Electrocatalytic:: oxidation of N-acetyl-L-cysteine by acetylferrocene at glassy carbon electrode

The electrochemical kinetics of electrocatalytic oxidation of N-acetyl-L-cysteine (NAC) by acetylferrocene (AFc) at a glassy carbon electrode (GCE) in 0.2 M Na2SO4 aqueous solution has been studied by cyclic voltammetry. Although NAC itself showed a very poor electrochemical response at GCE, the response could be greatly enhanced by using AFc as a mediator, which enables a sensitive determination of the substrate (NAC). The reaction rate constant for catalytic oxidation was evaluated as (4.650 ± 0.05) x 10(3) M-1 s(-1) by chronoamperometry. Experimental conditions, which maximize the current efficiency of the electrocatalytic oxidation, such as pH and the concentration of the catalyst (AFc) and the substrate (NAC), were also investigated. The experimental results of electrochemical kinetics of NAC oxidation on GCE in the presence of AFc support the reaction mechanism proposed, the rate deterraining step assumed in schemes and the kinetic equation described in this work which can be used for a sensitive determination of NAC, and also open an avenue for using AFc as a mediator in electrochemical determination. © 2005 Elsevier B.V. All rights reserved.