A Study of the Relative Importance of Lipophilic, π–π and Dipole–Dipole Interactions on Cyanopropyl, Phenyl and Alkyl LC Phases Bonded onto the Same Base Silica

Abstract

Cyano (CN), butyl (C4), phenyl and octadecyl (C18) phases prepared from the same base silica gel were chromatographically characterized in order to assess the relative importance of lipophilic, π–π and dipole–dipole interactions in governing retention on these differing phases. Dipole interactions of analytes (possessing dipole moments and low lipophilicity) with CN phases were primarily responsible for the elution order. However, as the analytes’ lipophilicity increased, the lipophilic interaction predominated over the dipole interaction. In comparison, retention on the phenyl phase appeared to be complex, being controlled by a mixture of lipophilic, π–π and dipole–dipole interactions. Retention on the C4 and C18 phases was dictated by the analyte’s lipophilicity and its accessibility into the phase.