Separation of trans/cis α- and β-carotenes by supercritical fluid chromatography : II. Effect of the type of octadecyl-bonded stationary phase on retention and selectivity of carotenes

Described in this paper are the effects of the type of bonding (monomeric versus arborescent-polymeric) of 22 octadecyl-bonded phases and of carbon loading on the separation of cis and trans isomers of α-and β-carotenes. Only arborescent-polymeric phases afforded the separation of cis and trans isomers, regardless of the degree of carbon loading. Incomplete separation of the α- and β-carotenes is obtained if the capacity factor for α-carotene is below 6. Also described is a method for estimating the void volume in supercritical fluid chromatography, derived from the two-solvent weight-difference method used in high-performance liquid chromatography. The porosity values are in good agreement with those reported in the literature.