1、Designation: D 4766 98 (Reapproved 2003)Standard Test Method forVinyl Chloride in Workplace Atmospheres (Charcoal TubeMethod)1This standard is issued under the fixed designation D 4766; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 describes the determination of vinylchloride monomer (VCM) in workplace atmospheres u
3、sing amodified charcoal tube method (see Practice D 3686).1.2 This procedure is compatible with low flow rate per-sonal sampling equipment. It can be used for personnel orstationary monitoring. It cannot determine instantaneous fluc-tuations in concentration to detect maximum values. Alterna-tive on
4、-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 provides a time-weighted averagesample.1.5 This sta
5、ndard 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 health practices and determine the applica-bility of regulatory limitations prior to use. For more specificprecautio
6、nary statements, see Section 9 and Notes 2 and 4.2. Referenced Documents2.1 ASTM Standards:2D 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 3686 Practice for Sampling Atmospheres to Collect Or-ganic Compound Vapors (Activated Charcoal Tube Ad-sorption Method)E 355 Practice for Ga
7、s Chromatography Terms and Rela-tionships3. Terminology3.1 DefinitionsFor definitions of terms relating to this testmethod, refer to Terminology D 1356 and Practice E 355.4. Summary of Test Method4.1 Known volumes of sample air are passed through glassor metal tubes packed with activated charcoal. V
8、inyl chloride isadsorbed on the charcoal and thus removed from the flowinggas 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
9、with a flameionization detector. Two or more different columns are to beused to 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 ar
10、e made withprepared standard solutions of vinyl chloride in carbon disul-fide.5. Significance and Use5.1 Vinyl chloride monomer is the starting material for themanufacture of poly(vinyl chloride) (PVC), which is usedextensively in construction, electronics, packaging, and otherindustries. The vinyl
11、chloride gas can escape during manufac-turing, transportation, and polymerization stages. Residualmonomer can also escape during subsequent fabrication pro-cesses.5.2 Vinyl chloride is a toxic and explosive hazardousmaterial.5.3 Vinyl chloride is suspected to be a carcinogenic agent(4). The present
12、OSHA standard for VCM is 1.0 ppm (v) witha 0.5-ppm (v) action level. The maximum length of operatorexposure at 5 ppm (v) is 15 min.41This test method is under the jurisdiction of ASTM Committee D22 onSampling and Analysis of Atmospheres and is the direct responsibility of Subcom-mittee D22.04 on Wor
13、kplace Atmospheres.Current edition approved April 10, 2003. Published June 2003. Originallyapproved in 1988. Last previous edition approved in 1998 as D 4766 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book o
14、f 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.4Federal Register, 39, 194 (1974).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
15、West Conshohocken, PA 19428-2959, United States.5.4 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 the federal requirements for moni-toring workplace atmospheres in viny
16、l chloride and poly(vinylchloride) production and fabrication processes.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 samplesshould be gi
17、ven 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 adsorptive capacity of t
18、he 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 commercially available
19、 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 the back section is
20、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 the tube has been
21、 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 during sampling.7.
22、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, 3-dram approximately 12 mL, for desorb-ing
23、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 concentrations ofvinyl chlor
24、ide. 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 instrumentation.7.6.
25、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 areexpected to be high.7.6
26、.3 All sampling pumps must be carefully calibrated witha charcoal tube in the proper sampling position. (See PracticeD 3686 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 place on workers lapel
27、 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 specifications are equi
28、va-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 injection.7.7.2 A gas-chro
29、matographic 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 retentiontimes of some pot
30、ential interferences for four chromatographicTABLE 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, 920 ft 6 m 10 % FFAP on ChromosorbW65 36 ft 1.8
31、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 4000 onSupelcoport80 16 ft 1.8 m 0.4 % Carbow
32、ax 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 % triscyanoethoxypropane on Chromosorb Wprogrammedfrom50to17022
33、D 4766 98 (2003)2columns. Column suitability must be verified by testing withtwo or more columns of dissimilar packings to assure theabsence of interferences. If the chromatographic peak for vinylchloride overlaps the peak for other components by no greaterthan 5 %, the separation is considered to b
34、e 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 chemicals shall beused in all tests. Unless oth
35、erwise noted, all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.5Other reagents may be usedprovided it can be demonstrated that they are of sufficientlyhigh purity to permit their use withou
36、t 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 StandardsStandard concentrations of vi-nyl chloride in air may be purchased or prepared in thelaborator
37、y. Laboratory standard concentrations are prepared bypressure dilution in stainless steel cylinders, atmosphericpressure dilution in plastic bags, or dynamically with perme-ation tubes (7). These standards are used to determineadsorption/desorption efficiencies of the activated charcoal(Annex A1).8.
38、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 restricted to a well-ventilated hood.9.2 Small waste quantities of carbon disulfide shall bedisposed of o
39、nly 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 skin contact with carbon disulfide, solutions ofvinyl chloride in CS2, and vinyl chloride liquid.10
40、. Calibration and Standardization10.1 Sample Pump CalibrationCalibrate the samplepump flow in accordance with Practice D 3686 and Annex A1.10.2 Standardization:10.2.1 Prepare calibration standards as micrograms of vinylchloride per 10 mL of carbon disulfide over range of interest.10.2.2 Pipet 30 mLo
41、f carbon disulfide into a 1-oz bottle andseal with a Mininert valve.10.2.3 Fill a 1.0-mL gas-tight syringe with pure vinylchloride vapor from a cylinder of pure vinyl chloride.NOTE 2Warning: Handle the pure vinyl chloride gas in a hood.10.2.4 Inject 1.0 mL of vinyl chloride vapor (through theseptum)
42、 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 3).NOTE 3The concentration of the standard solution is based oninjection
43、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 kPa3298C 1 273(1)10.2.5 Prepare a dilute standard by pipetting 1 mL of theab
44、ove 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 disulfide and is equivalent to 1.18 ppm in airbased on a 25-L sample.10.2.6 Additional standards are prepared
45、 by dilution of theabove standards with carbon disulfide. Care must be taken inthe dilution steps to minimize the chance of vinyl chloride loss.10.2.7 Analyze each vinyl chloride in carbon disulfidestandard in duplicate by gas chromatography.5Reagent Chemicals, American Chemical Society Specificatio
46、ns, 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 Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (
47、USPC), Rockville, MD.TABLE 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 . 0.261,1-Difluoroethylene . 0
48、.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 0.93 . 0.95 0.77Dichlorot
49、etrafluoroethane . 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 . .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 temperatu
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