ASTM_D_7011_-_15.pdf

Designation:D701115Standard Test Method forDetermination of Trace Thiophene in Refined Benzene byGas Chromatography and Sulfur Selective Detection1This standard is issued under the fixed designation D7011;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 thiophenein refined benzene using gas chromatography and sulfurselective detection.The test method is applicable to thedetermination of thiophene at levels of 0.02 to 2.18 mgthiophene per kg in benzene(mg/kg)on the AED,0.03 to 1.87mg/kg on the PFPD,and 0.03 to 2.11 mg/kg on the SCD.Therange of the test method may be extended by modifying thesample injection volume,split ratios,calibration range,orsample dilution with thiophene-free solvent.1.2 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 E29.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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.For specific hazardstatements,see Section 7.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD2359 Specification for Refined Benzene-535D3437 Practice for Sampling and Handling Liquid CyclicProductsD4734 Specification for Refined Benzene-545D4735 Test Method for Determination of Trace Thiophenein Refined Benzene by Gas ChromatographyD5871 Specification for Benzene for Cyclohexane Feed-stockD6809 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 SpecificationsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 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 The thiophene concentration in refined benzene is de-termined at the sub-mg/kg to low mg/kg level using conven-tional gas chromatography with a sulfur selective detector.Areproducible volume of sample is injected.Quantitative resultsare obtained by the use of the external standard calibrationtechnique.3.2 The method allows the use of a sulfur chemilumines-cence detector,atomic emission detector,pulsed flame photo-metric detector,or any other sulfur selective detector providedthat its performance meets requirements as set forth in 5.4.Assulfur compounds elute from the gas chromatographic column,they are detected and quantified.While the benzene moleculedoes not contain any sulfur atoms,the possibility of matrixquenching and interference is a concern,especially for thio-phene determination at levels less than about 0.5 mg/kg.Thecolumn and conditions specified in Table 1 yield acceptableresults with minimal matrix quenching and interference.Em-ploying the column and conditions listed in Table 1 is not a1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved June 1,2015.Published July 2015.Originally approvedin 2004.Last previous edition approved in 2010 as D7011 10a.DOI:10.1520/D7011-15.2For 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 requirement to meet the needs of all users.For example,thereis less concern of quenching and interference encountered withthiophene concentration levels greater than 0.5 mg/kg.Users offlame photometric detectors should refer to Test MethodD4735.4.Significance and Use4.1 Accurate gas chromatographic determination of tracelevels of thiophene in benzene involves special analyticalproblems because of the difficulties of trace level analysis.These problems arise from the low conce