1、Designation: D3749 12Standard Test Method forResidual Vinyl Chloride Monomer in Poly(Vinyl Chloride)Resins by Gas Chromatographic Headspace Technique1This standard is issued under the fixed designation D3749; the number immediately following the designation indicates the year oforiginal adoption or,
2、 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 is suitable for determining the residualvinyl chloride monomer
3、 (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 copolymer resin if the Hen
4、rys 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 D4443 orTest Method D3680 for these materials.1.4 This test method is proposed as an alternative to EPAMethod 107 for determination of vinyl
5、 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 appro-priate safety and
6、health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1This standard and ISO 6401 address the same subject matter,but differ in technical content.2. Referenced Documents2.1 ASTM Standards:2D3680 Test Method for Residual Vinyl Chloride MonomerContent of Poly(Vi
7、nyl Chloride) Resins, Compounds, andCopolymers by Solution Injection Technique (Withdrawn2005)3D4443 Test Method for Determining Residual Vinyl Chlo-ride Monomer Content in PPB Range in Vinyl ChlorideHomo- and Co-Polymers by Headspace Gas Chromatog-raphyD4526 Practice for Determination of Volatiles
8、in Polymersby Static Headspace Gas ChromatographyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 Federal Standards:Environmental Protection Agency Method 107 Determina-tion of Vinyl Chloride Content of In-Process Waste-WaterSamples, and Vinyl Chlor
9、ide Content of Poly(Vinyl Chlo-ride) Resin, Slurry, Wet Cake, and Latex Samples429 CFR 1919.1017 Vinyl Chloride for Regulated Levels ofExposure52.3 ISO Standard:ISO 6401 Determination of Residual Vinyl Chloride Mono-mer in Homopolymers and Copolymers by Gas Chroma-tography63. Terminology3.1 Acronyms
10、: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.1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of
11、Subcommittee D20.70 on Analytical Methods.Current edition approved Oct. 1, 2012. Published November 2012. Originallyapproved in 1978. Last previous edition approved in 2008 as D3749 - 08. DOI:10.1520/D3749-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custom
12、er Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from United States Environmental Protection Agency (EPA),
13、 ArielRios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460, http:/www.epa.gov.5Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.6Available from American National Standards Institu
14、te (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.*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 States13.1.6 PIDPhotoionization detector.3.1.7 HEDHa
15、ll electroconductivity detector.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
16、rapidly, provided that thetemperature 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 t
17、hat ispacked with a liquid-coated solid support or porous polymerbeads. 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 isd
18、etected by a standard sensing device. The signal is recorded toindicate the relative concentration of the VCM and its retentiontime.4.3 Refer to Practice D4526 for additional information onheadspace gas chromatography.5. Significance and Use5.1 Poly(vinyl chloride) resins must contain a minimumpossi
19、ble amount of unreacted, or free, VCM.5.2 This test method provides a measure of RVCM which issuitable for manufacturing control or specification acceptancepurposes.5.3 Under optimum conditions, a lower level of detection of2 ppm by volumeVCM can be detected in the headspace vapor.Using a 4-g sample
20、, this is equivalent to about 0.02 ppm bymass RVCM in the PVC resin.6. Interferences6.1 Normally, the vapor above PVC resin will contain onlyair, VCM, water, small amounts of catalyst breakdownproducts, and any solvents or comonomers used in polymer-ization. Impurities in the 0 to 1000-ppm range wil
21、l generallyhave only a very small influence on this equilibrium relation-ship.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), ph
22、otoionization detector (PID), or a Hallelectroconductivity detector (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 Chroma
23、tographic Column, 80/100-mesh7in 1-m by3.2-mm stainless steel tubing.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
24、to be modified.7.3 Integrator, or computerized data system for peak mea-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 com
25、puter.8. Reagents and Materials8.1 StandardsCylinders of known concentrations 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 shall be used for detection limits
26、less than 2 ppm.8.2 Nitrogen, or helium, oxygen-free, carrier gas 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
27、 ppm levels. Venting or purging of VCM mixtures must beheld to a minimum and shall 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, ho
28、t vials, etc.Handle all electrical connections with care.9.3 Vials shall 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
29、 and Storage10.1 Weigh and seal resin samples in the headspace vials inaccordance with 12.1 as soon as possible, not to exceed 24 h.10.2 It is possible to store resins in the sealed headspacevials for up to four weeks without loss of VCM if they areanalyzed without being reopened.11. Preparation of
30、Gas Chromatograph11.1 Connect carrier gas and detector gas cylinders to thechromatograph with the recommended filters and regulators asrequired by the manufacturer.7Porapak Q, available from Supelco, Inc., Supelco Park, Bellefonte, PA16823 0048, has been found to be satisfactory for this purpose.D37
31、49 12211.2 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 at 150C. After conditioning, cool andconnect the column exit to the detector.NOTE 4Se
32、e 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 Set other chromatograph controls as necessary toobtain the desired resolution and sen
33、sitivity for the instrumentused, as follows:11.5.1 Analysis time (and backflush time, if used) asrequired, depending on the location time of VCM.11.5.2 Detector, recorder, and integrator sensitivities asneeded to detect theVCM levels in the samples. Ensure that thesystem is capable of producing a me
34、asurement for a 50-ppmvinyl chloride standard that is at least 10 times 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
35、60 and250 s after injection. Record the system head pressure underthose 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 t
36、he sample line from the cylinder into the hoodprior to filling the vials. (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
37、the tube to minimizemixing air with the standard gas in the vial. Purge 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
38、 Inject 100 L of organic-free water into the vial witha burr-free, 24-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 wi
39、th the samples in exactlythe same manner and at the same detector range.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 turnt
40、able in the orderrequired for the instrument in use.13.3 Condition each 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 rem
41、oval from the turntable. (See 9.3.)14. Calculation14.1 Calculate the 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
42、i.14.2 Calculate the average response factor for the sixstandards. (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:Cvcm5AsPaRfT1FMvVgmR1KpT2G(2)where:Cvcm= concen
43、tration of residual vinyl chloride in resin,ppm by weight,As= VCM peak 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 vi
44、al 5 m!/density of polymer! (3)where:m = mass of sample, g,R = gas constant (62 360 cm3 mm/mol K),Kp= Henrys Law constant (7.52 106/mm Hg for PVChomopolymer at 90C), andT2= equilibration temperature (363 K).NOTE 5This equation is best solved using a programmable calculatoror computer.14.4 The genera
45、lized equation can be simplified for aparticular set of conditions, assuming the following conditionsare met:14.4.1 A sample is a PVC homopolymer containing lessthan 1 % water (Kp=6.52106).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
46、.4.4 Ambient pressure is 750 6 10 mm Hg (Pa= 750).14.4.5 Equilibration temperature is 90 6 1C (T2= 363).D3749 12314.5 The equation in 14.3 under the conditions in 14.4.1through 14.4.5 reduces toCvcm52.54 AsRf0.0205m10.0024 (4)15. Report15.1 Report the calculated residual vinyl chloride concen-tratio
47、ns to two significant figures in parts per million by weight(mg/kg) of dry resin.16. Precision and Bias816.1 PrecisionValues were determined in accordance withPractice E691 using data from an interlaboratory evaluation ofthree materials analyzed in duplicate (same day) by sixlaboratories:Average RVC
48、M (g/g)400 12 to 18Withinlaboratory (Sr)21.5 0.62Betweenlaboratories(SR)53.3 0.9116.1.1 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 standard oralternative test metho
49、d, there is no estimate of bias.17. Keywords17.1 gas chromatography; headspace gas chromatography;poly(vinyl chloride); vinyl chloride monomerSUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue (D3749 - 08)that may impact the use of this standard. (October 1, 2012)(1) Removed year reference from ISO standard in Note 1. (2) Removed year reference from ISO standard in section 2.3.Committee D20 has identified the location of selected changes to this standard since the last
