Preparation Of Polymer Modified Silica Based Stationary Phases And Applications In Hydrophilic And Mixed Mode Liquid Chromatography

High performance liquid chromatography is the most commonly used technique for separating and purifying a variety of compounds,which has found extensive use in a number of disciplines including biomedicine,food safety,and environmental testing.In recent years,hydrophilic interaction liquid chromatography and mixed mode liquid chromatography have been demonstrated considerable application potentially due to the rising demands for the separation of polar and complicated samples in many fields.The focus of chromatography research has shifted to the creation of novel hydrophilic stationary phases and mixed mode stationary phases.In this work,two silica based stationary phases that were employed in hydrophilic and mixed mode liquid chromatography respectively were designed and manufactured.In addition,the chromatographic retention behaviors and separation performance of two stationary phases were also examined.By using the vinyl groups on silica surface as the surface-initiated group,and acrylamide monomer as the function repeating unit for polymerization,a polyacrylamide modified hydrophilic stationary phase was prepared successfully.The stationary phases exhibited great hydrophilic separation performance and typical hydrophilic retention characteristics.It was discovered by investigating the growth kinetics of polyacrylamide that the amounts of both vinyl and acrylamide monomers could control the polymer chain structure on stationary phases.In terms of separation performance,stationary phases with higher polyacrylamide bonding amounts exhibited stronger retention and higher hydrophilic selectivity,while the stationary phases with higher vinyl contents owned better separation efficiency,with the highest theoretical plate number reached 119966/m for orotic acid.The adjustable structure and separation performance of the stationary phases offers a variety of analytical and preparation applications.A poly(styrene-acrylic acid)copolymer modified stationary phase for mix mode liquid chromatography was prepared via one-pot free radical polymerization,in which styrene and acrylic acid were used as the functional repeating units for polymerization.In the performance evaluation of the stationary phase,the retention results of hydrophobic and hydrophilic analytes revealed that the stationary phase had a typical reversed-phase/hydrophilic retention behavior,and the separation performance of alkyl benzenes,polycyclic aromatic hydrocarbons and nucleoside bases on the stationary phase was better than C18 and amide stationary phases.In addition,the stationary phase effectively identified and separated basic compounds due to the presence of carboxylic acid groups.The experimental results showed the stationary phase had a hydrophobic/hydrophilic/cation exchange mixed retention mechanism and great reproducibility in the separation of mixed samples.Furthermore,it was found that the method had good batch stability in this work,which provided a new approach for the development of other novel polymer modified silica stationary phases.