A Combined Cellobiose Oxidase/Glucose Oxidase Biosensor for HPLC Determination On-Line of Glucose and Soluble Cellodextrines

Highly specific biosensors can be prepared by immobilizing flavin-containing oxidases in a redox polymer on an electrode surface. By combining one glucose oxidase and one cellobiose oxidase electrode in a flow cell we have made a sensor for flow-injection analysis, or postcolumn quantification, of glucose, cellobiose, and higher cellodextrines in an HPLC system. Samples of different concentrations of glucose and cellobiose, separately or mixed, were injected into the mobile phase and the current response was recorded simultaneously from both electrodes. The recorded response peak heights could be used for calibration curves. The usable measuring ranges were roughly 50 μM-50 mM for glucose and 5 μM-80 mM for cellobiose. Soluble cellodextrines, Glc1-6, could be separated on a C18 column by isocratic elution and detected by the sensor.