1、Designation: D3687 07 (Reapproved 2012)Standard Practice forAnalysis of Organic Compound Vapors Collected by theActivated Charcoal Tube Adsorption Method1This standard is issued under the fixed designation D3687; the number immediately following the designation indicates the year oforiginal adoption
2、 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. Scope1.1 This practice covers the applications of methods for theextraction and gas c
3、hromatographic determination of organicvapors that have been adsorbed from air in sampling tubespacked with activated charcoal.1.2 This practice is complementary to Practice D3686.1.3 This practice is applicable for analysis of samples takenfrom workplace or other atmospheres provided that the con-t
4、aminant adsorbs onto charcoal, that it can be adequatelyextracted from the charcoal, and that it can be analyzed by gaschromatography (GC). Other adsorbents and other extractiontechniques are described in Practice D6196.1.4 Organic compounds of multicomponent samples maymutually interfere during ana
5、lysis. Methods to resolve inter-ferences are given in Section 6.1.5 The values stated in 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 establ
6、ish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tions are given in 8.4, 9.2, and in A1.2.3.2. Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD3686 Practice
7、for Sampling Atmospheres to Collect Or-ganic Compound Vapors (Activated Charcoal Tube Ad-sorption Method)D6196 Practice for Selection of Sorbents, Sampling, andThermal Desorption Analysis Procedures for Volatile Or-ganic Compounds in AirE355 Practice for Gas Chromatography Terms and Rela-tionships2.
8、2 NIOSH Standards:CDC-99-74-45 Documentation of NIOSH ValidationTests3NIOSH Manual of Analytical Methods, 4thEd.42.3 OSHA Standards:29 CFR 1910 Code of Federal Regulations, RegulationsRelating to Labor, Occupational Safety and Health Ad-ministration, Department of Labor5OSHA Sampling and Analytical
9、Methods62.4 UK Health and Safety Executive (HSE):7Methods for the Determination of Hazardous Substances(MDHS)2.5 Berufsgenossenschaftliches Institut fr Arbeitsschulz(BGIA):8GESTIS Analytical Methods3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, refer tothe termin
10、ology specified in D1356 and E355.4. Summary of Practice4.1 Organic vapors that have been collected on activatedcharcoal are extracted with carbon disulfide or another appro-priate solvent and are determined by GC using a flameionization detector (FID). Carbon disulfide is a relatively smallmolecule
11、 that can penetrate the “ink-bottle” shaped pores ofactivated charcoal, it has a high heat of adsorption on activatedcharcoal which helps in displacing other adsorbed molecules,and it is a reasonably good solvent for most, especially1This practice is under the jurisdiction of ASTM Committee D22 on A
12、ir Qualityand is the direct responsibility of Subcommittees D22.04 on Workplace Air Quality.Current edition approved April 1, 2012. Published July 2012. Originallyapproved in 1978. Last previous edition approved in 2007 as D3687 - 07. DOI:10.1520/D3687-07R12.2For referenced ASTM standards, visit the
13、 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.3Available from the U.S. Department of Commerce, National Technical Infor-mation Service, Port Royal R
14、oad, Springfield, VA 22161.4NIOSH Manual of Analytical Methods (NMAM). http:/www.cdc.gov/niosh/nmam/ (accessed 1/2007).5Available from Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.6OSHA Sampling and Analytical Methods, http:/www.osha.gov/dts/sltc/methods/index.ht
15、ml (accessed 1/2007).7HSE Methods for the Determination of Hazardous Substances (MDHS).http:/www.hse.gov.uk/pubns/mdhs/index.htm# (accessed 1/2007).8GESTIS Analytical Methods. http:/www.hvbg.de/e/bia/gestis/analytical_methods/index.html (accessed 1/2007).1Copyright ASTM International, 100 Barr Harbo
16、r Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.non-polar, organic molecules. Polar modifiers (such as N,N-dimethylformamide) are frequently added to enhance the re-covery of polar organic compounds. Other advantages to usingcarbon disulfide include an early elution time on mos
17、t GCcolumns and a small FID response.4.2 Interferences resulting from the analytes having similarretention times during GC analysis are resolved by changingthe GC column, by changing the operating parameters, or byfractionating the sample using solvent extraction as describedin Section A1.1.4.3 Peak
18、 purity and identity can be confirmed using tech-niques such as GC/MS.5. Significance and Use5.1 Promulgations by the Federal Occupational Safety andHealth Administration (OSHA) in 29 CFR 1910 designate thatcertain organic compounds must not be present in workplaceatmospheres at concentrations above
19、 specified values.5.2 This practice, when used in conjunction with PracticeD3686, will promote needed accuracy and precision in thedetermination of airborne concentrations of many of theorganic chemicals given in 29 CFR 1910, CDC-99-74-45,NIOSH Manual of Analytical Methods, OSHA Sampling andAnalytic
20、al Methods, HSE Methods for the Determination ofHazardous Substances, and BGIA GESTIS Analytical Meth-ods. It can be used to determine worker exposures to thesechemicals, provided appropriate sampling periods are used.5.3 Most laboratories are equipped with apparatus similar tothat described in Sect
21、ion 7. Other apparatus can be used whenanalytical procedures suitable for that equipment are em-ployed. The analytical techniques (or variations thereof) de-scribed in Sections 9-11 are in general use to analyze volatileorganic compounds extracted from charcoal. Other procedurescan be used when appr
22、opriate.6. Interferences6.1 Any chemical that produces an FID response and has asimilar retention time as the analyte is a potential interference.If potential interferences were reported when the samples werereceived they should be considered before the samples areextracted. Generally, gas chromatog
23、raphic conditions such asthe type of GC column (phase) or operating parameters can bechanged to resolve interferences.6.2 Selective solvent stripping techniques have been usedsuccessfully to make clean and fast separations of polar,nonpolar and oxygenated compounds. A general guideline isgiven in A1
24、.1 and detailed procedures are given in Refs9(1and 2).6.3 When necessary, the identity or purity of an analyte peakcan be confirmed by GC/mass spectrometry.6.4 The presence of co-adsorbed chemicals can affect therecovery (extraction efficiency) of a particular analyte. Sus-pected effects can be test
25、ed by spiking the analytes on charcoalas in Section 11.7. Apparatus7.1 Gas chromatograph, equipped with a flame ionizationdetector (FID), a temperature-programmable oven, and anautomatic sample injector (autosampler). Sample injection maybe performed manually if necessary. Other detectors (such asel
26、ectron capture, flame photometric, nitrogen phosphorousdetectors) can be used when appropriate but the extractionsolvent may have to be modified.7.2 Electronic data system, or other suitable means to recordand measure detector response, to prepare calibration curves,and to process sample results.7.3
27、 GC columns, required to separate the complex mixtureof possible organic chemicals. Examples of the most commonand useful GC columns are 60-m long, 0.32-mm i.d. fusedsilica capillary GC columns with 0.1 to 1-m thick (df) phasessuch as 100 % dimethyl polysiloxane, 95 % dimethyl-5%diphenyl polysiloxan
28、e, and polyethylene glycol.7.4 Laboratory glassware, calibrated syringes, calibratedsolvent dispensers, assorted Class A pipets and volumetricflasks and glass automatic sample injector (autosampler) vialswith PTFE septum caps to contain analytical standards andsamples.8. Reagents8.1 Analytical stand
29、ards, reagent grade or better, typically97-99+%.8.2 Carbon disulfide, reagent grade or better, typically99.9 % with low benzene content.8.3 Internal standard, reagent grade or better, typically99+%, p-cymene and 1-phenyl hexane are often used. Otherinternal standard reagents can be used providing th
30、at they notappear in air samples and that they are fully tested.8.4 Extraction solvent, usually consists of 0.25 microlitresof internal standard per milliliter of carbon disulfide. Otherextraction solvents can be used provided they are fully tested.(WarningCarbon disulfide is toxic and extremely fla
31、m-mable, as are many of the organic chemicals to be analyzed.Work with these chemicals in a properly functioning laboratoryhood.)9. Calibration9.1 In general, follow the manufacturers manual and safetyinstructions to set up the gas chromatograph. Always use highpurity gases and high quality gas puri
32、fiers.9.2 Install the selected GC column and set the linearvelocity of the carrier gas following manufacturers instruc-tions. Set the injector split ratio at 10:1 or at some otherappropriate ratio. The most commonly used capillary GCcarrier gas is hydrogen. Set the injector, detector, and columnoven
33、 temperatures appropriate for the selected GC column. It isoften useful to heat the GC column at 10-20C below theexpected maximum operating temperature of the column forabout two hours before any analysis is performed. Beforeanalyzing standards or samples, place a fresh septum into theinjection port
34、 of the chromatograph. Replace the septum dailyor when necessary. Septum failure is a frequent cause ofinconsistent FID response and changes in chromatography.9The boldface numbers in parentheses refer to the list of references at the end ofthis standard.D3687 07 (2012)2(WarningHydrogen gas is explo
35、sive and extremely flam-mable. It is absolutely essential that the gas chromatograph beleak free.)9.3 Make sure that the electronic data system is properly setto collect analytical data.9.4 Prepare separate solutions containing 1 mL of eachanalyte per 1 mL of extraction solvent. These solutions areu
36、sed to determine GC column retention time of the analytes.9.5 Analyze these solutions and a reagent blank (withoutcharcoal) using an appropriate GC column and an appropriateoven temperature program to determine GC column retentiontimes for each analyte and for the internal standard. It may beuseful
37、to create an in-house “column map” for each GC columnlisting retention times for each analyte determined using astandard temperature program and a standard carrier gas linearvelocity.9.6 Prepare analytical standards that bracket the expectedrange of sample results for each of the analytes by injecti
38、on ofmicroliter amounts of the analytes into the extraction solution.For example: if the requested analyte is toluene, the air volumesampled with a charcoal tube is 12 L, the density of toluene is0.866 g/mL, the purity of the analytical standard is 99 %, andthe exposure limit (target concentration)
39、is 200 ppm (753mg/m3). Calculate the mass of toluene equivalent to the targetconcentration by multiplying the exposure limit by the charcoalsample air volume (753 mg/m33 0.012 m3= 9.04 mg persample). Prepare a standard at approximately the target con-centration by diluting 10.00 L of toluene to 1.00
40、 mL withextraction solvent. This standard will contain 8.57 mg/mLtoluene (10.00 L 3 0.866 mg/L 3 0.99 pure /1.00 mL).Prepare additional analytical standards at the reporting limit,0.253, 0.53, 1.53, and 2.03 the target concentration. Stan-dards for other analytes can be prepared similarly to toluene
41、using their respective exposure limits, densities, purities ofanalytical standards, and sample air volume (or average airvolume for multiple samples). Different analytes can be pre-pared in the same solution if applicable. Prepare independentanalytical standards with material obtained from a separat
42、evendor to test the purity of the source material and the accuracyof the standard preparation.9.7 Analyze the standards using the same temperatureprogram used in 9.5. Compare the chromatograms to be certainthe analytes are resolved. Generally, chromatographic condi-tions can be altered to separate i
43、nterferences.9.8 Use an internal standard (ISTD) calibration method formost organic compounds. An internal standard calibrationfunction is incorporated with most electronic data systems.Calibration curves for each analyte can be constructed byplotting detector response of standards (y axis) against
44、massper standard (x axis). FID response is usually linear; therefore,linear regression is generally appropriate to find the equation ofthe best-fit line for the calibration curve. Program the datasystem to calculate results in terms of micrograms per sample.This is appropriate because both standards
45、 and samples areprepared in 1.00 mL of extraction solvent. Typically, results forstandards (other than for the reporting limit) calculated fromthe calibration curve will deviate from their theoreticalamounts by not more than 610 %. Usually, deviation for thereporting limit is no more than 625 %. Pre
46、pare and analyzefresh standards as necessary. Analyze a fresh set of calibrationstandards with each sample set, or with a days sequence ofsample sets.10. Sample Preparation10.1 Consider potential analytical interferences that werereported when the samples were received. Make certain thatthe extracti
47、on efficiency (also called desorption efficiency) forall requested analyses has been determined (as described inSection 11) before extracting the samples.10.2 Most charcoal tubes have two sections and eachsection is quantitively transferred to a separate labeled au-tosampler vial. Some charcoal tube
48、s have three sections andeach of the three sections should be similarly transferred to aseparate labeled autosampler vial.10.3 Remove the plastic cap from end of the charcoal withthe back-up section(s) of the sampling tube.10.4 Remove the plug that holds the back-up section inplace and transfer the
49、charcoal to an appropriately labeled vialand close the vial. Similarly transfer the second back-upsection (if present) to a separate labeled vial and close the vial.(A small crochet hook is a convenient device for removing theplugs from the samplers, or a hook can be fashioned from a fine(18 to 20-gauge) steel wire or a 3-in. (76-mm) No. 20hypodermic needle.)10.5 Remove the plug and transfer the front section ofcharcoal to an appropriately labeled vial and close the vial.Check the plugs to make sure that no charcoal adheres to them.Discard the plugs and empty glass tube
