ASTM_D_7347_-_07e1.pdf

Designation:D7347071Standard Test Method forDetermination of Olefin Content in Denatured Ethanol bySupercritical Fluid Chromatography1This standard is issued under the fixed designation D7347;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEAdded research report footnote to Section 13 editorially in October 2008.1.Scope1.1 This test method covers the determination of the totalamount of olefins in denatured ethanol to be used as anoxygenate additive in blended spark ignition engine fuels.Themethod of determination is supercritical fluid chromatography(SFC).The application range is from 0.1 to 1.0 mass percenttotal olefins.Results are expressed in terms of mass percentolefins.1.2 This test method can be used for the analysis ofdenatured ethanol that is intended to be used as an oxygenateadditive in commercial spark ignition engine fuels.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D4052 Test Method for Density,Relative Density,and APIGravity of Liquids by Digital Density MeterD5186 Test Method for Determination of the AromaticContent and Polynuclear Aromatic Content of DieselFuels and Aviation Turbine Fuels By Supercritical FluidChromatographyD6550 Test Method for Determination of Olefin Content ofGasolines by Supercritical-Fluid Chromatography3.Terminology3.1 Definitions:3.1.1 critical pressure,nthat pressure needed to condensea gas at the critical temperature.3.1.2 critical temperature,nhighest temperature at whicha gaseous fluid can be converted to a liquid by means ofcompression.3.1.3 supercritical fluid,nfluid maintained in a thermody-namic state above its critical temperature and critical pressure.3.1.4 supercritical fluid chromatography,n class of chro-matography that employs supercritical fluids as mobile phases.4.Summary of Test Method4.1 A small aliquot of the denatured alcohol sample isinjected onto a set of three analytical chromatographic columnsconnected in series.The sample is transported through thecolumns using supercritical carbon dioxide(CO2)as themobile phase.The first column is packed with polyvinylalcohol(PVA).The second column in the series is an analyticalcolumn packed with high surface area silica gel particles,andthe third column is packed with silica particles coated withstrong cation exchange material loaded with silver ions.4.2 Two six-port switching valves are used to direct thedifferent classes of components through the chromatographicsystem to the detector.In a forward flow mode,saturates,aromatics,and olefins pass onto the analytical silica gel columnwhile the alcohol is retained on the PVAcolumn.The saturates,aromatics,and olefins are maintained on the silica column,while the alcohol is back-flushed to the detector.This step freesthe flow path of alcohol species allowing for the separation ofthe olefins from saturates and aromatics.The forward flowmode is resumed after the alcohol is eliminated and saturatesare carried to the detector,while the aromatics are retained onthe silica column and the olefinic species are trapped on thesilver-loaded column.The next step is to back-flush the olefinsfrom the silver-loaded column to the detector.Finally thearomatics are carried from the silica column to the detector ina forward flow mode,bypassing the silver-loaded column.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.04.0C on Liquid Chromatography.Current edition approved Aug.1,2007.Published September 2007.DOI:10.1520/D7347-07E01.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.3 A flame ionization detector(FID)is used for quantita-tion.Calibration is based on the area of the chromatographicsignal for olefins,relative to standard reference materials,which contain a known mass percent of total olefins ascorrected for density.5.Significance and Use5.1 Olefinic hydrocarbons that may be present in denaturedethanol have been demonstrated to contribute to photochemicalreactions in the atmosphere,and this can result in the formationof smog in