ASTM C738-94(R2020) pdf free download

ASTM C738-94(R2020) pdf free download.Standard Test Method for Lead and Cadmium Extracted from Glazed Ceramic Surfaces
1. Scope
1.1 This test method covers the precise determination of lead and cadmium extracted by acetic acid from glazed ceramic surfaces. The procedure of extraction may be expected to accelerate the release of lead from the glaze and to serve, therefore, as a severe test that is unlikely to be matched under the actual conditions of usage of such ceramic ware. This test method is specific for lead and cadmium. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
5. Reagents
5.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Commit- tee on Analytical Reagents of the American Chemical Society, where such specifications are available. 2 Other grades may be used provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 5.2 Purity ofWater—Unless otherwise indicated, references to water shall be understood to mean distilled water. 5.3 Acetic Acid (4 % by Volume)—Mix 1 volume of glacial acetic acid with 24 volumes of water.5.4 Detergent Wash—Use detergent designed for washing household dishes by hand. Mix with lukewarm tap water according to product instructions. 5.5 Lead Nitrate Solution (1000-ppm Pb)—Dissolve 1.598 g of lead nitrate (Pb(NO 3 ) 2 ) in 4 % acetic acid and dilute to 1 L with 4 % acetic acid. Commercially available standard lead solutions may also be used. 5.6 Hydrochloric Acid (1 % by weight)—Mix 1 volume of concentrated hydrochloric acid (HCl, sp gr 1.19) with 37 volumes of water. 5.7 Cadmium Solution (1000-ppm Cd)—Dissolve 0.9273 g ofanhydrous cadmium sulfate in approximately 250 mLof1 % HCl (see 5.6) and dilute to 500 mL with 1 % HCl. Commer- cially available standard cadmium solutions may also be used.
6. Procedure
N OTE 2—Take a method control through entire procedure. Use a laboratory beaker with dimensions similar to ware being tested. 6.1 Preparation of Sample—Take, at random, six identical units and the method control vessel and clean with detergent wash. Then rinse with tap water followed by distilled water. Dry, and fill each unit with 4 % acetic acid to within approxi- mately 6 to 7 mm ( 1 ⁄ 4 in.) of overflowing. (Distance shall be measured along the surface of the item tested, not in the vertical direction.) Record the volume ofacid required for each unit in the sample (Note 3). Cover each unit with fully opaque glass plate (so that extraction is carried out in total darkness) o prevent evaporation of solution, avoiding contact between cover and surface of leaching solution. (If opaque glass is not available, cover glass with aluminum foil or other material to prevent exposure to light.) Let stand for 24 h at room temperature (20 to 24 °C (68 to 75 °F)). N OTE 3—Ifthe sample unit is extremely shallow, or ifit has an irregular brim, the analyst should be aware of evaporation of leaching solution. If such a loss is anticipated, record the headspace upon filling the vessel to 6 to 7 mm ( 1 ⁄ 4 in.) of the brim. Adjust to the same headspace with 4 % acetic acid after the 24-h leaching. Stir the solution and proceed with the determination.