Monolithic silica xerogel capillary column for separations in capillary LC and pressurized CEC.

Monolithic capillary columns were prepared by the reaction of a mixture of potassium silicate solution and formamide. The surface of the monolith was coated with a thin film formed by a sol-gel method to increase the surface area of the monolith and simultaneously covered with C8 as stationary phase for reversed-phase separation. The morphology of the monolithic column was investigated by SEM. Monolithic columns prepared in this manner showed high permeability and can be operated in capillary LC (CLC) mode at a pressure of 20 psi. PAHs were used to evaluate the separation performance of the stationary phase using CLC and pressurized CEC (pCEC). Efficiencies of 20 000 and 28 000 plates per meter for naphthalene were obtained in CLC and pCEC modes, respectively. Improvement in column efficiency and reduction in analysis time over CLC and improvement in operation facility and separation selectivity over CLC were found using pCEC mode.