Electrochemical behavior of uric acid at a penicillamine self-assembled gold electrode

The fabrication and electrochemical characteristics of a penicillamine (PCA) self-assembled monolayer modified gold electrode were investigated. The electrode can enhance the electrochemical response of uric acid (UA), and the electrochemical reaction of UA on the PCA electrode has been studied by cyclic voltammetry and differential pulse voltammetry. Some electrochemical parameters, such as diffusion coefficient, standard rate constant, electron transfer coefficient and proton transfer number have been determined for the electrochemical behavior on the PCA self-assembled monolayer electrode. The electrode reaction of UA is an irreversible process, which is controlled by the diffusion of UA with two electrons and two protons transfer at the PCA/Au electrode. In phosphate buffer ( pH 5.0), the peak current is proportional to the concentration of UA in the range of 6.0 x 10(-5) - 7.0 x 10(-4) mol L-1 and 2.0 x 10(-5) - 7.0 x 10(-4) mol L-1 for the cyclic voltammetry and differential pulse voltammetry methods with the detection limits of 5.0 x 10(-6) and 3.0 x 10(-6) mol L-1, respectively. The method can be applied to determine UA concentration in real samples.