Electrochemical Behavior and Voltammetric Determination of Quercetin in Foods by Graphene Nanosheets Modified Electrode

Quercetin belongs to the flavonol family. It is most abundant among the flavonoid molecules. A method was developed for quantification of quercetin in apple and onion using differential pulse voltammetry at graphene nanosheets modified glassy carbon electrode (GNs/GCE) and UV spectrophotometry as reference method. Interest graphene centers on its excellent mechanical, electrical, thermal and optical properties, it’s very high specific surface area, and our ability to influence these properties through chemical functionalization. The electrochemical behavior of quercetin at the GNs/GCE was investigated, and the results indicated that the electrode reaction was controlled by adsorption. The anodic peak current almost stops increasing after 260 s accumulation. This indicates that the accumulation of quercetin at the electrode surface nearly reaches a saturation state after 260 s. The accumulation potential was analyzed between -0.6 and 0.3 V, a maximum peak was achieved at 0.2 V. Under the optimal conditions, the peak currents of DPV increased linearly with the quercetin concentration in the range from 0.006 to 10 μM and 10 to 100 μM with limit of detection 3.9 nM. The proposed method was successfully applied in the detection of quercetin in foods.