Simultaneous electrochemical determination of uric acid, dopamine, and ascorbic acid at single-walled carbon nanohorn modified glassy carbon electrode.

Single-walled carbon nanohorn modified glassy carbon electrode (SWCNH-modified GCE) was first employed for the simultaneous determination of uric acid (UA), dopamine (DA), and ascorbic acid (AA). The SWCNH-modified GCE displayed excellent electrochemical catalytic activities. The oxidation overpotentials of UA, DA, and AA decrease significantly and their oxidation peak currents increase dramatically at SWCNH-modified GCE. Linear sweep voltammetry (LSV) was used for the simultaneous determination of UA, DA, and AA in their ternary mixture. The peak separations between UA and DA, and DA and AA are large up to 152mV and 221mV, respectively. The calibration curves for UA, DA, and AA were obtained in the range of 0.06-10 microM, 0.2-3.8microM, and 30-400microM, respectively. The detection limits (S/N=3) were 20nM, 60nM, and 5microM for UA, DA, and AA, respectively. The proposed method improved sensitivity for the determination of UA by more than one order of magnitude. The present method was applied to the determination of UA, DA, and AA in urine sample by using standard adding method and the results were satisfactory.