An approach to analysis of primary amines by a combination of thin-layer chromatography and matrix-assisted laser desorption ionization mass spectrometry in conjunction with post-chromatographic derivatization.

On-spot derivatization has been suggested for the modification of primary amine containing compounds for their analysis by thin-layer chromatography hyphenated with matrix-assisted laser desorption ionization mass spectrometry. The proposed approach was based on post-chromatographic treatment of separated analytes inside the chromatographic zones on the thin-layer chromatography plates by tris(2,6-dimethoxyphenyl)methilium reagent. The derivatives, containing permanent positive charge, reveal exceptionally intense peaks of their cationic moieties and high signal/noise ratio in mass spectra recorded directly from the plates. The method was tested on a series of aliphatic, aromatic, and amine-containing pharmaceuticals.