Amperometric and potentiometric determination of catechin as model of polyphenols in wines

Cyclic voltammetry, steady state voltammetry, differential pulse voltammetry are used in order to characterize the electrochemical behavior of catechin on glassy carbon electrodes. Despite adsorption phenomena, it is possible to assay catechin in the concentration range comprised between 1 x 10(-5) and 6 x 10(-4) mol dm(-3). The surface modification by iodide ions and the electrochemical generation of iodine enable to obtain catalytic current and to oxidize catechin by the exchange of one or two electrons. Potentiometric titration of catechin by iodine with two electrodes polarized by a small current intensity is possible but depends strongly on the rate of titrant introduction.