Colour reactions given by sugars and diphenylamine-aniline spray reagents on paper chromatograms

Conditions have been defined in which mixed acidic diphenylamine-aniline sprays give, on paper chromatograms, specific colour reactions with uronic acids, aldoheptoses, methyl pentoses and pentoses. When the reagents are applied as two successive sprays, i.e. diphenylamine followed by aniline, additional specific colour reactions are obtained with (1) all aldohexoses and reducing aldohexose disaccharides (other than those containing a 1,4-link) and (2) with some ketoses. This split reagent is able to distinguish clearly between l-sorbose and d-fructose. The possible reactions involved in the formation of the colours are discussed.