Electrochemical enhancement for flow-amperometric biosensing with an oxidase column

An electrolytic device to enlarge a determination range for biosensing with use of oxidase was fabricated and introduced into a flow-injection amperometric system for l-ascorbate. The biosensing system was assembled with the plunger pump, the electrolytic device, an immobilized laccase column unit, a flow-through type of oxygen electrode and a pen recorder. The electrolytic device enabled to increase dissolved oxygen in the flow streams by electrolysis of the carrier, and thereby, the additional oxygen attributable to electrolysis should be provided to the laccase column and contribute an activation of the laccase reaction. rbate solutions (20 μl) with various concentrations were injected to the system without the electrolytic device and amounts of dissolved oxygen enzymatically consumed were amperometrically monitored. A linear relationship was obtained in a range of 0.25–4.0 mM. On the other hand, a wider linear range of the l-ascorbic acid determination was obtained with use of the electrolytic device (0.25–10.0 mM). Not only laccase but other oxidases, such as ascorbate oxidase and glucose oxidase, were immobilized and introduced into this electrolytic FIA system. Determination ranges of the substrates were also enlarged by using the system. This study indicated that use of the electrolytic device enabled to extend the dynamic range of substrate for the oxidases without any mediators.