Cellulose tris(3,5-dimethylphenylcarbamate)-coated zirconia as a chiral stationary phase for HPLC

In this work we explore the use of microparticulate porous zirconia coated with cellulose tris(3,5-dimethylphenyl-carbamate) (CDMPC) as a support for separation of chiral compounds by HPLC. The surface of zirconia, previously sintered but not rehydroxylated, provides a stable surface for depositing the chiral polymer. Zirconia's surface prior to coating was investigated by diffuse reflectance FT-IR. The spectra indicate the presence of residual hydroxyl groups even after treatment at 750 °C for 5 h. The amount of chiral polymer deposited was systematically varied, and the pore structure of the resulting particles was assessed by nitrogen sorptometry. Dynamic studies of columns packed with these stationary phases were also conducted. We found that columns packed with about 3-4% (w/w) CDMPC coated on 2.5-μm zirconia particles provide an excellent compromise between loading need to impart good chiral recognition ability to the stationary phase and column's chromatographic efficiency. Preliminary results show resolutions higher than 1 for 9 out of 16 racemic mixtures in packed 5-cm columns. The use of shorter columns combined with reduced particle size to provide sufficient resolution has the advantage of decreasing the analysis times and reducing eluent volumes. CDMPC-coated zirconia columns exhibit high stability under normal-phase conditions at relatively high linear velocities.