1、Designation:D788420Standard Test Method forDetermination of 4-Carboxybenzaldehyde and p-Toluic Acidin Purified Terephthalic Acid by Reverse Phase HighPerformance Liquid Chromatography1This standard is issued under the fixed designation D7884;the number immediately following the designation indicates
2、 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 the4-Car
3、boxybenzaldehyde(4-CBA)and p-Toluic acid(p-TOL)in purified terephthalic acid(PTA)by reverse phase highperformance liquid chromatography(HPLC).This method isapplicable for 4-CBAfrom 2 to 500 mg/kg and for p-TOLfrom10 to 500 mg/kg,respectively.1.2 In determining the conformance of the test results usi
4、ngthis 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
5、 of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in acco
6、r-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM St
7、andards:2D1193 Specification for Reagent WaterD6809 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 SpecificationsE682 Practice for Liquid Chromatography Term
8、s and Rela-tionshipsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Document:3EN ISO 8213 Chemical products for industrial useSampling techniquesSolid chemical products in theform of particles varying from powders to coarse lumps2.3 Other Docum
9、ent:4OSHA Regulations,29 CFR paragraphs 1910.1000 and1910.12003.Summary of Test Method3.1 Reverse Phase HPLC MethodPTAsample is dissolvedin ammonium hydroxide solution,and a fixed volume of thissolution is injected into a high performance liquid chromato-graph equipped with a UV detector.A C18 chemi
10、cally bondedcolumn is used to separate the impurities 4-CBA and p-TOLfrom PTA.The external standard calibration is used forquantification.4.Significance and Use4.1 The presence of 4-CBA and p-TOL in PTA used for theproduction of polyester is undesirable because they can slowdown the polymerization p
11、rocess and 4-CBA imparts color-ation to the polymer due to thermal instability.4.2 Determining the amount of 4-CBA and p-TOL remain-ing from the manufacture of PTA is often required.This testmethod is suitable for setting specifications and for use as aninternal quality control tool where these prod
12、ucts are producedor are used.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic,Industrial,Specialty and Related Chemicals and is the direct responsi-bility of Subcommittee D16.02 on Oxygenated Aromatics.Current edition approved Oct.1,2020.Published December 2020.Originally
13、approved in 2013.Last previous edition approved in 2019 as D7884 19.DOI:10.1520/D7884-20.2For 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 p
14、age onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.4Available 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.*
15、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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization establishe
16、d in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.15.Apparatus5.1 High Performance Liquid Chromatograph(HPLC)Any HPLC capable of pumping the mobile phase at flow ratesbetween 0.1 and 2.0 mL/min,with a pressure between 0 and 40MPa and a pulsation of less than 1%full scale deflection underthe test conditions described in Table 1.The S/N(signal tonoise)ratio should
