Stationary-phase immobilization, chemical bonding approach

At present it seems that immobilization of silica-based particles within a packed capillary by hydrothermal treatment or sol-gel adhesion represent a simpler approach to the preparation of silica-based monoliths for capillary electrochromatography [302,332-334]. Particle fixation is achieved through adhesion by silica precipitated in the interparticle space released from the particles by hydrothermal treatment, or formed by hydrolysis and polycondensation of a solution of alkoxysilanes (sol-gel process). Since only relatively low temperatures are used in both processes, chemically bonded phases can be immobilized as easily as silica. The selectivity and separation efficiency of immobilized particle beds is generally similar to that of slurry packed columns prepared from the same stationary phases. 

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