Centri-voltammetry for biosensing systems: biocentri-voltammetric xanthine detection

Centri-voltammetry is a method that combines centrifugation and voltammetry. This method, developed by our group in 2003, yielded promising results when applied to trace analysis of metal ios. We demonstrate here the first application of centri-voltammetry to biosensing systems. A xanthine biosensor was constructed by immobilizing xanthine oxidase on a planar platinum electrode which then was placed at the bottom of a centri-voltammetric cell. The experimental parameters were optimized to give two linear ranges. The first is from 0.1 to 1 mu M, and the second from 5 to 50 mu M. The RSD is 3.4 (n = 5). The biosensor was applied to the determination of xanthine in wine and in urine. Calculated recoveries are 101 +/- 0.61% (n = 3) for wine samples, and 102 +/- 0.556% (n = 3) for urine samples.