Kinetic determination of trace amounts of copper(II) using its catalytic effect on the oxidation of chromotropic acid by hydrogen peroxide

Abstract

A catalytic reaction rate method is described for the determination of trace amounts of Cu^II. The method is based on the Cu^II-catalysed oxidation of chromotropic acid (the disodium salt of 4,5-dihydroxynaphthalene-2,7-disulphonic acid) by hydrogen peroxide. The reaction was followed spectrophotometrically by measuring the rate of change in absorbance at 430 nm. A detailed study of the kinetic characteristics of the above reaction has been carried out and the proposed method allows the determination of Cu^II in the range 12.7–190.6 ng ml^–1; the precision and accuracy were found to be within 1–2%. The method has been successfully applied to the determination of copper in tap and sea water samples and in biological materials.