1、Designation: D4766 98 (Reapproved 2009)1Standard 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.1NOTEReapproved with editorial changes in October 2009.1. Scope1.1 This test method describes the determination of v
3、inylchloride monomer (VCM) in workplace atmospheres using 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 conc
4、entration to detect maximum values. Alterna-tive on-site 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
5、provides a time-weighted averagesample.1.5 The values stated in SI units shall be regarded as thestandard. Inch-pound units are provided for information only.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
6、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 Documents2.1 ASTM Standards:2D1356 Terminology Relat
7、ing 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 Rela-tionships3. Terminology3.1 DefinitionsFor definitions of terms relating to this testme
8、thod, 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 stream (1-3).34.2 A two-section tube conta
9、ining 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 to reveal interferences that might otherwis
10、e 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.5. Significance and Use5.1 Vinyl chloride
11、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 polymerization stages. Re-sidual monomer can also
12、 escape during subsequent fabricationprocesses.5.2 Vinyl chloride is a toxic and explosive hazardousmaterial.5.3 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.1This test method is
13、under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.04 on Workplace AirQuality.Current edition approved Oct. 1, 2009. Published December 2009. Originallyapproved in 1988. Last previous edition approved in 2003 as D4766 98(03). DOI:10.1520/D
14、4766-98R09E01.2For 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.3The boldface numbers in parentheses refer to t
15、he list of references at the end ofthis test method.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Occupational Safety and Health Administration (OSHA) stan-dard for VCM is 1.0 ppm (v) with a 0.5-ppm (v) action level;the maximum len
16、gth 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, those ofOSHA) for monitoring workplace atmo
17、spheres 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 Other volatile organic compounds in the area s
18、amplesshould 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 adsorption effi-ciencies by reducing the adsorp
19、tive 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 sealed at eachend.7.1.2 Sampling tubes are comm
20、ercially 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 section isretained by a plug of glass wool and th
21、e 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 determinewhether the collection capacity of
22、 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 suitable protective holdersto prevent breakage
23、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.7.4 Vials, glass, approximately 12 mL (3-dr
24、am), 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), 50 to 100 L, for preparing known concentr
25、ations 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) for general informa-tion on air sampling
26、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 when concentration of organic vapors areexp
27、ected 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 to hold the tubingand charcoal tube in pla
28、ce 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 ion-ization detector or a detector whose spec
29、ifications 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 approximately5 3 1010g of vinyl chloride per injecti
30、on.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 determination. Table 2 lists the relative retenti
31、ontimes 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 the peak for other components by no gre
32、aterthan 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.8. Reagents8.1 Purity of ReagentsReagent grade
33、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 such4Federal Register, 39, 194 (1974).D4766 98 (2009)12specifications are available.5Other reagents may be usedp
34、rovided 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 adsorption capacity.8.3 Calibration Stand
35、ardsStandard 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 with perme-ation tubes (7). These standa
36、rds 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 andhighly flammable. Usage should be restric
37、ted 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 suspected to becarcinogenic.9.4 Avoid s
38、kin contact with carbon disulfide, solutions ofvinyl chloride in CS2, and vinyl chloride liquid.10. Calibration and Standardization10.1 Sample Pump CalibrationCalibrate the samplepump flow in accordance with Practice D3686 and Annex A1.10.2 Standardization:10.2.1 Prepare calibration standards as mic
39、rograms 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.(WarningHandle the pure vinyl chloride gas in a h
40、ood.)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 sample. Prepare in duplicate (Note 2).N
41、OTE 2The concentration of the standard solution is based oninjection 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 kPa3298
42、C 1 273(1)5Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on testing of reagents not listedby theAmerican Chemical Society, see Analar Standards for Laboratory Chemicals,BDH Ltd., Poole, Dorset, U.K., and the United States Phar
43、macopeia 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 20 ft 3 to 6 m SE-30 onChromosorb G, Chromosorb W. orAnakrom ABSambient to 90 3, 8, 92
44、0 ft 6 m 10 % FFAP on ChromosorbW65 36 ft 1.8 m Poropak Q 100135 2, 10, 115 to 6 ft 1.5 to 1.8 m Poropak QS 70120 1, 12, 136 ft 1.8 m Chromosorb 101 90100 14, 151.5 to 6 ft 0.5 to 1.8 m Chromosorb102A70145 16, 17, 18, 196 ft 1.8 m 1020 % DC 200 onChromosorb W or Supelcoport80 1, 1720 ft 6 m Carbowax
45、 4000 onSupelcoport80 16 ft 1.8 m 0.4 % Carbowax 1500 onCarbopak Aambient 17, 206 ft 1.8 m 5 % OV-101 onChromosorb Wambient 116 ft 1.8 m 10 % Apiezon M onChromosorb Wambient 116 ft 1.8 m silica gel 30 21300 ft 90 m open tubular column,coated with dibutyl maleate0 2116 ft 4.8 m 16.7 % triscyanoethoxy
46、propane on Chromosorb Wprogrammedfrom50to17022TABLE 2 Relative Retention Times of Potential Interferences toVinyl Chloride(Vinyl Chloride Retention = 1.0)CompoundChromo-sorbA102Chromo-sorbB102Poro-pak QC0.4 %CarbowaxD1500 onCarbopak AMethane 0.15 . 0.05 0.20Ethane 0.21 . . 0.29Ethene 0.21 0.33 . 0.2
47、61,1-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 . . 0.59 .Formaldehyde . . 0.62 .1-Chloro-1,1-difluoro-ethane. 0.92 . .Acetyladehyde
48、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 1.38 . 2.92Ethyl chloride 1.70 . . 1.54Cis-2-butene 1.73 1.43 . .Vinyl bromide . 1.85
49、. .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 Carbopak A at ambient temperature.D4766 98 (2009)1310.2.5 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 contains 77.5 g/10mL of carbon
