Determination of the catechin contents of bioactive plant extracts using disposable screen-printed carbon electrodes in a batch injection analysis (BIA) system

Abstract This work presents an analytical study of the determination of catechin, extracted from the Brazilian plants Rhizophora mangle , Arrabidaea brachypoda , and Lippia origanoides , using disposable screen-printed carbon electrodes (C-SPE) coupled to a batch injection analysis (BIA) system. Preliminary cyclic voltammetry experiments in acetate buffer solution (pH 4.5) containing catechin revealed reversible redox processes, with anodic and cathodic peak potentials located at ~0.16 V and ~0.10 V vs. Ag/AgCl, respectively, and an irreversible peak at ~0.49 V. Under optimized conditions, the repeatability for direct amperometric determination of catechin, performed at +0.3 V with the C-SPE in the BIA system, using successive injections of 50 μmol L −1 of catechin, was RSD = 1.03% (n = 30). The sampling throughput was 120 injections per hour. The amperometric response showed a linear range from 1 to 150 μmol L −1 (R = 0.999), with detection and quantification limits of 0.021 and 0.070 μmol L −1 , respectively. Application of the proposed methodology for the determination of catechin in extracts of the medicinal plants provided quantitative results similar to those obtained by high performance liquid chromatography (HPLC), at a confidence level of ~95%.