Preparation of on-column frits in packed fused silica capillaries by sol-gel technology

Existing methods for preparing frits in packed fused silica capillaries as used for electrochromatography and micro HPLC are not applicable to all sil ica based packing materials and involve a high thermal stress for both the stationary phase and the fused silica tubing including the polyimide coatin g. A new procedure for the production of such on-column frits under mild co nditions by a sol-gel type reaction of polydimethoxysiloxane (PDMOS) is des cribed in this paper. Reaction conditions were established for optimum mech anical stability and high permeability of the frits, Frits produced in this manner showed no noticeable effect on the overall efficiency.