Adsorption voltammetry of the scandium-alizarin red S complex onto a carbon paste electrode

For the first time, a new method is described for the determination of scan dium based on the cathodic adsorptive stripping of the scandium-alizarin re d S complex onto a carbon paste electrode. The second-order derivative line ar scan voltammograms of the complex are recorded by use of model JP-303 po larographic analyzer from 0.0 to - 1.0 V (versus SCE). Optimum conditions a re found to be: an acetic acid (0.36 mol l(-1))-potassium biphthalate (0.06 4 mol l(-1)) buffer solution (pH 4.0) containing 2.0 x 10(-5) mol l(-1) ali zarin red S, a preconcentration potential of 0.0 V, a preconcentration time of 60 s, a rest time of 10 s and a scan rate of 100 mV s(-1). The results show that the complex can be adsorbed on the surface of a carbon paste elec trode, yielding one peak at - 0.58 V, corresponding to the reduction of ali zarin red S in the complex at the electrode. The detection limit is: found to be 6.0 x 10(-10) mol l(-1) fur 3 min of preconcentration time. The linea r range is 1.0 x 10(-9) to 4.0 x 10(-7) mol l(-1). Application of the proce dure to the determination of scandium in the ore samples gave good results. (C) 2001 Elsevier Science B.V. All rights reserved.