X SUMMARIES OF PAPERS I N THIS ISSUEStudies in Gas Chromatography - Chemical IonisationMass Spectrometry of Some Silicate AnionsAugust, 1979Chemical ionisation mass spectrometry of trimethylsilyl derivatives of theanions SO,*-, Si,O,6-,Si,O06- and Si, OIo8- has been studied using isobutaneas the reagent gas. The protonated molecular ion was observed in all recordedspectra. Also, the chemical ionisation spectra showed much fewer fragmentpeaks when compared with the corresponding electron impact spectra.Keywords : Chemical ionisation mass spectrometry ; silicate anionsJ. B. ADDISONAtlantic Regional Laboratory, National Research Council of Canada, Halifax, NovaScotia, Canada, B3H 321.Analyst, 1979, 104, 766-770.Internal Standardisation and its Value in the Assessment of theSuitability of the Column for Quantitative High-performanceLiquid ChromatographyThe requirement that the best precision be obtained for a pharmaceuticalraw material assay using automated high-performance liquid chromatography,with valve injection, over long runs, suggested that the inclusion of an internalstandard would be beneficial in allowing an additional method for the calcula-tion of results.The accurate volume injection of the valve and loop systemthus permitted standard calibration and subsequent sample evaluation bythe peak-height ratio method as well as from absolute peak heights alone.After a number of experiments, column deterioration rendered the assaysinvalid, and retrospective analysis of the data demonstrated the merits ofinternal standard related parameters in showing the decline in performanceof the column.The major benefits derived from the approach adopted were criteria forjudging the acceptability of the assay results, without excessive replicationfor a particular sample, and prior-warning of the need to re-pack the column.Keywords : Quantitative high-performance liquid chromatography ; internalstandardisation ; column assessment ; Pharmaceutical analysis ; automaticinjectionR.A. MOORELilly Research Centre Ltd., Erl Wood Manor, Windlesham, Surrey, GU20 6PH.Analyst, 1979, 104, 771-777SUMMARIES OF PAPERS IN THIS ISSUEDetermination of Small Amounts of Selenium in Organic MatterAugust, 1979Report prepared by the Metallic Impurities in Organic Matter Sub-committeeMethods for determining small amounts of selenium in organic matter havebeen examined.Determination first requires oxidative destruction of organicmatter. The usual oxidising systems employing sulphuric acid initially,with hydrogen peroxide, nitric and/or perchloric acids, gave very low recoveriesof selenium when high proportions of fats were present in the samples. Con-tinuous combustion and oxygen flask methods were also unsatisfactory. Awet-oxidation procedure in which nitric and perchloric acids (5 + 1) werefollowed by nitric and sulphuric acids gave satisfactory ,results. It wasimportant to ensure that selenium was present as selenium(1V) by boiling thesolution with hydrochloric acid after the oxidation.Colorimetric, gas - liquidchromatographic, fluorimetric and atomic spectroscopic methods were con-sidered for the selenium determination; of these, the last two were selectedfor collaborative trials. For the fluorimetric finish, the solution, after oxida-tion, was treated with 2,3-diaminonaphthalene reagent, the complex wasextracted with cyclohexane or dekalin and the fluorescence in the organicphase was measured in a spectrofluorimeter with excitation a t 369nm andemission reading a t 525 nm. Atomic-absorption or fluorescence measure-ments were made after hydrogen selenide generation and atomisation. Theprecisions of analyses for samples with selenium contents from less than0.1 to 10 pg g-l by the fluorimetric and hydride generation methods areillustrated.Keywords : Selenium determination ; wet oxidation ; fluorimetry ; atomicspectroscopyANALYTICAL METHODS COMMITTEEThe Chemical Society, Burlington House, London, W1V OBN.Analyst, 1979, 104, 778-787.Hydrocarbon Analysis of Naphtha Using Capillary-columnGas Chromatography Under Isothermal ConditionsShort PaperKeywords : Hydvocarbon analysis ; naphtha ; capillary-column gas chromato-graphy ; Kovdts retention indicesPRADEEP KUMAR, S. L. S. SAROWHA and P. L. GUPTAIndian Institute of Petroleum, Dehra Dun-248005, India.Analyst, 1979, 104, 788-792.The Impact Cup: A Simple Aid in Flame SpectrometricAnalysis at High Analyte ConcentrationsShort PaperKeywords : Impact cup ; flame spectrometry ; high analyte concentrations ;pneumatic nebuliserMALCOLM S . CRESSERDepartment of Soil Science, University of Aberdeen, Meston Walk, Aberdeen,AB9 2UE.Analyst, 1979, 104, 792-796