SIMULTANEOUS DETERMINATION OF CADMIUM AND LEAD IN INDIUM METAL AND INDIUM SALTS BY DIFFERENTIAL-PULSE ANODIC-STRIPPING VOLTAMMETRY WITHOUT PRELIMINARY SEPARATION

This paper presents a method for the determination of trace levels of cadmium and lead in indium metal and indium salts, using differential pulse anodic stripping voltammetry at the hanging mercury drop electrode. The electrochemical activity of indium, which usually interferes in the determination of cadmium and lead, is inhibited by the addition of Sulforokanol L-3 (oxyethylated lauryl alcohol sodium sulphate salt). The base electrolyte was 0.2 M citrate buffer at pH 3.7. This electrolyte in the presence of 0.1% Sulforokanol L-3 makes possible the determination of 5 x 10(-9) M Cd(II) and 5 x 10(-9) M Pb(II) in the presence of 0.05 M In(III), i.e., 9.8 x 10(-6)% Cd and 1.8 x 10(-5)% Ph in indium. The accuracy and precision of the described method were satisfactory (the relative standard deviation was 4.9-10.6% for Cd and 3.3-6.9% for Pb).