Simultaneous Determination of Dopamine and Uric Acid in the Presence of Ascorbic Acid at the Indole-3-Carboxaldehyde Modified Glassy Carbon Electrode

Indole-3-carboxaldehyde (In3C) molecules were deposited on the glassy carbon (GC) electrode by electrochemical methods in acetonitrile (containing 0.05 M TBATFB). Deposition of In3C was performed by cyclic voltammetry scanning from 0.0 V to 2.0 V at a scan rate of 50 mV s(-1) for 10 cycles in 1 mM In3C solution. The modified surface (In3C-GC) was characterized by cyclic voltammetric response of ferrocene as a redox probe. Elemental composition of the surface was analyzed by X-ray photoelectron spectroscopy (XPS). The applicability of this modified surface was then investigated for the determination of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA) using differential pulse voltammetry. Detection limits were calculated as 1.70 mu M for DA and 4.99 mu M for UA. The linear ranges of the calibration curves were found between 10 mu M -100 mu M for both DA and UA in the presence of 100 mu M AA. The proposed method was applied to the determination of DA and UA in pharmaceutical preparations and urine samples with satisfactory results.