Biosensor for Xanthine with Improved Sensitivity and Detection Limit

An interference-free amperometric biosensor for the quantitative xanthine analysis is described. Xanthine was monitored through the electrochemical reduction of hydrogen peroxide (produced upon its enzyme-catalyzed oxidation) at a constant applied potential of -50 mV (vs. Ag/AgCl). The biosensor was designed on the basis of a graphite electrode modified with microquantities of platinum and palladium (mixed in the ratio 30% Pt : 70% Pd). The analytical performance of the produced biosensor was compared with previously reported results obtained with a different basic transducer (graphite modified with 10% Pt : 90% Pd). The here presented biosensor exhibits operational characteristics, such as electrode sensitivity, linearity range and detection limit much better than the earlier reported.