Selected ion flow tube mass spectrometry analyses of laser decomposition products of a range of explosives and ballistic propellants

Abstract

The rationale of this study was to quantitatively characterise differences and similarities in the gaseous and volatile components of the decomposition products of 38 types of commercially produced explosives and propellants. A combination of laser-induced breakdown (LIB) and selected ion flow tube mass spectrometry (SIFT-MS) methods was used. The surface of the bulk samples was irradiated by a sequence of 10 laser pulses, 150 mJ each, in an argon atmosphere to simulate the explosion or combustion on a microscopic laboratory scale. The gas from the reaction zone was analysed in real time by SIFT-MS. The concentrations of the decomposition products (NH₃, HCN, HCHO, NO, NO₂, HONO, HNO₃, C₂H₅OH, CH₃CN, DMNB, C₂H₆CO, C₂H₂ and nitroglycerine) were determined and statistically processed using multivariate principal component analysis (PCA). The results revealed that there are similarities in the quantitative compositions of the decomposition products for similar explosives and similar propellants. PCA visualisation highlights that characteristic combinations of compounds correspond to the decomposition of nitrocellulose and nitrocellulose-based propellants (including trade mark Lovex), and different combinations correspond to various plastic explosives (trade mark Semtex). The conclusion of this work is that the present methodology can be used for safe and non-destructive studies of characteristic explosion products without the need for the initiation of hazardous quantities of explosives in the form of test charges.