ASTM_D_5508_-_16.pdf

Designation:D550816Standard Test Method forDetermination of Residual Acrylonitrile Monomer in Styrene-Acrylonitrile Copolymer Resins and Nitrile-ButadieneRubber by Headspace-Capillary Gas Chromatography(HS-CGC)1This standard is issued under the fixed designation D5508;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.Scope*1.1 This test method covers the determination of the re-sidual acrylonitrile(RAN)content in nitrile-butadiene rubbers(NBR),styrene-acrylonitrile(SAN)copolymers,and rubber-modified acrylonitrile-butadiene-styrene(ABS)resins.1.2 Any components that can generate acrylonitrile in theheadspace procedure will constitute an interference.The pres-ence of 3-hydroxypropionitrile in latices limits this procedureto dry rubbers and resins.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 and health practices and determine the applica-bility of regulatory limitations prior to use.Specific precau-tionary statements are given in 6.3 and 6.4.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Summary of Test Method3.1 Two dispersions(in o-dichlorobenzene)are preparedand sealed in headspace vials for each polymer;one vialcontains the polymer in solvent while the second vial containsthe polymer,solvent,plus a known standard addition ofacrylonitrile(AN).Both vials are agitated for a specified timeunder ambient conditions.After agitation,the vials are ther-mally equilibrated in a constant-temperature bath.3.2 After completion of the timed equilibration,an aliquotof the heated headspace gas from each vial is injected into acapillary gas-chromatographic column using an automatedinjection system.The capillary column will provide the chro-matographic resolution necessary to isolate the AN from othervolatiles potentially present.The AN response is measuredusing a nitrogen-specific detector(NPD).The raw data signalis converted to a relative RAN concentration through astandard addition calculation.4.Significance and Use4.1 A measurement of the residual acrylonitrile in nitrilerubbers(NBR),styrene-acrylonitrile copolymers or ABS ter-polymers will determine the polymers suitability for variousapplications.4.2 Under optimum conditions,the minimum level of de-tection of RAN in NBR,SAN,or ABS terpolymers is approxi-mately 50 ppb.5.Apparatus5.1 Gas Chromatograph,equipped with a nitrogen-phosphorus specific detector,backflush valve(see Fig.1),splitinjector,and capable of accepting megabore(0.53 mm insidediameter)fused silica capillary columns.Detector make-up gasis required.NOTE2The use of a backflush configuration will provide foroperating advantages,but its use is optional.Chlorinated solvents quenchthe alkali bead in a nitrogen-phosphorous detector,producing a loss ofsignal.While the bead(signal)will recover as the solvent evacuates thedetector,repeated quenching during a multi-run sequence may produceinstabilities in the signal(and precision)over the sequence period.5.2 Automated Headspace Sampler,shall have a thermost-atted sample tray capable of 90C heating with constantheating times.Automated sampling of the headspace gas in thesample vials via a heated,constant-volume sample loop or1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods andSection D20.70.02 on Chromatography.Current edition approved Sept.1,2016.Published September 2016.Originallyapproved in 1994.Last previous edition approved in 2009 as D5508-94a(2009)1.DOI:10.1520/D5508-16.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 pressure balancing sampling mechanism is required.Conductsampling to the gas chromatograph by means of a heatedtransfer line of minimum dead volume.5.3 Fused Silica Porous-Layer-Open-Tubular(PLOT)Cap-illary Column,30 m 0.53 mm inside diameter.NOTE3The column should be cut so as to have a 3 m section for thepre-column(Column 1)and a 27-m section for the analytical column(Column 2).5.4 Variable Restrictor.5.5 Data-Recording DeviceA strip-chart r