Abstract
In the present study, we here report a simple, cost-effective and highly sensitive electrochemical sensor for the selective determination of hydroquinone (HQ) and catechol (CC) using electrochemically pretreated pencil graphite electrode (PPGE). The electrochemical pretreatment of pencil graphite electrode (PGE) was done in phosphate buffer solutions (PBS) and characterized by FT-IR, XRD, SEM and EDX. FT-IR and EDX analysis shows the introduction of oxygen functionalization on the PPGE surface. Further the electrodes were electrochemically characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 0.1M KCl containing K4[Fe(CN)6] as redox probe. Interestingly, The PPGE shows a significant enhancement in the redox peak current of Fe2+/3+, owing to the effective increment in the electroactive surface area at PPGE (1.22cm2) compared with the PGE (0.29cm2). Then the PPGE was utilized for the electrochemical determination of HQ and CC in 0.1M PBS (pH7.0). A reversible electrochemical redox peak for HQ and CC were occurred at PPGE, while PGE doesn't efficiently catalyze the HQ and CC redox reaction under identical experimental conditions. The oxidation current response of HQ and CC at PPGE were increased three and four times respectively compared with the PGE. Further, the DPV analysis displays a wide range of linear responses from 2 to 200μM with a limit of detection (LOD) of 1.17μM for HQ and 1.32μM for CC (S/N=3), respectively. Consequently, the concentration of HQ and CC were successfully determined in the presence of major interferents (10 folds) such as, glucose, ascorbic acid and uric acid. The practical utilization of as-fabricated PPGE was tested in water samples; the obtained results demonstrated that PPGE can be used as a potential candidate for environmental sensor application.