A comparative study of the chromatographic selectivity of polystyrene- coated zirconia and related reversed-phase materials

The chromatographic selectivities of polystyrene-coated zirconia (PS- ZrO₂) have been investigated in detail by means of homologue series retention studies and studies of a variety of nonpolar aromatic positional isomers. This material has been compared to polybutadiene-coated zirconia, octadecyl- and phenyl-bonded silica, and polymer-based reversed phases. In addition, the separations of a wide variety of compound classes on PS-ZrO₂ were compared with those on other aromatic and aliphatic RPLC phases. The PS- ZrO₂ material exhibits substantial differences in selectivity toward nonpolar and polar analytes as compared to other phases, especially with respect to polybutadiene-coated zirconia (PBD-ZrO₂). On PS-ZrO₂, polynuclear aromatic hydrocarbons (PAHs) are retained much more than are alkylbenzenes, whereas on PBD-ZrO₂ the opposite is observed. In addition, PS-ZrO₂ has much greater selectivity than does PBD-ZrO₂ for the separation of structural isomers which differ in the position of phenyl groups. In general, even though the carbon content of PS-ZrO₂ is much lower than that of conventional reversed-phase materials, such as octadecyl-bonded silica (C18-SiO₂), polar analytes exhibit sufficient retention and differential selectivity on PS-ZrO₂ that resolution comparable to that on C18-SiO₂ can be obtained but with substantially improved analysis times.