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Scientific Articles - PTR-MS Bibliography

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[Sulzer2012] Sulzer, P., F. Petersson, B. Agarwal, K. H. Becker, S. Juerschik, T. D. Maerk, D. Perry, P. Watts, and C. A. Mayhew, "Proton transfer reaction mass spectrometry and the unambiguous real-time detection of 2,4,6 trinitrotoluene.", Anal Chem, vol. 84, no. 9: Ionicon Analytik Gesellschaft m.b.H., Eduard-Bodem-Gasse 3, A-6020 Innsbruck, Austria., pp. 4161–4166, May, 2012.
Fears of terrorist attacks have led to the development of various technologies for the real-time detection of explosives, but all suffer from potential ambiguities in the assignment of threat agents. Using proton transfer reaction mass spectrometry (PTR-MS), an unusual bias dependence in the detection sensitivity of 2,4,6 trinitrotoluene (TNT) on the reduced electric field (E/N) has been observed. For protonated TNT, rather than decreasing signal intensity with increasing E/N, which is the more usual sensitivity pattern observed in PTR-MS studies, an anomalous behavior is first observed, whereby the signal intensity initially rises with increasing E/N. We relate this to unexpected ion-molecule chemistry based upon comparisons of measurements taken with related nitroaromatic compounds (1,3,5 trinitrobenzene, 1,3 dinitrobenzene, and 2,4 dinitrotoluene) and electronic structure calculations. This dependence provides an easily measurable signature that can be used to provide a rapid highly selective analytical procedure to minimize false positives for the detection of TNT. This has major implications for Homeland Security and, in addition, has the potential of making instrumentation cost-effective for use in security areas. This study shows that an understanding of fundamental ion-molecule chemistry occurring in low-pressure drift tubes is needed to exploit selectivity and sensitivity for analytical purposes.
[Kennedy2003] Kennedy, R. A., C. A. Mayhew, R. Thomas, and P. Watts, "Reactions of H< sub> 3 O< sup>+ with a number of bromine containing fully and partially halogenated hydrocarbons", International Journal of Mass Spectrometry, vol. 223: Elsevier, pp. 627–637, 2003.
The thermal bimolecular rate coefficients and product ion branching ratios for the reactions of H3O+ with the bromine containing molecules CH3Br, CH2Br2, CH2FBr, CHF2Br, CHFBr2, CH2BrCl, CHBrCl2, CHBr2Cl, CH3CH2Br, CH2BrCH2Cl, CH2BrCH2Br, CF3CF2Br and CF2BrCF2Br at 300 K are reported. H3O+ reacts with an experimental rate coefficient (kexp) close to the collisional value (kc≈10−9 cm3 molecule−1 s−1) with CHFBr2, CHBrCl2, CHBr2Cl, CH2BrCH2Cl, and CH2BrCH2Br, at a decreased efficiency with CH3CH2Br (kexp/kc≈0.3). The other neutral reactant molecules, CH3Br, CH2FBr, CHF2Br, CF3CF2Br, and CF2BrCF2Br react through a three-body associative process. There is no observable reaction with CH2Br2 and CH2BrCl. Mechanistic arguments are given that go some way to explaining the observed range in both reactivity and reaction pathways.
[Petersson2009] Petersson, F., P. Sulzer, C. A. Mayhew, P. Watts, A. Jordan, L. Märk, and T. D. Märk, "Real-time trace detection and identification of chemical warfare agent simulants using recent advances in proton transfer reaction time-of-flight mass spectrometry.", Rapid Commun Mass Spectrom, vol. 23, no. 23: Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria., pp. 3875–3880, Dec, 2009.
This work demonstrates for the first time the potential of using recent developments in proton transfer reaction mass spectrometry for the rapid detection and identification of chemical warfare agents (CWAs) in real-time. A high-resolution (m/Deltam up to 8000) and high-sensitivity (approximately 50 cps/ppbv) proton transfer reaction time-of-flight mass spectrometer (PTR-TOF 8000 from Ionicon Analytik GmBH) has been successfully used to detect a number of CWA simulants at room temperature; namely dimethyl methylphosphonate, diethyl methylphosphonate, diisopropyl methylphosphonate, dipropylene glycol monomethyl ether and 2-chloroethyl ethyl sulfide. Importantly, we demonstrate in this paper the potential to identify CWAs with a high level of confidence in complex chemical environments, where multiple threat agents and interferents could also be present in trace amounts, thereby reducing the risk of false positives. Instantaneous detection and identification of trace quantities of chemical threats using proton transfer reaction mass spectrometry could form the basis for a timely warning system capability with greater precision and accuracy than is currently provided by existing analytical technologies.

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Selected PTR-MS related Reviews

F. Biasioli, C. Yeretzian, F. Gasperi, T. D. Märk: PTR-MS monitoring of VOCs and BVOCs in food science and technology, Trends in Analytical Chemistry 30 (7) (2011).

J. de Gouw, C. Warneke, T. Karl, G. Eerdekens, C. van der Veen, R. Fall: Measurement of Volatile Organic Compounds in the Earth's Atmosphere using Proton-Transfer-Reaction Mass Spectrometry. Mass Spectrometry Reviews, 26 (2007), 223-257.

W. Lindinger, A. Hansel, A. Jordan: Proton-transfer-reaction mass spectrometry (PTR–MS): on-line monitoring of volatile organic compounds at pptv levels, Chem. Soc. Rev. 27 (1998), 347-375.


Lists with PTR-MS relevant publications of the University of Innsbruck can be found here: Atmospheric and indoor air chemistry, IMR, Environmental Physics and Nano-Bio-Physics


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