1、Designation: D4185 06 (Reapproved 2011)D4185 17Standard Practice 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 of
2、original adoption or, in the case of 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 practice test method covers the collection, dissolutio
3、n, and determination of trace metals in workplace atmospheres,by flame atomic absorption spectrophotometry. spectrophotometry (FAAS).1.2 The sensitivity, detection limit, and optimum working concentration for 23 metals are given in Table 1.1.3 The values stated in SI units are to be regarded as stan
4、dard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the app
5、licability of regulatorylimitations prior to use. (Specific safety precautionary statements are given in Section 9.)2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis of AtmospheresD1357 Practice for Planning the Sampli
6、ng of the Ambient AtmosphereD3195 Practice for Rotameter CalibrationD5337 Practice for Flow Rate Adjustment of Personal Sampling PumpsD7035 Test Method for Determination of Metals and Metalloids in Airborne Particulate Matter by Inductively Coupled PlasmaAtomic Emission Spectrometry (ICP-AES)3. Term
7、inology3.1 DefinitionsFor definitions of terms used in this practice, test method, refer to Terminology D1356.3.2 Definitions of Terms Specific to This Standard:3.2.1 blank signalthat signal which results from all added reagents and a clean membrane filter prepared and analyzed exactlyin the same wa
8、y as the samples.3.2.2 instrumental detection limitthat concentration of a given element which produces a signal three times the standarddeviation of the reagent blank signal.3.2.3 working range for an analytical precision better than 3 % 3 %the range of sample concentrations that will absorb 10to 7
9、0 % of the incident radiation (0.05 to 0.52 absorbance units).NOTE 1Values for instrumental detection limit may vary from instrument to instrument.4. Summary of Practice4.1 Workplace air samples are collected on membrane filters and treated with nitric acid to destroy the organic matrix and todissol
10、ve the metals present. The analysis is subsequently made by flame atomic absorption spectrophotometry (AAS).1 This practice test method is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.04 on Workplace AirQuality.Current edition appro
11、ved Oct. 1, 2011March 1, 2017. Published October 2011March 2017. Originally approved in 1990. Last previous edition approved in 20062011 asD4185 - 06.D4185 06 (2011). DOI: 10.1520/D4185-06R11.10.1520/D4185-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Custome
12、r Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the p
13、revious version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM
14、 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 Samples and standards are aspirated into an appropriate AAS flame. A hollow cathode or electrodeless discharge lamp forthe metal being determined provides a source of characteristic radiation ener
15、gy for that particular metal. The absorption of thischaracteristic energy by the atoms of interest in the flame is related to the concentration of the metal in the aspirated sample. Theflame and operating conditions for each element are listed in Table 2.4. Summary of Test Method4.1 Workplace air sa
16、mples are collected on membrane filters and treated with nitric acid to destroy the organic matrix and todissolve the metals present. The analysis is subsequently made by flame atomic absorption spectrophotometry (FAAS).4.2 Samples and standards are aspirated the flame of an absorption spectrophotom
17、eter. A hollow cathode or electrodelessdischarge lamp for the metal being determined provides a source of characteristic radiation energy for that particular metal. Theabsorption of this characteristic energy by the atoms of interest in the flame is related to the concentration of the metal in theas
18、pirated sample. The flame and operating conditions for each element are listed in Table 2.5. Significance and Use5.1 The health of workers in many industries is at risk through exposure by inhalation to toxic metals. Industrial hygienists andother public health professionals need to determine the ef
19、fectiveness of measures taken to control workers exposures, and this isgenerally achieved by making workplace air measurements. Exposure to some metal-containing particles has been demonstratedto cause dermatitis, skin ulcers, eye problems, chemical pneumonitis, and other physical disorders (41).35.
20、2 AASFAAS is capable of quantitatively determining most metals in air samples at the levels required by federal, state, andlocal occupational health and air pollution regulations. The analysis results can be used for the assessment of workplace exposuresto metals in workplace air.6. Interferences6.1
21、 In AASFAAS the occurrence of interferences is less common than in many other analytical techniques. Interferences canoccur, however, and when encountered are corrected for as indicated in the following sections. The known interferences andcorrection methods for each metal are indicated in Table 2.
22、The methods of standard additions and background monitoring andcorrection (8-12, 4, 8, 9) are used to identify the presence of an interference. Insofar as possible, the matrix of sample and standardare matched to minimize the possible interference.3 Boldface numbers in parentheses refer to the list
23、of references appended to these methods.TABLE 1 AASFAAS Instrumental 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 oxid
24、es)BAg 0.001 5 0.1 (metal) 0.01 (soluble compounds as Ag)Al 0.04 50 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
25、0.01 (elemental and compoundstotal dust)0.002 (elemental compoundsrespirable 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 (dus
26、t and mists as Cu)Fe 0.005 5 5 (iron oxide fume) 5 (soluble salts 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 Lim
27、it expressed for this elementNi 0.006 5 0.05 (elemental, soluble and 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, respirab
28、le dust or fume, as V2O5)Zn 0.002 1 10 (oxide dust as ZnO) 5 (oxide fume as ZnO)A These detection limits represent ideal laboratory conditions; variability due to sampling, digestion, reagents, and sample handling has not been taken into account.B Threshold Limit Values of Airborne Contaminants and
29、Physical Agents adopted by ACGIH for 19941995. Values are elemental concentrations except as noted.D4185 1726.2 Background or nonspecific absorption can occur from particles produced in the flame which can scatter light and producean apparent absorption signal. Light scattering may be encountered wh
30、en solutions of high salt content are being analyzed. Theyare most severe when measurements are made at shorter wavelengths (for example, below about 250 nm). Background absorptionmay also occur as the result of the formation of various molecular species which can absorb light. The background absorp
31、tion canbe accounted for by the use of background correction techniques (8).6.3 Spectral interferences are those interferences which result from an atom different from the one being measured that absorbsa portion of the radiation. Such interferences are extremely rare inAAS.FAAS. In some cases multi
32、element hollow cathode lampsmay cause a spectral interference by having closely adjacent emission lines from two different elements. In general, the use ofmultielement hollow cathode lamps is discouraged.6.4 Ionization interference occurs when easily ionized atoms are being measured. The degree to w
33、hich such atoms are ionizedis dependent upon the atomic concentration and the presence of other easily ionized atoms. This interference can be controlled bythe addition of a high concentration of another easily ionized element which will buffer the electron concentration in the flame.6.5 Chemical in
34、terferences occur in AASFAAS when species present in the sample cause variations in the degree to whichatoms are formed in the flame, or when different valence states of a single element have different absorption characteristics. SuchTABLE 2 AASFAAS Flame and Operating Conditions for Each ElementEle
35、ment Type of Flame AnalyticalWavelength, nm InterferencesA RemedyA ReferenceAg Air-C2H2 (oxidizing) 328.1 I03 , WO42, MnO42, Cl, F B (1,2)Ag Air-C2H2 (oxidizing) 328.1 I03 , WO42, MnO42, Cl, F B (2, 3)AlC N2O-C2H2 (reducing) 309.3 ionization, SO42, V B,D,E (3)AlC N2O-C2H2 (reducing) 309.3 ionization
36、, SO42, V B,D,E (4)Ba N2O-C2H2 (reducing) 553.6 ionization, large concentration Ca D,F (4,3)Ba N2O-C2H2 (reducing) 553.6 ionization, large concentration Ca D,F (1, 4)Bi Air-C2H2 (oxidizing) 223.1 none knownCa Air-C2H2 (oxidizing) 422.7 ionization (slight) and chemicalionizationD,E (4,3)Ca Air-C2H2 (
37、oxidizing) 422.7 ionization (slight) and chemicalionizationD,E (1, 4)N2O-C2H2 (reducing)Cd Air-C2H2 (oxidizing) 228.8 none knownCoC Air-C2H2 (oxidizing) 240.7 none knownCrC Air-C2H2 (reducing) 357.9 Fe, Ni, oxidation state of Cr B (3)CrC Air-C2H2 (reducing) 357.9 Fe, Ni, oxidation state of Cr B (4)C
38、u Air-C2H2 (oxidizing) 324.8 none knownFe Air-C2H2 (oxidizing) 248.3 high Ni concentration, Si B (4,3)Fe Air-C2H2 (oxidizing) 248.3 high Ni concentration, Si B (1, 4)In Air-C2H2 (oxidizing) 303.9 Al, Mg, Cu, Zn, HxPO4x3 B (5)K Air-C2H2 (oxidizing) 766.5 ionization D (4,3)K Air-C2H2 (oxidizing) 766.5
39、 ionization D (1, 4)Li Air-C2H2 (oxidizing) 670.8 ionization D (6)Mg Air-C2H2 (oxidizing) 285.2 chemical ionization D,E (4,3)Mg Air-C2H2 (oxidizing) 285.2 chemical ionization D,E (1, 4)N2O-C2H2 (reducing)Mn Air-C2H2 (oxidizing) 279.5 SiNa Air-C2H2 (oxidizing) 589.6 ionization E (4,3)Na Air-C2H2 (oxi
40、dizing) 589.6 ionization E (1, 4)Ni Air-C2H2 (oxidizing) 232.0 none knownPb Air-C2H2 (oxidizing) 217.0283.3Ca, high concentration SO42 B (7)Rb Air-C2H2 (oxidizing) 780.0 ionization D (4,2)Rb Air-C2H2 (oxidizing) 780.0 ionization D (1, 3)Sr Air-C2H2 (oxidizing) 460.7 ionization and chemical D,E (4,2)
41、Sr Air-C2H2 (oxidizing) 460.7 ionization and chemical D,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 knownA Highconcentrationsofsiliconinthesamplecancauseaninterferenceformanyoftheelementsinthi
42、stableandmaycauseaspirationproblems.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 silica.B Samples are periodically analyzed by the method of additio
43、ns 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.C Some compounds of these elements will not be dissolved by the procedure described here. When
44、determining these elements, one should verify that the types ofcompounds suspected in the sample will dissolve using this procedure (see 12.2).D Ionization interferences are controlled by bringing all solutions to 1000 ppm cesium (samples and standards).E 1000-ppm solution of lanthanum as a releasin
45、g agent is added to all samples and standards.F In 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 173interferences may be control
46、led by adjusting the sample matrix or by the method of standard additions (9). Also, the use oflanthanum as a releasing element minimizes the interference from the formation of involatilenonvolatile compounds in the flame.Lanthanum forms involatilenonvolatile compounds preferentially with the interf
47、erent so that the analyte staysremains free.6.6 Physical interferences may result if the physical properties of the samples vary significantly. Changes in viscosity andsurface tension can affect the sample aspiration rate and thus cause erroneous results. Sample dilution or the method of standardadd
48、itions, or both, are used to correct such interferences. High concentrations of silica in the sample can cause aspiration problems.No matter what elements are being determined, if large amounts of silica are extracted from the samples, they shall be allowedto stand for several hours and centrifuged
49、or filtered to remove the silica.6.7 This procedure describes a generalized method for sample preparation, which is applicable to the majority of samples. Thereare some relatively rare chemical forms of a few of the elements listed in Table 1 that will not be dissolved by this procedure. Ifsuch chemical forms are suspected, results obtained using this procedure shall be compared with those obtained using anappropriately altered dissolution procedure.Alternatively, the results may be compared with values obtained using a technique thatdoes not require di
