Fabrication of 8-nitroquinoline coated pencil graphite electrode for rutin determination by differential pulse voltammetry in orange juice

In this study, we developed a facile and low-cost method to prepare a modified electrode named 8-NQ/PGE by coating the pencil graphite electrode (PGE) surface with 8-nitroquinoline (8-NQ) molecule. The surface modification process was carried out by electrochemical reduction of 8-NQ on the PGE surface in ethanol solution. The characteristic of the prepared electrode was analyzed through cyclic voltammetry (CV) with redox probes, differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), Fourier transformed infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The method was developed to determine rutin (Ru) with the modified electrode (8-NQ/PGE). The developed electrode showed excellent performance for Ru oxidation in a pH 3.0 Britton Robinson buffer (BR). In this media, linearly increasing anodic peak currents were observed with the concentration of Ru in two wide concentration ranges (i.e., 0.016–0.96 µM and 0.96‒19.73 µM), therein the sensor showed a low detection limit (i.e., 4.14 nM) (3s/m). It displayed good stability and selectivity. Also, it was used successfully for the determination of Ru in orange juice samples.