Submitted to: Liquid Chromatography International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 6/16/1996
Publication Date: N/A
Technical Abstract: Tocopherols are important lipid antioxidants occurring ubiquitously in plants. The lipid antioxidants exist in nature as a complex mixture of 2-methyl-6-chromanol homologues as well as aromatic ring-position isomers each having a three- terpene-unit side chain at the C-2 position. Normal-phase high-performance liquid chromatographic (HPLC) separations of all the tocopherol components have been successful, but require long equilibration times and the use of toxic/volatile solvents. Complete speciation of the natural antioxidant complex by reversed-phase HPLC has been difficult and has not been thoroughly investigated. We report the results of a comprehensive reversed-phase HPLC study on the retention behavior of the title compounds which include alpha-, beta-, gamma-, delta-, and zeta-tocopherols along with their derivatives. Different degrees of component resolution were obtained and were heavily dependent on HPLC variables. Mobile phases employed aqueous systems with acetonitrile and alkanols as organic modifiers. Stationary phases employed alkyl- and aryl-bonded silica columns in addition to hydrocarbonaceous nonsilica-based polymer columns. The latter columns showed unique selectivity for isomeric pairs that have hitherto remained unresolved. Retention and separation characteristics (alpha-, k'- and R-values) were determined and the HPLC data were interpreted in terms of mobile phase-, stationary-, and analyte structure-effects.