Enantioseparation of basic chiral compounds on a clindamycin phosphate-silica/zirconia hybrid monolith by capillary electrochromatography

An organic-inorganic silica/zirconia hybrid monolithic capillary column was prepared by sol-gel process in a fused-silica capillary by using triethoxysilylpropylcarbamate (TEOSPC) derivative of clindamycin phosphate (CLIP) as a chiral selector. A sol solution consisting of 6 × 10−3 M of polyethylene glycol, 1 M of water, 2 M of acetic acid and 0.04/0.96 ratio of CLIP-TEOSPC/Zr-Bu resulted in homogeneous monolith having well defined through-pores and tightly anchored to the capillary wall. The column was employed for capillary electrochromatographic enantioseparation of eight basic chiral drugs in mobile phases consisting of acetonitrile, methanol and ammonium acetate (AA, as the electrolyte). Effects of the compositions of solvents and electrolyte in the mobile phase, applied voltage and capillary temperature on chiral separation were investigated. The highest resolution values were obtained with mobile phases consisting of 40/60 MeOH/ACN and 100 mM AA (for citalopram, Tröger's base, indapamide, metoprolol, cetirizine and atropine) and 35/65 MeOH/ACN and 100 mM AA (for sertraline and propranolol) using −10 kV applied voltage at 25 °C.