1、Designation: D 3686 08Standard Practice forSampling Atmospheres to Collect Organic CompoundVapors (Activated Charcoal Tube Adsorption Method)1This standard is issued under the fixed designation D 3686; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 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 a method for the sampling ofatmospheres to determine the presence
3、of certain organicvapors by means of adsorption on activated charcoal using acharcoal tube and a small portable sampling pump worn by aworker. A list of some of the organic chemical vapors that canbe sampled by this practice is provided in Annex A1. This listis presented as an information guide and
4、should not beconsidered as absolute or complete.1.2 This practice does not cover any method of samplingthat requires special impregnation of activated charcoal orother adsorption media.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address a
5、ll 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. A specific safetyprecaution is given in 9.4.2. Referenced Doc
6、uments2.1 ASTM Standards:2D 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 3687 Practice for Analysis of Organic Compound VaporsCollected by the Activated Charcoal Tube AdsorptionMethodD 5337 Practice for Flow Rate Calibration of PersonalSampling Pumps2.2 NIOSH Standards:CDC-99-74
7、-45 Documentation of NIOSH Validation Tests3HSM-99-71-31 Personal Sampler Pump for CharcoalTubes; Final Report3NIOSH Manual of Analytical Methods, Fourth Edition42.3 OSHA Standards:29 CFR 1910 Code of Federal Regulations Relating to La-bor, Occupational Safety and Health Administration, De-partment
8、of Labor5OSHA Chemical Sampling Information6OSHA Sampling and Analytical Methods72.4 UK Health and Safety Executive:8Methods for Deter-mination of Hazardous Substances (MDHS)2.5 Berufsgenossenschaftliches Institut fr Arbeitsschulz(BGIA)9GESTIS Analytical Methods3. Terminology3.1 For definitions of t
9、erms used in this method, refer toTerminology D 1356.3.2 Activated charcoal refers to properly conditioned char-coal.4. Summary of Practice4.1 Air samples are collected for organic vapor analysis byaspirating air at a known rate and for an appropriate timethrough sampling tubes containing activated
10、charcoal.4.2 Instructions are given to enable assembly of charcoaltubes suitable for sampling purposes.4.3 Information on the correct use of the charcoal tubesampling device is presented.4.4 Practice D 3687 describes a practice for the analysis ofthese samples.1This practice is under the jurisdictio
11、n of ASTM Committee D22 on Air Qualityand is the direct responsibility of Subcommittee D22.04 on Workplace Air Quality.Current edition approved Dec. 15, 2008. Published January 2009. Originallyapproved in 1978. Last previous edition approved in 2001 as D 3686 - 95(2001)1.2For referenced ASTM standar
12、ds, 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.3Available from National Technical Information Service (NTIS), 5285 PortRoyal Rd., Spring
13、field, VA 22161, http:/www.ntis.gov.4NIOSH Manual of Analytical Methods. http:/www.cdc.gov/niosh/nmam/5Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.6OSHA Chemical Sampling Information
14、. http:/osha.gov/dts/chemicalsampling/toc/toc_chemsamp.html7OSHA Sampling and Analytical Methods. http:/osha.gov/dts/sltc/methods/toc.html8Health Safety Executive. Methods for the Determination of Hazardous Sub-stances (MDHS) guidance. http:/www.hse.gov.uk/pubns/mdhs/index.htm#9Berufsgenossenschaftl
15、iches Institut fr Arbeitsschutz. GESTIS Analyticalmethods. http:/www.hvbg.de/e/bia/gestis/analytical_methods/index.html1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 Promulgations by the U.S. Occupational
16、Safety andHealth Administration (OSHA) in 29 CFR 1910 1910.1000designate that certain organic compounds must not be presentin workplace atmospheres at concentrations above specificvalues.5.2 This practice, when used in conjunction with PracticeD 3687, will provide the needed accuracy and precision f
17、or thedetermination of airborne time-weighted average concentra-tions of many of the organic chemicals cited in CDC-99-74-45,HSM-99-71-31, NIOSH Manual of Analytical Methods,29 CFR 1910 1910.1000, OSHA Chemical Sampling Informa-tion, OSHA Sampling and Analytical Methods, HSE Methodsfor the Determina
18、tion of Hazardous Substances, and BGIAGETIS Analytical Methods.5.3 A partial list of chemicals for which this method isapplicable is given in Annex A1, along with their OSHApermissible exposure limits.6. Interferences6.1 Water mist and vapor can interfere with the collection oforganic compound vapor
19、s. Humidity greater than 60 % canreduce the adsorptive capacity of activated charcoal up to 50 %for some chemicals (1).10Presence of condensed water drop-lets in the sample tube will indicate a suspect sample.6.2 High levels of organic vapors can interfere by reducingthe amount of time a workplace c
20、an be sampled before thecharcoal sampler becomes saturated.7. Apparatus7.1 Charcoal Tube:7.1.1 A sampling tube consists of a length of glass tubingusually containing two sections of activated charcoal that areheld in place and separated by nonadsorbent material. The tubeis sealed at each end.7.1.1.1
21、 Sampling tubes are commercially available. Thetubes are usually divided into two sections with the frontsection containing 100 to 800 mg of activated charcoal and theback section containing 50 to 400 mg of activated charcoal.The 100/50-mg tube (2-4) and Fig. 1) is the one mostfrequently used, it co
22、nsists of a glass tube that is 70-mm long,6-mm outside diameter, 4-mm inside diameter, and containstwo sections of 20/40 mesh-activated coconut-shell charcoalseparated by a 2-mm section of urethane foam. The frontsection of 100 mg is retained by a plug of glass wool, and theback section of 50 mg is
23、retained by either a second 2-mmportion of urethane foam or by a plug of glass wool. Both endsof the tube are usually flame-sealed.NOTE 1Urethane foam is known to adsorb certain pesticides (5).Contaminated urethane foam should not be used for this practice.7.1.1.2 When it is desirable to sample high
24、ly volatilecompounds for extended periods, or at a high volume flow rate,a larger device capable of efficient collection can be used,provided the proportions of the tube and its charcoal contentsare scaled similarly to the base dimensions to provide nomi-nally the same linear flow rate and contact t
25、ime with thecharcoal bed.7.1.2 The back portion of the sampler tube usually contains50 % of the mass of activated charcoal present in the frontsection. The back section adsorbs vapors that penetrate thefront section and serves as a warning that breakthrough mayhave occurred. (Annex A1 gives recommen
26、ded maximum tubeloading information for many chemicals.)7.1.3 The adsorptive capacity and extraction efficiency (alsocalled desorption efficiency) of different batches of activatedcharcoal can vary. Commercial tubes, if used, should bepurchased from the same batch and in sufficient number toprovide
27、sampling capability for an adequate period of time.Care must be taken to have enough tubes from the same batchfor a given study.7.1.4 Pressure drop across the sampling tube should be lessthan 25 mm Hg (3.3 kPa) at a flow rate of 1000 mL/min andless than 4.6 mm Hg (0.61 kPa) at a flow rate of 200 mL/
28、min.7.1.5 Charcoal sampling tubes prepared in accordance withthis practice and with sealed glass ends can be stored indefi-nitely. Accrediting bodies, such as American Industrial Hy-giene Association, may require that sampling media have anexpiration date. Accredited facilities must abide by this da
29、te.7.2 Sampling Pumps:7.2.1 Any pump with a flow rate that can be accuratelydetermined, that can be set at the desired sampling rate, andthat can maintain the desired sampling rate for a sufficient timeis suitable. Primarily though, this practice is intended for usewith small personal sampling pumps
30、.10The boldface numbers in parentheses refer to the list of references at the endof this standard.FIG. 1 Activated Charcoal Adsorption Sampling TubeD36860827.2.2 Pumps having stable low flow rates (10 to 200mL/min) are preferable for long period sampling (up to 8 h) orwhen the concentration of organ
31、ic vapors is expected to behigh. Reduced sample volumes will avoid exceeding theadsorptive capacity of the charcoal tubes. (Suggested flow ratesand sampling times are given in Annex A1 for anticipatedconcentration ranges.) (Sample volumes are discussed in 9.5.)7.2.3 Pumps are available that will pro
32、vide stable flow ratesbetween 65 % of the desired flow rate. Pumps should becalibrated before and after sampling.7.2.4 All sampling pumps must be carefully calibrated withthe charcoal tube device in the proper sampling position.7.2.5 A sampling tube holder with flexible tubing is used toconnect the
33、sampling tube to the sampling pump. The samplingtube holder is used to protect the worker from the sharp end ofthe samping tube.8. Reagents8.1 Activated CharcoalPrior to being used to make sam-pling devices the charcoal should be heated in an inert gas at anappropriate temperature for a sufficient t
34、ime. Commerciallyavailable coconut-shell charcoal (20/40 mesh) has been foundto have adequate adsorption capacity for many volatile chemi-cals. Other charcoals, such as JXC charcoal, petroleum-basedcharcoal, and proprietary charcoals, can be used for appropriateapplications.9. Sampling with Activate
35、d Charcoal Samplers9.1 Calibration of the Sampling SystemCalibrate the sam-pling system, including pump, flow regulator, tubing to beused, and a representative charcoal tube (or an equivalentinduced resistance) with a primary flow-rate standard or with acalibrated secondary standard to within 65 % o
36、f the desiredflow rate as described in Practice D 5337. Calibrate thesampling pump in a clean location with similar temperatureand barometric pressure as the sampling site. Normally, cali-brated pump flow rates or sample air volumes are not correctedfor temperature or barometric pressure.9.2 Break o
37、pen both ends of the charcoal tube to be used forsampling, ensuring that each opening is at least one half theinside diameter of the tube.9.3 Insert the charcoal tube into the connective flexibletubing, placing the back-up section nearest to the pump. At notime should there be any tubing ahead of th
38、e sampling tubes.Use a sampling tube holder to protect the worker from thesharp end of the sampling tube.9.4 For a breathing zone sample, fasten the sampling pumpto the worker, and attach the sampling tube as close to theworkers breathing zone as possible. Position the tube in avertical position to
39、avoid channeling of air through the charcoalsections. (WarningAssure that the presence of the samplingequipment is not a safety hazard to the worker and that theequipment will not interfere with the workers duties.)9.4.1 Turn on the pump.9.4.2 Record the flow rate, the starting time, and dependingon
40、 the make of pump used, the register reading.9.5 Sampling VolumesThe minimum sample volume willbe governed by the detection limit of the analytical method,and the maximum sample volume will be determined by eitherthe adsorptive capacity of the charcoal or limitations of thepump battery.9.5.1 One met
41、hod of calculating required sample volumes isto determine first the concentration range, over which it isimportant to report an exact number, for example from 0.2 to2 times the permissible exposure concentration, and thencalculate the sample volumes as follows:D3686083Minimum sample volume, m35 (1)m
42、inimum detection limit, mg0.2 3 permissible exposure limit, mg/m3Maximum sample volume, m35 (2)tube capacity for vapors, mg2 3 permissible exposure limit, mg/m39.5.2 Select a sampling rate that, in the sampling timedesired, will result in a sample volume between the minimumand maximum calculated in
43、9.5.1.9.5.2.1 Generally a long sampling time at a low flow rate ispreferable to short-term, high-volume sampling. This is con-sistent with the fact that most health standards are based on8-h/day time-weighted averages of exposure concentrations.Often, two 4-h samples are preferable to a single 8-h s
44、ample sothat if one is lost then the other can be used to partiallydocument exposure. Work practices may change during the dayand be better documented with two samples.9.5.2.2 Asample flow rate of less than 10 mL/min, however,should not be used. Calculations based upon diffusion coeffi-cients for se
45、veral representative compounds indicate thatsampling at less than 10 mL/min may not give accurateresults.119.5.2.3 Sampling information for a large number of organicchemicals is given in Annex A1, in the NIOSH Manual ofAnalytical Methods, OSHA Chemical Sampling Informationfile and methods, UK HSE MD
46、HS database, and GermanBGIA GESTIS Analytical Methods database. Other appropri-ate sources of information and guidance, including Annex A1,can also be used.9.5.3 When spot checks are being made of an environment,a sample volume of 10 L is adequate for determining vaporconcentrations in accordance wi
47、th exposure guidelines. Par-ticularly volatile organic chemicals may require a lesser samplevolume to prevent sampler saturation. Consult the abovesources for sampling information before sampling.9.6 At the end of the sampling period, turn off the pump,and record all pertinent information: time, reg
48、ister reading, andif pertinent, sampling site temperature, barometric pressure,and relative humidity.9.6.1 Seal the charcoal tube with the plastic caps provided.9.6.2 Label the tube with the appropriate information toidentify it.9.7 At least one charcoal sampling tube should be presentedfor analysis
49、 as a field blank with every 10 or 15 samples, or foreach specific inspection or field study.9.7.1 Break the sealed ends off the field blank tube and capit with the plastic caps. Do not draw air through the blank tube,but in all other ways treat it as an air sample.9.7.2 The purpose of the field blank is to assure that if thesampling tubes adsorb vapors extraneous to the samplingatmosphere, the presence of the contaminant will be detectedon the field blank.9.8 Calculation of Sample Volume:9.8.1Sample volume, mL 5 calibrated pump flow rate mL/min!3 sampling time min
