Separation of isomers of aromatic amines on HPTLC plates impregnated with 18-crown-6

A high-performance thin-layer chromatographic (HPTLC) method, on silica plates impregnated with the crown ether 18-crown-6, has been developed for the isomers of seven amines of azo dyes prohibited under a German ban. Plates were developed successively with two mobile phases, benzene for the first development, to a distance of 7.5 cm, and, after drying, toluene for the second development, to a distance of 7.5 cm. Plates were visualized at λ = 254 nm. Eighteen amines were studied by use of the method. The limit of determination ( X ) and the correlation coefficient in the range X to 5 X are reported for each amine. Synthetic mixtures and dye samples have been resolved and quantified.