Elution, Partial Separation, and Identification of Lipids Directly from Tissue Slices on Planar Chromatography Media by Desorption Electrospray Ionization Mass Spectrometry

摘要

A method for the examination of intact tissue sections forngangliosides and other lipids using desorption electrospraynionization (DESI) mass spectrometry (MS) is presented.nIn the present work, thin tissue slices (16 μm)ntaken from the rat brain are thaw mounted onto planarnchromatographic media and the lipids are eluted, partiallynseparated, and analyzed directly from the plate by DESIMSnin the negative ion mode. With the lanes scannednparallel to the direction of the chromatographic separationnin the full scan mode, the selected ion current associatednwith ions of separated lipid molecules is plotted in ordernof increasing Rf values. Distinctly different classes of lipidsnare detected using this method, including several gangliosidenspecies (i.e., GQ1, GT1, GD1, and GM1) andnsulfoglycosphingolipids. For the examination of gangliosidesnin the full scan negative ion mode from highperformancenthin-layer chromatography (HPTLC) plates,nthe limit of detection (LOD) was determined to be approximatelyn3 pmol. Tandem mass spectrometry (MS/MS)nusing the linear ion trap was used to confirm the presencenof selected gangliosides and other lipids directly from thenHPTLC plate. DESI-MS/MS revealed the presence of bothnthe GD1a and GD1b isomers. The simplicity of thisnapproach where planar separations are relied upon fornsample preparation and presentation to the MS shouldnallow for the examination of a variety of complex samplesnincluding the rapid examination of foodstuffs, bacteria,nwhole blood, and needle biopsies for cancer diagnostics.