DETERMINATION OF SALICYLATE IN BEVERAGES AND COSMETICS BY USE OF AN AMPEROMETRIC BIOSENSOR

A fast and selective enzymatic method for the determination of salicyl ate in beverages and cosmetics has been developed. The enzyme salicyla te hydroxylase was immobilised covalently onto a glassy carbon working electrode of a wall-jet cell coupled with a flow-injection analysis s ystem. The salicylate is enzymatically converted to catechol, which ca n be detected amperometrically on the glassy carbon electrode at +0.45 V. The response of the biosensor is linearly proportional to the conc entration of salicylate between 725 nmol/l and 700 mu mol/l. A high sa mple throughput (60 h(-1)) is possible, and the biosensor is stable fo r more than three months. Sample pretreatment for beverages and hair l otions is easy and fast. For creams, an extraction of salicylate is ne cessary. Relative standard deviations are less than 5.5% and the recov eries are of the commercially between 95 and 105%.