Simultaneous determination of ascorbic acid, dopamine, uric acid and tryptophan on gold nanoparticles/overoxidized-polyimidazole composite modified glassy carbon electrode

A novel electrode was developed through electrodepositing gold nanoparticles (GNPs) on overoxidized-polyimidazole (PImox) film modified glassy carbon electrode (GCE). The combination of GNPs and the PImox film endowed the GNPs/PImox/GCE with good biological compatibility, high selectivity and sensitivity and excellent electrochemical catalytic activities towards ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp). In the fourfold co-existence system, the peak separations between AA-DA. DA-UA and UA-Trp were large up to 186, 165 and 285 mV, respectively. The calibration curves for AA, DA and UA were obtained in the range of 210.0-1010.0 mu M, 5.0-268.0 mu M and 6.0-486.0 mu M with detection limits (S/N = 3) of 2.0 mu M, 0.08 mu M and 0.5 mu M, respectively. Two linear calibrations for Trp were obtained over ranges of 3.0-34.0 mu M and 84.0-464.0 mu M with detection limit (S/N = 3) of 0.7 mu M. In addition, the modified electrode was applied to detect AA, DA, UA and Trp in samples using standard addition method with satisfactory results. (C) 2012 Elsevier B.V. All rights reserved.