Study Of Polyethyleneimine Embedded Mixed-mode Liquid Chromatographic Stationary Phase

Objective:(1)A polyethyleneimine embedded alkyl mixed mode chromatographic stationary phase(Sil-PEI-STA)was prepared.Hydrophobic,hydrophilic and ionic compounds could be separated on the stationary phase.In addition,separation mechanism under different modes was researched on the stationary phase.(2)A polyethyleneimine embedded L-phenylalanine mixed-mode chromatographic stationary phase(Sil-PEI-APH)was prepared,then the separation of hydrophobic,hydrophilic and ionic compounds on the stationary phase was realized under different separation modes,the stationary phase can be further used for the separation of enantiomer.Methods: Firstly,a polyethyleneimine embedded alkyl mixed-mode stationary phase was synthesized by epoxide ring-opening reaction.Secondly,polyethyleneimine and acetylated-L-phenylalanine were covalently grafted on the surface of silica for the synthesis of a novel reversed phase,hydrophilic and ion-exchange mixed mode stationary phase.The two synthetic stationary phase materials were characterized by elemental analysis,infrared spectroscopy,thermogravimetric analysis and scanning electron microscopy.High pressure homogenate method was used for packing the mixed-mode stationary phase materials for chromatography column.These chromatographic columns with different separation modes were used for the separation of hydrophobic,hydrophilic and ionic compounds.The retention mechanism of the two stationary phases was studied by the influence of mobile phase composition and the change of pH on the retention of the compounds.Results: Based on the results of elemental analysis,infrared spectroscopy,thermogravimetric analysis and scanning electron microscopy,it was proved that stationary phases of Sil-PEI-STA and Sil-PEI-APH were successfully synthesized.Based on the stationary phase of Sil-PEI-STA,five kinds of alkyl benzenes,four kinds of position isomers,five kinds of polycyclic aromatic hydrocarbons,five kinds of nucleosides,three kinds of benzoic acids,three kinds of phenols,five kinds of flavonoids and six kinds of anilines were obtained baseline separation.Then five kinds of alkyl benzenes,three kinds of position isomers,five kinds of polycyclic aromatic hydrocarbons,five kinds of nucleoside,four kinds of benzoic acids,three kinds of phenols,four kinds of flavonoids and five kinds of anilines were obtained baseline separation on the Sil-PEI-APH stationary phase.Through the influence of different proportions of acetonitrile content of mobile phase on the retention of compounds,which showed that alkyl benzenes,position isomers and polycyclic aromatic hydrocarbons were separated under reversed mode,and the separation of nucleosides was realized under hydrophilic interaction mode.By studying the effect of different pH on retention of compounds,it was proved that benzoic acids and phenols were separated mainly by ion exchange mode.There were various kinds of retention mechanisms on these stationary phases for the separation of flavonoids and anilines.Conclusion:(1)Polyethyleneimine is an excellent functional monomer and intermediate,which can be used for the preparation of various types of mixed-mode stationary phases.(2)Two hydrophobic/hydrophilic/ion-exchange mixed mode stationary phases prepared in the research have good selectivity and can achieve effectively separation of different types of compounds.(3)Based on the excellent selectivity of these mixed-mode stationary phases,which have the potential for the separation of complex samples in practical systems.(4)The Sil-PEI-APH chromatographic column has the capability of both mixed-mode separation and chiral resolution ability,and the development of these mixed-mode chiral columns will become a hot topic in drug analysis.