Explosives forensic analysis

The main drawback of the use of color reactions for the analysis of explosives lies in their often low specificity. Although their specificity varies according to the type of reactions - and some reactions are quite specific - it is generally not safe enough to establish an identification of an explosive in a forensic laboratory on color reactions alone. When the color is obtained, the key question is whether other compounds, which are not explosives, can produce the same color under identical experimental conditions. Unfortunately, the answer is usually, yes. Thus, in forensic analysis, where an erroneous identification may lead to a gross injustice, it is generally accepted that the identification of an explosive should not depend on color reactions alone. 

Reliable identification of explosives in a modem forensic laboratory is based on instmmental techniques, mainly spectrometric, often in conjunction with chromatographic methods. Gas chromatography—mass spectrometry (GC/MS) is considered to be an excellent and reliable method in forensic analysis, including the analysis of explosives. 

Mass spectrometry has become a routine technique for forensic analysis of explosives and one of the technologies used for vapor and trace detection of hidden explosives. 

Characterization and origin identification of explosives is important in forensic analysis of post-explosion residues. In addition to the type of explosive used in a... 

A. Crowson, R.W. Hdey and C.C. Todd, Quality assurance testing of an explosive trace analysis laboratory , J. Forensic Sci., 46 (2001) 53—56. 

WFLETC). From February 2002 to the present time, he has helped develop explosive analysis programs and train personnel for the Georgia Bureau of Investigation, Tucson Police Department, and the Texas Department of Public Safety. He also has provided forensic analysis in various areas for both private companies and corporations, and law enforcement agencies. 

In forensic science, FTIR microscopy has been used to examine paint chips from automobile accidents. An example of a paint chip spectmm is shown in Fig. 4.29. Hit-and-run drivers frequently leave traces of paint on cars with which they collide. Identification of the paint can help to identify the car. Other uses of an IR microscope in forensic analysis include the examination of hbers, dmgs, and traces of explosives. 

Some applications for which NMR has been used in forensic analysis include the identification of compounds by comparison of spectra with those of authentic materials, the determination of structures of unknown compounds such as designer drugs, the identification of impurities in illicit drugs, the determination of optical purity of drugs, and the characterization of explosives, accelerants, fire residues, and various body fluids or tissue extracts. This article will briefly review each of these applications. 

Other uses of an IR microscope in forensic analysis include the examination of fibers, drugs, and traces of explosives. For example, oxidation of hair can occur chemically or by sunlight oxidation of cystine to cysteic acid can be seen in hair fibers by FTIR microscopy (Robotham and Izzia). Excellent examples in full color of FTIR imaging microscopy can be found on the websites of companies like PerkinElmer and Thermo Fisher Scientific. Our limitations in use of gray scale make many of the examples unsuited for reproduction in the text. A novel IR microscope combined with atomic force microscopy, the nanoIR platform from Anasys Instruments (www.anasysinstruments.com), permits nanoscale IR spectroscopy, AFM topography, nanoscale thermal analysis, and mechanical testing. 

Although relevant exercises have been conducted, and Cold War nuclear weapons programs provide validated analytic platforms, there have been no actual post-det terrorist incidents involving an IND or RDD to date. Consequently, no technical investigations in the contemporary embodiment of nuclear forensic analysis exist for an actual post-det situation, and all discussed case studies necessarily focus on interdicted, pre-det materials. (However, a nuclear accident that is perhaps exemplary of maximum-credible consequences of successful terrorist activities was the uncontrolled criticality and resultant explosion of the Soviet RBMK power reactor at Chernobyl in 1986.)... 

Benson, S.I, Lennard, C.J., Maynard, R, Hfll, D.M., Andrew, A.S., Roux, C. (2009) Forensic analysis of explosives using isotope ratio mass spectrometry (IRMS)— discrimination of ammonium nitrate sources. Sci. Justice, 49(2), 73-80. 

The importance of detection and forensic analysis of TATP is abundantly clear from the nature and number of incidents involving the material. Details of the synthesis and chemical characteristics of TATP will be presented prior to a discussion of methodologies for the analysis of this improvised explosive. 

One of the first reports of a forensic analysis of TATP in the United States came following an accidental detonation of a homemade TATP explosives device [41]. The TATP was analyzed by direct insertion probe-mass spectrometry (DIP-MS) with El, as well as methane and... 

McCord, B., et al. "Forensic Analysis of Explosives Using Ion Chromatographic Methods." Arudytica Chimi-Oi Acte 288 (1994), 43-56. 

Microscopists in every technical field use the microscope to characterize, compare, and identify a wide variety of substances, eg, protozoa, bacteria, vimses, and plant and animal tissue, as well as minerals, building materials, ceramics, metals, abrasives, pigments, foods, dmgs, explosives, fibers, hairs, and even single atoms. In addition, microscopists help to solve production and process problems, control quaUty, and handle trouble-shooting problems and customer complaints. Microscopists also do basic research in instmmentation, new techniques, specimen preparation, and appHcations of microscopy. The areas of appHcation include forensic trace evidence, contamination analysis, art conservation and authentication, and asbestos control, among others. 

Elemental Analysis, 2) Determination of Pellet Weight in Primers, 3) Determination of Gunpowder Residues in Forensic.Investigations, 4) Detection of Explosives in Buried Mines, 5) Detection of Hidden Explosives in Baggage, and 6) Explosives Safety in Neutron Activation Analysis... 

Trace analysis of explosives is of major importance in forensic and environmental applications [6]. In forensics, the applications include analysis of postexplosion residues and identification of traces of explosives on suspects hands, clothing and other related items. The results of these analyses are not only necessary for the investigation of a bombing but can also serve as evidence in court. 

The methodologies for the analysis of explosives for both forensic and environmental applications are very similar, using mainly GC/MS and LC/MS. As explosives are thermally labile compounds, LC/MS has an obvious advantage over GC/MS, as the chromatography is carried out at room temperature. 

Mass spectrometry, and especially LC/MS, is a major technique in the analysis of explosives. It combines good sensitivity and selectivity, and in addition to MS/ MS, provides an excellent identification tool for the forensic analyst. 

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