Strategy to control the amount of titania dispersed on SBA-15 surface preserving its porosity, aiming to develop a sensor for electrochemical evaluation of antibiotics

In the present work, an experimental procedure was developed in order to obtain different amounts of titanium oxide highly dispersed on the surface of mesoporous ordered silica material, SBA-15 type. The procedure is based on successive grafting reactions using small quantities of titanium alkoxide precursor that allow obtaining high amounts of highly dispersed titanium oxide, even after calcination at 500 °C, and at the same time, preserves the mesopore structure of the silica. The proposed procedure avoids the aggregation of titanium oxide that forms crystallites, which can be detected by XRD, and consequently closes the mesopores. This behavior produces the artifact known as Tensile Strength Effect (TSE) which is detected by textural analysis. Mesoporous silica containing highly dispersed titanium oxide was applied as modifier MWCNT paste electrode for evaluation of sulfamethoxazole (SMZ) and trimethoprim (TMP). The electrode presents excellent response for simultaneous determination of both antibiotics in a wide linear concentration range. It presents high sensitivity, 10.5 and 25.1 nA μmol−1·L and low detection limit 60 and 70 nmol L−1, for SMZ and TMP respectively.