Detection of Nitro-Based and Peroxide-Based Explosives by Fast Polarity-Switchable Ion Mobility Spectrometer with Ion Focusing in Vicinity of Faraday Detector

Abstract

Ion mobility spectrometer (IMS) has been widely deployed for on-site detection of explosives. The common nitro-based explosives are usually detected by negative IMS while the emerging peroxide-based explosives are better detected by positive IMS. In this study, a fast polarity-switchable IMS was constructed to detect these two explosive species in a single measurement. As the large traditional Faraday detector would cause a trailing reactant ion peak (RIP), a Faraday detector with ion focusing in vicinity was developed by reducing the detector radius to 3.3 mm and increasing the voltage difference between aperture grid and its front guard ring to 591 V, which could remove trailing peaks from RIP without loss of signal intensity. This fast polarity-switchable IMS with ion focusing in vicinity of Faraday detector was employed to detect a mixture of 10 ng 2,4,6-trinitrotoluene (TNT) and 50 ng hexamethylene triperoxide diamine (HMTD) by polarity-switching, and the result suggested that [TNT-H]− and [HMTD+H]+ could be detected in a single measurement. Furthermore, the removal of trailing peaks from RIP by the Faraday detector with ion focusing in vicinity also promised the accurate identification of KClO4, KNO3 and S in common inorganic explosives, whose product ion peaks were fairly adjacent to RIP.

Qualitative Detection Toward Military and Improvised Explosive Vapors by a Facile TiO2 Nanosheet-Based Chemiresistive Sensor Array

“…Compared with other vapor electrical sensors (Che et al, 2010;Chen et al, 2010;Wang et al, 2011a;Aluri et al, 2013;Schnorr et al, 2013;Liu et al, 2015;Yang et al, 2015), it shows a higher sensitivity toward TNT, DNT, and PNT, and can detect RDX vapor at ppt level ( Supplementary Table 2). Compared with other military explosive detecting techniques (Andrew and Swager, 2007;He et al, 2009;Olley et al, 2010;Zhu et al, 2011;Wang et al, 2014;Zhou et al, 2015), it can identify 5 military explosives within 30 s and avoid (1) the interference induced by other substances, (2) the large and expensive instrumentation, and (3) complicated operating procedure, which might be problematic for fluorescence, SERS, and IMS ( Supplementary Table 3). In the case of detection of improvised explosives, the present gas sensor array can discriminatively identify 6 improvised explosive vapors within 75 s, which is much more efficient compared with CE and IC ( Supplementary Table 4; Hutchinson et al, 2007;Peng et al, 2014).…”

“…During the past decade, several techniques have been applied for the detection of military explosive vapors, such as fluorescence (Andrew and Swager, 2007;He et al, 2009;Olley et al, 2010;Zhu et al, 2011), surface enhanced Raman scattering (SERS) Wang et al, 2014), ion mobility spectrometer (IMS) (Zhou et al, 2015), and chemiresistive sensors (Che et al, 2010;Chen et al, 2010;Engel et al, 2010;Wang et al, 2011a;Aluri et al, 2013). However, most of the previous reports were unable to realize the identification of different kinds of military explosives (Andrew and Swager, 2007;He et al, 2009;Che et al, 2010;Chen et al, 2010;Engel et al, 2010;Olley et al, 2010;Wang et al, 2011a;Zhu et al, 2011;Aluri et al, 2013;Zhou et al, 2015). Moreover, some of the reported techniques suffer from the extremely low response at room temperature Aluri et al, 2013) and time consuming problem (Hutchinson et al, 2007;Zhu et al, 2011), inhabiting their application in the rapid on-the-spot detection of military explosives.…”

Exploring Rapid, Sensitive and Reliable Detection of Trace Explosives Using Paper Spray Mass Spectrometry (PS‐MS)

“…TD-IMS also requires the sample to be introduced in vapour form. Whilst this is not a problem for explosives such as nitrotoluenes and nitroglycerine de-rivatives, others such as 1,3,5-trinitro-1,3,5-triazinane (RDX), hexamethylene triperoxide diamine (HMTD) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) have been found to have inefficient desorption processes due to their lower vapour pressures and thermal instability [15,16,35,36]. The wide range of vapour pressures and thermal labilities of the explosive materials make developing a universal method using TD difficult; optimising experimental conditions for one material would result in a decrease in sensitivity for another.…”

Miniature Nitro and Peroxide Vapor Sensors Using Nanoporous Thin Films

“…Sniffer dogs cost tens of thousands of dollars to train, a handler is required and they can only be deployed for a limited time before being rested. Alternatively, a range of developed technologies such as ion mobility [4], infra-red spectroscopy [5], fluorescent polymers [6], and colorimetric kits [7] have been utilized. Such systems range from static walk-through machines to portable devices such as the state-of-the-art SABRE ™ 5000 (Smiths Group plc).…”