Catalytic oxidation of dopamine at a microdisk platinum electrode modified by electrodeposition of nickel hexacyanoferrate and Nafion(R)

A chemically modified microelectrode has been prepared successfully by means of electrodepositing nickel hexacyanoferrate(II-III) on a microdisk platinum electrode. This modified electrode could catalyze the oxidation of dopamine and, moreover, eliminate the electrode poisoning caused by the electrochemical polymerization of dopamine at the bare platinum electrode. However, the oxidation of ascorbic acid could also be catalyzed at this modified electrode, thus interfering with the electrochemical response of dopamine. When the modified electrode was further covered with Nafion(R) membrane, the interference could be erased. The catalytic currents increased linearly with the concentration of dopamine in the range of 1.0 X 10(-4) to 1.5 X 10(-2) M. Such a microdisk modified platinum electrode could be used for the determination of dopamine. In addition, the reaction rate constant of dopamine at the modified electrode was evaluated by using a rotating disk electrode.