title: Low-pressure barrier discharge ion source using air as a carrier gas and its application to the analysis of drugs and explosives.
abstract: In this work, a low-pressure air dielectric-barrier discharge (DBD) ion source using a capillary with the inner diameter of 0.115 and 12 mm long applicable to miniaturized mass spectrometers was developed. The analytes, trinitrotoluene (TNT), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), 1,3,5,7-tetranitroperhydro-1,3,5,7-tetrazocine (HMX), pentaerythritol tetranitrate (PETN), nitroglycerine (NG), hexamethylene triperoxide diamine (HMTD), caffeine, cocaine and morphine, introduced through the capillary, were ionized by a low-pressure air DBD. The ion source pressures were changed by using various sizes of the ion sampling orifice. The signal intensities of those analytes showed marked pressure dependence. TNT was detected with higher sensitivity at lower pressure but vice versa for other analytes. For all analytes, a marked signal enhancement was observed when a grounded cylindrical mesh electrode was installed in the DBD ion source. Among nine analytes, RDX, HMX, NG and PETN could be detected as cluster ions [analyte + NO3 ](-) even at low pressure and high temperature up to 180 °C. The detection indicates that these cluster ions are stable enough to survive under present experimental conditions. The unexpectedly high stabilities of these cluster ions were verified by density functional theory calculation.
authors.affiliation: Clean Energy Research Center, University of Yamanashi, Takeda-4, Kofu, Yamanashi, 400-8511, Japan.|Institute of Ion-Plasma and Laser Technologies, Durmon Yoli Street 33, Akademgorodok, Tashkent, 100125, Uzbekistan.
authors.forename: Dilshadbek T
authors.initials: DT
authors.lastname: Usmanov
authors.affiliation: Clean Energy Research Center, University of Yamanashi, Takeda-4, Kofu, Yamanashi, 400-8511, Japan.|School of Chemical and Life Sciences, Shenyang Normal University, 253 Huanghe Street, Shenyang, Liaoning, 110034, China.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Takeda-4, Kofu, Yamanashi, 400-8511, Japan.
authors.forename: Lee Chuin
authors.initials: LC
authors.lastname: Chen
authors.affiliation: Clean Energy Research Center, University of Yamanashi, Takeda-4, Kofu, Yamanashi, 400-8511, Japan.
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hiraoka
authors.affiliation: Department of Material Science, Nara Institute of Science and Technology, Takayama-cho, 8916-5, Ikoma, Nara, 630-0101, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yamabe
mesh_terms: D001274:Atmospheric Pressure; D053834:Explosive Agents / Q000032:analysis*; D005740:Gases / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D008958:Models, Molecular; D004364:Pharmaceutical Preparations / Q000032:analysis*
chemical_list: D053834:Explosive Agents; D005740:Gases; D004364:Pharmaceutical Preparations
keywords: NO3−; atmospheric pressure chemical ionization; density functional theory calculations; dielectric-barrier discharge; explosive; on-site mass spectrometry