1、Designation: D4185 17Standard Test Method forMeasurement of Metals in Workplace Atmospheres byFlame Atomic Absorption Spectrophotometry1This standard is issued under the fixed designation D4185; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f revision, 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 test method covers the collection, dissolution, anddetermination of trace metals in workp
3、lace atmospheres, byflame atomic absorption spectrophotometry (FAAS).1.2 The sensitivity, detection limit, and optimum workingconcentration for 23 metals are given in Table 1.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1
4、.4 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-bility of regulatory limitations prior to use. (Specific safet
5、yprecautionary statements are given in Section 9.)1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by
6、 the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD1357 Practice for Planning the Sampling of the AmbientAtmosphereD3195 Practice fo
7、r Rotameter CalibrationD5337 Practice for Flow Rate Adjustment of Personal Sam-pling PumpsD7035 Test Method for Determination of Metals and Met-alloids in Airborne Particulate Matter by InductivelyCoupled Plasma Atomic Emission Spectrometry (ICP-AES)3. Terminology3.1 DefinitionsFor definitions of te
8、rms used in this testmethod, refer to Terminology D1356.3.2 Definitions of Terms Specific to This Standard:3.2.1 blank signalthat signal which results from all addedreagents and a clean membrane filter prepared and analyzedexactly in the same way as the samples.3.2.2 instrumental detection limitthat
9、 concentration of agiven element which produces a signal three times the standarddeviation of the reagent blank signal.3.2.3 working range for an analytical precision better than3%the range of sample concentrations that will absorb 10 to70 % of the incident radiation (0.05 to 0.52 absorbance units).
10、NOTE 1Values for instrumental detection limit may vary frominstrument to instrument.4. Summary of Test Method4.1 Workplace air samples are collected on membrane filtersand treated with nitric acid to destroy the organic matrix and todissolve the metals present. The analysis is subsequently madeby fl
11、ame atomic absorption spectrophotometry (FAAS).4.2 Samples and standards are aspirated the flame of anabsorption spectrophotometer. A hollow cathode or electrode-less discharge lamp for the metal being determined provides asource of characteristic radiation energy for that particularmetal. The absor
12、ption of this characteristic energy by the atomsof interest in the flame is related to the concentration of themetal in the aspirated sample. The flame and operatingconditions for each element are listed in Table 2.5. Significance and Use5.1 The health of workers in many industries is at riskthrough
13、 exposure by inhalation to toxic metals. Industrialhygienists and other public health professionals need to deter-mine the effectiveness of measures taken to control workersexposures, and this is generally achieved by making workplace1This test method is under the jurisdiction of ASTM Committee D22
14、on AirQuality and is the direct responsibility of Subcommittee D22.04 on Workplace AirQuality.Current edition approved March 1, 2017. Published March 2017. Originallyapproved in 1990. Last previous edition approved in 2011 as D4185 06 (2011).DOI: 10.1520/D4185-17.2For referenced ASTM standards, visi
15、t 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
16、9. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical B
17、arriers to Trade (TBT) Committee.1air measurements. Exposure to some metal-containing particleshas been demonstrated to cause dermatitis, skin ulcers, eyeproblems, chemical pneumonitis, and other physical disorders(1).35.2 FAAS is capable of quantitatively determining mostmetals in air samples at th
18、e levels required by federal, state,and local occupational health and air pollution regulations. Theanalysis results can be used for the assessment of workplaceexposures to metals in workplace air.6. Interferences6.1 In FAAS the occurrence of interferences is less commonthan in many other analytical
19、 techniques. Interferences canoccur, however, and when encountered are corrected for asindicated in the following sections. The known interferencesand correction methods for each metal are indicated in Table 2.The methods of standard additions and background monitoringand correction (2, 4, 8, 9) are
20、 used to identify the presence ofan interference. Insofar as possible, the matrix of sample andstandard are matched to minimize the possible interference.6.2 Background or nonspecific absorption can occur fromparticles produced in the flame which can scatter light andproduce an apparent absorption s
21、ignal. Light scattering may beencountered when solutions of high salt content are beinganalyzed. They are most severe when measurements are madeat shorter wavelengths (for example, below about 250 nm).Background absorption may also occur as the result of theformation of various molecular species whi
22、ch can absorb light.The background absorption can be accounted for by the use ofbackground correction techniques (8).6.3 Spectral interferences are those interferences whichresult from an atom different from the one being measured thatabsorbs a portion of the radiation. Such interferences areextreme
23、ly rare in FAAS. In some cases multielement hollowcathode lamps may cause a spectral interference by havingclosely adjacent emission lines from two different elements. Ingeneral, the use of multielement hollow cathode lamps isdiscouraged.6.4 Ionization interference occurs when easily ionized at-oms
24、are being measured. The degree to which such atoms areionized is dependent upon the atomic concentration and thepresence of other easily ionized atoms. This interference can becontrolled by the addition of a high concentration of anothereasily ionized element which will buffer the electron concen-tr
25、ation in the flame.6.5 Chemical interferences occur in FAAS when speciespresent in the sample cause variations in the degree to whichatoms are formed in the flame, or when different valence statesof a single element have different absorption characteristics.Such interferences may be controlled by ad
26、justing the samplematrix or by the method of standard additions (9).Also, the useof lanthanum as a releasing element minimizes the interferencefrom the formation of nonvolatile compounds in the flame.Lanthanum forms nonvolatile compounds preferentially withthe interferent so that the analyte remains
27、 free.6.6 Physical interferences may result if the physical prop-erties of the samples vary significantly. Changes in viscosityand surface tension can affect the sample aspiration rate and3Boldface numbers in parentheses refer to the list of references appended tothese methods.TABLE 1 FAAS Instrumen
28、tal Detection Limits and Optimum Working Concentration for 23 MetalsElementDetection Limit, g/mL(approximately three timesstandard deviation of blank)AOptimum Linear RangeUpper Limit,g/mLTLV, mg/m3(elements, compound classes, and oxides)BAg 0.001 5 0.1 (metal) 0.01 (soluble compounds as Ag)Al 0.04 5
29、0 2.0 (soluble salts and alkyls not otherwise classified) 10 (metal dust and oxide)5 (pyro powder and welding fume)Ba 0.01 10 0.5 (soluble compounds)Bi 0.03 10 No Limit expressed for this elementCa 0.002 1 2 (oxide as CaO)Cd 0.0008 1 0.01 (elemental and compoundstotal dust)0.002 (elemental compounds
30、respirable fraction)Co 0.009 5 0.02 (elemental and inorganic) 0.1 (carbonyl and hydrocarbonyl)Cr 0.003 5 0.5 (metal and Cr III compounds) 0.05 (water soluble Cr VI compounds)0.01 (insoluble Cr VI compounds)Cu 0.002 5 0.2 (fume) 1 (dust and mists as Cu)Fe 0.005 5 5 (iron oxide fume) 5 (soluble salts
31、as Fe)In 0.03 50 0.1 (metal and compounds)K 0.003 1 No Limit expressed for this elementLi 0.0008 1 No Limit expressed for this elementMg 0.0002 0.5 10 (as MgO fume)Mn 0.002 5 0.2 (elemental and inorganic compounds)Na 0.0003 0.5 No Limit expressed for this elementNi 0.006 5 0.05 (elemental, soluble a
32、nd insoluble compounds)Pb 0.02 10 0.15 (inorganic compounds, fume, dust)Rb 0.003 5 No Limit expressed for this elementSr 0.003 5 No Limit expressed for this elementTl 0.02 50 0.1 (soluble compounds)V 0.06 100 0.05 (pentoxide, respirable dust or fume, as V2O5)Zn 0.002 1 10 (oxide dust as ZnO) 5 (oxid
33、e fume as ZnO)AThese detection limits represent ideal laboratory conditions; variability due to sampling, digestion, reagents, and sample handling has not been taken into account.BThreshold Limit Values of Airborne Contaminants and Physical Agents adopted by ACGIH for 19941995. Values are elemental
34、concentrations except as noted.D4185 172thus cause erroneous results. Sample dilution or the method ofstandard additions, or both, are used to correct such interfer-ences. High concentrations of silica in the sample can causeaspiration problems. No matter what elements are beingdetermined, if large
35、amounts of silica are extracted from thesamples, they shall be allowed to stand for several hours andcentrifuged or filtered to remove the silica.6.7 This procedure describes a generalized method forsample preparation, which is applicable to the majority ofsamples. There are some relatively rare che
36、mical forms of afew of the elements listed in Table 1 that will not be dissolvedby this procedure. If such chemical forms are suspected, resultsobtained using this procedure shall be compared with thoseobtained using an appropriately altered dissolution procedure.Alternatively, the results may be co
37、mpared with values ob-tained using a technique that does not require dissolving thesample (for example, X-ray fluorescence or neutron activationanalysis).7. Apparatus7.1 Sampling Apparatus:7.1.1 Cellulose Ester or Cellulose Nitrate MembraneFilters, with a pore size of 0.8 m mounted in a 25-mm or37-m
38、m diameter two- or three-piece filter holder.NOTE 2Appropriate workplace air samplers are described in TestMethod D7035. The background metal content of the filters should beminimal (see Annex A1 of Test Method D7035).7.1.2 Portable, Battery-Operated Personal SamplingPumps, equipped with a flow-moni
39、toring device (rotameter,critical orifice) or a constant-flow device and capable ofdrawing 15 L/min of air through the 0.8-m membrane filterfor a period of 8 h.7.2 Analytical Apparatus:7.2.1 Flame Atomic Absorption Spectrophotometer,equipped with air/acetylene and nitrous oxide/acetylene burnerheads
40、.7.2.2 Hollow Cathode or Electrodeless Discharge Lamp, foreach element to be determined.7.2.3 Deuterium Continuum Lamp.7.2.4 Compressed AirAppropriate pressure reducing regu-lator with base connections (see instrument manufacturersinstructions).7.2.5 Acetylene Gas and RegulatorA cylinder of acety-le
41、ne equipped with a two-gage, two-stage pressure-reducingregulator with hose connections. (See instrument manufacturerinstructions.)TABLE 2 FAAS Flame and Operating Conditions for Each ElementElement Type of FlameAnalyticalWavelength, nmInterferencesARemedyAReferenceAg Air-C2H2(oxidizing) 328.1 I03,W
42、O42, MnO42,Cl,F B(2, 3)AlCN2O-C2H2(reducing) 309.3 ionization, SO42,VB,D,E(4)Ba N2O-C2H2(reducing) 553.6 ionization, large concentration CaD,F(1, 4)Bi Air-C2H2(oxidizing) 223.1 none knownCa Air-C2H2(oxidizing) 422.7 ionization (slight) and chemicalionizationD,E(1, 4)N2O-C2H2(reducing)Cd Air-C2H2(oxi
43、dizing) 228.8 none knownCoCAir-C2H2(oxidizing) 240.7 none knownCrCAir-C2H2(reducing) 357.9 Fe, Ni, oxidation state of CrB(4)Cu Air-C2H2(oxidizing) 324.8 none knownFe Air-C2H2(oxidizing) 248.3 high Ni concentration, SiB(1, 4)In Air-C2H2(oxidizing) 303.9 Al, Mg, Cu, Zn, HxPO4x3 B(5)K Air-C2H2(oxidizin
44、g) 766.5 ionizationD(1, 4)Li Air-C2H2(oxidizing) 670.8 ionizationD(6)Mg Air-C2H2(oxidizing) 285.2 chemical ionizationD,E(1, 4)N2O-C2H2(reducing)Mn Air-C2H2(oxidizing) 279.5 SiNa Air-C2H2(oxidizing) 589.6 ionizationE(1, 4)Ni Air-C2H2(oxidizing) 232.0 none knownPb Air-C2H2(oxidizing) 217.0283.3Ca, hig
45、h concentration SO42 B(7)Rb Air-C2H2(oxidizing) 780.0 ionizationD(1, 3)Sr Air-C2H2(oxidizing) 460.7 ionization and chemicalD,E(1, 3)N2O-C2H2(reducing) ionizationTl Air-C2H2(oxidizing) 276.8 none knownVa N2O-C2H2(reducing) 318.4 ionizationZn Air-C2H2(oxidizing) 213.9 none knownAHighconcentrationsofsi
46、liconinthesamplecancauseaninterferenceformanyoftheelementsinthistableandmaycauseaspirationproblems.Nomatterwhatelementsare being measured, if large amounts of silica are extracted from the samples, the samples should be allowed to stand for several hours and centrifuged or filtered toremove the sili
47、ca.BSamples are periodically analyzed by the method of additions to check for chemical interferences. If interferences are encountered, determinations must be made bythe standard additions method or, if the interferent is identified, it may be added to the standards.CSome compounds of these elements
48、 will not be dissolved by the procedure described here. When determining these elements, one should verify that the types ofcompounds suspected in the sample will dissolve using this procedure (see 12.2).DIonization interferences are controlled by bringing all solutions to 1000 ppm cesium (samples a
49、nd standards).E1000-ppm solution of lanthanum as a releasing agent is added to all samples and standards.FIn the presence of very large calcium concentrations (greater than 0.1 %) a molecular absorption from CaOH may be observed. This interference may be overcome byusing background corrections when analyzing for barium.D4185 1737.2.6 Nitrous Oxide Gas and RegulatorA cylinder ofnitrous oxide equipped with a two-gage, two-stage pressure-reducing regulator and hose connections. Heat tape with thetemperature controlled by a rheostat may be wound around these
