Analysis of oleate,linoleate and linolenate hydroperoxides in oxidized ester mixtures

The hydroperoxides in oxidized mixtures of methyl oleate, linoleate and linolenate were analyzed by reducing the hydroperoxides to the corresponding hydroxyesters and separating the hydroxyesters from the unoxidized esters by thin layer chromatography (TLC). The hydroxyesters from linolenate were separated from the other hydroxyesters by TLC on silver ion plates. The hydroxyesters were converted to TMS-hydroxy derivatives. The TMS-hydroxyoleate and TMS-hydroxylinoleate were separated by gas chromatography (GC), and all the TMS-derivatives were quantified by GC. The relative rates of oxidation of methyl oleate, linoleate and linolenate in mixtures were ca. 1∶10.3∶21.6. The hydroperoxides formed in the oxidation of soybean and olive oils were similar before and after randomization and similar to corresponding methyl ester mixtures. Journal Paper No. J-9657 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Project 2143.