Preparation And Evaluation Of Two Monolithic Columns Initiated By Redox Systems

Monolithic columns are widely used in fields of life science,pharmaceutical science,environmental science and other fields,because of their advantages such as simple preparation method,good permeability,fast mass transfer,and so on.In this paper,two kinds of polymer monolithic columns are prepared by redox system.The aims are to enhance column efficiency for the separation of small molecules and improve the selectivity of biological macromolecules,respectively.Firstly,the porous monolithic column was prepared in 30 ℃ water bath by using 1,6-hexanediol dimemethacrylate as monomer,ethylene dimethacrylate as crosslinking agent,cyclohexanol and 1,4-butanediol as the porogens,benzoyl peroxide and N,N-dimethylsniline composed of redox system as initiator.The monolithic columns were characterized by scanning electron microscopy,nitrogen adsorption-desorption instrument and mercury intrusion porosimeter,respectively.The results showed that the adopted monolithic column had uniform porous structure with narrow pore size distribution.High performance liquid chromatography experiments showed that the mixture of seven aromatic compounds was successfully separated by using the monolithic column as the stationary phase with the highest column efficiency of 21,000 plates m-1.Furthermore,the homemade monolith was successfully used to separate and quantitatively analyze five active components in traditional Chinese herb Rheum palmatum L.The recovery of this method was in the range of 98.48% to 101.57%.The limit of detection and limit of quantification of five active ingredients were less than 33.7 ng and 90.8 ng,respectively.Secondly,hemin based monolith was prepared via the same initiator at room temperature,using hemin and lauryl methacrylate as co-monomers,ethylene dimethacrylate as crosslinking agent;n-butyl alcohol,ethylene glycol,and N,N-dimethylformamide as porogens.The internal pore structure of the monolithic column was investigated by scanning electron microscopy,nitrogen adsorption-desorption instrument and mercury porosimeter,respectively.The monolithic column was successfully used to separate the mixture of five aromatic compounds with the highest column efficiency as 19,880 plates m-1.Furthermore,the monolithic column exhibited good selectivity and separation ability for complex bio-samples,such as human plasma,chicken egg white,snailase,etc.It was worth mentioning that the column could simultaneously remove three high-abundance proteins in human plasma and separate other proteins,showing that hemin played an important role in improving the selectivity of the monolithic column to protein.The experimental results showed that the present monolithic column prepared by redox initiation system could enhance the column efficiency for separating small molecular compounds.The monolithic column based on hemin greatly improved the selectivity of the polymer monolithic column for the complex biological matrix.