Separation of Geometrical Carotenoid Isomers in Biological Extracts Using a Polymeric C₃₀Column 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 β-carotene, and a poultry feed supplement containing marigold carotenoids. From extracts of plant and algal origin, geometrical isomers of β-carotene ( all - trans, 15- cis, 13- cis, and 9- cis ), α-carotene ( all - trans, 13- cis, 13‘- cis, and 9- 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, β-carotene, and lycopene (11 cis -lycopenes). Absolute recoveries of α-carotene and β-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.