FOR MOST PEOPLE, "forensic science" means cops and fingerprints and DNA analysis. All of that is still true, but these days forensic science encompasses much more. Some "whodunits" are more complicated and can involve an international cast of characters. Forensic science now also is used to verify and monitor compliance with such international agreements as the Nuclear Non-Proliferation Treaty and the Chemical Weapons Convention, and to learn whether a country is developing a clandestine nuclear weapons program.
The Laboratory's Forensic Science Center was established in 1991, and in its short life has become a leader in law enforcement, national security, defense, and intelligence applications. Using sophisticated analytical equipment, experts in organic, inorganic, and biological chemistry can determine the composition and often the source of the most minute samples of material. Lasers are also being used to "interrogate," or examine, a variety of materials.
The March 1994 issue of Energy & Technology Review described in detail the workings of the Forensic Science Center. It reported on the Center's excellent performance in a "round-robin" series of exercises with analytical chemistry facilities from around the world. The Center has done so well in these exercises over the years that it is no longer just a participant. Its staff also prepares samples for other laboratories to analyze. Following is an update on activities at the Forensic Science Center since early 1994.
What You See Is What You Get
Miniaturizing the GC/MS
Reduction in size does not mean a reduction in performance. The latest complete GC/MS unit is able to achieve the almost-perfect vacuum required for accurate analysis. It can run for 12 hours in the field, and, like a 500-lb bench-top model, can perform up to 200 operator-assisted analyses per day. While the operator sleeps, the turbomolecular pumping station refreshes the vacuum and other systems in the unit for another 12 hours of operation.
And how have they made this unit so small? When LLNL first took on the job of making a portable GC/MS system, very few off-the-shelf parts were available that, when assembled, would fit into anything the size of a suitcase. Almost all of the pieces that went into the first 68-kg unit were therefore designed and manufactured at LLNL. Meanwhile, miniaturization began to catch on in the GC/MS industry, so many of the components of the 32-kg version could be purchased from outside sources. While a few components of the latest 20-kg model had to be produced here, most have been purchased commercially, modified as necessary, and fitted together.
The unit's hydrogen supply for the portable gas chromatograph is typical of the shrinking components. The hydrogen supply in the 68-kg model weighed 14 kg. Today it weighs just 0.4 kg and still operates at 250 psi, just like its bigger bench-top brother.
The Center also has produced another unit whose parts can be replaced in the field. Parts are fitted together with O-rings, which facilitates repair, but more pumping capacity is needed to hold the desired vacuum. So there is still much work to do.
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