A microsensor for trinitrotoluene vapour

Pinnaduwage, Lal A.; Gehl, Anthony C.; Hedden, D. L.; Muralidharan, Govindarajan; Thundat, Thomas; Lareau, Richard T.; Sulchek, Todd; Manning, M. Lisa; Rogers, Bill; Jones, Matthew R.; Adams, Jonathan D.

doi:10.1038/425474a

Cited by 177 publications

(91 citation statements)

References 8 publications

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“…It also demonstrates potential applications of these reactions in distinguishing dinitrobenzene isomers and in selective detection of TNT in mixtures, a current challenging issue in analytical chemistry [25][26][27][28]. In addition, the gas-phase aldol-like condensation reaction of [TNT-NO] Ϫ (m/z 197), a major TNT fragment ion, with benzaldehyde PhCHO followed by intramolecular cyclization to give rise to the derivatized benzofuran ion m/z 257 is reported.…”

Section: Eisenheimer Complexes First Proposed Bymentioning

confidence: 87%

Meisenheimer complexes bonded at carbon and at oxygen

Chen

Cooks

2004

J. Am. Soc. Mass Spectrom.

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The carbon-bonded gas-phase Meisenheimer complex of 2,4,6-trinitrotoluene (TNT) and the nitromethyl carbanion CH 2 NO 2 Ϫ (m/z 60) is generated for the first time by chemical ionization using nitromethane as the reagent gas. Collision-induced dissociation (CID) of the Meisenheimer complex furnishes deprotonated TNT, a result of the higher gas-phase acidity of TNT than nitromethane. The formation of Meisenheimer complexes with CH 2 NO 2 Ϫ in the gas phase is selective to highly electron-deficient compounds such as dinitrobenzene and trinitrobenzene and does not occur with organic molecules with lower electron-affinity such as methanol, methylamine, propionaldehyde, acetone, ethyl acetate, chloroform, toluene, m-methoxytoluene, and even nitrobenzene and p-fluoronitrobenzene. As such, the reaction allows selective detection of TNT in mixtures. Meisenheimer complexes between CH 2 NO 2 Ϫ and the three dinitrobenzene isomers display distinctive fragmentations. The oxygen-bonded -complex of TNT with the deprotonated hemiacetal anion CH 3 OCH 2 O Ϫ (m/z 61), represents a different type of Meisenheimer complex. It displays characteristic fragmentation involving loss of HNO 2 upon CID. The combination of a selective ion/molecule reaction (Meisenheimer complex formation) followed by a characteristic CID process provides a second novel and highly selective approach to the detection of TNT and closely related compounds in mixtures. The assay is readily implemented using neutral loss scans in a triple quadrupole mass spectrometer. Gas-phase reactions of denitrosylated TNT with benzaldehyde produce the corresponding dihydrofuran in an aldol condensation, a result that parallels the corresponding condensed-phase reaction. (J Am Soc Mass Spectrom 2004, 15, 998 -1004

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Section: Eisenheimer Complexes First Proposed Bymentioning

confidence: 87%

Meisenheimer complexes bonded at carbon and at oxygen

Chen

Cooks

2004

J. Am. Soc. Mass Spectrom.

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“…This indicates that most current works [6,8,146] are restricted to sensing specific chemicals such as trinitrotoluene vapor [147] and/or toxic chemicals [148] among the mixture of various chemicals in air. To our best knowledge, the multiplexed specific chemical detection among various chemical species in an ambient environment has not been realized using nanomechanical resonators.…”

Section: Resonator-based Chemical Detectionmentioning

confidence: 99%

Nanomechanical resonators and their applications in biological/chemical detection: Nanomechanics principles

et al. 2011

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Recent advances in nanotechnology have led to the development of nano-electro-mechanical systems (NEMS) such as nanomechanical resonators, which have recently received significant attention from the scientific community. This has not only been for their capability for the label-free detection of bio/chemical-molecules at single-molecule (or atomic) resolution for future applications such as the early diagnostics of diseases such as cancer, but also for their unprecedented ability to detect physical quantities such as molecular weight, elastic stiffness, surface stress, and surface elastic stiffness for adsorbed molecules on the surface. Most experimental works on resonator-based molecular detection have been based on the principle that molecular adsorption onto a resonator surface increases the effective mass, and consequently decreases the resonant frequencies of the nanomechanical resonator. However, this principle is insufficient to provide fundamental insights into resonator-based molecular detection at the nanoscale; this is due to recently proposed novel nanoscale detection principles including various effects such as surface effects, nonlinear oscillations, coupled resonance, and stiffness effects. Furthermore, these effects have only recently been incorporated into existing physical models for resonators, and therefore the universal physical principles governing nanoresonator-based detection have not been completely described. Therefore, our objective in this review is to overview the current attempts to understand the underlying mechanisms in nanoresonator-based detection using physical models coupled to computational simulations and/or experiments. Specifically, we will focus on issues of special relevance to the dynamic behavior of nanoresonators and their applications in biological/chemical detection: the resonance behavior of micro/nano-resonators; resonator-based chemical/biological detection; physical models of various nanoresonators such as nanowires, carbon nanotubes, and graphene. We pay particular attention to experimental and computational approaches that have been useful in elucidating the mechanisms underlying the dynamic behavior of resonators across multiple and disparate spatial/length scales, and the resulting insight into resonator-based detection that has been obtained. We additionally provide extensive discussion regarding potentially fruitful future research directions coupling experiments and simulations in order to develop a fundamental understanding of the basic physical principles that govern NEMS and NEMS-based sensing and detection applications.

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“…As with TPD, our method can take advantage of a programmable heating rate to increase the device sensitivity to specific thermal characteristics of interest. Experiments with thermally induced deflagration of adsorbed explosives on microcantilevers 16,17 were able to differentiate energetic materials from nonenergetic materials, however, they were not able to differentiate between the individual explosives. In addition to identifying energetic material, the micro-differential thermal analysis ͑DTA͒ approach presented here allows the identification of different explosives.…”

Section: Review Of Scientific Instrumentsmentioning

confidence: 99%

Micro-differential thermal analysis detection of adsorbed explosive molecules using microfabricated bridges

Senesac

Greve

et al. 2009

Review of Scientific Instruments

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Although micromechanical sensors enable chemical vapor sensing with unprecedented sensitivity using variations in mass and stress, obtaining chemical selectivity using the micromechanical response still remains as a crucial challenge. Chemoselectivity in vapor detection using immobilized selective layers that rely on weak chemical interactions provides only partial selectivity. Here we show that the very low thermal mass of micromechanical sensors can be used to produce unique responses that can be used for achieving chemical selectivity without losing sensitivity or reversibility. We demonstrate that this method is capable of differentiating explosive vapors from nonexplosives and is additionally capable of differentiating individual explosive vapors such as trinitrotoluene, pentaerythritol tetranitrate, and cyclotrimethylenetrinitromine. This method, based on a microfabricated bridge with a programmable heating rate, produces unique and reproducible thermal response patterns within 50 ms that are characteristic to classes of adsorbed explosive molecules. We demonstrate that this micro-differential thermal analysis technique can selectively detect explosives, providing a method for fast direct detection with a limit of detection of 600×10−12 g.

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A microsensor for trinitrotoluene vapour

Cited by 177 publications

References 8 publications

Meisenheimer complexes bonded at carbon and at oxygen

Meisenheimer complexes bonded at carbon and at oxygen

Nanomechanical resonators and their applications in biological/chemical detection: Nanomechanics principles

Micro-differential thermal analysis detection of adsorbed explosive molecules using microfabricated bridges

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