Scientists have found a quick, accurate and highly sensitive process to reliably detect minute traces of explosives on luggage, cargo or travelling passengers.
The vapor detection technology accurately detects and identifies the vapors of even very low-volatility explosives in real time at ambient temperature and without sample pre-concentration.
Rather than searching for particle residue using a typical method like surface swipes or using pulses of air to dislodge particles for analysis, the system "sniffs" directly for explosives vapors, much the way bomb-sniffing canines do.
"We have demonstrated direct, real-time vapor detection for the low-volatility explosive compound RDX, which is used in many types of explosives," David Atkinson, senior research scientist at the Department of Energy's Pacific Northwest National Laboratory said.
Low-volatility compounds are those which release very small amounts of the explosive vapor typically at parts per trillion levels or lower, making it extremely difficult to detect.
The PNNL system easily detects vapors from a fingerprint-sized sample of RDX at levels below 25 parts per quadrillion.
"The system correctly identified the RDX vapor using selective atmospheric pressure chemical ionization with mass spectrometry," Atkinson said.
The approach involves pulling an air sample stream and ionizing it within a reaction region in an atmospheric flow tube.
The ionized sample moves to a mass spectrometer for ion detection and identification. These air samples need no heating or pre-concentrating. Analysis happens in about one second.
"The key part is ionization," Atkinson said.
"We tailored the chemistry to greatly enhance both ionization efficiency and selectivity, which results in the best possible detection," he added.
Only a limited number of ultra-sensitive detection methods have been found capable of detecting low-volatility explosive compounds at levels below parts-per-trillion. But these methods typically take much longer and require pre-concentration of the sample from the vapor phase.
The research is published in the journal Analytical Chemistry. (ANI)