Humble Ingredients for a Deadly Purpose

In the cookbook of home-brew bomb making, one of the simplest recipes is for a concoction known as TATP.

Its essential ingredients are acetone, the active component of nail polish remover, and industrial-grade hydrogen peroxide, a colorless, odorless liquid that looks like drinking water.

“All I have to do is take them in the restroom with a standard water bottle,” said Neal Langerman, president of Advanced Chemical Safety, a San Diego consulting firm. “I empty the water out, I mix them in the bottle, and before I’m done mixing them, the reaction has already occurred and the plane is in serious trouble.”

Getting to that point requires numerous steps. Some are as straightforward as shopping at Rite Aid or Home Depot. Others may require chemistry expertise and access to restricted industrial-grade supplies.

TATP teaches a simple lesson: Bomb making is neither as simple as some websites proclaim, nor as complex as security officials would wish.

It has been terrorists’ dark pursuit for decades, requiring knowledge so accessible that a Google search turns up the necessary instructions.

The government has spent more than $100 million researching ways to detect the myriad components of liquid explosives, but there is no equipment ready to deploy in airports. Some experts say there will never be a foolproof solution.

TATP, or triacetone triperoxide, is one of many explosives that authorities say may have been involved in the airplane bombing plot alleged Thursday by British authorities.

Other explosives include the highly volatile nitroglycerin, which Ramzi Ahmed Yousef -- architect of the 1993 World Trade Center attack -- used in a bomb aboard a Philippine airliner that killed one passenger in 1994. Terrorists in the Irish Republican Army used a mixture of ammonium nitrate and fuel oil, known as ANFO, to blow up cars in the United Kingdom.

Such mundane liquids as gasoline or alcohol could also be used as explosives when allowed to evaporate in an enclosed space.

The explosives vary widely in their power, but it doesn’t take much to create a catastrophe at 30,000 feet.

“You don’t have to do a lot of damage to an airplane to do a lot of damage to an airplane,” said Ted Postol, a physicist and professor of science, technology and national security policy at MIT.

British and U.S. investigators have found some indications that the 24 suspects in custody for the plot intended to use a hydrogen peroxide-based explosive, such as TATP.

This workhorse is a window into the world of do-it-yourself explosives.

Like all explosives, it blends a flammable liquid that serves as fuel with an oxidizer that provides the ignition. Terrorists who launched the London subway attacks last year used TATP. It has been a trademark explosive of Al Qaeda and routinely used by Hamas.

“Triacetone triperoxide has been quite a favorite,” said Edward M. Arnett, professor emeritus of chemistry at Duke University and a member of a National Academy of Sciences committee that investigated the threat of homemade bombs. “You don’t need to have a whole pile of it, and it gives a very sharp explosion.”

Some of the components are easy to get.

Acetone for TATP can be bought in large quantities as paint remover at a hardware store.

An appeal of liquid explosives is that their individual components can be transported safely and innocuously.

To an X-ray screening machine, they are indistinguishable from bottled water.

“Before this morning, it was very easy to get these liquids through screeners,” Langerman, of Advanced Chemical Safety, said. “People do it inadvertently all the time -- hair spray, acetone in nail polish remover, turpentine, gasoline.”

The hardest part of making such a bomb is mixing the chemicals -- and surviving.

That’s not a concern to a suicide bomber.

“If you don’t care about your life one way or another, it will get the job done,” Arnett said.

But not all ingredients of a bomb can be obtained at the local strip mall.

Hydrogen peroxide, for example, is found in hair dye and is marketed as an antiseptic, but household peroxide is too weak to be an explosive, experts say.

Highly concentrated hydrogen peroxide is usually sold to industrial customers, although UC San Diego Chancellor Marye Anne Fox, who led the National Academy of Sciences committee, said it was readily available from chemical supply houses. Those suppliers aren’t required to track their customers.

Even if terrorists were to acquire the right ingredients, there are numerous ways an attack could go wrong.

In the Philippine airliner case, the only passenger killed was a Japanese man sitting above the bomb. Ten others were injured, but the pilots managed to steer the plane to a safe landing.

Jimmie C. Oxley, a University of Rhode Island chemistry professor and explosives expert, said she doubted TATP was strong enough to bring down a plane without added strength from a detonator.

“It will go bang, but it won’t be the kind of explosion that would punch a hole in the side of the plane,” she said.

Terrorists are turning to liquid explosives because the Transportation Security Administration has been focused on detecting solid explosives, such as the powerful plastic weapon Semtex.

The current screening system relies on the fact that explosive molecules are very negatively charged, “which means they’re sticky,” said Tony Fainberg, who spent seven years with the TSA, Department of Homeland Security and Federal Aviation Administration. “They adhere to bits of dust and particles of skin.”

Airport screeners can identify them by analyzing residue on filter paper used to swab carry-on bags or blown off travelers by puffs of air in specialized booths.

Those methods don’t work for liquids.

Homeland Security Secretary Michael Chertoff said Thursday that his department had done “quite a bit of work on liquid explosives.”

The technology to detect them exists. Droplets dabbed on starch-iodide paper can identify peroxide the way litmus paper recognizes an acid, Langerman said.

Opening every bottle of liquid, however, is impractical in an airport. Vapors from flammable liquids leak out of their containers, and screeners can look for them inside suitcases using commercial chemical sensors that could be adapted for airports, he said. Still, authorities recognize that there will always be chemicals that evade their newest sensors.

“Because the threat is always evolving and changing, it’s a continuous effort to stay ahead,” said David M. Stone, former head of the Transportation Security Administration. “We’re never going to be in a position where we’ve fully met the threat.”

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(BEGIN TEXT OF INFOBOX)

Detecting liquid explosives

Liquid explosives are generally harder to detect than solid explosives. New machines that analyze the contents of bottles are being tested, but most airports still rely on so-called trace detection units.

Trace detection

An object is wiped with a cloth, which is placed inside a machine and analyzed for explosives.

Particle detection

Air blown onto a person releases microscopic particles, which are sucked into a machine and analyzed.

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Other methods of detecting explosives

Radio frequency identification uses electronic tags and radio frequency technology to track and identify items.

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Millimetric wave imaging bounces high-frequency signals off people to measure temperature differences and identify objects hidden under clothing.

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Quadrupole resonance, related to the magnetic resonance imaging used in hospitals, uses low-intensity radio wave pulses to identify even small amounts of plastic explosives.

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Raman technology uses lasers to analyze unknown substances for their chemical ‘fingerprints.’

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Source: GE Security. Graphics reporting by Scott Wilson

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Times staff writer Nicole Gaouette in Washington contributed to this report.