Preparation And Chromatographic Performance Evaluation Of Amine Polymer Hydrophilic Interaction Chromatography Stationary Phases

At present,most of Hydrophilic Interaction Chromatography(HILIC)stationary phases are formed by bonding or coating different types of polar organic or inorganic substances on the surface of a carrier such as silica gel,in order to enhance the hydrophilicity or stability of the HILIC stationary phase with good selectivity and separation performance.Since the introduction of the HILIC concept,various types of amino-based HILIC stationary phases have been developed.The introduction of the polar groups,such as primary amino groups,secondary amino groups,tertiary amino groups,and quaternary ammonium salts,could enrich the type of HILIC stationary phase and obtain more stable phases.These compounds have become the excellent raw materials for the preparation of high-performance HILIC stationary phases.Based on the above research background,three different types of amine type HILIC stationary phases were prepared,and various characterizations and chromatographic separation properties were evaluated,separatively.The main work of this paper is as follows:(1)A novel HILIC stationary phase was prepared by grafting methacryloyloxyethyltrimethylammonium chloride(MOTAC)monomer onto the surface of propyl silica by atom transfer radical polymerization(ATRP).Characterization by infrared spectroscopy,elemental analysis or nuclear magnetic resonance of each intermediate product showed that MOTAC was successfully immobilized on the surface of the carrier.Twenty polar compounds,such as nucleosides,bases,sugars,and organic acids,were used as analytes,and the prepared stationary phase was evaluated for chromatographic separation performance in HILIC mode.As a result,it was found that the prepared stationary phase exhibited good separation performance for the above analytes,and the effects of different chromatographic conditions(mobile phase composition,mobile phase type,buffer salt and pH,column temperature)on analyte retentions were consistent with the typical HILIC retention features.(2)A polyethyleneimine containing the trimethoxysilane groups was bonded onto a silica gel surface by a coupling method to obtain a novel ammonium-based HILIC stationary phase.Using infrared spectroscopy,elemental analysis,etc.,it was characterized that the preparation of the stationary phase was successful.Six kinds of nucleosides,four bases,and five kinds of vitamins were used as analytes.The separation performance of the prepared stationary phase was evaluated in HILIC mode,and the influence of factors,such as the organic matter content,the mobile phase type,the buffer salt concentration in the mobile phase,and the column temperature,were investigated,respectively.These results show that the stationary phase could effectively identify and separate the nucleoside and nucleobase compounds,but the separation effect on vitamin compounds was not good.In general,this stationary phase conforms to the typical hydrophilic mode of HILIC.(3)The methyl acrylate(MA)was bonded onto the surface of aminopropyl silica gel by Michael addition reaction.The obtained derivative gel was reacted with ethylenediamine(EDA),diethanolamine(DEA),ethanolamine(EA),diethylenetriamine(DETA),and triethylenetetramine(TETA),respectively.Then,five different types of amino or hydroxyl terminated HILIC stationary phase were obtained,and the above five stationary phases were characterized by infrared spectroscopy and elemental analysis,respectively.At the same time,ten nucleoside and base samples were separated and evaluated in the HILIC model.The results show that the above five kinds of stationary phases could separate the above analytes to different extents,and the chromatographic performances of the amino-terminated stationary phase were better than those of the hydroxyl-terminated stationary phase,indicating that the amino group is greatly contributed to the HILIC separation.