Preparation of new hydrophilic monolithic columns and their applications in capillary liquid chromatography and pressurized capillary electrochromatography

Abstract

New hydrophilic monolithic columns were prepared with {[3-(methacryloylamino) propyl] dimethyl(3-sulfopropyl)ammonium hydroxide inner salt (SPP)} as monomer, pentaerythritol triacrylate (PETA) as crosslinking agent, azobisisobutyronitrile (AIBN) as initiator with two different porogens consisting of ethanol/ethylene glycol and methanol/1 ,4-butanediol, separately. In order to obtain monolithic columns with satisfactory efficiency, electroosmotic flow (EOF) velocity and permeability, the contents of the polymerization mixture were investigated and optimized. The performances of the two columns were compared in the permeability and separation performance. It was found that the monolithic column prepared with ethanol/ ethylene glycol had a better column efficiency and selectivity than that with methanol/1,4-butanediol, but was inferior to the latter in permeability. The effect of salt concentration (from 10 to 70 mmol/L ammonium formate) on the retention of nucleosides was investigated. It was observed that the retention factors of these nucleosides increased at first and then decreased. The columns were used in capillary liquid chromatography (cLC) and pressurized capillary electrochromatography (pCEC) for the separation of a test mixture of amines, phenols and nucleosides separately, and satisfactory separations for these samples were achieved. The column used in pCEC system showed better separation and higher speed of the mixture consisted of phenols and nucleosides compared to those used in cLC system.