1、Designation: D6877 131Standard Test Method forMonitoring Diesel Particulate Exhaust in the Workplace1This standard is issued under the fixed designation D6877; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial changes were submitted after publication in October 2013.1. Scope1.1 This test method covers determination of organic andeleme
3、ntal carbon (OC and EC) in the particulate fraction ofdiesel engine exhaust, hereafter referred to as diesel particulatematter (DPM). Samples of workplace atmospheres are col-lected on quartz-fiber filters. The method also is suitable forother types of carbonaceous aerosols and has been widelyapplie
4、d to environmental monitoring. It is not appropriate forsampling volatile or semi-volatile components. These compo-nents require sorbents for efficient collection.NOTE 1Sample collection and handling procedures for environmentalsamples differ from occupational samples. This standard addresses occu-p
5、ational monitoring of DPM in workplaces where diesel-powered equip-ment is used.1.2 The method is based on a thermal-optical technique (1,2)2. Speciation of OC and EC is achieved through temperatureand atmosphere control, and an optical feature that corrects forsample charring (carbonization).1.3 A
6、portion of a 37-mm, quartz-fiber filter sample isanalyzed. Results for the portion are used to calculate the totalmass of OC and EC on the filter. The portion must berepresentative of the entire filter deposit. If the deposit isuneven, two or more representative portions should be ana-lyzed for an a
7、verage. Alternatively, the entire filter can beanalyzed, in multiple portions, to determine the total mass.Open-faced cassettes give even deposits but may not bepractical. At 2 L/min, closed-face cassettes generally giveresults equivalent to open-face cassettes if other dusts areabsent. Higher flow
8、rates may be employed, but closed-facedcassettes operated at higher flow rates (for example, 5 L/min)sometimes have uneven deposits due to particle impaction atthe center of the filter. Other samplers may be required,depending on the sampling environment (2-5).1.4 The calculated limit of detection (
9、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 sucrose standard solution applied to filterportions cleaned immediately before analysis. LODs based onmedia blanks stored after cleaning are usually hi
10、gher. LODsbased on a set of media blanks analyzed over a six monthperiod at a commercial laboratory were OC = 1.2 g/cm2, EC= 0.4 g/cm2, and TC = 1.3 g/cm2, where TC refers to totalcarbon (TC = OC + EC). In practice, the LOD estimateprovided by a laboratory is based on results for a set of mediablank
11、s submitted with the samples. To reduce blank variability(due to lack of loading), a manual OC-EC split is assigned atthe time when oxygen is introduced. With manual splits, theSD for media blanks is typically about 0.02-0.03 g EC/cm2,giving LODs (3 SD blank) from about 0.06-0.09 g EC/cm2.The corres
12、ponding air concentration depends on the depositarea (filter size) and air volume.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 com
13、ponents.The analysismethod is 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
14、by the National Institute forOccupational Safety and Health (NIOSH). Method updates (3,4) have been published since its initial (1996) publication in theNIOSH Manual ofAnalytical Methods (NMAM). Both OC andEC are determined by NMAM 5040. An EC exposure marker(for DPM) was recommended because EC is a
15、 more selectivemeasure of exposure. A comprehensive review of the methodand rationale for selection of an EC marker are provided in aChapter of NMAM (5).1This test method is under the jurisdiction of ASTM Committee D22 on AirQualityand is the direct responsibility of Subcommittee D22.04 on Workplace
16、 AirQuality.Current edition approved Oct. 1, 2013. Published October 2013. Originallyapproved in 2003. Last previous edition approved in 2008 as D6877 03 (2008).DOI: 10.1520/D6877-13.2The boldface numbers in parentheses refer to references at the end of this testmethod.Copyright ASTM International,
17、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.7 The thermal-optical instrument required for the analysisis manufactured by a private laboratory.3As with mostinstrumentation, design improvements continue to be made.Different laboratories may be using different
18、instrument mod-els.1.8 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.9 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 standar
19、d to establish appro-priate safety and health practices and determine the applica-bility 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:4D1356 Terminology Relating to Sampling and Analysis ofAt
20、mospheres3. Terminology3.1 For definitions of terms used in this test method, refer toTerminology D1356.3.2 Definitions:3.2.1 limit of detection, LODA value for which ex-ceedence by measured mass indicates the presence of asubstance at given false-positive rate: 3 estimated standarddeviation of esti
21、mated mass of a blank.3.3 Definitions of Terms Specific to This Standard:3.3.1 organic carbon (OC)Carbon volatilized in heliumwhile heating a quartz-fiber filter sample to 870C. Includescarbonates, if present, unless quantified separately. Also in-cludes char formed during pyrolysis of some material
22、s.3.3.2 elemental carbon (EC)Excluding char, light-absorbing carbon that is not removed from a filter sampleheated to 870C in an inert atmosphere.3.3.3 total carbon (TC)Sum of organic and elementalcarbon.3.3.4 thermogramDigitized output signal of thermal-optical instrument. Shows detector and filter
23、 transmittancesignals at different temperatures in nonoxidizing and oxidizingatmospheres.3.4 Symbols and Abbreviations:3.4.1 DPMdiesel particulate matter3.4.2 LOD (g/cm2)limit of detection:3sw3.4.3 sw(g/cm2)estimate of w3.4.4 w(g/cm2)standard deviation in collected massloading determination3.4.5 OC,
24、 EC, TC (g/cm2or g)organic, elemental, andtotal carbon3.4.6 RSDrelative standard deviation3.4.7 V (L)sampled volume3.4.8 Wb(g)field blank filters EC mass reading3.4.9 WEC(g)active filters EC mass reading4. Summary of Test Method4.1 The thermal-optical analyzer has been described previ-ously (1-5). D
25、esign improvements have been made over time,but the operation principle remains unchanged. OC-EC quan-tification is accomplished through temperature and atmospherecontrol. In addition, the analyzer is equipped with an opticalfeature that corrects for the char formed during the analysis ofsome materi
26、als. Optical correction is made with a pulsed diodelaser and photodetector that permit continuous monitoring ofthe filter transmittance/reflectance.4.2 The main instrument components (transmittance instru-ment) are illustrated in Fig. 1. The instrument output, called athermogram, is shown in Fig. 2.
27、 For analysis, a known area(normally 1.5 cm2) of the quartz-fiber filter sample is removedwith a sharp metal punch. Quartz-fiber filters are requiredbecause temperatures in excess of 850C are employed. Theportion is inserted into the sample oven, and the oven is tightlysealed. The analysis proceeds
28、in inert and oxidizing atmo-spheres. First, OC (and carbonate, if present) is removed inhelium as the temperature is stepped to a preset maximum(usually 850C in NMAM 5040; see 4.4). Evolved carbon iscatalytically oxidized to CO2in a bed of granular MnO2. TheCO2is then reduced to CH4in a Ni/firebrick
29、 methanator, andCH4is quantified by a FID. Next, the sample oven temperatureis lowered, an oxygen-helium mix (2 % oxygen after dilutionof the 10 % oxygen in helium supply) is introduced, and thetemperature is increased to 900C (or higher) to remove(oxidize) the remaining carbon, some or all of which
30、 is EC,depending on whether char is formed during the first part of theanalysis (a char correction is made if so). 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) tha
31、t carbonize (convert to carbon) toform char in helium during the first part of the analysis. LikeEC typical of fine particle pollution, char strongly absorbslight, particularly in the red/infrared region. The char formedthrough pyrolysis (thermal decomposition) of these compo-nents causes the filter
32、 transmittance/reflectance to decrease.Charring can begin at 300C; the process may continue untilthe maximum temperature is reached. After OC removal, anoxygen-helium mix is introduced to effect combustion ofresidual carbon, which includes char and any EC originallypresent. As oxygen enters the oven
33、, light-absorbing carbon isoxidized and a concurrent increase in filter transmittanceoccurs. The split (vertical line prior to EC peak in Fig. 2)3The carbon analyzer used in the development and performance evaluation ofthis test method was manufactured by Sunset Laboratory, 2017 19thAvenue, ForestGr
34、ove, 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, pleaseprovide this information to ASTM Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical commit
35、tee which youmay attend.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, refer to the standards Document Summary page onthe ASTM website.D6877 1312between OC and EC is assign
36、ed when the initial (baseline)value of the filter transmittance is reached.All carbon removedbefore the OC-EC split is considered organic; that removedafter the split is considered elemental. If no char is formed, thesplit is assigned prior to removal of EC. Ordinarily, the split isassigned in the o
37、xidative mode of the analysis.4.4 Occasionally, the sample EC (along with any charformed) is lost during the fourth temperature step in helium.Loss of EC in helium is uncommon but sometimes occurs,possibly due to oxidants in the sample. In cases when loss is toan extent where the filter transmittanc
38、e reaches/exceeds itsinitial (baseline) value during the first part of the analysis (inhelium), the OC-EC split is automatically assigned earlier, inhelium mode (5). A lower preset maximum (for example,650C) can be used to reduce EC/char loss in helium so that thesplit occurs during the oxidative mo
39、de (5).4.5 OC and EC results are reported in units g per cm2offilter deposit. The total OC and EC on the filter are calculatedFIG. 1 Schematic of Thermal-Optical Instrument (V = valve) for Determination of Organic and Elemental Carbon in DPM and Other Car-bonaceous Aerosols.NOTE 1PC is pyrolytically
40、 generated carbon (char). Final peak is methane calibration peak. Carbon sources: pulverized beet pulp, rock dust(carbonate), and diesel particulate matter.NOTE 2In the comparative test reported by Birch (6), participants used different maximum temperatures in helium (5). The actual maximum rangedfr
41、om about 850-900C. NMAM 5040 specifies 870C, which is near the middle of this range.FIG. 2 Thermogram for Filter Sample Containing OC, Carbonate (CC), and EC.D6877 1313by multiplying the reported values by the deposit area (slightlyless than the filter area). A homogeneous deposit is assumed.The TC
42、in the sample is the sum of OC and EC. If carbonateis present, 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 previously proposed occupa-tional exposure standards (
43、7, 8) for DPM.ADPM exposurelimit has since been promulgated for metal and nonmetalmines, but there currently are no limits for general occupa-tional settings (a proposed limit (7) was withdrawn from theACGIH Notice of Intended Changes (NIC) list in 2003). In theUnited States alone, over a million wo
44、rkers are occupationallyexposed (9). An exposure standard for mines is especiallyimportant because miners exposures are often quite high.NIOSH (9), the International Agency for Research on Cancer(10) (IARC), the World Health Organization (11) (WHO), theCalifornia Environmental Protection Agency (12)
45、, the U.S.Environmental ProtectionAgency (13) (EPA), and the NationalToxicology Program (14) reviewed the animal and humanevidence on DPM and all classified diesel exhaust as aprobable human carcinogen or similar designation. In 2012, theWHO reclassified diesel exhaust as carcinogenic to humans(Grou
46、p 1) (15). In addition, in a study of miners, the NationalCancer Institute (NCI) and NIOSH reported increased risk ofdeath from lung cancer in exposed workers (16 and 17).5.2 The test method provides a measure of occupationalexposure to DPM. Given the economic and public healthimpact of epidemiologi
47、cal studies, accurate risk assessment iscritical. The NIOSH/NCI study of miners exposed to dieselexhaust provides quantitative estimates of lung cancer risk (16and 17). The test method was used for exposure monitoring.Since publication (in 1996) as NMAM 5040, the method hasbeen routinely used for oc
48、cupational monitoring (5).5.3 Studies indicate a positive association between airbornelevels of fine particles and respiratory illness and mortality(18-26). The test method and others have been used for EPAairmonitoring networks and air pollution studies. Because differ-ent methods produce different
49、 results, method standardizationis essential for regulatory compliance determinations and validcomparisons of interlaboratory 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,total carbon). As defined by the test method, EC is the carbondetermined during the second stage of the analysis (afterpyrolysis correction). If the sample contains no pyrolyzablematerial, all carbon evo
