Preparation and application of an emodin-bonded silica gel chromatographic column for high performance liquid chromatography

An emodin-bonded silica gel stationary phase( ESP) for high performance liquid chromatography has been synthesized by the intermediate method. The preparation process was as follow s: γ-glycidoxypropyltrimethoxy silane( KH-560) firstly reacted with emodin ligand;then the intermediate was chemically immobilized to the surface of silica gel. Characterization of ESP was carried out with Fourier transform infrared spectroscopy( FTIR),elemental analysis and thermogravimetric analysis. Naphthalene was used as a probe to determine the column efficiency with methanol-water( 60∶ 40,v/v) as binary mobile phase at a flow rate of0. 8 mL/min. In order to elucidate the related separation mechanism,ESP was used to separate a series of neutral,basic and acidic aromatic compounds,as well as a sample of w ind medicated oil. The conventional C18column and phenyl column were also tested under the same chromatographic conditions for comparison. The results show ed that the emodin ligand was successfully bonded to the surface of spherical silica gel with a 0. 23 mmol/g of bonded amount,and the theoretical plate number of ESP column was about 19 874 N/m. The coupling reagent chains and anthraquinone rings in ESP offered a structural basis for hydrophobic interaction.Meanw hile,the emodin ligands provided π-π or p-π,charge transfer,hydrogen bonding,dipole-dipole action sites for different analytes. The synergistic reaction of various action sites endow ed ESP column special and excellent chromatographic separation selectivity. And a baseline separation of polar compounds such as amines and phenols on ESP was easily achieved byusing common and cheap methanol-water mobile phases without buffer salts. The experimental conditions were simple and convenient.