Study On The Preparation, Enantioseparation And Retention Mechanism Of Cyclodextrin Bonded Chiral Stationary Phases

Following aspects were represented in this study:1. The importance of chiral separation, the main chiral chromatographic separation techniques and the recent development of cyclodextrin-based chiral stationary phases were briefly discussed.2. The synthesis and evaluation ofβ-cyclodextrin (β-CD) bonded chiral stationary phases (CSPs) with 3-glycidoxyproryl-trimethoxysilane (KH-560) or 3-isocyanatopropyltriethoxy- silane (IPTS) for the enantioseparation of various chiral analytes by HPLC were presented. By comparison, the former was deemed to have higher bonded amount, higher enantiosparation ability and better stability.3. A hydroxypropyl-β-cyclodextrin (HP-β-CD) bonded chiral stationary phase (CSP) was prepared. Comparative evaluations of these two CSPs for the enantioseparation of hydrobenzoin, benzoin andα-phenethyl alcohol by HPLC were presented. The effects of buffer composition in the mobile phase on the retention and enantioseparation were investigated. The borate buffer had a significant influence on the retention and enantioseparation of hydrobenzoin. Linear solvent strength (LSS) retention model was used to fit the chromatographic data. Good linearity existed between the common logarithm of retention factor (k) and the volume fraction of organic modifier (φ). Another retention model, stoichiometric displacement theory for retention (SDT-R), was also tried to fit the chromatographic data. The results showed that not only acetonitrile, but also water molecules participated in the displacing process of the solute.4. R-1-Phenylethylcarbamoylatedβ-CD-CSP was prepared from R-1-Phenylethyl isocyanate andβ-cyclodextrin bonded CSP. The obtained CSP was packed by slurrying method. Then enantioseparations of hydrobenzoin, benzoin andα-phenethyl alcohol were evaluated under the reversed mode. The effects of acetonitrile amount and buffer type on the retention and enantioseparation were investigated. Hydrobenzoin obtained baseline separation, and the separation factor could reach 1.214. Benzoin obtained partial enantioseparation, and α-phenethyl alcohol could not be separated wholly. Chiral recognition mechanism was studied with the LSS and SDM-R models. Water molecules and acetonitrile molecules were considered to participate in the displacing process.5. Two 3, 5-dimethylphenyl carbamoylatedβ-cyclodextrin stationary phases were prepared in the different solvents. Then the enantioseparation ability of the CSPs was evaluated under normal-phase or reverse-phase condition by HPLC.