Publication

Abstract : This paper reports a voltammetric sensor for salicylic acid based on graphene-oxide-modified glassy carbon electrode (GO-GCE). Graphene oxide has been synthesized by a modified Hummers method, and shows predominantly hydroxyl, carbonyl, and epoxy groups. The oxidation of salicylic acid has been studied on glassy carbon electrode (GCE) and GO-GCE, and is found to be an irreversible reaction with a peak potential at 0.79–0.82 V (vs. saturated calomel electrode). The prepared GO-GCE has 2.19 times more surface area than bare GCE, and behaves as a reversible redox platform for the ferricyanide system. The increased area of the electrode, along with the interactions with the functional groups on GO, results in higher currents for the oxidation of salicylic acid. Both GCE and GO-GCE show linear increase of peak current with respect to salicylic acid concentration in differential pulse voltammetry (DPV) studies. The glassy carbon electrode exhibits a linear range of 25 to 1400 μM with a sensitivity of 0.321 μA/μM-cm2, while the GO-modified GCE exhibits a wider linear range of 25 to 2250 μM with a higher sensitivity of 0.396μA/μM-cm2 and a detection limit of 10 μM. Interference studies have been conducted with ascorbic acid and uric acid, and clear peak separation is observed.