Selective determination of uric acid in the presence of ascorbic acid at poly( p-aminobenzene sulfonic acid)-modified glassy carbon electrode.

The electrocatalytic behavior of uric acid has been investigated with a glassy carbon electrode modified with p-aminobenzene sulfonic acid through electrochemical polymerization. This resulting electrode shows an excellent electrocatalytic response to uric acid and ascorbic acid, with a peak-to-peak separation of 0.267 V in a 0.1 mol L⁻¹ phosphate buffer solution (PBS) at pH 7.0. These results indicate that the proposed electrode can eliminate the serious interference of ascorbic acid, which coexists with uric acid in body fluids. Differential pulse voltammetry (DPV) was used for detecting uric acid with selectivity and sensitivity. The anodic peak current of uric acid was proportional to its concentration in the range of 1.2 × 10⁻⁷–8.0 × 10⁻⁴ mol L⁻¹, with a detection limit of 4.0 × 10⁻⁸ mol L⁻¹. The proposed method has been applied with satisfactory results to the determination of uric acid in human urine without any pretreatment. [ABSTRACT FROM AUTHOR]