Electrochemical behavior of epinephrine at l-cysteine self-assembled monolayers modified gold electrode

Abstract

The electrochemical behaviors of epinephrine (EP) at the l-cysteine self-assembled monolayers modified gold electrode have been studied. The modified electrode shows an excellent electrocatalytic activity for the oxidation of EP and accelerates electron transfer rate. The diffusion coefficient ( D) is 1.48×10 −7 cm 2 s −1. FTIR has shown that cysteine can bind onto the gold surface through the strong sulfur–gold interaction. The electrocatalytic mechanism to EP has been studied. The catalytic current of EP ν s its concentration has a good linear relation in the range of 1.0×10 −7–2.0×10 −6 mol l −1, with the correlation coefficient of 0.9989 by differential pulse voltametric (DPV) response. Detection limit is down to 1.0×10 −8 mol l −1. At a high EP concentration, the relationship between the catalytic current and its concentration exhibits a Michaelis–Menten kinetic mechanism for the electrocatalytic process and the constant K m is about 0.155 mmol l −1. The highest catalytic current I m is 2.72 μA. The modified electrode can be used for the determination of EP in practical injection. The method is simple, quick, sensitive and accurate.