Adsorption enrichment of some azo dye complexes on a carbon paste electrode and its application to the determination of small concentrations of cobalt and manganese

The azo dyes eriochrome black T, eriochrome blueblack R and eriochrome blueblack B and their complexes with cobalt, manganese and magnesium show adsorption enrichment on carbon paste electrodes, dependent on the composition of the electrode filling. This effect may be used for the determination of cobalt and manganese by a.c. voltammetry in the 10−7 to 10−6 M range. Standard deviation has been found to be ± 3.2 and ± 3.5%, respectively.