title: Direct detection of explosives on solid surfaces by mass spectrometry with an ambient ion source based on dielectric barrier discharge.
abstract: Trace amounts of explosives on solid surfaces were detected by mass spectrometry at ambient conditions with a new technique termed dielectric barrier discharge ionization (DBDI). By the needle-plate discharge mode, a plasma discharge with energetic electrons was generated, which could launch the desorption and ionization of the explosives from solid surfaces. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT), and pentaerythritol tetranitrate (PETN) were desorbed directly from the explosives-contaminated surface by DBDI, forming the typical anions of [TNT](-), [TNT - H](-), [RDX + NO(2)](-), [PETN + ONO(2)](-), and [RDX + ONO(2)](-). The ions were transferred into the MS instrument for analysis in the negative ion mode. The detection limit of present method was 10 pg for TNT (m/z 197, S/N 8 : 1), 0.1 ng for RDX (m/z 284, S/N 10 : 1), and 1 ng for PETN (m/z 260, S/N 12 : 1). The present method allowed the detection of trace explosives on various matrices, including paper, cloth, chemical fiber, glass, paints, and soil. A relative standard deviation of 5.57% was achieved by depositing 100 pg of TNT on these matrices. The analysis of A-5, a mixture of RDX and additives, has been carried out and the results were consistent with the reference values. The DBDI-MS method represents a simple and rapid way for the detection of explosives with high sensitivity and specificity, which is especially useful when they are present in trace amounts on ordinary environmental surfaces.
authors.affiliation: Department of Chemistry, Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry, Tsinghua University, 100084 Beijing, P. R. China.
authors.forename: Na
authors.initials: N
authors.lastname: Na
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.forename: Mengxia
authors.initials: M
authors.lastname: Zhao
authors.forename: Sichun
authors.initials: S
authors.lastname: Zhang
authors.forename: Chengdui
authors.initials: C
authors.lastname: Yang
authors.forename: Xiang
authors.initials: X
authors.lastname: Fang
authors.forename: Xinrong
authors.initials: X
authors.lastname: Zhang