Scientists develop peroxide sensor to combat terrorist attacks

Terrorists wanting to execute a 7/7 style attack will find it harder to carry out thanks to a new chemical detector developed by scientists.

Peroxide-based explosives are popular among terrorists as the ingredients to make them are easily available. The weapons used in the London bombings of July 2005 contained triacetone triperoxide - otherwise known as TATP. Shoe-bomber Richard Reid also had a concealed TATP trigger when he attempted to blow up an American Airlines flight in December 2001. Christmas Day bomber Umar Farouk Abdulmutallab also attempted to blow up a plane with a bomb that in part contained TATP.

During the trial of the 21/7 terror plot in London it was claimed that the hydrogen peroxide-based explosives one of the failed bombers made for the second attack on the capital's transport system had only been seen by the British authorities on one other occasion - July 7. 

Now Resat Apak and colleagues from Istanbul University, Turkey, have designed a sensor detecting peroxide-based explosives that could help avert future acts of terrorism and give British authorities the upper hand. The ultimate aim is to produce a hand-held version that can be used at points such as underground ticket barriers or airport security checks to prevent potential bombers from reaching their destination.

Their work is published in the Royal Society of Chemistry journal Analyst.

The team designed the first colourimetric, easy-to-use sensor that can selectively detect the peroxide-based explosives TATP and hexamethylenetetramine (HMTD); it can also be used beyond the lab. Both TATP and HMTD are extremely dangerous materials, which may lead to explosions under impact, friction, and temperature changes. Other spectroscopic methods for explosive detection use acid or enzyme digestion of the peroxide explosives before fluorimetric detection of hydrogen peroxide is carried out. However, these methods are often time consuming and vulnerable to interference from other strong oxidising agents; they also need to be carried out in a laboratory. 

In Apak's sensor, the sample is acid hydrolysed and passed over a Nafion membrane containing a copper-neocuproine complex that turns yellow if it detects the slightest amount of TATP or HMTD. The sensor would be ideal for post-blast analysis and identifying unknown materials or suspect packages confiscated by the police, says Apak.  It is cheap to make, easy to use and suffers no interference from other contaminants, such as nitro-explosives (TNT) or washing detergents. 

Nadir Serin, chief research engineer at the Scientific and Technical Research Council of Turkey, said: "The present technique can provide fast on-site inspection of TATP and HMTD explosives, which can be beneficial for giving quick-response against terrorist actions."
 
In future, a hand-held version of this device could see this sensor being used to check surfaces or airborne samples in airports, government buildings and other places at risk of being targeted by terrorists, says Apak. "Since TATP is essentially a kind of explosive used in terrorist attacks it is expected to be used by police criminological laboratories for on-site screening purposes where fast decision-making is of critical importance," he adds. 

References

Determination of peroxide-based explosives with copper(II)-neocuproine assay combined with a molecular spectroscopic sensor
Sule Eren, Ayem Üzer, Ziya Can, Timuçin Kapudan, Erol Erça and Reat Apak, Analyst, 2010
DOI: 10.1039/b925653a