Briefcase picks up bomb residues
Scientists have developed a new tool to help counter-terrorist investigators quickly track down the people responsible for detonating homemade 'fertiliser' bombs used in attacks such as the 2002 Bali bombings.
These crude but effective explosives can be made from a range of easily purchased chemical components, such as ammonium nitrate, which is commonly used as an industrial fertiliser.
The Australian government asked Professor Paul Haddad and his colleagues from the University of Tasmania to develop a fast and portable system for analysing the composition of blast residues from these explosions in the field.
Figuring out the composition of the bombs can help investigators identify the culprits.
"What we're doing is fingerprinting the type of explosive that's used," Haddad says.
"The idea is that if you can identify the chemicals used in the explosive quickly, then you can look at who has just bought a large amount of it."
Their system is about the size of a briefcase, and can analyse the components of a bomb residue within 10 minutes, Haddad and colleagues report in the latest issue of the journal Analytical Chemistry.
The device is smaller, faster and more comprehensive than other similar tools, Haddad says.
It uses a routine piece of technology called capillary electrophoresis, which the Tasmanian group modified to fit into a small space.
To use it, investigators would take a swab of blast residue, dissolve it in water and pour it into a small vial in the device.
The electrophoresis system separates the bomb ingredients on the basis of their size and electrical charge, and delivers the results to an attached laptop.
The instrument can detect 27 chemicals known to be present in residues from bombs constructed from ammonium nitrate and fuel oil mixtures, gunpowder, and mixtures of chlorate, perchlorate and sugar, the authors say.
These include 15 negatively charged ions: acetate, benzoate, carbonate, chlorate, chloride, chlorite, cyanate, fluoride, nitrate, nitrite, perchlorate, phosphate, sulfate, thiocyanate, thiosulfate.
The unit detects 12 positively charged ions: ammonium, monomethylammonium, ethylammonium, potassium, sodium, barium, strontium, magnesium, manganese, calcium, zinc and lead.
"We've come up with an improved method for detecting the components of these explosives," Haddad says.
"No matter what the bomb is, we'll know what it was made of."