USE OF CAROTENOIDS IN THE CHARACTERIZATION OF OCTADECYLSILANE BONDED COLUMNS AND MECHANISM OF RETENTION OF CAROTENOIDS ON MONOMERIC AND POLYMERIC STATIONARY PHASES

Different analyses were performed with 29 commercial octadecylsilane bonded columns in HPLC and subcritical fluid chromatography (SbFC) in order to evaluate the characteristics of stationary phases. Two types of test molecules were used, carotenoids and polycyclic aromatic hydrocarbons. The use of the cis-trans isomers of beta-carotene allowed the characterization of the stationary phase (monomeric versus polymeric) and of the carbon content. The separation of luteine and zeaxanthine depends on the nature of the stationary phase and, in addition, allows the evaluation of the extent of accessibility of residual silanol groups. These results, and those of a study on the effect of temperature, allow a better understanding of the separation mechanisms in the retention of planar and non-planar compounds, and emphasize the similarity between HPLC and SbFC.