Examination of Firearms Review: 2007 to 2010 - Interpol

gaseous state), we see now a diversification into other, ultra-modern, techniques
such as LASER Spectroscopy and DESI probes.
3.3.1 Screening of gun propellant powder components
NIST (146) has produced a Standard Reference Material with known
concentrations of nitroglycerin, (N-nitroso)diphenylamine and ethylcentralite. This
material can be used to validate analysis methods in an accreditation effort of
forensic laboratories, or as a proficiency standard. NIST is currently developing
two more standards aimed at the determination of trace amounts of high
explosives. One is developed for calibration of detection equipment as used in
airport security, and the other for measurements associated with remediation of
contaminated soil.
Haag et al. (147) have investigated the new Blackhorn 209 propellant, a novel
formulation that is a substitute for black powder in muzzle-loading firearms. It
provides bullet speeds slightly higher than the equivalent modern black powder
formulations, but leaves mildly corrosive residues in the bore of the firearm and in
the cartridge cases. This new powder is unlikely to turn up in many cases due to
high cost and narrow application, but may turn up in cases involving gun bursts
and pipe bombs
3.3.2 Instrumental methods
A number of techniques have been used to detect organic residues in different
applications and varying substrates. Among them, Solid Phase Micro-Extraction
(SPME) is used in combination with GC or Ion Mobility Spectrometry (IMS).
Weyermann et al. (148) used GC-MS analysis after SPME sampling of fired 9
mm cartridge cases. They were able to identify thirty two organic volatile
compounds, some of which could be traced until up to 32 hours after the shot.
The problem is that, as work in this area is very original, the exact origin of most
of these compounds is still unknown. The study shows further that the largest
problem involved with the use of SPME is the reproducibility of the
measurements of nanogram-range quantities of material. Joshi et al. (149), on
the other hand, successfully used SPME and Ion Mobility Spectrometry for the
detection of odour signatures of smokeless powders. Besides being an
instrumental alternative to canines for the detection of compounds used in homemade
explosive devices, their method detects also components for which the
dogs are not useful. For instance, 2-ethyl hexanol and 2,4-DNT were detected by
canines, while diphenyl amine (DPA) and ethylcentralite (EC) were not of interest
to them. As IMS instruments are readily available, e.g.. in airports, where they
are used for detection of illicit substances, these results therefore complement
the canine detection by instrumental techniques.
All these techniques have in common that the analytes are being sampled and
concentrated on a carrier substrate prior to analysis. On the other hand,
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