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

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Abstract
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.