Simultaneous Electrochemical Determination of Uric Acid and Ascorbic Acid Using L-Cysteine Self-Assembled Gold Electrode

Abstract

The electrochemical behaviors of uric acid (UA) and ascorbic acid (AA) at the L-cysteine (L-Cys) self-assembled monolayers modified gold electrode (L-Cys/Au electrode) have been studied. The modified electrode shows an excellent electrocatalytical effect on the oxidation of UA and AA by cyclic voltammetry (CV) in 0.1 M phosphate buffer solution (pH 7.0). In differential pulse voltammetric (DPV) measurements, the L-Cys/Au electrode can separate the oxidation peak potentials of UA and AA present in homogeneous solution by about 236 mV though the bare electrode give a single broad response. A successful elimination of the fouling effect by the oxidized product of AA on the response of UA has been achieved at the L-Cys/Au electrode. The detection limit of UA and AA is 2.0 × 10-6 M and 1.1 × 10-5 M, respectively. The proposed method can be used for the determination of UA in urine sample. The method is simple, quick, sensitive and accurate.

Keywords

• L-Cysteine
• Self-assembled monolayers
• Electrochemical determination
• Uric acid