ANOMALOUS BEHAVIOR OF LYCOPENE BY HPLC ON CYANO-AMINO POLAR PHASE

By reversed phase HPLC the highly pure lycopene produces only one peak , that corresponds to the all-trans polyunsaturated system, Commercial standards, however, show generally two peaks that correspond to the m olecule in all-trans configuration (about 90%) and probably to its 13- cis geometrical isomer (about 10%), respectively, independent of the s olvent used to inject the sample. An anomalous HPLC behaviour was obse rved by analysing a commercial sample of lycopene by normal-phase HPLC . In this case the chromatogram showed different profiles depending on the solvent used to prepare the solution to be injected, A relationsh ip between such unusual behaviour and the polarity of the solvent used to dissolve the sample was tentatively found, It is worth emphasizing that in the same HPLC conditions the behaviour of p-carotene does not show the above described phenomenon.