ASTM C738-94 (2020) pdf free.Standard Test Method for Lead and Cadmium Extracted from Glazed CeramicSurfaces.
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 4—As indicated in Section 1, this procedure covers the extractionand measurement 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.
Precision—In an analysis 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 laboratories 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.
ASTM C738 pdf download. The bias of this test method is further limited bythe ability to 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%. Table 1shows the mean value required in a large lot so that there willbe no more than one failure in 10 000 for a limit stated inaverage of six units and for a limit stated for the worst of sixunits,for a coefficient of variation of 60 %.
Purity of Reagents—Reagent 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 such specifications are available.2 Other 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.
Purity of Water—Unless otherwise indicated, referencesto water shall be understood to mean distilled water.
Acetic Acid (4 % by Volume)——Mix 1 volume of glacialacetic acid with 24 volumes of water.ASTM C738 pdf download.