Detection of Explosives Residues on Aircraft Boarding Passes

Abstract

A prototype system for the detection of trace explosives residues on aircraft boarding passes has been developed. The desorption of explosives from the passes was achieved using short wave infrared radiation. The vapours produced were drawn into a triple quadrupole tandem mass spectrometer and were monitored in SRM mode. The infrared unit integrated with the tandem mass spectrometer has demonstrated limits of detection of less than 100 pg for the explosives studied (TNT, NG, PETN and RDX). A background study into the levels of explosives residues on used boarding passes was conducted by analysing over 20,000 boarding passes from a number of airports in England, America and Canada. Traces of explosives were detected on approximately 0.5% of passes analysed. Nitroglycerine contributed to the majority of the positive signals observed. All the signals observed were below 1 ng.

An automated unit has been developed after the success of the manual feed system, which incorporated the inclusion of a transport mechanism to move the boarding cards through the desorption window automatically. The desorption efficiency of the system was found to be between 70% and 100%, depending on the thickness of the card used for assessment. The unit was able to handle a throughput rate of 1000 boarding passes per hour and was able to detect between 10pg and 50pg of explosives residue from the surface of the card depending on the compound used.