Development of Ion Mobility Spectrometry with Novel Atmospheric Electron Emission Ionization for Field Detection of Gaseous and Blister Chemical Warfare Agents

Abstract

Drift tube ion mobility spectrometry with a novel atmospheric electron emission (AEE) source was developed for determination of gaseous and blister chemical warfare agents (CWAs) in negative mode. The AEE source was fabricated from an aluminum substrate electrode covered with 1 μm silver nanoparticle-dispersed silicone resin and a thin gold layer. This structure enabled stable tunneling electron emission upon the application of more than 11 V potential under atmospheric pressure. The reactant ion peak (RIP) was observed for the reduced mobility constant (K 0) of 2.18 and optimized at the charging voltage of 20 V. This RIP was assigned to O2 – by using a mass spectrometer. Hydrogen cyanide was detected as a peak (K 0 = 2.47) that was discriminatively separated from the RIP (resolution = 1.4), with a limit of detection (LOD) of 0.057 mg/m3, and assigned to CN– and OCN–. Phosgene was detected as a peak (K 0 = 2.36; resolution = 1.2; and LOD = 0.6 mg/m3), which was assigned to Cl–. Lewisite 1 was detected as two peaks (K 0 = 1.68 and 1.34; LOD = 12 and 15 mg/m3). The K 0 = 1.68 peak was ascribed to a mixture of adducts of molecules or the product of hydrolysis with oxygen or chloride. Cyanogen chloride, chlorine, and sulfur mustard were also well detected. The detection performance with the AEE source was compared with those under corona discharge and 63Ni ionizations. The advantage of the AEE source is the simple RIP pattern (only O2 –), and the characteristic marker ions contribute to the discriminative CWAs detection.

Fast Sensing of Hydrogen Cyanide (HCN) Vapors Using a Hand-Held Ion Mobility Spectrometer with Nonradioactive Ionization Source

“…Reduced ion mobility for the single ion peak generated in the negative mode was found to be K 0 = 2.38 cm 2 V −1 s −1 , a value that is in good accordance with other results indicated in the literature: 2.38 cm 2 V −1 s −1 [ 19 ], 2.46 cm 2 V −1 s −1 [ 20 ], or 2.47 cm 2 V −1 s −1 [ 18 ]. Figures of merit given in the literature and those found by us are summarized in Table 5 , where LoD is the limit of detection and LoQ the limit of quantification, respectively.…”

“…Nevertheless, we can make the reasonable assumption that, in the negative ion mode, the product ions that are generated by hydrogen cyanide may be considered as cyanide ions, most probably clustered with neutral species such as water, carbon dioxide, or nitrogen. Recent studies have reported the formation of CN − and OCN − ions from vapors of hydrogen cyanide [ 18 ].…”

“…Unlike the aspiration-type IMS systems, where the detection sensitivity towards HCN is poor (a response is elicited only at very high levels of HCN vapors, of several hundreds of ppm v ) [ 21 , 22 , 23 ], the classical (ToF) IMS devices equipped with either nonradioactive [ 18 , 24 , 25 , 26 ] or radioactive [ 19 , 20 , 27 ] ionization sources showed similar analytical performances (as LoD, LoQ, measurement range). The only notable exception is the pretty poor LoD of 10 mg m −3 reported in [ 26 ], which could be explained, very probably, by errors that occurred when generating the standard atmospheres with HCN vapors using chemical reaction between a solution of cyanide and an acid.…”

Rapid Discrimination of Citrus reticulata ‘Chachi’ by Electrospray Ionization–Ion Mobility–High-Resolution Mass Spectrometry

“…The ions can be separated by their charge state, size, shape, charge position, or structural rigidity [32]. For sensitive detection, IMS is suitable for the trace detection of some volatile organic compounds, such as narcotics [33], explosives [34], chemical warfare [35], and air pollutants [36]. Since the first commercial IMS was manufactured in the 1960s, it has undergone rapid growth over the past decades and been used widely in many laboratories.…”

Parallel Coupling of Ion Mobility Spectrometry and Ion Trap Mass Spectrometry for the Real-Time Alarm Triggering and Identification of Hazardous Chemical Leakages

“…Stand-alone ion mobility spectrometry (IMS) and portable mass spectrometry (MS) are two techniques employed for field-screening hazardous chemicals, such as explosives, − illegal drugs, , and chemical warfare agents (CWAs). − The merits of an IMS system, including the high sensitivity, fast response (millisecond level), portability, and low cost, make it suitable for on-site monitoring of hazardous chemicals with millisecond temporal resolutions . IMS is suitable for triggering an alarm but not for identification due to its insufficient resolution .…”