Optimisation of recovery protocols for double-base smokeless powder residues analysed by total vaporisation (TV) SPME/GC-MS

Abstract

The investigation of explosive events requires appropriate evidential protocols to recover and preserve residues from the scene. In current protocols however, there is a lack of scientifically rigorous investigation concerning their validity. In this study, a central composite design was used to determine statistically validated optimum recovery parameters for double-base smokeless powder residues on steel, analysed using total vaporisation (TV) SPME/GC-MS. It was found that maximum recovery was obtained using isopropanol-wetted swabs stored under refrigerated conditions for a minimum period, then extracted for 15 minutes into acetone. These parameters were applied to the recovery of post-blast residues deposited on steel witness surfaces following a PVC pipe bomb detonation, resulting in detection of all target components across the majority of samples. Higher overall recoveries were obtained from plates facing the sides of the device, consistent with the point of first failure occurring in the pipe body as observed in previous studies. The methodology employed here may be readily applied to a variety of other explosive compounds, and thus assist in establishing 'best practice' procedures for explosive investigations.

Toward Locard’s Exchange Principle: Recent Developments in Forensic Trace Evidence Analysis

“…APCI-MS was found to be a selective and sensitive approach for the detection of nitrated sugar alcohols. TV-SPME/GC/MS was proposed by Sauzier et al to study the optimum recovery parameters for double-base smokeless powder residues on steel …”

Interpol review of detection and characterization of explosives and explosives residues 2016-2019

“…In a very important study, Sauzier, G., Bors, D., Ash, J., Goodpaster, J., and Lewis, S. attempt “… a central composite design was used to determine statistically validated optimum recovery parameters for double-base smokeless powder residues on steel, analyzed using total vaporisation (TV) SPME/GC-MS.” Importantly, they reported that maximum recovery was by using “… isopropanol-wetted swabs stored under refrigerated conditions, then extracted for 15 min into acetone on the same day as sample collection.” It will be interesting to see if this finding translates to other post blast explosives [ 276 ].…”

Mapping smokeless powder residue on PVC pipe bomb fragments using total vaporization solid phase microextraction

“…Our research group has a long-standing interest in simple IEDs such as pipe bombs. This includes studies of pipe bomb explosions using high speed videography [11,12], chemical analysis of post-blast residues on pipe bomb fragments [13], and quantitation of explosive residues on witness plates placed immediately adjacent to a pipe bomb [14]. The technique that has been used for all of these studies is Total Vaporization Solid Phase Microextraction Gas Chromatography/Mass Spectrometry (TV-the vapor is then sampled using SPME.…”

“…In a similar study, DBSP residues were quantitated on witness plates suspended immediately adjacent to PVC pipe bombs [14]. The concentration of NG was extremely varied, with essentially no NG detected on the witness plate that was facing the fused end of the device.…”