New technology for tracking down builders of homemade bombs

Researchers in Australia have developed of a portable device to help track down builders of improvised explosive devices (IEDs).

The device will target IEDs such as homemade fertilizer bombs, which terrorists have planned to use in attacks on London in the past.

“IEDs have become a mainstay weapon for terrorists, resulting in an urgent need for new technology to identify and eliminate the sources of the explosives,” said Professor Paul Haddad from the University of Tasmania’s School of Chemistry.

“Quickly and reliably identifying the chemicals used in these crude but deadly bombs remains a major challenge to investigators.

“IEDs are often made with a diverse array of conventional, easy-to-obtain materials that require slow and painstaking analysis in the laboratory following an explosion.”

The new technology streamlines that process, quickly and accurately identifying the chemical composition of blast residues from IEDs in the field.

“We have developed a device that can identify inorganic IEDs through analysis of post-blast residues using portable capillary electrophoresis instrumentation and indirect photometric detection with a light-emitting diode,” said Prof Haddad.

The device consists of an instrument, about the size of a briefcase, based on a modified form of capillary electrophoresis, a mainstay technology for separating components in a mixture. In the study, researchers used it to identify major components of blast residues in less than 10 minutes.

IEDs constructed by terrorists often contain homemade explosives rather than high explosives, such as nitrated organic compounds (TNT), because of the relative ease with which the components used in their manufacture can be procured.

“Typically, IEDs comprise an explosive created from unrestricted materials and an initiation system involving an electrical charge and a detonator,” said Prof Haddad.

“Inorganic homemade explosives employ vigorous oxidation/reduction chemical reactions using strong inorganic oxidizers such as nitrate, perchlorate, or chlorate.”

Ion chromatography (IC) has been utilised for determining the main components of inorganic IEDs, with other techniques such as scanning electron microscopy-energy dispersion X-ray, X-ray diffraction, infrared, and atomic absorption spectroscopy, as well as wet chemical colour tests also being applied.

Prof Haddad and his team also used a process called capillary electrophoresis (CE). He said: “It is a viable alternative analytical technique, and several reviews have appeared recently describing the role of CE in forensic investigations using both capillary and micro-fluidic chip formats.

“CE and chip-based methods have been used for the screening of nitroaromatic explosives and inorganic species from explosives and explosives post-blast residues.

“Post-blast residues from inorganic IEDs can contain up to 15 different inorganic anions and 12 cations,” said Prof Haddad, “so a high-efficiency separation tool such as CE is necessary if these ions are to be used to identify the homemade explosive.”