Study of the retention and selectivity of cholesterol bonded phases with different linkage spacers.

The chromatographic properties of four cholesterol bonded phases with different structures were studied. The columns used were packed with a stationary phase containing a cholesterol molecule attached to the silica surface using different types of linkage molecules. As a basic characteristic of the bonded phases the hydrophobicity and silanol activity (polarity) were investigated. The presence of the polar amino and carboxyl groups in the structure of the bonded ligand strongly influences the polarity of the bonded phase. Columns were compared according to methylene selectivity using a series of benzene homologues and according to their shape and size selectivity using polycyclic aromatic hydrocarbons (PAHs). The measurements were done using MeOH-water and ACN-water mobile phases. The presented results show that the coverage density of the bonded ligands and length of the linkage strongly influence the retention and selectivity of cholesterol bonded phases.