| Abstract: | A laccase-based biosensor was developed by specific enzyme adsorption on screen-printed working electrodes of DROPSENS cells, and stabilized with Nafion 0.1% membrane. The electrode was characterized with respect to response time, sensitivity, linear range, detection limit, pH dependence, interferences, and long-term stability. The tested substrates were catechol, rosmarinic acid, caffeic acid, chlorogenic acid, and gallic acid. The optimized biosensor proved the following characteristic performances: the apparent Michaelis Menten calculated considering rosmarinic acid substrate 8.3 × 10?6 mol L?1 (r = 0.995, n = 6); the dynamic range of biosensor response for rosmarinic acid 7 × 10?7 ? 1.5 × 10?6 mol L?1; the detection limit for rosmarinic acid 1.19 × 10?7 mol L?1 (RSD = 1.08%, n = 3). It was noticed that the biosensor reaches systematically 90% to 94.3% from the response obtained by LC-DAD-ESI-MS for real samples. |
