Development of an amperometric enzyme biosensor for the determination of the antioxidant tert-butylhydroxyanisole in a medium of reversed micelles

A biocatalytic scheme, based on the enzyme tyrosinase, has been developed for the determination of the antioxidant tert-butylhydroxyanisole (BHA) in food samples. Reversed micelles formed with ethyl acetate as organic solvent, dioctyl sulfosuccinate (AOT) as emulsifying agent, and phosphate buffer of pH 7.4 as aqueous phase, has been employed as the working medium. The potential applied to the tyrosinase electrode, as well as the temperature of the working reversed micelle, the percentage of aqueous phase, and the pH of the phosphate buffer solution have been optimized. The stability of the enzyme electrode with time has been also evaluated. A very good selectivity has been found with respect to potential interference from other substances commonly present in commercial antioxidant mixtures in food. An Eastman-AQ/enzyme immobilization approach has been employed to improve the stability of the tyrosinase biosensor in reversed micelles flowing streams. A how injection method with amperometric detection for the determination of BHA has been developed and applied to the analysis of this antioxidant in commercial biscuits.