Simultaneous electroanalysis of dopamine, ascorbic acid and uric acid by poly (vinyl alcohol) covalently modified glassy carbon electrode

A novel covalently modified glassy carbon electrode (GCE) with poly (vinyl alcohol) (PVA) has been fabricated through an electrochemical oxidation procedure and was used to electrochemically detect dopamine (DA), ascorbic acid (AA), uric acid (UA) and their mixture by a differential pulse voltammetry (DPV) method. The modified GCE exhibits potent and persistent electron-mediating behavior followed by well-separated oxidation peaks in cyclic voltammetry (CV) or DPV towards DA, AA and UA with activation overpotentials. For the ternary mixture containing DA, AA and UA, the three compounds can well be separated from each other at a scan rate of 0.50 V s−1 with a potential difference of 140 mV, 140 mV and 280 mV in CV, and 180 mV, 130 mV and 310 mV in DPV between DA and AA, DA and UA, and UA and AA, respectively. The differences are large enough to determine AA, DA and UA individually and simultaneously. The stability of the PVA covalently modified GCE is good up to at least 30 days of continual operation.