What's more, researchers can now predict how quickly VX decays when it is sprayed on concrete. VX attacks the body's nervous system by interfering with the normal transmission of chemicals that help control nerves, muscles and glands.
Through funding from the U.S. Army and the Department of Energy, INEEL researchers are supporting environmental restoration and national security activities by designing new instruments that can identify chemicals quickly and accurately. INEEL specializes in analyzing chemicals on the surfaces of common materials such as soils and plants.
Using a prototype IT-SIMS (ion trap secondary mass spectrometer), researchers discovered that the chemical makeup of concrete reacts with VX and causes it to break down. How quickly the chemical weapon decomposes depends on the temperature of the environment-the hotter the better. Determining the relationship between VX degradation on concrete and ambient temperature is a significant advance. Such information could help governments make better decisions about how to protect their people in the event of a VX attack. A cover article featuring this research appears on the Nov, 15, 2002, Environmental Science and Technology Journal.
VX is easily absorbed through skin and eyes, and exposure to a tiny fraction of a gram can be lethal. It's important to be able to detect traces of the chemical on concrete, and to understand how long it will hang around, because concrete is so common. Although VX has been banned for use through the Chemical Weapons Convention, and most countries are destroying their stock of the chemical, it remains of interest because of possible use by terrorist groups.
At first, the research team just wanted to prove that its prototype IT-SIMS instrument could accurately detect VX on concrete. The test was a success, but when the team looked at the spectra again later on, team members saw unexpected changes.
"At the time, we didn't know VX would degrade on concrete," said INEEL chemist Gary Groenewold. "Then we realized that we were looking at the spectral fingerprints for VX degradation products." Each chemical has its own unique, signature spectra-similar to that of a fingerprint.
Concrete, composed mainly of calcium carbonate and sand, has a high basic pH (10 or higher), and this pH enables it to neutralize the VX nerve agent. At a comfortable 24 degrees Celsius (75.2 degrees Fahrenheit), VX will degrade to 1 percent of its original concentration within 15 hours, and dwindle to a mere 10-millionth of original concentration within 50 hours.
Other factors such as humidity or differences in concrete composition also play a role in how quickly VX will degrade, and still need to be studied. Additionally, the team used ground up concrete for its tests because the powder is easier to sample for analysis than chunks of concrete, but analyzing intact concrete is the next step.
IT-SIMS is particularly suited to applications such as chemical weapon agent detection because such chemicals are designed to be both adsorptive and persistent-to stick to any and all surfaces and stay there. The sensitivity of the IT-SIMS instrument for detecting organic chemicals that tightly bind to surfaces is unparalleled, said Groenewold, and "it's safe to say that there is no off-the-shelf instrument available that can work this well."
The IT-SIMS instrument detects VX by bombarding a sample of contaminated concrete with a large atomic projectile to lift or "sputter" off molecules adhering to the concrete. The sputtered molecules, called secondary ions, retain the chemical characteristics of the chemical warfare agent stuck to the surface of the concrete. The secondary ions are filtered by mass and then counted. That data is displayed as a spectra (a bar graph that plots the number of ions versus their mass) that researchers then use to identify the chemicals.
One advantage of INEEL's IT-SIMS is that researchers trap secondary ions and then use precisely chosen electromagnetic frequencies-called tickle voltages-to fragment the ions into still smaller pieces, allowing them to achieve incredible specificity in their chemical analysis. A second advantage of the instrument is the choice of bombarding projectile-a large rhenium/oxygen molecule called a perrhenate ion. A large projectile is more effective at knocking off ions for analysis.
The design and fabrication work, chemical agent degradation product and precursor testing is being carried out at INEEL facilities. Testing of live chemical warfare agents is being conducted under controlled conditions at the U.S. Army West Desert Test Center chemistry laboratory, Dugway Proving Ground, Dugway, Utah. INEEL's IT-SIMS is slated to be used to assist the Army during the decommissioning of the former VX production plant in Newport Indiana, and has been used to support analysis for other chemical weapons decommissioning sites.
This research was supported by the U.S. Army Chemical Materiel Destruction Activity, Non-Stockpile Program, Defense Threat Reduction program.
The INEEL is a science-based, applied engineering national laboratory dedicated to supporting the U.S. Department of Energy's missions in environment, energy, science and national defense. The INEEL is operated for the DOE by Bechtel BWXT Idaho, LLC.
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