Submitted to: International Symposium on High Performance Liquid Phase Separations
Publication Type: Abstract Only
Publication Acceptance Date: June 22, 2001
Publication Date: N/A
Technical Abstract: Non-saponifiable lipids (tocol-derived antioxidants and phytosterols) are important minor constituents of vegetable oils. Their compositional distributions are known to have significant bearing on oil quality and stability. In continuation of an earlier study on capillary electro chromatography (CEC)-photodiode array detection of minor oil chemicals in vegetable oils, several bonded stationary phases were evaluated in the context of stationary phase effects on the component resolution and elution behavior of the title compounds. Samples of lipid antioxidants and plant sterols were analyzed by CEC with a capillary column (25 cm x 75 um I.D.) packed with 3-um pentafluoro phenylsilica (PFPS) or 5-um triacontylsilica (C30). In a typical CEC experiment, voltage, temperature, and electrokinetic-injection settings were maintained at 25 kV, 30C, and 10 kV/10s, respectively. CEC with the highly hydrophobic C30 column tended to yield analyte components with high retention values precluding the use of aqueous buffers. Optimization of CEC experimental variables including mixed organic modifiers led to variable degrees of component resolution and retention. Of the mobile phases assessed, non- aqueous methanolic TRIS buffers were found to be the preferred eluents. CEC with the C30 (or PFPS) phase resulted in base-line separations of all components of interest. With the exception of a reversal in elution order of dimethyl isomers, elution patterns obtained with both phases were similar. The results were compared with those from CEC with octyl silica columns. CEC separations of selected plant sterols were evaluated. Examples of analyses of quantitation of nonsaponifiable lipids in vegetable oils are presented.