Detection of Sugars by Paper Chromatography: the Glycosylamines

Abstract

IN a previous communication¹ we reported that, using a butanol–ethanol–water–ammonia solvent, paper chromatography of diabetic urines and, in certain circumstances, of glucose samples, gave the normal glucose spot together with two extra spots of lower mobility. Subsequent studies of the inter-convertibility of the spots at various pH values have revealed that three spots, possessing the same R_F values and chemical properties as those previously encountered, can be obtained when aqueous solutions containing glucose and ammonium acetate are chromatographed; the substances responsible for the two extra spots are formed when, following common practice, the solution under test is being dried on the paper in a current of warm air. The replacement of ammonium acetate by ammonium salts of other carboxylic acids and by ammonium carbonate led to similar results; in the case of the latter salt it was possible to observe that the compound responsible for the ‘middle-spot’ was formed prior to that responsible for the ‘back-spot’. From a larger-scale experiment in which glucose was heated with aqueous ammonium acetate, a product was isolated which was shown chromatographically to give mainly the ‘back-spot’. This product had a very small optical rotation, and gave the known crystalline α-diglucosylamine octa-acetate² on acetylation; chromatography of the saponified acetate yielded one spot which coincided exactly with the ‘back-spot’. It seemed, therefore, most likely that this product was the equilibrium mixture of the α- and β-diglucosylamines prepared by Brigl and Keppler², a view which was endorsed when these two diglucosylamines were used as reference compounds on chromatograms. We have shown further that glucosylamine, prepared by the method of Ling and Nanji³, is identical chromatographically with the ‘middle-spot’.