Homogeneous Electrocatalytic Oxidation and Voltammetric Determination of L-cysteine by 1,1- Ferrocenedicarboxylic Acid at Glassy Carbon Electrode

The homogeneous electrocatalytic oxidation of l-cysteine by 1,1?-ferrocenedicarboxylic acid (fdc) as a redox mediator was studied in aqueous mediumat the surface of a glassy carbon electrode(gce) using cyclic voltammetry (cv),chronoamperometry and differential pulse voltammetry (dpv) methods. it was foundthat in the presence of fdc at ph 6.0, the mediated oxidation peak current of l-cysteineis maximum and the oxidation overpotential of l-cysteine decreases about 450 mv. thediffusion coefficient of l-cysteine and catalytic reaction rate constant were alsodetermined using chronoamperometry. the experimental results showed that theelectrocatalytic oxidation peak current of l-cysteine is proportional to the concentrationof l-cysteine. the calibration plot for l-cysteine was found to be linear in the ranges of6.0×10–5m–2.0×10–3m and 2.0×10–5m–5.0×10–4m by cv and dpv, respectively. thedetection limits (s/n=3) were determined as 3.6×10–5 m and 9.8×10–6 m using cv anddpv methods, respectively. finally, the proposed voltammetric method was