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Keywords:

  • Fenton's and Fe2+/O2 systems;
  • unsaturated fatty acids;
  • oligomeric alkenylperoxides;
  • oxidation;
  • mass spectrometry

This study reports the identification of oligomeric alkenylperoxides by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS2), during the oxidation of oleic, linoleic and linolenic acids with Fenton's (Fe2+/H2O2) and Fe2+/O2 systems. The reactions were followed by ferrous oxidation-xylenol orange method together with GC-MS and GC-FID, allowing to observe that both oxidation systems are different in terms of hydroperoxide evolution, probably due to the presence of different intermediate reactive species: perferryl ion and OH· radical responsible for the decomposition of lipid hydroperoxides and formation of new compounds.

The analysis of ESI-MS in the negative mode, obtained after oxidation of each fatty acid, confirmed the presence of the monomeric oxidation products together with other compounds at high mass region above m/z 550. These new ions were attributed to oligomeric structures, identified by the fragmentation pathways observed in the tandem mass spectra. Copyright © 2012 John Wiley & Sons, Ltd.