DETERMINATION OF TRACE CHROMIUM(III) BY LINEAR SWEEP ADSORPTION VOLTAMMETRY

A very sensitive electrochemical adsorptive voltammetric procedure for the determination of trace chromium, based on the adsorption characteristics of the chromium(III) complex with 2-(5'-bromo-2'-pyridylazo)-5-diethylamino-phenol (5-Br-PADAP) at a mercury electrode in HAc+NaAc (pH = 3.2), is described. Experimental results show that the best base solution consists of 0.5 mol/1 acetic acid, 0.015 mol/1 sodium acetate, 6×10-5 mol/1 5-Br-PADAP and 10% alcohol. The detection limit and linear range of the method are 9×10-10 mol/1 and 3×10-9-9×10-8 mol/1, respectively. The method has been used to determine the total chromium content in millet and rice. © 1990.