Optimization of Headspace Solid‐Phase Microextraction Technique for Extraction of Volatile Smokeless Powder Compounds in Forensic Applications

Abstract

Smokeless powders are low explosives and are potentially found in cases involving firearms and improvised explosive devices. Apart from inorganic compound analysis, forensic determination of organic components of these materials appears as a promising alternative, especially the chromatographic techniques. This work describes the optimization of a solid-phase microextraction technique using an 85 μm polyacrylate fiber followed by gas chromatography-flame ionization detection for smokeless powder. A multivariate experimental design was performed to optimize extraction-influencing parameters. A 2(4) factorial first-order design revealed that sample temperature and extraction time were the major influencing parameters. Doehlert matrix design has subsequently selected 66°C and 21 min as the compromised conditions for the two predetermined parameters. This extraction technique has successfully detected the headspace compounds of smokeless powders from different ammunition types and allowed for their differentiation. The novel technique allows more rapid sample preparation for chromatographic detection of smokeless powders.

Study of the Behaviors of Gunshot Residues from Spent Cartridges by Headspace Solid‐Phase Microextraction–Gas Chromatographic Techniques

“…Among the eight tested standards, the headspace composition of GSR from spent cartridges of SME 9‐mm ammunition fired from a semi‐automatic pistol contained five compounds, namely naphthalene, 2,6‐DNT, 2,4‐DNT, DPA, and DBP. Both EC and MC were undetectable in this experiment, which was also observed in SME 9‐mm smokeless powder composition in our previous work . Similar chromatograms were produced from fresh powders and residue of these powders fired from the same ammunition type .…”

“…A manual SPME holder and SPME fibers coated with 85‐μm polyacrylate (Supelco) were used in the experiment. Optimized SPME protocol was as follows: incubation time, 2 min; extraction time, 21 min; and sample temperature, 66°C . Spent cartridge in the vial was placed horizontally with screw cap closed tightly in an oven.…”

Organic compositional analysis of propellant powders using monolithic material sorption extraction (MSSE)-a feasibility study

“…AKII is a stabiliser that may be used as an additive in propellant powder and is thus also associated with OGSR materials [21][22][23][24][25]. DPF has only been mentioned in conjunction with OGSR in the literature on a few occasions, but its function in propellant powder was not reported [26,27]. Figure 4 shows the results of the extraction of Hodgdon HP-38 and Magtech .223 propellants.…”

Recent trends in organic gunshot residue analysis

“…Fibres may be coated with a single polymeric substance such as polydimethylsiloxane (PDMS) or polyacrylate (PA), or with a combination of polymers such as PDMS/divinylbenzene (PDMS/DVB), carboxen/PDMS (CAR/PDMS) or DVB/CAR/PDMS [8,9,13,16,47,50,51]. The PDMS only fibres are non-polar, the PA fibres are polar and the combined coatings are bipolar [8].…”