Cathodic stripping voltammetric assay of HMX explosive on a carbon nanotube/Ag nanocomposite modified electrode

HMX, also called known as cyclotetramethylene-tetranitramine, is a powerful and relatively insensitive nitroamine high explosive. This nitroaromatic explosive, widely used in military and civil applications, can enter the environment through water and soil. Degradation of explosives in the environment is generally slow and initial biotransformation products are often carcinogenic [1]. At present, reverse-phase HPLC have been developed to accurately quantify the concentration of HMX in a variety of matrices in environmental assessments [2]. Also, a range of materials and techniques have found application for cathodic measurements of nitroaromatic and nitramine explosive compounds [1,3], however, limited studies concern the application of voltmmetric methods for the detection and determination of HMX, and in practical, the detection of this explosive on the conventional electrodes, in the aqueous and organic conditions is hard .In this research, various electrochemical methods was used to study and determine HMX, on a multi-walled carbon nanotubes-Ag nanoparticles (MWCNTs/Ag) modified glassy carbon electrode (GCE). Various kinetic parameters such as transfer electron number, transfer proton number and heterogeneous rate constant and diffusion coefficient constant of HMX were calculated, and various experimental parameters were also optimized. The results demonstrated that the electrochemical response of HMX by adsorption stripping voltammetry on MWCNTs/Ag film can remarkably be enhanced compared to bare carbon nanotubes electrode. Cyclic voltmmatric studies of high concentration of HMX on the GCE doesn’t show any reductive signal, but on the MWCNTs modified electrode display a relatively sharp cathodic peak, and by MWCNTs/Ag modified electrode, the reduction potential changes and facilities from -0.7 V (vs. SCE) to -0.3 V, due to specific electrocatalytic properties of the this nanocomposite electrode. Chronoamperometry studies show, a diffusion controlled process with diffusion coefficient of 2.01×10−4 cm2 s−1, and the number of electrons transferred for electrochemical reduction of HMX are near to 1.72. Under optimized conditions, the reduction peak have a linear dynamic ranges of 10.0-100.0 M with the practical detection limit of 7.0 M and a precision of 1.0% (RSD for 5 analysis). This modified electrode was properly used for determination of HMX in soil and ground water samples with satisfactory results.