Detection of Explosives and Related Compounds by Low-Temperature Plasma Ambient Ionization Mass Spectrometry
- 21 December 2010
- journal article
- research article
- Published by American Chemical Society (ACS) in Analytical Chemistry
- Vol. 83 (3), 1084-1092
- https://doi.org/10.1021/ac1029117
Abstract
Detection of explosives is important for public safety. A recently developed low-temperature plasma (LTP) probe for desorption and ionization of samples in the ambient environment ( Anal. Chem. 2008, 80, 9097) is applied in a comprehensive evaluation of analytical performance for rapid detection of 13 explosives and explosives-related compounds. The selected chemicals [pentaerythritol tetranitrate (PETN), trinitrotoluene (TNT), cyclo-1,3,5-trimethylenetrinitramine (RDX), tetryl, cyclo-1,3,5,7-tetramethylenetetranitrate (HMX), hexamethylene triperoxide diamine (HMTD), 2,4-dinitrotoluene, 1,3-dinitrobenzene, 1,3,5-trinitrobenzene, 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,6-dinitrotoluene, and 4-nitrotoluene) were tested at levels in the range 1 pg−10 ng. Most showed remarkable sensitivity in the negative-ion mode, yielding limits of detection in the low picogram range, particularly when analyzed from a glass substrate heated to 120 °C. Ions typically formed from these molecules (M) by LTP include [M + NO2]−, [M]−, and [M − NO2]−. The LTP-mass spectrometry methodology displayed a linear signal response over three orders of magnitude of analyte amount for the studied explosives. In addition, the effects of synthetic matrices and different types of surfaces were evaluated. The data obtained demonstrate that LTP-MS allows detection of ultratrace amounts of explosives and confirmation of their identity. Tandem mass spectrometry (MS/MS) was used to confirm the presence of selected explosives at low levels; for example, TNT was confirmed at absolute levels as low as 0.6 pg. Linearity and intra- and interday precision were also evaluated, yielding results that demonstrate the potential usefulness and ruggedness of LTP-MS for the detection of explosives of different classes. The use of ion/molecule reactions to form adducts with particular explosives such as RDX and HMX was shown to enhance the selectivity and specificity. This was accomplished by merging the discharge gas with an appropriate reagent headspace vapor (e.g., from a 0.2% trifluoracetic acid solution).Keywords
This publication has 46 references indexed in Scilit:
- Reactivity of acetonyl anion with nitroaromatics: an atmospheric pressure chemical ionization studyRapid Communications in Mass Spectrometry, 2005
- Versatile New Ion Source for the Analysis of Materials in Open Air under Ambient ConditionsAnalytical Chemistry, 2005
- A rapid and efficient mass spectrometric method for the analysis of explosivesRapid Communications in Mass Spectrometry, 2002
- Short pulse laser mass spectrometry of nitrotoluenes: ionization and fragmentation behaviorRapid Communications in Mass Spectrometry, 2002
- Determination of nitroaromatic, nitramine, and nitrate ester explosives in soil by gas chromatography and an electron capture detectorTalanta, 2001
- On the Fragmentation of Nitrobenzene and Nitrotoluenes Induced by a Femtosecond Laser at 375 nmThe Journal of Physical Chemistry A, 1997
- A comparison of femtosecond and nanosecond multiphoton ionization and dissociation for some nitro‐moleculesRapid Communications in Mass Spectrometry, 1995
- Multiphoton ionization and dissociation of nitrotoluene isomers by UV laser lightRapid Communications in Mass Spectrometry, 1994
- Reactions in the mass spectrometry of 2,4,6-N-tetranitro-N-methylaniline (tetryl)Rapid Communications in Mass Spectrometry, 1993
- Selective laser-induced resonant two-photon ionization and fragmentation of substituted nitrobenzenes at atmospheric pressureAnalytical Chemistry, 1990