1、Designation: C738 94 (Reapproved 2011)Standard Test Method forLead and Cadmium Extracted from Glazed CeramicSurfaces1This standard is issued under the fixed designation C738; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 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 precise determination oflead and cadmium extracted by acetic acid from glazed ceramics
3、urfaces. The procedure of extraction may be expected toaccelerate the release of lead from the glaze and to serve,therefore, as a severe test that is unlikely to be matched underthe actual conditions of usage of such ceramic ware. This testmethod is specific for lead and cadmium.1.2 The values state
4、d in SI (metric) units are to be regardedas the standard. The values given in parentheses are forinformation only.1.3 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 s
5、afety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Summary of Test Method2.1 Lead and cadmium are extracted from the test article byleaching with 4 % acetic acid for 24 h at 20 to 24C (68 to75F) and are measured by flame atomic absorption spectros-c
6、opy.3. Interferences3.1 There are no interferences when instrumental back-ground correction and light sources specific for lead andcadmium are used.4. Apparatus4.1 Atomic Absorption Spectrometer equipped with lightsources (hollow cathode or electrodeless discharge lamps)specific for lead and cadmium
7、, instrumental background cor-rection, and a 4-in. (102-mm) single slot or Boling burner head.Digital concentration readout may be used. Use air-acetyleneflame, instrumental background correction, and operating con-ditions recommended by instrument manufacturer. Using theseconditions, characteristic
8、 concentration (concentration thatgives 0.0044 absorbance) should be approximately (620 %)0.2 and 0.45 ppm for Pb measured at 217.0 and 283.3 nm,respectively. Characteristic concentration should be approxi-mately (620 %) 0.02 ppm for Cd.NOTE 11 ppm = 1 g/mL.4.2 Lead Lamp, set at 283.3 or 217.0 nm.4.
9、3 Cadmium Lamp, set at 228.8 nm.4.4 Glassware of chemically resistant borosilicate glass, tomake reagents and solutions. Clean by rinsing with dilute nitricacid (10 % by volume) followed by copious quantities of water.5. Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests
10、. 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 such specifications are available.2Other grades may beused provided it is first ascertained that the reagent is ofsufficie
11、ntly high purity to permit its use without lessening theaccuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean distilled water.5.3 Acetic Acid (4 % by Volume)Mix 1 volume of glacialacetic acid with 24 volumes of water.5.4 Detergent
12、 WashUse detergent designed for washinghousehold dishes by hand. Mix with lukewarm tap wateraccording to product instructions.5.5 Lead Nitrate Solution (1000-ppm Pb)Dissolve 1.598g of lead nitrate (Pb(NO3)2) in 4 % acetic acid and dilute to 1L with 4 % acetic acid. Commercially available standard le
13、adsolutions may also be used.1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and Related Products and is the direct responsibility of SubcommitteeC21.03 on Methods for Whitewares and Environmental Concerns. This test methodwas developed jointly by the AOAC and A
14、STM, and adopted official final action bythe Association of Official Analytical Chemists (method 973.32 AOAC OffcialMethods of Analysis (1990) 15th ed, AOAC International, Arlington, VA.Current edition approved March 1, 2011. Published March 2011. Originallypublished approved in 1972. Last previous
15、edition approved in 2006 as C738 94 (2006). DOI: 10.1520/C0738-94R11.2Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemi
16、cals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.6 Hydrochloric Acid (1 % by wei
17、ght)Mix 1 volume ofconcentrated hydrochloric acid (HCl, sp gr 1.19) with 37volumes of water.5.7 Cadmium Solution (1000-ppm Cd)Dissolve 0.9273 gof anhydrous cadmium sulfate in approximately 250 mLof 1 %HCl (see 5.6) and dilute to 500 mL with 1 % HCl. Commer-cially available standard cadmium solutions
18、 may also be used.6. ProcedureNOTE 2Take a method control through entire procedure. Use alaboratory beaker with dimensions similar to ware being tested.6.1 Preparation of SampleTake, at random, six identicalunits and the method control vessel and clean with detergentwash. Then rinse with tap water f
19、ollowed by distilled water.Dry, and fill each unit with 4 % acetic acid to within approxi-mately 6 to 7 mm (14 in.) of overflowing. (Distance shall bemeasured along the surface of the item tested, not in thevertical direction.) Record the volume of acid required for eachunit in the sample (Note 3).
20、Cover each unit with fully opaqueglass plate (so that extraction is carried out in total darkness) oprevent evaporation of solution, avoiding contact betweencover and surface of leaching solution. (If opaque glass is notavailable, cover glass with aluminum foil or other material toprevent exposure t
21、o light.) Let stand for 24 h at roomtemperature (20 to 24C (68 to 75F).NOTE 3If the sample unit is extremely shallow, or if it has an irregularbrim, the analyst should be aware of evaporation of leaching solution. Ifsuch a loss is anticipated, record the headspace upon filling the vessel to6to7mm(14
22、 in.) of the brim. Adjust to the same headspace with 4 %acetic acid after the 24-h leaching. Stir the solution and proceed with thedetermination.6.2 Preparation of Standards:6.2.1 Lead StandardsDilute lead nitrate solution (see 5.5)with acetic acid (see 5.3) to obtain working standards havingfinal c
23、oncentrations of 0.0-, 1-, 2-, 3-, 5-, and 10-ppm Pb.6.2.2 Cadmium StandardsDilute cadmium stock solution(see 5.7) with acetic acid (5.3) to obtain working standardshaving final concentrations of 0.0-, 0.1-, 0.2-, 0.3-, 0.5-, and1.0-ppm Cd.6.3 Determination of Lead by Atomic AbsorptionStir theleachi
24、ng solution and remove a portion by pipetting into aclean flask. Use lead lamp (4.2) and concomitantly measureabsorbance of lead working standards (6.2.1) and leach solu-tions. Dilute with 4 % acetic acid if leach solutions containover 10-ppm Pb. Concentrate leach solutions containing lessthan 1-ppm
25、 Pb by accurately transferring a minimum of 50.0mL of solution to a 250-mL beaker and evaporating almost todryness on a steam bath. Add 1 mL of HCl, then evaporate todryness. Dissolve the residue in 4 % acetic acid by addingexactly 0.1 volume of solution taken for concentration, coverwith watch glas
26、s, and swirl to complete dissolution. Calculatelead concentration (ppm Pb) of leach solution by comparison tostandard curve.6.4 Determination of Cadmium by Atomic AbsorptionProceed as in 6.3 using the cadmium lamp (4.3) and standards(6.2.2). Dilute with 4 % acetic acid if leach solutions containover
27、 1-ppm Cd. Concentrate leach solutions containing lessthan 0.1-ppm Cd as in 6.3.7. Report7.1 Report the type of units tested, the volume of acid used,and the lead and cadmium leached in parts per million for eachunit tested.NOTE 4As indicated in Section 1, this procedure covers the extractionand mea
28、surement of lead and cadmium from ceramic surfaces. It isgeneral in that it does not specify specific sample unit types. For specialend uses, as for example, process control or interlaboratory testing, aspecific size and type of sample unit should be used.8. Precision and Bias8.1 PrecisionIn an anal
29、ysis of variance study from eightlaboratories, the standard deviation between laboratories was0.06 mg/L for lead and 0.007 mg/L for cadmium. The withinlaboratory precision had a standard deviation of 0.04 mg/L forlead and 0.004 mg/L for cadmium. The standard deviation forinteraction between laborato
30、ries and samples is 0.06 mg/L forlead and 0.010 mg/L for cadmium. Reproducibility is definedas the square root of the sum of the three component variances.The reproducibilities were 0.10 mg/L for lead and 0.013 mg/Lfor cadmium.8.2 BiasThe bias of this test method is further limited bythe ability to
31、obtain representative samples of the statisticaluniverse being sampled. An analysis of large populations (100to 500) has shown that the lead and cadmium release dataconformed to a Pearson III distribution with a coefficient ofvariation between 30 and 140 %, typically 60 %.3Table 1shows the mean valu
32、e required in a large lot so that there willbe no more than 1 failure in 10 000 for a limit stated in averageof six units and for a limit stated for the worst of six units, fora coefficient of variation of 60 %.9. Keywords9.1 cadmium; glazed ceramic surfaces; lead3Moore, C. F., Transactions, Journal
33、 of British Ceramic Society, Vol 76 (3),1977, pp. 5257.TABLE 1 Mean Value Required in a Large Lot for Failure Rate1/10 000 with Coefficient of Variation 60 %Limit (ppm) Mean of 6Worstof6(Mean of 1)7 3.21 1.455 2.29 1.032.5 1.15 0.520.7 0.32 0.140.5 0.23 0.100.25 0.11 0.05C738 94 (2011)2ASTM Internat
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37、ds, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C738 94 (2011)3
