Preparation and characterization of a poly(methyloctadecylsiloxane) thermally immobilized onto zirconized silica stationary phase for high-performance liquid chromatography

This study describes the preparation and characterization of a HPLC stationary phase (SP) obtained by deposition of poly(methyloctadecylsiloxane) (PMODS) onto the surface of porous zirconized silica particles, followed by thermal immobilization. The SP were characterized using elemental analysis and infrared and 29Si NMR spectroscopies, while their chromatographic behaviors were investigated by separation of selected neutral, acidic and basic compounds of different test mixtures (Engelhardt, SRM 870 and Tanaka tests). The preparation of the metalized support and the thermal immobilization of PMODS onto zirconized silica, optimized by experimental design, produced a SP based on PMODS that showed high values of efficiency (up to 85 000 plates/m) and appropriate asymmetry factors. The presence of zirconium on the surface significantly decreases silica solubility in severe conditions (alkaline mobile phase at pH 10 and high temperature), increasing column lifetime.