Preparation And Evaluation Of Polyhedral Oligomeric Silsesquioxanes-based Hybrid Silica Monolithic Columns

Monolithic column is a key parameter of capillary electrochromatography(CEC).Organic-silica hybrid monolithic columns,combining obvious merits of both organic and inorganic monoliths,such as easy preparation,high mechanical strength,wide pH tolerance and good solvent resistance,have attracted extensive attentions in recent years.Based on new functionalized materials,developing novel organic-silica hybrid monolithic columns for developing and improving the techniques of CEC seems to be rather significant.In this thesis,based on polyhedral oligomeric silsesquioxanes(POSS),the profile for developing and electrochromatographic behavior of organic-silica hybrid monolithic columns was studied,and main points are listed as following:In chapter 1,a brief review about the types and general situations of monolithic columns used in capillary eletrochromatography has been indicated.The progress and tendency on preparation and application of organic-silica hybrid monoliths have been focused on,and then the topics and experimental profiles for organic-silica hybrid monoliths have been put forward.In chapter 2,an electroneutral organic-silica hybrid monolithic column was prepared by in-situ copolymerization of 2-hydroxyethyl methacrylate(HEMA)and polyhedral oligomeric silsesquioxane methacryl substituted(POSS-MA).Key parameters including the morphology,mechanical stability,EOF and chromatographic retention mechanisms for the prepared monolith have been investigated.A good mechanical stability and a significant EOF could be obtained by attracting ions from the mobile phase although the surface of the stationary phase is electroneutral.Besides,a typical HILIC retention mechanism was observed when the content of ACN in mobile phase exceeded 70%.Various analytes such as uncharged amides and phenols,and basic nucleic acid bases and nucleosides were separated successfully on the resultant column.In chapter 3,based on the above electroneutral column,a novel hydrophilicorganic-silica hybrid monolithic column with multiple mechanisms was prepared by using VBTA and HEMA as organic monomers.The composition of polymerization mixture was investigated and key parameters such as the morphology,mechanical stability,EOF and chromatographic retention mechanisms were also evaluated for the prepared monolith.The results showed that this organic-silica hybrid monolithic column possessed of a good mechanical stability and multiple mechanisms such as hydrophilic interaction,strong anion exchange interaction and ?-? interaction.Various analytes including uncharged amides and phenols,polycyclic aromatic hydrocarbons,negatively charged benzoic acid compounds and positively charged nucleic acid bases and nucleosides have been separated successfully.In chapter 4,an efficient method for Non-steroidal anti-inflammatory drugs has been developed by CEC with the prepared poly(POSS-MA-co-HEMA-co-VBTA)organic-silica monolithic column.The chromatographic retention behavior of the four NSAIDs(ibuprofen,fenbufen,naproxen and flurbiprofen)has been investigated and the separation conditions were well investigated.Under the optimal conditions,four NSAIDs achieved a baseline separation within 14min.Applied to pigs liver samples with spiked NSAIDs solutions,a good result with the satisfactory recoveries in the range of 80.2?93.0% was obtained.