Catalytic determination of copper(II) using the iron(III)--thiosulphate reaction and its application to metals and biological samples.

Abstract

A spectrophotometric method has been developed for the catalytic determination of copper(II) by using an iron(III)-thiosulphate reaction, with a much higher concentration of iron than thiosulphate, in the absence of thiocyanate. A well defined absorption spectrum was obtained and the colour fading reaction of the unstable iron(III)-thiosulphate complex is discussed. Only slight influences of iron(III) and other foreign ions on the determination were found. The linear range of the calibration graph is 0–2.0 µg of copper and the standard deviation is 0.036 µg for five determinations of 1.0 µg of copper. The detection limit is about 0.05 µg of copper. The method has been applied successfully to the analysis of some metals and biological samples without any separation.