Determination of antimony in steel by differential pulse anodic stripping voltammetry at a rotating gold film electrode

A simple and rapid procedure is presented for the reliable determination of antimony in steel based on differential pulse anodic stripping voltammetry without any removal of iron matrix. Optimum conditions included a supporti ng electrolyte of 0.1 mol dm(-3) nitric acid-0.1 mol dm(-3) sulfuric acid, a pre-electrolysis of -0.5 V vs. the saturated calomel electrode for 300 s at a rotating gold film electrode, and subsequent stripping of the deposit on the electrode surface by a positive going potential scan at a rate of 40 mV s(-1). Antimony(V) was chemically reduced to antimony(III) by potassium iodide prior to voltammetric measurements. The interference of iron(III) w as eliminated by simultaneously reducing it to iron(II) with the iodide. Th e generated iodine was reduced with L(+)-ascorbic acid. Arsenic(III), bismu th(III) and copper(II) interfered with the antimony determination severely. The proposed method has been successfully applied to the determination of antimony at the mu g g(-1) level in steels within 50 min without any troubl esome preconcentration steps using harmful chemicals. The detection Limit ( 3 sigma) with a deposition time of 300 s was 0.19 ng cm(-3) (1.6x10(-9) mol dm(-3)).