The Bomb Sniffer

Placed unobtrusively among the other notices that appeared in the columns of the Government publication Commerce Business Daily last week was an intriguing appeal. The U.S. Department of Transportation was calling for proposals to develop equipment that could spot and quickly identify "dynamite and other explosive vapors diffusing out of closed baggage." The implication of the notice was plain. Alarmed by the recent rash of bombings, on the ground and in the air, the Government is stepping up its efforts to encourage the design and manufacture of an effective bomb detector.

Fortunately, work on such a device does not have to start from scratch. Much of the know-how has already been accumulated by a Chicago lab called the Olfactronics and Odor Science Center, part of the Illinois Institute of Technology Research Institute. Under a $300,000 grant from the Federal Aviation Administration, the smell researchers have developed a prototype "bomb sniffer" that scents incriminating odors with all the dispatch of a highly trained bloodhound. In fact, the system has so impressed the Israelis that they have adapted and improved the design for their own harassed airliners, though they have not officially acknowledged the use of such a detector.

Detecting explosives by the vapors they give off is based on one of the stock-in-trade techniques of the modern scientific laboratory: chromatography, an analytical tool invented 64 years ago by an obscure Russian botanist named Mikhail Semenovich Tsvett. While trying to separate certain plant pigments, Tsvett discovered that they could be differentiated easily by letting a mixture wash down the side of a column of limestone. The pigments--each sticking to the surface in a characteristic way --flowed down the stone at markedly different rates, enabling Tsvett to distinguish them from one another. Over the years, chromatography has been refined to separate countless other substances--colorless as well as colored, vapors as well as liquids.

Golden Tube. The target of the chromatographic detective work performed by the bomb sniffer is the vapor from a chemical called ethylene glycol dinitrate (EGDN), one of the principal components of emissions given off by dynamite. With the aid of a small internal fan, the detector samples air in the vicinity of a suspect object and passes the vapors over a modern equivalent of Tsvett's limestone--a rough gold-plated copper surface that has a special affinity for EGDN. As the molecules adhere to it, their concentration increases. The special surface is then heated to 176DEG to 194DEG F., causing it to release its cargo of molecules. Conveyed by an inert gas, argon, into a tube made of pure gold, the molecules are concentrated even further. Finally, the telltale vapors are swept into the chromatograph itself. Adjusted to respond only to their known flow-rate, the detector's built-in electronic signaling mechanism quickly touches off an alarm. The system is so sensitive and accurate that it can detect EGDN vapors in air that carries only one part in a billion. Elapsed sniffing time: less than four minutes.

The project's chief engineer, Jay Fischman, is convinced that the device can be used not only to comb luggage compartments in aircraft but also to detect explosives in large office buildings, dangerous gases in mines, and other perilous material in anv locale where there might be blasts--accidental or otherwise. Hoping that such sniffers can be further improved, the FAA itself has not yet approved the detectors. It is also hedging its bets by sponsoring development of related devices like magnetic-anomaly detectors that can spot pistols and metal-encased bombs by the disturbances they create in magnetic fields. Indeed, only a few months ago, the FAA started installing the first of such devices at major airports and posted warnings to would-be terrorists and hijackers indicating that their weapons were under electronic surveillance. The posters had such a powerful effect that attendants began finding discarded pistols in airport trash baskets.

This file is automatically generated by a robot program, so reader's discretion is required.