Simultaneous determination of arsenic, antimony and tin by fast-scan differential-pulse polarography and its application to alloy steels

Arsenic, antimony and tin can be determined in the presence of one another by fast-scan differential-pulse polarography (FSDPP) on a single mercury drop in 1.5M hydrochloric acid. The reduction of As(III), Sb(III) and Sn(IV) to the metals is practically reversible and the reduction peaks are sufficiently separated. The lower limits of determination are 0.05, 0.005 and 0.001 μg/ml for As, Sb and Sn respectively, the calibration graphs exhibit very good linearity and the peak heights are reproducible. For application to alloy steels employed in nuclear technology, the elements to be determined must be separated from the matrix by extraction as their covalent bromides into toluene from concentrated sulphuric acid and back-extracted into the base electrolyte (1.5M HCl + 0.012M Br^? + 0.03M hydrazinium sulphate). The recoveries of As, Sb and Sn are 100, 95 and 92% respectively and the relative error of determination is a few per cent.