It was found that glucosamine-HCl reacted with p-nitrobenzaldehyde in pyridinemethanol solution to yield Schiff base and gave a blue color by addition of tetraethylammonium hydroxide solution. This new color reaction is selective for 2-amino-2-deoxy sugars and α-amino carbonyl compounds, such as aminoacetaldehyde, δ-aminolevulinic acid and α-aminoacetophenone. The microdetection methods for 2-amino-2-deoxy sugars and their derivatives were proposed and the reaction mechanism was investigated.