Preparation Of Cellulose Derivative-based Chiral Stationary Phases For Separation Of Enantiomers

The objective for the thesis is to develop novel methods to prepare chemically bonded cellulose derivative-based chiral stationary phases (CSPs) for separation of enantiomers by high-performance liquid chromatography (HPLC) and capillary eletrochromatography (CEC).Composite chiral stationary phases were prepared based on two different cellulose derivatives co-coated or co-bonded onto silica matrix. The composite CSPs may exhibit intermediate or higher chiral recognition c apablities than those on the two individual phases, thus broadening the application range of a single cellulose-based CSP.A bifunctional reagent of 3-(triethoxysilyl)propyl isocyanate was initially adopted as a spacer reagent to prepare the bonded type of CSPs with non-regioselective and regioselective approaches. The non-regioselective procedures showed great advantage from the view point of rapid preparation, in which the CSPs can be obtained within 24 h. In addition, the bifunctional reagent used here is super to the diisocyanates traditionally adopted because of the elimination of cross-linking between cellulose derivatives,A radical co-polymerization reaction via methacrylates has also been developed to chemically bond cellulose derivatives onto silica matrix used for CSPs. A considerably high column efficiency was observed on the prepared CSPs for HPLC resolution of test enantiomers. The prepared CSPs are very stable with the addition of tetrahydrofuran and chloroform in the mobile phases, which makes it possible to extend application for separation of enantiomers on the bonded type of cellulose derivative-based CSPs.Positively charged CSPs with cellulose derivatives were firstly prepared by chemically immobilized cellulose derivatives onto silica matrices containing diethylenetriaminopropylated groups. Based on the electrostatic expulsion, basic enantiomers could be separated on the positively charged CSPs under neutral or acidic mobile phase condition, which is super to the traditional method performed under basic mobile phase that might shorten the lifetime of the chiral columns.The bonded type of cellulose-based CSPs were successfully applied to CEC enantioseparations under normal mobile phases of hexane/alcohols, which suggests that cellulose derivative-based CSPs have a potential to be used for separation of enantiomers in CEC. A significant gain in column performance of enantiomerseparations was obtained by changing from pressure-driven to electrically-driven migration of the solutes. And also, the electrosmootic flow (EOF) can be improved in various degrees with the introduction of positively charged amino groups onto the surface of the CSP, thus faster analysis could be achieved on the newly prepared CSPs.