Reversed-phase electrochromatography with a monolithic microcolumn prepared in a 2.2-mm-inner diameter fused-silica tube.

Capillary electrochromatography possesses advantages of high separation efficiency and velocity, but it also has its disadvantages due to its small inner diameter, such as poor detection sensitivity, low sample capacity, and some trouble in its column preparation. To overcome these shortcomings, a monolithic microcolumn with a surface area larger than 200 m2/g was prepared by sol-gel polycondensation of tetraethoxysilane-hydrochloric acid-poly(ethylene glycol) and filling with fine quartz sand in a 2.2-mm-i.d. fused-silica tube. The prepared microcolumn was used in the separation of aromatic compounds by reversed-phase electrochromatography. Some factors that affected electroosmotic flow were explored, such as electric field strength, buffer concentration, and buffer pH. Acetonitrile concentration in the mobile phase was investigated for phenol, benzene, and naphthalene separation. The separation results were satisfying with the electrochromatographic microcolumns. The detection limits of phenol, benzene, and naphthalene were 0.07, 0.26, and 0.04 mg/L, respectively.