Direct detection of explosives on solid surfaces by mass spectrometry with an ambient ion source based on dielectric barrier discharge

TLDR

The study introduces a dielectric barrier discharge ionization (DBDI) technique for detecting trace explosives on solid surfaces by ambient mass spectrometry. DBDI employs a needle–plate plasma discharge that generates energetic electrons to desorb and ionize explosives directly from surfaces, producing characteristic negative ions that are transferred to the mass spectrometer for analysis. The method achieves detection limits of 10 pg for TNT, 0.1 ng for RDX, and 1 ng for PETN, works on diverse matrices such as paper, cloth, and soil, yields a 5.57 % RSD for 100 pg TNT, and accurately analyzes mixtures, demonstrating simple, rapid, highly sensitive, and specific detection of trace explosives. © 2007 John Wiley & Sons, Ltd.

Abstract

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. Copyright © 2007 John Wiley & Sons, Ltd.