Palladium-doped mesoporous silica SBA-15 modified in carbon-paste electrode as a sensitive voltammetric sensor for detection of oxalic acid

We developed simple and effective method for the synthesis of Pd-doped mesoporous silica SBA-15 (Pd/SBA-15). Techniques of X-ray diffraction, scanning electron microscope, energy dispersive X-ray and nitrogen sorption isotherms techniques were used to characterize the structure and properties of the Pd/SBA-15. Due to the large surface area and high catalytic behavior of Pd/SBA-15, carbon paste electrode modified with Pd/SBA-15 (Pd/SBA-15/CPE) was prepared. The sensor responded linearly to oxalic acid (OA) in the concentration of 10-140 μM with a detection limit of 0.4 μM at 3σ using linear sweep voltammetry. Also, Pd/SBA-15/CPE was used for OA detection in real samples. The proposed method showed a good result, indicating that the present modified electrode could be applied to determine OA in food samples. The accuracy of the method was evaluated as excellent comparing the detection results with that obtained using conventional KMnO4 titration method. Possible interferences such as glycine, alanine, ascorbic acid, dopamine, uric acid, l-cysteine, glutathione, d-penicillamine, cystamine, N-acetyl-l-cysteine and lysine for the detection of OA at the Pd/SBA-15/CPE were investigated. The results showed that these mentioned compounds did not show interference.