TiO2 and cobalt double transition metal nano cluster doped LTA zeolite as a nonenzymatic electrochemical sensor toward glutamic acid ultra-trace determination

Rapid and accurate detection of glutamic acid has always been our focus. Herein, we propose a non-enzymatic electrochemical sensor based on low-cost double transition metal oxides to detect glutamic acid efficiently. In this study, LTA nano-zeolite cages are synthesized by hydrothermal method. To further improve the conductivity, TiO 2 and Co metal nanoparticles are combined with nano-zeolite cages with multiple electrocatalytic sites to form TiO 2 -Co/LTA NPs. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and high-resolution projection electron microscopy (TEM) were used to characterize the materials before and after adsorption and oxidation of glutamic acid. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were used to test the oxidation and adsorption properties of the modified sensor after adding glutamic acid. Under the optimal pH condition, the sensor detection range is 3.0 × 10 −12 –3.0 × 10 −8  M and the detection limit (LOD) can reach 1.0 × 10 −12  M. In addition, the sensor has good selectivity for glutamic acid, even in the presence of multiple other amino acids. The practical application shows that the sensor can be used to detect glutamic acid in milk, seawater and serum samples with a recovery rate of 90.0 % to 110.0 % and RSD <4 %. We anticipate that this work will provide new ideas for the development of third-generation non-enzymatic sensors for glutamic acid monitoring.