Potential-step coulometry of D-glucose using a novel FAD-dependent glucose dehydrogenase

This paper describes the construction and characterization of a batch-type coulometric system for the detection of D-glucose using a novel FAD-dependent glucose dehydrogenase. In order to overcome the problem of interferents, such as ascorbate and urate, a potential-step method was proposed to separate the electrolysis reactions of interferents and D-glucose by selecting a mediator possessing an appropriate formal potential. The rapid oxidative consumption of the interferents proceeded in the first step, whereas the mediator and glucose remained reduced. In the second step, the mediator was immediately oxidized, and subsequent bioelectrocatalytic oxidation of D-glucose occurred with the aid of aldose 1-epimerase. In this study, potassium octacyanomolybdate (IV) with a formal potential of 0.6 V vs. Ag|AgCl was chosen as a mediator, and the first and second electrolysis potentials were set at 0.4 V and 0.8 V, respectively, by considering the heterogeneous electron-transfer kinetics and the potential window. The background-corrected response in charge corresponded to 99+/-2 % efficiency in terms of the amount of D-glucose.