1、Designation: D4766 98 (Reapproved 2014)Standard Test Method forVinyl Chloride in Workplace Atmospheres (Charcoal TubeMethod)1This standard is issued under the fixed designation D4766; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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. Scope1.1 This test method describes the determination of vinylchloride monomer (VCM) in workplace atmospheres usin
3、g amodified charcoal tube method (see Practice D3686).1.2 This procedure is compatible with low flow rate per-sonal sampling equipment. It can be used for personal orstationary monitoring. It cannot determine instantaneous fluc-tuations in concentration to detect maximum values. Alterna-tive on-site
4、 procedures, such as gas chromatography or infraredspectrometry, must be used to measure fast-changing concen-trations.1.3 The range of this test method is from the limit ofdetection of approximately 0.01 to 100 ppm (v).1.4 The sampling method provides a time-weighted averagesample.1.5 The values st
5、ated in SI units are to be regarded asstandard. The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its
6、 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. For more specificprecautionary statements, see Section 9 and Warnings in 10.2.3and 11.1.3.2. Referenced Documents2
7、.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD3686 Practice for Sampling Atmospheres to Collect Or-ganic Compound Vapors (Activated Charcoal Tube Ad-sorption Method)E355 Practice for Gas Chromatography Terms and Relation-ships3. Terminology3.1 DefinitionsFor de
8、finitions of terms relating to this testmethod, refer to Terminology D1356 and Practice E355.4. Summary of Test Method4.1 Known volumes of sample air are passed through glassor metal tubes packed with activated charcoal. Vinyl chloride isadsorbed on the charcoal and thus removed from the flowinggas
9、stream (1-3).34.2 A two-section tube containing a front and a backupsection of adsorbent is used to collect the sample.4.3 The vinyl chloride is desorbed with carbon disulfide andanalyzed with a gas chromatograph equipped with a flameionization detector. Two or more different columns are to beused t
10、o reveal interferences that might otherwise not bedetected.4.4 Adsorption/desorption efficiencies are determined bythe same techniques used for the atmospheric analysis appliedto known standards. Instrument calibrations are made withprepared standard solutions of vinyl chloride in carbon disul-fide.
11、5. Significance and Use5.1 Vinyl chloride monomer (VCM) is the starting materialfor the manufacture of poly(vinyl chloride) (PVC), which isused extensively in construction, electronics, packaging, andother industries. The vinyl chloride gas can escape duringmanufacturing, transportation, and polymer
12、ization stages. Re-sidual monomer can also escape during subsequent fabricationprocesses.5.2 Vinyl chloride is a toxic and explosive hazardousmaterial.1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.04 on Workplace
13、AirQuality.Current edition approved Sept. 1, 2014. Published September 2014. Originallyapproved in 1988. Last previous edition approved in 2009 as D4766 98 (2009)1.DOI: 10.1520/D4766-98R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
14、eastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to the list of references at the end ofthis test method.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Co
15、nshohocken, PA 19428-2959. United States15.3 Vinyl chloride is suspected to be a carcinogenic agent(4), and occupational exposure limits (OELs) have beenestablished for this agent. For instance, the present U.S.Occupational Safety and Health Administration (OSHA) stan-dard for VCM is 1.0 ppm (v) wit
16、h a 0.5-ppm (v) action level;the maximum length of operator exposure at 5 ppm (v) is 15min.45.4 The method is made selective for vinyl chloride bychoosing chromatograph columns that will separate vinylchloride from other organic compounds in the sample.5.5 The method meets requirements (for example,
17、 those ofOSHA) for monitoring workplace atmospheres in vinyl chlo-ride and poly(vinyl chloride) production and fabrication pro-cesses.6. Interferences6.1 Organic components that have the same or nearly thesame retention time as vinyl chloride during gas-chromatographic analysis will interfere.6.2 Ot
18、her volatile organic compounds in the area samplesshould be given consideration.6.3 Such interferences can be minimized by proper selectionof gas-chromatographic columns. A mass spectrometric detec-tor can be used to confirm the presence of vinyl chloride.6.4 Water mists and high humidity affect ads
19、orption effi-ciencies by reducing the adsorptive capacity of the charcoal forvinyl chloride.7. Apparatus7.1 Charcoal Sampling Tube:7.1.1 DescriptionA sampling tube consists of a length ofglass tubing containing two sections of activated charcoal thatare held in place by nonadsorbent material and sea
20、led at eachend.7.1.2 Sampling tubes are commercially available and con-sist of a glass tube 110 mm long, 10 mm in outside diameter,and 8 mm in inside diameter. They contain two sections of20/40 mesh activated charcoal, 800 and 200 mg, each separatedby a 2-mm section of urethane foam. The front secti
21、on isretained by a plug of glass wool and the back section is retainedby a second 2-mm portion of urethane foam or other retainer,such as glass wool. The ends of the tube are flame sealed.7.1.3 The back section of the sample tube (200 mg) adsorbsvapors that penetrate the front section and is used to
22、 determinewhether the collection capacity of the tube has been exceeded.Instead of a single tube, two tubes in series may be used (see11.1.11).7.1.4 The pressure drop across the charcoal tube should beno greater than 2.5 cm Hg 3.3 kPa at a flowrate of 1000mL/min.7.1.5 Glass tubes must be held in sui
23、table protective holdersto prevent breakage during sampling.7.2 Syringes:7.2.1 Gas-Tight Syringe, 1 to 2-mL capacity.7.2.2 Microlitre Syringes, 10, 25, and 100-L or otherconvenient sizes for making standards.7.3 Polyethylene End Caps, for capping charcoal tube. Capsmust fit snugly to prevent leakage
24、.7.4 Vials, glass, approximately 12 mL (3-dram), for desorb-ing samples and holding standards, polyethylene or TFE-fluorocarbon-lined screw cap or septum valve.A1-oz vial withthe same types of closure is needed for standard preparation.7.5 Plastic BagsPoly(vinylidine chloride) or poly(vinylfluoride)
25、, 50 to 100 L, for preparing known concentrations ofvinyl chloride. The significant solubility of vinyl chloride inpolytetrafluorethylene renders bags made of this type of filmunsuitable. Other equivalent containers for preparing knownconcentrations are also suitable.7.6 Sampling EquipmentSee Ref (5
26、) for general informa-tion on air sampling instrumentation.7.6.1 Any pump whose flow rate can be accurately deter-mined and set at the desired sampling rate is suitable.7.6.2 Pumps having stable low flow rates (10 to 200mL/min) are preferable for long period sampling (up to 8 h) orfor short periods
27、when concentration of organic vapors areexpected to be high.7.6.3 All sampling pumps must be carefully calibrated witha charcoal tube in the proper sampling position. (See PracticeD3686 and Annex A1.)7.6.4 Tubing, rubber or plastic, 6-mm 14 in., bore about0.9 m 3 ft long, equipped with a spring clip
28、 to hold the tubingand charcoal tube in place on workers lapel area (Note 1).NOTE 1Sampling tubes must not be used with plastic or rubber tubingupstream of the charcoal. Absorption by the tubing may introducesampling errors.7.7 Gas Chromatograph:7.7.1 Gas chromatographs that employ either a flame io
29、n-ization detector or a detector whose specifications are equiva-lent in sensitivity and selectivity should be used. Detectorsmust be capable of determining vinyl chloride concentrationsof interest with a signal-to-noise ratio of at least 10 to 1.Suitable detectors are capable of detecting approxima
30、tely51010g of vinyl chloride per injection.7.7.2 A gas-chromatographic column capable of separatingvinyl chloride from other components is required.Anumber ofsuitable columns have been discussed in the literature (6).Table 1 lists 14 columns and the oven temperatures used forvinyl chloride determina
31、tion. Table 2 lists the relative retentiontimes of some potential interferences for four chromatographiccolumns. Column suitability must be verified by testing withtwo or more columns of dissimilar packings to ensure theabsence of interferences. If the chromatographic peak for vinylchloride overlaps
32、 the peak for other components by no greaterthan 5 %, the separation is considered to be satisfactory.7.7.3 Gas chromatographic operating conditions for theinstrument being used should be optimized so that the separa-tion required for a successful analysis can be obtained in areasonable time.4Federa
33、l Register, 39, 194 (1974).D4766 98 (2014)28. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise noted, all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are
34、 available.5Other reagents may be usedprovided it can be demonstrated that they are of sufficientlyhigh purity to permit their use without decreasing the accuracyof determination.8.2 Activated Coconut-Shell CharcoalCommerciallyavailable coconut charcoal (20/40 mesh) has been found tohave adequate ad
35、sorption capacity.8.3 Calibration StandardsStandard concentrations of vi-nyl chloride in air may be purchased or prepared in thelaboratory. Laboratory standard concentrations are prepared bypressure dilution in stainless steel cylinders, atmosphericpressure dilution in plastic bags, or dynamically w
36、ith perme-ation tubes (22). These standards are used to determineadsorption/desorption efficiencies of the activated charcoal(Annex A1).8.4 Carbon Disulfide (CS2), spectroquality.8.5 Vinyl Chloride (VCM), gas cylinder.9. Safety Precautions9.1 Carbon disulfide and vinyl chloride vapors are toxic andh
37、ighly flammable. Usage should be restricted to a well-ventilated hood.9.2 Small waste quantities of carbon disulfide shall bedisposed of only in accordance with local regulations andaccepted practices.9.3 The vapors of vinyl chloride should not be inhaled sincethey have anesthetic properties and are
38、 suspected to becarcinogenic.9.4 Avoid skin contact with carbon disulfide, solutions ofvinyl chloride in CS2, and vinyl chloride liquid.10. Calibration and Standardization10.1 Sample Pump CalibrationCalibrate the sample pumpflow in accordance with Practice D3686 and Annex A1.10.2 Standardization:10.
39、2.1 Prepare calibration standards as micrograms of vinylchloride per 10 mL of carbon disulfide over range of interest.10.2.2 Pipet 30 mLof carbon disulfide into a 1-oz bottle andseal.10.2.3 Fill a 1.0-mL gas-tight syringe with pure vinylchloride vapor from a cylinder of pure vinyl chloride.(WarningH
40、andle the pure vinyl chloride gas in a hood.)10.2.4 Inject 1.0 mL of vinyl chloride vapor (through theseptum) directly into the carbon disulfide in the vial. Mixthoroughly. This standard contains 852 g of vinyl chloride per10 mL of carbon disulfide and is equivalent to 13.3 ppm in airbased on a 25-L
41、 sample. Prepare in duplicate (Note 2).NOTE 2The concentration of the standard solution is based on5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on testing of reagents not listedby theAmerican Chemical Society, see Analar Stan
42、dards for Laboratory Chemicals,BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.TABLE 1 Common Packings and Oven Temperatures for theVinyl Chloride AnalysisColumn PackingOven Temperature,CReference10 to
43、 20 ft 3 to 6 m SE-30 onChromosorb G, Chromosorb W. orAnakrom ABSambient to 90 3, 7, 820 ft 6 m 10 % FFAP on ChromosorbW65 36 ft 1.8 m Poropak Q 100135 2, 9, 105 to 6 ft 1.5 to 1.8 m Poropak QS 70120 1, 11, 126 ft 1.8 m Chromosorb 101 90100 13, 141.5 to 6 ft 0.5 to 1.8 m Chromosorb102A70145 15, 16,
44、17, 186 ft 1.8 m 1020 % DC 200 onChromosorb W or Supelcoport80 1, 1620 ft 6 m Carbowax 4000 onSupelcoport80 16 ft 1.8 m 0.4 % Carbowax 1500 onCarbopak Aambient 16, 196 ft 1.8 m 5 % OV-101 onChromosorb Wambient 106 ft 1.8 m 10 % Apiezon M onChromosorb Wambient 106 ft 1.8 m silica gel 30 20300 ft 90 m
45、 open tubular column,coated with dibutyl maleate0 2016 ft 4.8 m 16.7 % triscyanoethoxypropane on Chromosorb Wprogrammedfrom50to17021TABLE 2 Relative Retention Times of Potential Interferences toVinyl Chloride(Vinyl Chloride Retention = 1.0)CompoundChromo-sorbA102Chromo-sorbB102Poro-pak QC0.4 %Carbow
46、axD1500 onCarbopak AMethane 0.15 . 0.05 0.20Ethane 0.21 . . 0.29Ethene 0.21 0.33 . 0.261,1-Difluoroethylene . 0.33 . 0.63Propene . 0.62 0.46 0.63Propane 0.54 . 0.52 0.63Methylacetylene . . 0.56 .Methyl chloride 0.63 . 0.57 0.451,1-Difluoroethane . 0.51 . .Chlorodifluoromethane . 0.53 . .Cyclopropane
47、 . . 0.59 .Formaldehyde . . 0.62 .1-Chloro-1,1-difluoro-ethane. 0.92 . .Acetyladehyde 0.93 . 0.95 0.77Dichlorotetrafluoroethane . 1.21 . .Isobutane 1.22 . . .Isobutylene 1.37 1.25 . .Methanol . . . 1.381,3-Butadiene 1.57 1.27 . .1-Butene 1.43 1.30 . .Vinyl methyl ether . 1.36 . .Trans-2-butene 1.57
48、1.38 . 2.92Ethyl chloride 1.70 . . 1.54Cis-2-butene 1.73 1.43 . .Vinyl bromide . 1.85 . .1,1-dichloroethylene 2.00 . . .A6ftby18 in. Chromosorb 102 (80/100 mesh) at 100C.B6ftby18 in. Chromosorb 102 (80/100 mesh) at 145C.C6ftby18 in. Poropak Q (80/100 mesh) at 100C.D6ftby18 in. 0.4 % Carbowax 1500 on
49、 Carbopak A at ambient temperature.D4766 98 (2014)3injection of 1.0 mLof gas at 25C and 1 atmosphere (101.3 kPa). For otherconditions of temperature and pressure, the concentration should bemultiplied by a correction factor, as follows:Correction Factor 5barometric pressure kPa!101.3 kPa3298C1273(1)10.2.5 Prepare a dilute standard by pipetting 1 mL of theabove standard solution into a 3-dram vial containing 10 mLofcarbon disulfide giving a total volume of 11 mL. Cap imme-diately with a septum valve. This standard
