Separation of cis/trans isomers of beta-carotene by supercritical fluid chromatography

The aim of this work was to study and improve the separation of beta-carote ne cis/trans isomers in SFC. Five different stationary phases have been tes ted, and their chromatographic behaviour has been determined. Unfortunately , because of the presence of additional isomers in the sample studied, none of the individual columns were able to isolate the four pure main isomers of beta-carotene (9, 13, 15 cis and trans). The coupling of two different m onomeric octadecyl columns was necessary to increase both selectivity and e fficiency. The low viscosities of supercritical mobile phases allowed this column association. The influence of temperature, pressure, nature and modi fier content were also investigated. Finally, with the optimum chromatograp hic conditions, six additional isomers have been separated from the four pr evious ones. One of them has been identified as the 9-9' di-cis beta-carote ne. (C) 1999 Elsevier Science B.V. All rights reserved.