1、Designation: D 3335 85a (Reapproved 2005)Standard Test Method forLow Concentrations of Lead, Cadmium, and Cobalt in Paintby Atomic Absorption Spectroscopy1This standard is issued under the fixed designation D 3335; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. S
3、cope1.1 This test method covers the determination of lead2contents between 0.01 and 5 %, cadmium contents between 50and 150 ppm (mg/kg), and cobalt contents between 50 and2000 ppm (mg/kg) present in the nonvolatile portion of liquidcoatings or contained in dried films. There is no reason tobelieve t
4、hat higher levels of all three elements could not bedetermined by this test method, provided that appropriatedilutions and adjustments in specimen size and reagent quan-tities are made.1.2 Only pigmented coatings were used for evaluating thistest method, but there is no reason to believe that varnis
5、hes andlacquers could not be analyzed successfully, provided thatappropriate precautions are taken.1.3 This test method is not applicable to the determinationof lead in samples containing antimony pigments (low recov-eries are obtained).1.4 If lead is present in the sample to be analyzed in theform
6、of an organic lead compound at a concentration greaterthan 0.1 %, small losses of lead may occur, resulting in slightlypoorer precision than shown in Section 12.1.5 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 This stand
7、ard 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 hazardstatements ar
8、e given in Section 7.2. Referenced Documents2.1 ASTM Standards:3D 1193 Specification for Reagent WaterD 2832 Guide for Determining Volatile and NonvolatileContent of Paint and Related Coatings3. Summary of Test Method3.1 The specimen of liquid coating or dried film is preparedfor analysis by dry ash
9、ing. The content of lead, cadmium, orcobalt of an acid extract of the ash is determined by atomicabsorption spectroscopy.4. Significance and Use4.1 The permissible level of heavy metals in certain coat-ings is specified by governmental regulatory agencies. This testmethod provides a fully documented
10、 procedure for determininglow concentrations of lead, cadmium, and cobalt present inboth water and solvent-reducible coatings to determine com-pliance.5. Apparatus5.1 Atomic Absorption Spectrophotometer, consisting of anatomizer and either a single- or three-slot burner; gas pressureregulating and m
11、etering devices for air and acetylene; lead,cadmium, and cobalt source lamps4with a regulated constant-current supply; a monochromator and associated optics; aphotosensitive detector connected to an electronic amplifier;and a readout device.1This test method is under the jurisdiction of ASTM Committ
12、ee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved Jan. 1, 2005. Published February 2005. Originallyapproved in 1974. Last previous edition approved in 199
13、9 as D 3335 85a (1999).2Vandeberg, J. T., Swafford, H. D., and Scott, R. W., “Determination of LowConcentrations of Lead in Paint,” Journal of Paint Technology, Vol 47, No. 604,May 1975.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceas
14、tm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Both hollow cathode lamps and electrodeless discharge lamps have been foundsatisfactory for this purpose.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, We
15、st Conshohocken, PA 19428-2959, United States.5.2 Muffle Furnace, capable of maintaining 500 6 10C.5.3 Crucibles, wide-form, porcelain, glazed inside and out-side except for the outside bottom surface, approximately30-mL capacity, 50-mm rim diameter and 31-mm height.55.4 Hot Plate, with variable sur
16、face temperature controlover the range from 70 to 200C.5.5 High-Silica Glass Beakers,6100 and 250-mL.5.6 Volumetric Flasks, 50, 100, and 1000-mL.5.7 Dropping Bottles,14 or 7 or 15-mL (12-oz) capacity.5.8 Glass or Disposable Syringes, 5 or 10-mL capacity.5.9 Pipets, 1, 2, 5, and 10-mL capacity.5.10 P
17、aint Shaker.5.11 Paint Draw-Down Bar.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where suc
18、h specifications are available.7Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean
19、reagent grade waterconforming to Type II of Specification D 1193.6.3 Ammonium Acetate Solution (50 % weight/volume)Dissolve 500 g of ammonium acetate (NH4C2H3O2) in waterand dilute to 1 L.6.4 Ammonium Acetate Diluting SolutionAdd 50 mL ofHNO3(sp gr 1.42) to 150 mL of 50 % weight/volume ammo-nium ace
20、tate solution and dilute to 1 L.6.5 Cadmium Standard Stock Solution (1 mg/mL)Dissolve 2.1032 g of cadmium nitrate (Cd(NO3)2)in10mLofwater, add 10 mL of HNO3(sp gr 1.42), and dilute to 1 L.6.6 Cobalt Standard Stock Solution (1 mg/mL)Dissolve4.9387 g of cobalt nitrate hexahydrate (Co(NO3)26H2O) in 10m
21、L of water, add 10 mL of HNO3(sp gr 1.42), and dilute to 1L.6.7 Lead Standard Stock Solution (1 mg/mL)Dissolve1.5980 g of lead nitrate (Pb(NO3)2) in 10 mL of water, add 10mL of HNO3(sp gr 1.42), and dilute to 1 L.NOTE 110.00 mg/mL concentrations of cadmium, lead, silver andzinc are available as SRM
22、2121; and the same concentration of cobalt,copper, iron and nickel as SRM 2124 from: Office of Standard ReferenceMaterials, Room B-311, Chemistry Building, NIST, Washington, DC20234.6.8 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).6.9 Nitric Acid (1 + 1)Add 1 volume of HNO3(sp gr1.42) to 1
23、 volume of water.7. Hazards7.1 Concentrated nitric acid is corrosive and may causesevere burns of the skin or eyes; the vapor is irritating tomucous membranes. Use care in handling this acidic substance.Refer to suppliers Material Safety Data Sheet.7.2 Use only a rubber bulb aspirator for pipeting l
24、iquids.8. Calibration and Standardization8.1 Prepare 100-mL quantities of at least four standardsolutions bracketing the expected lead, cadmium, or cobaltconcentration in the sample to be tested. To suitable aliquots ofthe 1 mg/mL standard lead, cadmium, or cobalt solution, add 5mL of HNO3(sp gr 1.4
25、2) and 15 mL of 50 % ammoniumacetate solution. Dilute to 100 mL with water.8.2 Operational instructions for atomic absorption spectro-photometers vary with different models. Consult the manufac-turers literature for establishing optimum conditions for thespecific instrument used.8.3 Turn the instrum
26、ent on and set the wavelength to the283.3-nm lead line, the 228.8-nm cadmium line, or the240.7-nm cobalt line. Apply the current recommended by themanufacturer to the lead, cadmium, or cobalt source lamp.Allow the instrument to warm up for about 15 min and set theslit width. Adjust the air and acety
27、lene pressure or flow ratesand ignite the burner in accordance with the manufacturersinstructions.8.4 Aspirate water to rinse the atomizer chamber. Aspirate astandard solution and make any necessary readjustment ininstrument parameters to obtain maximum absorption.8.5 Aspirate each of the appropriat
28、e standard solutions andrecord the corresponding instrument readings. Aspirate waterbetween each standard.8.6 Construct a calibration curve on linear graph paper byplotting the absorbance versus concentration (micrograms permillilitre) for each standard solution. Alternatively, the calibra-tion resu
29、lts may be stored in the instrument, if so equipped, andreadings made directly in concentration.9. Procedure9.1 If the sample is a liquid coating, mix it until homoge-neous, preferably on a mechanical shaker. Determine thenonvolatile content in accordance with Guide D 2832.9.2 Prepare at least two r
30、eplicate specimens by weighing bydifference from a dropping bottle or syringe approximately 2 to3 g of the mixed liquid coating, or by directly weighingapproximately 1 to2gofdried paint film, into a 30-mLporcelain crucible. Weigh to 0.1 mg.NOTE 2The specimen size called for will give a concentration
31、 ofapproximately 10 to 20 g/mL lead in the final diluted solution for paintscontaining approximately 500 ppm (mg/kg) lead, based on the solids. If5The sole source of supply of No. 25007 crucibles, known to the committee atthis time is Coors Manufacturer. If you are aware of alternative suppliers, pl
32、easeprovide this information to ASTM International Headquarters. Your comments willreceive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.6The sole source of supply of Vycor beakers, known to the committee at thistime is Corning Glass Co., Houghton Par
33、k, Corning, NY 14831. If you are aware ofalternative suppliers, please provide this information to ASTM Headquarters. Yourcomments will receive careful consideration at a meeting of the responsibletechnical committee,1which you may attend.7Reagent Chemicals, American Chemical Society Specifications,
34、 AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc.
35、 (USPC), Rockville,MD.D 3335 85a (2005)2the material is estimated to contain more or less than 500 ppm lead, thequantity taken should be adjusted accordingly. In the event that signifi-cantly less than 500 ppm lead is expected, a 250-mL high-silica beakermay be used in place of the crucible to accom
36、modate specimen weights upto 10 g. The size specified will give a concentration of approximately 2 to4 g/mL cadmium in the final diluted solution for paints containingapproximately 100 ppm cadmium, based on the solids. The size specifiedwill give a concentration of approximately 10 to 20 g/mL cobalt
37、 in thefinal diluted solution for paints containing approximately 500 ppm cobalt,based on the solids.NOTE 3Recover dried paint films from previously coated substrates(being careful not to remove any underlying material from the substrate)or prepare in the laboratory from liquid samples. For the labo
38、ratorypreparation, flow some of the well-mixed sample onto a clean glass plate.The use of a paint draw-down bar is recommended to obtain a uniform wetfilm thickness not exceeding 2 mils (50 m). Allow the film to dry in anoven at 105C for a minimum of 1 h. Scrape the dried film off the glassplate, pr
39、eferably with a single-edge razor blade.9.3 Place the crucible (or beaker) containing the liquidcoating on a hot plate and slowly increase the temperature untilthe material is dried. With some types of coatings, an initialoven-drying at 105C may be necessary to remove solventswithout incurring losse
40、s due to spattering.9.4 When the specimen appears to be dry or when startingwith a dried film, gradually increase the temperature of the hotplate until the material chars.9.5 After charring is complete, place the container in apreheated muffle furnace and ash at 475 to 500C.NOTE 4Ashing at temperatu
41、res in excess of 500C may result in theloss of some lead by volatilization.9.6 When the ashing appears to be complete (do not exceed1 to 2 h), remove the crucible or beaker from the muffle furnaceand allow it to cool to room temperature. Break up the ash intofine particles with a glass stirring rod,
42、 leaving the rod with thecontainer through the filtering step.9.7 Add 10 mL of HNO3(1 + 1), taking care to avoid lossesdue to spattering in case the ash reacts vigorously with the acid.Heat carefully on a hot plate until 2 to 3 mL of solution remain.Add an additional 10 mLof HNO3(1 + 1) and continue
43、 heatingon the hot plate until less than 5 mL of the solution remains.9.8 Filter the solution through medium-porosity filter paperinto a 50-mL volumetric flask. If the filtrate is not clear, refilterthrough fine-porosity filter paper. Wash the container threetimes with 2.5 mL of hot ammonium acetate
44、 solution (6.3),each time transferring the washings to the filter paper. Wash thefilter paper several times with water. Adjust the volume to 50mL with water and mix.9.9 Aspirate the test solution and determine the absorbancein the same manner in which the instrument was calibrated.Determine the conc
45、entration of lead, cadmium, or cobalt inmicrograms per millilitre from the calibration curve. If theabsorbance is above the range covered by the calibration curve,dilute an aliquot of the sample solution to a suitable volumewith ammonium acetate diluting solution.NOTE 5For maximum accuracy, calibrat
46、ion and standardization (Sec-tion 8) should be completed just prior to aspirating the sample solution.NOTE 6The method of standard additions may be used to improve theaccuracy of the analysis. This method is particularly recommended for usewith unknown samples where matrix effects may be potentially
47、 signifi-cant. For a detailed description of the procedure and calculations used inthe method of standard additions, consult a standard text on atomicabsorption spectroscopy or the instruction manual provided by theinstrument manufacturer.10. Calculation10.1 Calculate the mean concentration of lead,
48、 cadmium, orcobalt in the nonvolatile portion of the sample as follows:lead, cadmium or cobalt, ppm mg/kg! in nonvolatile (1)5 C 3 F 3 5000!/NV 3 S!where:C = concentration of lead, cadmium, or cobalt in theaspirated specimen solution, (g/mL),F = dilution factor from 9.9 (volume diluted to/volumeof a
49、liquot),5000 = factor derived from multiplying the 50-mL volumeobtained in procedure in 9.8 by 100 (to convert NVused to a whole number) and 106(to obtain ppm),then dividing by 106(to convert grams of sample tog),NV = percent nonvolatile of paint sample (use 100 ifsample was a dried film), andS = sample, g.11. Report11.1 Report the lead, cadmium, or cobalt content of thenonvolatile content of the sample and whether the analysis wasconducted on a liquid coating or a dried film.12. Precision and Bias812.1 The precision estimates are based on an inter
