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

A very sensitive and selective procedure was developed for trace measuremen t of zirconium based on the cathodic adsorptive stripping voltammetry of th e zirconium-alizarin red S(ARS) complex at a carbon paste electrode (CPE). The 2nd-order derivative linear scan voltammograms of the zirconium-ARS com plex 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 ac id (0.1 mol l(-1))-potassium biphthalate (0.08 mol l(-1)) buffer solution ( pH 4.8) containing 4.0 x 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 i n the complex at the electrode. The detection limit was found to be 1.0 x 1 0(-10) mol l(-1) (S/N = 3) for 240 s accumulation. The linear range was 2.0 x 10(-10)-4.0 x 10(-7) mol l(-1). The developed method was applied to the determination of trace zirconium in the ore samples with satisfactory resul ts.