Electrochemical preparation of a reduced graphene oxide/ruthenium oxide modified electrode and its application to the simultaneous determination of serotonin and melatonin

Herein, we report the simultaneous voltammetric determination of serotonin (5-HT) and melatonin (MET) using a reduced graphene oxide/ruthenium oxide (RGO/RuO₂) modified glassy carbon electrode (GCE) for the first time. The as-synthesized RGO/RuO₂ composites were characterized by using a variety of techniques, such as scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray diffraction (XRD), Raman spectroscopy and energy dispersive X-ray spectroscopy (EDX). An enhanced voltammetric oxidation peak was observed for serotonin (5-HT) and melatonin (MET) at RGO/RuO₂ modified GCE. Notably, a sufficient voltammetric peak to peak separation (δE_p) of 290 mV was found between the two species by using differential pulse voltammetry (DPV) analysis. The lower limit of detection (LOD) was calculated as 0.02 μM for 5-HT and 0.18 μM for MET. Moreover, the fabricated sensor was found to exhibit excellent sensitivity, reliability, and durability, surpassing those achievable with other modified electrodes, which may find use in practical industrial applications.