A graphene based electrochemical sensor

Quercetin belongs to the flavonol family and is most abundant among flavonoid molecules. A method was developed for quantification of quercetin in apple and onion using differential pulse voltammetry at graphene modified glassy carbon electrode (GR/GCE) and UV spectrophotometry as a reference method. The electrochemical behavior of quercetin at the GR/GCE was investigated, and results indicated that the electrode reaction was controlled by adsorption. The anodic peak current almost stopped increasing after 280 seconds of accumulation, indicating saturation at the electrode surface. The accumulation potential was analyzed between -0.6 and 0.3 V, achieving a maximum peak at 0.2 V. Under optimal conditions, DPV peak currents increased linearly with quercetin concentrations from 0.006 to 10 and 10 to 100 µmol L-1, exhibiting a detection limit of 3.6 nmol L-1. The proposed method was successfully applied to the detection of quercetin in foods.