Electrochemical study of new self-assembled monolayer of 2-hydroxy-N′1-[(E)-1-(3-methyl-2-thienyl) methylidene] benzohydrazide on gold electrode as an epinephrine sensor element

Abstract

2-Hydroxy-N′1-[(E)-1-(3-methyl-2-thienyl) methylidene] benzohydrazide (HMTMBH) self-assembled monolayer has been fabricated on a bare gold electrode (Au electrode) as a novel sensor for determination of Epinephrine. The characterization of Au HMTMBH self-assembled monolayer modified electrode (HMTMBH SAM-ME) was investigated by cyclic voltammetry and ac impedance spectroscopy using the [Fe(CN)6]−3/−4 redox couple. Initially, cyclic voltammetry was used to investigate the redox properties of this modified electrode at 0.5molL−1 H2SO4 and 0.5molL−1 NaOH solutions. The extent of surface coverage was evaluated as 1.52×10−9molcm−2 based on charged consumed for reductive desorption of the monolayer in the 0.50molL−1NaOH solution. The EIS was used to evaluate pKa of the adsorbed HMTMBH on the gold surface, and a value of 6.5 was obtained for the Au-HMTMBH surface pKa. Cyclic voltammograms on bare Au and the Au-HMTMBH SAM electrodes showed that the kinetic of Epi on the Au-HMTMBH SAMs electrode was more rather quick than that on bare Au electrode and the presence of the HMTMBH at the electrode surface reduces the over potential of Epi oxidation, shifting the potential value by −28mV, respectively. So cyclic voltammetry showed very stable response for Au-HMTMBH electrode towards the Epi oxidation, and excellent anti-fouling property against the oxidation products. Thus, it could find potential application for the determination of Epi.