A specific method for d-galactose quantitative determination: A modification of the d-galactose oxidase assay

After treatment with d-galactose oxidase to form an aldehyde group, d-galactose or 2-acetamido-2-deoxy- d-galactose reacted with indole-hydrochloric acid to give a colored compound having a spectrum very similar to that of d-galacturonic acid, but with a maximum at 500 nm and a shoulder at 480 nm. The reaction is linear between 16.6 and 83 nmol of sugar per mL of final solution. 2-Amino-2-deoxy- d-galactose gave no reaction, even when 5 μmol were used, and 2-deoxy- d- lyxo-hexose did not interfere either.