Catalytic spectrophotometric determination of trace amounts of copper(II) with 3-hydroxy-2-naphthoic acid.

A very sensitive catalytic spectrophotometric method for the determination of copper(II) concentrations as low as 0.06 ng/ml is described. This method is based on the oxidation of 3-hydroxy-2-naphthoic acid by hydrogen peroxide in ammoniacal medium, catalysed by copper(II). The results of an exhaustive study of interferences are given. The new method is applied to determination of copper in atmospheric aerosol samples. A qualitative study of the mechanism by means of electron paramagnetic resonance spectroscopy is also included.