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%.