Preparation And Evaluation Of Cyclodextrin Modified Capillary Monolithic Column

With the rapid development of life science,chiral poison and pollution increased seriously.It is necessary to develop more polymer-based as well as organic-silica hybrid monolithic columns with stable structure,excellent chromatographic property and ability of specific recognition.As a new generated chromatographic stationary phase,monolithic column offers several advantages such as faster mass transfer,higher permeability,high selectivity,modifiable pore size,and ease of preparation.Cyclodextrins(CDs)are torch-like naturally occurring cyclic oligosaccharides consisted of several(usually6,7,8)glucose units connected by a-1,4-linkages.This unique structure endows CDs with the ability of forming inclusion complexes with a variety of chiral and achiral compounds,which can be used for chiral selection.In this paper,we prepared two different monolithic stationary phases by a simple "one-pot"method.The prepared monoliths have been used for separation of chiral enantiomers and positional isomers.The main contents are shown as follows:In chapter 1,there is literature review.We introduced the development and applications of novel cyclodextrin chiral stationary phases(CD-CSPs)in liquid chromatography(LC),capillary electrochromatography(CEC),gas chromatography(GC)and supercritical fluid chromatography(SFC).Among them,the polymer-based and organic-silica hybrid monolithic columns which were used for the separation of enantiomers were emphasized.In the end,we summarized this review and put forward the topic selection and scheme design of this paper.In chapter 2,a cyclodextrin(CD)modified urea-formaldehyde resin(OF)monolith has been prepared by using the polycondensation of urea,formaldehydeand and ?-CD through "one-pot" method within 30 min.The composition and the preparation conditions were optimized.Furthermore,the properties of structure,permeability,mechanical stability and reproducibility were also investigated.The coefficient of association R2 between backpressure and flow rate are greater than 0.998.The RSD of rentention time and column efficiency are all below7.40%.Small neutral molecules,phenols and benzoic acids were successfully separated in a mixed-mode interaction on the prepared column.What's more,due to the introduce of CD,the monolith exhibit an ability of chiral recognition on N-carbobenzoxy-DL-aspartic acid and can separate this enantiomers within 12 min.In chapter 3,a CD modified POSS-PEI organic-inorganic hybrid silica hydrophilic column was prepared through "one-pot"cross-linking polymerization by using octa-glycidyl dimethylsilyl grafted polycyclic oligomeric silsesquioxane(POSS-epoxy)as cross-linker while polyethylenimine(PEI)and ?-CD as monomers.The optimal composition,the optimal preparation conditions,the separation mechanism and the performance of the hybrid monolith were discussed.Various analytes were used to evaluate the electrochromatographic characterization on the CD modified poly(POSS-epoxy-PEI)hybrid silica monolithic column such as small neutral molecules,phenols,benzoic acids,nucleobases,as well as positional isomers.And a good retention and high separation efficiency for these compounds were obtained.The colomn effeciency for hydroquinone were up to 82,300plates/m.