Preparation Of Novel Monoliths And Their Application In Separation And Enrichment

As a highly efficient separation technique,high performance liquid chromatography(HPLC)generally occupies a very important position in the field of analytical chemistry.In the last twenty years,capillary liquid chromatography(cLC)has developed rapidly.Compared with conventional LC,cLC not only reduces consumption of stationary phase,mobile phase and sample,but improves column efficiency and sensitivity of chromatography separation.As a result,it has become a hot spot in the field of micro/nano-scale separation and analysis.The most common stationary phases in cLC are either packed capillary column or monolithic column.Compared with packed column,capillary monolithic column prepared by in-situ polymerization has been widely used in cLC due to its advantages such as simple preparation process,high permeability and fast separation speed,which has attracted great attention in the field of separation and analysis.At present,the latest development of monolithic column mainly focuses on three aspects:(1)improving column efficiency,(2)adjusting selectivity and(3)application.Aiming at the selectivity and application of monolithic materials,this paper prepared two kinds of monolithic materials by using different methods such as changing monomers and post-modification,and applied them in chromatography separation and sample preparation.At first,acrylopropyl polyoctahedral silsesquioxane(acryl-POSS)and 3-(triallyl silyl)propyl acrylate(TAPA)were chosen as precursors to synthesize poly(POSS-co-TAPA)monolithic column(monolith I)via photo-initiated free-radical polymerization within 10 min.Both penicillamine and 1-octadecanethiol(ODT)were then introduced to modify the prepared poly(POSS-co-TAPA)column via photo-initiated thiol-ene click reaction within 20 min.Finally,three resulting monolithic columns were applied in cLC,and several kinds of mixtures of alkylbenzenes,phenolic,anilines and antibiotics mixtures were efficiently separated.These mixtures were baseline-separated on the monolith modified with penicillamine(monolith II),exhibiting better selectivity than both pristine monolith ? and that modified with ODT(monolith ?).Additionally,the penicillamine-modified monoliths were further used for separation of tryptic digest of Hela cells by cLC-MS/MS,and 5071 unique peptides mapped to 2442 proteins were identified from Hela cells tryptic digest.These results demonstrated that these POSS-containing columns exhibited great separation ability for complex samples.In addition,by introducing triglycidyl isocyanurate(TGIC)and 1,4,7,10-tetraazacyclododecane(cyclen)as precursors,polyethylene glycol 200(PEG200)and acetonitrile(ACN)as porogenic solvents,a novel kind of hydrophilic polymeric monolithic material was facilely prepared via epoxy-amine ring-opening reaction.The process for preparing the hydrophilic monolithic material by this method is very simple.Only a single heating reaction is required,which eliminates the complex preparation process of traditional hydrophilic materials and the need for multi-step modification.The prepared monolithic materials could be used not only as a capillary monolithic column for cLC,but also to enrich glycopeptides in the hydrophilic interaction chromatography(HILIC).Physical Characterization and chromatographic analysis of the monolithic column show that it has good stability and permeability.Moreover,5 alkylbenzenes were separated under the mobile phase of ACN/H2O(35/65,v/v).When the linear velocity was 0.45 mm s-1,the column efficiency reached a maximum of 76,640 N m-1.At the same time,the baseline-separations of both phenolic and aniline mixtures were achieved under the mobile phase of ACN/H2O(60/40,v/v).It should be pointed that the prepared monolithic column was further used to separate mixtures of toluene,dimethyl formamide,acrylamide and thiourea in HILIC at the mobile phase of ACN/H2O(95/5,v/v).Furthermore the prepared monolithic material was used to enrich glycopeptides from the tryptic digest of human immunoglobulin G(IgG).Compared with the MALDI-TOF mass spectra of before and after enrichment,the signal of glycosylated could be clearly seen after enrichment,while the interference of non-glycosin was almost completely eliminated.