Monolithic silica columns with covalently attached octaproline chiral selector. Dependence of performance on derivatization degree and comparison with a bead-based analogue.

A monolithic silica gel chromatographic matrix was derivatized repetitively with an octaproline-derived chiral selector (CS). The increasingly derivatized column was tested after each derivatization reaction. The enantioseparation ability, resolution and efficiency were found to depend on the content of CS attained after each reaction. Moreover, enantioselectivity and performance of the column with the highest CS coverage were compared to those of a bead-based chiral stationary phase (CSP) counterpart. The octaproline-derivatized monolithic column demonstrated increased enantioseparation factors, resolution and broader applicability than the particle-based column. Finally, the loading capacity of the CSPs was also examined. The monolithic octaproline-derived column permits the separation of 3-20 times higher molar amounts of the tested analytes (depending on the compound considered) than the particle-based counterpart. The enhanced capabilities of the derivatized monolithic column with respect to that of a bead-based counterpart cannot be explained only on the basis of an increased CS coverage. The involvement of an effect produced by the chromatographic silica support structure in the obtained results is discussed.