Electrocatalytic oxidation of dopamine at sol-gel carbon composite electrode chemically modified with copper hexacyanoferrate

An organic-inorganic composite electrode was prepared by the sol-gel method. For this purpose the carbon composite electrode (CCE) was modified with copper hexacyanoferrate (CuHCF). The CuHCF-CCE was prepared by two methods. In one method CCE was prepared in one step and in another method the electrode was prepared in a two-step process. The electrochemical behavior of the CuHCF modified electrode was studied by cyclic voltammetry; the modified electrode shows a pair of peaks with a surface-confined characteristic in a 0.1 M phosphate buffer (pH 7) with K+ cation, as a supporting electrolyte. The CuHCF-CCE showed electrocatalytic activity toward oxidation of Dopamine (DA). The kinetics of the catalytic reaction was investigated by using chronoamperometry. The average value of the rate constant for catalytic reaction and the diffusion coefficient were calculated. At a 0.85 V potential under hydrodynamic conditions (stirred solution), the oxidation Current is proportional to the dopamine concentration, and the calibration plot was linear over the concentration range of 5-85 mu M.