DETERMINATION OF DEHYDROASCORBIC ACID BY AN ENZYME SENSOR SYSTEM WITHA PARALLEL-FLOW CELL

An ezyme sensor system was developed for the determination of dehydroa scorbic acid and L-ascorbic acid. The system was constructed from a pa rallel flow cell separated by a dialysis membrane, an immobilized asco rbate oxidase membrane, coupled to a Clark-type oxygen electrode, and L-cysteine, which was present as a reductant. The method is based on t he reduction of dehydroascorbic acid to L-ascorbic acid with L-cystein e in a parallel flow cell. One assay for dehydroascorbic acid could be completed within 8 min. Linear calibratin curves for dehydroascorbic acid and L-ascorbic and were observed in the range of 20 mM-100 mM and 2 mM-20 mM, respectively.