Simultaneous determination of ascorbic acid, dopamine and uric acid using poly(4-aminobutyric acid) modified glassy carbon electrode

A polymerized film of 4-aminobutyric acid (P-4-ABA) was prepared on the surface of glassy carbon electrode (GCE) by electropolymerization. Cyclic voltammetry (CV), different pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were used to study the electrochemical properties of the modified electrode. The results indicate that the P-4-ABA film has excellent electrocatalytic activity for the oxidation of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The charge transfer coefficient, α, and the charge transfer rate constant, ks, for electron transfer between 4-ABA and GCE were also calculated as 0.53 and 25.70 ± 0.59 s−1, respectively. Under optimal conditions, the peak separations between AA and DA, DA and UA, AA and UA at modified electrode using DPV method were 208, 136 and 344 mV, respectively. The linear response range for AA, DA and UA were 20.0–800.0 μmol L−1, 5.0–100.0 μmol L−1 and 1.0–80.0 μmol L−1, respectively, and the detection limits were 5.0, 1.0 and 0.5 μmol L−1 (S/N = 3). The modified electrode was successfully used to simultaneously determine AA, DA and UA in human urine sample.