Reverse Phase HPLC Separation of Cis-and Trans-Carotenoids and Its Application to β-Carotenes in Food Materials

Four trans-carotenoids, β-carotene, α-carotene, lutein and lycopene, were isomerized with light energy under iodine catalysis and the isomeric mixtures were subjected to reverse phase chromatography on a 5μ VYDAC TP-201 column with mobile phases of methanol-chloroform to separate the major isomers. The amounts and properties of the cis-compounds conformed with separations obtained by others from lime and alumina columns. In each case, the predominant isomers behaved as 13-cis-and 9-cis-isomers, except for the lycopene set which included isomers not previously separated. Use of the system for rapid analysis of 13-cis, 9-cis-and trans-β-carotene in some common food materials was demonstrated. The percentage of cis-isomers in the β-carotene fraction ranged from 1.6 in raw carrot to 29.6 in canned peach.