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of the Society for Analytical Chemistry CONTENTS New Honorary Member . . 155 International Atomic Absorp- tion Spectroscopy Conference International Symposium on Analytical Chemistry Birm- Sheffield 1969 . . . . . . I56 ingham I969 . . . . . . I 59 Summaries of Papers “Radiochromatographic Analysis” I62 “Inertial Methods of Particle-size Analysis” . . .. .. 167 “Why Particle-size Analysis ?” . . I69 Membership Changes . . . . 176 Papers Accepted for The Analyst I76 Publications Received . . . . 177 Notices .. .. . . .. 177 Announcements . . . . . . 179 Forthcoming Meetings Back cover roc. SOC. Analyt. Chem. vol. 6 No. 9 Pages 155-180 September 1969 Vol. 6 No. 9 PROCEEDINGS OF September I969 THE SOCIETY FOR ANALYTICAL CHEMISTRY President of the Society T. S. West Hon. Secretary of the Society W.H. C. Shaw Hon. Treasurer of the Society G. W. C. Milner Hon. Assistant Secretaries of the Society D. 1. Coomber; D. W. Wilson Secretary Miss P. E. Hutchinson 9/10 SAVILE ROW LONDON WIX IAF Telephone 01-734 6205 Editor J. B. Attrill Telephone 01-734 3419 Proceedings is published by The Society for Analytical Chemistry and distributed to all members of the Society and t o subscribers with The Analyst; subscriptions cannot be accepted for Proceedings alone. Single copies may be obtained direct from the Society’s Distribution Agents The Chemical Society Publications Sales Office Blackhorse Road Letchworth Herts. (NOT through Trade Agents) price 0 The Society for Analytical Chemistry 5s. post free. Remittances MUST accompany orders. Joint Symposium on Accurate Methods Tor Major Constituents organised under the auspices of the Society for Analytical Chemistry and the Analytical Section of the Royal Dutch Chemical Society will be held at Imperial College of Science and Technology London Friday and Saturday April 3rd and 4th 1970 Preliminary Registration Forms were inserted in the July issue of The Analyst and should be returned as soon as possible to The Secretary The Society for Analytical Chemistry 9/10 Savile Row London WIX IAF.

ISSN:0037-9697    

DOI:10.1039/SA96906FX029

出版商:RSC    

年代:1969

数据来源: RSC

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THE SOCIETY FOR ANALYTICAL CHEMISTRY 179 Forthcoming Meetings-continued October Wednesday 8th I>ONDON Wednesday 15th BIRMINGHAM Wednesday 22nd IPSWICH Thursday 23rd LONDON MICROCHEMICAL METHODS GROUP London Discussion Meeting. Discussion on “The Microdetermination of Fluorine-Specific Ion Electrodes Leicester Lounge Glasshouse Street London W. 1 ; 6.30 p.m. MIDLANDS SECTION Meeting on “Computer Applications.” vevsus Other Methods,” to be introduced by T. K. F. W. Fennell. Speakers to include J . F. Becker W. Kelly P. Mitchell J. Newel1 and R. K. Webster. The University Birmingham; 2.30 p.m. EAST ANGLIA SECTION Annual General Meeting. “Amplification Reactions ” by Professor I<. Belcher. Civic College lpswich; 3 p.m. I~IOLOGICAL METHODS GKOUP Meeting on “Detection and Estimation of Pharmaceutical Society 17 Bloomsbury Square London W.C.l; 5 p.m.Antiviral Substances. ” THE SOCIETY FOR ANALYTICAL CHEMISTRY Forthcoming Meetings September Wednesday 24th COVENTRY Wednesday 24th BRISTOL Wednesday 24th BRADFORD Thursday 25th MOTHERWELL October Wednesday 1st LONDON Saturday 4th LIVERPOOL Tuesday 7th EDINBURGH Tuesday 7th BELMONT MIDLANDSECTION on “Membrane Electrodes.” Speakers I<. A. Carter Lanchcster College of Technology Priory Street Coventry; 6.30 p.m. WESTERN SECTION and ATOMIC-ABSORPTION SPECTROSCOPY GROUP jaivltly with the Bristol and District Section of the Royal Institute of Chemistry on “Applications of Atomic-absorption Spectroscopy.” “The Use of Atomic-absorption Spectroscopy within the G.K.N. Group,” by I<. M. Baldwin. “Some Applications of Atomic-absorption Spectroscopy to Agricultural Analysis,” by T.Williams. “Determination of Silver and Gold in Raw Materials and Products of Zinc and Lead Smelting,” by H. Edwards. “A Consideration of Performance Capabilities of Atomic-absorption Spectro- photometers in Relation to Design Characteristics,” by R. J. Reynolds. School of Chemistry The University Bristol; 11 a.m. PARTICLE SIZE ANALYSIS GROUP. “Current Research in the School of Powder Technology a t the University “Surface Area Determination by the Diffusion of Air Through Packed Beds of “Flow Microcalorimetry,” by R . M. Patel. “X-ray Sedimentometer,” by L. Svarovsky. Lecture-demonstration on “Particle Sizing by Automatic Image Analysis,” Lecture Theatre B.4.1 Chemical Engineering Building The University SCOTTISH SECTION.“X-ray Fluorescence and Emission Spectroscopy in Steelworks Analysis- Main Lecture Theatre Motherwell Technical College Knowetop Motherwell ; G J . Kakabadse and A. M. G. Macdonald. of Bradford,” by J . C. Williams. Powder,” by N. G. Stanley-Wood. by A. C. Tcrrell. Bradford 7 ; 2.30 p.m. Competitive or Complementary?” by K. M. Bills. 4 p.m. SOCIETY. “Computerised Titrations-Unravelled Stoicheiometry and High Accuracy ” Geological Society of London Burlington House Piccadilly London W. 1 ; NORTH OF ENGLAND SECTION. “Industrial Aspects of Food Analysis,” by A. Turner. Lecture Theatre City Laboratories Mount Pleasant Liverpool; 2.30 p.m. SCOTTISH SECTION jointly with the Edinburgh Branch of the British Computer Society. “Computerised Titrations-Unravelled Stoicheiometry and High Accuracy,” by Professor I>. W. Dyrssen. Computer Applications Unit Mountbatten Building Heriot-Watt University Grassmarket Edinburgh; 5.30 p.m. NORTH EAST SECTION Annual Dinner. “Close-ups in Colour,” by W. R. Lovesey. Ramside Hall Hotel Belmont Nr. Durham; 7 p.m. by Professor D. W. Dyrssen. 7 p.m. [continued on inside back covey Printed by W Heffer & Sons Ltd Cambridge England

ISSN:0037-9697    

DOI:10.1039/SA96906BX031

出版商:RSC    

年代:1969

数据来源: RSC

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September I969 Voi. 6 No. 9 PROCEEDINGS OF THE SOCIETY FOR ANALYTICAL CHEMISTRY New Honorary Member Dr. Alan Walsh ALAN WALSH was born in England at Ilarwen Lancashire in 1916. He was educated at Darwen Grammar Scliool and later graduated in physics at Manchester University. His first post was with the Kritish Non-ferrous Metals Research Association which he joined in 1939 arid served until 1946 including one year at the Ministry of Aircraft Production. He went to Australia in 1046 when he joined the Commonwealth Scientific and Industrial Research Organisation. He is now Assistant Chief in the Division of Chemical Physics. At the K.N.F.M.R.A. he designed an excellent general-purpose source-unit for emission spectro- scopy known as tlie “Walsh Circuit,” and he gave cheerful assistance in developing the conimercial form of this.In Australia he worked with obvious enthusiasm with the Fraunhofer lines. He had developed this interest as a result of having to begin a prograiiinie of work in a small way; not wishing to study fashionable topics on which teams of Ph.D. research workerswere already working with equipment unlimited by cost he had looked for a neglected field of study. The result was the development of atomic absorption. His original desire was (and still is) to use the method for determining oscillator strengths of atoms rather than for chemical analysis although lie realised what a powerful tool it would prove for the latter purpose and lie welcomed it. (Atomic absorption can be treated classically and by quantum theory. To connect these two treatments the oscillator strength f,, is used it is defined for the transition 13 to y as the number of harmonically vibrating electrons which would together have the same absorption as one atom in the state p.The early years of atomic absorption were disappointing to him because of tlie slowness with wliich the importance of his technique was recognised. This did not Iiowever discourage him and now the method is used so universally that it is difficult to remember that it took so long to become established. Before this pioneering development of atomic absorption Walsli was already known internationally for his ingenious multi-pass systems in spectral measurement allowing con- ventional monochromators to be used with increased resolving power and considerable reduction in scattered light. Considering the simplest case that of double-pass the method was to replace the conventional exit-slit of the rnonocliromator by two perpendicular mirrors so that the light returned through the monochromator and out through a suitably placed exit-slit.Recause of tlie double reflection the return pass added dispersion to that of the initial pass. A chopper interrupted the light between the mirrors and the signal was amplified by an amplifier tuned to the frequency of the chopper. ’l’his separated the twice-passed 155 It is sometimes referred to as the “f-value”.) 156 ATOMIC AAZSSOKPTION SPECTIWSCOPY CONIWENCE [ PYOC. SOC. Amdyt. Chew. signal from all other light including light scattered in the early stages. (This idea of separat- ing wanted a.c. from unwanted d.c. occurs again in Walsh’s atomic-absorption equipment in this case to separate the atomic line radiation from lmckground arising from the flame ernissi on. ) Another developrrient to which he has contributed is that of microwave-powered lamps and the application of them to the excitation of the Ranian effect. He is good company fond of cricket and enjoys being a Pornmie supporter among his Australian colleagues. He welcomes discussion and is patient and helpful to anyone with a problem in his field of knowledge. He was given the Kritannica Award in Science in 1966 and made President of the Australian Institute of Physics in 1967. He is a Fellow of the Institute of Physics and Physical Society a Fellow of the Australian Academy and this year was made a Fellow of the Royal Society.

ISSN:0037-9697    

DOI:10.1039/SA9690600155

出版商:RSC    

年代:1969

数据来源: RSC

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166 International Atomic Absorption Spectroscopy Conference Shef f ield 1969 ‘I‘m International Atomic Absorption Spectroscopy Conference which took place in the University of Sheffield during the week of July 14th to 18th 1969 was the first of its kind to be held in the United Kingdom and it is believed the largest so far in the world on this subject. About half of the 405 scientific delegates were from overseas and in all about thirty countries were represented-a truly international gathering. This international flavour was also very apparent in that about 60 per cent. of the contributed and plenary papers were presented by overseas speakers. Even the weather played its part for with bright sunshine and temperatures in the eighties it was certainly far from being “typically British.” (L-R) Pvofessov A .G. Quavvell Dv. ./. B. Dawson (Confevence Pvesident) and Dv. A . Walsh at the Univevsity Reception The official proceedings were opened by the Conference President Dr. J . B. Dawson who welcomed delegates on behalf of the Society for Analytical Chemistry and the Institute of Physics and the Physical Society. The Vice-Chancellor speaking for the University and the city of Sheffield also welcomed the delegates and hoped that they would have an enjoyable and successful Conference. The opening ceremony was concluded by the President of the Society for Analytical Chemistry Professor T. S. West who paid tribute to the pioneering work of Dr. A. Walsh F.K.S. before presenting him with the Certificate of Honorary Member- ship of the Society. Dr. Walsh was then invited to open the Scientific Programme by giving the first plenary lecture.September I 9691 157 On each of the 4 days allocated to the Scientific Programme the proceedings started with two plenary lectures in the Firth Hall of the old University followed by parallel sessions of contributed papers (nearly 60 in all) in the lecture theatres of the newly constructed Arts Tower. Visitors were able to compare for themselves the changing styles o f university architecture from the baronial splendour of the Firth Hall to the elegant simplicity of the Arts Tower. I’rom the 18th floor at the top of the tower delegates were able to enjoy superb views of the city of Slieffield. ATOM I C AH S 0 I< PTI ON SPE CTR OSCOPY CONFE KEN CE (L-R) Pvc?fessov K . V . I,’ Vov Pvofessov 7’. S. West and Pvofessov H .N . Robsoi? at the lJniue~saty Recejbttow The Scientific Programme was not rigidly confined to atomic-absorption spectroscopy but ranged over many aspects of the related topics of atomic-fluorescence spectroscopy and flame-emission spectroscopy. Delegates were able to choose between fundamental and applications papers which included reports on light sources flame and non-flame cells The Lovd Mayov avzd 1,ady Mayowss oj .She#ield Yecezving MY. and MYS. W . I?. Dijhema at the Ciuac Keceptiouz atomisation processes and instrumental developments. The continuing and widespread appeal of atomic-absorption spectroscopy and related techniques was amply demonstrated by the questions during the sessions and the many earnest discussions that took place both 158 ATOMIC ABSORPTIOS SPECTROSCOPY CONFERENCE [Proc.SOC. Analyt. Chenz. during the refreshment and lunch intervals and also the leisure periods in the evenings. One delegate was heard to remark that he was surprised how many people could sleep eat and drink atomic-absorption spectroscopy ! A further opportunity for airing views occurred on Friday afternoon when all the plenary lecturers “volunteered” to form a Brains’ Trust to answer delegates’ written questions. The stimulating and often controversial discussions that resulted were much appreciated by the audience. On Thursday and Friday a Manufacturers’ Exhibition was held in the Department of Chemistry. Some seventeen manufacturers of atomic-absorption spectroscopy equipment and accessories displayed their products. There were also exhibits from the Society for Analytical Chemistry and the Institute of Physics and the Physical Society.Many delegates took this opportunity for making on-the-spot comparisons of different instruments and equip- ment some cf which had only recently been brought on to the market. There was a full Social Programme during the week on which the seal of success a t least cf the “outdoor activities,” was set by the fine weather. On Monday evening the Vice- Chancellor Professor H. K. Robson on behalf of the University held a Sherry Reception in the Firth Hall. On Tuesday delegates and their wives spent a most enjoyable evening a t a Civic Reception and Supper held in the delightful grounds of the Weston Park; all guests were graciously received by the Lord Mayor Alderman D. J. O’Neill J.P. and the Lady Mayoress.The Scientific Programme on Wednesday was limited to a well attended evening meeting devoted to a discussion on future international meetings on atomic-absorption spectroscopy and terminology in atomic-absorption spectroscopy. During the day delegates took advanta5e of a variety of half-day and full-day tours to visit many of the interesting places within easy reach of Sheffield including Jodrell Bank the city of York and the world-famous Wedgwood Pottery Factory. On Thursday evening the Conference President returned the hospitality of the city and University by inviting the Senior Pro-Vice-Chancellor Professor D. N. de G. Allen (representing both city and University) to the Conference Banquet. Some 375 delegates and their wives attended the Banquet which was held in the Phoenix Rooms of Steel Peach and Tozer Ltd. (L-R) DY. A . Townshend Mr. R. A . W h i t e Mrs. E . W i l k i n s o n Dr. G. F. Kirkbright MYS. J . A . Crossley Dr. R. Dagnall MY. B. Bagshawe MY. P. C. W i l d y and MY. D. G. Swinburn at the reception befove the Conference Banquet During the week wives of delegates had their own Ladies’ Programme with visits which took them among other places to Chatsworth House and to Coventry Cathedral. The Organising Committee composed of members of the Atomic-Absorption Spectro- scopy Group of the Society for Analytical Chemistry and the Spectroscopy Group of the Institute of Physics was under the Chairmanship of Dr. J. B. Dawson (University of Leeds). All arrangements in Sheffield were made by the Local Committee whose Chairman was Mr. W. R. Nall (Chemical Inspectorate Ministry of Defence).

ISSN:0037-9697    

DOI:10.1039/SA9690600156

出版商:RSC    

年代:1969

数据来源: RSC

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September 19691 INTERNATIONAL SYMPOSIUM 159 International Symposium on Analytical Chemistry Birmingham 1969 THE University of Birmingham was the venue from July 21st to 25th 1969 of the Inter- national Symposium organised by the Midlands Section cf the Society for Analytical Chem- istry and held under the patronage of the International Union of Pure and Applied Chemistry. The Symposium President was Professor M. Stacey C.R.E. F.R.S. (Mason Professor and Head of the Department of Chemistry University of Birmingham) and the joint Honorary Presidents were Professor T. S. West (President of the Society for Analytical Chemistry) and Professor W. Kemula (President of The Analytical Chemistry Division I.U.P.A.C.). There were 585 delegates and guests from 30 nations. The Symposium Pvesident Pvofessov M.Stacey with Pvofessov T . S. West Pvofessov W . Kemula and MY. W . T . Elwell (Symposium Chaivman). Plenary Lectures which will be published in full in Pure and AppZied Chemistry I.U.P.A.C.’s official journal were delivered on the following topics- “Analytical Methods for the Study of Air Pollution,” by Professor Philip W. West of the Environmental Sciences Institute Coates Chemical Laboratories Louisiana State Univer- sity Baton Rouge La. U.S.A. “Analytical Applications of Stripping Processes in Voltammetry,” by Professor Wiktor Kemula of the Institute of Chemical Physics Polish Academy of Sciences Warsaw Poland. “The Analytical Chemistry of Mixed Ligand Complexes,” by Professor Ivan P. Alimarin of the Institute of Analytical Chemistry M. V. Lornonosov Moscow State University and the V.I. Vernadsky Institute of Geochemistry Russian Academy of Sciences Moscow U.S.S.R. “The Present Status of Electron Microprobe Analysis,” by Professor Hanns Malissa of the Institute of Analytical Chemistry Technical University of Vienna Austria. “The Present Status of Organic Microanalysis,” by Dr. Wolfgang Schoniger of the Microanalytical Laboratories Sandoz A.G. Basle Switzerland. “Forensic Science and the Analyst,” by Professor Cecil L. Wilson of the Chemistry Department Queen’s University Belfast Northern Ireland. The Scientific Programme included sessions on separation processes organic reagents polarography flame methods activation analysis electrochemical methods ion-selective electrodes chromatography thermal methods and organic analysis. Each session was headed by leading chemists in the particular field.In all 110 lectures were presented by speakers from 22 countries. An informal “Mixer” during Monday evening provided an opportunity for delegates and lecturers to meet. His Right Worshipful The There was a full Social Programme. 160 INTERNATIONAL SYMPOSIUM [Proc. SOC. Analyt. Chem. Lord Mayor of Birmingham held a Civic Reception at the Council House on Tuesday. Most of Wednesday was given over to tours of various industrial establishments and places of interest with visits to the Royal Shakespeare Theatre Stratford-upon-Avon or the Belgrade Theatre Coventry in the evening ; the afternoon tours from which delegates selected were the Worcester Royal Porcelain Co. Ltd. the Fruit and Vegetable Preservation Research Station Chipping Campden Hidcote Manor Gardens and Compton Wynyates House the Tyseley Factory of Bakelite Xylonite Ltd.The Witton Factory of Imperial Metal Industries Ltd. the Oldbury Factory of Messrs. Albright & Wilson Ltd. the Cape Hill Brewery of Messrs. Mitchells and Butler Ltd. the Aston Brewery of Messrs. Ansells Ltd. the Soho Foundary of Messrs. Averys Ltd. and the Bournville Works of Messrs. Cadbury Bros. Ltd. Pvofessov I . P. A limaviuz pveseuzts the Lomouzosov Medal to Professov Relcher On Thursday evening the Symposium Dinner was held in the University Refectory and the week ended with a Buffet Reception on Friday evening kindly provided jointly by local industry and the University of Birmingham. Pvofessov Belcher presents the Talanta Gold Medal to DY. A . Walsh September 19691 INTERNATIONAL SYMPOSIUM 161 The Ladies’ Programme included visits to the Barber Institute of Fine Arts the Birming- ham Assay Office Aston Hall and the Webb Corbett and Royal Brierley Glass Works Stourbridge and also tours to Coventry and Warwick and of the Cotswolds.Dv. A . A . Smales receiviwg the Hevesey Medal fyom Pvofessov L. Evdey During this year (on December 9th) Professor Belcher will celebrate his 60th birthday and the symposium was made the occasion for many presentations to commemorate that fact. Pvofessov apzd MYS. Helchev with fovmev and pvesent veseavch studewts attewding the Conference After the opening ceremony on Monday Professor I. P. Alimarin presented him with the Lomonosov Medal on behalf of the M. V. Lomonosov Moscow State University. During the first social event of the Symposium that same evening several presentations were made Professor H.Malissa of the Technical University of Vienna presented him with the Golden Eagle of the Austrian Microchemical Society; Professor H. Spitzy on behalf of the Austrian Society for Micro- and Analytical Chemistry presented him with a view of Graz about 300 years ago printed on silk; and Mr. Howard J. Francis presented a birthday cake from the American Microchemical Society (which was served to the delegates as the culmination of the social evening). 162 RADIOCHROMATOGRAPHIC ANALYSIS [Proc. SOC. Auzalyt. Chew. Before Tuesday's plenary lecture Professor R. P. Lastovsky presented Professor Belcher with the Mendeleev Medal from the D. I. Mendeleev All Union Chemical Society and on Friday the first plenary lecture was preceded by a presentation by Professor C.Duval on behalf of the French delegation to the Symposium of a silver Loving Cup. 'There were other less formal presentations to Professor Belcher at the Symposium Dinner the Symposium Chairman Mr. W. T. Elwell presented him with a Georgian silver teapot milk jug and sugar bowl on behalf of all delegates and during a lunch on Thursday Mr. G. F. Richards of Pergamon Press presented him with a specially bound copy of the Talavtta Honour Issue. At the Thursday lunch Pro- fessor Belcher presented the Talavtta Gold Medal to Dr. Alan Walsh whose election to Hon- orary Membership of our Society had been first publicly announced at the beginning of the Conference on Atomic Absorption Spectroscopy held by the Society in Sheffield the previous week and on the Tuesday Dr. A. A. Smales past-president of the Society was presented with the Hevesey Medal by Professor L. Erdey on behalf of the Jourrtzal of Radioanalytical Chemistry. There were other presentations during the Symposium.

ISSN:0037-9697    

DOI:10.1039/SA9690600159

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

162 RADIOCHROMATOGRAPHIC ANALYSIS [Proc. SOC. Auzalyt. Chew. Radiochromatographic Analysis The following are summaries of the papers presented at a Joint Meeting of the Chromato- graphy and Electrophoresis Group and the Radiochemical Methods Group held on February 27th 1969 and reported in the March issue of Proceedings (p. 35). The Use of Gas - Liquid and Thin-layer Radiochromatography in Studies on Lipid and Drug Metabolism BY P. JOHNSON AND H. R. HAZELTON (Wellcome Research Labovatovies Langley Court Beckenhavn Kent) RADIOCHROMATOGRAPHIC techniques are particularly useful in studies of drug and lipid metabolism in which very small amounts of metabolites must be separated identified and determined quantitatively often without the assistance of chemical methods. I n selecting apparatus for the measurement of chromatographically separated radioactive components the choice of counting system will depend not only on the type of isotope to be detected the efficiency of the counter for that isotope and the counter background but also on the particular needs of the operator and compatability of the counter with the chromatographic system.In detecting radioactive peaks from a gas - liquid chromatograph for example there is a primary choice between discontinuous off-line counting systems and continuous on-line flow-detection systems. Where one already has a suitable counter the former system will be cheap and adequate for some purposes. However apart from many advantages that could be grouped under the general heading of “Convenience,” it should be emphasised that the compelling reason for using a continuous-flow system is that it obviates the danger inherent in any discontinuous system that radioactive peaks of low mass which would not be recorded by a mass detector may be completely missed by off-line counting.In using a flow-detection system there are three further choices to trap the effluent peaks for example in liquid scintillator for continuous monitoring of the level of radioactivity (giving an integral output) ; to use a counter at the same temperature as the gas chromatograph such as a heated proportional counter; and to convert the effluent gases into permanent gases for counting at room temperature. I n leading effluent gases at elevated temperature from the gas chromatograph to the counter it is essential that no condensation occurs between the two systems and therefore some form of heated transfer line will be required.We have linked an F & M 5750 Research Gas Chromatograph via a heated transfer line to a Yerkin-Elmer - Berthold RGC 170 gas- flow proportional counter. The heated transfer line consists of a length of +-inch stainless- steel tubing bound with a Variac-controlled Electrothermal heating tape and outer asbestos September 19691 RADIOCHROMATOGRAPHIC ANALYSIS 163 cord. The Berthold system allows the choice of converting the effluent peaks into permanent gases either by the well known method of oxidative combustion or by the more novel method of hydrogenative cracking. Oxidative combustion of carbon-14 compounds is carried out by passing the gas-chromatograph effluent over copper oxide at 650°C and water is trapped out by the use of a magnesium perchlorate drying tube prior to the proportional counter.For tritium-labelled compounds the water can be reduced to hydrogen by using iron filings in the combustion furnace. Hydrogenative cracking is accomplished by using a mixture of metal oxides and a nickel catalyst at 500°C in the presence of hydrogen. The detection of com- ponents of a mixture of carbon-14 fatty acid methyl esters (separated gas chromatographically on DEGS columns) by the two methods shows a higher efficiency of radioactivity detection by oxidation than by hydrogenation. This can be explained in terms of the equation for over-all efficiency E of the system- E = k E 2 where k is a constant; E is the efficiency of the counter; v is the volume of the counter; and f t is the gas flow-rate.It is apparent that in using the hydrogenative cracking process the introduction of hydrogen with a necessary corresponding increase in the flow of methane quench gas to tke counter results in an increase in theft term of the equation and a corresponding fall in E . A similar loss of efficiency has been observed in the detection of carbon-14 labelled basic drugs separated gas chromatographically on OV 17 columns. However the option of hydrogenative cracking allows the use of an alternative method to oxidative combustion for the determination of tritium-labelled compounds and for materials that may be difficult to combust in oxygen. When a non-destructive gas-chromatographic detector is used the effluent gases can be transferred directly from the mass-detector block to the counting system.In our instrument we use flame ionisation detectors and a splitter must therefore be incorporated that will transfer only a small proportion of the effluent stream to the flame detector the bulk of the gases passing via the heated transfer line to the proportional counter. Under normal condi- tions of gas-chromatographic analysis a split ratio of 1 20 may be obtained by using a splitter of equal bore in both arms with lengths of coil in the ratio 20 1. However the back pressure created by the combustion system is such that it is necessary in our instrument to use splitter arms of bore b with length I and bore b/2 with length 60 x I in order to obtain a 20 1 split ratio when the combustion furnace is in use. The various methods of measuring radioactivity on thin-layer chromatograms fall into three main groups removal of zones autoradiography and automatic scanning; we routinely use a combination of the various types of method.The use of a Panax scanner (windowless Geiger - Muller counter) has proved particularly useful in our laboratory for the rapid evaluation of urinary metabolic patterns. Rats are dosed with labelled compounds and the urine collected from an all-glass metabolism cage with a urinary - faecal separator is chromatographed directly on silica gel G plates of 200 to 250 pm thickness as samples of less than 50 pl. Various solvent systems are used and patterns from normal urine are compared with drug-treated animal urine and the latter also treated with various conjugate breaking enzymes such as /I-glucurionidase for glucuronide identification.Labelled peaks down to about 1 inp Ci of carbon-14 and 10 mp Ci of tritium are revealed by the scanner and a rapid evaluation of major metabolites is obtained with nearly quantitative automatic print-out. Minor components are then detected by subsequent autoradiography followed by elution and counting or specific spraying as required. The use of scintillation sprays such as 1,4-bis(5-phenyloxazo1-2-yl) benzene (POPOP) in chloroform have proved particularly useful in some applications in which visual identification under ultraviolet light can be obtained without interference by the spray reagent with subsequent scintillation counting . Recent additions to the range of instruments for thin-layer scanning include the spark- chamber (Panax) and the p-Camera (Kaird-Atomic).The spark chamber emits a visible discharge on or near the path of a P-particle and by exposure to Polaroid film an “autoradio- graph” of low amounts of radioactivity can be obtained within minutes. Quantitative determination with this system is difficult. The p-Camera consists of 1622 windowless Geiger - Muller counter heads which cover the whole of a standard thin-layer plate and can be used to obtain quantitative information. ft 164 RADIOCHROMATOGRAPHIC ANALYSlS [PYOC. SOC. Anaht. Chem. In the field of lipid metabolism we are interested in the excretion of lipid by the liver fluke (Fasciola Hepatica L.) and have also studied the incorporation of labelled precursors such as glucose and acetate from media into the lipids of the fluke. Thin-layer chromato- graphy indicates similar patterns in both the lipids of the intact fluke and those excreted into an incubation medium.Such excretion can be reduced to one tenth by ligation of the oral and excretory openings of the fluke but the remaining excreted lipid retains the same over-all lipid pattern. This probably indicates leakage through the ligatures or a minor pathway of excretion through the body wall or inducement of such a pathway by ligation. Thin-layer radiochromatography has shown the incorporation of both 1- and 6-carbon-14 labelled glucose and 1- and 2-carbon-14 labelled acetate into a wide spectrum of fluke lipids. Gas radio- chromatography via oxidative combustion is being used to investigate the fatty acid patterns in the fluke lipids after incorporation of such labelled precursors.The Use of Thin-layer Chromatography in Checking the Purity of Labelled Compounds BY D. A. LAMBIE (Quality Covztvol Depavtment The Radiochemical Centve Amevsham Rucks.) THE concept of purity as applied to radioactively labelled compounds is more complex than that applied to inactive compounds. Resides chemical purity which has the same significance for both active and inactive compounds it is necessary to recognise radiochemical purity i.e. the proportion of the total activity present in the stated chemical form and radionuclidic purity i.e. the proportion of the total activity which is the activity of the stated radio- nuclide. This paper is concerned only with the determination of radiochemical purity of labelled compounds. A high degree of radiochemical purity is of importance for all uses of radio- chemicals as tracers and although it is the manufacturer’s aim to produce materials of ade- quate purity and to store them in such a way that decomposition is minimised some decrease in radiochemical purity with time is unavoidable.It is therefore important for all users as well as for manufacturers to be able to determine the purity so that allowance can be made for any change. The purity to be determined always approaches 100 per cent. (we are not concerned here with grossly impure material that is rejected). This simplification of the task is counter- balanced by the need to work with very small samples because of the smallness of the batches (milligrams or grams) and their consequent value and a desire to minimise radiological safety precautions.Before the advent of chromatographic methods reverse isotope-dilution analysis had to be used. This involves mixing a small weight of the labelled compound with a large weight of the pure inactive compound subjecting the mixture to a rigorous purification and deter- mining the specific activity of the purified mixture in comparison with that before purification. The drawback of the method is that as the purity approaches 100 per cent. the difference between the specific activities being compared becomes less than the accuracy of the rneasure- ment. It also calls for a high degree of manipulative skill on the part of the operator. It was perhaps fortunate that a revival of chromatographic methods of analysis took place about the time that the problem arose. Although reverse isotope-dilution analysis still has its applications paper partition and thin-layer chromatography are pre-eminently suitable for this work.If a labelled compound is subjected to thin-layer chromatography in several systems which are known to separate it from the possible active impurities and one active component only is detected the compound must be radiochemically pure. If also the R of the active component corresponds with that of a chromatogram of authentic inactive material run on the same plate the identity of the compound is confirmed. To operate such a system with absolute certainty requires that we know the identity of all possible impurities and have suitable chromatographic-separation procedures for them. We cannot claim such infallibility although over the years we have built up a considerable volume of experience and in cases of doubt it is always possible to make checks by reverse isotope-dilution analysis.September 19691 RADIOCHROMATOGRAPHIC ANALYSIS 165 There is no novelty in our methods of chromatography which are in line with the pub- lished recommendations but our methods of measurement and evaluation may be of interest. We have the advantage of the easy detection of separated constituents by virtue of their radioactivity. The simplest method autoradiography is not used quantitatively but merely as a means for locating active areas for removal from the plate and subsequent measurement by liquid scintillation counting. This is probably the most accurate method but the most expeditious method scanning with a suitable radioactivity measuring instru- ment is preferred for routine use at Amersham.Initially the absorbent layer was converted into strips that could be handled by spraying the plates with an aqueous suspension of Neaton [poly(vinyl propionate)] air drying and covering with strips of Scotch tape. The strips were then peeled off the plate and scanned in the apparatus which had been developed in our Physics Department for scanning paper chromatograms. The essential part of the scanner was a windowless proportional methane - argon flow counter. The strip was drawn by the same mechanism as that which operated the recorder beneath the counter. Although the apparatus worked well the method involved the delay required for plasticis- ing the film so a further piece of apparatus was developed by our Physics Department for direct scanning of the chromatographic plates.This involved a mechanism to traverse the plates in a gas-tight metal box so that the chromatograms passed below a windowless flow counter similar to that used in the paper-strip scanner. The scanner can be used with any of the nuclides used for labelling at the Centre including tritium. If the compound is radiochemically pure the chromatographic record will show one peak only and there will be no problem of interpretation. If however there is more than one peak it is necessary to measure the area bounded by each peak which is proportional to the activity of each fraction. Various methods have been used for this use of a planimeter; cutting up the chart and weighing; triangulation; and the use of a disc integrator. Of these the method of triangulation and the use of the disc integrator are preferred.Low Background Systems for Radiochromatography BY T. H. SIMPSON ( Mavine Laboratory Department of Agricultuve and Fishevies f o r Scotland A bevdeen) RADIOSCANNING of developed chromatograms or of the effluent streams from liquid or gas chromatograms can be treated as a special case of a generalised flow-counting procedure in which radioactive material of activity N disintegrations minute-l located at a particular point on the chromatogram is made available to the radiodetector for a time t the counter residence time which is given by the expression- where x is the counter aperture or volume and z is the scan spread or effluent flow-rate. As the confidence with which the counts accuinulated by the scanner fall within the defined limits & d per cent.of the true value is given by the expression- where K is the confidence constant E is the counting efficiency and B is the background count-rate it follows that the sensitivity of the scanning procedure is critically dependent on the choice of scanning parameters x and z, and on the use of detectors of high intrinsic efficiency and low background. In practice z tends to be fixed by the requirements of work throughput and by the characteristics of the chromatograph while the choice for an appropriate value of x involves a compromise between the conflicting needs for high fidelity in reproducing the profiles of activity on the chromatogram (x -+ 0) and high detection sensitivity (x -+ peak width or volume).l In this laboratory the values of peak width x are chosen to lie between 10 and 2 depending on whether the requirement of fidelity or sensitivity is paramount.166 RADIOCHROMATOGRAPHIC ANALYSIS [Proc. SOC. Avzalyt. Chem. Flow detectors for p- and y-emitters in liquid effluent streams are now commonplace.2 Tritium and carbon-14 labelled materials are perhaps best located by an anthracene-packed cell mounted jn a polymethylmethacrylate light guide and viewed by two photomultipliers operating in coincidence. Typical efficiencies for a flow cell packed with anthracene crystals 150 pm in size are 2 and 55 per cent. for tritium and carbon-14 respectively. Detection of y-emitting material is best achieved by a conventional assembly of well-type thallium- activated sodium iodide crystal and photomultiplier.The flow cell which is inserted into the well and may be enclosed in a can of 0.008 inch aluminium or of plastic is formed from a helix of YTFE tubing of appropriate dimension. By using more than one pulse height analyser which should be adjusted to maxiniise E and minimise cross-over from the lower to the higher energy channel simultaneous scanning of two or more isotopes e.g. iodine-125 and 131 is possible. In all quantitative scanning of liquid chromatograms maintenance of constant flow-rates usually by means of a peristaltic pump is imperative. Scanning of high energy y-emitters on thin-layer or paper chromatograms presents some difficulties as the need for a sufficient thickness of lead to ensure enough collimation to give the required resolution involves the acceptance of low counting efficiencies.Isotopes such as iodine-131 that emit both ,El- and y-particles are best located on chromatograms by scanning the P-particle component. In contrast low energy y-emitting nuclides on chromatograms can be scanned by a simple assembly of photomultiplier and thin thallium-activated sodium iodide crystal. By using such a crystal in a steeply collimated end-cap iodine-125 labelled thyronines on thin-layer chromatograms are scanned in this laboratory3 at an efficiency of 50 per cent. and with a background count-rate of less than 4 c.p.m. Detection of P-emitting nuclides on paper or thin-layer chromatograms is best accom- plished by the use of scanners with gas-flow and Geiger - Muller detectors operating in 4rr and 2rr configuration respectively. Several forms of this apparatus are commercially available.All these detectors operate at efficiencies approaching 100 per cent. for incident ,&particles (less than 0-155 MeV). The high net counting efficiencies for some thin-layer scanners are achieved at the expense of lowered resolutions. By incorporating a small cosmic shield formed from a disc type Geiger - Muller counter and operating in anti-coincidence with the chromatogram detectors we have succeeded in lowering the background count-rates of paper and thin-layer scanners to less than 4 c.p.m. and less than 1 c.p.m. respectively; the difficulty in maintaining the detectors completely free from contamination under normal laboratory conditions makes it far from easy in practice to realise the advantages conferred by using cosmic guards with their attendant complications.Gas-flow proportional counters are the detectors of choice for counting P-emitting nuclides in the effluent stream of a gas chromat~graph.~p~?~ The disadvantages associated with these detectors of high background count-rates (greater than 25 c.p.m.) have recently been overcome by the use of a plastic scintillator cosmic guard counter operating in a y-shield of graded construction.7 The counter which has a volume of 14 ml shows efficiencies for carbon-14 and tritium of greater than 95 per cent. and greater than 60 per cent. respectively and has a background count-rate of about 1 c.p.m. Data from radiochromatogram scanning equipments are commonly displayed by a rate- meter and chart recorder; this form of presentation although attractively direct has certain limitations.When quantitative information is desired particular care must be taken to select ratemeter time constants that neither distort the fidelity of reproduction of chromato- gram profiles nor force the operator into making a personal judgment on the areas of activity which must then be determined by the laborious procedures of planimetry or “cut and weigh.” The benefits of low background scanning procedures are best realised by using a scaler - timer and fast parallel printer to record digital information to supplement the rate-meter analogue display. REFERENCES 1. 2. 3. 4. 5 . 6. 7. Johnson M. J. J. Chvomat. 1965 20 100. Rapkin E. Lab. Scintzllatov 1967 11 1. Oshorn R. H. and Simpson T. H. J. Chvomat. 1968 35 436. James A. T. in James A. T. and Morris L. J . Editovs “New Biochemical Separations,” Van James A. T. and Piper E. A. J. Chvomat. 1961 5 265. James A. T. and Hitchcock C. Kevntechnzk 1963 1 5. Simpson T. €I. J. Chvomat. 1968 38 24. Nostrand London 1964.

ISSN:0037-9697    

DOI:10.1039/SA9690600162

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

September 19691 PARTICLE-SIZE ANALYSIS 167 Inertial Methods of Particle-size Analysis The following are summaries of two of the papers presented at a Joint Meeting of the North of England Section and Particle Size Analysis Group on March 5th 1969 and reported in the April issue of Proceedings (p. 55). Summaries of the other two papers presented at this Meeting appeared in the June issue of Proceedings (p. 96). Particle-size Analysis with the Sharples Super Centrifuge BY J. A. M. MCLEAN THE conditions for using the Sharples Super Centrifuge a standard laboratory tool for particle- size analysis were defined as follows. (Pennsalt Ltd. Pvocess Systems Division Doman Road Carnbevley Suvvey) (i) Particles should be in the range 100 pm to 0.05 pm. (ii) Particles should be of uniform specific gravity and denser than the suspension medium.(iii) Liquid suspension medium that is inert towards the particles physically and chemi- cally should be available. (iv) The suspension medium should be readily removable from the collected particles to facilitate gravimetric analysis. To ensure that meaningful results are obtained the following factors should also be considered. 1. Physical effects such as wall effects and convection currents and the necessity for correction of factors such as Corilis factor should be eliminated by suitable choice of equip- ment. 2. Hindered settling should be avoided by using large samples of dilute suspensions. Concentrations of not greater than 0.05 per cent. w/w have been suggested.l 3. Effective dispersion of the particles must be ensured by using dispersants or anti- flocculants vigorous stirring even to the possible use of ultrasonics and in certain cases by pH control.4. Reproducibility is often of greater importance than absolute values for routine testing. 5. The end use of the analysis should always be considered. Each technique measures a different “size” unless perfect spheres are used. Centrifugal sedimentation considered here measures the “equivalent Stokes’ diameter” and is thus of use when knowledge of the particle size is needed for some physical flow system. The particles should be roughly spheroidal and not in plate or needle form. Flow through the system should be streamline. For errors of not greater than 5 per cent. when using Stokes’ Law the Reynolds number ( R e ) should not exceed 0-2. At low values of R e the particles will be randomly orientated but at higher values there will be a tendency to re-orientate and the lowest values of Stokes’ diameter will be measured.2 Thus agglomorates will tend to be broken.In the powder form agglomerates may form a significant fraction of the whole and thus centrifugal analysis could give erroneous results unless checked by microscope. Centrifugal sedimentation techniques were disc~ssed,~ and listed as follows Incremental methods- (i) Disc centrifuge (ii) Centrifugal photosedimentome ter This can only be checked by repeated runs on the same material. 6. 7. 8. High shear forces exist on entry to a centrifuge. Cumulative methods- (i) Beaker centrifuge (ii) Whitby column (iii) Sharples Super Centrifuge 168 PARTICLE-SIZE ANALYSIS [Proc. SOC.Aaalyt. Cheuvt. It is therefore possible to use dilute suspensions and collect sufficient material for accurate gravimetric analysis by passing a large volume. This is a well known standard laboratory tool available in turbine-drive form to operate at 50,000 r.p.m. giving a maximum of 62,00Og or with electric drive to give a maximum of 13,000 g. Several procedures have been reported for use with this instrument notably by Brown,4 H a u ~ e r ~ ~ ~ Saunders7 and The methods proposed and used by the first three workers begin with polydisperse systems and involve the use of successive fractionation and re-dispersion of each fraction which then allows theoretical treatment of each fraction as a monodisperse system. They also assume a constant volume of liquid in the centrifuge bowl.Bradley suggests the use of a varying sedimentation height by using a different centrifuge bowl type. When using a fixed height successive fractions can only be obtained by varying the feed rate and the centrifuge speed. This can be time consuming in determining these parameters at each analysis. By varying the sedimentation height the feed and speed settings on the machine can be fixed over a number of determinations thus simplifying the technique. To summarise techniques are available for the use of the Sharples Super Centrifuge as a method of particle-size analysis. These are most useful in the range in which other methods are unreliable. Provided care is taken in using the techniques reproducible results can be obtained. The techniques in which the Super Centrifuge is used involve flow systems.The Super Centrifuge was described. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. Scarlett B. Chem. Process Engng 1965 46 197. Davies C. N. Nutwe 1964 201 and 905. Particle Size Analysis Sub-Committee Analyst 1963 88 156. Brown C. J . Phys. Chew. 1944 48 246. Hauser E. A. and Lynn J. E. I n d . Eng.Yzg Chem. 1940 32 659. Hauser E. A. and Sehachman H. K. J . Phys. Chem. 1940,44 584. Saunders E. Analyt. Chew. 1948 20 379. Bradley D. Chew. Pyocess Engng Nov/Dec 1962. The Warman Cyclosizer for Particle-size Analysis BY C. R. G. TREASURE ( Welwyn Hall Reseuvch Association The Hall Chuvch Stveet Welwyn Hevts.) THE Warman Cyclosizer is a hydraulic elutriator in which the process of elutriation is speeded up by the use of centrifugal force. This is accomplished by using the hydrocyclone which is a simple cylindro - conical piece of apparatus.When a dilute suspension is injected tangent- ially into the hydrocyclone a strong vortex flow is set up in which size separation occurs through the opposition of centrifugal force and drag due to the inwardly flowing liquid. The fine fraction of the powder is carried with the bulk of the liquid through the axial vortex finder (overflow) and the coarse fraction passes out through the apex orifice (underflow). The coarse fraction contains a fraction of the feed material equal to the liquid fraction in the under- flow and is therefore never free of the finer sizes. Rased on the work of Kelsall and McAdaml the hydrocyclones used in the Warman Cyclosizer are fitted with apex pots. Internal re-circulation of the underflow fraction then occurs and repeated passage through the classifying zone results in the finer particles being expelled through the vortex finder.As a result the usual S-shaped classification curve indicating the probability of a given particle being discharged with one or other of the two product streams approaches more closely to the ideal vertical line as a function of time. The separation size which has equal probability of discharge with either fraction increases and in consequence the limiting particle separation sizes obtained in the cyclones lie in the range 50 to 1Opm. Each instrument is calibrated by the maufacturers to determine the ultimate separation size of each cyclone. For any particular test correction factors to determine the effective separation sizes are derived from a series of graphs based on flow-rate temperature powder density and elutriating time.September 19691 PARTICLE-SIZE ANALYSIS 169 The Cyclosizer equipment is a self-contained unit which includes a mains-fed supply tank pump flow meter and pressure gauge to provide and regulate the water flow. The sample-injection system consists of an inverted pot containing a suspension of the powder sample through which part of the main water flow can be diverted to extract the sample. Size fractionation is carried out in five similar hydrocyclones connected in series the overflow from one cyclone forming the feed to the next. The final overflow is generally passed to waste. The cyclones are operated in an inverted position to prevent settling of coarse particles in the pots and entrainment of fine particles.To obtain a different separation size in each cyclone the feed inlets and vortex finders of successive cyclones are of smaller diameter. To carry out a test water is pumped through the system at maximum flow-rate the air- core removed from each cyclone by momentarily opening the valve of each apex pot and the sample about 70 g bled slowly into the water stream by carefully opening the sample-con- tainer valve. The flow-rate is then reduced to the required value and held for a specified time. To recover the samples from the cyclones the flow-rate is again increased and each cyclone discharged through the apex chamber valve into separate beakers. The solids are then recovered by filtration and are dried and weighed. The weight of material passing to waste is determined by difference.Size analyses carried out with four materials ranging in density from 2.25 to 3.26 g ml-l gave results between those obtained by fixed-depth pipette sedimentation and by a Rostock Sedimentation Balance the agreement with the pipette results being generally good. Because of the re-cycling occurring in the cyclones sharp separations are expected. However analyses of the individual cyclone products show a size range that in every case extends well outside the calculated size limits. Only about half of each product lies within the expected size range the bulk of the remainder exceeding the upper size limit. When many size analyses covering the range 50 to 10 ,urn with 5 points are required the instrument can be very useful the total time for production of the fractions being about 1 hour. A relatively large feed sample is used and the fractions can be recovered for sub- sequent examination although the size limits are greater than those expected and considerable overlap occurs between successive fractions. REFERENCE 1. Kelsall D. F. and McAdam J. C. H. Trans. Insdn Chem. Euzgrs 1963 41 84.

ISSN:0037-9697    

DOI:10.1039/SA9690600167

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

September 19691 PARTICLE-SIZE ANALYSIS 169 Why Particle-size Analysis? The following are summaries of some of the papers presented at an Ordinary Meeting of the Particle Size Analysis Group held on May 7th 1969 and reported in the June issue of Pro- ceedings (p. 96). Particle-size Aspects of Cement Technology BY R. G. BLEZARD (Reseavch and DevelopYnent Tunnel Cemem! Ltd. West Thuvvock Essex) CEMENT technology is intimately concerned with the production and control of fine particulate matter destined to be a reactant of a later controlled hydration reaction. Portland cement is defined as a material that is manufactured by intimately mixing together controlled propor- tions of calcareous and argillaceous components burning them at a clinkering temperature and grinding the resultant clinker with gypsum to produce a cement that complies with the current British Standard (B.S.12 1958). The burning process occurs in long rotary kilns and is essentially a synthesis of specific calcium compounds in the CaO - SO, CaO - A1203 and CaO - Al,03 - Fe,03 systems under controlled conditions. Four phases predominate among the final calcined mineral assemblage vix 3Ca0.Si02 2Ca0.Si02 3Ca0.Al2O3 and a ferrite phase approximating to 4Ca0 .A1,03.Fe,03. These compounds can be identified by X-ray diffraction and microscopic techniques. The hydration of these cement compounds in a cement - aggregate - water system gives rise to the ultimate product which is concrete. Each compound in the mineral assemblage exerts its presence physically in an additive 170 WHY PARTICLE-SIZE ANALYSIS ? [Proc.SOC. Analyt. Chew. manner and the character of each compound on hydration is specific. Gypsum is added as a hydration retarder for 3CaO.A1,0,. A proper size distribution of the prepared raw material that comprises the kiln feed has an important influence on the efficient synthesis of minerals in the kiln process. The rate of the hydration reaction of cement minerals is a function of the compound assemblage in the presence of gypsum; and the particle-size distribution. Mihile the first factor covers the fundamental reaction components the particle-size distribution can influence the dynamics of the hydration i.e. the gelling and hardening. The grinding process is accomplished by tube mills and the grading nature of all cements is essentially of the same pattern and follows the Rosin and Rammler law- R = 100 exp.($)" where R is the residue i.e. 100-y; X is the particle size withy the proportion passing; X is the absolute size constant; and n is the distribution constant. This expression can be trans- formed to a linear form- log log __ = PZ (log X - log 27) + log (log e) [ ( 3 1 = n log x + c. The Rosin and Rammler law applies in general to the range 5 to 5Opm and as the law is not truly applicable in the lower size range (which contributes most to the specific surface) a purely mathematical approach is not acceptable for surface calculation. How does this deviation occur? Cement clinker minerals are ground with gypsum. Cement clinker is composed of several minerals of differing grindability gypsum is relatively soft. This is therefore a complex multi-component grinding system.A further complication is the removal of a percentage of fine particles in the milling by the passage of an air stream required for ventilation removing dust and for cooling purposes. Portland cement is therefore a complex mixture of compounds with a yolydispersive distribution tending to a general grading pattern and for strict control of the product behav- iour one must appreciate particle-size analysis. From the size-analysis aspect the main involvement is the effect on the rate of reaction and strength development of the gel but this aspect must be considered associated with the mineral distribution. 99.5 - 99 95 - 90 - - . 80 - 70 - U 60 - - 50 - 60 - 70 .- 80 - 90 - 95 - 98 36.8 J aJ L al a e- 4- -I 99 0.5 ' I I I I 1 J 99.5 I 2 5 10 20 50 100 200 Diameter urn Fig.1. Grading of an ordinary Portland cement on a Bennett diagram (based on Rosin and Rammler's law) September 19691 WHY PARTICLE-SIZE ANALYSIS ? 171 To appreciate fully the value of particle-size studies it is necessary that the test procedures are realistic. Cement particle-size distribution can range from just over 100 pm down to a fraction of 1 pm and many test procedures give only a limited size definition by quoting one value e.g. residues or specific surface. Soft minerals e.g. gypsum will accumulate in the finer fraction and likewise there will be a small variation of the proportion of the cement minerals in the various fractions; some workers suggest there is relatively more 3CaO.Si0 in the finer size fractions. But considering a graded size interval chart with respect to the surface area contribution the largest surface contribution will come from material finer than 2 pm.Regarding testing techniques sieving sedimentation air elutriation air permeability and electrical methods are used in the size analysis of cement. The methods are not all reconcilable but are essentially relative from the value of the data obtained from them. Prior to 1947 the cement industry influenced by B.S. 12 considered sieving to be the main fineness parameter with a maximum level for 89 pm (170 R.S. Sieve). Manual sieving is slow tedious and dependent upon particle shape. Air elutria- tors such as the F. L. Smidth flourmeter involves the up-blast technique based on the Mainz Petersen pattern. This instrument has a variable setting but is generally arranged to draw off “flour” finer than 22-5 pm and is calibrated against standard inert fluorspar.Air permeability systems related to the Lea and Nurse technique are now advocated by the current British Standard (B.S. 12 1958) which quotes minimum values only for the specific surf ace ; ordinary Portland cement (2250 cm2 g-l) and rapid hardening Portland cement (3250 cm2 g-l). The Lea and Nurse technique is not rugged enough for routine work and the basic Kozeny - Carmen expression is not wholly applicable to material below 10 pm. Thus derived adaptations of the basic Lea and Nurse system (by Rigdan Blaine etc.) are essentially relative and more amenable to routine study. It must be appreciated that permeability under set conditions is measured and specific surface is a derived function.Specific surface can often be misleading as a guide to cementing value because of the accumulation of soft material which may not hydrate. Attempts to automate air permeability techniques have resulted in only limited success e.g. Papadakis and Venuat (France 1964) and Temlik and Vitovsky (Czechoslovakia 1965). The Andreasen pipette sedimentation technique allows an assessment of the particle-size distribution but suffers from the disadvantage of its slowness. One particle-size distribution technique that has great promise but is not yet fully appreciated in the industry is the Coulter Counter. This is an electrical technique that enables the number and size of particles to be determined by suspending them in a non-reactive electro- lyte and causes the particles to pass through a small orifice on either side of which an elec- trode is immersed.The changes in resistance as particles pass through the orifice generate voltage pulses the amplitudes of which are relatively proportional to the volume of the particles. The pulses are amplified sized and counted and the size distribution determined from the derived data. There are only a few references made in the literature to cement app1ications.l 2 9 3 Although Portland cement is a complicated mixture of compounds the hydrates initially form an even more complicated mixture of compounds. The surface area of pastes and hardened gels must of necessity entail different techniques gas absorption methods based on the B.E.T. techniques are utilised. Such methods allow an assessment of the total surface as distinct from the external surface area given by permeability techniques.Elutriation techniques are probably more commonly used than is realised. REFERENCES 1. 2. 3. Brown 0. E. Cem. Lime Gvavel 1962 37 99. Eckhoff R. K. and Soelberg P. Betongtekniske Publihasjoner 1967 7 1. Yring I<. W. and Blezard K. G. in “Proceedings of the Coulter Users Conference,” 1968 p. 31; 1Winevals Processing 1069 10 16. Yarticle-size Analysis in Powder Metallurgy BY V. T. MORGAN (Bound Brook Ltd. Tvent Valley Road Lichfield Staffs.) THE different branches of the powder metallurgy industry have different reasons for measuring the size distribution of the metal powders they use but in general they all relate to the effect of different powder particle-size distributions on the quality of the end product. In most 172 WHY PARTICLE-SIZE ANALYSIS ? [Proc.SOC. Analyt. Chewz. cases an absolute size measurement is not required instead the analysis is aimed at maintain- ing a consistent end product. The object therefore is to ensure that today’s powder is the same as yesterday’s. The range of sizes is very large from 1000 pm to less than 0.1 pm and each metal powder (as well as each intended use for that powder) presents its own peculiar problem. The tech- niques used for size analysis have been developed to give “sufficient information” at the minimum cost and in the shortest time. Most of the metal powders used by the powder metallurgy industry are subjected to a sintering operation and one of the reasons for controlling the particle size is the effect of particle size on the sintering operation.With the exception of a few noble metals the surface of all metal powder particles is covered with an adherent film of oxide and similar adsorbed metal compounds. These films prevent the particles from welding together at room temperature and are thus responsible for the free-flowing properties of the powder. During sintering these films are removed by heating in a reducing atmosphere. Once the films are removed an inter-particle weld is initiated and this grows in area automatically as the system tends towards minimum surface energy. The growth rate of the inter-particle weld (by the movement of metal atoms) is clearly a function of the particle size or the distance the material has to move the smaller the particle size the faster the rate. However there is a limit to the advantages of fine powders by the increasing amount of oxide and other surface films all of which have to be removed before sintering can commence.Finer powders have a higher percentage by weight of oxides. They also have smaller pores which slow down the rate of permeation of the reducing atmosphere into the pores. They also slow down the rate at which the gaseous products of the reduction reaction can permeate from the pores. Many small inter-particle welds grow rapidly once the powder surfaces are stripped of their interfer- ing films but with thick sections this may take a long time. A smaller number of large inter- particle welds grows more slowly but the initiation of the sintering process at welds which are deep in the body of the porous compact can occur more quickly. Some powder metallurgy products seek a monosized powder e.g.for porous metal filters while for porous metal bearings and structural parts such as gears and cams a polysized powder is preferred for maximum strength and minimum costs. When an alloy is produced by the sintering of elemental powders it is usual for the minor element to have a smaller particle size than the major element. For example the tin powder in a 10 per cent. tin bronze would have a finer particle size than the copper powder. This is to reduce the diffusion time of the tin into the copper by giving more sites from which the diffusion can occur. However if the minor element is considerably finer than the major element there is a real risk of segregation occurring by a process of self sieving. Thus with powder blends it is the relative relationships between the particle-size distribution of the various ingredients that are important rather than the absolute size of any one of them.With monosized particles segregation is most likely to occur and hence pre-alloyed powders are invariably used. Particle shape is another factor that the powder metallurgist considers when discussing particle size. When the powder is intended for pressing into a compact before sintering the inter-particle weld is initiated by the seizure of particles as they slide over each other during the pressing operation. The magnitude of this inter-particle sliding and seizure determines the strength of the compact for a given porosity. With uniform spherical particles there is little or no sliding as the deformation produces only a flattening of the spherical surfaces.With polysized irregular particles considerable inter-particle sliding occurs. However the results of most methods of particle-size analysis are sensitive to particle shape hence the powder metallurgist has the additional problem of controlling shape or average shape before the results of a particle-size analysis can be properly interpreted. With metal powders intended for porous articles of controlled permeability the perme- ability method of controlling size is of interest. With metal powders intended for use as a catalyst the nitrogen absorption method is generally used. Hence the particle size of metal powders intended for sintering is a compromise. September 19691 WHY PARTICLE-SIZE ANALYSIS ? 173 In general because metals have a high specific gravity sedimentation methods are particularly effective at sizes below 50 to 100 pm; above 100 pm sieves are usually used.There are many specialised cases in which particle size is of particular importance such as microfine iron powders for permanent magnets where the ideal size is one magnetic domain; fine grained carbide where the particle size influences the metallurgical grain size; and sintered aluminium powder where the oxide skin forms a disperse phase for strengthening at high temperature. Thus in answering the question “Why particle-size analysis in powder metallurgy?” we find that in both the general and the specific cases particle-size analysis is a powerful weapon in controlling the quality of the end product. The Importance of Particle-size Analysis in Studies on the Rheological Properties of Emulsions BY 9.SHERMAN ( UniZevev Reseavch CoZwovth/ Welwyvz The Fvythe Welwyn Hevts.) THE rheological properties of emulsions whether determined at high or low rates of shear are influenced by several factors including the volume fraction of dispersed phase (#) the viscosity of the continuous phase (yo) the particle-size distribution and the viscosity of the dispersed phase when the particles are large and the interfacially adsorbed emulsifier film is fluid. When all other factors are kept at a steady level and only the particle-size distribution is altered for example by repeated homogenisation the magnitude of the rheological properties increases as the mean particle size decreases and the particle-size distribution narrows. The effect is particularly marked in emulsions that contain significant numbers of particles that are below 1 pm in diameter.It is important that this size effect be recognised otherwise incorrect deductions may be made about the effects due to the other factors. A simple example serves to illustrate this point. Suppose that we are studying the influence of # on emulsion viscosity ( T ~ - - ~ ) at a high rate of shear. The viscosities of a range of samples with different # values would be measured at this rate of shear in one of the several viscometers that are available commer- cially or can be constructed. All of these emulsions are prepared by the same prelim- inary mixing technique and with identical homogenisation conditions. The differences between sample viscosities are noted and lead to certain conclusions about the influence of + on yu + co.With a manually operated homogeniser or when using a pressure homogeniser at a constant not too high pressure the particle-size distribution (and the mean particle size) increases as # increases. Consequently yy jco values are affected simultaneously by two variables instead of only the one that we are studying. For a monodisperse suspension of non-flocculated non-deforming spherical particles its viscosity y if Newtonian or yy j m if the flow is non-Newtonian can be represented by The problem associated with size-distribution effects is difficult. where k the hydrodynamic interaction factor is inversely related to the particle size D. A qualitative relationship between k and D which has proved valid down to particle sizes as small as 0.05 pm is It can be shown that for a continuous size distribution with i size fractions equation (1) becomes ki = 1.079 + exp (O.OlOOS/Di) + exp (0.00290/Di2) .. . . .. . . ( 2 ) . where - - i and k, k, - Thus the size distribution has to be determined accurately so that its contribution to emulsion viscosity can be allowed for prior to assessing the contributions due to other factors. +, - - - #I represent the volume fractions of size fractions 1 2 ki are their associated hydrodynamic interaction constants. 174 WHY PARTICLE-SIZE ANALYSIS? [Proc. SOC. Autalyt. Chem. Rheological measurements at very low rates of shear e.g. creep compliance - time studies at a constant low shearing stress are also influenced by the particle-size distribution. For example it can be shown that the instantaneous elastic modulus is proportional to (mean particle size)-3.A more applied example for which a knowledge of particle-size data is important is the sensory assessment of the viscosity of emulsion-based foods by the consumer. It has been suggested that sensory response in the mouth depends on the stress that is manifested at a rate of shear of about 50 s-l. Presumably this stress is developed within a flocculated particle system which has only partially broken down under the shearing force developed by the masticatory mechanism. The degree to which the food structure breaks down under the influence of shear depends on the packing geometry of the particles and also on the attraction forces within the flocculated network. Both factors depend in turn on the particle-size distribution within the sample.REFERENCE 1. Wood F. “Kheology and Texture of Foodstuffs,” S.C.I. Monograph No. 27 1967. The Importance of Particle Size in the Pharmaceutical Industry BY N. A. ARMSTRONG (Welsh School of Phavmacy Univevsity of Wales Institute o f Science avzd Techuzology Cavdiff) UNTIL comparatively recently the criterion of a dose of a drug was the weight of drug present physical factors and the mode of presentation being ignored. However it is now realised that in certain cases physico-chemical properties may exert a profound influence on the thera- peutic efficiency of a drug and particle size is one of the more important of these factors. ORAL DOSAGE FORMS- As absorption is with few exceptions a passive process controlled by the concentration gradient across the drug wall the higher the dissolution rate of the drug the quicker it will be absorbed.Also if the dissolution rate is less than the absorption rate the former is the rate-limiting step of the over-all absorption process and will thus control the clinical response. The dissolution rate of sparingly soluble substances can be expressed by the Noyes - Whitneyl equation where d A / d t is the dissolution rate K the dissolution-rate constant; S the surface area cs the concentration of a saturated solution of the substance and c the concentration at time t. Thus dissolution rate is proportional to surface area and decrease in particle size should result in an increase in dissolution rate. Atkinson Bedford Child and Tomich2 found a direct relationship between the logarithm of the specific surface of the antifungal agent griseofulvin and its absorbability and by using drug particles of less than 5 pm were able to reduce the dosage regimen (and hence cost) to one half of its former value.Similar studies have been carried out on a number of other medicinal compounds for example sulphaf~razole,~ medroxyprogesterone and spironolac- Although the scientific literature is confused on this point it appears that if the aqueous solubility of a drug is less than 1 to 2 mg ml-l a study of absorption rate and particle size may be worthwhile. Because of increased absorption potential toxity hazards are increased as in the case of colloidal sulphur.6 Furthermore in the case of compounds that have a local effect on the lumen of the gut such as anthelmintics a compromise must be reached between increased absorption by the parasite and increased absorption by the host.Absorption from the gut usually takes place after the drug has dissolved. d A / d t = KS(C,-C) Reduction in particle size may however cause undesirable effects. September 19691 WHY PARTICLE-SIZE ANALYSIS? 175 INHALATION THERAPY- Administration of drugs by aerosol is now well established both for local treatment of the lung and for systemic effects. The latter is a particularly attractive prospect as if a drug particle can be placed on the surface of the alveolar membrane it will be rapidly absorbed. To reach the alveolar membrane however the particle must negotiate a series of air passages of progressively decreasing diameter at the same time resisting the effects of expiration.Thus to reach a desired site in the lung and hence to exert a reproducible effect careful con- trol of the particle size of the drug is required. For example to be absorbed from the alveolar membrane a particle size of between 0.5 and 2 pm is required although this range may be affected by depth of breathing and the presence of physiological abnormalities. Furthermore due to agglomeration in the moist environment of the lung the size of the drug particles may change during inhalation. MISCELLANEOUS ASPECTS- The speed of action of drugs administered or injectable suspensions or by topical applica- tion may be affected by particle size due to variations in dissolution rate. While the reduction in particle size may increase the therapeutic effect of a drug problems of powder flow may occur and a compromise between therapeutic effect and ease of handling must be made.REFERENCES 1. 2. 3. 4. 5. 6. Noyes A. A. and Whitney W. R. J . Amev. Chem. Soc. 1897 19 930. Atkinson K. M. Bedford C. Child K. J. and Tomich E. G. Antibiotics Chemolhev. 1962 12 232. Fincher J. H. Adams J . G. and Beal €1. M. J. Phavm. Sci. 1965 54 704. Smith D. L. Pulliam A. L. and Forist A. A. Ibid. 1966 55 398. Bauer G. Kieckmann P. and Schaumann W. Arzneimittel-Fovsch. 1962 12 487. Lees K. A. J . Pharm. Phavmac. 1963 15 43T. Particle-size Analysis of Pigments BY V. T. CROWL (Paixt Reseavch Station Teddiitgton Middlesex) DR. CROWL said that the particle-size distribution of pigments was related to many techno- logical properties such as opacity colour and the rheological behaviour of dispersions.However the particle-size distribution should be measured under conditions resembling those of the end use of the pigment. Electron microscopy was used because of the size range involved and the pigments were generally examined after dispersion in a viscous medium e.g. 15-poise linseed stand oil. Surface-area measurements were made by the BET nitrogen adsortion method but it was necessary to use a shape factor to obtain agreement with average particle diameters calculated from size distributions. These shape factors vary widely depending upon the degree of agglomeration of the pigments. Dr. Crow1 gave several examples of how the optical properties of pigments were dependent upon particle-size distribution. The phenomenon of bronzing occurred with some pigments mainly in printing inks.Examination of a series of chemically identical red pigments Calcium 4R toners showed that those with marked bronzing contained a high proportion of fine pigment particles (0.08 or 0.12 pm and below). It was shown by electron-micrograph shadowed replica techniques that these fine pigment particles were present on the surface of the ink films in the form of “rafts,” one particle thick. The existence of such discrete layers on the surface of the films could account for the selective reflectance of light which gave rise to the bronzing effect. The hue colour strength and opacity of coloured pigments are related to particle size. A series of ultramarine pigments had been examined. These differed appreciably in tinting strength and there was a difference in hue of the full strength colours.There was a simple relationship between the tinting strength of the pigments and mean particle diameter and surface area the finest pigments with the highest surface areas being the strongest. This gradation of properties arose from the fact that the absorption curves fell in a regular series. 176 PAPERS ACCEPTED FOR THE ANA4LYST IPYOC. S O C . Analyt. Chetvz. As the particle size increased the peaks became broader so that the tints became less saturated. In the full strength colours the coefficients of scatter were of importance and these also fell in a series with particle size. Similar relationships with particle size were found with a series of benzidine-yellow pigments. These differed in hue in full strength the largest sized pigments being greenish yellow in hue.However in tints with white these pigments were the reddest yellow in hue. These differences in behaviour again arose from the fact that in tints with white in which the white pigment supplies all the scatter only the absorption curves are important whereas in full strength the scattering curve is predom- inant. In the green and greenish-yellow regions of the spectrum from 510 to 575 nm the largest sized pigments showed the greatest scatter and the curves fell in a series according to particle size of the pigments. Consequently the largest sized pigments were the greenest. This was also the region of greatest visual perception and consequently the opacity of the pigments fell in the same order. In tints with white however the absorption curves of the largest sized pigments showed broader and shallower peaks than the smaller sized.These larger sized pigments therefore absorbed proportionately more in the blue - violet region and therefore the tints appeared redder in hue. The final example of the effects of the particle size of pigments was concerned with the stabilisation of dispersions against flocculation. Attractive forces existed between the parti- cles in a dispersion and for a given distance of separation these were considerably greater for larger sized particles than for smaller ones. In the solvent-based paint systems examined the electrical charges on the pigments were insufficient to enable an electrical repulsion and stabilisation to occur. Stabilisation occurred by an adsorbed-layer mechanism in whicli the close approach of particles was prevented by the adsorbed polymer. For a given thickness of adsorbed layer larger particles would flocculate to a greater extent than small ones. In agreement with this theory it was found that the degree of flocculation of a series of phthalo- cyanine pigments in alkyd paints measured by counting and sizing coloured flocculates in microtome sections of the paint film showed a high degree of correlation with the weight percentages of the pigments over 0.2 pm in diameter. Similar results were also found in alkyd - amino stoving enamels. These pigments also had the greatest opacity. Changes in the Register of Members DEATHS We record with regret the deaths of Frederick Robinson Russell Gibson Thin.

ISSN:0037-9697    

DOI:10.1039/SA9690600169

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

176 PAPERS ACCEPTED FOR THE ANA4LYST IPrOC. S O C . Analyt. Chetvz. 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. “Preparaticn of Alkali Metal Free Standard Titanium (IV) Solutions,” by V. Zatka. “A Simple Micro Method for the Determination of Copper in Blood Serum,” by I<. Khalifa H. Doss and R. Awadallah. “Determination of Diosgenin in Dioscorea deltoidea and Discorea sylvatica by Using Gas - Liquid Chromatography,” by B. I<. Cooke. “Ion Exchange in Non-aqueous Media The Anion-eschange Behaviour of Phenols on De-Acidite FF Resin in Methanolic Media,” by D. E. Thomas and ,J. D. R. Thomas. “Detection of Chloramine-T in Dairy Products,” by W. F. Van Gils. “A Solvent Extraction Technique with the Technicon Autohalyzer,” by J.M. Carter “An Analytical and Kinetic Investigation of the Vanadium(V) Catalysed Bromate Oxida- Kinetics of the Uncatalysed Rromate Oxidation of and G. Nicltless. tion of Bordeaux. Part I. Bordeaux,” by C. W. Fuller and J. M. Ottaway. September 19691 PUBLICATIONS RECEIVED 177 “-4n Analytical and Kinetic Investigation of the Vanadium(V) Catalysed Bromate Oxidation of Bordeaux. Part 11. Kinetics of the Vanadium(V) Catalysed Bromate Oxidation of Bordeaux,” by C. W. Fuller and J. M. Ottaway. “An Analytical and Kinetic Investigation of the Vanadium(V) Catalysed Bromate Oxidation of Bordeaux. The Catalytic Determination of Vanadium (V),” by C. W. Fuller and J . M. Ottaway. “Separation of Niobium and Tantalum Oxalate Complexes by Yaper Electrophoresis,” “The Automatic Determination of Fluoride in Urine,” by J. A. Hargreaves G. S. Ingram and D. L. Cox. “Spectrophotometric Determination of Yropoxur Residues on Vegetable Matter,” by W. F. Van Gils. “The Determination of Ethanol in Essences Tinctures and Toilet Preparations by Gas Chromatography,” by J. I<. Harris. “Determination of the Hydroxyl-group Content of Epoxy Resins,” by Mrs. E. J. Norton L. Turner and D. G. Salmon. “The Spectrophotomctric Determination of Microgram Amounts of Antimony with Rhodamine S with Application to its Determination in Titanium Dioxide,” by W. Z. Jablonski and C. A. Watson. Part 111. by Betsy Biraben Scott. “Extraction of Hydroxyatrazine from Soil,” by R. J. Hance.

ISSN:0037-9697    

DOI:10.1039/SA9690600176

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

September 19691 PUBLICATIONS KECEIVEI) 177 Notices THE CHEMICAL SOCIETY’S LIBRARY MEMBERS of the Society have the privilege of using the Library of the Chemical Society at Rurlington House London WIV ORN. The following publications of analytical interest have recently been added to the Library. The last list appeared in Proceedings 1969 6 103. Books marked with an asterisk have been reviewed in The AnaZyst. THERMOMETRIC TITRIMETRY. L. S. BARK and S. M. BARK Pergamon Press. 1969. * AN INTRODUCTION TO CHEMICAL NOMENCLATURE. R. S. CAHN. Third Edition. Butterworth. 19GS. 178 NOTICES [Proc. SOC Aizalyt. Chew,. * ISOLATION AND ~LIENTIFICATION OF L)Ru(;s IN PHARMACEUTICALS BODY FLUIDS AND POSTMORTEM AN INTRODUCTION TO PRACTICAL INFRARED SPECTROSCOPY. Third Edition. MATERIAL. Edited b57 E.G. C. CLARKE. The Pharmaceutical Press. London. 1969. Butterworths. 1969. A. D. CROSS and R. A. JONES. MISES AU P O I N T D E CHIME ANALYTIQUE ORGANIQUE 1’HARMACEUTIQUE ET BROMATOLOGIQUE. J. A. GAUTIER. 18th Series. Masson. 1969. Translations. 1968. ANALYTICAL CHEMISTRY OF NIOBIUM AND TANTALUM. T. M. GIBALO. lsrael Program for Scientific * ABSORPTION SPECTRA IN THE ~JLTRAVIOLET AND VISIBLE REGION. Volumes 10 and Edited by L. LANG. 11 and Cumulative Index Volumes 6 to 10. Nauka. 1968. Pergamon Press. 1969. Interscience Publishers. 1967. Office. 1969. McGraw-Hill. 19G8. by A. WEISSBERGEK. Second Edition. lnterscience Publishers. 1968. Ltd. 1969. Akademiai Kiado. 1968. ANALYTICAL CHEMISTRY O F PROTACTINIUM. ANALYTICAL CHEMISTRY O F THE ELEMENTS. E. s. I’RL’SHIN * A4?TALYTICAL APPLICATIONS OF 1,IO-PHENANTHROLINE AND RELATED COMPOUNDS.A. A. SCHILT. ENCYCLOPEDIA OF INDUSTRIAL CHEMICAL ANALYSIS. F. D. SNELL and C. L. HILTON. Volumes 4 5 and 6. * DEVELOPMENT OF THE CHEMICAL BALANCE. A Scicncc Museum Survey. J . T. STOCK. 1H.M. Stationery ELECTRONIC SPECTRA O F ‘rRANSITION MET.4L COMPLEXES AN ~NTRODUCTORY TEXT. n. SUTTON. TECHNIQUE OF ORGANIC CHEMISTRY. VOLUME 9. CHEMICAL APPLICATIONS OF SPECTROSCOPY. Editcd COMPLEXOMETRY WITH EDTA AND RELATED REAGENTS. Third Edition. T. S. WEST. B.1I.H. Chemicals A.C.S. CHEMICAL ABSTRACTS SERVICE THE Chemical Society on behalf of the Consortium on Chemical Information (COCI) has entered into an agreement with the American Chemical Society whereby the Chemical Society will become the sole agents for the sale and distribution in the United Kingdom of the publica- tions and services of the Chemical Abstracts Service.As part of this agreement the American Chemical Society will make available to members of Societies in COCI at the same price as is charged to A.C.S. members Chemical Titles (at the 1970 members’ price of ,f14 10s.) and the following Chemical Abstracts Section Groupings (at L16 10s. each) Biochemistry ; Organic Chemistry ; Macromolecular Chemistry ; Applied Chemistry and Chemical Engineering ; and Physical and Analytical Chemistry. Sales will be handled directly by The Chemical Society Publications Sales Office Blackhorse Road Letchworth Herts. This offer is on the basis that members will order o i d y for their personal use. BRITISH STANDARDS IKSTITUTION DRAFT SPECIFICATIONS A FEW oopies of the following draft specifications issued for comment only arc available to members of the Society and can be obtained from the Secretary The Society for Analytical Chemistry 9/10 Savile Row London W1X 1AF. Draft Specification prepared by Technical Committee CIC/8-Sulphuric Acid for Accumu- 69/18185--Draft B.S. Specification for Sulphuric Acid for Use in Lead-acid Batteries (Limits for Impurities) (Revision of BS 3031 :1958). 69/18795-Draft B.S. Methods of Test for Whiting. lators. Draft Specification prepared by Technical Committee CIC/lS-Whiting.

ISSN:0037-9697    

DOI:10.1039/SA969060177b

出版商:RSC    

年代:1969

数据来源: RSC