Characterization of new molecular self-assembled monolayers on gold electrode by QCM, EIS, SEM and CV techniques: application for electrocatalytic determination of dopamine in the presence of acetaminophen

Abstract

In this work, molecular self-assembled monolayers (SAM) of 2-(2,3-dihydroxy phenyl) benzothiazole (HPB) on gold electrode are prepared for the first time and described by cyclic voltammetry (CV), electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and quartz crystal microbalance techniques. The redox properties of the modified electrode were investigated by CV at various scan rates, and the apparent charge transfer rate constant (k s) and transfer coefficient (α) were calculated for HPB-SAM/Au. Then, electro oxidation of dopamine (DA) on a HPB-SAM-modified gold electrode has been studied by cyclic voltammetry, chronoamperometry and differential pulse voltammetry (DPV). The mediated oxidation of DA at the modified electrode in CV occurs at a potential of about 180 mV less positive than that of the unmodified gold electrode. The values of electron transfer coefficients (α), catalytic rate constant (k) and diffusion coefficient (D) were calculated for DA, using electrochemical methods. DPV exhibited a linear dynamic range over the concentration range of 0.1–500.0 µM and a detection limit (3 s) of 0.03 µM for DA in pH 7.0.