1、Designation: D 5466 01 (Reapproved 2007)Standard Test Method forDetermination of Volatile Organic Chemicals inAtmospheres (Canister Sampling Methodology)1This standard is issued under the fixed designation D 5466; the number immediately following the designation indicates the year oforiginal adoptio
2、n or, in the case of revision, 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 a procedure for sampling andanalysis of volatil
3、e organic compounds (VOCs) in ambient,indoor, or workplace atmospheres. The test method is based onthe collection of air samples in stainless steel canisters withspecially treated (passivated) interior surfaces. For sampleanalysis, a portion of the sample is subsequently removed fromthe canister and
4、 the collected VOCs are selectively concen-trated by adsorption or condensation onto a trap, subsequentlyreleased by thermal desorption, separated by gas chromatog-raphy, and measured by a mass spectrometric detector or otherdetector(s).This test method describes procedures for samplinginto canister
5、s to final pressures both above and below atmo-spheric pressure (respectively referred to as pressurized andsubatmospheric pressure sampling).21.2 This test method is applicable to specific VOCs thathave been tested and determined to be stable when stored incanisters. Numerous compounds, many of whi
6、ch are chlori-nated VOCs, have been successfully tested for storage stabilityin pressurized canisters (1-4).3Although not as extensive,documentation is also available demonstrating stability ofVOCs in subatmospheric pressure canisters. While initialstudies were concentrated on non-polar VOCs, inform
7、ation onstorage stability has been extended to many polar compoundsas well (5-7).1.3 The procedure for collecting the sample involves the useof inlet lines and air filters, flow rate regulators for obtainingtime-integrated samples, and in the case of pressurizedsamples, an air pump. Canister sampler
8、s have been designed toautomatically start and stop the sample collection process usingelectronically actuated valves and timers (8-10). A weather-proof shelter is required if the sampler is to be used outside.1.4 The organic compounds that have been successfullymeasured at single-digit parts-per-bi
9、llion by volume (ppbv)levels with this test method are listed in Table 1. This testmethod is applicable to VOC concentrations ranging from thedetection limit to 300 ppbv. Above this concentration, samplesrequire dilution with dry ultra-high-purity nitrogen or air.1.5 This standard does not purport t
10、o 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. Safety practicesshould be part of the users SOP ma
11、nual.2. Referenced Documents2.1 ASTM Standards:4D 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 1357 Practice for Planning the Sampling of the AmbientAtmosphereE 260 Practice for Packed Column Gas ChromatographyE 355 Practice for Gas Chromatography Terms and Rela-tionships2.2 Oth
12、er Documents:U.S. Environmental Protection Agency, Compendium ofMethods for the Determination to Toxic Organic Com-pounds in Ambient Air, Method TO-14A, EPA 600/R-96/010b53. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D 1356. Other pertinent abbre
13、-viations and symbols are defined within this practice at point ofuse.3.2 Definitions of Terms Specific to This Standard:1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.05 on Indoor Air.Current edition approved Apri
14、l 1, 2007. Published June 2007. Originallyapproved in 1993. Last previous edition approved in 2001 as D 5466 - 01.2This test method is based on EPA Compendium Method TO-14, “TheDetermination of Volatile Organic Compounds (VOCs) in Ambient Air UsingSUMMA Passivated Canister Sampling and Gas Chromatog
15、raphic Analysis,” May1988.3The boldface numbers in parentheses refer to the list of references at the endof the standard.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refe
16、r to the standards Document Summary page onthe ASTM website.5Available from the U.S. Dept. of Commerce, National Technical InformationService, Port Royal Road, Springfield, VA 22161 or http:/www.cpa.gov/ttn/amtic/airtox.html.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Con
17、shohocken, PA 19428-2959, United States.3.2.1 absolute canister pressurePg+Pa, where Pg= gage pressure in the canister. (kPa, psi) and Pa = barometricpressure.3.2.2 absolute pressurepressure measured with referenceto absolute zero pressure (as opposed to atmospheric pressure),usually expressed as kP
18、a, mm Hg, or psia.3.2.3 certificationthe process of demonstrating with hu-mid zero air and humid calibration gases that the samplingsystems components and the canister will not change theconcentrations of sampled and stored atmospheres.3.2.4 cryogena refrigerant used to obtain very low tem-peratures
19、 in the cryogenic trap of the analytical system. Atypical cryogen is liquid argon (bp 185.7C) or liquid nitro-gen (bp 195C).3.2.5 dynamic calibrationcalibration of an analytical sys-tem using calibration gas standard concentrations generated bydiluting known concentration compressed gas standards wi
20、thpurified, humidified inert gas.3.2.5.1 DiscussionSuch standards are in a form identicalor very similar to the samples to be analyzed. Calibrationstandards are introduced into the inlet of the sampling oranalytical system in the same manner as authentic fieldsamples.3.2.6 gage pressurepressure meas
21、ured above ambient at-mospheric pressure (as opposed to absolute pressure). Zerogage pressure is equal to ambient atmospheric (barometric)pressure.3.2.7 megabore columnchromatographic column havingan internal diameter (I.D.) greater than 0.50 mm.3.2.7.1 DiscussionThe Megabore column is a trademarkof
22、 the J however, manypolar compounds are not identified using this drying procedure.Sample is routed through a chromatographic valve, then into acryogenic trap. Concentration of compounds based upon apreviously installed calibration table is reported by an auto-mated data reduction program. In full s
23、can mode the GC/MSacquires mass spectral data by continuously scanning a rangeof masses typically between 18 and 250 amu. A SIM system isprogrammed to acquire data for only the target compounds andto disregard all others. The sensitivity is typically 1 ppbv orbetter for a 500 mL air sample.10.1.1.2
24、SIM analysis is based on a combination of reten-tion times and relative abundances of selected ions (see Table2). These qualifiers are stored on the hard disk of the GC/MScomputer and are compared to sample data for identification ofeach chromatographic peak. The retention time qualifier isdetermine
25、d to be, for example 60.10 min of the libraryretention time of the compound. The acceptance level forrelative abundance is determined to be, for example 615 % ofthe expected abundance, except for vinyl chloride and meth-ylene chloride, which is determined to be, for example 625 %.Three ions are meas
26、ured for most of the forty compounds.When compound identification is made by the computer, anypeak that fails any of the qualifying tests is flagged (forexample, with an asterisk). All the data shall be manuallyexamined by the analyst to determine the reason for the flagand whether the compound can
27、be reported as found. Whilethis adds some subjective judgment to the analysis, computer-generated identification problems must be clarified by anexperienced operator. Manual inspection of the quantitativeresults must also be performed to verify concentrations outsidethe expected range.To realize the
28、 maximum sensitivity of SIM,retention time windows shall be chosen for each compound orgroup of compounds so that the number of ions monitoredduring a scan is kept to three or four.10.1.1.3 A permeable membrane dryer may be used toremove water vapor selectively from the sample stream. Thepermeable m
29、embrane consists of tubing made of a copolymerof tetrafluoroethylene and fluorosulfonyl monomer that iscoaxially mounted within larger tubing. The sample stream ispassed through the interior of the permeable membrane tubing,allowing water (and other light, polar compounds) to permeatethrough the wal
30、ls into a dry air purge stream flowing throughthe annular space between the semipermeable membrane andouter tubing. To prevent excessive moisture build-up and anymemory effects in the dryer, a cleanup procedure involvingperiodic heating of the dryer (100C for 20 min) while purgingwith dry zero air (
31、500 mL/min) shall be implemented as part ofthe users standard operating procedure (SOP) manual. Theclean-up procedure is repeated during each analysis. However,care must be taken when heating the dryer (21). Anothermethod for drying the air sample involves freezeout of water ina pre-trap followed by
32、 raising the temperature and purgingtarget compounds that move into the gas phase to a down-stream trap while leaving most of the water behind. Removalof water with a permeable membrane-type dryer shall not beperformed for compounds other than those on the list in Table1 unless recovery studies are
33、performed to validate analysis ofthese compounds. Polar compounds are particularly suscep-tible to loss through the permeable membrane interface.NOTE 14A cleanup procedure is particularly useful when employingcryogenic preconcentration of VOCs with subsequent GC analysis be-cause excess accumulated
34、water can cause trap and column blockage andalso adversely affect detector precision. This is a particular problem usingGC/MSD systems. In addition, the improvement in water removal fromthe sampling stream will allow analyses of much larger volumes of sampleair in the event that greater system sensi
35、tivity is required for targetedcompounds.NOTE 15While a differentially pumped GC/MS analytical systemdoes not need a permeable membrane dryer for drying the sample gasstream, such a dryer may be used with GC/Mass Selective Detector(GC/MSD) type GC/MS systems because GC/MSD units are far moresensitiv
36、e to excessive moisture than the GC/MS analytical systems.Moisture can adversely affect detector precision.10.1.1.4 The cryogenic sample trap is heated to at least120C and no more than 200C in approximately 60 s and theanalyte is injected onto the capillary column. Rapid heating ofthe trap provides
37、efficient transfer of the sample componentsonto the gas chromatographic column. Upon sample injectiononto the column, the MS computer is signaled by the GCcomputer to begin detection of compounds which elute fromthe column. The gas stream from the GC is scanned within apreselected range of atomic ma
38、ss units (amu). For detection ofcompounds in Table 1, the range shall be 18 to 250 amu,resulting in a 1.5 Hz repetition rate. Six scans per elutingchromatographic peak are provided at this rate. Automatedcomputer peak selection, or manual selection of each targetcompound is performed according to th
39、e instrument manufac-turers specifications.Alibrary search is then performed and upto ten of the best matches for each peak are listed.Aqualitativecharacterization of the sample is provided by this procedure.10.1.1.5 Packed metal tubing is used for reduced tempera-ture trapping of VOCs. The cooling
40、unit is comprised of a 32mm outside diameter (O.D.) nickel tubing loop packed with6080 mesh borosilicate glass beads.D 5466 01 (2007)12NOTE 16The nickel tubing loop can be placed in an aluminum orbrass block containing a tube heater (500 to 1000 watt) or wound onto acylindrically formed tube heater
41、(250 watt).Acartridge heater (25 watt) isrequired for the cylindrically wound trap. This low watt heater issandwiched between pieces of metal plate at the trap inlet and outlet toprovide additional heat to eliminate cold spots in the transfer tubing.Rapid heating (178 to +120C in 55 s) is accomplish
42、ed by direct thermalcontact between the heater and the trap tubing. Cooling of aluminum orbrass mounted traps is achieved by immersion in liquid cryogen. Coolingof cylindrically wound traps is achieved by vaporization around orsubmersion of the trap in the cryogen. In the shell, efficient cooling (
43、+120to 178C in 225 s) is facilitated by confining the vaporized cryogen to thesmall open volume surrounding the trap assembly. The trap assembly andchromatographic valve are mounted on a baseplate fitted into the injectionand auxiliary zones of the GC on an insulated pad directly above thecolumn ove
44、n when used with the Hewlett-Packard 5880 GC.10.1.1.6 As an option, the analyst may wish to split the gasstream exiting the column with a low dead-volume tee, passingone-third of the sample gas (1.0 mL/min) to the mass selectivedetector and the remaining two-thirds (2.0 mL/min) through aflame ioniza
45、tion detector. The use of the specific detector(MS-SCAN) coupled with the nonspecific detector (FID)enables enhancement of data acquired from a single analysis.In particular, the FID provides the user with the following:(1) Semi-real time picture of the progress of the analyticalscheme,(2) Confirmat
46、ion by the concurrent MS analysis of otherlabs that can provide only FID results, and(3) Ability to compare GC-FID with other analyticallaboratories with only GC-FID capability.10.2 GC/MS-SCAN-SIM System Performance Criteria:10.2.1 GC/MS System Operation:10.2.1.1 Prior to analysis, assemble and chec
47、k the GC/MSsystem according to manufacturers instructions.10.2.1.2 Table 3 outlines general operating conditions forthe GC/MS-SCAN-SIM system with optional FID.10.2.1.3 Challenge the GC/MS system with humid zero air(see 11.2.2). Results of this challenge must indicate less than0.2 ppbv of targeted V
48、OCs prior to sample analysis.10.2.2 Daily GC/MS Tuning:10.2.2.1 At the beginning of each day or prior to a calibra-tion, tune the GC/MS system to verify that acceptable perfor-mance criteria are achieved.10.2.2.2 For tuning the GC/MS, introduce gas from acylinder containing 4-bromofluorobenzene by w
49、ay of a sampleloop valve injection system. Obtain a background correctedmass spectrum of 4-bromofluorobenzene and check that all keyion abundance criteria are met. BFB calibration requirementsare listed in Table 4. If the criteria are not achieved, the analystshall retune the mass spectrometer and repeat the test until allcriteria are achieved. Some systems are configured for auto-tuning to facilitate this process.10.2.2.3 If any key ion abundance observed for the daily4-bromofluorobenzene mass tuning check differs by more than10 % absolute abundance from
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