Adsorption voltammetry of the mix-polynuclear complex of zirconium-calcium-alizarin red S at a carbon paste electrode

A novel new method is described for the determination of zirconium based on the cathodic adsorptive stripping of the mix-polynuclear complex of zircon ium-calcium-alizarin red S (ARS) at a carbon paste electrode (CPE). The sec ond-order derivative linear scan voltammograms of the adsorbed mix-polynucl ear complex of zirconium-calcium-ARS are recorded by model JP-303 polarogra phic analyzer from +0.20 to 0.80V (versus SCE). Optimal conditions are foun d to be: a glycine (0.096 M)-potassium biphthalate (0.036 M) buffer solutio n (pH 4.0) containing 8.0 x 10(-4) M Ca2+ and 2.0 x 10(-5) M ARS; accumulat ion potential, +0.20 V; accumulation time, 90 s; rest time, 10 s; scan rate , 500 mV s(-1). The results show that the complex can be adsorbed on the su rface of the CPE, yielding one peak at -0.50 V, corresponding to reduction of ARS in the complex at the electrode. The detection limit is found to be 4.0 x 10(-11) M with 4 min of accumulation time. The linear range is from 1 .0 x 10(-10) to 2.0 x 10(-7) M. Application of the procedure to the determi nation of zirconium in the ore samples gives good results. (C) 2001 Elsevie r Science B.V. All rights reserved.