Galactose determination in an automated flow-injection system containing enzyme reactors and an on-line dialyzer

Abstract d -Galactose is oxidized in a reactor containing immobilized galactose oxidase to give hydrogen peroxide, which is determined spectrophotometrically after an oxidative colorforming reaction in a peroxidase reactor. On-line treatment in a dialyzer, a metal-chelate column and a catalase reactor makes the method essentially free from interferences for serum samples, for example. The effect of catalase impurities in the galactose oxidase preparation is illustrated. The linear range for the determination of d -galactose was from 10 μM to 14 mM, and the recovery from spiked serum samples, at low galactose levels, was close to 100%. The sample frequency was 45 h −1 and the sample volume was 160 μl. The sampler, the pump and the valves in the flow systm were controlled by a personal computer which also collected and analyzed the data.