Research Of Capillary Electrochromatography Chiral Monolithic Column Of Modified β-Cyclodextrin

The separation principle of capillary electrochromatography lies in different interaction between samples and stationary phase with special structure. It is important to develop new chiral separation material for widening application of capillary electrochromatography in chiral separation by combiningβ-cyclodextrin with special molecular structure and monolithic material.Theβ-cyclodextrin was derived by substituents with different structure and the derivedβ-cyclodextrins with hydroxypropyl, amidogen, aspartic acid, allylic as substituting groups were obtained. Theseβ-cyclodextrin derivatives were characterized with IR, elemental analysis and thermal analysis respectively. The results showed that these compounds had better stability and water-solubility. The chiral separation performance of these new typeβ-cyclodextrin derivatives has been fully investigated in CEC mode, and the separation mechanism ofβ-cyclodextrin with different substituents were also discussed.A series of new chiral stationary phases (CSPs) were prepared by immobilizingβ-CD derived with aspartic acid,amino,hydroxypropyl andβ-CD to epoxy-group of the glycidyl methacrylate-co-ethylene dimethacrylate (GMA/EDMA) monolithic column. The bonding conditions and modification methods ofβ-cyclodextrin and its derivatives onto modified monolithic column were studied to obtain the best preparation conditions. The functional groups, internal surface morphology, pore size and its distribution of chiral stationary phase were characterized by the fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and mercury porosimetry (MP). In order to optimize the separation conditions of capillary electrochromatography (CEC), the buffer type, concentration, pH value, column temperature and other factors were also studied. The eight amino acids and two chiral drugs were successfully separated by the fabricated four types of chiral monolith column with optimized conditions.In this paper, the allyl-β-cyclodextrin was prepared by the copolymerization of allyl-β-cyclodextrin with GMA. This method increased dosage ofβ-cyclodextrins in stationary phase, and consequently it was propitious to enhance synergy effects of organic molecules and chiral selectivity of monolithic column. 18 kinds of amino acid enantiomers were used separated as reference sample through the CEC mode. The separating property of the monolithic column was investigated systematically. At the same time, the chiral drugs Mexiletine Hydrochloride, Fenfluramine Hydrochloride and chiral pesticides Deltamethrin were also separated and the better effect was obtained by the new type electrochromatography monolithic column.Allyl-β-cyclodextrin and GMA-based-β-cyclodextrin were taken independently as polymerization functional monomer, and the chiral monolithic column of the allyl-β-cyclodextrin polymer and GMA-based-β-cyclodextrin polymer were prepared by one-step bonding method. This method increased the dosage of cyclodextrins in stationary phase, and then it was easy to operate. Consequently the separating ability of the monolithic column was enhanced. In this study, the optimum proportion of the monolithic column was obtained by a large number of experiments. In the selected chromatographic conditions, the enantiomers of rosiglitazone,ketoprofen and guaifenesin were successfully separated.