ASTM_D_3834_-_93.pdf

Designation:D 3834 93Standard Test Method forPurity of Vinyl Chloride Monomer by Gas Chromatography1This standard is issued under the fixed designation D 3834;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 The general availability of gas chromatography in prac-tically every laboratory and the inherent sensitivity in thedetection of trace constituents indicate that the techniquewould qualify as a standard test method.With this one-steptechnique,impurities can be determined in a range thatincludes major constituents and parts per million impurities.1.2 Inherent in this test method is the limitation that theimpurities must be volatile.Resolution of some of the indi-vidual impurities may be limited by the column selected.Theuse of several different types of columns may be necessary ifthe ultimate in resolution is required.A single column willnormally give the required degree of separation.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address all of thesafety problems,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.Specific hazardsstatements are given in Section 8.NOTE1There is no similar or equivalent ISO standard.2.Referenced Documents2.1 ASTM Standards:E 260 Practice for Packed Column Gas Chromatography2E 355 Practice for Gas Chromatography Terms and Rela-tionships23.Terminology3.1 DefinitionsAll terms and practices used in this testmethod are in accordance with Practices E 260 and E 355.4.Summary of Test Method4.1 Conventional gas chromatographic techniques are used.A small sample is injected into a gas chromatographic columnpacked with a liquid-coated solid support or porous polymerbeads.Passing over the support in a stream of helium,thesample is separated into its components,which are detected bya standard sensing device.The signal is recorded to indicate therelative concentration of a component and the retention time.5.Significance and Use5.1 Vinyl chloride monomer(Warning:see 8.1)must bevery pure to produce high-quality polymers with desirableappearance,stability,and generally desirable physical proper-ties.Even trace concentrations of certain impurities,for ex-ample,conjugated dienes,interfere with the mechanism ofpolymerization.This test method is applied accordingly toprocess and quality control.5.2 It is expected that this test method will be suitable forspecifications,manufacturing control,and research and devel-opment.However,other specifications may be required todefine a product completely.6.Interferences6.1 Retention times are dependent upon a large number ofvariables associated with the composition,length,and diameterof the column,the size of the sample,the temperature of thecolumn,the carrier gas flow rate,and the temperature of theinjection port.It is therefore quite possible to have twocomponents or impurities with identical retention times.Onlyby changing columns or column conditions can these concur-rent peaks be resolved.6.2 Temperature programming,as recommended in this testmethod,must be precisely controlled to obtain reproducibleretention times and reliable identification of constituents.6.3 A given species has only one peak associated with it foridentification;therefore,identification from that one peak by itsretention time alone is risky unless coupled with other infor-mation.Such information might be obtained with a massspectrometer or chemical tests for functional groups.7.Apparatus7.1 Many commercial instruments are suitable for this test;however,there are two basic requirements.The detectors mustbe equivalent in sensitivity to hydrogen flame ionizationdetectors and the column oven must be designed for tempera-ture programming in the range from 40 to 150C.7.2 The basic equipment includes:injection ports,columns,column ovens,detectors,a recorder,a suitable attenuatingdevice for keeping the peaks on scale,a temperature program-ming unit,and a syringe or liquid-sampling valve for injectionof microlitres of sample onto the columns.7.3 Dual columns are recommended for stable baselines.7.4 An electronic or mechanical integrator is recommended1This test method is under the jurisdiction ofASTM Committee D-20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Feb.15,1993.Published April 1993.Originallypublished as D 3834 80.Last previous edition D 3834 80(1987).2Annual Book of ASTM Standards,Vol 14.01.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMNOTICE