Amino-functionalized silica nanoparticles for improved enantiomeric separation in capillary electrophoresis using carboxymethyl-β-cyclodextrin (CM-β-CD) as a chiral selector

We report on the use of amino-modified silica nanoparticles (SiNPs) as an additive to the background electrolyte solution to enhance the chiral selectivity of in capillary electrophoresis that is induced by the presence of a small quantity of carboxymethyl-beta-cyclodextrin (CM-beta-CD). The modified SiNPs were characterized by transmission electron microscopy, elemental analysis and their zeta potential. The method was applied to the separation of four alkaline drugs (ephedrine, chlorpheniramine, propranolol and amlodipine). The addition of the modified SiNPs to the background electrolyte results in a distinct improvement in the separation power, especially when the capillary was pretreated with high concentration of particle suspensions prior to separation. The effects of fractions of modified SiNPs and organic modifier, of the thickness of the SiNP coating layer on the capillary wall were investigated. Under optimum experimental conditions, all the racemates investigated were separated with improved resolution, thus indicating the potential of the method in the field of enantiomeric separation.