Simultaneous determination of ascorbic acid, dopamine, uric acid and xanthine using a nanostructured polymer film modified electrode

This paper describes the simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and xanthine (XN) using an ultrathin electropolymerized film of 2-amino-1,3,4-thiadiazole (p-ATD) modified glassy carbon (GC) electrode in 0.20 M phosphate buffer solution (pH 5 0) Bare GC electrode failed to resolve the voltammetric signals of AA. DA. UA and XN in a mixture. On the other hand, the p-ATD modified electrode separated the voltammetric signals of AA, DA. UA and XN with potential differences of 110,152 and 392 mV between AA-DA, DA-UA and UA-XN, respectively and also enhanced their oxidation peak currents. The modified electrode could sense 5 mu M DA and 10 mu M each UA and XN even in the presence of 200 mu M AA. The oxidation currents were increased from 30 to 300 mu M for AA. 5 to 50 mu M for DA and 10 to 100 mu M for each UA and XN, and the lowest detection limit was found to be 2.01, 0.33, 0.19 and 0.59 mu M for AA, DA, UA and XN, respectively (S/N = 3). The practical application of the present modified electrode was demonstrated by the determination of AA, UA and XN in human urine samples. (C) 2009 Elsevier B V All rights reserved.