摘要:

Proceedings of the Society for Analytical Chemistry Analytical Division Chemical Society CONTENTS Retirement of Mrs. H. I Fisk . . 227 The Midlands Region . . . 228 The Use of Enzymes in Auto- matic Analysis. . . . . . 230 Summaries of Papers "Newer Physical Methods of An- alysis in Clinical Chemistry" . . 236 "Standardisation of Methods and Materials" . . . . 238 The Chemical Society's Library 240 Papers Accepted for The Analyst 240 Publications Received . . . 241 Erratum . . . . . . . . 242 Forthcoming Meetings Back Cover Proc. SOC. Analyt. Chem. Vol. 10 No. 9 Pages 227-242 September 1973 PAYCAL Vol. 10 No. 9 September 1973 PROCEEDINGS THE SOCIETY FOR ANALYTICAL CHEMISTRY ANALYTICAL DIVISION CHEMICAL SOCIETY OF Hon. Secretary W. H. C. Shaw Officers o f The Society for Analytical Chemistry and the Analytical Division of The Chemical Society President G.W. C. Milner Hon. Treasurer Hon. Assistant Secretaries J. K. Foreman D. I. Coomber O.B.E. D. W. Wilson Secretary Miss P. E. Hutchinson 9/10 SAVILE ROW LONDON WIX 1AF Telephone 01 -734 9864 Managing Editor SAC Publications F. D. Grimmer Assistant Editor P. C. Weston Proceedings is published by The Society for Analytical Chemistry. Members' subscriptions must be sent t o The Chemical Society Nonmembers can be supplied with Proceedings only as part of a combined subscription with The Analyst and Analytical Abstracts Single copies can be obtained direct from The Chemical Society Publications Sales Office Blackhorse Road Letchworth Herts. SG6 1 HN (NOT through Trade Agents) price 30p post free. Remittances MUST accompany orders 0 The Society for Analytical Chemistry I ANALYTICAL SCIENCES MONOGRAPH No. 1 H i g h - Precision Tit ri met ry by C. Woodward and H. N. Redman Imperial Chemical Industries Limited (Agricultural Division) BRIEF CONTENTS Introduction Visual Titrations with sections on Apparatus Standard Substances and their preparation and Instrumental Methods with sections on Photometric Titrations Electrometric Titrations and assay and Standard Solutions. Miscellaneous Techniques. References to the literature of high-precision titrimetry. Price f2.50 Pp. viii+63 ISBN 0 85990 501 2 Society for Analytical Chemistry Book Department 9/10 Savile Row London W1 X 1 AF Members may b u y personal copies at t h e special price of €2.00

ISSN:0037-9697    

DOI:10.1039/SA97310FX030

出版商:RSC    

年代:1973

数据来源: RSC

摘要:

SOCIETY FOR ANALYTICAL CHEMISTRY ANALYTICAL DIVISIOK CHEMICAL SOCIETY Forthcoming Meetings-contimted j r o m back covey October- continued Wednesday 17th MIDLANDS REGION joiiztl>i with the UV Group on “UV and Visible Spectro- NOTTINGHAM photometry of Difficult Samples.” “Solid Scattering Samples,” by 4 . J . Everett. “UV Spectra of Scattering Low Temperature Matrices,” by Professor J. J . “Microcell Techniques and Related Problems ” by K. \V. Smalldon. “Fugitive/Photoreactive Samples,” by A. L. Glenn. “Extent of Reaction and Automation,” by J . \V. Murfin. “Adsorption on to Cell Walls,” by D. Thorburn Burns. Lecture Theatre The Boots Co. Ltd. Pennyfoot Street Xottingham; 2 p.m. ELECTROAKALYTICAL GROUP jointly mith the Society of Chemical Industry on “Liquid - Liquid Extraction and Ion-exchange in Analytical Chemistry.” “Current Uses of Liquid - Liquid Extraction in Analytical Chemistry,” by Pro- fessor H.M. AT H. Irving. “Methods for Identification of Organic Phase Species,” by A. G. Xaddock. “Influence of Interfering Ions on the Performance of Liquid Ion-exchange “Trapped Liquid Membranes-Mainly in PVC-for Ion Selective Electrodes,” Society of Chemical Industry 14 Belgrave Square London S.LY.1; 11 a.m. Wednesday 24th NORTH WEST REGIOX jointly with the North Lancashire Section of the CS. “Recent Advances in Forensic Analysis,” by F. L. Cann. Preston; 7.30 p.m. Turner. Monday 22nd 1,ONDON Membrane Electrodes,” by B. Fleet. by J . D. R. Thomas. PRESTOS SOCIETY FOK ANALYTICAL CHEMISTRY AKALYTICAL DIVISION CHEMICAL SOCIETS Forthcoming Meetings September Thursday 20th GLASGOTV SCOTTISH REGIOX jointly with the Scottish Region of the Industrial IXvision of the CS on “The Importance of the Analyst to Management (with Special Reference to Changes Due to UK Entry into the EEC).” Speakers to include C.Whalley J . K. Foreman and D. K. Deans. University of Strathclyde Glasgow; 10 a.m. Thursday 20th MICROCHEMICAL METHODS -ATOMIC SPECTROSCOPY XUTO~IXTIC ~ ~ T H O D S RADIOCHEMICAL METHODS ELECTROANALYTICAL and EDECATIOS AND TRAIS- ISG GROUPS and the SOKTH \VEST REGION on “Trace Analysis-Different Speakers L. S. Bark H. J . R.I. Bowen R. -4. Chalmers J . €3. Clegg G. C,. l>ickson F. T. Eivart J . H. S. Green I. Fraser J . Hislop R. D. jee G. F. Kirkbright K. \V. Metcalf D. M. Poole A. Townshend C . J . Little R. J . McCulloch J . R1. Ottaway T.B. Pierce D. B. Roodyn and J . IT’arren. and Friday 21st SALFORD Approaches.” The University Salford. Monday 24th to CS Autumn Meeting. Symposium organised by SAC.’AD on “The Charac- Thursday 27th terisation of Materials.” XORWICH Cniversity of East Anglia Sorwich. October Tuesday %nd SHEFFIELD ATOMIC SPECTROSCOPY GROUP jointly wzth the Sheffield Netallurgical Society on “State of the Art-X-rav Fluorescence and Emission Spectroscopy for Capper and Steel.” B.I.S.R.X. Hoyle Street Sheffield; 7 p.m. IVednesiiay 3rd SACiAD meeting on “Titrinietric Analysis.” “Radiofrequency Titrations- LONDOX Their Present and Future,” by G. Svehla. “Thermometric Titrations,” by L. S. Bark. “High Precision Titrimetry,” by J . M. Skinner. Scientific Societies Lecture Theatre 2 3 Savile Row London JV.1 ; 3 p.m. NORTH EAST REGIOS Social evening and Dinner. “Leisure Laughter and Lunatics,” by G. G. Watson. Scotch Corner Hotel near Richmond Yorks; 7 p.m. Tuesday 9th RICHMOKD IVednesday 10th EAST ANGLIX REGIOX Annual General Meeting followed bv an Ordinary HATFIELD Meeting.. Thursday 11th CARDIFF Thursday 1 l t h LOKDOK “Inspection and Sampling Under the Medicines Act,” by A. G. Fishburn. Hatfield Polytechnic College Lane Hatfield Herts; 3 p.m. ~VESTERK KEGIOK joinlly with the South East Wales Section of the CS. “Catalytic Methods of Trace Analysis,” by J . 31. Ottaway. University of Wales Institute of Science and Technology Cardiff; 5.30 p.m. BIOLOGICAL METHODS GROUP on “Microbial Attributes of Yon-sterile l’harma- Speakers H. S. Bean D. F. Spooner and X . J . Iran AbbC. Pharmaceutical Society 17 Rloomsbury Square London 1T.C. 1 ; 2.30 p.m. ceuticals and Cosmetics.” [cenizq2iud iizszde back couey Printed by Heffers Printers Ltd Cambridge England

ISSN:0037-9697    

DOI:10.1039/SA97310BX032

出版商:RSC    

年代:1973

数据来源: RSC

摘要:

September 1973 PROCEEDINGS OF Vol. 10 No. 9 THE SOCIETY FOR ANALYTICAL CHEMISTRY ANALYTICAL DIVISION CHEMICAL SOCIETY Retirement of Mrs. H. I. Fisk MRS. H. I. FISK Editor of Analytical Abstracts has retired from the staff of SAC. She had been associated with the journal for all but its first year of publication. Mrs. Fisk joined Analytical Abstracts as Assistant Editor in 1955 having previously been on the editorial staff of the Society of Chemical Industry. In 1963 she was appointed Editor on the retirement of Dr. N. Evers who had held the post since the start of the journal in 1954. The period of Mrs. Fisk’s editorship has been one of considerable change and growth of Analytical Abstracts. There has been the constant need to extend the coverage of the journal as the scope of analysis has broadened and as new techniques and new journals have appeared.The nature of the abstracts themselves has changed in part in that the proliferation of papers on instrumental techniques has necessitated some departure from the earlier aim to produce “working abstracts.” New systems of nomenclature and units have had to be accommodated. Certain changes in the journal including a rearrangement of the division into subject topics were instituted as a result of information gained from a questionnaire sent to subscribers in 1967. Above all there has been the problem of keeping pace with the ever-growing volume of analytical literature published and the task of seeking to minimise the time-lag between the publication of a paper and publication of the corresponding abstract in Analytical Abstracts.The growth of the journal under Mrs. Fisk’s editorship is illustrated by the 9853 abstracts published in 1972 as compared with 5564 in 1962. This increase in size led to the decision to publish the journal in two volumes per year in 1969. And although the time-lag had tended to increase as the number of abstracts published rose a determined onslaught on this problem 227 228 THE MIDLrlNDS REGION [PYOC. SOC. ilnalyt. Chena. in recent years has cut the time-lag to about 7 months a notable achievement as this period is about the minimum possible with the present method of production of the journal. The success of an abstracts journal depends not only on the number of abstracts and their speed of publication but also on the quality of the abstracts and there is always the temptation to sacrifice the latter in pursuit of the former.Mrs Fisk with the support of the Abstracts Editorial Committee has always sought to maintain and improve the quality of abstracts despite the constant call to publish more abstracts and the many other pressures. I t should also be recognised that the preparation of abstracts is a very specialised art with no sizeable pool of trained labour on which an abstracts journal can draw. ?Jot the least of Rlrs. Fisk’s achievements has been to train and weld the staff of Aizalytical Abstracts into the present most effective team a team which should continue to give good service to the journal and thus to the Society in years to come. Mrs. Fisk has never been a “non-playing captain”; in many of the editorial tasks she has been a member of the team as well as its leader and in this way has encouraged the editorial staff to emulate her own high standards. But the value of Mrs. Fisk’s editorship cannot be assessed by statistics alone. The Society wishes Mrs Fisk and her husband a long and happy retirement. H. J. CLULEY

ISSN:0037-9697    

DOI:10.1039/SA9731000227

出版商:RSC    

年代:1973

数据来源: RSC

摘要:

228 THE MIDLrlNDS REGION [PYOC. SOC. ilnalyt. Chena. The Midlands Region THE Midlands Region of the SAC was inaugurated in 1955 but to understand its development it is necessary to start some 6 years earlier. Scanning pre-war copies of The Analyst leads tc the surprising conclusion that virtually no meetings were held in the Midlands area. The catalyst for the formation of an active analytical group was the arrival of Konald Belcher in Birmingham from Aberdeen and his discussions with notable analysts in the area such as Mr I;. C. J. Poulton (Dunlop Rubber Co. Ltd.) and Dr. H. C. Smith (Coventry Technical College). In 1980 the Midlands Analytical Methods Discussion Group was formed the first Chairman being hIr. J. R. Leech with MS. FV. h1. Lewis as Honorary Secretary. The first meetings were held in the old Crown Hotel in Birmingham thus setting a tone of conviviality which has been maintained through the years; but later most of the lectures were given in the old Mason College of the University in the city centre-now long demolished.The membership at that time was about 120 and rarely did less than 50 per cent. turn out for meetings. The records of these meetings can be found in Chemical Age with Drs. -4. J. Xutten and IY. I. Stephen as Recorders. In 1952 the Group changed its name t o the Midlands Society for Analytical Chemistry. The first notable event was a 2-day Symposium which was attended by several well known foreign analytical chemists. Unhappily this symposium-inter din-led to some disagree- ment between the (then) Society of Public Analysts and the Midlands Society because it followd immediately after an IUPAC Conference organised by the Society of Public Analysts in Oxford.Still an independent body the llidlands Society organised a large International Symposium in 1984 and this highly successful meeting started the Birmingham symposium traditions of attracting many notable foreign visitors and of having as lavish hospitality as could possibly be afforded. It was a t this time that Honorary Membership was given to Professors F. Burriel-Uarti (Spain) C. Duval (France) F. Feigl (Brazil) J. Gillis (Belgium) and H. Nalissa (Austria) Drs. R. L. Mitchell (Scotland) and J. Unterzaucher (Germany) and Professor P. W. West (U.S.A.). When in 1955 the Society of Public Analysts and Other Analytical Chemists became the Society for Analytical Chemistry moves to secure a rapprochement between the SAC and the AIidlands Societies were led by Dr.D. W. Kent-Jones then President of the SAC and Dr. R. Belcher. The Midlands Society became the hIidlands Section of the SAC in the Spring of 1955; this move had the great advantage of enlarging the Xdlands Section to include Xottingham thus bringing in a very valuable influx of active members from Boots Ltd. ; but it had the unfortunate consequence that enthusiastic younger people found that they could no longer afford Society dues and some lost interest in attending meetings. This latter situation has never really been retrieved despite the later introduction of student September 19731 THE MIDLANDS REGION 229 membership of the Society. The fact that the Midlands had its own Society before becoming the Midlands Section engendered a certain feeling of healthy provincial independence.After the amalgamation the first Chairman of the Section Mr. J. R. Leech and his committee organised the normal Society meetings and lectures and ever since the Section has held about ten meetings each year not only in Birmingham and Nottingham but in other centres such as Stoke-on-Trent Coventry Hereford Loughborough Ipswich and Luton. Since the region extended from Stoke-on-Trent to Colchester and from Brecon to Boston containing many large industrial centres it has been no small problem to provide adequate coverage. The 1954 Symposium left the Section in a sound financial position which allowed the Section the privilege of inviting some well known foreign chemists to take part in the annual programme-a feature which has continued to the present time.Another Symposium was held in 1958; again this was very successful scientifically socially and financially with a large contingent of foreign visitors. At this meeting Professor Fritz Feigl gave a famous lecture on spot tests which was so well received that it had to be repeated the following day to a second overflow audience-an occasion which appears to be unique in the history of analytical symposia. Professor Professor Feigl’s long relationship with the Midlands culminated in the Section’s holding a symposium in honour of his 70th birthday in 1962. This meeting followed the pattern of previous symposia in Birmingham with widespread support from many industrial firms and exhibitors facilitating the provision of the traditional hospitality.The tremendous services given by Mr. J. R. Leech as Chairman and Mr. I;. C. J. Poulton as Symposium and Section Treasurer (1955 to 1964) to the organisa- tion of these meetings must be recorded; the burden of the Secretary’s position passed from Dr. J. W. Robinson to Dr. (then Mr.) W. T. Elwell to Mr. M. L. Richardson for the three meetings. In 1965 and 1968 the parent Society held its triennial Conferences in Nottingham under the Presidencies of Dr. D. C. Garratt and Dr. A. A. Smales respectively. These meetings were also very popular and well attended. The collaboration of members of the Royal Institute of Chemistry and of the Society for Chemical Industry in the organisation of these meetings in Birmingham and Nottingham must be mentioned; thiq help was greatly valued for the large-scale effort involved tends to be too much for a single Society committee.LEFT-~WY. S . Gveeitfield (Chairman) RIGHT-DY. D . Thovburn Uuvns (Vice- Chairman) The most recent Midlands Symposium was held in honour of Ronald Belcher in 1969 and this firmly established Birmingham’s reputation for interesting and convivial conferences ; the attendance was just under 700 and again very many people came from all over the world for the meeting. On this occasion Dr. W. T. Elwell was Chairman Mr. Poulton continued his unexcelled service as Treasurer and Mr. D. M. Peake was Secretary. The various Symposia and Conferences provide the highlights of the history of what has now become the Midlands Region but of course the normal business of lecture meetings committee decisions and occasional social meetings has run continuously.The Region has provided many valuable members of the Council of the Society and members of the Midlands committee who later became Presidents of the Society are Professor T. S. West and Mr. C. Whalley ; members who have been Vice-presidents of the Society include Professor R. Belcher Dr. W. T. Elwell Mr. C. A. Johnson and Mr. F. C. J. Poulton. 230 THE MIDLASDS REGION [ P V O C . SOC. AItnl>t. Chcnt. A feature of the annual programmes is the presentation of the Elwell Award an embossed silver cigarette box and a monetary prize for the best original paper offered bv any meniber of the Region under 30 years of age. The region is perhaps reniarkable for its friendliness and sociability its excellent collaboration between analytical chemists from the industrial arid acadeniic fields its lack of personal rivalries within the region and its staunch resistance to outside interference.Undoubtedly these features are due to the outstanding personalities of the people who have guided the development of analytical chemistry in the region. There are too many to list conipletely but special mention must be made of the services given over the years 11y Pro- fessor K. Belcher (the late) JIr. J. R. Leech Dr. S. H. Jenkins Mr. w. >I. Lewis Mr. G. \V. Cherry (the late) Dr. H. C. Smith hIr. H. J. (;. Cliallis Dr. \ir. T. Elwell Mr. F. C. J. Poulton JIr. 31. L. Richardson JIr. S. Greenfield Mr. L). 11. Peake 11r. I<. Hyde and finally (but definitely not lcast for he is a mainstay of the Kegion) JIr.H. E. Brookes. For the future the Committee o f tlic JIidlaiids Region hopes tliat collaboration with other Groups and Divisions will flourish within the new structure o f the Cheniical Society and that this new organisation will he sufficiently dynaniic and forward looking to re\-ive the waning interest of young rnenil~er..; of the profession so that they can enjoy the undoubted benefits of mi-ticirntion in tlie activities of the Region that l m x ~ lieen of such great \ ~ l u e I I to the more establislwd members. r. 1 lie Cliairinan and Secrctarics ( ,I. R . Lwcli (1956-57) R. 13elcher (lO:‘,7-m) S. H. Jenkins (1959-6 H. C. Sniitli (1961-63) Chairnian f the Kcgion ha\.e liccii as follows- Secretary G. \Ir. Cherry (1955-63) IfT. H. Stephenson (1963-65) M. 13. Hrookes (1967-69) IY. 11. Lewis (1969-70) P. G. 11‘. Cobb (1970-72) 11. L. Ricliardson (1963-67) S. Greenfield (1967-70) D. 11. Peake (1070-72) IT. T. ISl\~ell (1965-67) S. Greenfield (1972- ) A. G. Fogg (1972- )

ISSN:0037-9697    

DOI:10.1039/SA9731000228

出版商:RSC    

年代:1973

数据来源: RSC

摘要:

230 THE MIDLASDS REGION The Use of Enzymes in Automatic Analysis* ENZYMES are being used to an ever-increasing extent in automated assays in analytical chemistry and biochemistry. Rather than trying to cover such a large topic in detail this paper deals with some of the basic procedures that are involved in automated enzyme analysis * Olving to unforcsecn circumstances the author was unable to present this paper a t a Joint Meeting of the North \Vest Region and Automatic Methods and Electroanalytical Groups on “The Use of Enzymes in Xnalysis” held at the ‘ITniversity of Salford on June 37th 1973. September 19731 THE USE OF Eh‘ZYMES I N AUTOMATIC ANALYSIS 231 and indicates the variety of approaches that are now possible (see Roodynl and Jowett? for further details). Most of the paper concerns the determination of enzyme activity Z’.e.the amount of sub- strate broken down per unit time by a given enzyme sample. In many biological investiga- tions it is this value that is required e.g. the level of blood transaminases the cytochrome oxidase activity of a mitochondria1 preparation and the cholinesterase activity of a preparation of nerve tissue. However enzymes are also used to an ever-increasing extent to measure the concentration of specific substances for example the determination of glucose by glucose oxi- dase lactate by lactate dehydrogenase and NXDP or glucose-6-phosphate by glucose-6- phosphate dehydrogenase. In such assays the enzyme is used essentially as a highly specific reagent The calculation of enzyme activity requires a knowledge of the effectiL7e incubation time and the relationship between the instrument reading and amount of substrate trans- formed.The use of enzymes as assay reagents requires a knowledge only of the second re- lationship and in general requires less instrument calibration and computation provided that the assa>- can be calibrated with standard graphs. However in other respects the two types of analysis are very similar and identical problems can arise in sampling preparation of the reaction mixture instrument settings and the processing of the output by the recording in- struments. The more general problem of the automation of the determination of enzyme activity is therefore discussed and the use of enzymes as reagents should be regarded as a special case of the use of such systems. The appropriate reagents must be prepared either by direct weighing or by dilution of suitable stock reagents.The correct (calculated) volumes of the reagents are mixed in the correct sequence so as to produce the reaction mixture which is transferred to a suitable incubation vessel and the reaction started by the addition of enzyme or substrate. The progress of the reaction is followed by a suitable measuring device or sensor (which is very often a spectrophotometer) and the output of the sensor is put on to a suitable record which is usually the chart of a pen recorder. The record is then transformed by a suitable calculation into the value finally required. For an assay of enz>me activity this value is preferably micromoles of substrate transformed per minute or micromoles of product per minute.If the enzyme is used as a reagent the result is calculated simply as micromoles of substrate or product per unit volume of sample taken. The results may well require further processing such as corrections for sample dilution calculation of specific enzyme activities (micromoles per minute per milligram of protein). As a result of all these processes the conditions for the next assay or set of assays is decided upon and the pro- cess repeated (see Table I ) . \Yhen one considers the extent to which the above processes have been automated or a t least are amenable to automation it is immediately clear that current technology can provide immense capability in every part of the system (see Table 11). The extent to which a given system can be automated is now virtually a function of the funds available and little else.Hence the eventual development of the “totally automated system” in which all of the above processes including necessary adaptations to the assay procedure in the light of the flow of results are carried out under on-line computer control seems inevitable. In such a system the opqratorjs) would only have to supply the required solid or liquid stock reagents check the maintenance of the moving parts specify the assay or group of assays required supply the samples and of course collect the results. The likelihood that such systems will become avail- able to an ever-increasing extent is best shown by considering the various stages in Table I1 separate1 . The preparation of standard reagents can be automated by the use of automatic balances autopipettes variable-speed single or multichannel pumps autodiluters mixers etc.The calculations for the preparation and dilution of reagents are readily carried out on a computer. In our laboratory the section of the FORTRAN program involved in these calculations also prints out detailed weighing sheets for a given set of reagents (see Table 5 in Ref 3 for example). In ciur system the final dilution of the various reagents depends on previous instrument cali- brations that measure the precise flow-rates in the various pump lines of the AutoXnalyzer. The computer calculates the relative flow-rates (fractional line volumes) and hence the dilution of stock reagent necessary to give the required final concentrations of reagents in the reaction mixture (some typical output is shown in Table 4 in Ref.3). \Ye have used batch process- -111 enzyme assay involves the following processes. 232 THE USE OF EXZY~IES IK AUTOMATIC ASALYSIS :€‘roc. SOC. Atznlyt. Ckeni. TABLE 1 STAGES IN AUTOMATED ENZYME ASSAT Stage Operations required Prepare reagents from solids and stock solutions pare solutions Preparc reaction mixture from reagents Calculate required masses of solids or dilutions of stock solutions; pre- Calculate relative volumes of reagents and enzyme solution required to give reaction mixture of correct final composition. Mix reagcnts and enzyme solution in correct proportions and sequence Select suitable incubation conditions such as temperature and time of incubation; transfer reagents to incubation vessel ; start reaction Select suitable settings on sensor e.g.wavelength and slit width on a Incubate reaction mixture in suitable incubation vessel Follow course of reaction with a suitable sensor spectrophotometer Recovd output from sensor Select correct settings on recording device e.g. sensitivity chart speed; adjust recording device “g. set instrument zero adjust base-lines Calculate enzyme activity in suitable units from values on record ”g. from peak heights on chart recorder. Tabulate results and plot on suitable axis Calculate $naZ vesult from records Plan next experiment On the basis of the final result decide on assay conditions for next experiment and on any necessary instrument adjustments ing of data a t a central computer Institute and then prepared the reagents manually. How- ever there is no conceptual difficulty in connecting automatic pumps and diluters to an on-line computer so that the preparation of reagents could be carried out under direct computer control.The preparation of reaction mixtures could then be adjusted automatically if there were any variation in the behaviour of the pump lines in the analyser. TABLE I1 3IETHODS OF AUTOMATIKG OPERA4TIOKS REQCIRED I S TABLE 1 Stage Prepare reagents from solids and stock solutions Prepare reacizovl nzzxtzwe from reagents Incubate reaction mixture in suitable incttbation vessel Follow course of reaction xq-ith a suitable sensor Record output from sen~or Calculate final result froni records Plan next experiment Automated techniques available XVeighing by automatic balances; dilutions by proportioning pumps or autodiluters; calculations by computer Dilutions by proportioning pumps or autodiluters; mixing by jets or mixing coils; sample addition by automatic sampler units; calculations by computer Selection of incubation conditions by operator transfer to incubation ressel by pump or sampler; reaction started by addition of enzyme or substrate from sampler or automatic pipette Instrument settings best done by operator; in a “closed-loop” could be donc by on-line computer m‘ide variety of recording deirices now available including chart recorders digital output of various forms including paper-tape or direct BCD input into computer Calculations by computer; input either paper-tape magnetic tape or cards generated via ana1ogue:digital converter from sensor or nianually prepared by punching values read by operator from chart record Output usually via line printer but could be through teletype or visual display Fundamental decision about conditions for nest assay by operator.-4ssessment and storage of results aided by computer; possible use of computer in design of new assays e.g. by reference t o analytical data stores September 1973 THE USE OF EKZYMES IS AUTOklATIC AXALYSIS 233 The transfer of the reaction mixture prepared as above into the incubation vessel and the addition of enzyme or substrate to start the reaction are again readily automated with current equipment. A simple arrangement with the Technicon system is shown in Fig. 3.1 in Ref. 1. Substrate buffer and enzyme are mixed sequentially and then pumped into the incu- bation vessel which is a time-delay coil in a temperature-controlled bath.The reaction is then monitored in a continuous-flow colorimeter. In discrete sample analysers a large number of which are now commercially available (see Appendix I l l in Ref l) each sample has its own reaction vessel the sample cup or tube. Reagents are added from suitably positioned auto- pipettes and the entire “train” of reaction vessels moves through the incubation vessel until it passes under a suitable probe that measures the progress of the reaction (Fig. 4.5 in Ref. 1). In both types of system the volumes of reagents taken and the sequence in which they are added and mixed is determined in advance by the arrangement of the analyser “hardware.” In the case of the Technicon AutoAnalyzer this is the “manifold” with its particular arrange- ment of tubes joints mixing coils etc.; in the discrete sample analyser the operator arranges the positions of the various autopipettes along the sample train in advance and also sets the volume of fluid to be delivered by each pipette. Hence most of the analysers in current use are arranged so that alteration of the analytical system from one assay procedure to another requires physical modification to the machine configuration carried out by human operators. However again there is no conceptual barrier to the development of programmable systems with pumps and valves operated by an on-line computer. This would be particularly easy if analytical systems were arranged as packages of “standard” units. For example a “general- ised enzyme analyser” has been developed in our laboratory that can be adapted readily to a wide range of enzyme assays with very little physical modification to the component^.^ We are also currently developing generalised chemical analysers for example for protein amino- acid and Pi determinations.-4utomatic sensor and ancillary recording systems for following the progress of enzynie- catalysed reactions have been available for agreater number of years than other components of automated enzyme assay systems. One has onl?; to look through current advertisements in journals such as Laboratory Prnctice Science Fedtratioiz Proceedings and Analytical Chemistry to appreciate the great wealth of recording spectrophotonieters for example that are now on the market. The most complex systems have several or all of the following facilities powerful scale expansion dual wavelength measure- ment base-line correction automatic sample changers temperature-controlled cuvettes digital concentration read-outs digital print-out and other data processing facilities.Some sjTstems include a virtual on-line computer. In addition to automatic spectrophotometry there are automatic systems for measurement of fluorescence pH change light scattering heat changes and other physical parameters that may alter during the progress of the reaction. Hence there is no difficulty whatsoever in automatically monitoring the progress of the reaction. The final stage of the problem the conversion of instrument readings into suitable units (such as micromoles per minute) poses no problem to the computer which can of course do far more than this. \Ye have developed a series of FORTRAS programs which perform calcula- tions on and tabulate numerical data dealing with incubation times protein concentrations sample concentrations various gradient calibrations reagent and assay blanks and the actual readings obtained during the assay as well as handling textual material such as details of the samples used assay conditions notes and comments e t ~ .l > ~ - j (Some typical output has been published; see Table 7 in Ref. 3 and Fig. 9.13 in Ref. 1.) The main problem is not the comput- ing but lion to interface the analyser and the computer. In most of our early work we read the peaks on the XutoXnalyzer records manually and punched the values on to I.B.M. cards using a card-punch. This tedious process has now been eliminated in our laboratory by the use of a P.C.D. chart reader” which gives scaled X,Y co-ordinate values that are printed out on a teletype and on to paper-tape which is then read by the computer for further data pro- cessing.This is an efficient procedure because it allows for editing and sorting of “raw data” and so reduces the volume of paper-tape output which with a continuously operated multi- channel system can be very large indeed. Obviously the choice of data-logging equipment depends on the requirement of the laboratory and the funds available. In general the computational capabilities of current computers exceed any possible They therefore have the greatest sophistication. * Available from P.C.D. Limited 42 Queens Koad Farnborough Hampshire. 234 IPvoc. SOC. Analyt. Chew. demand from automatic analysers by several orders of magnitude.IVith the possible excep- tion of rapid reaction rate studies with stopped-flow systems most automatic enzyme analysers operate extremely slowly in comparison with the rate of computation. Even the most rapid discrete sample analysers have only been reported to operate a t 300 samples per hour. Hence the time scale for sample analysis is in minutes or at the best seconds; the time scale for currently used data input devices (such as card or paper-tape readers) is in milliseconds while the time scale of the central processor unit of the computer is in microseconds. Lye therefore have an enormous computing power in reserve and could clearly cope with great increases in the sampling rate of the enzyme analyser provided that interface problems could be overcome. The significance of the GemSXEC multiple cuvette rotor developed by -Anderson6 is obvious in this context.To conclude virtually all of the stages in an enzyme assay shown in Table I can be auto- mated by current equipment. However there has been uneven development in the various technologies involved particularly as regards rates of analysis ; there is therefore clearly great scope for future development. Some particular aspects of enzynie automation will now be discussed in a little more detail. Perhaps the most difficult current problem is the measurement of the reaction rate in a continuous flow analyser such as the Technicon AutoXnalyzer. The main error that may arise from single-time point determinations is that not all values will be in the linear region of the progress curve (see Fig.4.1 Ref. 1). Various interrupted flow systems have been described in the literature in which the enzyme is added to the reaction mixture automatically and the flow of reagents stopped while the progress of the reaction is followed in the cuvette of a recording spectrophotonieter (see Ref. 7 for example). Some discrete sample analysers can monitor the progress of the reaction after addition of enzyme (e.g.! the Pye Unicam AC61). -41~0 electronic devices have been described for calculating the initial rate from a series of readings taken while the reaction mixture is stationary in the cuvette as in the Gilford enzyme analysis system. However it is not easy to modify the Technicon system to interrupted flow and there are also considerable theoretical advantages in using a system in n-hich the rate of flow of fluid remains constant.By using time-delay coils relatively slo~v reactions that might take 15 to 30 minutes to give a suitable reading can be monitored a t the normal sampling rate (for example sixty per hour). An interrupted flow system for such an assay could only operate a t 2 to 4 samples per hour. Continuous monitoring of enzyme activitj. for example in the effluent of a chromatographic column is best carried out by continuous flow methods. The best method of obtaining the advantages of continuous flow with information on the pro- gress curve is to have a multichannel system with one channel for each incubation time (a four-channel system under development in our laboratory is shown in Fig. 5.7 in Ref. 1). The greater the number of channels the greater is the precision.Unfortunately the cost also increases; a reasonable compromise is to establish the range of assay conditions that gives linear progress curves and to check that assays fall within this range by using a two-channel system as was described several years ago.8 The continuous flow enzyme analyser is remarkably well suited to the automated study of certain fundamental properties of enzymes. This is readily achieved by incorporating suitable gradient-making systems into the analyser. \I?th these systems it is possible to study the effect of varying a variety of components in the reaction mixture. For example one can measure the effect of enzyme concentration on activity (Fig. 5 Ref. 4) and determine the optimum pH a~tomatically.~ Probably the most important use of gradient-making systems is in the determination of the effect of substrate concentration on enzyme activity and hence the Michaelis - Menten constant (K,).By providing a continuously increasing substrate concentration via the gradient maker one can measure K, with a (theoretically) infinite number of points (see Fig. 10 in Ref. 10 for example). IVhen linked with appropriate com- puter programs the system becomes a very powerful tool for the study of enzyme kinetics. I t is also relatively easy to alter the temperature of the reaction vessel so as to obtain a trace of the effect of temperature on enzyme actisrity (Fig. 9 in Ref. 10). Also one can readily monitor the stability of enzymes at various temperatures (as in Fig. 11 in Ref. 10). Such studies can give valuable information about the thermodynamics of the enzyme-catalysed re- action and useful data on the stability of the enzyme during storage.The use of these methods makes niultiparameter analyses of enzyme activity relatively easy. For example one can readily examine the effect of enzynie concentration on activity a t THE USE OF EsznviEs I N AUTOMATIC AKALYSIS September 19731 THE USE OF ESZYhfES I N AUTOMATIC .4SALYSIS 235 a number of incubation times or the effect of substrate concentration at a number of pH values. Suc.h analyses are best plotted as three-dimensional diagrams (see Fig. 12 in Ref. 10 for example). As more variables are examined problems of data presentation arise. One could 1iai.e a family of three-dimensional graphs in order to represent the results when more than three parameters are studied.However this is clearly an inadequate solution and there is a need to develop new methods for handling condensing and displaying the large masses of data than can be readily generated by automated multichannel systems. Again there is little doubt that the computer will play an important part in this development. -\part from the use of multichannel systems for following the progress curve once one has adequate funds it is possible to develop systems for the simultaneous assay of groups of en- zymes. The clinical multichannel systems such as the Technicon S l l h 12/60 are well known in this respect. For less cost we have developed a variety of “multienzyme analysers” l$A&lo-ls based on the following principles. The reaction mixture is prepared by mixing the enzyme preparation (e.g.a tissue homogenate) with buffer and appropriate co-factors. Differ- ent substrates are then introduced sequentially from the sampler unit into the flowing reaction mixture stream. The various enzymes present in the biological material then react in sequence as each appropriate substrate is sampled. Multiple enzyme analysis is a most useful type of analysis as it provides for the simultaneous measurement of a group of enzyme activities. In this nay it is possible to discern patterns and relationships between enzymes that would be tedious to establish by manual techniques. Some of the enzyme “patterns” studied in our laboratory include measurement of groups of phosphatases Y-iD- and SADP-linked dehydro- genases hexacyanoferrate(II1) reductases and DCPIP-reductases.As with the tnulti- parameter analysis mentioned above multiple enzyme analysis is a good “data generator,” and one has to be careful to keep the data processing in step with the experiments. Certainly new approaches to data handling will have to be developed as the multi-assay q-stems become faster and more sophisticated. It is hoped that this paper has shown some of the very promising techniques and approaches that are now possible for the automatic study of enzyme activity. The variety of analytical systems now available is very great as is the choice of data processing and computing systems. The problems of effective enzyme automation are therefore essentially problems of cost effectiveness and systems analysis. Stated in an extreme way one can say that we are now in a position where the question is not how to assay a given enzyme or group of enzymes but rather how to use most effectively the finances that are available for such assays to purchase or e\.en rent the most suitable equipment both for the actual analysis and for the subsequent data processing.These problems are particularly acute for those who are not committed to pre-existing hardware in their laboratories. The choice could become even more difficult if there is an increased move in the future towards capital-intensive “analytical centres” analo- gous to the present computer centres. There is little doubt that the climate in which enzyme as.;a!.s will be carried out in the next 10 years will be very different to that prevailing today. 1. 2 . 3 . 4. 6 . 6. 8. Y . 10. 11. 1’. 13. 14. 15. r REFERENCES Roodyn D B “Aiutomated Enzyme Xssavs,” Sorth Holland Amsterdam 197U Jowett G K “An Introduction t o .Automated Enzvme .\nalvsis ” Koch-Lqht Laboratories Colnbrook 1970 Roodyn D B Bzocikewz 1 1970 119 823 Roodvn.D B and Marotidas N G Analvt B Z O C ~ E I ~ 1968 24 196 Roodvn D. B. in “Automation in Analytic&l Chemistry Technicon Symposium. London 1969,” Anderson N. G. Analyt. Biochem. 1969 28 545. Pitot H. C. IVratten JI. and Poirer >I, I b i d . 196s. 22 369. Roodyn D. B. Satwe Loizd. 1967 216 1033. Tappel X. L. and Beck C . in “Alutomation in Analytical Chemistr)- Technicon Symposium Roodyn D. B. Process Btochem. 1969 4 57. - Sattwr L o i d 1968 206 1226. - in “Xutomation in Analytical Chemistry Technicon Symposium 1965,” 3lediad Press - in “Automation in Analytical Chemistrl- Technicon Symposium 1967,” \-olume 11 Roodyn D . B. and Wilkie U. Biochem. J . 1967 103 3c Jowett G. K. and Roodyn D. B.. in “Xutomation in Analytical Chemistry Technicon Symposium London 1969,” Technicon Chertsey 1969 pp. 25-31. Technicon Chertsey 1969 pp 23-26. 1966,” hlediad Press Yew York 1965 pp. 559-562. Ken. York 1965 pp. 593-591. Mediad Press New Yorli 1967 pp. 233-5237,

ISSN:0037-9697    

DOI:10.1039/SA9731000230

出版商:RSC    

年代:1973

数据来源: RSC

摘要:

236 PHYSICAL ANALYSIS IN CLINICAL CHEMISTRY ‘Proc. Soc. Afzalyt. Chem. Newer Physical Methods of Analysis in Clinical Chemistry The following are summaries of two of the papers presented at a Joint Meeting of the North East Region with the Association of Clinical Biochemists held on April l l t h 1973 and reported in the Nay issue of Proceedings (p. 100). Introductory Remarks BY C. TOOTHILL (Departzizeizt o j Chemical Pathology Cn$vers$ty of L e e d s Leeds LS2 9 S L ) THE introduction of the flame photometer and photoelectric spectrophotometer in the period 1940 to 1950 increased the scope of the clinical chemist. Initially he was a person of high manipulative skill but he has gradually become a person intimately concerned with hospital medicine in addition to his original r61e. Clinicians now not only expect specimens to be analysed accurately but on many occasions wish to have small samples analysed.The introduction of the Technicon AutoAnalyzer in 1957 and subsequently other forms of automatic analytical equipment has enabled the clinical chemist to meet these ever- increasing requests from his clinical colleagues. Amongst all this the clinical chemist must think about and attempt to plan for his future contribution to the practice of medicine. In an attempt to help us consider the future our colleagues have organised this meeting. Broadly speaking the methods we use are of two types-firstly those in which a com- pound is determined by a specific or relatively specific method without unrecognised interfer- ence from other compounds that may be present ; and secondly analysis by “group specific” methodology after suitable separation procedures-this is usually undertaken for identification and subsequent quantitation.Broughton and Dawsonl in their recent discussion of instrumentation in clinical chemistry have listed nine principal forms-( 1 j ultraviolet and visible spectrophotometers ; (2) fluori- meters and phosphorimeters; (3) infrared spectrometers; (4) chromatography; (5) particle spectroscopy; (6) electrometric methods-ion-specijc electrodes; (7) micro- and radio-wave spectroscopy-?zuclear magnetic resolzance; (8) nucleonics and S-ra).-rndiochei?2icnl (radio- iwmunoassay) ; and (9) atomic spectroscopy-ntonzic absorfitioii. The first two in this list are the basis of the first type of analytical work which forms the bulk of our routine work.Infrared spectroscopy and chromatography are examples of the second type of methodology with which we are involved. chromatography coupled with mass spectrometry is an example of a group that has been well exploited by workers in the field of drug metabolism and in the investigation of inborn errors of metabolism.? My reference to drug metabolism was intentional as I think that as we become more involved with determining not just the total amount of drug or metabolite in biological fluids but the active concentration of the compound a t tissue level we will have t o turn to methods and instrumentation that are capable of sensitive fast and accurate analyses. Furthermore as investigations of intracellular biochemical function in disease become more frequent as suggested by Baron,3 small specimens will be the rule.Examples of the instrumentation shown in groups (6) to (9)> which have recent and successful applications in clinical chemistry form the basis of the four lectures a t this meeting. Some of these techniques will enable us to learn more about the standard methodology used daily. Although it does not receive consideration here high-speed liquid chromatography4 is a recent development that has enormous potential in giving us yet another analytical tool for the investigation of chemical changes in disease. Scott5 has recently reviewed this field with particular reference to systems for examining related compounds of biochemical interest for example ultraviolet-absorbing compounds and organic acids-recent work indicates that there are more than 500 constituents in urine changes in the concentration of many of which could be of pathological significance.There has been much discussion recently of the need in certain situations for “coin- operated” or “self-service” laboratory investigations a small volume of blood from a patient being examined automatically for a wide range of constituents by sensitive methods. September 19731 PHYSICAL ANALYSIS IiY CLISICAL CHEMISTRY 237 \I.’ith the minimum demand upon the operator this would enable more use to be made of the professional worker’s time in full interpretation of the results and suggestions for further investigations and/or treatment. The developments discussed in the lectures a t this meeting are therefore important in the future of our speciality so much so that education in these topics should not be left to purely post-graduate activities such as this one-undergraduates should be made aware of the potential of up-to-date techniques.The techniques described at this meeting are a far cry from the instruments upon which our subject was so surely based for example the Van Slyke gasometric analysis apparatus and the \Varburg flask and manometer. These two workers by a judicious choice of established chemistry enabled a wide range of compounds to be assayed in biological fluids. Let us hope that we use our new apparatus with the same intelligence and knowledge that our illustrious predecessors did. REFERENCES 1 . 2. Broughton P. 31. G. and Dawson J. B. .4dv. Cliit. Chcm. 1972 15 288. lellum. E.. Stokke. 0.. and Eldiarn. L,. rn Stern T . and Toothill.C.. Editovs “Organic Acidurias 9th S>-mposium S.S.’I.E.JI.,”’Churchlll Livingstbne Edinburgh and London 1972. 3. 4. 5 . Baron D. Clin. Chew. 1972 18 320. Done J. pi. Kennedy G. J . and Knox J. H. Satuve Lond. 1972 237 75. Scott C. D. Adv. Clin. Chew. 1972 15 1. Ion-selective Electrodes B Y w. G. ROBERTSON AND R. 157. lIARSH.1LL (a’iI,R,C -W’ineval ;letabolistn Unit The General Injivnzavy Leeds LS1 3 L X ) SISCE the development of the glass electrodel a t the beginning of this century for the measure- ment of pH yarious workers have attempted to construct electrodes selective for other ion^.^,^ It was not until the late 1950s however that further glass electrodes were successfully developed that were selective to other univalent cations4 The growing demand that followed in industrial and biochemical research for electrodes sensitive to divalent cations led eventually in the 1960s and 1970s to a new generation of electrodes none of which used ion-sensitive glass.The main types were the heterogeneous membrane electrodes the solid-state crystalline electrode,6 the liquid ion-exchange membrane electrode6 and more recently the multi-purpose electrode or “selectrode’l.i For biological work the most commonly used electrodes are the glass electrodes for measuring the concentrations of H+ NaT I<+ and NH,+ ions; the solid-state electrode for F- ions; and the liquid ion-exhange electrode for Ca2+ ions The object of this paper is to discuss individually the usefulness of these electrodes in clinical research and some of the advantages and disadvantages of each electrode.The pH electrode is probably the most widely used measuring device in biological research and is so commonplace that perhaps its capabilities and limitations are not always appreciated. The demands of medical research are often exacting e.g. the electrode may have to be sterilised between measurements and special glasses have had to be formulated to oi-ercome leaching of alkali metal ions at sterilisation temperatures Yoreover pH electrodes have had to be designed in various forms flat for skin measurements capillary for blood inrasurements and fine-probe for intracellular measurements. In general pH electrodes are fairl? robust although errors are caused by interference from sodium ions at high pH levels (the “alkaline error”) interference from adsorbed protein and interference caused by colloidal material in suspension such as red cells (the “Pullmann effect”).Glass electrodes for the measurement of Na- E i t and SH,- ions are also widely used in medical research and for Na- ions a t least have been shown to be more precise than conven- tional emission photometry.8 As Na+ and K’ ions are only weakly complexed to most bio- logical anions the “free” ionised concentration of each ion as measured by the electrode is virtually identical with the total concentration measured by the emission photometer. The main disadvantage of these electrodes is that although the sodium electrode is highlp selective 238 PHYSICAL AKALYSIS IS CLIXICAL CHEMISTRY [PYOC. SOC. Amlyt. Chenz. for Naf over KT ions the potassium electrode is not highly selective for K- over the Sa- ions.4s most extracellular fluids contain an excess of Na- over I<+ ions this means that Na- ions interfere to a major degree in the measurement of K- ions. This problem has been largel!. overcome with the recent development of the highly K+-selective liquid ion-exchange electrode based on the neutral molecule valin~mycin.~ The solid-state fluoride electrode in which a single crystal of lanthanum fluoride is used as the sensor has also been used in biological workloJ1 but is restricted to solutions in the p1-I range 4 to 8. Below pH 4 the F- ion is increasingly complexed to hydrogen ions therebl- reducing the concentration of free fluoride ions. Above pH 8 the fluoride electrode is more sensitive to OH- than to F- ions and falsely high readings are recorded. In biological work the most widely used ion-selective electrode apart from the pH electrode is that of calciuml2~13 because of the great importance of ionised calcium not only within the field of calcium metabolism itself but also in the functioning of many biological processes.The electrode has been shown to nork in serum13 and urine12 although there are problems from interference. The high S a - to Ca2- ratio in serum and urine is sufficient to cause some loss in specificity and standards should be used that contain the same concentration of sodium as the sample to be measured.12 The variability of ionic strength in urine also causes problems as the electrode responds to changes in the activity rather than the concentra- tion of calcium ions. In conclusion we can say that although ion-selective electrodes suffer from the dis- advantage that they are only selective and not specific towards a particular ion they have many advantages over existing methods and have been shown to be of value in biological research.The electrode method is quick does not require large volumes of sample is in many intances more precise than other existing techniques and there is no lass of sample during nieaurement. The ion-selective electrode will no doubt find many more applications in the clinical laboratory in the future. Again this can be overcome by the use of appropriate standards.12 RE FE RE sc E s 1. 2. 3. 4. 5 . 6 . r 8. 9. 10. 11. 12. 13. Haber F. and Klemensiewicz Z. Z. 9 h y s . Ciiew. 1909 67 355. Tendeloo H. J. C. J . Bid. Chem. 1936 113 333. Tendeloo H. J. C. and Krips Eisenman G. Kudin D. O. and Casby J. V Science X . Y . 1957 126 831. Pungor E. Havas. J . and Tbth K. Acta Chint. Huwg. 1964 41 139. Ross J. \T. in Durst R . X. Editor “Ion-Selective Electrodes,” X.B.S. Special Publication KO. 314 Ruzicka J. Lamm C. G. and Tjell J. C. Analyticn Chznz. d c t a 1972 62 15. Moore. E. \V.. ART?. -\-.Y. Acnd. Sci.. 1968. 148. 93. Red Trav. Chiin. Pay-Bas Bsige 195i 76 703. r . S . Government Printing Office Washington D.C. 1969. Frant,’ 41. S. and Ross J . W. S c i e k e -.V.kl, 1970 167 9 8 i . Fry B. \T. and Taves 1). R. J . Lab. Clin. &Meled. 1970 75 1020. Barnes F. \V. and Runcie T. 7. Clin. Path. 1968 21 665. Robertson \V. G. C l z a C h z k Acta 1969 24 149. Moore E. IT. J Clzn. Invest. 1970 49 315.

ISSN:0037-9697    

DOI:10.1039/SA9731000236

出版商:RSC    

年代:1973

数据来源: RSC

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238 PHYSICAL AKALYSIS IS CLIXICAL CHEMISTRY ~PYOC. SOC. 4 m l T t . Chenz Standardisation of Methods and Materials The following is a summary of one of the papers presented a t a Meeting of the S I C Analytical Division held on May 2nd 1973 and reported in the May issue of Proceedings (p. 99). The Preparation of Standard Chemical Substances BY J. E. COSNETT STASDARD chemical substances can be regarded as members of the class known as standard or certified reference materials. Standard reference materials may be certified for chemical composition or for some physical property. This paper is concerned mainly with those organic compounds which are available from the Division of Chemical Standards of the Sational Physical Laboratory; they fall mainly into the former category being certified with respect to chemical purity.(Ditsision ofchemical Standavds Satzonal Physical Labovatovy Trddington YTliddlesex TWll 0LT.I:) September 19731 STANDARDISATIOX OF METHODS ;\SD NATERIALS 239 Such reference materials are available from a number of sources. The Sational Bureau of Standards supplies a very large range of standard reference materials but most of those cliaracterised for composition are metals or alloys. The relatively few organic standard reference materials include clinical standards (e.g. cholesterol and urea) mistures of liydro- carbons a small number of “rare” and isotopically labelled compounds and some micro- analytical standards. 4 much larger source of organic standard reference niaterials is the .\.P.I. stock of reference hydrocarbons which includes some organic sulphur and nitrogen compounds.These materials were purified by methods including fractional distillation differential formation of urea adducts adsorption chromatography on silica gel solvent crystal- lisation and zone refining; most have a certified purity about 99.9 mole per cent. In the U.K. reference samples of pharinaceuticals are available from the British Pliarma- cupoeia Commission and several chemical supply houses offer organic analytical standards to specifications drawn up by the Society for .Analytical Chemistry. -1 number of organic corn- pounds of stated high purity originating from American suppliers are obtainable from U.K. distributors. In addition to those materials forming the principal topic of this paper other Divisions of the K.P.L. supply radiochemical electrical and magnetic standards ceramic tile colour standards and powders having certified surface areas ndiile the Division of Chemical Standards certifies for subsequent sale by a commercial supplier samples of benzoic acid for determinations of energy of combustion and samples of potassium hydrogen phthalate for p H determinations.The standard reference materials available from the Division of Chemical Standards fall into three groups organic compounds pesticides and thermometric standards. The prepara- tion of organic standard reference materials was begun in 1949 with a number of h!-drocarbon samples. total of 110 standard reference materials is now available; about half of these are Ii>.drocarbons and the remainder includes alcohols phenols ethers ketones and aniines.These standard reference materials are certified for purity which is usually about 99.9 mole per cent. andeach is supplied together with a certificate which states the purity and the method by \\.Iiicli it was determined. Gas samples are supplied at atmospheric pressure in 6OO-cm3 glass ampoules fitted with break-tip seals to facilitate connection to the user’s vacuum line and licluids and low-melting solids are sealed in ! ~ C L I O in i?-cn13 ampoules also fitted with break-tip seals or in plain Lcm3 ampoules. Higher melting solids arc available as 1-g samples in stoppered vials. \l.ork on standard reference samples of pesticides was begun in 1966; fiftj-three com- pounds are currently offered and a further ten are in preparation. They are recommended by (7,1,P.-4.C for use as reference standards in analytical procedures.Samples normally of 1 g are supplied together with acertificate stating the purity usually about 99 inole per cent, and thc. assay metliod used. Samples of benzene (200 cm3) certified with respect to freezing-point when saturated with water are available primarily for use in the STPTC Test Method RLB 24-67 and in the forthcoming amendment of British Standard 135. They are intended as a means of calibrating the thermometers to be used in these tests although they can be used for any purpose that requires aii accurate knowledge of the temperature scale a t about 5.3 ‘C. Most of the materials used to prepare standard reference niaterials originate from corn- niercial suppliers and a number of purification techniques are available to bring the samples to the required high purity.The Division is equipped with a variety of high-efficiency fractional distillation columns fitted with automatic control and alarm systems. Liquids unsuitable for purification by distillation can sometimes be purified by a hatch fractional freezing technique in wliich the bulk material is frozen by slow cooling or by a modification of this technique in \ ~ h i c l i a tube containing the sample is slowly lowered into a freezing-bath. If freezing mctliods also fail preparative gas cliromatography may be successful. Solids are usually purified by zone refining sometimes after preliminary solvent crystallisation and this tecli- niclue can be extended to certain liquids by operating the equipment in a refrigerator. Frac- tional vacuum sublimation has been successfully applied to some pesticides resistant to purification by other methods.Gas chromatography is used to check initial purity to monitor the course of purification and to determine the water content of liquid samples. If no other method is suitable gas chromatography can also be used as a final assay method and in this event the sample would The Division offers at present only one thermometric standard. 240 STAXDARDISATIOK OF METHODS AKD NATERIALS [Proc. SOC. Aaaiyt. Cizetn. be analysed on several different chromatographic columns so as to improve the chances of resolving all the impurities. If possible the final purity is assessed by thermal analysis for which three separate techniques are available. Observation of melting behaviour by adiabatic calorimetry is the preferred method and although the complex instrumentation required is not a t present available within the project on standard reference materials a purity arrived at by this method may be available if the sample is used for thermodynamic measurement else- where in the Division.The second method time - temperature cryoscopy is normally used for samples that are liquid a t ambient temperature. The sample is slowly cooled by extraction of heat a t a steady rate while periodic measurements of sample temperature are made. Analy- sis of the derived time - temperature freezing curve provides a value for the purity of the sample if the heat of fusion of the pure material is known. If it is not known the measure- ments are repeated under the same conditions with a sample to which a small measured amount of a suitable impurity has been added.The purity of the original sample can then be obtained. The third method differential scanning calorimetry is used primarily for solids and is suitable for most pesticides. A standard commercial instrument has been modified by the addition of data handling equipment which produces a paper-tape output. This is used to feed the results of the measurements to a computer which using a program written in the Division provides a print-out of the purity and energy of fusion of the sample. Other methods of purity assess- ment sometimes used are mass spectrometry especially in association with gas chromatography and infrared spectrometry. Probable future developments include the provision of a series of solid thermometric standard reference materials certified for melting-point and if required for energy of fusion and the development of improved analytical facilities including linked gas chromatography - mass spectrometry. This is expected to be increasingly useful in particular for identifying trace impurities in standard reference materials.

ISSN:0037-9697    

DOI:10.1039/SA9731000238

出版商:RSC    

年代:1973

数据来源: RSC

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240 STAXDARDISATIOK OF METHODS AKD NATERIALS [Proc. SOC. Aaaiyt. Cizetn. Papers Accepted for Publication in The Analyst THE following papers have been accepted for publication in The Analyst and are expected to appear in the near future. “Monte Carlo Simulation of Matrix Correction Effects,” by R. J. Howarth. “Voltammetric Analysis of Tocopherols By Use of a Newly Developed Carbon Paste Electrode,” by Samuel Atuma and Jorgen Lindquist. September 19731 PlPERS ACCEPTED FOR THE ASALTST 241 “Application of the Carbon Cup Atomisation Technique in \Vater Analysis by -Atomic- absorption Spectroscopy,” by F. Dolinsek and J. Stupar. “Some Considerations about the Complex Formation Titration of Xluminium a t Diff- erent Concentration Levels,” by J. Kragten. “Determination of Alpha- Reta- Gamma- and Delta-BHC Residues in Human Blood Adipose Tissue and Various Organs,” by G.Czegledi- Janko. “Polarographic Studies of the Zinc(I1) Complex Formed with Tyrosine in dqueous and Mixed Aqueous and Son-Aqueous Nedia,” by Daya Nand Chaturvedi and C. 11. Gupta. “The Determination of Nifursol in Animal Feeds,” Report Prepared by the Prophylactics in Animal Feeds Sub-committee of the Analytical Methods Committee. “Gas-chromatographic Analysis of Polyurethane Polyethers by Using a Xixed Anhydride Reagent for the Cleavage of Ether Linkages,” by Kazuro Tsuji and Kazuo Konishi. “The Determination of Quindoxin in Compound Animal Feeds and Pre-mixes,” Report Prepared by the Miscellaneous Additives in Feeds Sub-committee of the AAnalytical Methods Committee. “The Determination of ru’itrovin in Compound Animal Feeds and Pre-mixes,” Report Prepared by the Miscellaneous Additives In Feeds Sub-committee of the .Analytical Methods Committee. “Absorptiometric Determination of Trace Amounts of Sulphide Ion in JVater,” by A. Y. Salim S. A. Rahim and 1liss S. Shereef.

ISSN:0037-9697    

DOI:10.1039/SA973100240b

出版商:RSC    

年代:1973

数据来源: RSC

摘要:

September 19731 PlPERS ACCEPTED FOR THE ASALTST 241 Publications Received The publications listed below have been received by the Editor of Tile .-l?zaZyst in Ivhich journal Book Reviexvs will continue to appear. Pp. x - 47. London H.X. Stationery Office. 1973. Price 03p. SI. THE INTERNATIOSAL SYSTEM OF UNITS. Edited by CHESTER H. PAGE and PAUL \ 7 ~ ~ akS.\LYTIChL CHEATISTRY-4. P L E S A R Y LECTURES PRESEKTED AT THE I N T E R S l T I O S A L COX- GRESS ON -kSALYTICAL CHEAfISTRY HELD AT IIYOTO JAP.%S 3-7 -kPRIL 1972. ISTERKATIOKAL UXIOS OF P U R E AXD APPLIED CHEhIISTRT A\NALYTICAL CHEATISTRY DIT'ISIOS I S C O T JCSCTIOS WITH THE SCIESCE COUSCIL OF JAPAN. London Butterworths. 1973. Price i 5 ; $15. Symposium Editor hIIrsucr SESDA. Pp. 1.i + 170. THI~ORY OF SPECTROSCOPY. h ELEhlENTARY INTRODCCTIOS.BY OLIVER HOIYARTH. Pp. s - 214. 1973. London Sairobi Melbourne Don bIills and Lagos Thomas Selson ti Sons Ltd. Price L4.50 (hardback) ; L2.25 (softback). PAR.IMAGSETIC LANTHANIDE SHIFT REAGENTS IK SJIR SPECTROSCOPY PRISCIPLES METHODO- By J. REUBES. Progvess i?2 Ayf.rclenv -Vlaguetac Resouame Spectro- Pp. viii + 70. Oxford New Uork Toronto Sydncy and Braun- By \-. G. BEREKIK and \-. S. TATARIS- S e w York and London Consultants LOGY AKD APPLICATIOXS. scopy T'olunze 9 Part 1. schlveig Pergsmon Press. 1973. Price L 2 . GAS-CHROMATOGRAPHIC ANALYSIS OF TRACE I i w c R m E s . Translated by J. E. S. BRADLEY. SKII. Bureau. 1973. Price S34. Pp. s - 177. FUSDAR.IENTAL -4SPECTS AND I<ECEKT DEVELOPMESTS IK OPTICAL ROTATORY DISPERSIOS ASD CIRCULAR DICHROISM. PROCEEDISGS OF XATO ~ D V A X C E D STUDY IKSTITUTE HELD AT TIRRENIA (PISA) 5-18 SEPTEMBER 1971.Edited by F. CIARDELLI and P. SALT'ADORI. Pp. xviii + 419. London Yew York and Rheine Heyden & Sons Ltd. 1973. Price L l l ; $30.25; DiLI9O. 242 PUBLICATIOSS RECEIVED IProc. SOC. A nnlyt. Chena. .~DVANCES IS KAZTAN SPECTROSCOPY. 1701ume 1. PROCEEDISGS OF THE THIRD ISTERNATIOSXL CONFERENCE ON Ra~ahr SPECTROSCOPY UNIVERSITY OF REIm FRASCE SEPTEMBER 1972. Edited by J P. MATHIEU. London K e w York and Rheine Heyden & Son Ltd. 1973. BASIC ORGASIC REACTIOSS. By IT. XICCRAE. Pp. xiv f 216. London S e \ r York and Rheine Price L3.60; $9.90; DnT29.50 (harcl-back); L1.95; $5.35; DM16 Volume 2. (TG- DTG- DTA-CURVES ~IEASURED SINTL- TANEOUSLY). Edited by G. LIPTAY. Pp. 161. I>ondon Sew Torli and Kheine Heyden & Son Ltd.1973. Price i11.50; S31.65; DA194.50 (loose-lcaf). Sew Tork Cincinnati Toronto and Melbourne Van Kostrand lieinhold Co. i i . 5 0 . Pp. xiv + 639. Price A16; S44; DlI131.50. Heyden & Son Ltd. 1973. (soft-back). ; ~ T L X S OF THERMOASALYTICAL CURVES. THERMOMETRIC AND ENTHALPINETRIC TITRI~IETRY. G. X. 1-AUGHAS. Pp. xi\- 2 5 5 . London 1973. Price ~-TITROSO Conipouxm ANALYSIS AND FORZIATION. PROCEEDISGS OF A \\.ORKING CONFERE HELD .4T THE DEUTSCHES KREBSFORSCHUNGSZENTRUZT HEIDELBERG FEDERAL r<EPUBLlC OF GEKMAXY 13-15 OCTOBER 1971. Edited by P. BOGovSIcr R. PKEUSSZIA and E. \TALKER. Technical Editor for IARC W DAVIS. IARC Scie?it?fc Pzrblicntion -Y 3. Pp. s y i - 140. Lyon International Agency for Research on Cancer. An I?qtet,natioiinl Scvies of Jlanogmpizs S o . 3. Pp. yiii - 190. Lolidon and Sew Yorlc -Academic Press. 1 9 7 3 Price L4-50. Pp. sx - 379. Aylesbury Leonard Hill Books. 1973. Price ~ ~ 8 ~ 5 0 . s v i - 634 Xcw Tork London Sydney and Toronto \~iley-Intcrscience. 1973. Price 197.'. QC.ASTITATIVE XNALYSIS B Y XlIR SPECTROSCOPY. By F. KASLER. SUGAR COSFECTIOSERY AND CHOCOLATE ~IASUFACTURE. By R. LEES and E. 13. JACIWJS. KE.4CTIOS ~IIiCH.lSIS3IS I S ORGANIC .\SALYTICAL CHEMISTRY. l j y I< -ETH ;I. C O S S O R S . f'p. 19.25. RASDO~I >'ULSE TRAINS THEIR hIEASURE3fEXT ASD STATISTIC.lL PROPERTIES. By C . H. \ - I S C E S T . Pp. s i v + 264. IEE 3Ionog~nplz Series 13. the Institution of Electrical Engineers). 1973. Price ,t.7*50. London Peter Peregrinus Ltd. (on behalf of

ISSN:0037-9697    

DOI:10.1039/SA9731000241

出版商:RSC    

年代:1973

数据来源: RSC

摘要:

242 PUBLICATIOSS RECEIVED IProc. SOC. A nnlyt. Chena. Erratum -~L-GTST (1973) ISSUE p. 222 line 29. For “Johnson Matthey Metals Ltd.” read “Johnson Matthey Chemicals Ltd.”

ISSN:0037-9697    

DOI:10.1039/SA9731000242

出版商:RSC    

年代:1973

数据来源: RSC