1、Designation: D 6877 03Standard Test Method forMonitoring Diesel Particulate Exhaust in the Workplace1This standard is issued under the fixed designation D 6877; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. 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 covers determination of organic andelemental carbon in the particulate fraction of diesel engineexhaust, herea
3、fter referred to as diesel particulate matter(DPM). Samples of workplace atmospheres are collected onquartz-fiber filters. The method also is suitable for other typesof carbonaceous aerosols, but it is not appropriate for samplingvolatile or semi-volatile components. These components re-quire sorben
4、ts for efficient collection.NOTE 1Sample collection and handling procedures for environmentalsamples differ from occupational samples. This standard addresses occu-pational monitoring of DPM in workplaces where diesel-powered equip-ment is used.1.2 The method is based on a thermal-optical technique
5、(1,2)2. Speciation of organic and elemental carbon is achievedthrough temperature and atmosphere control, and an opticalfeature that corrects for sample charring.1.3 A portion of a 37-mm, quartz-fiber filter sample isanalyzed. Results for the portion are used to calculate the totalmass of organic an
6、d elemental carbon on the filter. The portionmust be representative of the entire filter deposit. If the depositis uneven, two or more representative portions should beanalyzed for an average. Open-faced cassettes give evendeposits but are often not practical. Closed-face cassettes giveequivalent re
7、sults if other dusts are absent. Other samplers maybe required, depending on the sampling environment (2-5).1.4 The calculated limit of detection (LOD) depends on thelevel of contamination of the media blanks (5). A LOD ofapproximately 0.2 g carbon per cm2of filter was estimatedwhen analyzing a sucr
8、ose standard solution applied to filterportions cleaned immediately before analysis. LODs based onmedia blanks stored after cleaning are usually higher. LODsbased on a set of media blanks from a commercial laboratorywere OC = 1.2 g/cm2, EC = 0.4 g/cm2, and TC = 1.3 g/cm2,where OC, EC, and TC refer t
9、o organic, elemental, and totalcarbon, respectively.1.5 OC-EC methods are operational, which means theanalytical procedure defines the analyte. The test method offersgreater selectivity and precision than thermal techniques thatdo not correct for charring of organic components. The analysismethod is
10、 simple and relatively quick (about 15 min). Theanalysis and data reduction are automated, and the instrumentis programmable (different methods can be saved as methodsfor other applications).1.6 A method (5040) for DPM based on thermal-opticalanalysis has been published by the National Institute for
11、Occupational Safety and Health (NIOSH). Method updates (3,4) have been published since its initial (1996) publication in theNIOSH Manual of Analytical Methods (NMAM). Both OC andEC are determined by NMAM 5040. An EC exposure markerwas recommended because EC is a more selective measure ofexposure.Aco
12、mprehensive review of the method and rationalefor selection of an EC marker are provided in a recent Chapterof NMAM (5).1.7 The thermal-optical instrument required for the analysisis manufactured by a private laboratory.3As with most instru-mentation, design improvements continue to be made. Differ-
13、ent laboratories may be using different instrument models.1.8 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 establish appro-priate safety and health practices and determine the applica-bil
14、ity of regulatory limitations prior to use. Specific precau-tionary statements are given in 7.1.5, 8.3, and 12.12.2.2. Referenced Documents2.1 ASTM Standards:4D 1356 Terminology Relating to Sampling and Analysis ofAtmospheres3. Terminology3.1 Definitions:1This test method is under the jurisdiction o
15、f ASTM Committee D22 onSampling and Analysis of Atmospheres and is the direct responsibility of Subcom-mittee D22.04 on Workplace Atmospheres.Current edition approved May 10, 2003. Published June 2003.2The boldface numbers in parentheses refer to references at the end of this testmethod.3The carbon
16、analyzer used in the development and performance evaluation ofthis test method was manufactured by Sunset Laboratory, 2017 19thAvenue, ForestGrove, Oregon 97116, which is the sole source of supply of the instrument knownto the committee at this time. If you are aware of alternative suppliers, please
17、provide this information to ASTM Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee which youmay attend.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
18、Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 For definitions of terms used in this practice, refer toTerminology D 1356.
19、3.3 limit of detection, LODA value for which exceedenceby measured mass indicates the presence of a substance atgiven false-positive rate: 3 3 estimated standard deviation ofestimated mass.3.4 Definitions of Terms Specific to This Standard:3.4.1 organic carbon (OC)Carbon volatilized in heliumwhile h
20、eating a quartz-fiber filter sample to 870C. Includescarbonates, if present, unless quantified separately. Also in-cludes char formed during pyrolysis of some materials.3.4.2 elemental carbon (EC)Excluding char, light-absorbing carbon that is not removed from a filter sampleheated to 870C in an iner
21、t atmosphere.3.4.3 total carbon (TC)Sum of organic and elementalcarbon.3.4.4 thermogramDigitized output signal of thermal-optical instrument. Shows detector and filter transmittancesignals at different temperatures in nonoxidizing and oxidizingatmospheres.3.5 Symbols and Abbreviations:3.5.1 DPMdiese
22、l particulate matter3.5.2 LOD (g/cm2)limit of detection: 3 3 sw3.5.3 sw(g/cm2)estimate of sw3.5.4 sw(g/cm2)standard deviation in collected massloading determination3.5.5 OC, EC, TC (g/cm2or g)organic, elemental, andtotal carbon3.5.6 RSDrelative standard deviation3.5.7 V (L)sampled volume3.5.8 Wb(g)f
23、ield blank filters EC mass reading3.5.9 WEC(g)active filters EC mass reading4. Summary of Test Method4.1 The thermal-optical analyzer has been described previ-ously (1-5). Design improvements have been made over time,but the operation principle remains unchanged. OC-EC quan-tification is accomplishe
24、d through temperature and atmospherecontrol. In addition, the analyzer is equipped with an opticalfeature that corrects for the char formed during the analysis ofsome materials. Optical correction is made with a pulsed diodelaser and photodetector that permit continuous monitoring ofthe filter trans
25、mittance.4.2 The main instrument components are illustrated in Fig.1. The instrument output, called a thermogram, is shown inFig. 2. For analysis, a known area (normally 1.5 cm2)ofthequartz-fiber filter sample is removed with a sharp metal punch.Quartz-fiber filters are required because temperatures
26、 in excessof 850C are employed. The portion is inserted into the sampleoven, and the oven is tightly sealed. The analysis proceeds ininert and oxidizing atmospheres. First, OC (and carbonate, ifpresent) is removed in helium as the temperature is stepped toa preset maximum (about 870C in NMAM 5040).
27、Evolvedcarbon is catalytically oxidized to CO2in a bed of granularMnO2. The CO2is then reduced to CH4in a Ni/firebrickmethanator, and CH4is quantified by a FID. Next, the sampleoven temperature is lowered, an oxygen-helium mix (2 %oxygen after dilution of the 10 % oxygen in helium supply) isintroduc
28、ed, and the temperature is increased to 900C (orhigher) to remove the residual carbon. At the end of eachanalysis, calibration is made through automatic injection of afixed volume of methane.4.3 Some samples contain components (for example, ciga-rette and wood smokes) that carbonize (convert to carb
29、on) orchar in helium during the first part of the analysis. Like ECinitially present in the sample, char strongly absorbs light,particularly in the red/infrared region. The char formed throughpyrolysis (thermal decomposition) of these components causesthe filter transmittance to decrease. Charring c
30、an begin at300C; the process may continue until the maximum tempera-ture is reached. After OC removal, an oxygen-helium mix isintroduced to effect combustion of residual carbon, whichincludes char and any EC originally present. As oxygen entersthe oven, light-absorbing carbon is oxidized and a concu
31、rrentincrease in filter transmittance occurs. The split (vertical lineprior to EC peak in Fig. 2) between OC and EC is assignedFIG. 1 Schematic of Thermal-Optical Instrument (V = valve) for Determination of Organic and Elemental Carbon in DPM and OtherCarbonaceous Aerosols.D6877032when the initial (
32、baseline) value of the filter transmittance isreached. All carbon removed before the OC-EC split isconsidered organic; that removed after the split is consideredelemental. If no char is formed, the split is assigned prior toremoval of EC. Ordinarily, the split is assigned in the oxidativemode of the
33、 analysis.4.4 Occasionally, original EC (as opposed to char) is lostwith the fourth temperature step in helium. Loss of EC inhelium is uncommon, but sometimes occurs, possibly due tooxidants in the sample. The OC-EC split is automaticallyassigned earlier (in helium) in these cases (5).4.5 OC and EC
34、results are reported in units g per cm2offilter deposit. The total OC and EC on the filter are calculatedby multiplying the reported values by the deposit area (slightlyless than the filter area). A homogeneous deposit is assumed.The TC in the sample is the sum of OC and EC. If carbonateis present,
35、the carbon in it is quantified as OC unless correctionis made. Additional details about carbonates are given in afollowing section.5. Significance and Use5.1 The test method supports proposed, occupational expo-sure standards (6, 7) for DPM. In the United States alone, overa million workers are occu
36、pationally exposed (8). An exposurestandard for mines is especially important because minersexposures are often quite high. NIOSH (8), the InternationalAgency for Research on Cancer (9) (IARC), the World HealthOrganization (10) (WHO), the California Environmental Pro-tection Agency (11), the U.S. En
37、vironmental ProtectionAgency (12) (EPA), and the National Toxicology Program (13)have reviewed the animal and human evidence. All haveclassified diesel exhaust as a probable human carcinogen orsimilar designation.5.2 The test method provides a measure of occupationalexposure to DPM. Previous studies
38、 have produced equivocalresults because exposure data are lacking. Given the economicand public health impact of epidemiological studies, accuraterisk assessment is critical. An ongoing NIOSH/NCI study ofminers exposed to diesel exhaust should provide a morequantitative estimate of the lung cancer r
39、isk. The test methodwas used for exposure monitoring. Since publication (in 1996)as NMAM 5040, the method has been routinely used foroccupational monitoring (5).5.3 The test method supports a proposed EPA air standardfor fine particulate carbon. Recent studies indicate a positiveassociation between
40、airborne levels of fine particles andrespiratory illness and mortality (14-22). The test method andothers have been used for EPA air monitoring networks and airpollution studies. Because different methods produce differentresults, method standardization is essential for regulatorycompliance determin
41、ations and valid comparisons of interlabo-ratory data.5.4 The test method is being applied for emission-controltesting.6. Interferences6.1 EC is a more selective marker of occupational exposurethan other measures of DPM (for example, particulate mass,NOTE 1PC is pyrolytically generated carbon (char)
42、. Final peak is methane calibration peak. Carbon sources: pulverized beet pulp, rock dust(carbonate), and diesel particulate.NOTE 2In the comparative test reported by Birch (28), participants used different maximum temperatures in helium (5). The actual maximum rangedfrom about 850-900C. NMAM 5040 s
43、pecifies 870C, which is near the middle of the range.FIG. 2 Thermogram for Filter Sample Containing OC, Carbonate (CC), and EC.D6877033total carbon). As defined by the test method, EC is the carbondetermined during the second stage of the analysis (afterpyrolysis correction). If the sample contains
44、no pyrolyzablematerial, all carbon evolved during this stage is consideredelemental. Inorganic dusts, carbonates, and wood and cigarettesmokes ordinarily do not interfere in the EC determination(2-5). OC can be contributed by smokes, fumes and othersources.6.2 If high levels of other dusts are prese
45、nt, a size classifier(for example, impactor, or cyclone, or both) should be used. Ifthe dust is carbonaceous, a size classifier provides a moreselective measure of the diesel-source OC. It also provides abetter measure of the diesel-source EC if the dust contains EC(for example, carbon black, coal),
46、 which is less common. Afinely ground sample of the bulk material can be analyzed todetermine whether a dust poses potential interference. Depend-ing on the dust concentration, size distribution, and targetanalyte (EC or TC), an impactor/cyclone may required. Addi-tional details can be found elsewhe
47、re (5). Some OC interfer-ences cannot be excluded on the basis of size (for example,cigarette smoke and other combustion aerosols, condensationaerosol, fumes).6.3 In metal and nonmetal mines, the Mine Safety andHealth Administration (MSHA) recommends use of a special-ized impactor (with cyclone) to
48、minimize collection of carbon-ates and other carbonaceous dusts (7).6.4 For measurement of diesel-source EC in coal mines, animpactor with sub-micrometer cutpoint (7, 23, 24) must beused to minimize collection of coal dust. Only low levels of ECwere found in non-dieselized coal mines when an impacto
49、rwith a sub-micrometer cutpoint was used (25).6.5 Environmental samples usually contain little (if any)carbonate. Levels in some occupational settings are quite high.Depending on the carbonate type, a carbonate-subtracted valuefor OC (and TC) can be obtained through acidification of thesample or separate integration of the carbonate peak (see12.12).7. Apparatus7.1 The main components of the thermal-optical analyzerused in the test method are illustrated in Fig. 1. The principalcomponents are:7.1.1 Sample oventemperature programmable.7.1.2 Oxidiz
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