Electrochemical behavior of epinephrine at a meso-2,3-dimercaptosuccinic acid self-assembled gold electrode and its analytical application

Meso-2,3-dimercaptosuccinic acid (DMSA) can bind onto the surface of a gold electrode through the strong gold-sulfur interaction. The formation mechanism and electrochemical properties of the DMSA monolayer were studied by electrochemical quartz crystal microbalance, complex impedance analysis, surface enhanced Raman spectroscopy, and cyclic voltammetry. The DMSA-modified gold electrode shows an obvious electrocatalytic activity for the oxidation of epinephrine (EP). There are good linear relationships between peak current and the concentration of EP in the range of 8.0x10(-6) similar to 4.0x10(-3) mol L-1 and 5.0x10(-7) similar to 6.0x10(-3) mol L-1 for the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods with the detection limits of 4.8x10(-7) and 4.7x10(-8) mol L-1 , respectively. The reaction mechanism was primarily discussed. The electrode reaction of EP is an irreversible process with two electrons and two protons at the DMSA-modified gold electrode. The modified electrode was applied to the determination of EP in epinephrine hydrochloride injection samples with satisfactory results.