The threat of homemade explosives (HMEs) is not new. From the Oklahoma City bombing in 1995, to the “shoe bomber,” London underground bombings, “underwear bomber,” and attacks in Paris and Brussels in the 2000s, the threat is ever changing. Not only do post-incident crime scenes present danger to responders until secondary devices have been ruled out, but also makeshift laboratories where the bombs are made. Handheld explosives trace detection (ETD) equipment can help responders quickly determine on-scene threats, like Triacetone Triperoxide (TATP) and react appropriately and expediently.TATP has been used in bombing and suicide attacks, including the 2016 Brussels and 2017 Manchester Arena bombings. It was also used in the explosion that preceded the 2017 terrorist attacks in Barcelona. Terrorists frequently use this chemical because it is relatively easy to make using household supplies. As such, TATP is often produced in makeshift laboratories found inside apartments, homes, or other residential structures. Evidence of TATP manufacture may include glassware such as beakers or flasks, mixers, filtration systems, and distillation equipment. TATP is often kept cold to increase its stability, so ice baths or refrigerators may indicate production. Its instability makes it very dangerous to responders investigating makeshift laboratories. Even trace level quantities can be dangerous if detonated.
TATP Chemical RelevanceGiven the instability and volatility of TATP, it is important for responders to know what to look for and how to approach explosion sites or suspected makeshift laboratories where the chemical has been found or handled. TATP appears as a white crystalline powder with a bleach-like odor. Shock, static, sparks, heat, and friction can cause detonations. Large volumes of easily obtained chemicals such as acetone, sulfuric acid, or peroxide-based bleaching formulations can be indicators of TATP production (Figure 1):
- Acetone is found in nail polish remover or paint thinner.
- Sulfuric acid is present in car batteries and acidic drain cleaners.
- Cosmetic or wood bleaching solutions can be a source of concentrated hydrogen peroxide.
Using Explosive Trace DetectionIn a suspected bomb-making environment, both surfaces and containers may be investigated using particle or vapor sampling procedures. Responders should always be aware of the possibility of booby traps or secondary devices, and the dangers of entering homemade laboratories. Numerous technologies can be used for detection, including colorimetric kits (using wet chemistry and color change indicators), Raman spectroscopy (confirmatory tool), ion mobility spectrometry (IMS), and chemiluminescence. The data provided in this article demonstrates TATP detection using a chemiluminescence-based ETD. Detection of trace explosive signatures results from either directly collecting trace quantities of explosive particles, or by sampling vapor that emanates from an explosive source. Particulates can be solid explosive residue or non-explosive particulates contaminated with explosives, with surface contamination occurring in two primary scenarios:
- When explosives are handled or moved, small particulates of explosives can become suspended in the air and settle onto surfaces.
- Surface contamination can also occur through direct contact with explosive-contaminated or contact with another explosive-contaminated surface. Primary transfer occurs when bulk explosive materials (a quantity that can easily be seen) come into direct contact with a surface, such as a person’s hand when handling explosives. Secondary transfer occurs when a surface that was contaminated by primary transfer comes into contact with a second surface. An example of secondary transfer would be a transfer of explosive materials to an identification card, door handle, cellphone, etc.
SummaryTATP is a common threat used by terrorists, because it can be made from easily available household supplies and produced in makeshift laboratories. This unstable chemical is dangerous to first responders in bulk (visible) quantities. Responders should be aware of the unique signs to look for when TATP manufacturing is suspected and understand that trace (invisible) quantities of TATP can be detected by ETDs using particle (swipe) or vapor sampling methods.
Ryan Holland, product manager for explosives and narcotics detection at FLIR Systems, has over 15 years of experience in the development of the Fido X Series sensor (U.S. patent #6,558,626) for detection of ultra-trace levels of explosive vapor and particulates. He has served as a research scientist on a variety of projects related to trace detection of explosives, including landmine detection, improvised explosive device (IED) detection, detection of explosives in marine environments, ageing and chemical transformation of trace explosives residues in the environment, the characterization of explosive chemical signatures associated with IEDs and persons involved in the fabrication of explosive devices, development of forensics tools for use by warfighters in battlefield environments, detection of explosives using canines, and sensor algorithm development.
Dr. Mark Fisher, scientist at FLIR Systems, holds a Ph.D. in physical chemistry from Oklahoma State University. He has been instrumental in the development of the Fido X Series sensor (U.S. patent #6,558,626) for the detection of ultra-trace levels of explosive vapor and particulates. He has served as technical lead on a variety of projects related to trace detection of explosives, including landmine detection, improvised explosive device (IED) detection, detection of explosives in marine environments, ageing and chemical transformation of trace explosives residues in the environment, the characterization of explosive chemical signatures associated with IEDs and persons involved in the fabrication of explosive devices, development of forensics tools for use by warfighters in battlefield environments, detection of explosives using canines, and sensor algorithm development. He has an extensive background in the development of methods and hardware for sampling of trace chemical signatures in gas and condensed phases, including development of noncontact methods for sampling trace particles from surfaces.