Devices could help identify explosives used in homemade bombs

Technology could help police and forensic scientists to quickly identify explosives used in terrorist attacks.

By Karina Toledo

Agência FAPESP – Two devices developed at Australia’s University of Tasmania could help police and forensic scientists to quickly identify explosives used in homemade bombs for terrorist attacks.

One of them, aptly named Scantex, analyzes materials in just 60 seconds. Small enough to fit into a suitcase, the device was developed for use at airports, sports events, shows, post offices and other locations where there is a large number of people or objects to be tested and identification is crucial.

The other device — CEScan — is a little larger but still portable and does the job in 20 minutes. The idea is to use the equipment to identify the ingredients used in makeshift bombs at crime scenes after an explosion, information that could lead the police to the perpetrators of the crime.

Technology for the separation of molecules and chemical analysis was one of the highlights of the São Paulo School of Advanced Sciences on Bio-organic Chemistry, an event held in Araraquara from June 30 to July 5 under the auspices of this FAPESP funding line.

“Post-explosion analysis is more complex. In addition to the ingredients of the bomb, the samples have vestiges of a series of other materials found in the environment. So the equipment must be capable of separating several types of compounds and it takes more time,” explained Paul Haddad, director of the Australian Centre for Research on Separation Science (Across) at the University of Tasmania and coordinator of the study.

The pre-explosion analysis evaluates a smaller number of substances and must be quick, to prevent lines from growing long at airports, for example. The process is entirely automatic and user-friendly enough to be operated by people without experience.

According to Haddad, the equipment used currently in airports can identify only so-called “highly explosive” substances such as nitroglycerin, trinitrotoluene (TNT) or Semtex – all very powerful and restricted.

“Obtaining this type of substance is very difficult, you cannot walk into a store and buy it. For this reason, terrorists tend to use improvised explosives, made of materials like fertilizers, pesticides, oil and sugar,” explained Haddad.

Among the most used substances are inorganic substances such as ammonium nitrate and potassium chloride, both used in agricultural practice. This type of bomb was used in Al Qaeda’s attacks on Madrid trains on March 11, 2004, which killed 191 people and wounded 1,800.

In Oklahoma City, a 1-ton makeshift bomb was used in the terrorist attack that killed 168 people – 19 of whom were children – in 1995. Other examples are the terrorist bombings in Bali, Indonesia in 2002 and the recent case of the attack on the Boston Marathon in the United States, which left 3 people dead and 144 wounded.

“Since this type of explosive is less potent, the bomb must be large in order to be damaging. They tend to place them in backpacks, vans or even in a truck parked in front of the targeted building. The sooner the police can identify the substance used, the quicker they can track who bought suspect quantities of that material and reach the authors of the attack,” explained Haddad.

In the case of the explosion in Bali, said Haddad, the police took almost four weeks to identify the explosives through traditional methods.

How it works

Both Scantex and CEScan use a method for molecule separation known as capillary electrophoresis (CE). In pre-explosion analysis, a sample is obtained by wiping a piece of cotton on the hands or luggage of the person to be tested. In the post-explosion analysis, the same procedure is done at the site of the attack.

The samples are then placed in a solution, and the liquid goes through a small glass tube with a diameter of approximately 75 microns – equivalent to the width of a hair. Within the tube, there is an electrolytic solution. An approximately 30,000-volt electric current is triggered and passes through the capillary, taking with it the charged molecules.

“We look for ions like chlorate, sulfate, perchlorate and nitrate. If it has a negative charge, all of them will move to the positive pole, but at different speeds. They will reach the other side at different times, and this will allow for identification of what’s in the solution,” Haddad commented.

This analytical technique has applications that go beyond counterterrorism. According to Haddad, it could be useful in drug tracking or controlling food quality, helping to identify pesticides.

It is also interesting for any type of industry that needs chemical analysis, such as pharmaceuticals. “Instead of taking a sample and sending it for analysis at a laboratory, the equipment can be taken to the production site, and the result is available much quicker,” he said.

The US$ 3.5 million study was funded through a partnership between the U.S. and Australian governments. To date, only prototypes have been built, which are being tested by the Australian police.

“We are negotiating with companies interested in building and selling equipment. Only the hardware of the devices has been patented. The necessary information for applying the method, like materials and voltage, are published and can be reproduced in any part of the world. We are attempting to earn money and resolve the problem,” affirmed Haddad.