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 × 10(5) cm(3) 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%.