Forensic Analysis Of C-4 And Commercial Blasting Agents For Possible Discrimination

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Steele, Katie
Forensic; C-4; RDX; Process Oils
thesis / dissertation description
The criminal use of explosives has increased in recent years. Political instability and the wide spread access to the internet, filled with "homemade recipes," are two conjectures for the increase. C-4 is a plastic bonded explosive (PBX) comprised of 91% of the high explosive RDX, 1.6% processing oils, 5.3% plasticizer, and 2.1% polyisobutylene (PIB). C-4 is most commonly used for military purposes, but also has found use in commercial industry as well. Current methods for the forensic analysis of C-4 are limited to identification of the explosive; however, recent publications have suggested the plausibility of discrimination between C-4 samples based upon the processing oils and stable isotope ratios. This research focuses on the discrimination of C-4 samples based on ratios of RDX to HMX, a common impurity resulting from RDX synthesis. The relative amounts of HMX are a function of the RDX synthetic route and conditions. RDX was extracted from different C-4 samples and was analyzed by ESI-MS-SIM as the chloride adduct, EI-GC-MS-SIM, and NICI-GC-MS. Ratios (RDX/HMX) were calculated for each method. An analysis of variance (ANOVA) followed by a Tukey HSD allowed for an overall discriminating power to be assessed for each analytical method. The C-4 processing oils were also extracted, and analyzed by direct exposure probe mass spectrometry (DEP-MS) with electron ionization, a technique that requires less than two minutes for analysis. The overall discriminating power of the processing oils was calculated by conducting a series of t tests. Lastly, a set of heterogeneous commercial blasting agents were analyzed by laser induced breakdown spectroscopy (LIBS). The data was analyzed by principal components analysis (PCA), and the possibility of creating a searchable library was explored.