FLOW-INJECTION ANALYSIS OF GLYCEROL BASED ON OXYGEN-CONSUMPTION USING GLYCEROL DEHYDROGENASE AND NADH OXIDASE

A flow injection analysis system for the determination of glycerol has been developed which incorporates a Clark-type oxygen electrode and an enzyme reactor packed with Sepharose 4B on which glycerol dehydrogenase and NADH oxidase are co-immobilized. The response of the system depended on the concentration of flavine adenine dinucleotide (FAD) added into the carrier solution [0. 1 M glycylglycine-KOH buffer (pH 9.2) containing 30 mM ammonium sulfate]. A linear relationship between the glycerol concentration and the response current in the presence of 60 muM FAD was observed over the 0.1 - 1.5 mM range. The sampling frequency was about 25 samples/h at a flow rate of 0.5 ml/min,and the relative standard deviation was 0.65% at 2.5 mM glycerol level (n=10). Application of this system to commercial white and red wines gave satisfactory results compared with the F-kit method. No sample pretreatment was necessary other than dilution.