ASTM_D_8032_-_20.pdf

Designation:D803220Standard Test Method forAcid Number of Terephthalic Acid by Color-IndicatorTitration1This standard is issued under the fixed designation D8032;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 acidnumber of terephthalic acid(TA)by color-indicator titration.Acid number of TA product is usually within 674 to 676 mgKOH/g.1.2 In determining the conformance of the test results usingthis method,results shall be rounded off in accordance with therounding-off method of Practice 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-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 Standards:2D974 Test Method for Acid and Base Number by Color-Indicator TitrationD1193 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 MethodsE300 Practice for Sampling Industrial ChemicalsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 Other Document:3OSHA Regulations,29 CFR paragraphs 1910.1000 and1910.12003.Terminology3.1 Definitions:3.1.1 acid number,nthe quantity of base,expressed inmilligrams of potassium hydroxide per gram of sample that isrequired to titrate a sample in a specified solvent to a specifiedend point.4.Summary of Test Method4.1 A TA sample is dissolved in dimethyl sulfoxide andtitrated with standard sodium hydroxide solution to the endpoint indicated by the color change of the added phenolphtaleinsolution(colorless in acid and pink in base).The acid numberis calculated as milligrams of KOH per gram of TA sample.Itstheoretical value of TA sample is 675.5 mg KOH/g.5.Significance and Use5.1 An estimate of TA purity can be determined by titratingwith KOH.As an index of TA purity,the acid number can beused as a guide in the quality control of TA production.6.Apparatus6.1 Analytical Balance,capable of weighing 60.0001 g.6.2 Burets,50-mL with 0.1-mL graduations.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 Aug.1,2020.Published September 2020.Originallyapproved in 2016.Last previous edition approved in 2016 as D8032 16.DOI:10.1520/D8032-20.2For 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 page onthe ASTM website.3Available from U.S.Government Printing Office,Superintendent ofDocuments,732 N.Capitol St.,NW,Washington,DC 20401-0001,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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established 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.7.Reagents7.1 Purity of ReagentsUnless otherwise indicated,it isintended that all reagents shall conform to the reagent gradespecification of the Analytical Reagents of the AmericanChemical Society,4where such specifications are available.Other grades may be used,provided it is first ascertained thatthe reagent is of sufficient high purity to permit its use withoutlessening the performance or accuracy of the determination.Reagent chemicals shall be used for all tests.7.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean Type III of SpecificationD1193.Boil the water gently for 5 to 10 min to