The development of a simple electrochemical method based on molecularly imprinted polymers for the selective determination of caffeic acid in wine

Abstract

Caffeic acid (CA) is an antioxidant of great importance in the food sector, such as wine, where it acts as a marker of wine ageing, as well as in the health sector due to its antioxidant properties and beneficial effects including the prevention of inflammation, cancer, neurodegenerative diseases, and diabetes. A simple and fast electrochemical method was developed for the determination of caffeic acid in a hydroalcoholic medium, based on a molecular imprinted polymer (MIP) in order to highlight the specificity and selectivity of the polymer. A MIP specific to CA was synthesized by the radical polymerization process, using N-phenylacrylamide (N-PAA), tetraethoxysilane (TEOS), ethylene glycol dimerhacrylate (EGDMA) and azobisisobutyronitrile (AIBN) in the presence of CA as template molecule and under thermal conditions (60°C). Screen-printed carbon electrodes were used in the electrochemical measurements without any pre-treatment or modification of their surface, in order to ensure the simplicity of the method. Cyclic voltammograms were applied at a scan rate of 50mV/s, from -0.4 to 0.8 V, and showed that, at pH3, the polymer presented good stability and repeatability regarding CA determination. In addition, it exhibited high selectivity towards CA compared to other interferents with similar structures. Furthermore, the polymer was successfully tested for the detection of CA in wine.