1、Designation: D 6420 99 (Reapproved 2004)Standard Test Method forDetermination of Gaseous Organic Compounds by DirectInterface Gas Chromatography-Mass Spectrometry1This standard is issued under the fixed designation D 6420; the number immediately following the designation indicates the year oforigina
2、l adoption 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 employs a direct interface gaschromatograph/mass
3、 spectrometer (GCMS) to identify andquantify the 36 volatile organic compounds (or sub-set of thesecompounds) listed as follows. The individual Chemical Ab-stract Service (CAS) numbers are listed after each compound.Benzene-71432 Methylene chloride-75092Bromodichloromethane-75274 1,1,2,2-Tetrachloro
4、ethane-79349Carbon disulfide-75150 1,1,1-Trichloroethane-71556Chloroform-67663 1,1,2-Trichloroethane-79005Methyl iso-Butyl ketone-108101 p-Xylene-106423Styrene-100425 Bromomethane-74839Tetrachloroethylene-127184 Carbon tetrachloride-56235Toluene-108883 Chlorobenzene-108907Bromoform-75252 c-1,3-Dichl
5、oropropene-10061015Vinyl acetate-108054 1,2-Dichloroethane-156592Vinyl chloride-75014 1,1-Dichloroethene-75354Chloromethane-74873 t-1,2-Dichloroethene-156605cis-1,2-Dichloroethene-156592 Methyl ethyl ketone-78933Dibromochloromethane-124481 2-Hexanone-5917861,1-Dichloroethane-107062 t-1,3-Dichloropro
6、pene-5427561,2-Dichloropropane-78875 Trichloroethene-79016Ethylbenzene-100414 m-Xylene-108383Ethyl chloride-75003 o-Xylene-954761.2 The test method incorporates a performance-based ap-proach, which validates each GCMS analysis by placingboundaries on the instrument response to gaseous internalstanda
7、rds and their specific mass spectral relative abundance.Using this approach, the test method may be extended toanalyze other compounds.1.3 The test method provides on-site analysis of extracted,unconditioned, and unsaturated (at the instrument) gas samplesfrom stationary sources. Gas streams with hi
8、gh moisturecontent may require conditioning to prevent moisture conden-sation within the instrument. For these samples, quality assur-ance (QA) requirements are provided in the test method tovalidate the analysis of polar, water-soluble compounds.1.4 The instrument range should be sufficient to meas
9、ure thelisted volatile organic compounds from 150 ppb(v) to 100ppm(v), using a full scan operation (between 45 and 300atomic mass units). The range may be extended to higher orlower concentrations using either of the following procedures:1.4.1 The initial three-point calibration concentrations andth
10、e continuing calibration checks are adjusted to match thestack concentrations, or1.4.2 The three-point calibration is extended to includeadditional concentrations to cover the measurement range.1.5 The minimum quantification level is 50 % of the lowestcalibration concentration. Responses below this
11、level areconsidered to be estimated concentrations, unless a calibrationstandard check is conducted at a lower concentration todemonstrate linearity. The sensitivity of the GCMS measure-ment system for the individual target analytes depends upon:1.5.1 The specific instrument response for each target
12、 ana-lyte and the number of mass spectral quantification ionsavailable.1.5.2 The amount of instrument noise, and1.5.3 The percent moisture content of the sample gas.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of th
13、e user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Additional safetyprecautions are described in Section 9.2. Referenced Documents2.1 ASTM Standards:2D 1356 Terminology Relating to Sampling and Analys
14、is ofAtmospheresD 3195 Practice for Rotameter Calibration2.2 EPA Test Methods:Method 1Sample and Velocity Traverses for StationarySources3Method 2Determination of Stack Gas Velocity and Volu-metric Flow Rate (Type S Pitot Tube)31This test method is under the jurisdiction of ASTM Committee D22 onSamp
15、ling and Analysis of Atmospheres and is the direct responsibility of Subcom-mittee D22.03 on Ambient Atmospheres and Source Emissions.Current edition approved October 1, 2004. Published December 2004. Originallyapproved in 1999. Last previous edition approved in 1999 as D 6420 - 99.2For referenced A
16、STM standards, 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.3Code of Federal Regulations 40 CFR Part 60, Appendix A, available fromSuperin
17、tendent of Documents, U.S. Government Printing Office, Washington, DC20402.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Method 3Gas Analysis for Carbon Dioxide, Oxygen, Ex-cess Air, and Dry Molecular Weight3Method 4Determination o
18、f Moisture Content in StackGases3Method 624Purgables43. Terminology3.1 See Terminology D 1356 for definition of terms used inthis test method.3.2 Definitions of Terms Specific to This Standard:3.2.1 blank analysis, ninjecting zero air or nitrogen intothe GCMS to determine background levels of the ta
19、rgetanalytes.3.2.2 CCC, ncontinuing calibration checkinjectingcalibration gas standards into the GCMS to verify the calibra-tion status.3.2.2.1 DiscussionThe continuing calibration check isperformed before each testing day, before resuming samplingafter instrument shutdown or malfunction, and before
20、 resumingsampling after 12 h of continuous instrument operation.3.2.3 quantification ion, na specific ion in the analytesmass spectrum that is used for quantification.3.2.4 system calibration, ncalibration obtained by inject-ing the calibration standard(s) through the entire samplingsystem.3.2.5 sys
21、tem zero, nzero obtained by injecting dry nitro-gen or zero gas through the entire sampling system to deter-mine the system background levels of the target analytes.4. Summary of Test Method4.1 AnalysisVolatile Organic Hazardous Air Pollutants(VOHAP) are analyzed using gas chromatography (GC) tosepa
22、rate the individual compounds and mass spectrometry(MS) to identify the compounds. The MS scans a defined massrange (usually from 45 to 300 atomic mass units (amu) forcombustion sources) to identify the specific fragments for eachmolecule. The target analytes are identified positively by: (1)compari
23、ng eluting analyte GC peak retention times in the totalion chromatograph (TIC) to those contained in a three-pointcalibration, and (2) examining the mass spectral pattern of theeluted peaks. Internal standards are used to correct forhardware-related errors such as different injection volumes,operati
24、onal temperature fluctuations, and electron multiplierdrift.4.2 SamplingSamples are extracted from the stack or ductat a constant rate, filtered, conditioned (if required), andtransported to the GCMS for analysis. Calibration gases areintroduced at the extractive probe outlet, upstream of theprimary
25、 particulate filter.All sample extraction components aremaintained at temperatures that prevent moisture condensationwithin the measurement system components.5. Significance and Use5.1 This field test method determines the mass concentra-tion of VOHAPs (or any subset) listed in Section 1.5.2 Multipl
26、ying the mass concentration by the effluentvolumetric flow rate (see 2.2) yields mass emission rates.5.3 This field test method employs the typical laboratoryGCMS techniques and QA/QC procedures.5.4 This field test method provides data with accuracy andprecision similar to most laboratory GCMS instr
27、umentation.NOTE 1Supporting data are available from ASTM HeadquartersRequest RR:_.6. Interferences6.1 Analytical InterferencesAnalytical interferences oc-cur when chromatographic peak(s) and quantification ion(s)overlap to such an extent that quantification of specific targetcompounds is prohibited.
28、 The nature of the GCMS techniquevirtually eliminates these types of analytical interferences.However, compounds having very simple mass spectra (that is,only one or two mass fragments) may be difficult to identifypositively.6.2 Sampling System InterferencesSampling system inter-ferences occur when
29、target analytes are not transported to theinstrumentation or when compounds damage the measurementsystem components. Water, reactive particulate matter, adsorp-tive sites within the sampling system components, and reactivegases are examples of such potential sampling system interfer-ences. Specific
30、provisions and performance criteria are in-cluded in this test method to detect and prevent the presence ofsampling system interferences.7. Apparatus7.1 Analytical Instrumentation:7.1.1 Gas Chromatograph/Mass Spectrometer (GCMS), ca-pable of separating the analyte mixture and detecting com-pounds in
31、 the 45 to 300 atomic mass unit (amu) range.7.1.2 Personal Computer, with compatible GCMS softwarefor control of the GCMS and for data quantification.7.2 Sampling System:7.2.1 Sampling Probe, glass, stainless steel, or other appro-priate material of sufficient length and physical integrity tosustain
32、 heating, prevent adsorption of analytes, and to reach thegas sampling point.7.2.2 Calibration Assembly, typically fabricated by user, tointroduce calibration standards into the sampling system at theprobe outlet, upstream of the primary particulate filter, at thesame pressure and temperature as tha
33、t of the effluent samples,with provisions for monitoring the sample pressure and tem-perature during continuing calibrations and effluent sampling.7.2.3 Particulate Filters, rated at 0.3 m, placed immedi-ately after the heated probe and after the sample condensersystem.7.2.4 Pump, leak-free, with he
34、ated head, capable of main-taining an adequate sample flow rate (at least 1.5 L/min).7.2.5 Sampling Line, of suitable internal diameter, heated toprevent sample condensation, made of stainless steel, tetrafluo-rocarbon polymer, or other material that minimizes adsorptionof analytes, of minimal lengt
35、h.7.2.6 Sample Condenser System, a refrigeration unit capableof reducing and removing the moisture of the sample gas to alevel acceptable for sample injection.4Code of Federal Regulations 40 CFR Part 136, Appendix A, available fromSuperintendent of Documents, U.S. Government Printing Office, Washing
36、ton, DC20402.D 6420 99 (2004)27.2.7 Sample Flow Rotameters, capable of withstandingsample gas conditions, calibrated in accordance with PracticeD 3195.7.2.8 Sample Transfer Line, to transport sample fromsample interface to GCMS, heated to prevent sample conden-sation and fabricated of stainless stee
37、l, tetrafluorocarbon poly-mer, or other material to minimize adsorption of analytes, ofminimal length.7.3 Auxiliary Equipment:7.3.1 Calibration Gas Manifold, capable of delivering ni-trogen or calibration gases through sampling system or directlyto the instrumentation, with provisions to provide for
38、 accuratedilution of the calibration gases as necessary. See Fig. 1 for anexample schematic.7.3.2 Mass Flow Meters or Controllers, with a statedaccuracy and calibrated range (62 % of scale from 0 to 500mL/min or 0 to 5 L/min).7.3.3 Digital Bubble Meter (or equivalent), having a NIST-traceable calibr
39、ation and accuracy of 62 % of reading, with anadequate range to calibrate mass flow meters or controllers androtameters at the specific flow rates (within 610 %) required toperform the test method.7.3.4 Tubing, tetrafluorocarbon polymer (or other mate-rial), of suitable diameter and length to connec
40、t cylinderregulators and minimize the adsorption of analytes on thetubing surface.7.3.5 Tubing, 316 stainless steel (or other material), ofsuitable diameter and length for heated connections.7.3.6 Gas Regulators, appropriate for individual gas cylin-ders, constructed of materials that minimize adsor
41、ption ofanalytes.8. Reagents and Materials8.1 Calibration Gases, gas standards (in nitrogen balance orother inert gas) for those compounds identified in Section 1,certified by the manufacturer to be accurate to 5 % or better,used for the initial and continuing calibrations.NOTE 2The analytical accur
42、acy of the calibration standards must beknown. The analytical accuracy for gas mixtures may be concentrationdependent.8.2 Internal Standards, manufacturer-certified mixtures forco-injection with sample gas.8.3 High Purity (HP) Nitrogen or Zero Air, for purgingsample lines and sampling system compone
43、nts, dilutions, andblank runs.9. Hazards9.1 Target AnalytesMany of the compounds listed inSection 1 are toxic and carcinogenic. Therefore, avoid expo-sure to these chemicals. Calibration standards are contained incompressed gas cylinders; exercise appropriate safety precau-tions to avoid accidents i
44、n their transport and use.9.2 Sampling LocationThis test method may involvesampling locations with high positive or negative pressures,high temperatures, elevated heights, or high concentrations ofhazardous or toxic pollutants.9.3 Mobile or Remote LaboratoryTo avoid exposure tohazardous pollutants a
45、nd to protect personnel in the laboratory,perform a leak check of the sampling system and inspect thesample exhaust equipment before sampling the calibrationstandards or effluent. Properly vent the exhaust gases.10. Calibration and Standardization10.1 Calibration StandardsBecause of the incompatibil
46、-ity of some target compounds, many gas blends at eachconcentration may be needed to construct a calibration curvefor all of the 36 target analytes listed in 1.1. Obtain or generatecalibration standards of each target compound at nominalconcentrations of 300 ppb(v), 1 ppm(v), and 10 ppm(v) byeither
47、of the following options:FIG. 1 Example Direct Interface GCMS Measurement SystemD 6420 99 (2004)310.1.1 Option 1Obtain calibration gas standards for thetarget compounds at the three specified nominal concentra-tions.10.1.2 Option 2Obtain 10 ppm(v) calibration standardsfor the target analytes. Then s
48、uccessively dilute the 10 ppm(v)standard with ultra-pure nitrogen using mass flow meters.Dilute the 10 ppm(v) standard to 1 ppm(v) and then the 1ppm(v) to 300 ppb(v). If Option 2 is used, analyze thecalibration check (see Table 5) compounds directly as a QAaudit of the dilution technique. The audit
49、result using thecalibrated GCMS must be within 620 % for the calibration tobe valid.10.1.3 Option 2 for preparation of the three-point calibra-tion curve may also generate concentration levels above andbelow the suggested concentration range. It is necessary, whenusing this option, to audit the calibration curve using a certifiedcalibration standard independent from those used to prepare thecurve.10.1.4 If the QA audit results are not within 20 % of theexpected value, corrective action must be taken.10.2 Mass Flow MetersFor Option 2, calibrate the mass
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1