Simultaneous Differential Pulse Voltammetric Determination of Dopamine and Uric Acid with Polycalconcarboxylic Acid Modified Glassy Carbon Electrode

The modified electrode (PCCA/GCE) was prepared by electrochemical polymerization of calconcarboxylic acid (CCA) on the surface of glassy carbon electrode (GCE). The electrochemical property of the PCCA/GCE was studied by cyclic voltammetry and AC impedance method. It was found that in a PBS of pH 6.0, the oxidation peaks of dopamine (DA) and uric acid (UA) were completely separated, and the potential difference of the oxidation peaks attained to a value of 0.14 V. Based on these findings, a selective method for simultaneous determination of DA and UA by differential pulse voltammetry was proposed. Linear relationships between values of oxidation peak current and concentration of DA and UA were obtained in the ranges of 5.0-43.8 μmol·L-1 and 5.0-50.0 μmol·L-1, with their detection limits of 0.2 μmol·L-1 and 0.5 μmol·L-1 respectively. The proposed method has been used in simultaneous determination of DA and UA in DA injections, giving values of RSD′s (n=5) of 2.43% for DA and 2.35% for UA.