Structural analysis of hydroperoxy- and epoxy-triacylglycerols by liquid chromatography mass spectrometry.
Oxidation of triacylglycerols (TAGs) containing oleic acid leads to the formation of several products. This study characterizes hydroperoxy- and epoxy-TAGs including their regio-isomers. For this purpose, epoxy- and hydroperoxy-TAGs, formed by oxidation of 1,2-dipalmitoyl-3-oleoyl-glycerol (PPO) and 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) under air and 18O2, were analysed by reverse phase liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) using a triple quadrupole mass analyser, in positive ion mode. Post-column infusion of ammonium formiate was used to obtain intense molecular ion adducts. Pure 1,2-dipalmitoyl-3-epoxystearoyl-glycerol (PPEs) and 1,3-dipalmitoyl-2-epoxystearoyl-glycerol (PEsP), synthesized by epoxidation of the corresponding monounsaturated TAGs, were used to confirm MS/MS identification. The use of 18O2 oxidation experiments permitted unambiguous identification of MS/MS fragmentation pathways of both hydroperoxide and epoxy-TAGs. Fragmentation of hydroperoxy-TAGs are very distinct from their epoxy-TAGs homologues and consist of simultaneous losses of hydrogen peroxide (34 a.m.u.) and water (18 a.m.u.).
Giuffrida
Francesca
F
Nestlé Research Center, Vers-chez-les-Blanc, P.O. Box 44, CH-1000 Lausanne 26, Switzerland.
Destaillats
Frédéric
F
Skibsted
Leif H
LH
Dionisi
Fabiola
F
D000388:Air; D002853:Chromatography, Liquid / Q000379:methods; D004852:Epoxy Compounds / Q000737:chemistry; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry; D007536:Isomerism; D013058:Mass Spectrometry / Q000379:methods*; D019301:Oleic Acid / Q000737:chemistry; D010084:Oxidation-Reduction; D013229:Stearic Acids / Q000737:chemistry; D014280:Triglycerides / Q000032:analysis / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D004852:Epoxy Compounds; D005229:Fatty Acids, Monounsaturated; D013229:Stearic Acids; D014280:Triglycerides; D014867:Water; D019301:Oleic Acid; C031183:stearic acid