SIMULTANEOUS AMPEROMETRIC DETERMINATION OF SOME MONOSACCHARIDES, DISACCHARIDES, AND OLIGOSACCHARIDES IN FLOW-INJECTION AND LIQUID-CHROMATOGRAPHY USING 2 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 electrod es. In each case the respective enzyme and poly(1-vinylimidazole) (PVI ) in which every tenth mer is complexed with osmium (4,4'-dimethylbpy) (2)Cl, (denoted PVI(10)dmeOs) were crosslinked with poly(ethylene glyc ol) diglycidyl ether (PEGDGE). The two enzyme electrodes had distinct but different selectivities and sensitivities towards a number of inve stigated sugars. The CDH-modified electrodes responded, with relative activities, for cellobiose (100%), lactose (62.5%), maltose (1.2%), gl ucose (1%) and for higher cellodextrines (Glu(3-6) while the ODH elect rodes responded to all investigated sugars except D-fructose and the h igher cellodextrins with relative activities for D-glucose (100%), cel lobiose (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-man nose (8.9%), 1 mM concentrations each. Linear calibration curves for c ellobiose were obtained between 25 mu M and 3 mM for the CDH- and ODH- modified electrodes with a sensitivity of 7.9 and 1.4 mu A mM(-1) cm(- 2), respectively. The dual electrode system was also used as an end co lumn detector for detection of various sugars after their separation i n a size-exclusion chromatographic system.