Electrochemical determination of ascorbic acid using sensitive and disposable methylene blue modified pencil graphite electrode.

In the present work, a convenient, efficient and disposable electrochemical sensor has been developed by electropolymerizing methylene blue (PMB) on the surface of a pencil graphite electrode (PGE), which facilitates the electrochemical analysis of an antioxidant l-Ascorbic Acid (AA). The structural characteristics of both the methylene blue modified pencil graphite electrode (PMB/PGE) and the bare pencil graphite electrode (BPGE) have been examined using scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray analysis (EDX). Additionally, the charge transfer behavior has been evaluated using the electron impedance spectroscopy (EIS). The voltammetric response of AA has been examined using different methods, such as differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV). This exploration has been carried out in 0.1 M phosphate buffer solution (PBS) of physiological pH 7.0. The electrochemical sensor PMB/PGE proposed in this study exhibited an improved peak current and a slight negative shift in peak potential for AA compared to bare electrode. The enhancement in peak current at the modified electrode has been attributed to the electrocatalytic characteristics of the modifiers. The limit of detection (LOD) for AA has been determined using the differential pulse voltammetry (DPV), with concentrations ranging from 1.0 μM to 12.0 μM. The calculated LOD value has been found to be 0.15 μM. The selectivity and practicality of the modified electrode has been assessed through the real sample analysis and demonstrating its capability to detect AA in the presence of paracetamol (PA) resulting in satisfactory recovery results. Hence the proposed sensor could be successfully validated for the determination of AA in pharmaceutical sample.