Electrocatalytic Determination of Sulfite at the Surface of a New Ferrocene Derivative-Modified Carbon Paste Electrode

A chemically modified carbon paste electrode with 2, 7-bis (ferrocenyl ethyl) fluoren-9-one (2, 7-BFEFMCPE) was employed to study the electrocatalytic oxidation of sulfite in aqueous solution using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. It has been found that under optimum condition (pH 8.00) in cyclic voltammetry, the oxidation of sulfite occurred at a potential about 420 mV less positive than that unmodified carbon paste electrode. The kinetic parameters such as electron transfer coefficient, α and catalytic reaction rate constant, K h were also determined using electrochemical approaches. The electrocatalytic oxidation peak current of sulfite shows a linear calibration curve were obtained in the range 8.7×10-5 M - 1.1×10-2 M and 4.0×10-6 M – 4.43×10-4 M of sulfite concentration with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods respectively. The detection limit (2δ) was determined as 5.3×10-6 M and 2.1×10-7 M by CV and DPV methods. This method was also examined as a selective, simple and precise new method for voltammetric determination of sulfite in real sample.