Separation of linoleic acid oxidation products by micellar electrokinetic capillary chromatography and nonaqueous capillary electrophoresis

In this work the suitability of micellar electrokinetic capillary chromatog raphy (MEKC) and nonaqueous capillary electrophoresis (CE) to the analysis of the primary oxidation products of linoleic acid was studied with uncoate d fused-silica capillaries. The primary autoxidation products of linoleic a cid are the four hydroperoxide isomers 13-hydroperoxy-cis-9, trans-11-octad ecadienoic acid, 13-hydroperoxy-trans-9, trans-11-octadecadienoic acid, 9-h ydroperoxy-trans-10,cis-12-octadecadienoic acid, 9-hydroperoxy-trans-10, tr ans-12-octadecadienoic acid. Addition of a surfactant such as sodium dodecy l sulfate (SDS) or sodium cholate (SC) into the running buffer (20-30 mM 3- (cyclohexylamino)-1-propanesulfonic acid (CAPS) or ammonium acetate, pH 9.5 -11) was required to enhance the water solubility of the sample and selecti vity of the separation. MEKC proved to be a promising new technique for the separation of the primary oxidation products of lipids giving results comp arable to high performance liquid chromatography (HPLC). Partial separation of hydroperoxide isomers was also achieved using nonaqueous CE with methan ol-acetonitrile-sodium cholate as running buffer.