Electrochemical synthesis of (poly)dimethoxyaniline on glassy carbon electrodes and their applications in the detection of l- and D-Glutamic acids

2,5-dimethoxyaniline was electrochemically polymerized on glassy carbon electrodes, resulting in significant enhancement on the oxidation of glutamic acids. Differential pulse voltammetry of the thus-modified glassy carbon electrodes in a 0.1 mM of D- and L-glutamic acid solution generated two isolated peaks that were separated by more than 400 mV, indicating the feasibility of using this low cost and readily-to-fabricate platform for differentiating glutamic acid chiral molecules. Scanning electron microscopy measurements show that the in-situ synthesized 2,5-dimethoxyaniline polymer has a chain structure consisting of many nanometer size particles. Cyclic voltammetry experiments suggest that the oxidations of D- and L-glutamic acids are both charge-transfer controlled processes. Using cyclic voltammetry method, the anodic peak currents were found to have a linear relationship with the concentration of glutamic acids within the range between 0.5 and 15.0 mM, with a detection limit of 0.11 mM for L-glutamic acid and 0.26 mM for D-glutamic acid. The device-to-device reproducibility is great, confirming the robustness of this modification method.