1、Designation: D6196 151Standard Practice forChoosing Sorbents, Sampling Parameters and ThermalDesorption Analytical Conditions for Monitoring VolatileOrganic Chemicals in Air1This standard is issued under the fixed designation D6196; the number immediately following the designation indicates the year
2、 oforiginal adoption 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.1NOTEEditorial corrections were made throughout in July 2018.1. Scop
3、e1.1 This practice is intended to assist in the selection ofsorbents and procedures for the sampling and analysis ofambient (1),2indoor (2), and workplace (3, 4) atmospheres fora variety of common volatile organic compounds (VOCs). Itmay also be used for measuring emissions from materials insmall or
4、 full scale environmental chambers or for humanexposure assessment.1.2 This practice is based on the sorption of VOCs from aironto selected sorbents or combinations of sorbents. Sampledair is either drawn through a tube containing one or a series ofsorbents (pumped sampling) or allowed to diffuse, u
5、ndercontrolled conditions, onto the sorbent surface at the samplingend of the tube (diffusive or passive sampling). The sorbedVOCs are subsequently recovered by thermal desorption andanalyzed by capillary gas chromatography.1.3 This practice applies to three basic types of samplersthat are compatibl
6、e with thermal desorption: (1) pumpedsorbent tubes containing one or more sorbents; (2) axialpassive (diffusive) samplers (typically of the same physicaldimensions as standard pumped sorbent tubes and containingonly one sorbent); and (3) radial passive (diffusive) samplers.1.4 This practice recommen
7、ds a number of sorbents that canbe packed in sorbent tubes for use in the sampling ofvapor-phase organic chemicals; including volatile and semi-volatile organic compounds which, generally speaking, boil inthe range 0 to 400C (v.p. 15 to 0.01 kPa at 25C).1.5 This practice can be used for the measurem
8、ent ofairborne vapors of these organic compounds over a wideconcentration range.1.5.1 With pumped sampling, this practice can be used forthe speciated measurement of airborne vapors of VOCs in aconcentration range of approximately 0.1 g/m3to 1 g/m3, forindividual organic compounds in 110 L air sampl
9、es. Quanti-tative measurements are possible when using validated proce-dures with appropriate quality control measures.1.5.2 With axial diffusive sampling, this practice is valid forthe speciated measurement of airborne vapors of volatileorganic compounds in a concentration range of approximately100
10、 g/m3to 100 mg/m3for individual organic compounds foran exposure time of8hor1g/m3to 1 mg/m3for individualorganic compounds for an exposure time of four weeks.1.5.3 With radial diffusive sampling, this practice is validfor the measurement of airborne vapors of volatile organiccompounds in a concentra
11、tion range of approximately 5 g/m3to 5 mg/m3for individual organic compounds for exposuretimes of one to six hours.1.5.4 The upper limit of the useful range is almost alwaysset by the linear dynamic range of the gas chromatographcolumn and detector, or by the sample splitting capability ofthe analyt
12、ical instrumentation used.1.5.5 The lower limit of the useful range depends on thenoise level of the detector and on blank levels of analyte orinterfering artifacts (or both) on the sorbent tubes.1.6 This procedure can be used for personal and fixedlocation sampling. It cannot be used to measure ins
13、tantaneousor short-term fluctuations in concentration. Alternative grabsamplingprocedures using canister air samplers (for example,Test Method D5466) may be suitable for monitoring instanta-neous or short term fluctuations in air concentration. Alterna-tives for on-site measurement include, but are
14、not limited to,gas chromatography, real-time mass spectrometry detectorsand infrared spectrometry.1.7 The sampling method gives a time-weighted averageresult.1.8 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1This practice is
15、under the jurisdiction ofASTM Committee D22 on Air Qualityand is the direct responsibility of Subcommittee D22.05 on Indoor Air.Current edition approved Nov. 1, 2015. Published February 2016. Originallyapproved in 1997. Last previous edition approved in 2009 as D6196 03 (2009).DOI: 10.1520/D6196-15E
16、01.2The bold face numbers in parentheses refer to the list of references at the endof this practice.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized
17、 principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.11.9 This standard does not purport to address all of thesafety concer
18、ns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.10 This international standard was developed in accor-dance with i
19、nternationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3D
20、1356 Terminology Relating to Sampling and Analysis ofAtmospheresD3670 Guide for Determination of Precision and Bias ofMethods of Committee D22D3686 Practice for Sampling Atmospheres to Collect Or-ganic Compound Vapors (Activated Charcoal Tube Ad-sorption Method)D5466 Test Method for Determination of
21、 Volatile OrganicCompounds in Atmospheres (Canister Sampling Method-ology)E355 Practice for Gas Chromatography Terms and Relation-ships2.2 ISO Standards:4ISO 5725 Accuracy (Trueness and Precision) of Measure-ment Methods and ResultsISO 6145-10 Gas Analysis. Preparation of Calibration GasMixtures. Pe
22、rmeation MethodISO 13137 Workplace Atmospheres: Pumps for PersonalSampling of Chemical and Biological Agents. Require-ments and Test MethodsISO 16017-1 Indoor, Ambient, and Workplace Air Sam-pling and Analysis of Volatile Organic Compounds bySorbent Tube/Thermal Desorption/Capillary Gas Chroma-togra
23、phy Part 1: Pumped SamplingISO 16017-2 Indoor, Ambient, and Workplace Air Sam-pling and Analysis of Volatile Organic Compounds bySorbent Tube/Thermal Desorption/Capillary Gas Chroma-tography Part 2: Diffusive SamplingISO 16107 Workplace AtmospheresProtocol for Evaluat-ing the Performance of Diffusiv
24、e SamplersISO GUM Guide to the Expression of Uncertainty in Mea-surement2.3 CEN Standards:5EN 482 Workplace Atmospheres: General Requirements forthe Performance of Procedures for the Measurement ofChemical AgentsEN 838 Workplace Atmospheres: Requirements and TestMethods for Diffusive Samplers for th
25、e Determination ofGases and VapoursEN 1076 Workplace Atmospheres: Pumped Sorbent Tubesfor the Determination of Gases and Vapours. Require-ments and Test MethodsEN 13528-3 Ambient Air QualityDiffusive Samplers forthe Determination of Concentrations of Gases and Va-pours Part 3: Guide to Selection, Us
26、e, and MaintenanceEN 14662-1 Ambient Air Quality Standard Method forMeasurement of Benzene Concentrations Part 1:Pumped Sampling Followed by Thermal Desorption andGas ChromatographyEN 14662-4 Ambient Air Wuality Standard Method forMeasurement of Benzene Concentrations Part 4: Diffu-sive Sampling Fol
27、lowed by Thermal Desorption and GasChromatography2.4 EPA Method:6EPAMethodTO-17 Determination ofVolatile Organic Com-pounds in Ambient Air Using Active Sampling OntoSorbent Tubes3. Terminology3.1 DefinitionsRefer to Terminology D1356 and PracticeE355 for definitions of terms used in this practice.3.
28、2 Definitions of Terms Specific to This Standard:3.2.1 breakthrough volumethe volume of a known atmo-sphere that can be passed through the tube before the concen-tration of the vapor eluting from non-sampling end of the tubereaches 5 % of the applied test concentration.3.2.2 desorption effciencythe
29、ratio of the mass of analytedesorbed from a sampling device to that applied.3.2.3 diffusive (passive) samplera device that is capable ofcollecting gases and vapors from an atmosphere at ratescontrolled by gaseous diffusion through a static air layer(diffusion gap), permeation through a membrane or s
30、ome otherdiffusion-barrier, but which does not involve the active move-ment of air through the sampler.3.2.4 axial diffusive samplera tube-form device with pre-cisely controlled dimensions that samples gaseous organicchemicals in air diffusively through one end of the tube ontothe sorbent surface he
31、ld inside the tube at a fixed distance fromthe sampling end.3.2.5 radial diffusive samplera tube form device whichallows controlled diffusive sampling around the walls of thesampler; that is, parallel to the radius. The ends of a radialsampler are sealed.3.2.6 diffusive uptake rate or diffusive samp
32、ling rate (U)the rate at which the diffusive sampler collects a particular gasor vapor from the atmosphere, expressed in nanograms perparts per million (volume/volume) per minute (ng.ppm-1(V/V)3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
33、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.5Available from European Committee for St
34、andardization (CEN), 36 rue deStassart, B-1050, Brussels, Belgium, http:/www.cenorm.be.6Available from United States Environmental ProtectionAgency (EPA), WilliamJefferson Clinton Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460,http:/www.epa.gov.D6196 1512min-1), picograms per parts per bill
35、ion (volume/volume) perminute (pg.ppb-1(V/V) min-1), or cubic centimetres per minute(cm3/min).3.2.7 loadingthe mass of analyte collected or introducedon the sampler.3.2.8 pumped samplera device which is capable of takingsamples of gases and vapors from the atmosphere and consist-ing of a sampling me
36、dium, such as a sorbent tube, and an airsampling pump.Air is passed through the sorbent tube at a ratecontrolled by the sampling pump.3.2.9 safe sampling volume70 % of breakthrough volume(3.2.1) or 50 % of the chromatographically-determined reten-tion volume.3.2.10 sorbent strengthterm to describe t
37、he affinity ofsorbents for VOCs; a stronger sorbent is one which offersgreater safe sampling volumes for VOCs relative to another,weaker, sorbent.3.2.11 sorbent tubea tube, usually made of metal or glass,containing one or more sorbents or a reagent-impregnatedsupport which may be used to collect vap
38、or-phase organicchemicals either by passing air through the tube at a ratecontrolled by an air sampling pump (pumped sampling) or byallowing controlled diffusion of gases or vapors onto thesorbent sampling surface (diffusive or passive sampling).3.3 Definitions of Acronyms Used in This Standard toDe
39、note Specific Types or Classes of Sorbent (See Also forDetails and Examples):3.3.1 PDMSPolydimethyl siloxane-based sorbent (GCcolumn packing material), typically comprising polydimethylsiloxane gum coated on particles of inert support at a specifiedloading levels: for example,3%or10%.3.3.2 VW-GCBVer
40、y weak graphitized carbon black sor-bent.3.3.3 W-PPWeak porous polymer sorbent.3.3.4 WM-GCBWeak to medium strength graphitized car-bon black sorbent.3.3.5 M-PPMedium strength porous polymer sorbent.3.3.6 MS-GCBMedium to strong graphitized carbon blacksorbent.3.3.7 CMSCarbonized molecular sieve sorbe
41、nt.4. Summary of Practice4.1 For active (pumped) sampling, a suitable sorbent orseries of sorbents is selected for the compound or mixture to besampled. The sorbents selected are arranged in series, in orderof increasing sorbent strength from the sampling end. This canbe done by linking together tub
42、es containing the individualsorbents or by packing a single tube with two or more sorbents.Provided suitable sorbents are chosen, volatile organic compo-nents are retained by the sorbent tube(s) and thus are removedfrom the flowing air stream. The use of weaker sorbents infront of stronger sorbents
43、during sampling prevents irreversibleadsorption of higher boiling compounds on the strongersorbents.4.2 For axial diffusive sampling, a suitable sorbent isselected for the compound or mixture to be sampled. If morethan one sorbent is required, two or more diffusive samplingtubes, packed with differe
44、nt sorbents, are used in parallel. Thediffusive sampler or samplers are exposed to the atmospherefor a measured time period. Provided the sorbents chosen arestrong enough to maintain a zero (or negligible) analyteconcentration at the sampling surface (that is, to minimize backdiffusion), Ficks law o
45、f diffusion will apply. The uptake rate ofeach volatile organic component, in terms of mass retained perunit of ambient air concentration per unit exposure time, willbe a constantUsee3.2.4. This means that, while Ficks lawapplies and back-diffusion remains negligible, the analyte masscollected by th
46、e sampler is directly proportional to the timeweighted average atmospheric concentration over a givenexposure period.4.3 For radial diffusive sampling, a suitable sorbent isselected for the compound or mixture to be sampled. If morethan one sorbent is required, two or more samplers, packedwith diffe
47、rent sorbents, are used in parallel. The diffusivesampler or samplers are exposed to the atmosphere for ameasured time period. Provided the sorbents chosen are strongenough to maintain a zero (or negligible) analyte concentrationat the sampling surface (that is, to minimize back diffusion),Ficks law
48、 of diffusion will apply and the uptake rate of eachvolatile organic component, in terms of mass retained per unitexposure time, is directly proportional to the atmosphericconcentration.4.4 The collected vapor (on each tube or cartridge) isdesorbed by heat and is transferred under inert carrier gas
49、intoa gas chromatograph (GC) equipped with a capillary columnand either a conventional detector (such as the flame ionizationor electron capture detector (ECD) or a mass spectrometricdetector, where it is analyzed. A sample focusing trap betweenthe sampling tube and the gas chromatograph is commonlyemployed to ensure injection of the analytes in as small avolume of carrier gas as possible, providing better peakresolution and sensitivity than is normally achievable withsingle stage desorption. Where the sample to be analyze
