ASTM_D_8063_-_18.pdf

Designation:D806318Standard Test Method forWater in Purified Terephthalic Acid(PTA)by Volumetric KarlFischer Titration1This standard is issued under the fixed designation D8063;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 method covers the determination of water inpurified terephthalic acid(PTA)between 0.01 and 1.00%(w w)by Volumetric Karl Fischer Titration.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,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:2D1193 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 MethodsE203 Test Method for Water Using Volumetric Karl FischerTitrationE300 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.Summary of Test Method3.1 A PTA sample is dissolved in a solvent(mixture ofmethanol and pyridine,in the range of 30 35%methanol and70 65%pyridine)and titrated with Karl Fischer reagent,which consists of iodine,sulfur dioxide,methanol and anorganic base.3.2 In the Karl Fischer reaction,water will react with iodineaccording to the following equation:H2O1I21SO213RN1CH3OH2RNHI1RNHSO4CH33.3 The volume of Karl Fischer reagent consumed to titratethe sample is converted into the amount of water in the testPTA sample.4.Significance and Use4.1 The presence of water in PTAused for the production ofpolyester is undesirable because it reduces the purity of thePTA.4.2 Determining the amount of water content remainingfrom the manufacture of PTA is often required.This testmethod is suitable for setting product specifications and for useas an internal quality control tool where these products areproduced or are used.5.Interference5.1 Certain compounds or classes of compounds interferewith the accurate determination of water by the Karl Fischer1This 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 Jan.1,2018.Published May 2018.DOI:10.1520/D8063-18.2For 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.Copyright 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.1 test method.They include aldehydes,ketones,free halogens,ferric salts and strong oxidizing and reducing agents.6.Apparatus6.1 Karl Fischer Volumetric Titrator,consisting of a titra-tion cell,dual platinum electrode,magnetic stirrer,dispensingburette(2 or 5 mL)and control unit.Any Karl Fischer Titratorcapable of performing Volumetric Karl Fischer titrations withan electrometric end-point detector can be used in this method.6.2 Microlitre Syringe,10 L.6.3 Pipette,10 mL.6.4 Analytical Balance,capable of weighing to the nearest0.0001 g accurately.7.Reagents and Materials7.1 Purity of ReagentsReagent grade che