A reagent for the detection of amino acids on thin-layer chromatography plates

Detection or identification of amino acids is most important in protein chemistry as they are monomeric units of proteins and also for the determination of their occurrence in natural products. 4-Hydroxyacetophenone-ninhydrin is able to produce various colours when it reacts with amino acids, whereas ninhydrin itself can only give same purple colour with most of them. The detection limits for amino acids for the proposed spray reagent range between 0.1 and 1.0 mug under cold condition and 0.01 and 0.1 mug after heating.