Simultaneous Determination of Metronidazole and Ranitidine Using an Activated GCE Decorated with Electrochemically Reduced Graphene Oxide

An activated glassy carbon electrode (AGCE), modified with reduced graphene oxide (rGO-AGCE), was successfully used to simultaneously determine metronidazole (MT) and ranitidine (RT). The rGO-AGCE was fabricated by electrochemically reducing a graphene oxide (GO)-modified AGCE (GO-AGCE) using linear swipe voltammetry in a neutral KNO₃ solution. A stable electrode surface was formed due to the possible electrostatic interaction between the functional groups of rGO and AGCE, which also helps in catalyzing the reduction reaction of MT and RT. Changes in the surface morphology resulting from the step-by-step modification were evaluated using field emission scanning electron microscopy. Variations in the electrical conductivity of the modified electrode were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) and CV were performed to study the voltametric response of MT and RT at the rGO-AGCE. Amperometry (AMP) and DPV responses were used for quantitative analysis. CV was performed at different scan rates to evaluate the kinetics of the MT and RT reduction process. The charge transfer coefficient and the total number of electrons associated with the reduction process were calculated from scan rate analysis. An excellent recovery of RT and MT was obtained in real sample analysis. Graphical Abstract: [Figure not available: see fulltext.]