MWCNT/Graphene Nanocomposite based Electrochemical Sensor for Highly Selective Detection of Gallic Acid in Food Beverages

Abstract

Gallic acid (GL) stands as a significant organic compound present in various natural plants and food beverages. Within this study, a chemical sensor has been devised for monitoring GL levels across a spectrum of beverages such as wine, green tea, and fruit juices. The electrochemical oxidation behavior of GL was noted to follow an irreversible oxidation pattern, for which a proposed electrochemical oxidation mechanism was delineated. Investigation into the impact of supporting electrolyte pH on the electrochemical oxidation behavior was conducted, leading to the selection of pH 6.0 as the optimal condition. Scan rate analysis revealed a linear correlation between the square root of scan rate and peak currents of GL, affirming the diffusion-controlled nature of GL oxidation. Kinetic parameters including diffusion coefficient, heterogeneous rate constant, and charge transfer coefficient were subsequently determined. Employing concentration effects, the limit of detection (LOD) and limit of quantification (LOQ) were computed as 5.39 × 10^-7 M and 1.23 × 10^-6 M, respectively. Assessment of repeatability, reproducibility, and stability of the developed electrode demonstrated its superior performance. Lastly, practical application of the sensor was assessed for the quantitative assessment of GL levels in wine, green tea, and fruit juices