Preparation, characterization and analytical application of a hybrid organic–inorganic silica-based monolith

In the present study, a mercapto groups-incorporated hybrid silica-based monolith, which consists of a continuous porous silica backbone, was successfully synthesized by sol–gel technology. The hybrid silica monolith was characterized by various techniques, such as elemental analysis, scanning electron microscopy, diffused infrared spectroscopy and low temperature nitrogen desorption/adsorption measurements. The results showed that the monolith contains high sulfur content (up to 3.05%) with a hierarchical porous structure (throughpores and mesopores) and large specific surface area (467 m2/g). Due to the favorable chemical reactivity of mercapto pendant moieties, the hybrid monolith can be facilely derivatized to yield various functional groups. In this study, they were oxidized by hydrogen peroxide (30%, w/w) to produce sulfonic acid groups, which exhibited excellent cation-exchange capability. The application of this material is demonstrated by in-tube microextraction of anaesthetics followed by capillary electrophoretic separation. The monolith can be effectively applied to purify and enrich the target analytes in human urine.