An Australian team of researchers has developed a better way to screen people who might have been making improvised explosive devices (IEDs).
Organic Peroxide Explosives (OPEs) are frequently used by terrorists, because they can be made from readily available materials and mixed in a domestic kitchen.
OPEs have been used in IEDs in terrorism events including the 2015 Paris attacks, the 2016 Brussels attacks, the 2017 Manchester bombing and the 2019 Sri Lanka bombings.
Swabs can pick up tiny traces of OPEs on skin, so it’s possible to screen for people who’ve carried or made OPEs. This is often done at random in airports.
But the current screening method also picks up hydrogen peroxide, which is used in a variety of common household products including cleaning agents, hair dyes and nail polish removers.
Research published in Analytica Chimica Acta has pointed to a new, more specific, technique, which avoids the problem caused by hydrogen peroxide, so could end up incorporated into standard airport and security screening.
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“I was thinking that there should be a more portable, inexpensive and rapid screening method, which can be employed easily by anyone – it doesn’t need to be a specialised or skilled person,” says lead author Dr Parvez Mahbub, an adjunct fellow at Victoria University in Melbourne.
Mahbub and colleagues’ technique uses chemiluminescence: molecules that glow when they react with certain chemicals.
After swabbing skin, the swabs are treated with a “miniscule” amount of sulphuric acid, which removes any hydrogen peroxide.
Then, a process called flow injection analysis with chemiluminescence detection allows the incriminating molecules in OPEs to show up.
“Within 15 seconds, we will have a result. So it is quite fast,” says Mahbub.
So far, the researchers have showed that the process works when taking swabs from pig skin – a common analogue for human skin.
“To do it on humans, you need volunteers, as well as ethical clearance, as well as funding,” says Mahbub.
His team is negotiating with funding agencies to continue the tests on people, as well as aiming to develop “version two” of the technology.
“I’m trying to replace acid with an advanced light source, for example LEDs, which might make it even more safe,” says Mahbub.
This would convert the acid step into a simple button press. According to Mahbub, this will make the process more portable and faster, as well as safer.
The testing method is still some years away from widespread use, but Mahbub says that it’s fast and simple enough that it could one day become a compulsory part of airport screening.
“It will add some more extra functionality in terms of the ability to screen – because we would like to see which sample is coming from an explosive and which sample is just coming from a household product.”
