H OH metabolites OH Article Comprehensive Identification of Glycosphingolipids in Human Plasma Using Hydrophilic Interaction Liquid Chromatography— Electrospray Ionization Mass Spectrometry Karel Hoˇrejší 1,2, Robert Jirásko 1, Michaela Chocholoušková 1, Denise Wolrab 1, David Kahoun 2 and Michal Holˇcapek 1,* 1 Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic;
[email protected] (K.H.);
[email protected] (R.J.);
[email protected] (M.C.);
[email protected] (D.W.) 2 Institute of Chemistry, Faculty of Science, University of South Bohemia in Ceskˇ é Budˇejovice,Branišovská 1760, 370 05 Ceskˇ é Budˇejovice,Czech Republic;
[email protected] * Correspondence:
[email protected]; Tel.: +420-466-037-087 Abstract: Glycosphingolipids (GSL) represent a highly heterogeneous class of lipids with many cellular functions, implicated in a wide spectrum of human diseases. Their isolation, detection, and comprehensive structural analysis is a challenging task due to the structural diversity of GSL molecules. In this work, GSL subclasses are isolated from human plasma using an optimized monophasic ethanol–water solvent system capable to recover a broad range of GSL species. Obtained Citation: Hoˇrejší,K.; Jirásko, R.; deproteinized plasma is subsequently purified and concentrated by C18-based solid-phase extraction Chocholoušková, M.; Wolrab, D.; (SPE). The hydrophilic interaction liquid chromatography coupled to electrospray ionization linear Kahoun, D.; Holˇcapek,M. ion trap tandem mass spectrometry (HILIC-ESI-LIT-MS/MS) is used for GSL analysis in the human Comprehensive Identification of plasma extract. Our results provide an in-depth profiling and structural characterization of glycosph- Glycosphingolipids in Human ingolipid and some phospholipid subclasses identified in the human plasma based on their retention Plasma Using Hydrophilic Interaction times and the interpretation of tandem mass spectra.