ASTM_D_4492_-_10.pdf

Designation:D449210Standard Test Method forAnalysis of Benzene by Gas Chromatography1This standard is issued under the fixed designation D4492;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.1.Scope*1.1 This test method covers the determination of normallyoccurring trace impurities in,and the purity of,finishedbenzene by gas chromatography.1.2 This test method is applicable for benzene purities of99.80 weight%or higher.1.3 The lower limit for detection for non-aromatic impuri-ties is 50 mg/kg.The lower limit of detection for individualaromatic hydrocarbon impurities 10 mg/kg.The lower limit ofdetection for 1,4-dioxane is 5 mg/kg.1.4 In determining the conformance of the test results usingthis method to applicable specifications,results shall berounded off in accordance with the rounding off method ofPractice E29.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 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.For specific hazardstatements,see Section 8.2.Referenced Documents2.1 ASTM Standards:2D852 Test Method for Solidification Point of BenzeneD3437 Practice for Sampling and Handling Liquid CyclicProductsD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and Relation-shipsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs2.2 Other Document:OSHA Regulations,29 CFR paragraphs 1910.1000 and1910.120033.Summary of Test Method3.1 A known amount of an internal standard is added to thespecimen.A small volume of this mixture is injected into a gaschromatograph equipped with a flame ionization detector(FID)and a capillary column.3.2 The peak area of each impurity and the internal standardis measured by an electronic integrator.The concentration ofeach impurity is calculated from the ratio of the peak area ofthe internal standard versus the peak area of the impurity.Purity is calculated by subtracting the sum of the impuritiesfound from 100.00 weight%.Results are reported in weightpercent for purity and total impurities,individual impurities arereported in units of mg/kg.4.Significance and Use4.1 This test method is suitable for determining the concen-trations of known impurities in finished benzene and for use asan integral quality control tool where benzene is either pro-duced or used in a manufacturing procedure.It is generallyapplied to impurities such as nonaromatics containing ninecarbons or less,toluene,C8 aromatics,and 1,4-dioxane.4.2 Absolute purity cannot be determined if unknown im-purities are present.Test Method D852 is generally used as acriteria for determining the absolute purity.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.01 on Benzene,Toluene,Xylenes,Cyclohexane and TheirDerivatives.Current edition approved March 15,2010.Published May 2010.Originallyapproved in 1985.Last previous edition approved in 2007 as D4492 07.DOI:10.1520/D4492-10.2For 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.3Available from U.S.Government Printing Office Superintendent of Documents,732 N.Capitol St.,NW,Mail Stop:SDE,Washington,DC 20401,http:/www.access.gpo.gov.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Interferences5.1 Benzene is typically resolved from naturally occurringcomponents with boiling points 138C.Naturally occurringcomponents include nonaromatic hydrocarbons,toluene,C8aromatics,and 1,4-dioxane.An adequate separation of knownimpurities from benzene should be evaluated for the columnselected.5.2 The internal standard chosen must be sufficiently re-solved from any impurity and the benzene peak.6.Apparatus6.1 Gas ChromatographAny chromatograph having aflame ionization detector that can be operated at the conditionsgiven in Table 1.The system should have suffici