An initial evaluation of stable isotopic characterisation of post-blast plastic debris from improvised explosive devices

Abstract 

A number of two-way radios, similar to those which have been employed to initiate Improvised Explosive Devices (IEDs), were acquired from a commercial supplier and grouped into four pairs. Samples of plastic material were collected from five distinct regions of each radio and analysed by Infrared and Raman spectroscopy to identify the nature of the material. One radio of each pair was then subjected to detonation with a commercially available plastic explosive. The combination of radio and explosive was considered to be representative of the components of an IED. Following detonation, fragments were recovered and, where possible, identified as specific sampling points of the radio.

A combination of δ²H and δ¹³C stable isotopic analysis of material from each of the five sampling points was found to provide a pattern which was characteristic of a given radio and provided a means to associate pairs of radios. When few fragments were recovered, no positive association could be made between the fragments and the paired, undamaged radio. This was attributed, in part, to manufacturing variation in the radios. However, when three or more post-blast fragments were recovered it was possible to associate these with the paired, undamaged radio with a high degree of certainty.

Keywords: Isotope ratio, Isotope ratio mass spectrometry (IRMS), Improvised explosive device (IED), Post-blast debris