Fermentation monitoring using a glucose biosensor based on an electrocatalytically bulk-modified epoxy-graphite biocomposite integrated in a flow system

Glucose oxidase (GOD) and metals for the electrocatalytic oxidation of hydrogen peroxide were incorporated in the bulk of a graphite-epoxy composite. An amperometric glucose biosensor based on this biocomposite material made of graphite-epoxy-Au-Pd-GOD was integrated in a flow injection system and used for discrete glucose monitoring of a bioprocess. Stability, reproducibility and flow parameters related to the flow injection system were studied. The analytical system showed a linear response for glucose in the range 10^-5-10 ^-2 mol l^-1 when a potential of 900 mV was applied with respect to an Ag/AgCl electrode. A solution of 0.1 mol l^-1 phosphate and 0.1 mol l^-1 KCl buffered to pH 7 was used as the carrier solution. The reproducibility of the signal was below 5% and the sampling frequency was about 20 samples h^-1. For the final application, the linear working response range was adapted from 1 to 10 g l^-1 of glucose. The results obtained were compared with those obtained with a commercially available glucose sensor and by HPLC.