ASTM_D_7881_-_13.pdf

Designation:D788113Standard Test Method forDetermination of 4-Carboxybenzaldehyde and p-Toluic Acidin Purified Terephthalic Acid by Capillary Electrophoresiswith Reverse Voltage Mode1This standard is issued under the fixed designation D7881;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.Scope1.1 This test method2covers the determination of4-carboxybenzaldehyde(4-CBA)and p-toluic acid(p-TOL)inpurified terephthalic acid(PTA)by capillary electrophoresis(CE)with reverse voltage mode and UV detection.It isapplicable for 4-CBAfrom 3 to 400 mg/kg and for p-TOLfrom8 to 400 mg/kg,respectively.1.2 In determining the conformance of the test results usingthis method to applicable specification,results shall be roundedoff in accordance with the rounding-off method of PracticeE29.1.3 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.2.Referenced Documents2.1 ASTM Standards:3D1193 Specification for Reagent WaterD4790 Terminology of Aromatic Hydrocarbons and RelatedChemicalsD6809 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 Method2.2 ISO Documents:4EN ISO 8213 Chemical Products for Industrial UseSampling TechniquesSolid Chemical Products in theForm of Particles Varying from Powders to Coarse Lumps2.3 Other Document:5OSHA Regulations,29 CFR paragraphs 1910.1000 and1910.12003.Terminology3.1 Definitions of Terms Specific to Reverse Voltage Mode inthis Standard:3.1.1 capillary electrophoresis,nan electrophoretic tech-nique in which a sample is introduced into a 50 m to 100 mi.d.fused-silica capillary filled with electrolyte solution andsubjected to high voltage for separation.3.1.1.1 DiscussionReverse voltage,with the cathode onthe injection side and the anode on the detection side,is appliedacross the capillary causing electrolyte and analytes to migratetowards the anode and through the capillarys UV detectorwindow.Analytes are separated based upon the differentialrates of migration in the electrical field.Analyte detection andquantitation are based upon the principles of UV detection.3.1.2 electrolyte,na combination of a buffer reagent,anion-pair reagent and an electroosmotic-flow modifier placedinside the capillary,used as a carrier for the analytes,and fordetection and quantitation.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.02 on Oxygenated Aromatics.Current edition approved Aug.15,2013.Published October 2013.DOI:10.1520/D7881-13.2This standard is based on SH/T 16872000 Purified terephthalic acid forindustrial usedetermination of 4-Carboxybenzaldehyde and p-Toluic Acid-Highperformance capillary electrophoresis(HPCE),copyright SINOPEC,22 Chaoyang-men North Street,Chaoyang District,Beijing,China 100728.A copy of SH/T16872000 may be obtained from China Petrochemical Press,www.sinopec-.3For 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.4Available from Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.5Available 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.3 electroosmotic flow(EOF),nthe directional velocityof electrolyte-solution flow within the capillary under anapplied voltage;the velocity and direction of flow are deter-mined by electrolyte chemistry,capillary-wall chemistry,andapplied voltage.3.1.4 electroosmotic-flow modifier(OFM),na cationicquaternary amine in the electrolyte that dynamically coats thenegatively charged silica wall giving it a net positive charge.3.1.4.1 DiscussionThis modifier reverses the direction ofthe electrolytes natural electroosmotic flow and directs ittowards the anode and detector.This modifier augments theanalytes