Application of Chemical Instruments to a Bomb Site - Case Study Example

Application of chemical instruments to a bomb site On an unassuming Saturday afternoon at London, an explosion went off inside a cinema hall at around 2:00 pm in the afternoon. Following the explosion, two more explosions, racked the neighborhood between 2:00 pm and 2:30 pm. Of these explosions, one happened at the Scout Bar and the other at Eat Out restaurant. Given the fact that it was weekend and the time during which the explosions happened coincided with the fact that it was peak hour for Saturday revelers. The explosions therefore ended up killing 239 people, of which 72 were tourists. Hundreds more were left injured. Ambulances and the police rushed to the scene to coordinate the chaos and to help the injured to the hospital. Fire engines arrived at the explosion scene to put out the burning buildings and the forensic police arrived shortly after to begin their investigation. Initially, it was thought that the gas cylinder of a nearby restaurant had exploded, but further investigation suggests that it was acts of terrorism by suicide bombers. After the explosion, preliminary investigations discovered the fact that an approximate amount of 3 to 4kg of trinitrotoluene (TNT) was the cause of the explosion at the 89 Forum Cinema Hall. This was also the second largest explosion of the three. The explosion took place because of the fact that the TNT was packed well within the length of the PVC pipe of 55mm diameter sewn inside a nylon jacket. Based on this evidence, it was possible for one to confirm the fact that investigation found small shreds of nylon fabric at the site of the blast. Also, it was found that the blast did not create a crater or extrapolation of spatter, indicative of the fact that the bomb blast took place, at least two to three feet above ground level. This makes it clear the blast itself was the work of a suicide bomber. The research at the site of the bombing also found shards of flesh in the traces of TNT also indicating the fact that there was human being involved in the blast. When the process turned to the collection of samples for the Disaster Victim Identification (DVI), the route veered toward the creation of DNA profiles, which was then compared with the DNA profile of the spatter on the ceiling. What this did was that it would help the investigators in linking the body parts discovered at the site of the bombing and likening them to the body of the suicide bombers. The DNA profile was then run in the DNA database of Scotland Yard enabling them in coming up with an identification of the subject. The second bomb explosion that occurred in Scout Bar 10, took place about 10 minutes after the first. This was also the largest explosion of the afternoon. Initial estimates found that about 18kg of TNT was utlilised in the explosion. There was a creation of a crater, which when analysed revealed the fact that there were traces of chlorate ion that were discovered. Analysis made further also discovered the fact that the bomb itself was created as a mixture of potassium chlorate, sulphur and aluminum, which in turn was made more lethal through the addition of TNT. The mixture thus created was placed inside a plastic box, which had a connection with a detonator chord, made from pentacrythritol tetra nitrate (PETN). This in itself is an organic highly which is explosive. The bomb was placed near the rear exit of the cineman hall and was triggered by a suicide bomber. Samples of DNA material was collected as well for DVI to create DNA profiles. Fragments of biological material found at the bomb epicentre was then analysed further through DNA analysis. The final bomb occurred at Eat Out Restaurant, bar two minutes after the second bombing where approximately 1kg of TNT was used. This was the lightest of the three bombings. Investigations tend to suggest the fact that the bomb was actually initiated with a mobile phone. Samples of fragments were taken back to the laboratory for further testing to create DNA profiles for identification of the victims. The bomb site was then analysed for post-detonation organic explosive compounds. Researchers like Royds et al., (2005) define the term a fast augmentation in the volume and release of energy. This results in the generation of high temperatures which ends up in the release of gases (Royds et al. 2005). The definition also states that there are two basic kinds of constituents that are used in the creation of explosives-the inorganic and the organic elements. The inorganic constituents result in low explosions whereas organic components would manifest in bigger and higher explosives. (Royds et al. 2005) TNT is in fact an en example of organic component while the ammonium nitrate is an an example of inorganic component. The primary explosive that was used in the detonation of the bombs and the explosion therefore was TNT, which is less commonly known as Trinitrotoluene (TNT). The chemical is ordinarily used in military explosives. TNT is a chemical characterized by low a low melting point, it is not highly sensitive to impact, the chemical is stable even during friction and high temperature. It is also characterized by a low sensitivity to distress and electrostatic energy. (Yinon & Zitrin 1996). By itself, TNT is a hazard, given the fact that absorption of TNT can cause medical problems such as a plastic anemia, toxic jaundice, cyanosis, gastritis and dermatitis. (Yinon & Zitrin 1996) one has to however take into consideration, the fact that it is by itself, a secondary explosive It is a secondary explosive, given the fact that it is not sensitive and is restiant to friction, there is a need to detonate the TNT through shock from a primary explosive. (Rendle 2005). There is to be considered also the difficulties that are associated with the use of high explosives. Sometimes the use of high explosives is impracticable, owing to the difficulty of making a proper hole for the cartridge. That, the blow-pipe will do. Among the more important factors involved in the use of high explosives in blasting operations is the means employed to bring about the detonation of the charge, when flame is applied to high explosives many of them may be burned and all them when burning under certain conditions would tend to detonate. This makes it hard to detect these explosives after detonation (Royds et al. 2005) This is attributable to the fact that the small vapor pressure of most commonly found explosives. Because of this, either very large volume of air sample need to be taken or a chemical instrument with small detection levels is used. (Moore 2004) Because vapor phase concentrations of most explosives are so low, sampling and preconcentration are necessary to achieve reasonable ROC (receiver operating characteristic) curves, which allow comparison of detection methods on an equal playing field, on the basis of their sensitivity and selectivity (specificity) (Moore 2004) The sample might also have interference from other components such as an additive or impurity which may lead to false alarms. This is due to the lack of sensitivity of the equipment to differentiate between components which may have derived from solvents or plastics. Fortunately, most of the newly utilized materials have significant vapor pressures, reducing the difficulty of vapor phase detection. On the other hand, traces of explosive materials on the exterior of packaging disappear more quickly for higher vapor pressure materials (Moore, 2005). One of the main chemical instrument used to detect trace elements of explosives in the atmosphere is Gas Chromatography (GC). GC is used for separation of components in a given sample. A carrier gas in the mobile phase pushes the sample through a column and the multiple components in the sample would move in the column at different speeds. (Moore 2004). Chromatographic and spectroscopic instruments are used to identify the chemical make-up of a wide variety of materials from drugs and poisons to the chemicals used in lighting fires. The chromatography process separates materials in to their basic molecular components. The idea for example is that ink could be broken down into its individual dyes, and solvents could be analysed. An instrument that is usually used in the separation of materials is known as the gas chromatograph. The material to be analyses is forced through tubes packed with tiny beads. Large molecules are absorbed through pores in the beads. Large molecules will pass around the beads while the smear molecules are absorbed through pores in the beads. As a result, smaller molecules pass through the tubes more slowly, and all the molecules are separated by size. This technique is extremely accurate and can detect minute amount (one part over million parts) of toxic substances, pesticides or drugs (Friedlander and Phillips, 2001). The gas chromatograph works in tandem with another specialised instrument called mass spectrometer. This device analyses the basic components of a sample material. The idea here is to make use of light in the identification of various molecules in order to produce a ‘readout’ or a visual image of the molecules. This image is known as a spectrogram, and it can be matched with spectrograms made from known chemicals. The spectrometer works because different molecules absorb light at different wavelengths. Each molecule would present a unique identifiable spectrogram. The idea here on the other hand would be to use the other known form of spectroscopy, such as fluorescence spectroscopy and atomic adsorption spectroscopy, both of which were analysed together. One of the better known examples of this type of detection usage is the thermal energy analyzer (TEA) detector. This is a detector for GC and HPLC analysus of nitrogen containing molecules, and has gained immense popularity in the past 10 years. It is in essence a chemiluminescence detector, dealing specifically with components that are made of nitrogen. (Moore 2004). The idea of the function is that is works in accordance with the difference of the capability of the mobile gas phase to conduct heat at the same time it infuses with the analytes. The machine itself is easy to manager and simple to use (Houck & Siegel 2006). The most common known detector that could be used in this case as well is the Mass Spectrometer Detector. The function of the mass spectrum detector emanates from the fact that it is able to detect and identify each analyte component as it comes off the column. A mass spectrum of each substance can be generated very quickly (Houck & Siegal 2006) a mass spectrum of each substance can be generated quickly. The process of identification is efficient especially in case the GC-MS system contains a spectral library. This is a collection of up to thousands of mass spectra known compounds. A reasonably powerful personal computer can take the mass spectrum of an unknown substance and use it to search the spectral library. It then separates the ions through the mass to charge ratio. Through ion impact, electron impact and other methods, it can be ionised when inserted into a high vacuum chamber. It is then separated in the spectrometer according to the geometric path or time of flight (TOF). (Moore 2004) The greater is the number, the bigger is the possibility of the fact that the known and unknown substances are similar if not the same components (Houck & Siegel 2006) GC-MS is fast, selective and reliable however it is only limited to volatile materials (Royds et al. 2005). Tandem Mass Spectrometry (MS/MS) is the process of selecting an ion, causing it fragment and obtaining a mass spectrum of the resulting fragment ions. Fragment ions carry information about the ion structure. A simple single stage tandem mass spectrometry experiment is also often known as the MS/MS experiment. Secondary and higher order stages of fragmentation can also be carried out in which the fragment ion is further fragmented in to the granddaughter ion. The idea essentially is aimed at the improvement of selectivity and sensitivity of MS. When explosive compounds are extracted and separated, it is done through a solid phase extraction and then either through gas or liquid chromatography. (Moore 2004). One of the primary advantages that the GC would tend to have over other instruments such as the high performance liquid chromatography (HPLC) and the capillary electrophoresis (CE) arises from the fact that the instrument could be used in other forms of detection as well. This means, in essence that the sensor could deal with multiple explosive components at one go. GC is also endowed with a higher sensitivity as compared with other instruments with the capability to detect and quantify materials at nanogram units (Perr et al. 2005). The problems that could however associate with the GC is that most organic constituents associated with the GC tend to degrade by the slighted rise in the energy of the GC. Moreover, there is often also the problem, associated with the fact that the ion intensities of the fragments is affected by the acid strength of the reagent gas during chemical ionisation but the mass to charge ratio would not be affected. (Perr et al. 2005) Capillary Electrophoresis is the electrically driven separation method using capillary tubes. Once the sample is placed inside the capillary, an electrical field is tendered in the place of the capillary, so the electrophoresis process could be kick started. Once the length of the capillary has been determined, the primary temperature is altered towards the creation of disparity of separation in the trial by varying the pH. (Lauer et al. 1993) Capillary Electrophoresis could also be utilized in the testing of organic and inorganic constituents, along with the larger bio-molecules inside the restrictions of the same capillary-the only problem would be that the composition of the running buffer needs to altered. (Cruces-Blanco et al. 2007) The main obstacle associated with the process of Capillary Electrophoresis is the high back pressure resulting rim the high viscosity of the mobile phase. The internal damager of the tube tends to be 200-500 µm for gas chromatography, but less than 5 µm for column liquid chromatography. Such a restriction tends to limit the development of capillary liquid chromatography, owing to the difficulty of miniaturizing the injector, connector and detector for high-pressure operation. One could pair detectors such as the UV-VIS with the [process. The idea remains however that these detectors needs to function within the short internal diameter of the capillary. This tends to place a limit on the sensitivity in determining the concentration. The CE could also be coupled with laser-induced fluorescence (LIF) allowing for the excitation of high energy, leading to the high instance of the radiation output. LIF has higher sensitivity but it is more difficult to use and is more expensive. (Cruces-Blanco et al. 2007) Introduction High performance liquid chromatography is a technique that has arisen from the application to liquid chromatography (lc) of theories and instrumentation that were originally developed for gas chromatography (gc) (Moore 2004). The idea is that samples based on water based evideces that have been diluted are pre-concentrated into acetonitrile through a salting out technique (Moore 2004). The stationary phase of a GC is usually polar than the mobile phase. The advantage that an HPLC holds over others arises on the back of the fact that the process could be modified in order to make the mobile phase more polar than the stationary phase, known also as the reverse phase (Houck & Siegel 2006). The problem here is that the process if limited to the organic explosive materials. (Royds et al. 2005) One of the most commonly used detector for a HPLC is the ultraviolet (UV) absorbance detector. The UV/Vis absorbance detector moniors the absorbtion of UV or visble light in the HPLC cluent. They areb the most common detectors sijce most analytes of interest have UV absorbance (Gaurav et al. 2007). These could be made use of for the analysis of substances such as TNT, nitroaromatic, nitramine explosives and more. In order to come up with analysis of substances such as triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) the reverse phase HPLC method with a UV irradiation post column and fluorescence detector can be used. (Gaurav et al. 2007) Another instrument that can be applied to a bomb site is an Infrared Spectrometer. This is the instrument that could be used in the determination of absorption spectrum. Two types of infrared spectrometers are the dispersive and the Fourier transform (FT). the instrument itself is made up of a light source, a prism that works towards the dispersal of the incident light, a monochromatic that works towards the selection and variation of of the wave number of light that is shone on the sample itself. There is also the detector that spies on the amount of light that going through the material being tested and there is a data recorder attached recording to the amount of light transmitted through each wave number through a graph (Tilstone et al. 2006). Separation occurs according to their mobility when they move in the drift gas and the mobility of the sample ions is determine by the mass to charge ratio. (Moore 2004) It functions in atmospheric pressure and ions are detected through the measurement of ion current from a Faraday plate. (Seinfeld & Wormhoudt (1998) The field of forensic Analytical Chemistry is one that is growing on a daily basis backed by instruments that are undergoing processes of constant modification and combination for meeting with the requirements of forensics (Bell 2009). The research itself is driven by the growing concerns of terrorism and terror related activities. Scientists are constantly being urged to come up with innovations and on the more sensitive and versatile chemical instruments thereby aiding the investigations that are related to bombing. Physical and chemical properties of explosives such as vapour pressures, diffusity and diffusion coefficients, and decomposition of explosives such as TNT, RDX and PETN will be investigated upon so information would be needed on them (Steinfield & Wormhoudt 1998). 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