Use of Mass Spectrometric Vapor Analysis To Improve Canine Explosive Detection Efficiency

Abstract

Canines remain the gold standard for explosives detection in many situations, and there is an ongoing desire for them to perform at the highest level. This goal requires canine training to be approached similarly to scientific sensor design. Developing a canine training regimen is made challenging by a lack of understanding of the canine's odor environment, which is dynamic and typically contains multiple odorants. Existing methodology assumes that the handler's intention is an adequate surrogate for actual knowledge of the odors cuing the canine, but canines are easily exposed to unintentional explosive odors through training material cross-contamination. A sensitive, real-time (∼1 s) vapor analysis mass spectrometer was developed to provide tools, techniques, and knowledge to better understand, train, and utilize canines. The instrument has a detection library of nine explosives and explosive-related materials consisting of 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 2,4,6-trinitrotoluene (TNT), nitroglycerin (NG), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN), triacetone triperoxide (TATP), hexamethylene triperoxide diamine (HMTD), and cyclohexanone, with detection limits in the parts-per-trillion to parts-per-quadrillion range by volume. The instrument can illustrate aspects of vapor plume dynamics, such as detecting plume filaments at a distance. The instrument was deployed to support canine training in the field, detecting cross-contamination among training materials, and developing an evaluation method based on the odor environment. Support for training material production and handling was provided by studying the dynamic headspace of a nonexplosive HMTD training aid that is in development. These results supported existing canine training and identified certain areas that may be improved.

Recent Developments in Spectroscopic Techniques for the Detection of Explosives

“…Due to the importance of rapid, automatic, and non-contact detection of explosives for homeland security and environmental safety [8], a variety of spectroscopic technologies have been employed to detect trace quantities of explosives; for example, terahertz (THz) spectroscopy [9,10], laser induced breakdown spectroscopy (LIBS) [11,12,13,14,15,16], Raman spectroscopy [17,18,19,20,21,22], ion mobility spectrometry (IMS) [23,24,25,26], nuclear magnetic resonance (NMR) [27,28,29,30], nuclear quadrupole resonance (NQR) [31,32,33], laser-induced thermal emissions (LITE) [34,35], infrared (IR) spectroscopy [36,37,38], mass spectrometry [39,40,41,42,43,44,45,46], optical emission spectroscopy (OES) [47,48], photo-thermal infrared imaging spectroscopy (PT-IRIS) [49,50,51], photoacoustic techniques [52,53,54], FT-FIR spectroscopy [55], microwave [56], and millimeter-wave [57], etc. Various electromagnetic radiations such as X-ray [58] and γ rays [59] have also been employed in explosive detection.…”

Nanoporous Silica-Dye Microspheres for Enhanced Colorimetric Detection of Cyclohexanone

“…In the past decade, a large number of analytical methods for trace explosive screening have been investigated, including gas chromatography-mass spectrometry (GC-MS) [7][8][9][10], electronic noses [11][12][13][14], ion mobility spectrometry [5,[15][16][17][18], surface acoustic wave devices [19][20][21] and fluorimetry [22][23][24][25]. Some effective approaches, such as solid-phase microextraction (SPME) [26][27][28], have been extensively explored for ultrasensitive gaseous detection of non-volatile explosives at the ppb or ppt level.…”

Nanoporous Silica-Dye Microspheres for Enhanced Colorimetric Detection of Cyclohexanone

“…In the past decade, a large number of analytical methods for trace explosive screening have been investigated, including GC-MS [7][8][9][10], electronic noses [11][12][13][14], ion mobility spectrometry [5,[15][16][17][18], surface acoustic wave devices [19][20][21] and fluorimetry [22][23][24][25]. Some effective approaches, such as solid-phase microextraction (SPME) [26][27][28], have been extensively explored for ultrasensitive gaseous detection of non-volatile explosives at ppb or ppt level.…”