RETENTION CHARACTERISTICS OF POLYBUTADIENE-COATED ZIRCONIA AND COMPARISON TO CONVENTIONAL BONDED PHASES

This paper presents a detailed study of retention on a reversed-phase material made by coating polybutadiene (PBD) on porous zirconia. PBD-c oated zirconia particles with six different carbon loads (0.25-5.6% ca rbon by weight) were prepared by evaporatively depositing and cross-li nking PBD on microparticulate porous zirconia, Retention data of a hom ologous series of alkylbenzenes were obtained on the six PBD phases as a function of mobile phase composition in methanol-water and acetonit rile-water mixtures from 20 to 50% (v/v). The results obtained for the phase were compared to those for conventional octadecylsilane (ODS) b onded phases, and the effect of the amount of PBD on retention was stu died in detail. We find that, per amount of bonded phase, the PBD phas e is less retentive than is the ODS phase, but it has comparable hydro phobic selectivity. Furthermore, the PBD phase has about the same sens itivity toward changes in mobile phase composition as does the ODS pha se, and its solute shape selectivity is similar to that of a monomeric ODS phase. Finally, we conclude that retention arises primarily from a partition-like process.