Analytical Sciences

Determination of Antimony in Steel by Differential Pulse Anodic Stripping Voltammetry at a Rotating Gold Film Electrode

Tatsuhiko TANAKA, * Takashi ISHIYAMA, and Kumi OKAMOTO

Faculty of Engineering, Science University of Tokyo, Kagurazaka, Shinjuku, Tokyo 162-8601, Japan

A simple and rapid procedure is presented for the reliable determination of antimony in steel based on differential pulseanodic stripping voltammetry without any removal of iron matrix. Optimum conditions included a supporting 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) was eliminated by simultaneously reducing it to iron(II) with the iodide. The generated iodine was reduced with L(+)-ascorbic acid. Arsenic(III), bismuth(III) and copper(II) interfered with the antimony determination severely. The proposed method has been successfully applied to the determination of antimony at the µg g^-1 level in steels within 50 min without any troublesome preconcentration steps using harmful chemicals. The detection limit (3sigma) with a deposition time of 300 s was 0.19 ng cm^-3 (1.6x10^-9 mol dm^-3).

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