Electrochemical determination of catechin, protocatechuic acid, and L-lactic acid based on voltammetric response of ferroceneboronic acid.

An electrochemical technique for the determination of catechin, protocatechuic acid, and L-lactic acid has been developed using ferroceneboronic acid (FBA) as an electrochemical probe. The principle is based on thechanges in voltammograms of FBA associated with selective binding of the analytes to FBA. A cyclic voltammogram and a differential pulse voltammogram (DPV) of FBA were recorded on a glassy carbon electrode in the presence of the analytes. The oxidation or reduction peak currents of FBA were decreased in the presence of the analytes, depending on their concentrations. The DPV measurements provided useful calibration graphs in the concentration range of 0.5-4.0 x 10(-3) M catechin, 0.1-1.2 x 10(-5) M protocatechuic acid, and 0.5-40 x 10(-5) M L-lactic acid. The proposed method was successfully applied to the analysis of catechin in abdominal pain water medicine.