Retention properties of mesoporous silica-based materials

The partition and retention properties have been studied of mesoporous sili cas prepared using a surfactant-based supramolecular templating approach to wards environmental pollutants (trichloroacetic acid and haloderivatives su ch as chloroform, 1,1,1 -trichloroethane, trichloroethylene and tetrachloro ethylene). Gas-chromatography and suppressed anion-exchange chromatography have been used to evaluate the amount of retained analytes. The effect of t he composition (presence and absence of the surfactant templating agent and of aluminum) and the influence of synthesis procedure of mesoporous silica tes on the sorption performances have been considered. Calcined materials d o not show affinity for ionic analytes. The same materials show good affini ty for non-ionic analytes: different retention properties towards the teste d molecules are observed, interpreted in terms of van der Waals and hydroge n bonding interactions between silica surface and analytes. As-prepared mat erials show excellent retention performances towards TCA, which depend on t he conditions used for the synthesis. All this provides the basis for potential applications of these materials a s preconcentrators and sorptive chromatographic substrates for selective se paration and/or enrichment (removal) of specific classes of analytes. (C) 2 000 Elsevier Science B.V. All rights reserved.