Open tubular liquid chromatography using a sol-gel derived stationary phase

An organically modified silica glass material containing octyl groups (C₈) was fabricated by the sol-gel process and coated onto the inner walls of fused silica capillaries. The coating was used as the stationary phase for reversed-phase open tubular liquid chromatography (OTLC). The sol-gel process facilitated the fabrication of a porous silica glass layer with the stationary phase in one single step. The high surface area of the coating, characteristic of materials fabricated by the sol-gel process, resulted in capillary columns with a stronger retention than those prepared by a conventional procedure. The molar ratio of the precursors was used as a tunable parameter to adjust the retention and selectivity of the stationary phase. The column performance was evaluated using anthracene derivatives as model analytes which were monitored by laser-induced fluorescence (LIF) detection. Separation efficiencies of 200,000 theoretical plates/meter were typical for the model compounds. Solute selectivity of the sol-gel derived stationary phase was found to be similar to the selectivity of HPLC monomeric-type phases.