Explosives trace detection

W.J. McGann, P. Haigh andJ.L. Neves, Expanding the capability of IMS explosive trace detection. International Journal for Ion Mobility Spectrometry 5(3) (2002) 119-122. 

TSA Criteria for Certification of Explosives Trace Detection Systems, 67 Fed. Reg. 48506-48509 (24 July 2002). 

Explosive-related chemical Explosive remnants of war Electrostatic discharge Explosives trace detection Explosive vapor detection (U.S.) Federal Aviation Administration Field asymmetric ion mobility spectrometry Fertilizer-Grade AN (ammonium nitrate)... 

A commercial explosive trace detection system, Hitachi DS-120E, based on a quadrupole mass spectrometer was built [7], Ionization is carried out by corona discharge and APCI. Sampling is carried out by wiping surfaces on suspicious objects for traces of explosives. The wipe sheet is inserted into the detection system, where it is heated in order to desorb the trace explosives into the ion source. Analysis time is 5-10 s. 

Thermo Scientific Corporation, EGISIM Defender, Portable Lightweight Desktop Explosives Trace Detection System, Waltham, MA, USA (2007), available at http //www.thermo.com/ eThermo/CMA/PDFs/Product/productPDF 30772.pdf. 

EGIS Defender Explosives Trace Detection System... 

Takada, Y. (2007) Explosives trace detection by mass spectrometry. Journal of the Mass Spectrometry Society of Japan, 55, 91-94. 

The International Civil Aviation Organization (ICAO) responded on 30 December 2009 with a communique to its points of contacts in member States to the effect inter alia that ICAO Member States were encouraged to conduct a risk assessment, taking into consideration all the relevant factors, and implement appropriate screening measures. Where additional screening measures are considered necessary, these may include the application of explosives trace detection technology, physical searches and randomly-deployed explosives detection canine teams, among others. 

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. 

A. Kamyshny, S. Magdassi, Y. Avissov andj. Almog, Water-soaked evidence detectability of explosive traces after immersion in water , J. Forensic Sci., 48 No.2 (2003) 312—317. 

The equipment for screening passengers and baggage is designed to identify trace amounts of specific known explosives. Analytic trace detection is conducted using mass spectrometry, gas chromatography, chemical luminescence, or ion mobility spectrometry. Ion mobility spectrometry is most commonly used. Novel explosive material wiU not be probably detected by these systems. Information on the equipment s technical performance is not publicly available because of security reasons, which inhibits an independent analysis of equipment s performance [160]. 

Fisher, M. and C. Cumming. Trace detection of nitroaromatic explosives by fluorescence quenching of novel polymer materials, in Proceedings of the U.S. Federal Aviation Administration s Third International Aviation Security Technology Symposium, Atlantic City, NJ, November 27-30, 2001. 

Sampling is difficult because the vapor pressures for most explosives are very low. For example, the room temperature equilibrium headspace concentration of RDX in air is about 10 pptv (parts per trillion by volume). Collection of vapor is further compounded for explosives that are bound in matrices and wrappers and/or are concealed in wrappings or baggage. The prospects for trace detection of explosives are considered to be better when sampling objects for explosives contamination in the form of particles and residue. 

The lack of a capability to screen for explosives hidden on an individual is a major vulnerability in aviation and general security. Personal privacy issues and perceived health risks have deterred the use of bulk detectors, such as X ray, X-ray backscatter, and millimeter wave, for screening of individuals for concealed explosives. Consequently, the TSA is focused on trace detection as the best solution for passenger screening in airports. The TSA has determined that individuals carrying as little as 1 lb of concealed explosives get sufficiently contaminated to be detectable by portal devices that use trace detectors. The level of contamination on an individual s exterior clothing that can be routinely detected by the best portal devices is about 1 pg or about 1 part in 109 of the explosive mass. 

Selective, highly sensitive sensors that can detect trace amounts of explosive vapors in real time are needed to help combat terrorism [1-4], Trace detection of explosives, however, is a formidable task. Selectivity is difficult to achieve because many chemicals can be used as explosives, and they differ from each other in their chemical properties. The extremely small vapor pressures of the explosives make it challenging to achieve highly sensitive vapor-based detection. Also, because the terrorist threat is very broad, combating it requires widespread deployment of inexpensive, low-power-consuming sensors. Therefore, devices... 

The analysis of explosives has rather obvious forensic implications. HPLC applications have been published concerning both the analysis of postblast residues in the attempt to identify the explosive used, and the detection of explosive traces on the hands and clothing of a suspect in order to provide... 

The chapter has been structured into several sections first, there is a brief introduction, including a description of the concept and general principles of CL and how it is used in the field of explosives. The second section describes CL applications in the field of explosives and focuses in particular on the thermal energy analyser (TEA) because of its important role in the trace detection of explosives. The recent applications of luminol CL and electrochemiluminescence (ECL) to explosive detection are also described. Finally, because much of the research into explosive detectors has been directed towards civilian safety, a third section describes how CL is used as a security measure to detect explosives. 

CL (TEA), luminol CL and ECL detection systems in their applications to the trace detection of explosives and briefly summarizes the reactions and mechanisms involved. 

Traces of explosives are commonly present in very low levels in samples that are analysed, so it is important to take sensitivity into account when designing detectors for explosive detection. As a rough rule of thumb , Nambayah and Quickenden [38] reported that a method suitable for direct explosive vapour detection should be able to detect explosive concentrations at less than 1 ng/L. They made an exhaustive study of the lowest experimental detection limits achieved with various analytical techniques reported in the literature on traces of explosive, and they informed that headspace GC-electron capture detector (ECD) followed by immunosensor techniques achieves the lowest detection limits (from 0.07 to 20 ng/L). 

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