Ehud Keinan displays a working prototype of his pen-shaped Peroxide Explosive Tester (PET). Photo courtesy of Erik Schechter.
Ehud Keinan, a chemistry professor at Haifa’s Technion-Israel Institute of Technology, faced airport security at its most vigilant when he flew into Baltimore/ Washington International just three weeks after the 9/11 tragedy. Personnel rummaged through Keinan’s luggage; had him turn on his laptop to make sure it was really a computer, and even confiscated his nail clippers. Yet a vial holding two grams of triacetone triperoxide (TATP), an improvised plastic explosive, went completely undetected.
First employed by Palestinian bomb makers, the highly unstable TATP — also known as the “Mother of Satan” — is difficult to detect by dogs and conventional hi-tech methods, such as nuclear quadrupole resonance. If the mild-mannered scientist had been a terrorist, and if he had whipped up a larger batch of TATP, he could have downed his connecting flight to Los Angeles, killing hundreds of passengers. Fortunately, Keinan has devoted many years of research to combating such threats.
At the McDonald’s in the terminal, the professor poured the white explosive powder on a table, and, as oblivious patrons lunched on Happy Meals, he demonstrated for an American government official a working prototype of his pen-shaped Peroxide Explosive Tester (PET). Three and a half years later, PET is ready for use by police and security agents; all Keinan needs now is a company to manufacture the device.
Though a former infantry officer and Yom Kippur War veteran, bomb detection technology has never held much interest for Keinan, who is now dean of chemistry at the Technion. “Most of my research has nothing to with explosives,” he says. “I work on drug discovery to treat asthma, cancer and ventricular fibrillation [an electrical disorder in the heart].”
Another passion is biomolecular computing, an interdisciplinary field of science emerging in 1994 which views biological systems like a PC — composed of hardware, software, input and output, except all four components are made of molecules instead of electrons. “It sounds like science fiction,” says Keinan, “but my dream is to make a dynamo of one molecule.”
Nevertheless, in 1987, the Technion professor got an urgent, midnight call from Yitzhak Kirson, now deceased, who was then chief chemist for the Shin Bet, Israel’s domestic intelligence agency. Kirson knew Keinan from their days at the Weizmann Institute of Science, in Rehovot, and trusted that, if called upon by his country, he would not refuse. The Shin Bet lab official proceeded to tell him of a new, worrisome explosive in the hands of Palestinian militants.
First discovered in 1980 in Hebron, TATP is made by mixing hydrogen peroxide, which can be bought in disinfectant form at the neighborhood pharmacy, and acetone, commonly found in paint thinners. The compound is helped along by an acid catalyst. “The liquid from your car battery or even lemon juice will do the trick,” notes Keinan. The easy recipe is not lost on the bomb makers: In just one raid in 1998, Palestinian Authority security personnel uncovered 800 kilograms of TATP in a Nablus garage.
However, Tal Hanan, security expert and C.E.O. of Demoman International Ltd., notes that TATP is hardly military grade. An unlucky tap or nearby cigarette can set it off, leading to fatal “work accidents” among terrorists and explosive ordinance disposal officers alike. Outside of Israel and the territories, the peroxide-based explosive is used — if at all — only as a detonator, and not the main charge, like in the hollowed out heel of “shoe bomber” Richard Reid.
Indeed, Ivan Oelrich, director of the Federation of American Scientists’ Strategic Security Project, wonders if pure TATP’s relative rarity is the only reason why security missed Keinan’s vial at the airport. If operating personnel are trained to look for it, existing portable technologies — such as ion mobility spectrometry, which identifies an explosive by its molecular mass, and nuclear quadrupole resonance, which looks for signature radio frequencies — should theoretically be able to pick up TATP, contend advocates.
“There are commercial detectors out there, but they have to pick up eight, very different types of explosives,” says Yehuda Zeiri, a chemist at Beersheba’s Ben-Gurion University who has worked with Keinan. “The question is one of sensitivity. How good are these devices at picking up TATP?” (As for dogs, they can be trained to pick up the scent of acetone in TATP, but in an urban environment, the animals can be distracted by household items that contain the chemical, says Hanan.)
For seven years, since the time Kirson first called him, Keinan volunteered his time to finding a cheaper and faster way to identify TATP than shipping off suspected material to the lab for analysis. Then, in the mid-1990’s, the Technical Support Working Group (T.S.W.G.), an umbrella organization comprised of 80 different United States agencies, including the F.B.I., C.I.A., and Federal Aviation Authority, made a welcome contribution of $100,000 to his research.
“The Clinton Administration wanted to help Israel deal with the increasing threat of suicide bombers,” notes Keinan.
Finally, in 2001, he created the first prototype of his Peroxide Explosive Tester, and just last month, he got an American patent on the third prototype. The device looks like an oversized pen with three levers at one end and a removable rubber cap at the other. The cap has a sticky surface designed to collect material; the levers release three solutions that wash over the cap when it is re-attached to the PET.
“The first solution is an acid that breaks down TATP into acetone and hydrogen peroxide,” explains Keinan. “The second contains a pigment that turns green when oxidized, and the third solution contains an enzyme that, when exposed to hydrogen peroxide, catalyzes oxidation in the pigment.”
The idea came from chemical immunology, says Keinan. Enzyme-linked immunosorbent assay (ELISA) uses hydrogen peroxide and pigment reactions to detect antibodies that are chemically bound to a specific enzyme.
PET is meant to be a cheap, disposable device. Keinan predicts that it will only cost $10 to $15, and once on the market, it will soon find its way into the pouch of every police officer or agent who deals with explosives: “We’re taking about hundreds of thousands of kits in the U.S. alone.”
The device already has some professional enthusiasts.
“A police officer reporting to an unidentified package is not going to be carrying a $10,000 device,” says Jimmie Oxley, a chemist at the University of Rhode Island. “That’s what’s so exciting about having a relatively inexpensive kit.”
Keinan is now negotiating with three companies that want to produce PET. The next step is to produce, together with Ben-Gurion University’s Zeiri, a long-range TATP detector. The two scientists, along with Ronnie Kosloff and Joseph Almog of the Hebrew University of Jerusalem, published an academic paper in January on the peroxide explosive. It turns out that TATP does not release heat when it detonates but rapidly decomposes into a gas whose force of expansion is lethal.
While such a discovery has no direct impact on detection, Keinan notes that “TATP becomes less of a threat the more we know about it.”