Oxidation and Detergency of Oily Soil. III

To clarify changes in and detergency of oxidized oily soils, oxidized linoleic acid was analyzed by reverse phase high performance liquid chromatography (HPLC) using a UV detector.The oxidized products were separated and their molecular weights determined using liquid chromatography-mass spectrometry (LC-MS). Finally, their molecular structures were estimated.During HPLC, compounds from oxidized linoleic acid having a polarity higher than pure linoleic acid were finely separated using an eluent of acetonitorile and water (8 : 2). Compounds with lower polarity than the pure acid were separated using an eluent of acetonitrile, tetrahydrofuran, and water (6 : 3 : 1).Based on the results of LC-MS, the main products obtained by oxidation were hydroperoxide, hydroxy compounds, a dienone compound, and dimers formed by secondary reactions. By HPLC analysis, retention times of the dimers were shown to be longer, and their polarities, less than that of pure linoleic acid.