Voltammetric determination of uric acid at a fullerene-C60-modified glassy carbon electrode

Glassy carbon electrode modified by microcrystals of fullerene-C-60 mediates the voltammetric determination of uric acid (UA) in the presence of ascorbic acid (AA). Interference of AA was overcome owing to the ability of pretreated fullerene-C-60-modified glassy carbon electrode. Based on its strong catalytic function towards the oxidation of UA and AA, the overlapping voltammetric response of uric acid and ascorbic acid is resolved into two well-defined voltammetric peaks with lowered oxidation potential and enhanced oxidation currents under conditions of both linear sweep voltammetry (LSV) and Osteryoung square-wave voltammetry (OSWV). At pH 7.2, a linear calibration graph is obtained for UA in linear sweep voltammetry over the range from 0.5 mu M to 700 mu M with a correlation coefficient of 0.9904 and a sensitivity of 0.0215 mu A mu M-1. The detection limit (3 sigma) is 0.2 mu M for standard solution. AA in less than four fold excess does not interfere. The sensitivity and detection limit in OSWV were found as 0.0255 mu A mu M-1 and 0.12 mu M, for standard solution respectively. The presence of physiologically common interferents (i.e. adenine, hypoxanthine and xanthine) negligibly affects the response of UA. The fullerene-C-60-modified electrode exhibited a stable, selective and sensitive response to uric acid in the presence of interferents.