FLOW INJECTION AMPEROMETRIC DETERMINATION OF GLUCOSE AND SOME OTHER LOW MOLECULAR WEIGHT SACCHARIDES BASED ON OLIGOSACCHARIDE DEHYDROGENASE MEDIATED BY BENZOQUINONE SYSTEMS

摘要

A comparison has been made on the performance of different oligosaccharide dehydrogenase (ODH) modified electrodes as sensors for the detection of a series of mono-, di-, and oligosaccharides. Monomeric benzoquinone (BQ) or poly(ether amine benzoquinone), PEAQ, as electron transfer mediators were used for the preparation of the electrodes. Four sensor configurations operating in the flow injection mode were studied: (i) ODH adsorbed on the surface of solid graphite with BQ in the now carrier solution; (ii) ODH doped into the bulk of carbon paste electrode with BQ in the now carrier solution; (iii) ODH and BQ doped into the bulk of carbon paste electrode, and (iv) ODH and PEAQ doped into the bulk of carbon paste electrode. All four systems responded to glucose and equal responses were obtained for the alpha- and the beta-anomeric forms. The best sensitivity for glucose was obtained with the solid ODH-modified electrode, which was equal to 1.8 mu A mM(-1) cm(-2). The lowest noise was inherent for carbon paste electrodes with BQ in the paste. For this electrode configuration the responses for 16 sugars were observed. The highest currents were obtained for glucose (100%), lactose (52%), cellobiose (50%), and maltose (49%). For all four sensor systems selectivity profiles were almost the same. [References: 32]