February, 1979 SUMMARIES OF PAPERS I N THIS ISSUE iiiSummaries of Papers in thisSub -micrometre Particle Size Characterisation and Distribution byMercury PenetrationThe technique of mercury porosimetry is usually regarded as a method for thedetermination of surface areas and the evaluation of pore size distributions inporous solids. With fine non-porous or microporous materials the initial low-pressure region of a mercury penetration graph can be used to determine theinter-particle spaces or voids in an assembly of discrete particles.A determination of the particle size and distribution of three powders, in theone micrometre and sub-micrometre size range, has been obtained frommercury porosimetry breakthrough and intrusion pressures. The mercuryintrusion particle diameters and distributions are compared with valuesobtained by gravitational and centrifugal sedimentation methods and electronmicroscopy counts for particle size measurement.Keywords : Pavticle size chavactevisation ; mevcuvy fienetvationNAYLAND G.STANLEY-WOODPostgraduate School of Studies in Powder Technology, University of Bradford, GreatHorton Road, Bradford, BD7 1DP.Analyst, 1979, 104, 97-105.Determination of Acrylonitrile Monomer in Plastic Packaging andBeverages by Headspace Gas ChromatographyA gas - liquid chromatographic method for determining trace amounts ofacrylonitrile in plastic containers and carbonated beverages using a nitrogen-sensitive detector and headspace injection technique is described. The methodis suitable for the determination of acrylonitrile a t concentrations down to0.1 mg kg-l in plastics and 0.005 mg kg-l in beverages.Keywovds : A cvylonitvile deterwination ; headspace gas chvomatogvafihy ;plastic packaging; foodstuflsG. B.-M.GAWELLNational Food Administration, Food Research Department, Box 622, S-751 26Uppsala, Sweden.Analyst, 1979, 104, 106-110.Determination of Ethylenethiourea in EthylenebisdithiocarbamateFungicides : Comparison of High-performance LiquidChromatography and Gas - Liquid ChromatographyA rapid, sensitive method is described for the determination of ethylene-thiourea (imidazolidine-2-thione) in ethylenebisdithiocarbamate fungicides.High-performance liquid chromatography is used with an ultraviolet spectro-photometric detector.The results are compared with those obtained usinggas - liquid Chromatography. All fungicide samples assayed containedethylenethiourea, and gas - liquid chromatography indicated higher con-centrations than high-performance liquid chromatography.Keywords 1 Ethylenethiouvea determinatiow ; ethylenebisdithiocavbamate fungi-cides ; high-pevfovmance liquid chvomatogvaphy ; gas - tiquid chvomato-P P h YD. S. FARRINGTON and R. G. HOPKINSDepartment of Industry, Laboratory of the Government Chemist, Cornwall House,Stamford Street, London, SE1 9NQ.Analyst, 1979, 104, 111-116iv SUMMARIES OF PAPERS I N THIS ISSUEFluorimetric Determination of Acetohexamide in Plasma andTablet Formulations Using 1 - MethylnicotinamideFebruary, 1979A sensitive method is described.for the fluorimetric determination of aceto-hexamide in plasma or in tablets by means of its reaction with l-methyl-nicotinamide, which is shown to be a useful reagent for the determination ofketonic compounds. The limit of detection is approximately 0.2 p g ml-land the relative standard deviation is 3.1% for 2 pg ml-l in plasma.Acetoacetic acid usually does not interfere, but can be separated, if necessary,from acetohexamide by means of a .washing technique. No interference iscaused by the presence of insulin, other (non-ketonic) oral hypoglycaemicdrugs, acetone or pyruvic or cc-ketoglutaric acid.Keywords A cetohexamide determination ; plasma ; tablets ; l-methylnicotin-amide reagent ; spectro$uorimetryPAMELA GIRGIS-TAKLA and IOANNIS CHRONEOSWelsh School of Pharmacy, University of Wales Institute of Science and Tech-nology, King Edward VII Avenue, Cardiff, CF1 3NU.Analyst, 1979, 104, 117-123.Polarographic Determination of Trace Elements in Foodfrom a Single DigestThe determination of 12 trace elements, namely copper, zinc, mercury, lead,cadmium, iron, tin, chromium, arsenic, antimony, selenium and tellurium, inadmixture by means of a cathode-ray polarograph is described. The elementswere investigated in concentrations ranging from 0.1 to 20 p.p.m. by meansof normal, reverse-sweep or resistance - capacitance derivative techniques.The last technique could not be used for mercury, although it was used forall the other elements in concentrations less than 1 p.p.m.The completedetermination took 4-7 h, and was applied to various kinds of food, such asbread, meat and vegetables.Keywords : Trace element determination ; food analysis ; polarography ; singledigestM. KAPEL and M. E. KOMAITISProcter Department of Food Science, The University of Leeds, Leeds, LS2 9JT.Analyst, 1979, 104, 124-135.Apparatus for the Automatic Preparation of Soil Extracts forMineral-nitrogen DeterminationAn apparatus is described that automatically prepares samples and feeds anAutoAnalyzer system. It consists of a reagent adder, which adds the correctvolume of extractant for an approximately weighed amount of soil, and asample preparation unit, which mixes, filters, dilutes and loads samples on toan AutoAnalyzer sampler. The results obtained using the apparatus were ingood agreement with those obtained by manual sample preparation.Keywords Mineral-nitrogen deternzination ; soil analysis ; automatic extvactionJ. A. P. MARSH, R. KIBBLE-WHITE and C. J. STENTAgricultural Research Council Weed Research Organization, Begbroke Hill, Yarnton,Oxford, OX6 1PF.Analyst, 1979, 104, 136-142