Aviation securityIncreasing the sensitivity of airport security screening

The latest episode in the American Chemical Society’s (ACS) Global Challenges/Chemistry Solutions podcast series reports a simple way to improve the sensitivity of the test often used to detect traces of explosives on the hands, carry-ons, and other possessions of passengers at airport security screening stations.

An ACS release reports that the new podcast, based on a report by Yehuda Zeiri, Ph.D., and colleagues in ACS’ Journal of Physical Chemistry C, is available without charge at iTunes and from the ACS/globalchallenges Web site.

In the new episode, Zeiri explains that most tests for traces of explosives begin by rubbing a swab made from glass fiber, Teflon, or cotton over the suspect material. Analysis of the swab in a detector alerts agents to any explosive residues on the swab material.

Common explosives like TNT are solids at room temperature, so the best way to detect them is to search for particulate traces that rub off onto clothing and luggage. To help security agencies prevent attacks more successfully, the researchers studied how explosive particles adhere to surfaces and how they could improve the swabs so they would pick up even smaller amounts of explosives.

The scientists used a so-called atomic force microscope to measure how much the explosive particles stuck to different self-assembled monolayers. They concluded that swab fabrics could be improved to collect smaller amounts of explosives by peppering them with hydroxyl, phenyl and amine functional groups. They believe that such additions could enhance the binding between the swab and irregularly shaped explosive particles.

— Read more in Irena Efremenko et al., “Adsorption of Explosive Molecules on Human Hair Surfaces,” Journal of Physical Chemistry C 111, no. 32 (25 July 2007): 11903–11 (DOI: 10.1021/jp071616e)