Electrosensing of an alpha-adrenergic agonist psychoactive methyldopa using a sodium bentonite–graphene oxide nanocomposite

In the present report, we describe the preparation of a sodium bentonite–graphene oxide nanocomposite for the electrosensing of methyldopa (MD). The fabricated electrode materials viz., graphene oxide (GO), sodium bentonite–graphene oxide (Bent–GO) and Bent–electroreduced graphene oxide (Bent–ErGO) were characterized using XRD, FTIR, absorption, Raman spectroscopy, FESEM and AFM methods. Bent–GO suspension was prepared by the exfoliation of GO and Bent in water. Bent–GO suspension was drop casted on GCE followed by electrochemical reduction to obtain Bent–ErGO/GCE. The electronic properties of the modified GCEs were evaluated employing CV and electrochemical impedance measurements. The redox response of MD increased significantly with the negative shift in peak potentials with Bent–ErGO/GCE compared to that with bare GCE. Based on the enhanced electrochemical response, chronoamperometric and differential pulse voltammetric (DPV) methods were developed as alternative analytical methods for the assay of MD. Under the optimized conditions, a linear relationship was observed between the peak current and concentration of MD in the range of 1.13–40.6 μM and 0.1–60 μM for chronoamperometric and DPV methods, respectively. Furthermore, the proposed electrochemical sensor was successfully employed for the determination of MD in pharmaceutical formulations.