The development of a sulfite biosensor based on the immobilization of sulfite oxidase (SOD) in electrodeposited polytyramine is described. Electropolymerization of polytyramine and simultaneous immobilization of SOD on platinized glassy carbon (GC/Pt) were performed in an aqueous solution of 0.1 M tyramine containing SOD. The sulfite biosensor constructed with five voltammetric sweep cycles showed a sensitive response to sulfite with a linear calibration curve in the concentration range 0.002–0.3 mM sulfite, slope 2.70 µA l mmol–1, and detection limit 0.001 mM sulfite (S/N = 3). Deposited polytyramine enhanced the selectivity of the biosensor by eliminating direct oxidation of sulfite and other interfering agents at the electrode. The biosensor was applied for the determination of sulfite in various types of wine samples, and the results obtained are in agreement with those using an AOAC method.
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