Luminescence-based methods for sensing and detection of explosives
Melissa S. Meaney & Victoria L. McGuffin
Received: 11 December 2007 / Revised: 15 May 2008 / Accepted: 20 May 2008 / Published online: 28 June 2008 # Springer-Verlag 2008
Abstract The detection of explosives and related compounds is importantin both forensic and environmental applications. Luminescence-based methods have been widely used for detecting explosives and their degradation products in complex matrices. Direct detection methods utilize the inherent fluorescence of explosive molecules or the luminescence generated from chemical reactions. Direct detection methods include high-energy excitation techniques such as gamma-ray andx-ray fluorescence, detection of decomposition products by fluorescence or chemiluminescence, and detection following reduction to amines or another reaction to produce fluorescent products from the explosive. Indirect detection methods utilize the interference caused by the presence of explosive compounds with traditional processes of fluorescence and fluorescence quenching. Indirect detectionmethods include quenching of solution-phase, immobilized, and solid-state fluorophores, displacement of fluorophores, fluorescence immunoassay, and reactions that produce fluorescent products other than the explosive. A comprehensive review of these methods is presented. Keywords Luminescence . Fluorescence . Fluorescence quenching . Chemiluminescence . Explosives
Introduction Explosives andexplosive-like compounds are important in many diverse fields. Detection of these materials is
M. S. Meaney : V. L. McGuffin (*) Department of Chemistry, Michigan State University, East Lansing, MI 48824-1322, USA e-mail: firstname.lastname@example.org M. S. Meaney e-mail: email@example.com
necessary in a variety of complex environments, including mine fields, munitions storage facilities, wastewatertreatment facilities, transportation areas, and blast sites. In each of these settings, sensitive and timely detection of explosive materials is necessary to ensure the safety and security of the surrounding area. Of these, the most widely studied are nitrated explosives, including nitroaromatics such as TNT, nitramines such as RDX, and nitrate esters such as PETN (Table 1). Military explosives areoften composite materials consisting of several of these explosives together with fuels and other excipients (Table 2) . Extensive characterization of these explosives has led to extremely low detection limits in the laboratory setting. In the field, however, where untrained personnel must identify explosive compounds in the presence of abundant contamination, a simple and effective system isneeded to detect these materials at trace levels. In many cases, detection of hidden explosive devices is difficult owing to the low vapor pressures of many explosives. Rising interest in defense and homeland security has led to improved technologies for military explosives detection. These improvements have, in turn, led to increased use of non-nitrated explosive materials . Most recently,liquid or peroxide-based explosives such as TATP and HMTD have been involved in cases of terrorism or drug-related crime [2–4]. Although these compounds are easily synthesized from readily available materials and are comparable in power to TNT, their instability and rapid sublimation make them of little use in military applications. Because these materials are new and significantly different fromother classes of explosives, the best methods for their determination have yet to be identified. Fluorescence- and luminescence-based methods for explosives detection offer many benefits over other com-
2558 Table 1 pounds Compound Nitromethane 2,3-Dimethyl-2,3-dinitrobutane Nitrobenzene o-Dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene 1,3,5-Trinitrobenzene 2-Nitrotoluene, 3-nitrotoluene,...