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

Seto, Yasuo, Hashimoto, Ryota, Taniguchi, Takashi, Ohrui, Yasuhiko, Nagoya, Tomoki, Iwamatsu, Tadashi, Komaru, Shohei, Usui, Daisuke, Morimoto, Satoshi, Sakamoto, Yasuhiro, Ishizaki, Atsushi, Nishide, Tatsuhiro, Inoue, Yoko, Sugiyama, Hiroaki, Nakano, Nobuo
Analytical chemistry 2019 v.91 no.8 pp. 5403-5414
aluminum, atmospheric pressure, chlorides, chlorine, cyanates, cyanogen, detection limit, electric potential difference, electrodes, gold, hydrogen cyanide, hydrolysis, ionization, ions, nanogold, nanosilver, oxygen, silicone, silver, spectrometers, spectroscopy, sulfur, superoxide anion
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 (K₀) 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 (K₀ = 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 (K₀ = 2.36; resolution = 1.2; and LOD = 0.6 mg/m³), which was assigned to Cl–. Lewisite 1 was detected as two peaks (K₀ = 1.68 and 1.34; LOD = 12 and 15 mg/m³). The K₀ = 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.