Investigations of a sol–gel derived stationary phase for open tubular capillary electrochromatography Original Research Article

Organic–inorganic hybrid glass composites were synthesized using sol–gel processing. These composites were cast onto the inner walls of fused silica capillaries and used as the stationary phase for open tubular capillary electrochromatography (OT-CEC). N-octyl sol–gel processed bonded phases were prepared using a mixture of n-octyltriethoxysilane and tetraethoxysilane (C8-TEOS/TEOS). The synthesis of the sol–gel-processed composite incorporates the stationary phase into the glass formation process. This process consists of hydrolysis and condensation reactions of the C8-TEOS/TEOS mixture. The chemical species present in solution during the sol–gel process, prior to column casting, dictates the characteristics of the final glass composite. Manipulation of the processing parameters allows control of the retentive properties of the sol–gel-derived phase. A correlation between the species present in solution at the time of column casting and chromatographic retention has been established. The column preparation procedure was optimized for the C8-TEOS/TEOS hybrid system. A phase containing octadecyl (C18) groups was also fabricated by sol–gel processing. Using a pressurized coating assembly improved the column-to-column reproducibility. The effect of silanizing the sol–gel-derived material was also studied. Such a silanization, however, did not cause appreciable changes on the performance of the capillary columns.