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Rapid Chemistry When It Matters Most

Posted by | April 28, 2010

The last time I went to Nevada, I stood on the edge of an enormous open-pit mine at noon. The whistle blew. Then the pit erupted in explosive power enough to make the Earth rumble.

“I always like to watch it,” said the geologist giving me the tour. “It looks like the rocks down there just get ‘fluffy’ when they are blasted apart.”

We had visited the floor of the great pit, picking up rocks, squinting at them through hand-lenses, and hammering on them. The strong Nevada wind was blowing all day and by the end of it all I was filthy, to say the least.

Although I don’t know for sure, if I had gone directly from the mine to an airport, I might not have been able to board a commercial plane. The reason is that some airports employ “sniffers” that can detect explosives, even in trace amounts.

Roughly speaking, there are two kinds of sniffers. First, there are the type with wet noses you can train with dog-treats to signal the presence of a wide range of materials, from drugs to explosives to produce.

Second, there are sniffers that are man-made devices that are also exquisitely good at detecting just a few particles of various materials for which they are designed and calibrated. The second, mechanical type are not as cute as beagles, to be sure, and they don’t move around a busy airport lobby on their own four feet, following their noses. But, on the positive side, the man-made sniffers don’t get pooped out in mid-afternoon like dogs (and me).

Unfortunately, no sniffers of either kind appear to have been on duty last Christmas when the “underwear bomber” tried to blow a jetliner out of the skies over our Midwest. If the authorities had used sniffers on Umar Farouk Abdulmutallab, I’m told they would have had a good chance of detecting the explosive before he was allowed to board the first plane of his long travels.

I spoke recently about all this with Prof. Herbert Hill of Washington State University. For many years now, he has been in the field of ion mobility spectrometry (IMS) (that’s the fancy term for the broad set of lab devices that can include the man-made sniffers in airports today).  IMS works by giving an electrical charge to small particles, and then watching how they move from one charged plate to another.

Hill is an analytical chemist: somebody who wants to identify chemical samples. He got started in his field partly due to his interest in being able to detect tiny amounts of pesticide in stream water or contamination in drug manufacturing. IMS is his favorite analytic device, his “baby.”

Hill’s laboratory is made of room after room with IMS devices, each one a research unit, not a commercial device, and each set up for a different purpose. While not as interesting as beagles to me (I’m a dog person – what can I say), the devices are amazing in what they can do. And they have come a long way.

When Hill first worked with IMS, it took about 4 hours to get a full reading on a single sample. It now takes less than a second – which is why IMS has become so useful in real-world applications like airports. Clearly, in the day-to-day world, we need systems that work fast, and that make as few errors, one way or another, as possible.

It’s interesting to note that what counts as an “error” is complex. If an IMS sniffer (or a beagle, for that matter) pulls a geologist out of an airplane line just for having been around explosives, that’s a “good hit” in the sense that the sniffer is legitimately detecting explosives. But it’s not usually useful security information, and is likely to delay not just one rock-head but potentially a whole planeload of people.

As you might guess, Hill’s former students are in industry, government, and Homeland Security. Some of them are likely laboring today to try to keep our airplanes in the skies.

Even though they could pull me aside with their sniffers, I wish them the very best.