1、Designation: C 738 94 (Reapproved 2006)Standard Test Method forLead and Cadmium Extracted from Glazed CeramicSurfaces1This standard is issued under the fixed designation C 738; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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.1. Scope1.1 This test method covers the precise determination oflead and cadmium extracted by acetic acid from glazed ceram
3、icsurfaces. 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 st
4、ated 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-priat
5、e safety 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 spectro
6、s-copy.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 cadm
7、ium, 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, characteris
8、tic 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
9、.4.3 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 te
10、sts. 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 ofsuffi
11、ciently 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 Deterg
12、ent 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
13、 leadsolutions 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 an
14、d ASTM, 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 Feb. 15, 2006. Published February 2006. Originallypublished approved in 1972. Last pre
15、vious edition approved in 1999 as C 738 94 (1999).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 LaboratoryChemicals, BDH Ltd., Poo
16、le, 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 weight)Mix 1 volume of
17、concentrated 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 may also be used.6
18、. 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 followed by distille
19、d 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). Cover each unit wit
20、h 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 to light.) Let stand
21、 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 in.) of the brim.
22、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 concentrations of 0.
23、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 theleaching solution and rem
24、ove 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 Pb by accurately t
25、ransferring 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 glass, and swirl to com
26、plete 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 1-ppm Cd. Concentr
27、ate 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 measurement of lead an
28、d 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 analysis of variance st
29、udy 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 laboratories and samples is
30、 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 obtain representati
31、ve 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 value required in a lar
32、ge 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 w orst of six units, fora coefficient of variation of 60 %.9. Keywords9.1 cadmium; glazed ceramic surfaces; lead3Moore, C. F., Transactions, Journal of British Cerami
33、c 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 0.05C 738 94 (2006)2ASTM International takes no po
34、sition respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibi
35、lity.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to A
36、STM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the addres
37、s 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).C 738 94 (2006)3
