A new amperometric bienzymatic biosensor for gluconic acid based on the coimmobilization of gluconokinase (EC 18.104.22.168) and phosphogluconate dehydrogenase (EC 22.214.171.124) by polysulfone membrane entrapment onto the surface of a graphite-epoxy composite is reported. This biosensor represents an alternative to gluconate dehydrogenase (EC 126.96.36.199) based methods, which is no longer commercially available. Measurements were done at an applied potential of +0.800 V, room temperature and phosphate buffer pH 7.50; obtaining a linear response range for gluconic acid extended from 7.0 × 10-6 to 2.5 × 10-4 M. Constructed biosensors showed good reproducibility for calibrations using different electrodes (RSD of 1.74%). Finally, biosensor was applied to real wine samples, and the results obtained were validated by comparison with those provided by a reference laboratory. Good correlation was found when the biosensor results were plotted vs. the reference values (slope = 1.03 ± 0.04, intercept = 0.01 ± 0.02, r 2 = 0.995). © 2011 Elsevier B.V.
- Amperometric biosensor
- Gluconic acid