A sensitive electrochemical sensor for direct phoxim detection based on an electrodeposited reduced graphene oxide-gold nanocomposite

The principal objective of this study was to develop a sensitive and selective electrochemical sensor for phoxim detection based on a reduced graphene oxide-gold nanocomposite (RGO-Au) modified grassy carbon electrode (GCE). The proposed sensor was fabricated by pulsed electrodeposition of reduced graphene oxide followed by chronoamperometric deposition of Au nanoparticles, and applied for the electrochemical detection of phoxim. The modified electrode was characterized by SEM, UV-vis spectroscopy, Raman spectroscopy and XRD. The electrocatalytic activity of RGO-Au/GCE towards reduction of phoxim was evaluated using cyclic voltammetry and differential pulse voltammetry. The results showed that the RGO-Au nanocomposite could greatly enhance the electrochemical reduction of phoxim. Under optimal conditions, the reduction peak current was proportional to phoxim concentration over a wide range between 0.01 and 10 μM, and the detection limit was 0.003 μM (S/N = 3). The proposed phoxim biosensor also exhibited excellent stability and reproducibility. In addition, the sensor was successfully employed for determining phoxim in a variety of food samples.