Preparation And Application Of Novel Ionic Liquid-silica Hybrid Monolithic Column For Capillary Electrochromatography

In recent years,the research on organic-silica hybrid monolithic column has become one of the frontier fields of capillary monolithic column,since it combines the merits of polymer monolithic column and silica-based monolithic column,such as ease fabrication,wide pH range tolerance,high permeability,good mechanical stability and solvent resistance.Ionic liquid has attracted widespread attention because of their unique properties,such as fine thermostability,good miscibility and designability.It can be used to prepare monolith stationary phase materials with multiple retention mechanism.The development of functionalized hybrid monolithic column is of scientific significance and application prospect.Novel ionic liquids functionalized hybrid monolithic columns were prepared and applied in this thesis,and main contents are listed as following:In chapter 1,the developments of monolithic columns were reviewed.The preparation and application of organic-silica hybrid monolithic capillary column were introduced.The application of ionic liquid in preparation of chromatography stationary phases is demonstrated.Furthermore,the research content and significance of this thesis were briefly stated.In chapter 2,Based on a synergism between thiol-ene click chemistry-based free radical step-by-step polymerization and chain growth reaction,a novel ionic liquid functionalized organic-silica hybrid monolithic capillary column was prepared by using methacryl substituted polyhedral oligomeric silsesquioxane(MA-POSS)as crosslinker,1-mercaptooctane and 1-allyl-3-methyl imidazolium hexafluorophosphate as binary organic monomer.The effects of several factors,including the proportion of reaction mixture,type of initiation on the morphology and column performances of the hybrid monoliths were investigated in detail.The resulted hybrid monolith showed uniform monolithic network,wide pH range tolerance(pH 2-10),good mechanical stability,highly permeability and good batch reproducibility(RSD<6.1%).It exhibits a typical reversed-phase chromatographic behavior with the controllable EOF over a wide pH range,owing to the incorporation of ionic liquid.The prepared monolith can be successfully used for the CEC separation of different types of compounds,including anilines,benzoic acids,alkylbenzenes and phenols.This research provides a facile route for the in-situ polymerization synthesis of ionic liquid functionalized POSS-based hybrid monoliths.In chapter 3,a novel phenylimidazolic organic-silica hybrid monolithic column with stable electroosmotic flow and multiple interaction mechanisms was prepared,and applied for the residue analysis of nitrogen-heterocyclic pesticides in vegetables by pCEC.The retention mechanism of pesticides in the proposed monolithic stationary phase was discussed,and the hydrophobic interaction and electrostatic interaction were prominent.Effects on retention and resolution were systematically evaluated.Under optimum conditions,the method was validated in terms of limit of detection,linearity,accuracy and precision.A reproducible separation of six nitrogen-heterocyclic pesticides was achieved within 10 min,and the linear range was 0.5-100 mg/L and LODs ranged from 0.05 to 0.2 mg/L.The method was applied to the determination of nitrogen-heterocyclic pesticides in vegetables and the recoveries were satisfied.This research provides a novel separation medium and feasible method for the high-efficient analysis of nitrogen-heterocyclic compounds.