Determination of traces of bismuth, copper and lead in cadmium by pulse polarography

Abstract

Traces of bismuth, copper and lead impurities in metallic cadmium and cadmium salts were determined, without separation, by pulse polarography. In chloride medium, these metals can be determined down to 4.10⁻⁸, 3.10⁻⁸ and 10⁻⁶M, respectively, i.e., 8.10⁻⁶, 2.10⁻⁶ and 2.10⁻⁴% in metallic cadmium, when analysing 1 M solution; 4.10⁻⁷% Cu can be detected in 5 M solutions. In acetate buffer, the sensitivity for bismuth and copper is about 2.10⁻⁸M or, respectively, 4.10⁻⁶ and 10⁻⁶% in cadmium. In ethylenediamine, down to 10⁻⁸M lead or 2.10⁻⁶% in cadmium can be determined.

The reciprocal tolerance was investigated for copper and bismuth in chloride and acetate solutions, and for copper and lead in ethylenediamine solutions. Finally, the method was applied to the analysis of various cadmium products commercially available and gave satisfactory sensitivity and resolution.