Carbon paste electrode for trace zirconium(iv) determination by adsorptionvoltammetry

Abstract

A very sensitive and selective procedure was developed for trace measurement of zirconium based on the cathodic adsorptive stripping voltammetry of the zirconium–alizarin red S(ARS) complex at a carbon paste electrode (CPE). The 2nd-order derivative linear scan voltammograms of the zirconium–ARS complex were recorded by a model JP-303 polarographic analyzer from 0.0 to −1.0 V (vs. SCE). Optimal analytical conditions were found to be: an acetic acid (0.1 mol l⁻¹)–potassium biphthalate (0.08 mol l⁻¹) buffer solution (pH 4.8) containing 4.0 × 10⁻⁶ mol l⁻¹ ARS; accumulation potential, 0.0 V; accumulation time, 180 or 90 s; rest time, 10 s; scan rate, 250 mV s⁻¹. The results showed that the complex can be adsorbed on the surface of the CPE, yielding one peak at −0.51 V, corresponding to the reduction of ARS in the complex at the electrode. The detection limit was found to be 1.0 × 10⁻¹⁰ mol l⁻¹ (S/N = 3) for 240 s accumulation. The linear range was 2.0 × 10⁻¹⁰–4.0 × 10⁻⁷ mol l⁻¹. The developed method was applied to the determination of trace zirconium in the ore samples with satisfactory results.