Identification of basic drugs by the thin-layer chromatographic profiles of their ninhydrin complexes

Fifty-two common basic drugs produce various colours when spotted with ninhydrin on plastic thin-layer plates and heated. When the plate is then developed in a suitable solvent each of the coloured spots separates into a variety of additional coloured spots and patches, the number of which depends on the temperature of heating. The relative intensity and spatial arrangement form a profile that is highly characteristic of the compounds. The formation of such profiles was investigated at 100 and 160 degrees C.