ASTM_D_7716_-_11a.pdf

Designation:D771611aStandard Test Method forDetermination of Residual Methanol in Glycerin by GasChromatography1This standard is issued under the fixed designation D7716;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 for the quantitative determi-nation of residual methanol in glycerin by gas chromatography.The range of detection for residual methanol is 0.02 to 0.60mass%.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 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:2D1193 Specification for Reagent WaterD7640 Specification for Engine Coolant Grade GlycerinE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE355 Practice for Gas Chromatography Terms and Relation-shipsE594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid ChromatographyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 DefinitionsThis test method makes reference to manycommon gas chromatographic procedures,terms,and relation-ships.Detailed definitions can be found in Practices E355 andE594.4.Summary of Test Method4.1 The sample is analyzed by headspace gas chromatogra-phy.Calibration is achieved by the use of external standards ofmethanol in water.5.Significance and Use5.1 Methanol content reflects the quality of glycerin for useas an engine coolant.The current specification for the maxi-mum methanol content is 0.1%weight to weight(w/w).6.Apparatus6.1 Chromatographic SystemSee Practice E355 for spe-cific designations and definitions.The gas chromatograph(GC)system shall be capable of operating at the conditions given inTable 1.6.2 Autosampler system,Gerstel multipurpose samplerMPS-23or equivalent.This method can also be run manually.6.3 Column,open tubular column with polyethylene glycol(PEG)bonded and cross-linked phase internal coating.Thecolumn should have an upper temperature limit of 260C.Acolumn 30 m in length,with an internal diameter of 0.32 mm,and a 1.0-m film thickness has been found satisfactory.Anycolumn with equivalent or better chromatographic efficiencyand selectivity can be used.6.4 Electronic Data Acquisition SystemA computer ca-pable of providing real-time graphic and digital presentation ofthe chromatographic data is recommended for use.Peak areasand retention times shall be measured by computer or elec-tronic integration(integrator).7.Reagents and Materials7.1 Purity of ReagentsReagent-grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society where1This test method is under the jurisdiction of ASTM Committee D15 on EngineCoolants and Related Fluids and is the direct responsibility of SubcommitteeD15.93 on Research and Long Range Planning.Current edition approved Oct.1,2011.Published November 2011.Originallyapproved in 2011.Last previous edition approved in 2011 as D7716 11.DOI:10.1520/D7716-11A.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.3The sole source of supply of the apparatus known to the committee at this timeis GERSTEL GmbH&Co.KG,Eberhard-Gerstel-Platz 1,45473 Mlheim an derRuhr,Germany.If you are aware of alternative suppliers,please provide thisinformation to ASTM International Headquarters.Your comments will receivecareful consideration at a meeting of the responsible technical committee,whichyou may attend.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 such specifications are available.4Other grades may be usedprovided it is first ascertained that the reagent is of sufficientpurity to permit its use without lessening the accuracy of thedetermination.7.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water as definedby Type II of Specification D1193.7.3 Methanol,reagent grade.7.4 Glycerin,meeting Specification D7640.7.5 Carrier gas,hydrogen or helium of high purity.Addi-tional purification is recommended by the use of molecularsieves or other suitable agents to remove water,oxygen,andhydrocarbons.Available pressure shall be sufficient to ensu