Electrooxidation and Determination of Dopamine Using a Nafion -Cobalt Hexacyanoferrate Film Modified Electrode

The electrocatalysis of dopamine has been studied using a cobalt hexacyanoferrate film (CoHCFe)-modified glassy carbon electrode. Using a rotating disk CoHCFe-modified electrode, the reaction rate constant for dopamine was found to be 3.5 — 105 cm3 mol-1 s-1 at a concentration of 5.0 — 10-5 mol L-1. When a Nafion film is applied to the CoHCFe-modified electrode surface a high selectivity for the determination of dopamine over ascorbic acid was obtained. The analytical curve for dopamine presented linear dependence over the concentration range from 1.2 — 10-5 to 5.0 — 10-4 mol L-1 with a slope of 23.5 mA mol-1 L and a linear correlation coefficient of 0.999. The detection limit of this method was 8.9 — 10-6 mol L-1 and the relative standard deviation for five measurements of 2.5 — 10-4 mol L-1 dopamine was 0.58%.