Electrochemical sensor for sulfite determination based on iron hexacyanoferrate film modified electrodes

The development of a sulfite sensor and its application to wine analysis is described. The method for the determination of sulfite is based on the use of glassy carbon electrodes modified with films of Prussian Blue [iron(III,II) hexacyanoferrate(II,III)]. The resulting modified electrodes exhibit a reversible redox response ascribed to the oxidation/reduction of iron atoms present in the electrodeposited film. These films have a potent and persistent electrocatalytic activity towards the oxidation of sulfite with a detection limit of 80 μM and a good linear relationship (0.999) between the catalytic current and sulfite concentrations. According to these results, the described modified electrodes have been used as sensors for the determination of sulfite in various types of wine samples and the results obtained are in agreement with those obtained by the standard iodometric method.