Electrocatalytic oxidation and determination of dopamine in the presence of ascorbic acid and uric acid at a poly (p-nitrobenzenazo resorcinol) modified glassy carbon electrode

A sensitive and selective electrochemical method for the determination of dopamine was developed using a p-nitrobenzenazo resorcinol (NBAR) polymer film modified glassy carbon electrode (GCE). The NBAR polymer film modified electrode shows excellent electrocatalytic activity toward the oxidation of dopamine (DA) in a phosphate buffer solution (pH 4.0). The linear range of 5.0 x 10(-6) to 2.5 x 10(-5) M and a detection limit of 3.0 x 10(-7) M were observed in pH 4.0 phosphate buffer solutions. The interference studies show that the modified electrode exhibits excellent selectivity in the presence of ascorbic acid (AA) and uric acid (UA) with a concentration respectively 30- and 3-times higher than that of DA, respectively. A remarkable improvement in cyclic voltammetric responses to DA, AA and UA (three well-defined voltammetric peaks at potentials around 0.390, 0.195 and 0.559 V for DA, AA and UA, respectively) and a noticeable enhancement of voltammetric sensitivity were observed at the NBAR polymer film modified GCE. This work provides a simple and easy approach to selective detection of dopamine in the presence of ascorbic acid and uric acid. (c) 2006 Elsevier B.V. All rights reserved.