COMPARISON OF THE RETENTION CHARACTERISTICS OF AROMATIC AND ALIPHATICREVERSED PHASES FOR HPLC USING LINEAR SOLVATION ENERGY RELATIONSHIPS

The similarities and differences in retention characteristics of aroma tic and aliphatic phases have been elucidated by the use of linear sol vation energy relationships (LSERs). Three aromatic phases and three a liphatic phases were investigated in a series of mobile phases. The re sults of LSERs on a polymer-based aromatic phase, poly(styrene-divinyl benzene) resin (PRP-1) are very different from those on either silica- or zirconia-based aromatic and aliphatic phases. Retention on all aro matic and aliphatic phases except PRP-1 is dominated by two factors: t he solute size and hydrogen bond acceptor basicity, On the other hand, in addition to these two major contributions, retention on PRP-1 is m arkedly influenced by the solute hydrogen bond donor acidity. We belie ve that PRP-1 exhibits a more adsorption-like retention mechanism than do the other phases. With the inorganic oxide-based phases, the aroma tic phases are less retentive than the aliphatic phases but show a lar ger dependence on molecular polarizability. The enhanced polarizabilit y of aromatic phases is the likely cause of some differences in their chromatographic selectivity relative to the aliphatic phases.