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Found 5 results
Title [ Year(Desc)]
Filters: Author is Philipp Eichler  [Clear All Filters]
2015
[1825] Eichler, P., M. Müller, B. D{\textquotesingle}Anna, and A. Wisthaler, "A novel inlet system for online chemical analysis of semi-volatile submicron particulate matter", Atmospheric Measurement Techniques, vol. 8, pp. 1353–1360, mar, 2015.
Link: https://www.atmos-meas-tech.net/8/1353/2015/
Abstract
<p>We herein present a novel modular inlet system designed to be coupled to low-pressure gas analyzers for online chemical characterization of semi-volatile submicron particles. The &quot;chemical analysis of aerosol online&quot; (CHARON) inlet consists of a gas-phase denuder for stripping off gas-phase analytes, an aerodynamic lens for particle collimation combined with an inertial sampler for the particle-enriched flow and a thermodesorption unit for particle volatilization prior to chemical analysis. The denuder was measured to remove gas-phase organics with an efficiency &gt; 99.999% and to transmit particles in the 100&ndash;750 nm size range with a 75&ndash;90% efficiency. The measured average particle enrichment factor in the subsampling flow from the aerodynamic lens was 25.6, which is a factor of 3 lower than the calculated theoretical optimum. We coupled the CHARON inlet to a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) which quantitatively detects most organic analytes and ammonia. The combined CHARON-PTR-ToF-MS setup is thus capable of measuring both the organic and the ammonium fraction in submicron particles in real time. Individual organic compounds can be detected down to levels of 10&ndash;20 ng m&minus;3. Two proof-of-principle studies were carried out for demonstrating the analytical power of this new instrumental setup: (i) oxygenated organics and their partitioning between the gas and the particulate phase were observed from the reaction of limonene with ozone and (ii) nicotine was measured in cigarette smoke particles demonstrating that selected organic target compounds can be detected in submicron particles in real time.</p>
2017
[1833] Müller, M., P. Eichler, B. D'Anna, W. Tan, and A. Wisthaler, "Direct Sampling and Analysis of Atmospheric Particulate Organic Matter by Proton-Transfer-Reaction Mass Spectrometry", Analytical Chemistry, sep, 2017.
Link: http://pubs.acs.org/doi/10.1021/acs.analchem.7b02582
Abstract
<p>We report on a new method for analyzing atmospheric submicrometer particulate organic matter which combines direct particle sampling and volatilization with online chemical ionization mass spectrometric analysis. Technically, the method relies on the combined use of a CHARON (&ldquo;Chemical Analysis of Aerosol Online&rdquo;) particle inlet and a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS). Laboratory studies on target analytes showed that the ionization conditions in the PTR-ToF-MS lead to extensive fragmentation of levoglucosan and cis-pinonic acid, while protonated oleic acid and 5α-cholestane molecules remain intact. Potential problems and biases in quantitative and qualitative analyses are discussed. Side-by-side atmospheric comparison measurements of total particulate organic mass and levoglucosan with an aerosol mass spectrometer (AMS) were in good agreement. Complex and clearly distinct organic mass spectra were obtained from atmospheric measurements in three European cities (Lyon, Valencia, Innsbruck). Data visualization in reduced-parameter frameworks (e.g., oxidation state of carbon vs carbon number) revealed that the CHARON-PTR-ToF-MS technique adds significant analytical capabilities for characterizing particulate organic carbon in the Earth&rsquo;s atmosphere. Positive matrix factorization (PMF) was used for apportioning sources of atmospheric particles in late fall in Innsbruck. The m/z signatures of known source marker compounds (levoglucosan and resin acids, polycyclic aromatic hydrocarbons, nicotine) in the mass spectra were used to assign PMF factors to biomass burning, traffic, and smoking emission sources.</p>
[1824] Eichler, P., M. Müller, C. Rohmann, B. Stengel, J. Orasche, R. Zimmermann, and A. Wisthaler, "Lubricating Oil as a Major Constituent of Ship Exhaust Particles", Environmental Science {&} Technology Letters, vol. 4, pp. 54–58, jan, 2017.
Link: http://pubs.acs.org/doi/abs/10.1021/acs.estlett.6b00488
Abstract
<p>A proton-transfer-reaction time-of-flight mass spectrometer combined with the novel CHARON (&ldquo;chemical analysis of aerosol online&rdquo;) aerosol inlet was used for characterization of submicrometer particulate organic matter in ship engine exhaust. Particles were sampled from diluted and cooled exhaust of a marine test bench engine that was operated on residual heavy fuel oil (HFO) and low-sulfur distillate marine gas oil (MGO), respectively. In both fuel operation modes, exhaust particle mass spectra were dominated by polycycloalkanes in the C20-to-C39 range, which are typical main constituents of lubricating oils. Exhaust particle mass spectra were closely reproduced when the engine&rsquo;s lubricant oil was directly measured in aerosolized form. We report emission profiles of lubricant oil hydrocarbons as a function of their volatility and as a function of their carbon atom number. Total emissions of lubricant oil amounted to 183 and 74 mg kW&ndash;1 h&ndash;1 for HFO and MGO combustion, respectively. These values resemble typical oil loss rates of marine four-stroke trunk piston engines in which most of the lubricant is known to be lost through the combustion chamber and the tailpipe. We conclude that marine trunk piston engines are generally prone to high emissions of particles mainly composed of unburned lubricating oil.</p>
2018
[1864] Gkatzelis, G. I., R. Tillmann, T. Hohaus, M. Müller, P. Eichler, K-M. Xu, P. Schlag, S. H. Schmitt, R. Wegener, M. Kaminski, et al., "Comparison of three aerosol chemical characterization techniques utilizing {PTR}-{ToF}-{MS}: a study on freshly formed and aged biogenic {SOA}", Atmospheric Measurement Techniques, vol. 11, pp. 1481–1500, mar, 2018.
Link: https://www.atmos-meas-tech.net/11/1481/2018/amt-11-1481-2018.html
Abstract
<p>An intercomparison of different aerosol chemical characterization techniques has been performed as part of a chamber study of biogenic secondary organic aerosol (BSOA) formation and aging at the atmosphere simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a large Reaction chamber). Three different aerosol sampling techniques &ndash; the aerosol collection module (ACM), the chemical analysis of aerosol online (CHARON) and the collection thermal-desorption unit (TD) were connected to proton transfer reaction time-of-flight mass spectrometers (PTR-ToF-MSs) to provide chemical characterization of the SOA. The techniques were compared among each other and to results from an aerosol mass spectrometer (AMS) and a scanning mobility particle sizer (SMPS). The experiments investigated SOA formation from the ozonolysis of β-pinene, limonene, a β-pinene&ndash;limonene mix and real plant emissions from Pinus sylvestris L. (Scots pine). The SOA was subsequently aged by photo-oxidation, except for limonene SOA, which was aged by NO3 oxidation. Despite significant differences in the aerosol collection and desorption methods of the PTR-based techniques, the determined chemical composition, i.e. the same major contributing signals, was found by all instruments for the different chemical systems studied. These signals could be attributed to known products expected from the oxidation of the examined monoterpenes. The sampling and desorption method of ACM and TD provided additional information on the volatility of individual compounds and showed relatively good agreement. Averaged over all experiments, the total aerosol mass recovery compared to an SMPS varied within 80 &plusmn; 10, 51 &plusmn; 5 and 27 &plusmn; 3 % for CHARON, ACM and TD, respectively. Comparison to the oxygen-to-carbon ratios (O : C) obtained by AMS showed that all PTR-based techniques observed lower O : C ratios, indicating a loss of molecular oxygen either during aerosol sampling or detection. The differences in total mass recovery and O : C between the three instruments resulted predominantly from differences in the field strength (E∕N) in the drift tube reaction ionization chambers of the PTR-ToF-MS instruments and from dissimilarities in the collection/desorption of aerosols. Laboratory case studies showed that PTR-ToF-MS E∕N conditions influenced fragmentation which resulted in water and further neutral fragment losses of the detected molecules. Since ACM and TD were operated in higher E∕N than CHARON, this resulted in higher fragmentation, thus affecting primarily the detected oxygen and carbon content and therefore also the mass recovery. Overall, these techniques have been shown to provide valuable insight on the chemical characteristics of BSOA and can address unknown thermodynamic properties such as partitioning coefficient values and volatility patterns down to a compound-specific level.</p>
[1863] Tan, W., L. Zhu, T. Mikoviny, C. J. Nielsen, A. Wisthaler, P. Eichler, M. Müller, B. D'Anna, N. J. Farren, J. F. Hamilton, et al., "Theoretical and Experimental Study on the Reaction of tert-Butylamine with {OH} Radicals in the Atmosphere", The Journal of Physical Chemistry A, vol. 122, pp. 4470–4480, apr, 2018.
Link: https://www.atmos-meas-tech.net/11/1481/2018/amt-11-1481-2018.html
Abstract
<p>The OH-initiated atmospheric degradation of tert-butylamine (tBA), (CH3)3CNH2, was investigated in a detailed quantum chemistry study and in laboratory experiments at the European Photoreactor (EUPHORE) in Spain. The reaction was found to mainly proceed via hydrogen abstraction from the amino group, which in the presence of nitrogen oxides (NOx), generates tert-butylnitramine, (CH3)3CNHNO2, and acetone as the main reaction products. Acetone is formed via the reaction of tert-butylnitrosamine, (CH3)3CNHNO, and/or its isomer tert-butylhydroxydiazene, (CH3)3CN═NOH, with OH radicals, which yield nitrous oxide (N2O) and the (CH3)3Ċ radical. The latter is converted to acetone and formaldehyde. Minor predicted and observed reaction products include formaldehyde, 2-methylpropene, acetamide and propan-2-imine. The reaction in the EUPHORE chamber was accompanied by strong particle formation which was induced by an acid&ndash;base reaction between photochemically formed nitric acid and the reagent amine. The tert-butylaminium nitrate salt was found to be of low volatility, with a vapor pressure of 5.1 &times; 10&ndash;6 Pa at 298 K. The rate of reaction between tert-butylamine and OH radicals was measured to be 8.4 (&plusmn;1.7) &times; 10&ndash;12 cm3 molecule&ndash;1 s&ndash;1 at 305 &plusmn; 2 K and 1015 &plusmn; 1 hPa.</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).
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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.
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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.
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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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