1、Designation: D3749 12D3749 13Standard 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 adop
2、tion 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 is suitable for determining the residual vinyl chlorid
3、e monomer (RVCM) content of poly(vinyl chloride)(PVC) homopolymer and copolymer resins for uses other than food contact. The range for this test, based on interlaboratoryevaluation, is from 0.1 to 400 ppm RVCM.1.2 This test method can be adapted to determinations of RVCM in a PVC copolymer resin if
4、the Henrys Law constant at 90Cfor that copolymer is known.1.3 This test method cannot be used for polymer in fused forms, such as cubes or sheets. Refer to Test Method D4443 or TestMethod D3680 for these materials.1.4 This test method is proposed as an alternative to EPAMethod 107 for determination
5、of vinyl chloride monomers in dry-resinsamples.1.5 The values stated SI units are to be regarded as the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate sa
6、fety and health practices and determine the applicability of regulatorylimitations 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 Monomer Content o
7、f Poly(Vinyl Chloride) Resins, Compounds, andCopolymers by Solution Injection Technique (Withdrawn 2005)3D4443 Test Method for Determining Residual Vinyl Chloride Monomer Content in PPB Range in Vinyl Chloride Homo- andCo-Polymers by Headspace Gas ChromatographyD4526 Practice for Determination of Vo
8、latiles in Polymers by Static Headspace Gas ChromatographyE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2.2 Federal Standards:Environmental Protection Agency Method 107 Determination of Vinyl Chloride Content of In-Process Waste-Water Samples,and Vi
9、nyl Chloride Content of Poly(Vinyl Chloride) Resin, Slurry, Wet Cake, and Latex Samples429 CFR 1919.1017 Vinyl Chloride for Regulated Levels of Exposure52.3 ISO Standard:ISO 6401 Determination of Residual Vinyl Chloride Monomer in Homopolymers and Copolymers by Gas Chromatography61 This test method
10、is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Oct. 1, 2012Nov. 1, 2013. Published November 2012November 2013. Originally approved in 1978. Last previous edition approved in 20082012as
11、 D3749 - 08.D3749 - 12. DOI: 10.1520/D3749-12.10.1520/D3749-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM websit
12、e.3 The last approved version of this historical standard is referenced on www.astm.org.4 Available from United States Environmental Protection Agency (EPA), Ariel Rios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460, http:/www.epa.gov.5 Available from U.S. Government Printing Office Superin
13、tendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.6 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to
14、provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof
15、the standard as published by ASTM is to be considered the official document.*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. Terminology3.1 Acronyms:3.1.1 VCMVinyl chl
16、oride 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 detector.3.1.8 MHEMultiple headspace extraction.4. Summary of T
17、est Method4.1 The basis for this test method relates to the vapor equilibrium that is established between RVCM, PVC resin, and air in aclosed system. The RVCM in a PVC resin will equilibrate in a closed vessel quite rapidly, provided that the temperature of thePVC resin is maintained above the glass
18、 transition temperature of that specific resin type.4.2 After sample equilibration, conventional gas chromatographic (GC) techniques are used. A constant amount of sampleheadspace vapor is injected into a GC column that is packed with a liquid-coated solid support or porous polymer beads. Sampleinje
19、ction is accomplished by available commercial automatic equipment. Passing through the column in a stream of carrier gas,the vinyl chloride monomer (VCM) is separated from other components which may be present and is detected by a standardsensing device. The signal is recorded to indicate the relati
20、ve concentration of the VCM and its retention time.4.3 Refer to Practice D4526 for additional information on headspace gas chromatography.5. Significance and Use5.1 Poly(vinyl chloride) resins must contain a minimum possible amount of unreacted, or free, VCM.5.2 This test method provides a measure o
21、f RVCM which is suitable for manufacturing control or specification acceptancepurposes.5.3 Under optimum conditions, a lower level of detection of 2 ppm by volume VCM can be detected in the headspace vapor.Using a 4-g sample, this is equivalent to about 0.02 ppm by mass RVCM in the PVC resin.6. Inte
22、rferences6.1 Normally, the vapor above PVC resin will contain only air, VCM, water, small amounts of catalyst breakdown products,and any solvents or comonomers used in polymerization. Impurities in the 0 to 1000-ppm range will generally have only a verysmall influence on this equilibrium relationshi
23、p.6.2 Any material that elutes from the chromatographic column at approximately the same time as vinyl chloride will cause highRVCM results.7. Apparatus7.1 Gas Chromatograph, equipped with a flame ionization detector (FID), photoionization detector (PID), or a Hallelectroconductivity detector (HED)
24、and capable of heating, sampling, and analyzing the headspace vapors contained in sealedvials.NOTE 2Automatic backflushing capability may be a desirable option for some copolymer samples to reduce the time of analysis.7.2 Chromatographic Column, 80/100-mesh in 1-m by 3.2-mm stainless steel tubing.NO
25、TE 3Any column that will resolve VCM from any interferences and will elute VCM between 1 and 4 min using a system pressure of 100 to 150kPa is satisfactory. If an alternate column is used, the chromatographic conditions may need to be modified.7.3 Integrator, or computerized data system for peak mea
26、surements.7.3 Balance, capable of weighing to 61 % of sample weight.7.4 Accessories, for headspace samples, including vials, septa, seals, and crimper.7.5 Syringe, 100-L capacity, 24-gage needle.7.7 Programmable Calculator, or computer.D3749 1328. Reagents and Materials8.1 StandardsCylinders of know
27、n concentrations of vinyl chloride in nitrogen gas. Nominal concentrations of 5, 50, and 500ppm by volume (vppm) are needed, unless multiple headspace extraction (MHE) is used. Lower concentration standards shall beused for detection limits less than 2 ppm.8.2 Nitrogen, or helium, oxygen-free, carri
28、er gas for chromatograph.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 and must never be released to the laboratory atmosphere, even at low ppmlevels.Venting or purging ofVCM mixtures must be held
29、to a minimum and shall be vented into a properly functioning fume hood.Refer to 29 CFR 1919.1017 for regulated levels of exposure.9.2 Be careful not to come into contact with heated parts of the chromatograph, such as the detector, column, hot vials, etc.Handle all electrical connections with care.9
30、.3 Vials shall be vented to atmospheric pressure after analysis and prior to removal from the thermostatted turntable. Ahypodermic needle connected to a syringe containing a freshly activated charcoal is suitable for this operation.10. Sampling and Storage10.1 Weigh and seal resin samples in the hea
31、dspace vials in accordance with 12.1 as soon as possible, not to exceed 24 h.10.2 It is possible to store resins in the sealed headspace vials for up to four weeks without loss of VCM if they are analyzedwithout being reopened.11. Preparation of Gas Chromatograph11.1 Connect carrier gas and detector
32、 gas cylinders to the chromatograph with the recommended filters and regulators asrequired by the manufacturer.11.2 Establish correct control of the thermostatted headspace unit.11.3 Install the chromatographic column connected to the injector only. Establish an appropriate flow rate, and condition
33、thecolumn overnight at 150C. After conditioning, cool and connect the column exit to the detector.NOTE 4See Appendix XI for recommendations for particular instrument parameters.11.4 Set the pressure and flow of hydrogen and air to the detector in accordance with the manufacturers recommendations.Ign
34、ite the flame.11.5 Set other chromatograph controls as necessary to obtain the desired resolution and sensitivity for the instrument used, asfollows:11.5.1 Analysis time (and backflush time, if used) as required, depending on the location time of VCM.11.5.2 Detector, recorder, and integrator sensiti
35、vities as needed to detect the VCM levels in the samples. Ensure that the systemis capable of producing a measurement for a 50-ppm vinyl chloride standard that is at least 10 times the standard deviation of thesystem background noise level.11.6 Establish the proper combination of oven temperature an
36、d carrier flow rate to obtain a resolved, symmetrical VCM peakeluting from the chromatographic column between 60 and 250 s after injection. Record the system head pressure under thoseconditions.12. Calibration12.1 Prepare calibration standards by filling vials with the VCM in nitrogen standards, rap
37、idly seating the septum, sealing withthe aluminum retainer, and injecting 100 L of distilled water.12.1.1 Purge the sample line from the cylinder into the hood prior 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,
38、 place the end of the tubing into a vial to the bottom. Position the septum ontop of the vial, pressing it against the tube to minimize mixing air with the standard gas in the vial. Purge each vial with the standardfor at least 60 s.12.1.3 Gradually slide the tube to the top of the vial, simultaneou
39、sly sealing the vial with the septum as the tube is withdrawn.12.1.4 Crimp an aluminum retainer over the septum.12.1.5 Inject 100 L of organic-free water into the vial with a burr-free, 24-gage needle to ensure uniformity of water vaporcontribution to the vial pressure.D3749 13312.2 For each series
40、of samples to be tested, prepare two vials each of the three standard gases. These calibration standards willbe analyzed along with the samples in exactly the same manner and at the same detector range.13. Procedure13.1 Sample PreparationAdd 0.2 to 4 g 6 10 % of resin to a tared vial. Record exact w
41、eight to 61 %.Add by pipet, 2 dropsof organic-free water, and immediately seal the vial.13.2 Place the vials in the analyzer turntable in the order required 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 he
42、adspace in each equilibrated vial to determine the VCM peak area.13.5 Depressurize each vial with a needle after analysis prior to removal from the turntable. (See 9.3.)14. Calculation14.1 Calculate the individual response factors for the standards as follows:Rfi 5Ai!/Ci! (1)where:Rfi = response fac
43、tor from standard in Vial i,Ai = VCM peak area from Vial i, counts, andCi = concentration of VCM, ppm by volume, in standard gas in Vial i.14.2 Calculate the average response factor for the six standards. (Compare the factors to each other and previously determinedfactors. Investigate any large diff
44、erences.)14.3 The generalized headspace equation for the VCM/PVC resin system is as follows:Cvcm 5As PaRf T1FMv VgmR 1Kp T2 G (2)where:Cvcm = concentration of residual vinyl chloride in resin, ppm by weight,As = VCM peak area in sample, counts,Pa = atmospheric pressure, mm Hg,Rf = average response f
45、actor, 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 vial5m!/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 PVC
46、 homopolymer at 90C), andT2 = equilibration temperature (363 K).NOTE 5This equation is best solved using a programmable calculator or computer.14.4 The generalized equation can be simplified for a particular set of conditions, assuming the following conditions are met:14.4.1 A sample is a PVC homopo
47、lymer containing less than 1 % water (Kp = 6.52 106).14.4.2 Vials have a total capacity of 23 6 1 cm3 (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 Equilibration temperature is 90 6 1C (T2 = 363).14.5 The equation in 14.3
48、under the conditions in 14.4.1 through 14.4.5 reduces toCvcm 52.54 AsRf0.0205m 10.0024 (4)15. Report15.1 Report the calculated residual vinyl chloride concentrations to two significant figures in parts per million by weight(mg/kg) of dry resin.D3749 13416. Precision and Bias716.1 PrecisionValues wer
49、e determined in accordance with Practice E691 using data from an interlaboratory evaluation ofthree materials analyzed in duplicate (same day) by six laboratories:Average RVCM (g/g)400 12 to 18Withinlaboratory (Sr)21.5 0.62Betweenlaboratories(SR )53.3 0.9116.1.1 Another sample containing an average RVCM level of 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 or alternative test method, there is no estimate of bias.17. Keywords17.1 gas chroma
