Simultaneous amperometric determination of some mono-, di-, and oligosaccharides in flow injection and liquid chromatography using two working enzyme electrodes with different selectivity

A selective dual enzyme electrode system for the monitoring of sugars in flow injection was developed. The working electrodes were based on cellobiose dehydrogenase (CDH) and oligosaccharide dehydrogenase (ODH) ‘wired’ with an osmium-based redox polymer on solid graphite electrodes. In each case the respective enzyme and poly(1-vinylimidazole) (PVI) in which every tenth mer is complexed with osmium (4,4′-dimethylbpy)2Cl, (denoted PVI10dmeOs) were crosslinked with poly(ethylene glycol) diglycidyl ether (PEGDGE). The two enzyme electrodes had distinct but different selectivities and sensitivities towards a number of investigated sugars. The CDH-modified electrodes responded, with relative activities, for cellobiose (100%), lactose (62.5%), maltose (1.2%), glucose (1%) and for higher cellodextrines (Glu3–6) while the ODH electrodes responded to all investigated sugars except d-fructose and the higher cellodextrins with relative activities for d-glucose (100%), cellobiose (60.4%), lactose (47.3%), maltose (40.6%), l-arabinose (26.1%), maltotriose (24.0%), d-galactose (21.9%), d-xylose (13.1%) and d-mannose (8.9%), 1 mM concentrations each. Linear calibration curves for cellobiose were obtained between 25 μM and 3 mM for the CDH- and ODH-modified electrodes with a sensitivity of 7.9 and 1.4 μA mM−1 cm−2, respectively. The dual electrode system was also used as an end column detector for detection of various sugars after their separation in a size-exclusion Chromatographic system.