Preparation of fritless packed silica columns for capillary electrochromatography

Fritless packed silica gel columns were prepared using sol-gel technology. A part of a 75 mu m i.d. fused silica capillary was filled with a mixture o f tetramethoxysilane and poly(ethylene glycol). After gelling at 40 degrees C and heating at 300 degrees C, the resultant silica gel was derivatized w ith dimethyloctadecylchlorosilane. A scanning electron micrograph of a cros s-section of the capillary column showed that the gel took the form of a sp herical particle aggregate and adhered to the column inner wall. The column performance was evaluated for electrochromatography using acetonitrile-50 mM HEPES buffer (pH 6.6) (60/40 or 40/60, v/v) as the mobile phase. An elec troosmotic flow of 1.0 mm/s was generated with (60/40, v/v) acetonitrile/HE PES buffer at a field strength of 546 V/cm. Using a sol-gel-derived packed column at an electroosmotic flow of 0.5 mm/s, efficiencies of up to 1.1 x 1 0(5) plates/m were obtained for retained solutes.