1、Designation: D7948 14Standard Test Method forMeasurement of Respirable Crystalline Silica in WorkplaceAir by Infrared Spectrometry1This standard is issued under the fixed designation D7948; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, 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.1. Scope1.1 This standard specifies a test method for collection andanalysis of samples of airborne particulate
3、 matter for measure-ment of respirable crystalline silica by infrared (IR) spectrom-etry.1.2 This test method is applicable to the analysis of crystal-line silica (the polymorphs quartz, cristobalite and tridymite)over a working range of 0.025 to 0.4 mg/m3for a 400 L airsample or 0.02 to 0.25 mg/m3f
4、or a 1000 L air sample,depending on the analytical method.1.3 The methodology is applicable to personal sampling ofthe respirable fraction of airborne particles and to static (area)sampling.1.4 This test method describes three different procedures forsample preparation and infrared analysis of airbo
5、rne crystallinesilica samples, which are delineated in Annex A1 Annex A3,respectively: (1) a potassium bromide (KBr) disc IR measure-ment method, (2) indirect IR analysis after redeposition onto afilter used for measurement, and (3) direct on-filter IR analysis.1.5 The values stated in SI units are
6、to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 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 a
7、nd determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD4532 Test Method for Respirable Dust in Workplace At-mospheres Using Cyclone SamplersD4840 Guide for Sample Chain-of-Cus
8、tody ProceduresD6061 Practice for Evaluating the Performance of Respi-rable Aerosol SamplersE1370 Guide for Air Sampling Strategies for Worker andWorkplace Protection2.2 ISO Standards:3ISO 7708 Air quality Particle size fraction definitions forhealth-related samplingISO 3534-1 Statistics Vocabulary
9、and symbols Part 1:Probability and general statistical terms in metrologyISO 6879 Air quality Performance characteristics andrelated concepts for air quality measuring methodsISO 13137 Workplace air Pumps for personal samplingof chemical and biological agents Requirements andtest methodsISO 15202-1
10、Workplace air Determination of metals andmetalloids in airborne particulate matter by inductivelycoupled plasma atomic emission spectrometry Part 1:SamplingISO 15767 Workplace atmospheres Controlling and char-acterizing errors in weighing collected aerosolsISO 24095 Workplace air Guidance for the me
11、asurementof respirable crystalline silica3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminology D1356.3.2 Definitions of General Terms Specific to This Standard:3.2.1 respirable crystalline silica (RCS), ninhaled par-ticles of crystalline silica th
12、at penetrate into the unciliatedairways. ISO 240953.2.2 chemical agent, nany chemical element orcompound, on its own or admixed as it occurs in the naturalstate or as produced by any work activity, whether or notproduced intentionally and whether or not commercially avail-able.1This test method is u
13、nder the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.04 on Workplace AirQuality.Current edition approved Oct. 15, 2014. Published February 2015. DOI:10.1520/D7948-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcont
14、act ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright
15、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.3 breathing zone, n(general definition) space aroundthe workers face from where he or she takes his or her breath.EN 1540 (1)4(technical definition) hemisphere (generally accepted to be0.3 m i
16、n radius) extending in front of the human face, centredon the midpoint of a line joining the ears; the base of thehemisphere is a plane through this line, the top of the head andthe larynx. ISO 15202-13.2.4 exposure (by inhalation), nsituation in which achemical agent is present in air which is inha
17、led by a person.EN 1540 (1)3.2.5 limit value, nreference figure for concentration of achemical agent in air. EN 1540 (1)3.2.6 measurement procedure, nset of operations, de-scribed specifically, for the sampling and analysis of chemicalagents in air. EN 1540 (1)3.2.6.1 DiscussionA measurement procedu
18、re usually in-cludes preparation for sampling, sampling, transportation andstorage, preparation of samples for analysis and analysis.3.2.7 reference period, nspecified period of time forwhich the (occupational exposure) limit value of a chemicalagent applies. EN 1540 (1)3.2.8 time-weighted average (
19、TWA) concentration,nconcentration of a chemical agent in the atmosphere,averaged over the reference period. E1370; ISO 15202-13.2.9 workplace, ndefined area or areas in which the workactivities are carried out. EN 1540 (1)3.3 Definitions of Particle Size Fraction Terms Specific toThis Standard:3.3.1
20、 respirable convention, ntarget specification for sam-pling instruments when the respirable fraction is of interest.ISO 77083.3.2 respirable fraction, n mass fraction of inhaledparticles penetrating to the unciliated airways. ISO 77083.4 Definitions of Sampling Terms Specific to This Standard:3.4.1
21、operating time, nperiod during which a samplingpump can be operated at specified flow rate and back pressurewithout recharging or replacing the battery. ISO 131373.4.2 personal sampler, nsampling device, attached to aperson, which collects airborne particles in the breathing zone.3.4.3 personal samp
22、ling, nprocess of sample collectioncarried out using a personal sampler.3.4.4 (air) sampler, ndevice for collecting chemicalagents from the surrounding air.3.4.4.1 DiscussionAir samplers are generally designed fora particular purpose, for example, for sampling airborneparticles.3.4.5 sampling instru
23、ment, ndevice for collecting airborneparticles, including the sampler, sampling pump and samplingmedium such as a filter.3.4.6 sampling train, napparatus for collecting airborneparticles including sampling pump, connecting tubing, respi-rable size selector, and collection medium (for example, afilte
24、r).3.4.7 static (area) sampler, nsampler, not attached to aperson, which collects airborne particles at a particularlocation. EN 1540 (1)3.4.8 static (area) sampling, nprocess of (air) samplingcarried out using a static sampler. EN 1540 (1)3.5 Definitions of Analytical Terms Specific to This Stan-da
25、rd:3.5.1 sample preparation, n operations carried out on asample, after transportation and storage, to prepare it foranalysis, including transformation of the sample into a mea-surable state. ISO 240953.5.2 limit of detection (LOD), nlowest reliable mass ofcrystalline silica that is detected taking
26、into consideration thematrix effects in the sample. ISO 240953.5.3 limit of quantification (LOQ), nlowest reliable massof crystalline silica that is quantifiable taking into considerationthe matrix effects in the sample. ISO 240953.6 Definitions of Statistical Terms Specific to This Stan-dard:3.6.1
27、accuracy, ncloseness of agreement between a testresult and the accepted reference value. ISO 3534-13.6.2 analytical recovery, nratio of the mass of analytemeasured in a sample to the known mass of analyte in thatsample. EN 1540 (1)3.6.3 bias, nconsistent deviation of the results of a mea-surement pr
28、ocess from the true value of the air qualitycharacteristic itself. ISO 68793.6.3.1 DiscussionBias is the total systematic error ascontrasted to random error. There may be one or moresystematic error components contributing to the bias.3.6.4 precision, nthe closeness of agreement of resultsobtained b
29、y applying the method several times under pre-scribed condition. ISO 68793.6.5 uncertainty (of measurement), nparameter associ-ated with the result of a measurement that characterizes thedispersion of the values that could reasonably be attributed tothe measurand. ISO 3534-14. Summary of Test Method
30、4.1 Airborne particles are collected by drawing a measuredvolume of air through a filter mounted in a sampler designed tocollect the respirable fraction of airborne particles. Aftersampling for a specified reference period at a given airsampling flow rate, the sampling substrate (normally a filter)a
31、nd collected sample are treated to prepare the collectedcrystalline silica particulate matter for subsequent measure-ment by infrared (IR) spectrometry. Characteristic IR peaks forcrystalline silica are measured and used to determine the massof crystalline silica in the collected air sample. Three d
32、ifferentprocedures for sample preparation and infrared analysis ofairborne crystalline silica samples are described: (1) a potas-sium bromide (KBr) disc IR measurement method (after initial4The boldface numbers in parentheses refer to a list of references at the end ofthis standard.D7948 142filter c
33、ollection and subsequent sample treatment); (2) indirectIR analysis after redeposition onto a filter used for measure-ment; and (3) direct on-filter IR analysis. The measurementresults can be compared to applicable occupational limit values(OELs) for crystalline silica in respirable airborne particu
34、latesamples.5. Significance and Use5.1 Respirable crystalline silica is a hazard to the health ofworkers in many industries who are at risk through exposure byinhalation. Industrial hygienists and other public health profes-sionals need to determine the effectiveness of measures takento control work
35、ers exposure, and this is generally achieved bytaking workplace air measurements. This standard has beenpublished in order to make available a method for making validexposure measurements for crystalline silica exposures inindustry. It will be of benefit to: agencies concerned with healthand safety
36、at work; industrial hygienists and other public healthprofessionals; analytical laboratories; industrial users of silica-containing products and their workers, etc.5.2 This standard specifies a generic sampling and analyti-cal method for measurement of the mass concentration ofrespirable crystalline
37、 silica in workplace air using infrared (IR)spectrometric methods. Several different types of samplingapparatus are used to collect respirable dust, according to theoccupational hygiene sampling convention. This standard isdesigned to accommodate a variety of appropriate samplersand sampling materia
38、ls that are commercially available.6. Interferences6.1 The applicability and performance of the infrared tech-nique(s) used to measure respirable crystalline silica (RCS) is(are) dependent on the ability to address matrix and mineralinterferences (ISO 24095). It is necessary to consider thematrix an
39、d mineral interferences potentially present in airbornesamples, and to take action to minimize these interferences inIR analysis of RCS. Numerous minerals that could be presentalong with crystalline silica in airborne respirable samplesabsorb infrared radiation in the spectral region of the quartzab
40、sorbance bands at 799 cm-1and 780 cm-1, giving rise topositive interference (2 and 3). Some of the more frequentlyencountered of these minerals, along with their characteristicIR frequencies in the range 4501000 cm-1, are presented inTable 1 (2-4). Examples of commonly encountered mineralsthat can i
41、nterfere with IR analysis include kaolinite, a constitu-ent of clays; muscovite, which is present in micas; and albite,anorthite and orthoclase, which are feldspars.6.2 Quartz is a common component of soil, rocks, sand,mortar, cement, fluxes, abrasives, glass, porcelain, paints, andbrick. Cristobali
42、te is less common and may be a constituent ofvolcanic rocks and soils; it can be formed in high temperaturework such as foundry processes, calcining diatomaceous earth,brick fabrication, ceramic manufacturing and silicon carbideproduction. Tridymite, which is rarely encountered inworkplaces, is pres
43、ent in some volcanic rocks and soils.6.3 If necessary, quartz and cristobalite can be determined inthe presence of other mineral interferences absorbing at 800cm-1by measurement of the identifying bands at 694 cm-1forquartz and 623 cm-1for cristobalite (56). Cristobalite andtridymite absorb at 800 c
44、m-1, although they are rarelyencountered in practice (tridymite particularly). Kaolinite,which is a common component of coal, can interfere if it ispresent in appreciable quantities. Calcite, if present at amountsgreater than 20 % of total dust loadings, can interfere byreacting with quartz during s
45、ample preparation. (Calcite is aprevalent constituent of limestone.) Amorphous silica mayinterfere if present in large amounts; its interference can beminimized by measuring alternative but less sensitive bands at694 cm-1for quartz and 623 cm-1for cristobalite.6.4 Besides minerals, matrix interferen
46、ces from other mate-rials can affect IR analysis. For example, carbonaceous mate-rials are ubiquitous matrix interferants in, for example, coalmines, and iron oxide is a common matrix interferant in, forexample, foundries. Numerous background matrix and mineralinterferences may be present in airborn
47、e dust emanating fromconstruction activities. Various techniques are used in samplepreparation and IR measurement in efforts to account for andminimize matrix interferences.6.5 Standard mixtures of potentially interfering mineralscan be prepared using the same sample preparation techniquesas for sta
48、ndard crystalline silica samples, and the effect ofinterference on the IR spectrum can then be assessed andcorrected for mathematically. These techniques, which are usedto minimize background and mineral interferences to IRmeasurement, are described in Annex A1 Annex A3. Gen-erally sample ashing tec
49、hniques (described in Annex A1 andAnnex A2) are more effective at addressing interferences andmatrix effects that might not be adequately accounted for byuse of the direct on-filter method (Annex A3).6.6 Knowledge of and training in geochemistry and miner-alogy is strongly recommended for users of this standard.Although many analytical chemists are familiar with IRspectroscopy (like as applied to organic analysis), mineralogi-cal samples, such as samples containing airborne respirablecrystalline silica, require additional kno
