Determination of nitroaromatic and nitramine type energetic materials in synthetic and real mixtures by cyclic voltammetry

Nitro-explosives contain reducible aromatic –NO2 groups or cyclic >N–NO2 bonds that may undergo reductive cleavage. This work reports the development of a cyclic voltammetric (CV) assay for nitro-aromatics (trinitrotoluene (TNT), dinitrotoluene (DNT)) and nitramines (1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)) using a glassy carbon electrode. This determination was first used for these energetic materials by resolving current responses of reduction potentials primarily due to one constituent but partly contributed by other constituents. Calibration curves of current intensity versus concentration were linear in the range of 30–120 mg L−1 for RDX with a limit of detection (LOD) of 10.2 mg L−1, 40–120 mg L−1 for HMX (LOD=11.7 mg L−1), 40–120 mg L−1 for TNT (LOD=11.2 mg L−1), and 40–140 mg L−1 for DNT (LOD=10.8 mg L−1). Results showed that the CV method could provide a sensitive approach for the simultaneous determination of RDX and TNT in synthetic and real mixtures. Deconvolution of current contributions of mixtures at peak potentials of constituents was performed by multiple linear regression. The proposed method was successfully applied to the analysis of military explosives comp A5 and octol, and method validation was performed both against HPLC on a comp B (TNT+RDX) sample and against GC–MS on real post-blast residual samples containing both explosives.