Chromatographic characterisation of a novel type of monolithic methylsilsesquioxane-based HPLC column

A novel monolithic methylsilsesquioxane-based material with hierarchical pore structure was prepared and tested for its applicability as stationary phase for RP-HPLC. The monolithic material is produced using sol-gel chemistry according to a proprietary protocol developed in our working group. A procedure for the production of HPLC columns from the self-contained monolithic material is described. The chromatographic performance and the reproducibility of the column production was tested using the procedures of the widely accepted Tanaka test and suitable parts of the Engelhardt test which were applied to a set of four monolithic columns produced under identical conditions. The test proved the excellent hydrophobic selectivity and silanophilic behaviour of the new stationary phase material. According to the tests on steric and shape selectivity, there are strong indications that this type of material also acts as restricted access material. This assumption is further supported by the presence of a high fraction of micropores as was evidenced by physical characterisation of the material. The novel stationary phase material showed great potential for the separation of small apolar substances and was found to be particularly useful in the separation of basic compounds due its excellent silanophilic interaction.