Preparation And Characterization Of Novel Hydrophilic Stationary Phase And Its Application In Pressurized Capillary Electrochromatography

Hydrophilic interaction chromatography?HILIC?was proposed in 1990 s by Alpert.It has developed rapidly in the next 20 years.It shows unique advantages and great potential in separation and analysis of strong polarity and hydrophilic compounds.Novel hydrophilic stationary phase was synthesized at the first step in this study.Combined with the pressurized capillary electrochromatography?pCEC?platform,the method of isolating polarity and hydrophilic compounds in an efficient and rapid way was established and modified,which further enriched the application of hydrophilic interaction chromatography.This thesis was divided into six chapters.The first chapter described the basic theory and application of CEC,pCEC,submicron silica particles,HILIC and “thio-ene” click chemistry,and made an overview of electroosmotic flow,the double layer and slip flow in detail.The second chapter investigated the effect of temperature,stirring rate and reaction time on the synthesis of different sizes of silica particles.Reaction conditions were studied and optimized.As a consequence,various sizes of submicron silica particles were synthesized,such as 382±6 nm?421±3 nm?577±6 nm?615±3 nm ? 856±12 nm.These silica particles were uniform,monodisperse and smooth-surfaces under scanning electron microscopy?SEM?.The results indicated that the temperature and stirring rate have significant effects on the particle size by modified St?ber method.Finally,580 nm submicron silica particles were synthesized under the temperature of 26?,stirring rate of 650 r/min and reaction time of 2 h.In addition,when silica particles were synthesized through seeded growth method,the size of silica particles can be significantly increased by prolonging the reaction time of the first step.The third chapter introduced the modification of 800 nm silica particles with cysteine functional groups through “thio-ene” click chemistry.Finally,800 nm Cys-VTMS-SiO₂ were synthesized.The effect of applied voltage,buffer concentration and buffer pH on the separation of phenol,catechol and phloroglucinol was investigated.What's more,the separation of bases and amides were evaluated and compared with the separation results on capillary columns packed with 580 nm Cys-VTMS-SiO₂.The fourth chapter introduced the modification of 580 nm silica particles with cysteine functional groups through “thio-ene” click chemistry.Finally,580 nm Cys-VTMS-SiO₂ particles were synthesized.The hydrophilic mechanism was investigated by the separation of acrylamide and thiourea under different proportion of acetonitrile.On the platform of two separation modes?c LC and pCEC?,the separation performance of capillary column packed with 580 nm Cys-VTMS-SiO₂ was investigated by adjustment of applied voltage,buffer concentration,buffer pH and flow rate.The run to run?n=6?relative standard deviations?RSD?of the retention time of toluene,acrylamide and thiourea were 1.1%,0.8% and 1.0% respectively,and the RSD of peak area were 2.0%,1.1% and 2.0% respectively.The results of day to day?n=3?reproducibility showed that the RSD of retention time were 1.1%,0.9% and 1.0% respectively,and the RSD of peak area were 0.5%,2.0% and 2.0%.The results of batch to batch?n=3?reproducibility indicated that the RSD of retention time were 0.8%,0.2% and 1.2% respectively,and the RSD of peak area were 3.8%,5.0% and 2.0%.It can be seen that the hydrophilic capillary packed column prepared in this paper has good reproducibility in pCEC mode.The difference between batch to batch is small and the success rate is high.The fifth chapter described the modification of 580 nm silica particles with glutathione functional groups through “thio-ene” click chemistry.Finally,580 nm GSH-VTMS-SiO₂ were synthesized.The separation performance of phenolic acidics was investigated by applied voltage,buffer concentration,buffer pH.The sixth chapter summarizes these two kinds of new hydrophilic interaction chromatography methods and looks into the possible research direction in the next step.