Sensitive electrochemical determination of 3-nitro-1,2,4-triazol-5-one (NTO) by the gold nanoparticles-decorated glassy carbon and smartphone-integrated screen-printed electrodes based on polyethyleneimine linked with crosslinking agent glutaric dialdehyde

Rapid and sensitive voltammetric methods for 3-nitro-1,2,4-triazol-5-one (NTO) determination are scarce in the literature. In the present research, we reported a crosslinked polyelectrolyte-based modified electrode decorated with gold nanoparticles that can be easily formed on the surfaces of both screen-printed electrodes (SPEs) and glassy carbon electrodes (GCEs) for the first time, as well as a voltammetric method for the electrochemical determination of NTO. Cobalt-amine sites formed between PEI and cobalt(II)-acetylacetonate (CoAcAc, an electrocatalyst) are used as a redox mediator. Electrochemical reduction of NTO in the concentration range of 1.3-13 mg L-1 was carried out by both the developed DPV method and a smartphone application. LOD and LOQ values were found to be 0.4 mg L-1 and 1.25 mg L-1 for the developed DPV method and 0.26 mg L-1 and 0.82 mg L-1 for the smartphone implementations, respectively. By taking advantage of the restricted solubility of some other nitro-explosives in water, the solvent medium and the pH of the supporting electrolyte (the pH value at which NTO exists in anionic form, not valid for other explosives) were optimized. In the presence of other nitro explosives, such as trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), 2,4-dinitro toluene (DNT), and 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), the percentage recovery values range from 90.1 to 105.2 % according to the DPV results measured in admixtures with NTO. Surface morphologies of the modified electrode were characterized using scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR), whereas electrochemical studies were performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The detection method proposed was not adversely affected by common soil ions as well as detergents, sugar, sweeteners, caffeine, and paracetamol-based painkillers as camouflage materials for explosives, the negative impacts of which were either nonexistent or eliminable.