Glucose determination using a flow system with enzyme reactor and application to analysis of glucose content in beverages

Glucose was determined using an apparatus containing an enzyme reactor in a flow line. The enzymes used fur glucose assay were hexokinase and glucose-6-phosphate dehydrogenase. NADH formed by enzymatic reactions was fluorometrically detected. The optimal concentrations of ATP and NAD(+) in the carrier were determined. Of the buffers examined for use as a carrier medium, triethanolamine buffer was found to be the most favorable and the optimal pH of this buffer was pH 7.0. Under these optimal conditions, the calibration curve for glucose was linear in the range of 2.0-200 mu M (r = 0.999). Detection limit was 1.7 mu M (S/N = 3). This method was applied to the analysis of glucose in several beverages. Glucose content determined by the present method agreed with that determined by a commercially available test-kit method. The methods for the preparation of immobilized enzymes were examined to retain the activities of enzymes.