Lipidomic analysis of glycerolipid and cholesteryl ester autooxidation products

Thin-layer chromatography (TLC), gas chromatography (GC), and liquid chromatography (LC) in combination with mass spectrometry (MS) have been adopted for the isolation and identification of oxolipids and for determining their functionality. TLC provides a rapid separation and access to most oxolipids as intact molecules and has recently been effectively interfaced with time-of-flight (TOF) MS (TOF-MS). GC with flame ionization (FI) (GC/FI) and electron impact (EI) MS (GC/EI-MS) has been extensively utilized in the analysis of isoprostanes and other low-molecular-weight oxolipids, although these methods require derivatization of the analytes. In contrast, LC with ultraviolet (UV) absorption (LC/UV) or evaporate light scattering detection (ELSD) (LC/ELSD) as well as electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) MS (LC/ESI-MS) or LC/APCI-MS has proven to be well suited for the analysis of intact oxolipids and their conjugates without or with minimal derivatization. Nevertheless, kit-based colorimetric and fluorescent procedures continue to serve as sensitive indicators of the presence of hydroperoxides and aldehydes.