Poly(p-aminobenzene sulfonic acid)-modified glassy carbon electrode for simultaneous detection of dopamine and ascorbic acid

A glassy carbon electrode (GCE) is modified with electropolymerized film of p-aminobenzene sulfonic acid (p-ABSA) in pH 7.0 acetate buffer solution (ABS). Cyclic voltammetry (CV), different pulse voltammetry (DPV) and amperometric curve were used to study the electrochemical properties of the polymer film. The polymer film-modified electrode is used to electrochemically detect dopamine (DA) in the presence of ascorbic acid (AA). Polymer film showed excellent electrocatalytic activity for the oxidation of DA and AA. The DA and AA anodic peak potential values at the modified electrode are 196 and −8 mV, respectively, which can be obtained from DPV recordings. In pH 7.0 ABS, the anodic peak current increases linearly over three concentration intervals of DA, viz., 1.0 × 10−7-1.0 × 10−6, 1.0 × 10−6-1.0 × 10−5 and 1.0 × 10−5-1.0 × 10−4 mol l−1, with the correlation coefficient, 0.9984, 0.9973 and 0.9921, respectively, and the detection limit (S/N = 3) is 2.0 × 10−8 mol l−1. AA has no interference with the determination of DA because of the very distinct attracting interaction between DA cations and the negatively poly(p-ABSA) film. The proposed method exhibits good recovery and reproducibility.