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Scientific Articles - PTR-MS Bibliography

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Found 9 results
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[Sulzer2013a] Sulzer, P., B. Agarwal, S. Juerschik, M. Lanza, A. Jordan, E. Hartungen, G. Hanel, L. Märk, T. D. Märk, R. González-Méndez, et al., "Applications of switching reagent ions in proton transfer reaction mass spectrometric instruments for the improved selectivity of explosive compounds", International Journal of Mass Spectrometry, vol. 354–355: Elsevier, 2013.
<p>Here we demonstrate the use of a switchable reagent ion proton transfer reaction mass spectrometry (SRI-PTR-MS) instrument to improve the instrument&#39;s selectivity for the detection of the explosive compounds 2,4,6 trinitrotoluene (TNT), 1,3,5 trinitrobenzene (TNB), pentaerythritol tetranitrate (PETN), and cyclotrimethylenetrinitramine (RDX). Selectivity is improved owing to the production of different product ions resulting from changes in the reagent ion-molecule chemistry. To be of use as an analytical tool for homeland security applications, it is important that the reagent ions (and hence product ions) can be rapidly changed (within seconds) from H3O+ to another dominant ion species if the technology is to be acceptable. This paper presents measurements that show how it is possible to rapidly switch the reagent ion from H3O+ to either O2+ or NO+ to enhance selectivity for the detection of the four explosives named above. That switching reagent ions can be done quickly results from the fact that the recombination energies of O2+ and NO+ are less than the ionisation potential of H2O, i.e. charge transfer cannot occur which otherwise would result in ions that can react efficiently with water (e.g. H2O+ + H2O &rarr; H3O+ + OH) leading to H3O+ becoming the dominant reagent ion. Reaction processes observed are non-dissociative charge transfer (O2+ with TNT and TNB), dissociative charge transfer (O2+ with TNT) and adduct formation (NO+ with PETN and RDX). O2+ is found to be unreactive with PETN and RDX, and under the conditions operating in the reaction region of the PTR-MS only a low signal associated with NO+&middot;TNT was observed. No NO+&middot;TNB was detected.</p>
[Lanza2013] Lanza, M., J. W. Acton, S. Jürschik, P. Sulzer, K. Breiev, A. Jordan, E. Hartungen, G. Hanel, L. Märk, C. A. Mayhew, et al., "Distinguishing two isomeric mephedrone substitutes with selective reagent ionisation mass spectrometry (SRI-MS)", Journal of Mass Spectrometry, vol. 48, no. 9, pp. 1015–1018, 2013.
The isomers 4-methylethcathinone and N-ethylbuphedrone are substitutes for the recently banned drug mephedrone. We find that with conventional proton transfer reaction mass spectrometry (PTR-MS), it is not possible to distinguish between these two isomers, because essentially for both substances, only the protonated molecules are observed at a mass-to-charge ratio of 192 (C12H18NO+). However, when utilising an advanced PTR-MS instrument that allows us to switch the reagent ions (selective reagent ionisation) from H3O+ (which is commonly used in PTR-MS) to NO+, O2+ and Kr+, characteristic product (fragment) ions are detected: C4H10N+ (72 Da) for 4-methylethcathinone and C5H12N+ (86 Da) for N-ethylbuphedrone; thus, selective reagent ionisation MS proves to be a powerful tool for fast detection and identification of these compounds. Copyright © 2013 John Wiley & Sons, Ltd.
[Sulzer2012c] Sulzer, P., A. Edtbauer, E. Hartungen, S. Juerschik, A. Jordan, G. Hanel, S. Feil, S. Jaksch, L. Märk, and T. D. Märk, "From conventional proton-transfer-reaction mass spectrometry (PTR-MS) to universal trace gas analysis", International Journal of Mass Spectrometry, vol. 321: Elsevier, pp. 66–70, 2012.
We present here a slightly modified PTR-MS instrument that is not only capable to ionize trace compounds in air via proton-transfer-reactions (PTR) but is also able to ionize via charge-transfer-reactions (CTR) with help of reagent ions (Kr+ in particular) possessing higher ionization energies than common air constituents. This means that with minor adaptations a common PTR-MS instrument can be used for the analysis of nearly all available substance classes by using both PTR and/or CTR ionization. Especially in environmental research, the field of application where PTR-MS is used most widely, now not only trace volatile organic compounds (benzene, toluene, etc.) but additionally also very important (inorganic) substances, such as CO, CO2, CH4, NOx, and SO2, can be detected and quantified with the same instrument. As all ionizing agents are produced in a hollow cathode discharge ion source with good purity no additional mass filter is needed for reagent ion selection (as in other analytical methods employed) and remaining reagent ion impurities can be clearly distinguished from isobaric sample compounds due to the high mass resolution of the time-of-flight mass spectrometer used in the present PTR-MS instrument (PTR-TOF 8000). We present data obtained with various gas standards ranging from a “classical” PTR-MS aromatics mixture to samples containing molecules possessing ionization energies all the way up to 14 eV (CO).
[1642] W Acton, J., M. Lanza, B. Agarwal, S. Jürschik, P. Sulzer, K. Breiev, A. Jordan, E. Hartungen, G. Hanel, L. Märk, et al., "Headspace analysis of new psychoactive substances using a Selective Reagent Ionisation-Time of Flight-Mass Spectrometer.", Int J Mass Spectrom, vol. 360, pp. 28–38, Mar, 2014.
<p>The rapid expansion in the number and use of new psychoactive substances presents a significant analytical challenge because highly sensitive instrumentation capable of detecting a broad range of chemical compounds in real-time with a low rate of false positives is required. A Selective Reagent Ionisation-Time of Flight-Mass Spectrometry (SRI-ToF-MS) instrument is capable of meeting all of these requirements. With its high mass resolution (up to m/Δm of 8000), the application of variations in reduced electric field strength (E/N) and use of different reagent ions, the ambiguity of a nominal (monoisotopic) m/z is reduced and hence the identification of chemicals in a complex chemical environment with a high level of confidence is enabled. In this study we report the use of a SRI-ToF-MS instrument to investigate the reactions of H3O(+), O2 (+), NO(+) and Kr(+) with 10 readily available (at the time of purchase) new psychoactive substances, namely 4-fluoroamphetamine, methiopropamine, ethcathinone, 4-methylethcathinone, N-ethylbuphedrone, ethylphenidate, 5-MeO-DALT, dimethocaine, 5-(2-aminopropyl)benzofuran and nitracaine. In particular, the dependence of product ion branching ratios on the reduced electric field strength for all reagent ions was investigated and is reported here. The results reported represent a significant amount of new data which will be of use for the development of drug detection techniques suitable for real world scenarios.</p>
[Maerk2012] Märk, L., A. Jordan, C. Lindinger, E. Hartungen, A. Edtbauer, S. Juerschik, P. Sulzer, and T. D. Märk, "More than one order of magnitude higher sensitivities with Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry", : IONICON Analytik, 2012.
[Hartungen2013] Hartungen, E., S. Juerschik, A. Jordan, A. Edtbauer, S. Feil, G. Hanel, H. Seehauser, S. Haidacher, R. Schottkowsky, L. Märk, et al., "Proton transfer reaction-mass spectrometry: fundamentals, recent advances and applications", The European Physical Journal Applied Physics, vol. 61, no. 02: Cambridge Univ Press, pp. 24303, 2013.
Proton transfer reaction-mass spectrometry (PTR-MS) offers many advantages for trace gas analysis, including no sample preparation, real-time analysis, high selectivity and sensitivity, ultra-low detection limits and very short response times. These characteristic features have made it an ideal tool for many applications in science, technology and society. Here we will discuss recent developments, in particular advances concerning sensitivity, selectivity and general applicability.
[Lindinger2013] Lindinger, C., L. Märk, P. Sulzer, S. Juerschik, B. Agarwal, C. A. Mayhew, and T. D. Märk, "Proton-Transfer-Reaction Mass Spectrometry: Increased Selectivity in Explosives and Designer Drugs Detection", : IONICON Analytik, 2013.
[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.
[1638] Lanza, M., J. W Acton, P. Sulzer, K. Breiev, S. Jürschik, A. Jordan, E. Hartungen, G. Hanel, L. Märk, T. D. Märk, et al., "Selective reagent ionisation-time of flight-mass spectrometry: a rapid technology for the novel analysis of blends of new psychoactive substances.", J Mass Spectrom, vol. 50, pp. 427–431, Feb, 2015.
<p>In this study we demonstrate the potential of selective reagent ionisation-time of flight-mass spectrometry for the rapid and selective identification of a popular new psychoactive substance blend called &#39;synthacaine&#39;, a mixture that is supposed to imitate the sensory and intoxicating effects of cocaine. Reactions with H3O(+) result in protonated parent molecules which can be tentatively assigned to benzocaine and methiopropamine. However, by comparing the product ion branching ratios obtained at two reduced electric field values (90 and 170 Td) for two reagent ions (H3O(+) and NO(+)) to those of the pure chemicals, we show that identification is possible with a much higher level of confidence then when relying solely on the m/z of protonated parent molecules. A rapid and highly selective analytical identification of the constituents of a recreational drug is particularly crucial to medical personnel for the prompt medical treatment of overdoses, toxic effects or allergic reactions.</p>

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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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