Explosive detection is a non-destructive inspection process to determine whether a container contains explosive material. Explosive detection is commonly used at airports, ports and for border control.
Explosive detection is a non-destructive inspection process to determine whether a container contains explosive material. Explosive detection is commonly used at airports, ports and for border control.
The use of colorimetric test kits for explosive detection is one of the most simple methods for officers, and widely used method for the detection of explosives. Colorimetric detection of explosives involves applying a chemical reagent to an unknown material or sample and observing a color reaction. Common color reactions are known and indicate to the user if there is an explosive material present and in many cases the group of explosives from which the material is derived. The major groups of explosives are nitroaromatic, nitrate ester, and nitramine explosives, as well as inorganic nitrate-based explosives. Other groups include chlorates and peroxides which are not nitro based explosives. Since explosives usually contain nitrogen, detection often is based around spotting nitrogenous compounds. As a result, traditional colorimetric tests have a disadvantage: some explosive compounds (such as acetone peroxide) do not contain nitrogen and are therefore harder to detect. [1]
Specially trained dogs can be used to detect explosives using their noses which are very sensitive to scents. While very effective, their usefulness becomes degraded as a dog becomes tired or bored.
These dogs are trained by specially trained handlers to identify the scents of several common explosive materials and notify their handler when they detect one of these scents. The dogs indicate a 'hit' by taking an action they are trained to provide — generally a passive response, such as sitting down and waiting.
The explosive detection canine was originated at the Metropolitan Police Department in Washington, D.C. in 1970, by then trainer Charles R. Kirchner. [2]
The explosive detection canine was first used in Algeria in 1959 under the command of General Constantine. [3]
Recent studies suggest that mass spectrometric vapor analysis techniques, such as secondary electrospray ionization (SESI-MS), could support canine training for explosive detection. [4]
This approach couples trained honey bees with advanced video computer software to monitor the bee for the strategic reaction. Trained bees serve for 2 days, after which they are returned to their hive. This proven system is not yet commercially available. Biotechnology firm Inscentinel claims that bees are more effective than sniffer dogs. [5]
Several types of machines have been developed to detect trace signatures for various explosive materials. The most common technology for this application, as seen in US airports, is ion mobility spectrometry (IMS). This method is similar to mass spectrometry (MS), where molecules are ionized and then moved in an electric field in a vacuum, except that IMS operates at atmospheric pressure. The time that it takes for an ion, in IMS, to move a specified distance in an electric field is indicative of that ion's size-to-charge ratio: ions with a larger cross-section will collide with more gas at atmospheric pressure and will, therefore, be slower.
Gas chromatography (GC) is often coupled to the detection methods discussed above in order to separate molecules before detection. This not only improves the performance of the detector but also adds another dimension of data, as the time it takes for a molecule to pass through the GC may be used as an indicator of its identity. Unfortunately, GC normally requires bottled gas, which presents logistical issues since bottles would have to be replenished. GC columns operated in the field are prone to degradation from atmospheric gases and oxidation, as well as bleeding of the stationary phase. Columns must be very fast, as well, since many of the applications demand that the complete analysis be completed in less than a minute.[ citation needed ]
Technologies based on ion mobility spectrometer (IMS) include ion trap mobility spectrometry (ITMS), and differential mobility spectrometry (DMS). Amplifying fluorescent polymers (AFP) use molecular recognition to "turn off" or quench the fluorescence of a polymer. Chemiluminescence was used frequently in the 1990s, but is less common than the ubiquitous IMS. Several attempts are being made to miniaturize, ruggedize and make MS affordable for field applications; such as an aerosol polymer that fluoresces blue under UV but is colorless when it reacts with nitrogen groups. [6]
One technique compares reflected ultraviolet, infrared and visible light measurements on multiple areas of the suspect material. This has an advantage over olfactory methods in that a sample does not need to be prepared. A patent exists for a portable explosive detector using this method. [7]
Mass spectrometry is seen as the most relevant new spectrometry technique. [8]
Specially designed X-ray machines using computed axial tomography can detect explosives by looking at the density of the items.. These systems that are furnished with dedicated software, containing an explosives threat library and false-color coding to assist operators with their dedicated threat resolution protocols. [9] X-ray detection is also used to detect related components such as detonators, but this can be foiled if such devices are hidden inside other electronic equipment. [10]
Adding marker substances (X-ray opacifiers) to commercial explosives is also an option. [11]
Specially designed machines bombard the suspect explosives with neutrons and read the resulting gamma radiation decay signatures to determine the chemical composition of the sample. The earliest developed forms of Neutron Activation Analysis use low-energy neutrons to determine the ratios of nitrogen, chlorine, and hydrogen in the chemical species in question and are an effective means of identifying most conventional explosives. Unfortunately, the much smaller thermal Neutron cross sections of carbon and oxygen limit the ability of this technique to identify their abundances in the unknown species, and it is partly for this reason that terror organizations have favored nitrogen absent explosives such as TATP in the construction of IEDs. Modifications to the experimental protocol can allow for easier identification of carbon and oxygen-based species, (e.g. the use of inelastic scattering from fast neutrons to produce detectable gamma rays, as opposed to simple absorption occurring with the thermal neutrons), but these modifications require equipment that is prohibitively more complex and expensive, preventing their widespread implementation. [12]
Silicon nanowire configured as field effect transistors have been demonstrated to detect explosives including TNT, PETN and RDX in sensitives superior to those of canines. [13] [14] The detection in this method is performed by passing a liquid or vapor containing the target explosive over the surface of a chip containing tens to hundreds of silicon nanowire sensing elements. Molecules of the explosive material interact with the surface of the nanowires and induce a measurable change in the electrical properties of the nanowire.
A detection taggant can be added when explosives are made to make detection easier. The Montreal Convention 1991 is an international agreement requiring manufacturers of explosives to do this. [15] An example is with Semtex, which now is made with DMDNB added as a detection taggant. [16] DMDNB is a common taggant as dogs are sensitive to it. In the UK, the relevant legislation is the Marking of Plastic Explosives for Detection Regulations 1996. [17]
The US Department of Justice warned in a National Institute of Justice publication, "Guide for the Selection of Commercial Explosives Detection Systems for Law Enforcement Applications (NIJ Guide 100-99)," about the ongoing trend of "bogus" explosives detection equipment being sold to unsuspecting consumers. The report mentions by name the Quadro Tracker, an apparent dowsing rod with a freely pivoting radio antenna rod with no functioning internal components. On August 8–9, 2005 the Naval Explosive Ordance Disposal Technical Division via the United States Counter-Terrorism Technology Task Force conducted testing on the SNIFFEX and concluded that "the SNIFFEX handheld detector does not work". [18]
…There is a rather large community of people around the world that believes in dowsing: the ancient practice of using forked sticks, swinging rods, and pendulums to look for underground water and other materials. These people believe that many types of materials can be located using a variety of dowsing methods. Dowsers claim that the dowsing device will respond to any buried anomalies, and years of practice are needed to use the device with discrimination (the ability to cause the device to respond to only those materials being sought). Modern dowsers have been developing various new methods to add discrimination to their devices. These new methods include molecular frequency discrimination (MFD) and harmonic induction discrimination (HID). MFD has taken the form of everything from placing a xerox copy of a Polaroid photograph of the desired material into the handle of the device, to using dowsing rods in conjunction with frequency generation electronics (function generators). None of these attempts to create devices that can detect specific materials such as explosives (or any materials for that matter) have been proven successful in controlled double-blind scientific tests. In fact, all testing of these inventions has shown these devices to perform no better than random chance… [19]
A number of fake dowsing rod-style detection devices have been widely used in Iraq and Thailand, notably the ADE 651 and GT200, where they have been reported to have failed to detect bombs that have killed hundreds of people and injured thousands more. [20] [21] [22] Additional names of fake dowsing rod style detectors include ADE101, ADE650, Alpha 6, XK9, SNIFFEX, HEDD1, AL-6D, H3TEC, PK9.
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a mass spectrum, a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures.
Electron ionization is an ionization method in which energetic electrons interact with solid or gas phase atoms or molecules to produce ions. EI was one of the first ionization techniques developed for mass spectrometry. However, this method is still a popular ionization technique. This technique is considered a hard ionization method, since it uses highly energetic electrons to produce ions. This leads to extensive fragmentation, which can be helpful for structure determination of unknown compounds. EI is the most useful for organic compounds which have a molecular weight below 600 amu. Also, several other thermally stable and volatile compounds in solid, liquid and gas states can be detected with the use of this technique when coupled with various separation methods.
Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture. In preparative chromatography, GC can be used to prepare pure compounds from a mixture.
Gas chromatography–mass spectrometry (GC–MS) is an analytical method that combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC–MS include drug detection, fire investigation, environmental analysis, explosives investigation, food and flavor analysis, and identification of unknown samples, including that of material samples obtained from planet Mars during probe missions as early as the 1970s. GC–MS can also be used in airport security to detect substances in luggage or on human beings. Additionally, it can identify trace elements in materials that were previously thought to have disintegrated beyond identification. Like liquid chromatography–mass spectrometry, it allows analysis and detection even of tiny amounts of a substance.
A taggant is any chemical or physical marker added to materials to allow various forms of testing or detection. Physical taggants can take many different forms but are typically microscopic in size, included at low levels, and simple to detect. They can be utilized to differentiate authentic product from counterfeits, provide identifying information for traceability purposes, determine mixing homogeneity and cross-contamination, and to detect dilution of proprietary products. Taggants are known to be widely used in the animal feed industry, plastics, inks, sheet and flexible explosives, and pharmaceuticals.
A detection dog or sniffer dog is a dog that is trained to use its senses to detect substances such as explosives, illegal drugs, wildlife scat, currency, blood, and contraband electronics such as illicit mobile phones. The sense most used by detection dogs is smell. Hunting dogs that search for game, and search and rescue dogs that work to find missing humans are generally not considered detection dogs but fit instead under their own categories. There is some overlap, as in the case of cadaver dogs, trained to search for human remains.
Demining or mine clearance is the process of removing land mines from an area. In military operations, the object is to rapidly clear a path through a minefield, and this is often done with devices such as mine plows and blast waves. By contrast, the goal of humanitarian demining is to remove all of the landmines to a given depth and make the land safe for human use. Specially trained dogs are also used to narrow down the search and verify that an area is cleared. Mechanical devices such as flails and excavators are sometimes used to clear mines.
An explosives trace-detection portal machine, also known as a trace portal machine and commonly known as a puffer machine, is a security device that seeks to detect explosives and illegal drugs at airports and other sensitive facilities as a part of airport security screening. The machines are intended as a secondary screening device, used as a complement to, rather than a substitute for, traditional X-ray machines.
Tracking refers to a dog's ability to detect, recognize and follow a specific scent. Possessing heightened olfactory abilities, dogs, especially scent hounds, are able to detect, track and locate the source of certain odours. A deeper understanding of the physiological mechanisms and the phases involved in canine scent tracking has allowed humans to utilize this animal behaviour in a variety of professions. Through domestication and the human application of dog behaviour, different methods and influential factors on tracking ability have been discovered. While tracking was once considered a predatory technique of dogs in the wild, it has now become widely used by humans.
DMDNB, or also DMNB, chemically 2,3-dimethyl-2,3-dinitrobutane, is a volatile organic compound used as a detection taggant for explosives, mostly in the United States where it is virtually the only such taggant in use. Dogs are very sensitive to it and can detect as little as 0.5 parts per billion in the air, as can specialised ion mobility spectrometers. Its presence allows more reliable explosive detection.
Ion mobility spectrometry (IMS) It is a method of conducting analytical research that separates and identifies ionized molecules present in the gas phase based on the mobility of the molecules in a carrier buffer gas. Even though it is used extensively for military or security objectives, such as detecting drugs and explosives, the technology also has many applications in laboratory analysis, including studying small and big biomolecules. IMS instruments are extremely sensitive stand-alone devices, but are often coupled with mass spectrometry, gas chromatography or high-performance liquid chromatography in order to achieve a multi-dimensional separation. They come in various sizes, ranging from a few millimeters to several meters depending on the specific application, and are capable of operating under a broad range of conditions. IMS instruments such as microscale high-field asymmetric-waveform ion mobility spectrometry can be palm-portable for use in a range of applications including volatile organic compound (VOC) monitoring, biological sample analysis, medical diagnosis and food quality monitoring. Systems operated at higher pressure are often accompanied by elevated temperature, while lower pressure systems (1–20 hPa) do not require heating.
Neutron detection is the effective detection of neutrons entering a well-positioned detector. There are two key aspects to effective neutron detection: hardware and software. Detection hardware refers to the kind of neutron detector used and to the electronics used in the detection setup. Further, the hardware setup also defines key experimental parameters, such as source-detector distance, solid angle and detector shielding. Detection software consists of analysis tools that perform tasks such as graphical analysis to measure the number and energies of neutrons striking the detector.
Explosives trace detectors (ETD) are explosive detection equipment able to detect explosives of small magnitude. The detection is accomplished by sampling non-visible "trace" amounts of particulates. Devices similar to ETDs are also used to detect narcotics. The equipment is used mainly in airports and other vulnerable areas considered susceptible to acts of unlawful interference.
The Fido explosives detector is a battery-powered, handheld sensory device that uses amplifying fluorescent polymer (AFP) materials to detect trace levels of high explosives like trinitrotoluene (TNT). It was developed by Nomadics, a subsidiary of ICX Technologies, in the early 2000s as part of the Defense Advanced Research Projects Agency's (DARPA) Dog's Nose program. The Fido explosives detector is considered the first artificial nose capable of detecting landmines in the real world. The device was named after its ability to detect explosive vapors at concentrations of parts per quadrillion, which is comparable to the sensitivity of a bomb-sniffing dog’s nose, i.e. the historical “gold standard” for finding concealed explosives.
Sniffex and Sniffex Plus are fraudulent explosive detection systems produced by Homeland Safety International.
High-field asymmetric-waveform ion mobility spectrometry is an ion mobility spectrometry technique in which ions at atmospheric pressure are separated by the application of a high-voltage asymmetric waveform at radio frequency (RF) combined with a static (DC) waveform applied between two electrodes. Depending on the ratio of the high-field and low-field mobility of the ion, it will migrate toward one or the other electrode. Only ions with specific mobility will pass through the device.
Autolycus or Sniffer was a submarine detection system designed to detect diesel-engined submarines from aircraft. It was designed to detect exhaust fumes from their diesel engines. Named after the mythical Greek, Autolycus, who took part in the search for the Golden Fleece, it was developed by the British during the early Cold War period. The first version of Autolycus was deployed on Avro Shackleton aircraft in the mid-1950s, with an improved version re-appearing in the mid-1960s.
Lorne Elias is a Canadian chemist, inventor, and a pioneer in explosives detection technology. He invented the explosives vapour detector, EVD-1, a portable bomb detection instrument deployed at international airports in Canada in the 1980s. He contributed to the field of explosives detection for over three decades, and is called the father of vapour and trace explosives detection technology.
Smell as evidence of disease has been long used, dating back to Hippocrates around 400 years BCE. It is still employed with a focus on volatile organic compounds (VOCs) found in body odor. VOCs are carbon-based molecular groups having a low molecular weight, secreted during cells' metabolic processes. Their profiles may be altered by diseases such as cancer, metabolic disorders, genetic disorders, infections, and among others. Abnormal changes in VOC composition can be identified through equipment such as gas chromatography-mass spectrometry(GC-MS), electronic nose (e-noses), and trained non-human olfaction.
Explosive vapor detectors (EVD) are explosives detection instruments whose principle of operation is the selective analysis of collected vapor samples from the air, in contrast to explosives trace detectors (ETD) which require the physical collection of particulate samples from surfaces. EVDs are not limited to explosives, and may also be used to detect narcotics and other illicit or dangerous substances such as biological agents or chemical warfare agents.
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