Combination of graphite-assisted laser desorption/ionization (GALDI) mass spectrometry with thin layer chromatography

Abstract

The potentials of using a graphite matrix for laser desorption/ionization from a thin-layer chromatography (TLC) spot is studied. Using a series of pharmaceutical substances with various functional groups and synthetic N-heterocyclic compounds, it was shown that the simple application of graphite onto TLC spots (outlining contour of the spots and shading the spots with a pencil lead) ensured the efficient desorption/ionization of analytes. In most of cases, the recorded mass spectra revealed only [M + Na]+ and [M + K]+ ion peaks, doublets of which can be used to determine molecular masses. The appearance of [M + H]+ ion peaks in some mass spectra may be due to the presence of mineral acids in the samples. The described approach to the application of the “matrix” onto analyte spots eliminates the danger of spot blurring by a solution or an organic matrix, simplifies the procedure, and shortens the time of sample preparation.