DETERMINATION OF THE CARBONYL GROUPS IN OXIDIZED POLYSACCHARIDES BY HYDROXYL-AMMONIUM FORMATE

Oximation method for determination of carbonyl groups in starch and pectic acid oxidized with nitrogen dioxide was modified. As oximation agent hydroxylammonium formiate in 2-methoxyethanol was used. The unconsumed amount of the agent applied in known excess was determined by titration with perchloric acid solution in 2-methoxyethanol. Thymol blue indicator was used. Blank determination is unavoidable. The standard deviation 0.180 and variation coefficient 7.950 were found from 10 determinations of carbonyl groups in sample of starch treated with nitrogen dioxide to high degree of oxidation and standard deviation 0.122 and variation coefficient 6.210 of pectic acid, oxidized to lower degree of oxidation with nitrogen dioxide were found.