High performance liquid chromatography/electron spin resonance/mass spectrometry (HPLC/ EPR/MS) analyses of radicals is performed for the reaction mixture of 13-hydroperoxy-(9Z,11E)-octadeca-9,11-dienoic acid (13ZE-OOH) with ferrous ions under an aerobic condition, or an anaerobic condition. Radicals are identified from 13ZE-OOH by using high performance liquid chromatography/electron spin resonance spectrometry (HPLC/EPR) and HPLC/EPR/MS. The pentyl radical and isomers of epoxylinoleic acid radicals from 13ZE-OOH are identified under an anaerobic condition and the 7-carboxyheptyl radical and pentyl radical from 13ZE-OOH under an aerobic condition. These results suggest that the formation of the respective radical species depends to a great extent on oxygen concentration in the reaction mixtures.
