Open Tubular Monolith Formation and C18 Ligand Immobilization in Silica Capillary by Microwave Heating for Capillary Electrochromatography

A thin and compact silica monolith was formed on the inner surface of silica capillary by microwave heating. Monolith formation by microwave heating was fast and effective, and its C18 modified CEC open tubular column showed very good separation efficiency. Analysis time of the open tubular monolithic capillary column made by microwave heating was much shorter than that of the monolithic column made by thermal heating while the separation efficiency was better. C18 modification by thermal heating, however, rather than by microwave heating, showed better results. Monolith formation by microwave heating coupled with C18 modification by thermal heating is recommended to make a good open tubular CEC column that enables rapid and efficient separation. The methods of C18 modification to silica gel are well described in the literature. Three C18 modification methods are known by which three different types of C18 stationary phases are obtained, respectively-- a brush form, an oligomeric form, and a bulk form