Micro-scale determination of glucose by capillary flow injection with an immobilized enzyme reactor

Capillary flow injection was combined with an immobilized enzyme reactor to determine glucose in various juice and soft drink samples. Glucose oxidase was successfully immobilized onto open tubular capillary reactors by covalent bonding. The glucose oxidase catalyzed oxidation of glucose to gluconic acid and hydrogen peroxide was coupled with the Trinder reaction in which the hydrogen peroxide reacts to form a quinoneimine dye. The dye produce was monitored spectrophotometrically. Quantitative determinations showed improved sensitivity and reproducibility over determinations using conventional flow injection and glucose oxidase immobilized in a single bead string reactor. The use of capillary flow injection reduced reagent consumption to 320 mu l/h, only 1.4% of that consumed with conventional flow injection. (C) 1999 Elsevier Science B.V. All rights reserved.