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Characterization of complex lipid mixtures in contaminant exposed JEG-3 cells using liquid chromatography and high-resolution mass spectrometry

Gorrochategui, Eva, Casas, Josefina, Pérez-Albaladejo, Elisabet, Jáuregui, Olga, Porte, Cinta, Lacorte, Sílvia
Environmental science and pollution research international 2014 v.21 no.20 pp. 11907-11916
chloroform, cholesteryl esters, diacylglycerols, formic acid, high performance liquid chromatography, humans, ionization, mass spectrometry, methanol, perfluorocarbons, phosphatidylcholines, phosphatidylethanolamines, sphingomyelins, triacylglycerols, tributyltin
The aim of this study was to develop a method based on ultra high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS) for lipid profiling in human placental choriocarcinoma (JEG-3) cells. Lipids were solid–liquid extracted from JEG-3 cells using a solution of chloroform/methanol (2:1, v/v) in a simple procedure requiring minimal sample alteration. Simultaneous separation of complex lipid mixtures in their major classes was achieved with a reversed-phase (C₈) UHPLC column and a mobile phase containing methanol with 1 mM ammonium formate and 0.2 % formic acid (A)/water with 2 mM ammonium formate and 0.2 % formic acid (B). Lipids were characterized using time-of-flight (TOF) and Orbitrap under full scan and positive electrospray ionization mode with both analyzers. A total of 178 species of lipids, including 37 phosphatidylcholines (PC), 32 plasmalogen PC, 9 lyso PC, 4 lyso plasmalogen PC, 30 triacylglycerols, 22 diacylglycerols, 7 cholesterol esters, 25 phosphatidylethanolamines, and 12 sphingomyelins, were identified using TOF and Orbitrap. The identification of all lipid classes was based on exact mass characterization with an error < 5 ppm. The developed methodology was applied to study lipid alterations in human placental cells against the exposure to perfluorinated chemicals (PFCs) and tributyltin (TBT).