... May, 19661 THE ANALYST 111'ORGANIC REAGENTSFOR METALSAND OTHER REAGENTM ONOG RAPHS'VOLUME 2,1964. Published by Hopkin & Williams Limited, price 30/-d.A companion to Volume 1, 1955, price 15,'-d, the second volumecontains all monographs in the series "Organic Chemical Reagents"issued since Volume 1 together with many new ones and representsworkverified or originated in our own Laboratories. It deals with 28colorimetric and gravimetric reagents and includes a section oncompleximetry, with 1 5 metallochromic indicators.'BIOCHEMICALS'A CATEGORISED PRICE-LIST OF SUBSTANCES USED IN BIOCHEMISTRYFor many years the H €t W Chemical Catalogue has included sub-stances of biochemical interest. These, together with a preliminaryrange of over 60 additional biochemicals, selected on the advice ofour biochemical consultants, are now published as a separate price-list with technical information and specifications where appropriate.T Hopkin & Williams Limited, Freshwater Road, Chadwell Heath,Essex, England.Please send me ..................... copy(s) of "OrganicReagents for Metals and Other Reagent Monographs" Volume 2,1964 price 30/-d and ..................... free copy(s) of "Biochemicals"0NAME ..........................................................................................................................................................................POSlTl ON ..............................................................................................................................................................COMPANY ...........................................................................................................................................................ADDRESS ..............................................................................................................................................................All substances mentioned inthese publications are available from :HOPKIN & WILLIAMS LIMITED, Chadwell Heath, Essex, England.Telephone : GOOdmayes 2436CHEMICALS FOR RESEARCH, ANALYSIS AND INDUSTRYTRADE MARK TAR/HW.3iv SUMMARIES OF PAPERS I N THIS ISSUE [May, 1966Summaries of Papers in this IssueThe Quantitative Microanalysis of Carbonyl Compoundsseveral published methods for preparing 2,4-dinitrophenylhydrazonesand determining them colorimetrically have been examined, and a practicalsystem of analysis has been devised from them.The key step is the use ofa 2,4-dinitrophenylhydrazine - 66 per cent. phosphoric acid column elutedwith benzene, as well as light petroleum.The results of an analysis in the difficult case of a butter fat are described.A. M. PARSONSUnilever Research Laboratory, Welwyn, Herts.Analyst, 1966, 91, 297-305.Calibration of a Fisher Air-permeability Apparatus forDetermining Specific SurfaceCalibrating the Fisher sub-sieve sizer at a single particle-size level doesnot ensure accuracy a t other levels unless several variables are controlled.Instrument modifications that give better control of the several variables,and a calibration method that ensures accurate air-flow measurement withoutdepending on a particle-size standard, are described.The modified instrumenthas good precision over the range 2 to 40,~. A method for extending thisrange is given.I. C. EDMUNDSONGlaxo Laboratories Ltd., Greenford, Middlesex.Analyst, 1966, 91, 306-315.A Study of the Macroscopic Distribution of Oxygen in a Steel Rodby Neutron- activation and Vacuum Fusion TechniquesThe distribution of oxygen was determined along the length of a steelrod. Neutron-activation and vacuum fusion techniques were used alterna-tively, and the relevant pieces of apparatus and methods are described. Theover-all average oxygen content determined by neutron-activation analysiswas 129 p.p.m., in excellent agreement with 128 p.p.m.found by vacuumfusion. The results further show the continuity between the two sets of results,and also a definite inhomogeneity in the macroscopic distribution of oxygen.JUSTUS M. van WYK,* MARC Y. CUYPERS,? LLOYD E. FITEt andRICHARD E. WAINERDIt* Basic Research Division, Research and Process Development, South African Iron?Activation Analysis Research Laboratory, Texas A and M University, CollegeAnalyst, 1966, 91, 316-323.and Steel Industrial Corporation, Pretoria, South Africa.Station, Texas, U.S.A.Quasi-quantitative Separation of Paraffins and OlefinsBy the addition of iodine monochloride to a mixture of paraffins and olefins,an easy chromatographic operation on silica gel of the two is made possibleby virtue of the olefin adduct being much more strongly adsorbed.Theolefins are regenerated by refluxing the halogenated derivative with ethanoland excess sodium iodide.The efficacy of the method has been proved on the total aliphatics oflow temperature tars and on pairs of pure n-paraffins and 1-olefins of thesame carbon number. The small losses incurred are almost entirely inthe olefins.J. A. SPENCE and M. VAHRMANNorthampton College of Advanced Technology, St. John Street, London, E.C. 1.Analyst, 1966, 91, 324-327vi SUMMARIES OF PAPERS I N THIS ISSUEA Study of the Determination of Thiamine in Breakfast CerealsThe method of determining thiamine that involves the purification bybase-exchange on sand is satisfactory for materials of the “breakfast cereal”type.Traces of materials responsible for errors in the direct determinationremain after treatment, but the errors are greatly reduced and oppose oneanother, so that they may reasonably be neglected.H. N. RIDYARDThe Research Association of British Flour-Millcrs, Ccrcals Research Station, OldLondon Road, St. Albans, Herts.Analyst, 1966, 91, 328-332.[May, 1966The Assay of NeomycinShort PaperR. A. HOODLESSMinistry of Technology, Laboratory of the Government Chemist, Cornwall House,Stamford Street, London, S.E. 1.Analyst, 1966, 91, 333-334.Removal of Polyphenolic Compounds Interfering with CarbohydrateDeterminations in Plant Extracts with an InsolublePolyphenol AdsorbentShort PaperG.W. SANDERSON and B. P. M. PERERATea Research Institute of Ceylon, Talawakelle, Ceylon.Analyst, 1966, 91, 335-336.The Detection of Dinitro and Trinitro Aromatic Bodies inIndustrial Blasting ExplosivesShort PaperS. A. H. AMAS and H. J. YALLOPRoyal Armament Research and Development Establishment, Fort Halstead, Kent.Analyst, 1966, 91, 336-337.The Use of Molecular Sieve 5A for Collecting Fractionsfrom a Gas ChromatographShort PaperM. CARTWRIGHT and A. HEYWOODImperial Chemical Industries Ltd., Dyestuffs Division, Hexagon House, Blackley,Manchester 9.Analyst, 1966, 91, 337-338AEl SCIENTIFIC APPARATUSBULLETIN NO. 4Ag 1 150 210 1 1.4 23Ga ~ 80 250 3.1 1 271IMPROVED ACCURACY IN THEANALYSIS OF SOLIDS BY SPARKMASS SPECTROMETRY2113Since the possibility of using spark source ionization for the analysis of solidswas first recognised ten years ago, the design of the double focusing massspectrometer using Mattauch geometry has been considerably improved.Andtoday one instrument-namely the AEI MS7-is capable of detecting im-purities at levels as low as 1 part in lo9. As a result the MS7-which, incident-ally, was the first commercially available double focusing instrument to bebuilt expressly for the analysis of solids-has found wide applicationsparticularly where overall coverage of all elements and comparison analysiswithout standards are valuable.Now the MS7 technique has been further improved by the careful control ofcertain parameters, and very good reproducability and accuracy can beguaranteed.This bulletin reviews the parameters affecting analytical accuracyand outlines the methods of control developed by AEI engineers.It has been shown that the sensitivityof the majority of elements differs fromsome standard such as iron by no morethan a factor of 3. In other words, mostrelative sensitivity factors lie between0.3 and 3. In the case of the MS7, thedetermination of relative sensitivityfactors is considerably simplified bythe fact that the response of the instru-ment is linear over a very large rangeof concentration. Indeed Hannay &Ahearn’ established linearity over therange lo4 to 1 using doped siliconsamples. More recently, W. A. Wolsten-holme (AEl Consultant Lab.) hasreported on the investigation of golddoped titanium samples covering a con-centration range from 0.5% to .02 ppmby weight; a range of more than l o 5to 1.These samples were chosen because oftheir suitability for neutron activationand wet chemical analysis.Figure 1shows the relative ion intensity of goldplotted against the concentration de-termined by chemical or neutron acti-FOOTNOTE :I Hannay and Ahearn (1954) Anal. Chem 261956.FIG. 1 /vation techniques. The “just detect-able” line is an individual assessmentfor ion intensity and the “densito-metric” line indicates that a micro-densitometer was used to scan thespectral lines; the two graphs havebeen displaced for the sake of clarity.Matrix effects are generally very small,as is illustrated by the relative sensi-tivities for copper and steel standardsreported in tables 1 and 2.In copper and steel relative sensitivitiesare very similar for chromium (1.8 and1.4) and for tin (1.3 and 1.1). Onlyforsome low BP elements is there amarked dependence on the matrix, e.g.(1.4 and 2.6) for lead.NOTE :Relative Sensitivity = uncorrected MS7known valueHomogeneity ofstandards and samplesCare has to be taken to use homo-geneous standards or alternatively toincrease the rate of consumption ofsample above the usual 5 to 10 milli-grams.As it happens, however, the possibilityof inadvertently using an inhomogene-ous sample has been materially reducedby the introduction of more reliablemethods of sample preparation.Cr ! 60 110 1 1.8 1 20 1 2