Preparation Of Novel Hybrid Monoliths And Their Application In Separation And Analysis

Organic-silica hybrid monolith compromises some merits of silica monoliths and organic polymer monoliths,which is the fastest developing chromatographic stationary phase at present.However,the synthesized process of hybrid monoliths is tedious and time-consuming.To circumvent this problem,we developed novel methods for rapid preparation of hybrid monoliths based on photo-initiated mode and hierarchically porous hybrid monoliths(HPHM).Meanwhile,the application of hybrid monoliths in chromatography separation and sample treatment was broadened.A novel "one-pot" approach was developed for preparation of hybrid monoliths via photo-initiated thiol-acrylate polymerization with acrylopropyl polyhedral oligomertic silsesquioxane(acryl-POSS)as crosslinker and a mono-thiol monomer(1-octadecanethiol,ODT)as organic functional monomer.In the reaction process of polymerization,acryl-POSS not only homopolymerizes,but also couples with the mono-thiol monomer.Meanwhile,the major obstacle of oxygen inhibition is essentially eliminated and it takes only several minutes to complete polymerization.The resulting POSS-based hybrid monoliths owned homogeneous framework structure and exhibited good permeability.The column efficiencies for alkylbenzenes on the optimized hybrid monoliths could reach to 60,000?73,500 N/m in capillary liquid chromatography(cLC),which aslo revealed a retention-independent efficient performance in the isocratic elution.In order to further broaden the applications of hybrid monoliths prepared with acryl-POSS,we prepared POSS-based hybrid monoliths via photo-initiated free radical polymerization of acryl-POSS as crosslinker,1H,1H,7H-dodecafluoroheptyl acrylate(DFHA)and propargyl acrylate(PA)as functional monomers.Fluorobenzenes could well be separated on the prepared POSS-DFHA hybrid monoliths,and the column efficiencies could reach to 51,900?76,000 N/m in cLC.Meanwhile,an approach to integrate nanoelectrospray ionization(ESI)emitter with POSS-DFHA hybrid monoliths was developed for quantitative determination of perfluoroalkyl acids(PFAs)in cLC-ESI-MS/MS.Due to the existence of alkynyl group in the prepared POSS-PA hybrid monoliths,ODT and sodium 3-mercapto-l-propanesulfonate(MPS)could be successfully bonded on the surfaces of hybrid monoliths via photo-initiated thiol-yne click reaction.The obtained hybrid monoliths were further successfully applied for two-dimensional separation of complicated biological samples in cLC-MS/MS.Monoliths prepared via free radical polymerization are usually lacking of mesopores or micropores,which also has low surface areas.To address this problem,a novel method to directly was developed to prepare a phosphate-functionalized HPHM,which simultaneously contained micropores,mesopores and macropores.This scheme was based on the copolymerization of octavinyloctasilsesquioxane(vinylPOSS)and vinylphosphonic acid(VPA)as monomers by adding degradable polycaprolactone(PCL)additive.The surface area of optimized HPHM could reach to 502 m2/g.After immobilizing Ti4+ on HPHM,the prepared immobilized metal affinity chromatography(IMAC)HPHM exhibited fast adsorption rate for pyridocal 5'-phosphate,and the adsorption capacity could reach to 63.6 mg/g.Moreover,the Ti4+-IMAC HPHMs were successfully applied to enrich low-abundance phosphopeptides from ?-casein digests,human serum and HeLa digests,and the enrichment specificity was higher than 97.0%.In order to expand the application of hybrid monoliths in enrichment of phosphopeptides,phosphonate-containing hybrid monoliths were prepared via sol-gel chemistry by using tetraethyl orthosilicate(TEOS)and diethylphosphatoethyltriethoxy(DPTS)as precursors.After treating with concentrated HCl,phosphonate group was acidified to phosphonic acid.The surface area of prepared phosphate-containing hybrid monoliths which possessed macropores(pore size,1?3 ?m)could reach 1170 m2/g.After immobilizing Ti4+ on phosphate-containing hybrid monoliths,the prepared Ti4+-IMAC hybrid monoliths exhibited high adsorption capacity for pyridocal 5'-phosphate,which could reach to 77.2 mg/g.Finally,the prepared Ti4+-IMAC hybrid monoliths were applied to enrich phosphopeptides from HeLa digests,and about 2000 unique phosphopeptides could be identified with the specificity as high as 91.0%.