A highly sensitive determination of sulfite using a glassy carbon electrode modified with gold nanoparticles-reduced graphene oxide nano-composites

Abstract A gold nanoparticles-reduced graphene oxide composite (AuNPs-rGO) was synthesized by chemical co-reduction strategy using ethylene glycol (EG) as a reducing agent. The structure and composition of this AuNPs-rGO composite were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), as well as the transmission electron microscope (TEM) techniques. Moreover, a glassy carbon electrode (GCE) was modified with this AuNPs-rGO composite by dropping method. The electrochemical behavior and the electrocatalytic activity of this AuNPs-rGO/GCE electrode for the oxidation of sulfite were also investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The results showed that this AuNPs-rGO/GCE exhibited high electrochemical activity for the oxidation of sulfite under the synergistic action of AuNPs and rGO. In 0.10 mol L − 1 H 2 SO 4 , the linear range for the determination of sulfite by amperometry at 0.40 V vs SCE was 2.0 × 10 − 7  − 2.3 × 10 − 3  mol L − 1 ( r 2  = 0.995 6) with a detection limit of 4.5 × 10 − 8  mol L − 1 ( S / N  = 3). The sensitivity for the determination of sulfite is 1026.5 μA (mmol L − 1 ) − 1  cm − 2 . At last, the as-prepared modified electrode was successfully used for the determination of sulfite in red wines with satisfactory results.