Washington, June 13 : Security and law enforcement officials may soon get a new technique to fight terrorism - a universal detection system that can monitor the air for virtually all of the major threat agents that could be used by terrorists.
Currently underdevelopment by a team of Lawrence Livermore National Laboratory (LLNL) scientists and engineers, this system called Single-Particle Aerosol Mass Spectrometry, or SPAMS, has already been tested in laboratory and field experiments.
And now, the researchers have shown that it is now possible to almost simultaneously detect four potential threat materials - biological, chemical, explosives and radiological - along with illicit drugs.
"We believe SPAMS is the only detection instrument that can autonomously detect multiple types of threat agents and trigger alarms within less than a minute. What sets this work apart is that we did our experiments with all these types of threat agents within minutes of each other without reconfiguring the SPAMS instrument," said Matthias Frank, an LLNL physicist and one of the paper's co-authors.
It was just last year that the researchers announced that their instrument could perform as a three-in-one detection machine, monitoring the air for biological, chemical and explosive agents.
After that, the researchers kept on improving upon it to add capabilities of detecting illicit drugs and powders from radioactive metals.They developed the software capability to help in detecting metal powders and the algorithms to help detect all four threat agents at one time.
According to the paper's lead author, LLNL physicist Paul Steele, three factors are particularly important in developing a detection machine like SPAMS: sensitivity, false alarm rate and response time.
"What we have accomplished is to make an instrument that is very sensitive, with a very low false alarm rate, but very fast. That's unique. Other systems that are just as fast and sensitive have higher false alarm rates," said Steele.
The researchers tested SPAMS in lab experiments against four types of materials terrorists might use -- spores of a non-pathogenic strain of Bacillus anthracis (other strains of this bacteria cause anthrax); diethyl phthalate (a nerve agent surrogate), natural cobalt powder (a surrogate for Cobalt 60 and other radioactive metals) and trinitro-1,3,5-triazinane (RDX, a high explosive). It was also tested against pseudoephedrine (used to synthesize methamphetamine).
In single- and multiple-agent tests, SPAMS accurately identified each substance and set off the correct alarms within an average of 34 seconds after their release against a background of air as the system was open to the environment. All of the measurements were achieved within 26 to 46 seconds after the compounds' release. However, they used natural cobalt powder and RDX, and a non-pathogenic strain of Bacillus anthracis and RDX in the two multiple-agent tests.
In field experiments, SPAMS has been tested at San Francisco International Airport. As part of a background study, the mass spectrometry system analyzed the air for about seven weeks in 2004-05, recording data, though it lacked the capability to set off alarms. Later, the system records were analyzed in the lab to evaluate whether any alarms, false or real, would have been triggered.
It was found that while a few particles showed up as spores among the almost one million particles studied, there were so few that no alarms would have been triggered.
"What distinguishes SPAMS from other instruments is the high-quality information we receive from the instrument in the form of single-particle mass spectra. As a result, we get specificity and many fewer false alarms. We're very enthusiastic about how the system is working, not only in the lab but also in field tests," said Frank.
The researchers are planning to develop ways in future to make the SPAMS machine smaller and less expensive.
The study is published in the latest edition of Analytical Chemistry, a semi-monthly journal published by the American Chemical Society.