ASTM_D_7252_-_06_2011e1.pdf

Designation:D725206(Reapproved 2011)1Standard Test Method forPolyurethane Raw Materials:Determination of Monomer andIsomers in Isocyanates1This standard is issued under the fixed designation D7252;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.1NOTEReapproved with editorial changes in September 2011.1.Scope1.1 This test method determines the percent by weight ofmonomeric isomers and total monomer in crude or modifiedisocyanates.The test method is applicable to methylene di(phe-nylisocyanate)(MDI)and polymeric(meththylene phenyliso-cyanate)(PMDI).(See Note 1.)1.2 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.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsE682 Practice for Liquid Chromatography Terms and Rela-tionshipsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 For definitions of terms used in these test methods seeTerminology D883.4.Summary of Test Method4.1 The sample is reacted(derivatized)with methanol toform a mixture of methyl urethanes.The urethanes mixture isthen separated by normal phase high performance liquidchromatography(HPLC).The separated,derivatized isomersare quantified through the use of an internal standard.5.Significance and Use5.1 This test method can be used for research or for qualitycontrol to characterize isocyanates used in polyurethane prod-ucts.6.Apparatus6.1 High Performance Liquid Chromatograph,consistingof:6.1.1 Binary(or greater)solvent pump,capable of main-taining a pulse-free flow rate of 1-3 millilitres per minute6.1.2 Sample injector,automatic or manual,capable ofreproducibly injecting a 2 microlitre volume6.1.3 Column heater,capable of maintaining a temperatureof 30 6 0.2C6.1.4 UV detector,capable of measurements at 235 nm.6.1.5 Chart recorder or Data system,capable of peak areaintegration.6.2 HPLC analytical column,250 mm by 4.6 mm by 5 mcyano stationary phaseNOTE2Other chromatographic columns can be used provided it isascertained that similar chromatographic performance is obtained.6.3 Magnetic Stirring Hotplate.7.Reagents and Materials7.1 Purity of ReagentsReagent-grade chemicals are to 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,wheresuch specifications are available.Other grades can be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.1.1 Acetanilide,99.9%purity,to be used as an internalstandard.7.1.2 Acetonitrile,dry.Dry this and reagents below overmolecular sieve for twenty-four hours.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on Cellular Materials-Plastics and Elastomers.Current edition approved Sept.1,2011.Published October 2011.Originallyapproved in 2006.Last previous edition approved in 2006 as D7252-06.DOI:10.1520/D7252-06R11E01.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.1.3 Ethanol,dry.Use of ethanol denatured with methanol(such as SDA-30)can be used if more readily available.7.1.4 Hexane,dry.7.1.5 Methanol,dry.7.1.6 Eluent solution,Mix 1:1 by volume of dry methanoland ethanol.7.1.7 Derivatization solution,Dissolve 0.20 g of acetanilidein 1 L of dry methanol.8.Sampling8.1 Since organic isocyanates react with atmosphericmoisture,take special precautions in sampling.Usual samplingmethods,even when conducted rapidly,can cause contamina-tion of the sample with insoluble urea.Therefore,blanket thesample with dry air or nitrogen at all times.(WarningManydiisocyanates are known or suspected sensitizers.Over-exposure to diisocyanates can lead to adverse health effectswhich include the development of occupational asthma andother respiratory,skin and eye effects.Engineering controlsand/or personal protective equipment,including respiratory,skin and eye protection,are to be used when there is a potentialfor over-exposure to diisocyanates.The product suppliersMaterial Safety Data Sheet(MSDS)provides more detailedinformation ab