Simultaneous Detection of Quercetin and Carbendazim in Wine Samples Using Disposable Electrochemical Sensors

Developing low-cost and fast methods for on-site analysis is a long-sought goal of the wine industry, especially to detect excessive concentrations of naturally occurring compounds such as polyphenols and pesticide residues. In this paper, we report on the treatment of screen-printed electrodes, which were capable of detecting the flavonoid quercetin and the pesticide carbendazim simultaneously in wine samples with limits of detection of 51.8x10(-9) mol L(-1)and 60x10(-9) mol L-1, respectively. Furthermore, no significant interference was observed with electroactive substances that can co-exist in wine. We found that the electrochemical pretreatment in Na(2)CO(3)solution eliminated residues and impurities from homemade carbon ink comprising graphite and alkyd resin eventually deposited on the electrodes, which were characterized by combining scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. These findings pave the way for monitoring multiple analytes with screen-printed electrodes, which could be extended to clinical biomarkers.