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 stu dies and studies of a variety of nonpolar aromatic positional isomers. This material has been compared to polybutadiene-coated zirconia, octadecyl- an d 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 materi al exhibits substantial differences in selectivity toward nonpolar and pola r analytes as compared to other phases, especially with respect to polybuta diene-coated zirconia (PBD-ZrO2). On PS-ZrO2, polynuclear aromatic hydrocar bons (PAHs) are retained much more than are alkylbenzenes, whereas on PBD-Z rO2 the opposite is observed. In addition, PS-ZrO2 has much greater selecti vity than does PBD-ZrO2 for the separation of structural isomers which diff er in the position of phenyl groups. In general, even though the carbon con tent of PS-ZrO2 is much lower than that of conventional reversed-phase mate rials, such as octadecyl-bonded silica (C18-SiO2), polar analytes exhibit s ufficient retention and differential selectivity on PS-ZrO2 that resolution comparable to that on C18-SiO2 can be obtained but with substantially impr oved analysis times.