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 c omposite. An amperometric glucose biosensor based on this biocomposite material made of graphite-epoxy-Au-Pd-GOD was integrated in a flow in jection system and used for discrete glucose monitoring of a bioproces s. Stability, reproducibility and flow parameters related to the flow injection system were studied; The analytical system showed a linear r esponse for glucose in the range 10(-5)-10(-2) mol l(-1) when a potent ial of 900 mV was applied with respect to an Ag/AgCl electrode. A solu tion-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 w as 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 w ith those obtained with a commercially available glucose. sensor and b y HPLC.