A method for determining 480 mg m
-2of Tl, Pb, Cd, Sn, In, Cu and Sb in zinc electroplated films on steel sheets has been developed. Although (1+9)H
2SO
4 containing 100 μg cm
-3 of
N,
N-dimethylthiourea (Acid A) was capable of dissolving the films without dissolution of the steel sheets, Sb was reduced in the presence of nascent hydrogen to escape as volatile SbH
3 and Cu was incompletely dissolved to remain on the steel sheets. Dissolution with conc. HNO
3 under cooling resulted in the complete recovery of Sb and Cu, although the steel sheets were dissolved a little. Therefore, dissolution with Acid A was adopted for the determination of Tl, Pb, Cd, Sn and In, and conc. HNO
3 for Cu and Sb. Nitric acid was removed by fuming with H
2SO
4 after dissolution of the films. Thallium, Pb, Cd, Sn, In, Cu and Sb were determined by differential pulse anodic stripping voltammetry according to the procedure described in a previous paper. A relative standard deviation (
n=5) of about 3% was obtained. In addition, the quantities of these elements in the films were correlated with the concentrations of the elements in the electroplating baths.
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