Modification of glassy carbon electrode in basic medium by electrochemical treatment for simultaneous determination of dopamine, ascorbic acid and uric acid

In this paper, a modified glassy carbon electrode was prepared by electrochemical method in basic media (0.5 M NaOH solutions) and was used to electrochemically detect dopamine (DA), ascorbic acid (AA), uric acid (UA) and their mixture by a differential pulse voltammetry (DPV) technique. In this simultaneous detection, the electrochemical potential difference between AA and DA was measured to be 165 mV, while between DA and UA it was 135 mV, and between AA and UA 300 mV. The potential differences were large enough to determine AA, DA, and UA individually and simultaneously. The DPV oxidation peak current was linearly dependent on DA, AA, and UA concentration in the range 3-30 mu M, 25-300 mu M, and 5-70 mu M, with correlation coefficients of 0.994, 0.998, and 0.996, respectively. The limit of detection (S/N = 3) was found to be 2.67, 23.38 and 4.70 mu M for DA, AA and UA. The modified electrode was applied to the determination of DA, AA, and UA in real samples. These results and interference studies showed that the modified electrode possesses the potential for simultaneous determination of DA, AA, and UA. (C) 2012 Elsevier B. V. All rights reserved.