• Guijt, Rosanne
• Dicinoski, Gw
• Hutchinson, Jp
• Haddad, Paul
• Johns, Ca

Abstract

<p>The analysis of post-blast explosive residues has become an essential tool in counterterrorisminitiatives.</p><p>Explosives based on inorganic salts and peroxides can be constructed using readilyavailable, low cost, and legally purchased components. Examples of their recent use interrorist bombings include: the Unabomber (USA, 1985?1996), the bombing of theWorld Trade Center (USA, 1993), the Murrah Federal Building (USA, 1995), severalterrorist attacks in Indonesia (2002, 2005) and attacks on public transport systems inMadrid (Spain, 2004) and London (UK, 2005).</p><p>Identification of explosives is a topic of considerable interest to forensic scientists andcounter-terrorism authorities. The broad area of explosives analysis can be divided intotwo sub-areas: detection and identification of explosives or their major ingredients priorto detonation (pre-blast screening analysis), or identification of explosives by analysis ofdebris and residues after detonation (post-blast detection analysis). Pre-blast analysis is achallenging problem that requires the ability to rapidly screen for the presence ofinorganic and organic starting materials used to make explosive devices. Such screeningis currently being used at fixed locations, such as airport terminals, in efforts toapprehend potential terrorists. On the other hand, post-blast analyses are required todetermine the type and composition of an explosive after detonation has occurred.Explosive devices have a vast range of chemical compositions, hence a forensic scientistmust be equipped with tools that enable the quantitative analysis of the evidencecollected in these cases.</p><p>In our laboratory, we develop analytical methods which can be used for both pre-blastand post-blast applications. However the main focus of this article will be on the postblastanalysis of ?home-made? devices (sometimes also referred to as ?improvisedexplosives? or ?improvised explosive devices (IEDs)?) constructed from low explosives.Inorganic home-made explosives employ vigorous oxidation/reduction chemicalreactions using strong inorganic oxidisers, such as nitrate, perchlorate or chlorate whichcan be obtained or refined from commercial sources. High explosives, such as nitratedorganic compounds (eg.TNT, RDX, PETN), are much more difficult to obtain becausetheir sale, storage and use are highly regulated.</p>Some of the analytical methods previously used for the analysis of inorganic explosivesinclude ion chromatography (IC), capillary electrophoresis (CE), scanning electronmicroscopy-energy dispersion X-ray, mass spectrometry, X-ray powder diffraction,infrared, atomic absorption spectroscopy and various spot tests. However, many of thesetechniques are not sensitive or specific enough for the analysis of inorganic anions orcations in explosive residues. We have found that the analytical techniques of IC and CEoffer complementary, sensitive and selective technology for determining a large range ofinorganic ions of relevance to the chemical identification of these types of explosives.

Topics

• impedance spectroscopy
• dispersion
• compound
• mass spectrometry
• chemical composition
• spectrometry
• quantitative determination method
• ion chromatography