title: Atmospheric pressure chemical ionization of explosives using alternating current corona discharge ion source.
abstract: The high-sensitive detection of explosives is of great importance for social security and safety. In this work, the ion source for atmospheric pressure chemical ionization/mass spectrometry using alternating current corona discharge was newly designed for the analysis of explosives. An electromolded fine capillary with 115 µm inner diameter and 12 mm long was used for the inlet of the mass spectrometer. The flow rate of air through this capillary was 41 ml/min. Stable corona discharge could be maintained with the position of the discharge needle tip as close as 1 mm to the inlet capillary without causing the arc discharge. Explosives dissolved in 0.5 µl methanol were injected to the ion source. The limits of detection for five explosives with 50 pg or lower were achieved. In the ion/molecule reactions of trinitrotoluene (TNT), the discharge products of NOx (-) (x = 2,3), O3 and HNO3 originating from plasma-excited air were suggested to contribute to the formation of [TNT - H](-) (m/z 226), [TNT - NO](-) (m/z 197) and [TNT - NO + HNO3 ](-) (m/z 260), respectively. Formation processes of these ions were traced by density functional theory calculations. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: Clean Energy Research Center, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi, 400-8511, Japan.|Institute of Ion-Plasma and Laser Technologies, Dormon Yoli Street 33, Akademgorodok, Tashkent, 100125, Uzbekistan.
authors.forename: D T
authors.initials: DT
authors.lastname: Usmanov
authors.affiliation: Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi, 400-8511, Japan.
authors.forename: L C
authors.initials: LC
authors.lastname: Chen
authors.affiliation: Clean Energy Research Center, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi, 400-8511, Japan.|School of Chemical and Life Sciences, Shenyang Normal University, Shenyang, 110034, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Fukui Institute of Fundamental Chemistry, Kyoto University, Takano, Sakyoku, Kyoto, 606-8103, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Yamabe
authors.affiliation: Fukui Institute of Fundamental Chemistry, Kyoto University, Takano, Sakyoku, Kyoto, 606-8103, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Sakaki
authors.affiliation: Clean Energy Research Center, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi, 400-8511, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hiraoka
keywords: atmospheric pressure chemical ionization; corona discharge; explosives; on-site mass spectrometry; transition state