1、Designation: D 3749 95 (Reapproved 2002)Standard Test Method forResidual Vinyl Chloride Monomer in Poly(Vinyl Chloride)Resins by Gas Chromatographic Headspace Technique1This standard is issued under the fixed designation D 3749; the number immediately following the designation indicates the year ofo
2、riginal 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 This test method is suitable for determining the residualvi
3、nyl chloride monomer (RVCM) content of poly(vinyl chlo-ride) (PVC) homopolymer and copolymer resins for uses otherthan food contact. The range for this test, based on interlabo-ratory evaluation, is from 0.1 to 400 ppm RVCM.1.2 This test method can be adapted to determinations ofRVCM in a PVC copoly
4、mer resin if the Henrys Law constantat 90C for that copolymer is known.1.3 This test method cannot be used for polymer in fusedforms, such as cubes or sheets. Refer to Test Method D 4443 orTest Method D 3680 for these materials.1.4 This test method is proposed as an alternative to EPAMethod 107 for
5、determination of vinyl chloride monomers indry-resin samples.1.5 The values stated SI units are to be regarded as thestandard.1.6 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 ap
6、pro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1This test method is similar to ISO 6401-1985 in title only. Thetechnical content is significantly different.2. Referenced Documents2.1 ASTM Standards:D 3680 Test Method for Residual V
7、inyl Chloride MonomerContent of Poly(Vinyl Chloride) Resins, Compounds, andCopolymers by Solution Injection Technique2D 4443 Test Method for Analysis for Determining ResidualVinyl Chloride Monomer Content in PPB Range in VinylChloride Homo- and Co-Polymers by Headspace GasChromatography3D 4526 Pract
8、ice for Determination of Volatiles in Polymersby Headspace Gas Chromatography3E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method42.2 Federal Standards:Environmental Protection Agency Method 107 Determinationof Vinyl Chloride Content of In-Process Waste-
9、WaterSamples, and Vinyl Chloride Content of Poly(Vinyl Chlo-ride) Resin, Slurry, Wet Cake, and Latex Samples529 CFR 1919.1017 Vinyl Chloride for Regulated Levels ofExposure62.3 ISO Standard:ISO 6401-1985 Determination of Residual Vinyl ChlorideMonomer in Homopolymers and Copolymers by GasChromatogra
10、phy73. Terminology3.1 Acronyms:Acronyms:3.1.1 VCMVinyl chloride monomer.3.1.2 RVCMResidual vinyl chloride monomer.3.1.3 PVCPoly(vinyl chloride).3.1.4 OSHAOccupational Safety and Health Agency.3.1.5 FIDFlame ionization detector.3.1.6 PIDPhotoionization detector.3.1.7 HEDHall electroconductivity detec
11、tor.3.1.8 MHEMultiple headspace extraction.4. Summary of Test Method4.1 The basis for this test method relates to the vaporequilibrium that is established between RVCM, PVC resin, andair in a closed system. The RVCM in a PVC resin willequilibrate in a closed vessel quite rapidly, provided that thete
12、mperature of the PVC resin is maintained above the glasstransition temperature of that specific resin type.4.2 After sample equilibration, conventional gas chromato-graphic (GC) techniques are used. A constant amount ofsample headspace vapor is injected into a GC column that is1This test method is u
13、nder the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved June 15, 1995. Published August 1995. Originallypublished as D 3749 78. Last previous edition D 3749 93. This edition includesrevisions to Sec
14、tion 14.2Annual Book of ASTM Standards, Vol 06.03.3Annual Book of ASTM Standards, Vol 08.03.4Annual Book of ASTM Standards, Vol 14.02.5Available from the U.S. Environmental Protection Agency, Research TrianglePark, NC 27711.6Available from the Superintendent of Documents, Government Printing Office,
15、Washington, DC 20402.7Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.packed with a liquid-coated solid support or porous polymerbeads
16、. Sample injection is accomplished by available commer-cial automatic equipment. Passing through the column in astream of carrier gas, the vinyl chloride monomer (VCM) isseparated from other components which may be present and isdetected by a standard sensing device. The signal is recorded toindicat
17、e the relative concentration of the VCM and its retentiontime.4.3 Refer to Practice D 4526 for additional information onheadspace gas chromatography.5. Significance and Use5.1 Poly(vinyl chloride) resins must contain a minimumpossible amount of unreacted, or free, VCM.5.2 This test method provides a
18、 measure of RVCM which issuitable for manufacturing control or specification acceptancepurposes.5.3 Under optimum conditions, a lower level of detection of2 ppm by volume VCM can be detected in the headspace vapor.Using a 4-g sample, this is equivalent to about 0.02 ppm bymass RVCM in the PVC resin.
19、6. Interferences6.1 Normally, the vapor above PVC resin will contain onlyair, VCM, water, small amounts of catalyst breakdown prod-ucts, and any solvents or comonomers used in polymerization.Impurities in the 0 to 1000-ppm range will generally have onlya very small influence on this equilibrium rela
20、tionship.6.2 Any material that elutes from the chromatographiccolumn at approximately the same time as vinyl chloride willcause high RVCM results.7. Apparatus7.1 Gas Chromatograph, equipped with a flame ionizationdetector (FID), photoionization detector (PID), or a Hallelectroconductivity detector (
21、HED) and capable of heating,sampling, and analyzing the headspace vapors contained insealed vials.NOTE 2Automatic backflushing capability may be a desirable optionfor some copolymer samples to reduce the time of analysis.7.2 Chromatographic Column, 80/100-mesh8in 1-m by3.2-mm stainless steel tubing.
22、NOTE 3Any column that will resolve VCM from any interferencesand will elute VCM between 1 and 4 min using a system pressure of 100to 150 kPa is satisfactory. If an alternate column is used, the chromato-graphic conditions may need to be modified.7.3 Integrator, or computerized data system for peak m
23、ea-surements.7.4 Balance, capable of weighing to 61 % of sampleweight.7.5 Accessories, for headspace samples, including vials,septa, seals, and crimper.7.6 Syringe, 100-L capacity, 24-gage needle.7.7 Programmable Calculator, or computer.8. Reagents and Materials8.1 StandardsCylinders of known concen
24、trations of vinylchloride in nitrogen gas. Nominal concentrations of 5, 50, and500 ppm by volume (vppm) are needed, unless multipleheadspace extraction (MHE) is used. Lower concentrationstandards may be desirable for a detection limit less than 2ppm.8.2 Nitrogen, or helium, oxygen-free, carrier gas
25、for chro-matograph.8.3 Hydrogen, prepurified for FID detector.8.4 Air, breathing grade, for FID detector.9. Hazards9.1 Vinyl chloride monomer is a cancer-suspect agent andmust never be released to the laboratory atmosphere, even atlow ppm levels. Venting or purging of VCM mixtures must beheld to a m
26、inimum and should be vented into a properlyfunctioning fume hood. Refer to 29 CFR 1919.1017 forregulated levels of exposure.9.2 Be careful not to come into contact with heated parts ofthe chromatograph, such as the detector, column, hot vials, etc.Handle all electrical connections with care.9.3 Vial
27、s should be vented to atmospheric pressure afteranalysis and prior to removal from the thermostatted turntable.A hypodermic needle connected to a syringe containing afreshly activated charcoal is suitable for this operation.10. Sampling and Storage10.1 Weigh and seal resin samples in the headspace v
28、ials inaccordance with 12.1 as soon as possible, not to exceed 24 h.10.2 Resins may be stored in the sealed headspace vials forup to four weeks without loss of VCM if they are analyzedwithout being reopened.11. Preparation of Gas Chromatograph11.1 Connect carrier gas and detector gas cylinders to th
29、echromatograph with the recommended filters and regulators asrequired by the manufacturer.11.2 Establish correct control of the thermostatted head-space unit.11.3 Install the chromatographic column connected to theinjector only. Establish an appropriate flow rate, and conditionthe column overnight a
30、t 150C. After conditioning, cool andconnect the column exit to the detector.NOTE 4See Appendix XI for recommendations for particular instru-ment parameters.11.4 Set the pressure and flow of hydrogen and air to thedetector in accordance with the manufacturers recommenda-tions. Ignite the flame.11.5 S
31、et other chromatograph controls as necessary toobtain the desired resolution and sensitivity for the instrumentused, as follows:11.5.1 Analysis time (and backflush time, if used) as re-quired, depending on the location time of VCM.11.5.2 Detector, recorder, and integrator sensitivities asneeded to d
32、etect the VCM levels in the samples. The systemshould be capable of producing a measurement for a 50-ppm8Porapak Q, available from Supelco, Inc., Supelco Park, Bellefonte, PA16823 0048, has been found to be satisfactory for this purpose.D 3749 95 (2002)2vinyl chloride standard that is at least 10 ti
33、mes the standarddeviation of the system background noise level.11.6 Establish the proper combination of oven temperatureand carrier flow rate to obtain a resolved, symmetrical VCMpeak eluting from the chromatographic column between 60 and250 s after injection. Record the system head pressure underth
34、ose conditions.12. Calibration12.1 Prepare calibration standards by filling vials with theVCM in nitrogen standards, rapidly seating the septum, sealingwith the aluminum retainer, and injecting 100 L of distilledwater.12.1.1 Purge the sample line from the cylinder into the hoodprior to filling the v
35、ials. (Use 3.2-mm stainless steel, not rubberor plastic, sample lines.)12.1.2 With a flow rate of 500 to 1000 cm3/min, place theend of the tubing into a vial to the bottom. Position the septumon top of the vial, pressing it against the tube to minimizemixing air with the standard gas in the vial. Pu
36、rge each vialwith the standard for at least 60 s.12.1.3 Gradually slide the tube to the top of the vial,simultaneously sealing the vial with the septum as the tube iswithdrawn.12.1.4 Crimp an aluminum retainer over the septum.12.1.5 Inject 100 L of organic-free water into the vial witha burr-free, 2
37、4-gage needle to ensure uniformity of water vaporcontribution to the vial pressure.12.2 For each series of samples to be tested, prepare twovials each of the three standard gases. These calibrationstandards will be analyzed along with the samples in exactlythe same manner and at the same detector ra
38、nge.13. Procedure13.1 Sample PreparationAdd 0.2 to 4 g 6 10 % of resinto a tared vial. Record exact weight to 61 %. Add by pipet, 2drops of organic-free water, and immediately seal the vial.13.2 Place the vials in the analyzer turntable in the orderrequired for the instrument in use.13.3 Condition e
39、ach vial in the 90C bath for at least 1 h,but no more than 5 h, before analyzing.13.4 Analyze the headspace in each equilibrated vial todetermine the VCM peak area.13.5 Depressurize each vial with a needle after analysisprior to removal from the turntable. (See 9.3.)14. Calculation14.1 Calculate the
40、 individual response factors for the stan-dards as follows:Rfi5 Ai!/Ci! (1)where:Rfi= response factor from standard in Vial i,Ai= VCM peak area from Vial i, counts, andCi= concentration of VCM, ppm by volume, in standardgas in Vial i.14.2 Calculate the average response factor for the sixstandards. (
41、Compare the factors to each other and previouslydetermined factors. Investigate any large differences.)14.3 The generalized headspace equation for the VCM/PVCresin system is as follows:Cvcm5AsPaRfT1FMvVgmR1 KpT2G(2)where:Cvcm= concentration of residual vinyl chloride in resin,ppm by weight,As= VCM p
42、eak area in sample, counts,Pa= atmospheric pressure, mm Hg,Rf= average response factor, counts per vppm,T1= laboratory temperature, K,Mv= molecular weight of VCM (62.5 g/mole), andVg= free vapor volume of vial, cm3,volume of empty vial 5m!/density of polymer! (3)where:m = mass of sample, g,R = gas c
43、onstant (62 360 cm3 mm/mol K),Kp= Henrys Law constant (7.52 3 106/mm Hg forPVC homopolymer at 90C), andT2= equilibration temperature (363 K).NOTE 5This equation is best solved using a programmable calculatoror computer.14.4 The generalized equation can be simplified for aparticular set of conditions
44、, assuming the following conditionsare met:14.4.1 A sample is a PVC homopolymer containing lessthan 1 % water (Kp= 6.52 3 106).14.4.2 Vials have a total capacity of 23 6 1cm3(Vg= 20.5).14.4.3 Laboratory temperature is 22 6 2C (T1= 295).14.4.4 Ambient pressure is 750 6 10 mm Hg (Pa= 750).14.4.5 Equil
45、ibration temperature is 90 6 1C (T2= 363).14.5 The equation in 14.3 under the conditions in 14.4.1through 14.4.5 reduces toCvcm52.54 AsRf0.0205m1 0.0024 (4)15. Report15.1 Report the calculated residual vinyl chloride concen-trations to two significant figures in parts per million by weight(mg/kg) of
46、 dry resin.16. Precision and Bias916.1 PrecisionValues were determined in accordancewith Practice E 691 using data from an interlaboratory evalu-ation of three materials analyzed in duplicate (same day) by sixlaboratories:Average RVCM (g/g)400 12 to 18Within laboratory (Sr) 21.5 0.62Between laborato
47、ries (SR) 53.3 0.919Supporting data are available from ASTM Headquarters. Request RR:D20 1140.D 3749 95 (2002)316.1.1 Another sample containing an average RVCM levelof 0.13 ppm gave within-laboratory precision of 0.02 andbetween-laboratory precision of 0.1.16.2 BiasIn the absence of any absolute sta
48、ndard oralternative test method, there is no estimate of bias.17. Keywords17.1 gas chromatography; headspace gas chromatography;poly(vinyl chloride); vinyl chloride monomerASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned
49、in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comm
