Ltd., Central Avenue, East Molesey, Surrey, KT8 OQZ. Membrane Filters The light-green colour and the black grid of 3.1 mm edge length considerably facilitate the identifica- tion and counting of small and light-coloured colonies in germ determination or other micro- biological investigations. The colour contrast remains homogeneously visible under the micro- scope even after autoclaving.Two pore sizes are available, 0.45 (BA 85/41) and 0.2 pm (BA 83/42). Anderman & Co. Ltd., Central Avenue, East Molesey, Surrey, KT8 OQZ.266 CORRESPONDENCE Proc. Analyt. Div. Chem. Soc. Aqueous SpectroStandards Chemplex Industries have available nearly 200 aqueous, single-element SpectroStandards for atomic-absorption, flame, X-ray and optical emission spectroscopy.Nine different base solutions are offered with individual element concentrations ranging from 100 p.p.m. to 1%. Chemplex Industries, Inc., 140 Marbledale Road, Eastchester, N.Y. 10707, USA. Ultramicrotome The LKB Ultrotome IV incorporates a new, accurate control of thickness in semi-thin sectioning for light microscopy, STEM and HVEM.LKB Instruments Ltd., LKB House, 232 Addington Road, South Croydon, Surrey, CR2 8YD. Literature An article on the applications of computerised dispersive infrared spectroscopy is available. The contents detail the means of solving pro- blems hitherto considered difficult or impossible by infrared spectroscopy. Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Bucks., HP9 1QA. A recent issue of the LKB Instrument Journal Science Tools [1977, 24(1)] includes articles on “Trends -in Amino Acid Sequencing,” “Deter- mination of Trypsin in Duodenal Fluid” and “Isolation of Plasmin Fab and Fc Fragments of Human IgG on Ultrogel AcA 44.” LKB Instruments Ltd., 232 Addington Road, South Croydon, Surrey, CR2 8YD. A new technical-service brochure illustrates the activities of the technical-service division of William Freeman of Barnsley, which has been established under the SUBA-TECH trade-mark. William Freeman and Co. Ltd., Suba-Seal Works, Staincross, Barnsley, Yorks., S75 6DH. Erba Science have made available a short-form catalogue of the Carlo Erba range of instrumen- tation. Erba Science (UK) Ltd., 14 Bath Road, Swindon, SNl4BA. The March 1977 issues of The AutoAnaZyst include articles on “Controlling Drug Quality” and “Monitoring Worker Health” in the Pharmaceutical edition and on “Total Haema- tology Automation’’ in the Clinical edition. Technicon Instruments Co. Ltd., Evans House, Hamilton Close, Basingstoke, Hants.

ISSN:0306-1396    

DOI:10.1039/AD9771400264

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

266 CORRESPONDENCE Proc. Analyt. Div. Chem. Soc. Correspondence Correspondence is accepted on all matters of interest to analytical chemists. Letters should be addressed to the Editor, Proceedings of the Analytical Division, The Chemical Society, Burlington House, London, W1 V OBN. Code of Practice for the Use of Gas Cylinders in Analytical Laboratories Sir, The introduction to the first of your series on Safety in Analytical Laboratories1 invites comments on the articles and on safety in general.The following comments are made on the “Code of Practice for the Use of Gas Cylinders in Analytical Laboratories.”l They relate specifically to three sections relevant to the use of liquefied flammable gases, and refer particularly to commercial propane and butane (to BS 4250). They would, however, also be relevant to other liquefied hydrocarbons in the the C, and C, range, and in most part to other liquefied gases.There is also one general comment. 1 . 2. Section 2.1.3 and Table I appear to use the phrases “flammability range” and “explosive limits” interchangeably and synonymously. Accepting that they are synonymous, we feel that the use of two phrases could lead to confusion.We recommend the use of the single phrase “flammable limits” in all cases, Section 2.3 could, we feel, also lead to confusion, and we recommend the following alternative wording. “For UK operations, cylinder filling ratios for liquefiable gases (BS 5355) are such that the cylinder will not become liquid full below 50 “C. If thisSeptember, 1977 THE ANALYTICAL CHEMISTRY TRUST 267 temperature is exceeded, dangerously high hydraulic pressure may develop.For this reason liquefied gas cylinders in storage or in use must not be placed immediately adjacent to radiators, steam pipes, ovens or other sources of heat.” 3. The fourth paragraph of Section 3.4.1 is fair comment provided the flame of burning gas is not transferring heat by direct impingement or by radiation to the cylinder.If this is happening the cylinder must be kept cool. We recommend the following as an alternative. “If flammable liquefied gas is escaping from a cylinder and burning so that the cylinder is heated by flame impingement or radiation, spray water on the cylinder to keep it cool. If, however, the flame is not heating the cylinder, do not spray water on it since this is likely to maintain or increase the rate of flow of the leak.” 4. We also feel as a general point that the Code should refer positively to information obtainable from manufacturers/suppliers of gases in cylinders.This would, for exam- ple , be relevant to cylinder identification, which, as the Code mentions, is not com- pletely unambiguous so far as codes and standards are concerned.We suggest the following wording. “The information in this Code should be supplemented by pro- duct data sheets and other information relevant to the safe storage, handling and use of gases in cylinders obtained from the manufacturer/supplier. ” We hope that these suggestions will be useful in the preparation of any revised version of what is basically an excellent and useful document. Reference 1. Proc. Analyt. Div. Chem. SOL, 1977, 14, 57. Yours faithfully, C. A. Miller Secretary, Liquefied Petroleum. Gas Industry Teclanical Association (UK), P.O. Box 5, Shepperton, Maddlesex, T W 17 9A A

ISSN:0306-1396    

DOI:10.1039/AD9771400266

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

September, 1977 THE ANALYTICAL CHEMISTRY TRUST 267 The Analytical Chemistry When the Society for Analytical Chemistry agreed to participate in a three-year trial amalgamation period with The Chemical Society its Council resolved to create a Trust Fund comprising the financial assets of the Society. The Trust was constituted by a Trust Deed dated February 9th, 1972. The resolution approving full amalgamation with The Chemical Society was subsequently passed at an Extra- ordinary General Meeting of the SAC on October 23rd, 1974.One clause of the Amal- gamation Agreement provided for transfer of the surplus assets of the SAC to The Chemical Society and to implement this the initial Trust was dissolved and a new one, having identical objects and entitled The Chemical Society Analytical Chemistry Trust, was created by a Trust Deed dated December 12th, 1974.Apart from annual subventions by The Chemi- cal Society to the Analytical Division in respect of its membership subscriptions and subscrip- tions to the Division’s Subject Groups the Analytical Chemistry Trust Fund represents the entire financial resources of the Analytical Divi- sion ; its Trustees are the Honorary Officers and elected Council members of the Division.The monies are held on investment and the interest Trust earned is used to fund the objects of the Trust. Clause 5 of the Trust Deed sets out the objects as follows. “Subject as aforesaid the Trustees may apply the capital and income of the Trust Fund for all or any of the purposes of this Deed in such manner as the Trustees shall think fit and in particular (but without restricting the generality of the foregoing provisions of this Clause) - (a) in providing or in assisting in providing means (including books, instruments, plant equipment, chemical and other materials) for the pursuit of research and investigation into all matters relating to the development of Analytical Chemistry; (b) in organising lecture tours and conferences in Analytical Chemistry and in awarding medals and prizes to outstanding workers in Analytical Chemistry ; (c) in supporting close co-operation with Analytical Chemists of other countries by organising meetings and exchange visits ; (cl) in encouraging improvements and develop- ments in methods and techniques for the publication and dissemination of informa- tion in Analytical Chemistry ; ( e ) in developing, organising, entering into and268 THE ANALYTICAL CHEMISTRY TRUST PYOC.Analyt. Div. Chem. SOC. The Chemical Society Analytical Chemistry Trust Fund Income and Expenditure Account For the period from October lst, 1975 to September 30th, 1976 Surplus Arising from Journal Publications and Book Sales .... .. Interest on Loan and Deposit Accounts . , . . .. .. .. . . Income from Ties, Badges and Shields .. .. .. .. .. .. Income from Investments . . .. .. .. .. .. .. .. TOTAL INCOME . . .. .. .. .. .. .. .. .. .. Less ; EXPENDITURE Contribution to Expenses of CS Analytical Division .. .. . . .. Studentships, Grants and Prizes . . .. .. .. .. .. .. Gold and Silver Medals .. .. .. . . .. . . .. .. .. Audit and Professional Fees . . .. .. .. . . .. .. .. Printing Costs . . .. . . .. .. .. . . .. .. .. Postage, Travelling and Sundry Expenses . . .. .. . . . . .. College of Arms: Crest . . .. . . . . .. .. .. .. .. Donation to Analytical Methods Committee . . . . . . .. . . .. EXCESS OF INCOME OVER EXPENDITURE CARRIED TO BALANCE SHEET . . .. Balance Sheet as at September 30th, 1976 INVESTMENTS AT COST Balance as a t October lst, 1975 .... .. .. .. .. .. Add: Investments Purchased during the year . . .. .. .. .. Less : Cost of Investments disposed of .. .. .. .. .. . . CURRENT ASSETS Deposit Accounts with Banks .. .. .. .. .. .. . . Investment Deposit Account . . .. .. .. . . .. .. .. Income Tax Recoverable . . .. .. .. . . .... .. Cash a t Bank . . .. . . . . .. .. .. . . .. .. Sundry Debtors . . .. . . .. .. .. .. .. .. .. Less : CURRENT LIABILITIES Sundry Creditors . . . . .. .. .. . . . . .. L 54 572 17 118 16 712 21 j5 88 423 5 372 5 873 282 668 5 707 1011 1170 1500 21 583 A66 840 305 593 297 013 602 606 161 798 440 808 30 679 56 600 8 274 1346 47 246 144 145 5 365 REPRESENTED BY TRUST CAPITAL ACCOUNT Balance as a t October lst, 1975 .... a . .. .. .. .. 300 800 Add: Transfer from SAC .. .. .. .. .. .. .. .. 178 000 478 800 Less: Loss on Sale of Investments . . .. .. .. .. .. .. 7 558 138 780 A579 588 471 242 INCOME AND EXPENDITURE ACCOUNT Balance as a t October lst, 1975 .. .. .. .. .. . . .. 41 507 Add: Excess of Income over Expenditure for the year . . * . .. . . 66 839 108 346 l579 588September, 1977 REPORT ON THE SECOND carrying out or co-operating in any charitable project or projects which is or are calculated to further the purpose of this Deed ; (f) (i) in establishing and maintaining a fellowship or fellowships to be called “The Society for Analytical Chemistry Fellow- ships” of such value as the Trustees may from time to time determine such fellow- ships to be awarded to such persons and to be held and enjoyed as hereinafter pro- vided ; (ii) in establishing and maintaining a studentship or studentships to be called “The Society for Analytical Chemistry Studentships” of such value as the Trustees may from time to time determine such studentships to be awarded to such persons and to be held and enjoyed as hereinafter provided ; (iii) any such fellowships or studentships as aforesaid shall be awarded at such intervals and in such conditions and to such persons and shall be held and enjoyed for such periods upon such terms and condi- tions as shall from time to time be deter- mined by regulations to be made by the Trustees. The Trustees may at any time revoke or alter any regulations made under the provisions of this section of this sub- clause and make new regulations in the place thereof .” The interest accruing from the invested capital of the Trust Fund is used to support the foregoing objects in several ways.It contri- butes to the operating costs of the Analytical Division in its broadest sense. The Division has continued to sponsor, both centrally and through the Groups and Regions, a broad spectrum of scientific meetings at a frequency similar to that obtaining before amalgamation and the SAC policy of keeping registration fees to a minimum has been maintained.The costs incurred, together with the central administra- tive costs, exceed The Chemical Society grant to the Division. The shortfall, currently about f17 000 per annum, is met from the interest.More specifically, the Trust is responsible for expenses related to the several Divisional Awards, the SAC Gold and Silver Medals, the Distinguished Service Award and the Theo- philus Redwood Lecture. In addition, the Trust has made available grants to enable bona fide students to attend major conferences run by the Division and, formerly, the Society.L250 was provided for this purpose for the SAC Centenary Conference in 1974 and k500 has been similarly set aside for SAC 1977. JOINT ACS/CIC CONFERENCE 269 In 1973 the Trustees of the SAC Analytical Chemistry Trust instituted the SAC Fellowship and Studentship awards, which are advertised annually each autumn. To date no suitable proposals for the award of a Fellowship have been received but four Studentships have been awarded as follows: Professor T. S. West (Imperial College, London) ; Dr. A. Townshend (University of Birmingham) ; Dr. D. Betteridge (University College, Swansea) and Mr. G. E. Penketh (ICI Wilton) ; and Dr. G. F. Kirkbright (Imperial College, London). The audited statement of accounts for the period October lst, 1975 to September 30th, 1976 is given on the opposite page.

ISSN:0306-1396    

DOI:10.1039/AD9771400267

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

September, 1977 REPORT ON THE SECOND JOINT ACS/CIC CONFERENCE 269 Report on the Second Joint ACS/ClC Conference This Conference, organised jointly by the American Chemical Society and the Chemical Institute of Canada, was held in Montreal, May 29th-June 2nd, 1977. The Conference was well attended, with participants from both sides of the border. Although the sessions of the Analytical Chemistry Division of the CIC were not joint with its ACS counterpart, many papers in these sessions were presented by participants from the US.The first session of the Analytical Division (Symposium on Environmental Analysis) proved to be the most contentious, especially in regard to the high levels of toxic heavy metals in the environment, as reported by Dr. Gubeli (Lava1 University). His values were challenged by subsequent speakers who indicated that contamination of the samples could account for these relatively high values.Dr. Shier Berman (NRC, Ottawa) provided a fitting denouement to the first session when on Tuesday afternoon (Symposium on Trace Analysis) he discussed the problems of doing trace analysis free of contamination. In the discussions that followed both Dr.Berman’s address and Dr. Corsini’s (McMaster University) address (en- titled “New Horizons in the Design and Use of Selective Reagents”) there seemed to be a general consensus that selective pre-concentra- tion of analytes was perhaps the most pressing problem in the area of trace analysis. The Fisher Scientific Award Lecture delivered by Dr. J. L. Monkman (formerly of Environ-270 NEW PHARMACOPOEIA COMMISSION CHAIRMAN Proc.Analyt. Div. Chem. SOC. ment Canada) was a humorous examination and metals based on the Landolt Reaction, imrnobil- evaluation of the instrumentation and tech- ised ligands on glass and on polyurethane, niques used in environmental analysis and the micellar systems in analytical chemistry, metal- results obtained therefrom. specific detectors in atomic-fluorescence spectro- Several novel approaches and methods were scopy and the application of X-ray photo- described at the various sessions. Ion chrom- electron spectroscopy in the evaluation of art atography, catalytic - kinetic determination of objects represented only a few of the highlights.

ISSN:0306-1396    

DOI:10.1039/AD9771400269

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

270 NEW PHARMACOPOEIA COMMISSION CHAIRMAN Proc. AnaZyt. Div. Chem. SOC. Meetings and Courses Applications of Tuneable Lasers September 28, 1977, London The Spectroscopy Group and’ the Quantum Electronics Group of The Institute of Physics are organising a 1-day meeting on the applications of broad-band tuneable lasers, to be held at the Department of Physics, Queen Mary College, Mile End Road, London, E.1.The meeting will cover (a), recent develop- ments in CW and pulsed broad-band tuneable lasers from the infrared to the ultraviolet region and ( b ) , applications of tuneable lasers in experiments on such topics as parity violation, coherent spectroscopy, atomic collision cross- sections and resonant Raman scattering. An exhibition of commercially available tuneable lasers will be held in conjunction with the meeting.Further details and application forms can be obtained from The Meetings Officer, The Institute of Physics, 47 Belgrave Square, London, SWlX SQX. Orion Workshops on Ion- selective Electrodes October, 1977 A further series of workshops will be held as follows : Oct. 10, Bristol Oct. 11, London Oct. 12, London Oct. 13, London Oct.24, Glasgow Oct. 25, Edinburgh Oct. 26, Newcastle Oct. 27, Leeds Oct. 14, Leicester For details, write to Orion Workshops, Mrs. D. Barton, MSE Scientific Instruments, Manor Royal, Crawley, West Sussex, RHlO 2QQ. Oct. 28, Manchester Applied Research Laboratories Analytical Symposium November 1-2, 1977, York Papers to be presented at this Symposium include the following : “ARL’s Latest Develop- ments” ; “Sampling and Preparation Tech- niques (a), Low-carbon Steel (b), Copper Base (c) , Cast Iron (d), Aluminium”; “Scanning Electron Microprobes (Applied to Non-ferrous Materials)” ; “Introduction to New Laboratory Automated Systems.” Applied Research Laboratories Ltd., Wingate Road, Luton, Beds.Intervational Symposium on Applications of Electroanalytical Sensors December 6-8, 1977, Londorz A 3-day Symposium- on the applications of electroanalytical sensors for process measure- ment and control, and for industrial and clinical analysis, will take place at The City University, London.The Symposium is being organised by Sira Institute, and follows the June 1975 group ofSeptember, 1977 PUBLICATIONS RECEIVED Sira seminars on the applications of ion- selective electrodes and related electrochemical sensors.The new programme concentrates on further developments in the application of pH and ion-selective electrodes, ion-selective fet’s and other electrochemical sensors, and includes other work not covered in the 1975 programme. Authors of papers are expected to include: Dr. I). Ammann and Professor W, Simon (Swiss Federal Institute of Technology) ; Ilr.D. M. Band (St. Thomas’s Medical School, UK) ; Dr. B. J. Birch (Unilever Research, UK) ; A. E. Bottom and D. E. Collis (Electronic Instruments Ltd., UK); Dr. A. K. Covington (University of Newcastle-upon-Tyne, UK) ; Dr. A. S. Hallsworth (University of Leeds, UK); Dr. G. Kassebeer (Bran & Lubbe, West Germany) ; Professor J . I).Kruse- Jarres (Uni- versity of Freiburg, West Germany); G. Kots (Philips Research Laboratories, Eindhoven, The Netherlands); Miss E. E. MacFadyen, Dr. C. Main and P. Newman (University of Glasgow, UK) ; Dr. G. J . Moody and Dr. J . D. R. Thomas (University of Wales Institute of Science and Technology, UK) ; F. Oehme (Polymetron, Switzerland) ; R. J. Simpson (Sira Institute Ltd., UK); and Dr.E.C. Weller (Kodak Ltd., UK). A small, selective exhibition of available electroanalytical sensors and their uses will be associated with the Symposium. Further information can be obtained from Mrs. R. G. Keiller, Sira Institute Ltd., South Hill, Chislehurst, Kent, BR7 5EH. 27 1 Ion Sputtering and Depth Profiling in Surface Analysis Decewber 14, 1977, London The Thin Films and Surfaces Group of The Institute of Physics is arranging a 1-day meeting on the above topic a t Imperial College.The meeting will concentrate on the understand- ing and characterisation of problems associated with the combination of surface analytical tech- niques and ion sputtering to study surface and sub-surface compositions in a range of surface and thin-film applications. Both invited and short (about 20 min) contributed papers will be included and offers of contributions should be directed to Dr. D. P. Woodruff, Department of Physics, University of Warwick, Coventry, CV4 7AL. Further details and registration information will be available in October from The Meetings Officer, The Institute of Physics, 47 Belgrave Square, London, SW1X SQX.

ISSN:0306-1396    

DOI:10.1039/AD977140270b

出版商:RSC    

年代:1977

数据来源: RSC