Today, development of nanotechnology has proved that noble metal nanoparticles show improved catalytic behaviour compared to their bul - improved catalytic performance encourages the scientists to use these nanoparticles in the design of new electrochemical sensors. Sulfite is an anti-oxidant agent widely used as an additive to prevent from oxidation and bacterial growth during the storage of foodstuffs. However, due to its toxic effects, FDA has regulated limitations on the amount of sulfite in foodstuffs [2-3]. Therefore, detection of sulfite is of paramount importance in food quality control process. In this work, electrocatalytic activity of Au nanoparticles towards electrochemical oxidation of sulfite has been investigated. Citrate stabilized Au nanoparticles (AuNPs) has been covered on a low cost and disposable gold DVD electrode via a self-assembly monolayer of L-cysteine (SAM) as linker. The characteristics of AuNPs were investigated using UV-Vis spectroscopy, particle size distribution analysis, zeta potential analysis, and atomic force microscopy. Electrochemical impedance spectroscopy experiments were performed to evaluate the electrochemical behavior of ferri/ferrocyanide solution at the surface of modified electrode. Electrochemical oxidation of sulfite at the surface of the modified electrode was investigated using cyclic voltammetry which showed the decreased oxidation overpotentials and increased current responses of the sulfite compared to the bare Au and gold DVD electrodes. Linear sweep voltammetry was used for quantitative measurements after careful optimization of influential operating conditions such as the amount of AuNPs and the pH of the solution. The calibration curve was linear in the concentration range of 1 × 10-6 M to 5 × 10-3 M of sulfite. The reproducibility of the method defined as RSD% was obtained to be 2%. The analytical applicability of the proposed electrode was demonstrated by determination of sulfite in water and beverages.

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