Separation of geometrical carotenoid isomers in biological extracts using a polymeric C-30 column in reversed-phase liquid chromatography

Application of a polymeric C-30 reversed-phase (RP) liquid chromatography (LC) column for separations of geometrical carotenoid isomers extracted from biological sources is demonstrated. The relative retention characteristics of all-trans carotenoid standards on the C-30 column is also shown under isocratic conditions. Carotenoids were extracted from human serum, raw and thermally processed carrots, a Dunaliella algae-derived preparation of beta-carotene, and a poultry feed supplement containing marigold carotenoids. From extracts of plant and algal origin, geometrical isomers of beta-carotene (all-trans, 15-cis, 13-cis, and 9-cis), alpha-carotene (all-trans, 13-cis, 13'-cis, and g-cis), and lutein (all-trans, 13-cis, 13'-cis, 9-cis, and 9'-cis) were separated and tentatively identified, some of which were previously unresolved on other RPLC columns. Chromatography of serum carotenoid fractions resolved the prominent all-trans carotenoids and separated geometrical isomers of lutein, beta-carotene, and lycopene (11 cis-lycopenes). Absolute recoveries of alpha-carotene and beta-carotene from the C-30 column were 64 and 52% in the LC mobile phase and 89 and 88% when 0.1% (v/v) triethylamine (TEA) was added to the mobile phase, respectively. TEA-mediated enhancements in recovery of 21-55% were observed for several other carotenoids.