Development and characterization of hydrophobic organic monolithic columns for use in capillary electrochromatography

Abstract Monolithic poly(octadecyl methacrylate- co -ethylene dimethacrylate) capillary columns for use in capillary electrochromatography (CEC) were developed and characterized by porosimetric measurements and scanning electron microscopy (SEM). The stationary phases were prepared using 2-acryloylamido-2-methylpropanesulfonic acid (AMPS) as the ionizable monomer and 2,2′-azobisisobutyronitrile (AIBN) as the initiator of thermal polymerization, which occurred at 60 °C. The porogenic solvents used in this work were amyl alcohol and 1,4-butanediol, in the proportion 65:35 (v/v). The ratio between monomers and porogenic solvents was varied in a range of 60 to 80% (v/v) of porogenic agents. The porosimetry showed that the increase in content of porogenic solvents caused an increase in pore surface area, but a relationship with the separation efficiencies was not observed. SEM agreed with the conclusions made through porosimetry, where decreases in globule size could be noted with increases in porogenic solvents.