Amperometric mediated carbon paste biosensor based on D-fructose dehydrogenase for the determination of fructose in food analysis

A new mediated amperometric biosensor for fructose is described. The sensor is based on a commercially available D-fructose dehydrogenase. The enzyme is incorporated in a carbon paste matrix containing Os(bpy)(2)Cl-2 as redox mediator that achieves electron transfer at 0.1 V (versus Ag/AgCl) with maximum apparent current densities of 1.2 mA/cm(2). The dependence of the steady-state current on the loading of the mediator and the enzyme, other electrode construction parameters, the operating potential, the pH and the temperature was studied. In the steady-state mode the response current was directly proportional to D-fructose concentration from 0.2 to 20 mM with a detection limit of 35 mu M (signal-to-noise ratio, S/N, 3). In the flow injection analysis mode the response current was directly proportional to D-fructose concentration from 0.5 to 15 mM with a detection limit of 115 mu M (S/N 3). The sensor was used for the determination of fructose in food samples in a flow injection system and validated with a commercial enzyme kit. (C) 1998 Elsevier Science S.A.