ASTM_D_7637_-_10_2021.pdf

Designation:D763710(Reapproved 2021)Standard Test Method forDetermination of Glycerin Assay by Titration(Sodium MetaPeriodate)1This standard is issued under the fixed designation D7637;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 provides the quantitative determinationof glycerin by the titrimetric method.It is applicable to allglycerin or glycerin/water mixtures 75%.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard may involve hazardous materials,operations,and equipment.This standard does not purport toaddress all of the safety concerns associated with its use.It isthe responsibility of the user of this standard to consult theestablished and appropriate safety,health,and environmentalpractices and determine the applicability of regulatory limita-tions prior to use.Specific precautions are listed in Section 8.1.4 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 WaterD4725 Terminology for Engine Coolants and Related FluidsE177 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 Other Standards:The United States Pharmacopoeia 31 Glycerin Monograph Assay Method3AOCS Official Method EA 6-94(Replaces AOCS EA 6-51),Determination of Crude Glycerin,Titrimetric Method4BS 5711:Part 3,1979 Sampling and Test for Glycerol-Determination of Glycerol Content53.Terminology3.1 Definitions:3.1.1 glycerinpropane-1,2,3-triol,C3H5(OH)3(alsoknownasglycerine),1,2,3-propanetriol,1,2,3-trihydroxypropane,glyceritol,glycyl alcohol,glycerol.CAS#56-81-5.3.1.2 SMPSodium Meta Periodate.3.1.3 For other definitions of terms used in this test method,refer to Terminology D4725.4.Significance and Use4.1 This test method is based on the cold oxidation of theglycerol by sodium metaperiodate in a strong acidic medium.Formaldehyde and formic acid are produced in this reactionand the latter is used to measure the glycerol content bytitration with standard sodium hydroxide solution,to a pH 8.16 0.1.The glycerol content is expressed as a percentage(m/m).CH2OH2 CHOH2 CH2OH12 NaIO4(1)HCOOH12 HCHO12 NaIO31H2O4.2 InterferencesThe glycerin sample should be free oforganic compounds with more than two hydroxyl groups onadjacent carbon atoms(for example,sugars,glycols).Thesetypes of compounds may produce formic acid which interfereswith the determination of the glycerol content.1This test method is under the jurisdiction of ASTM Committee D15 on EngineCoolants and Related Fluids and is the direct responsibility of SubcommitteeD15.04 on Chemical Properties.Current edition approved Sept.1,2021.Published September 2021.Originallyapproved in 2010.Last previous edition approved in 2015 as D763710(2015).DOI:10.1520/D7637-10R21.2For 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.Pharmacopeial(USP),12601 Twinbrook Parkway,Rockville,MD 20852-1790,http:/www.usp.org.4Available from American Oil Chemists Society(AOCS),2710 S.Boulder,Urbana,IL 61802-6996,http:/www.aocs.org.5Available from The British Standards Institution(BSI),389 Chiswick High Rd.,London W4 4AL,U.K.,http:/.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.15.Apparatus5.1 Burette50 mL“Type A”unit that can deliver 30 dropsper mL and calibrated to meet the National Institute ofStandards and Technology(NIST)standards.NOTE1 It is critical that all glassware be“Type A”and thoroughlycleaned before use as dirty glassware will impact the analysis results.5.2 pH meter,fitted with glass electrode.NOTE2The pH meter should be standardized with a minimum of twobuffer solutions at 10.0 and 7.0.(See 7.12.)5.3 Stirrerpreference should be given to a magnetic stir-rer.In this case,check that it does not influence the pH meter.6.Purity of Reagents and