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Röhler, Laura, Martin Schlabach, Peter Haglund, Knut Breivik, Roland Kallenborn i Pernilla Bohlin-Nizzetto. "Non-target and suspect characterisation of organic contaminants in Arctic air – Part 2: Application of a new tool for identification and prioritisation of chemicals of emerging Arctic concern in air". Atmospheric Chemistry and Physics 20, nr 14 (29.07.2020): 9031–49. http://dx.doi.org/10.5194/acp-20-9031-2020.
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Abstract. The Norwegian Arctic possesses a unique environment for the detection of new potential chemicals of emerging Arctic concern (CEACs) due to remoteness, sparse population and the low number of local contamination sources. Hence, a contaminant present in Arctic air is still considered a priority indication for its environmental stability and environmental mobility. Today, legacy persistent organic pollutants (POPs) and related conventional environmental pollutants are already well-studied because of their identification as Arctic pollutants in the 1980s. Many of them are implemented and reported in various national and international monitoring activities including the Arctic Monitoring and Assessment Programme (AMAP). These standard monitoring schemes, however, are based on compound-specific quantitative analytical methods. Under such conditions, the possibility for the identification of hitherto unidentified contaminants is limited and random at best. Today, new and advanced technological developments allow a broader, unspecific analytical approach as either targeted multicomponent analysis or suspect and non-target screening strategies. In order to facilitate such a wide range of compounds, a wide-scope sample clean-up method for high-volume air samples based on a combination of adsorbents was applied, followed by comprehensive two-dimensional gas chromatography separation and low-resolution time-of-flight mass spectrometric detection (GC × GC-LRMS). During the study reported here, simultaneous non-target and suspect screening were applied. The detection of over 700 compounds of interest in the particle phase and over 1200 compounds in the gaseous phase is reported. Of those, 62 compounds were confirmed with reference standards and 90 compounds with a probable structure (based upon mass spectrometric interpretation and library spectrum comparison). These included compounds already detected in Arctic matrices and compounds not detected previously (see also Fig. 1). In addition, 241 compounds were assigned a tentative structure or compound class. Hitherto unknown halogenated compounds, which are not listed in the mass spectral libraries used, were also detected and partly identified.
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Brüggemann, Martin, Laurent Poulain, Andreas Held, Torsten Stelzer, Christoph Zuth, Stefanie Richters, Anke Mutzel i in. "Real-time detection of highly oxidized organosulfates and BSOA marker compounds during the F-BEACh 2014 field study". Atmospheric Chemistry and Physics 17, nr 2 (31.01.2017): 1453–69. http://dx.doi.org/10.5194/acp-17-1453-2017.
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Abstract. The chemical composition of ambient organic aerosols was analyzed using complementary mass spectrometric techniques during a field study in central Europe in July 2014 (Fichtelgebirge – Biogenic Emission and Aerosol Chemistry, F-BEACh 2014). Among several common biogenic secondary organic aerosol (BSOA) marker compounds, 93 acidic oxygenated hydrocarbons were detected with elevated abundances and were thus attributed to be characteristic for the organic aerosol mass at the site. Monoterpene measurements exhibited median mixing ratios of 1.6 and 0.8 ppbV for in and above canopy levels respectively. Nonetheless, concentrations for early-generation oxidation products were rather low, e.g., pinic acid (c = 4.7 (±2.5) ng m−3). In contrast, high concentrations were found for later-generation photooxidation products such as 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA, c = 13.8 (±9.0) ng m−3) and 3-carboxyheptanedioic acid (c = 10.2 (±6.6) ng m−3), suggesting that aged aerosol masses were present during the campaign period. In agreement, HYSPLIT trajectory calculations indicate that most of the arriving air masses traveled long distances (> 1500 km) over land with high solar radiation. In addition, around 47 % of the detected compounds from filter sample analysis contained sulfur, confirming a rather high anthropogenic impact on biogenic emissions and their oxidation processes. Among the sulfur-containing compounds, several organosulfates, nitrooxy organosulfates, and highly oxidized organosulfates (HOOS) were tentatively identified by high-resolution mass spectrometry. Correlations among HOOS, sulfate, and highly oxidized multifunctional organic compounds (HOMs) support the hypothesis of previous studies that HOOS are formed by reactions of gas-phase HOMs with particulate sulfate. Moreover, periods with high relative humidity indicate that aqueous-phase chemistry might play a major role in HOOS production. However, for dryer periods, coinciding signals for HOOS and gas-phase peroxyradicals (RO2•) were observed, suggesting RO2• to be involved in HOOS formation.
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Zogka, Antonia G., Manolis N. Romanias i Frederic Thevenet. "Formaldehyde and glyoxal measurement deploying a selected ion flow tube mass spectrometer (SIFT-MS)". Atmospheric Measurement Techniques 15, nr 7 (5.04.2022): 2001–19. http://dx.doi.org/10.5194/amt-15-2001-2022.
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Abstract. Formaldehyde (FM) and glyoxal (GL) are important atmospheric species of indoor and outdoor environments. They are either directly emitted in the atmosphere, or they are formed through the oxidation of organic compounds by indoor and/or outdoor atmospheric oxidants. Despite their importance, the real-time monitoring of these compounds with soft ionization mass spectrometric techniques, e.g., proton transfer mass spectrometry (PTR-MS), remains problematic and is accompanied by low sensitivity. In this study, we evaluate the performance of a multi-ion selected ion flow tube mass spectrometer (SIFT-MS) to monitor in real-time atmospherically relevant concentrations of FM and GL under controlled experimental conditions. The SIFT-MS used is operated under standard conditions (SCs), as proposed by the supplier, and custom conditions (CCs) to achieve higher sensitivity. In the case of FM, SIFT-MS sensitivity is marginally impacted by relative humidity (RH), and the detection limits achieved are below 200 ppt (parts per trillion). Contrariwise, in the case of GL, a sharp decrease of instrument sensitivity is observed with increasing RH when the H3O+ ion is used. Nevertheless, the detection of GL, using NO+ precursor ion, is moderately impacted by moisture with an actual positive sensitivity response. Therefore, we recommend the use of the NO+ precursor for the reliable detection and quantitation of GL. This work evidences that SIFT-MS can be considered as an efficient tool to monitor the concentration of FM and GL in laboratory experiments, and potentially in indoor or outdoor environments, capable of identifying their primary emission or secondary formation through (photo)oxidation processes. Furthermore, SIFT-MS technology still allows great possibilities for sensitivity improvement and high potential for monitoring low proton transfer affinity compounds.
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Ahn, Yun Gyong, So Hyeon Jeon, Hyung Bae Lim, Na Rae Choi, Geum-Sook Hwang, Yong Pyo Kim i Ji Yi Lee. "Analysis of Polycyclic Aromatic Hydrocarbons in Ambient Aerosols by Using One-Dimensional and Comprehensive Two-Dimensional Gas Chromatography Combined with Mass Spectrometric Method: A Comparative Study". Journal of Analytical Methods in Chemistry 2018 (2018): 1–9. http://dx.doi.org/10.1155/2018/8341630.
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Advanced separation technology paired with mass spectrometry is an ideal method for the analysis of atmospheric samples having complex chemical compositions. Due to the huge variety of both natural and anthropogenic sources of organic compounds, simultaneous quantification and identification of organic compounds in aerosol samples represents a demanding analytical challenge. In this regard, comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) has become an effective analytical method. However, verification and validation approaches to quantify these analytes have not been critically evaluated. We compared the performance of gas chromatography with quadrupole mass spectrometry (GC-qMS) and GC×GC-TOFMS for quantitative analysis of eighteen target polycyclic aromatic hydrocarbons (PAHs). The quantitative obtained results such as limits of detection (LODs), limits of quantification (LOQs), and recoveries of target PAHs were approximately equivalent based on both analytical methods. Furthermore, a larger number of analytes were consistently identified from the aerosol samples by GC×GC-TOFMS compared to GC-qMS. Our findings suggest that GC×GC-TOFMS would be widely applicable to the atmospheric and related sciences with simultaneous target and nontarget analysis in a single run.
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Rincón, Angela G., Ana I. Calvo, Mathias Dietzel i Markus Kalberer. "Seasonal differences of urban organic aerosol composition – an ultra-high resolution mass spectrometry study". Environmental Chemistry 9, nr 3 (2012): 298. http://dx.doi.org/10.1071/en12016.
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Environmental contextUnderstanding the molecular composition and chemical transformations of organic aerosols during atmospheric aging is a major challenge in atmospheric chemistry. Ultra-high resolution mass spectrometry can provide detailed information on the molecular composition of organic aerosols. Aerosol samples collected in summer and winter at an urban site are characterised and compared in detail with respect to the elemental composition of their components, especially nitrogen- and sulfur-containing compounds, and are discussed with respect to atmospheric formation processes. AbstractOrganic compounds are major constituents of atmospheric aerosol particles. The understanding of their chemical composition, their properties and reactivity are important for assessing aerosol effects upon both global climate change and human health. The composition of organic aerosols is poorly understood, mainly due to its highly complex chemical composition of several thousand compounds. There is currently no analytical technique available covering a wide enough chemical space to characterise this large number of organic compounds. In recent years ultra-high resolution mass spectrometry has been increasingly used to explore the chemical complexity in organic aerosols from laboratory and ambient samples. In the present study ambient particles <1 µm were collected at an urban site in Cambridge, UK, from August to December 2009. The water-soluble organic fraction of the filters was separated from inorganic ions following a procedure developed for humic-like substance isolation. Ultra-high resolution mass spectrometry analyses were performed in negative and positive polarity. Data in the mass range of m/z 50–350 were analysed for their elemental composition. Summer samples generally contained more components than winter samples. The large number of compounds was subdivided into groups according to their elemental composition. Up to 80 % of the peaks contain nitrogen and sulfur functional groups and only ~20 % of the compounds contain only C, H and O atoms. In summer the fraction of compounds with oxidised nitrogen and sulfur groups increases compared with winter indicating a photo-chemical formation route of these multifunctional compounds. In addition to oxidised nitrogen compounds a large number of amines was identified.
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Schneider, J., S. Borrmann, A. G. Wollny, M. Bläsner, N. Mihalopoulos, K. Oikonomou, J. Sciare, A. Teller, Z. Levin i D. R. Worsnop. "Online mass spectrometric aerosol measurements during the MINOS campaign (Crete, August 2001)". Atmospheric Chemistry and Physics 4, nr 1 (23.01.2004): 65–80. http://dx.doi.org/10.5194/acp-4-65-2004.
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Abstract. Mass spectrometric analysis of volatile and semi-volatile (=non-refractory) aerosol particles have been performed during a field study in the summer Eastern Mediterranean. A size-resolved, quantitative mass spectrometric technique (the Aerodyne Aerosol Mass Spectrometer, AMS) has been used, and the results are compared to filter sampling methods and particle sizing techniques. The different techniques agree with the finding that the fine particle mode (D<1.2 mm) consisted mostly of ammonium sulfate and of organic material. The aerosol sulfate ranged between 2 and 12 mg/m3. On most days, ammonium was closely correlated with sulfate, suggesting ammonium sulfate as the major aerosol component, but on days with high sulfate mass concentrations, the sulfate was not fully neutralized by ammonium. Trajectories indicate that the aerosol and/or its precursors originate from South-Eastern Europe. The source of the ammonium sulfate aerosol is most likely fossil fuel burning, whereas the organic aerosol may also originate from biomass burning. Ion series analysis of the organics fraction in the mass spectrometer indicated that the major component of the organics were oxygenated organics which are a marker for aged, photochemically processed aerosol or biomass burning aerosol. The non-refractory aerosol compounds, measured with the Aerosol Mass Spectrometer, contributed between 37 and 50% to the total aerosol mass in the fine mode. A second mass spectrometer for single particle analysis by laser ablation has been used for the first time in the field during this study and yielded results, which agree with filter samples of the coarse particle mode. This mode consisted of sea salt particles and dust aerosol.
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Alsaggaf, Wejdan T. "The Chemistry of Paper in Paper Spray Ionization Mass Spectrometry". International Journal of Chemistry 12, nr 1 (10.10.2019): 16. http://dx.doi.org/10.5539/ijc.v12n1p16.
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There are many rapidly evolving technologies that use simple papers as a surface for chemical reactions and detection of molecules. One example of this application is the use of paper as a surface for ionization and introduction of compounds into mass spectrometry. The current work was designed to investigate mechanisms of interaction between the paper and analytes using mass spectrometry as the detection instrument. Standard compounds with different sizes were used in this study. Factors investigated include the effects of the paper geometry (5 mm) and position (tp=90º) were found to be optimal. The role of atmospheric water and the effects of paper porosity were affected the signals of the tested compounds. Investigations of the interaction of standard solutions with the paper surface indicated that atmospheric water is required for ionization. Up to three water molecules were detected in association with the analytes indicating that the presence of some water is required. In addition, this study showed the potential of silicon dioxide nanoparticles for eluting the standards compound from the paper surface. The impact of trace elements in the commercial papers and the interactions between the paper cellulose with different classes of analytes was investigated.
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Müller, L., M. C. Reinnig, K. H. Naumann, H. Saathoff, T. F. Mentel, N. M. Donahue i T. Hoffmann. "Formation of 3-methyl-1,2,3-butanetricarboxylic acid via gas phase oxidation of pinonic acid – a mass spectrometric study of SOA aging". Atmospheric Chemistry and Physics 12, nr 3 (8.02.2012): 1483–96. http://dx.doi.org/10.5194/acp-12-1483-2012.
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Abstract. This paper presents the results of mass spectrometric investigations of the OH-initiated oxidative aging of α-pinene SOA under simulated tropospheric conditions at the large aerosol chamber facility AIDA, Karlsruhe Institute of Technology. In particular, the OH-initiated oxidation of pure pinic and pinonic acid, two well-known oxidation products of α-pinene, was investigated. Two complementary analytical techniques were used, on-line atmospheric pressure chemical ionization/mass spectrometry (APCI/MS) and filter sampling followed by liquid chromatography/mass spectrometry (LC/ESI-MS). The results show that 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a very low volatile α-pinene SOA product and a tracer compound for terpene SOA, is formed from the oxidation of pinonic acid and that this oxidation takes place in the gas phase. This finding is confirmed by temperature-dependent aging experiments on whole SOA formed from α-pinene, in which the yield of MBTCA scales with the pinonic acid fraction in the gas phase. Based on the results, several feasible gas-phase radical mechanisms are discussed to explain the formation of MBTCA from OH-initiated pinonic acid oxidation.
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Khasanov, U., SS Iskhakova i DT Usmanov. "Examination of the effect of air atmosphere on heterogeneous reactions under surface ionization of psychotropic drug molecules". European Journal of Mass Spectrometry 26, nr 6 (grudzień 2020): 409–18. http://dx.doi.org/10.1177/1469066720976016.
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The results of mass spectrometric studies of surface ionization of molecules of psychotropic drugs such as chlorpromazine, amitriptyline and medazepam in an air atmosphere have been presented. The channels of heterogeneous reactions occurring during the molecule adsorption on the hot surface of the thermoemitter from refractory metal oxides have been revealed, as well as the influence of air atmosphere on these reactions. A strong influence of the air atmosphere on the heterogeneous association reactions with the emission of [M + H]+ ions has been found. This ion line is the main in the mass spectra of all the substances under study instead of the characteristic main line in the surface ionization mass spectra obtained in vacuum. The effect of air on the reactions of dehydrogenation and dissociation of adsorbed molecules of organic compounds has been insignificant. In the surface ionization mass spectra of all the substances studied under atmospheric conditions the adduct cluster ions М⋅[М−R]+, М⋅[М−Н]+ and М⋅[М+Н]+ (where М is the molecule, R is the radical, H is the hydrogen atom) up to М⋅[М+Н]+⋅HCl. They are probably formed by adhesion of analyte molecules to the primary ions [М−R]+, [М−Н]+ and [М+Н]+. A comparative analysis has been also performed with the data obtained by chromato-mass spectrometry with electron ionization, as well as with the surface ionization data for these preparations obtained under high vacuum.
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Riva, Matthieu, Pekka Rantala, Jordan E. Krechmer, Otso Peräkylä, Yanjun Zhang, Liine Heikkinen, Olga Garmash i in. "Evaluating the performance of five different chemical ionization techniques for detecting gaseous oxygenated organic species". Atmospheric Measurement Techniques 12, nr 4 (17.04.2019): 2403–21. http://dx.doi.org/10.5194/amt-12-2403-2019.
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Abstract. The impact of aerosols on climate and air quality remains poorly understood due to multiple factors. One of the current limitations is the incomplete understanding of the contribution of oxygenated products, generated from the gas-phase oxidation of volatile organic compounds (VOCs), to aerosol formation. Indeed, atmospheric gaseous chemical processes yield thousands of (highly) oxygenated species, spanning a wide range of chemical formulas, functional groups and, consequently, volatilities. While recent mass spectrometric developments have allowed extensive on-line detection of a myriad of oxygenated organic species, playing a central role in atmospheric chemistry, the detailed quantification and characterization of this diverse group of compounds remains extremely challenging. To address this challenge, we evaluated the capability of current state-of-the-art mass spectrometers equipped with different chemical ionization sources to detect the oxidation products formed from α-Pinene ozonolysis under various conditions. Five different mass spectrometers were deployed simultaneously for a chamber study. Two chemical ionization atmospheric pressure interface time-of-flight mass spectrometers (CI-APi-TOF) with nitrate and amine reagent ion chemistries and an iodide chemical ionization time-of-flight mass spectrometer (TOF-CIMS) were used. Additionally, a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF 8000) and a new “vocus” PTR-TOF were also deployed. In the current study, we compared around 1000 different compounds between each of the five instruments, with the aim of determining which oxygenated VOCs (OVOCs) the different methods were sensitive to and identifying regions where two or more instruments were able to detect species with similar molecular formulae. We utilized a large variability in conditions (including different VOCs, ozone, NOx and OH scavenger concentrations) in our newly constructed atmospheric simulation chamber for a comprehensive correlation analysis between all instruments. This analysis, combined with estimated concentrations for identified molecules in each instrument, yielded both expected and surprising results. As anticipated based on earlier studies, the PTR instruments were the only ones able to measure the precursor VOC, the iodide TOF-CIMS efficiently detected many semi-volatile organic compounds (SVOCs) with three to five oxygen atoms, and the nitrate CI-APi-TOF was mainly sensitive to highly oxygenated organic (O > 5) molecules (HOMs). In addition, the vocus showed good agreement with the iodide TOF-CIMS for the SVOC, including a range of organonitrates. The amine CI-APi-TOF agreed well with the nitrate CI-APi-TOF for HOM dimers. However, the loadings in our experiments caused the amine reagent ion to be considerably depleted, causing nonlinear responses for monomers. This study explores and highlights both benefits and limitations of currently available chemical ionization mass spectrometry instrumentation for characterizing the wide variety of OVOCs in the atmosphere. While specifically shown for the case of α-Pinene ozonolysis, we expect our general findings to also be valid for a wide range of other VOC–oxidant systems. As discussed in this study, no single instrument configuration can be deemed better or worse than the others, as the optimal instrument for a particular study ultimately depends on the specific target of the study.
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Fresnais, Margaux, Siwen Liang, Marius Breitkopf, Joshua Raoul Lindner, Emmanuelle Claude, Steven Pringle, Pavel A. Levkin i in. "Analytical Performance Evaluation of New DESI Enhancements for Targeted Drug Quantification in Tissue Sections". Pharmaceuticals 15, nr 6 (1.06.2022): 694. http://dx.doi.org/10.3390/ph15060694.
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Desorption/ionization (DI)-mass spectrometric (MS) methods offer considerable advantages of rapidity and low-sample input for the analysis of solid biological matrices such as tissue sections. The concept of desorption electrospray ionization (DESI) offers the possibility to ionize compounds from solid surfaces at atmospheric pressure, without the addition of organic compounds to initiate desorption. However, severe drawbacks from former DESI hardware stability made the development of assays for drug quantification difficult. In the present study, the potential of new prototype source setups (High Performance DESI Sprayer and Heated Transfer Line) for the development of drug quantification assays in tissue sections was evaluated. It was demonstrated that following dedicated optimization, new DESI XS enhancements present promising options regarding targeted quantitative analyses. As a model compound for these developments, ulixertinib, an inhibitor of extracellular signal-regulated kinase (ERK) 1 and 2 was used.
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Alfarra, M. R., D. Paulsen, M. Gysel, A. A. Garforth, J. Dommen, A. S. H. Prévôt, D. R. Worsnop, U. Baltensperger i H. Coe. "A mass spectrometric study of secondary organic aerosols formed from the photooxidation of anthropogenic and biogenic precursors in a reaction chamber". Atmospheric Chemistry and Physics 6, nr 12 (20.11.2006): 5279–93. http://dx.doi.org/10.5194/acp-6-5279-2006.
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Abstract. An Aerodyne Aerosol Mass Spectrometer (AMS) has been utilised to provide on-line measurements of the mass spectral signatures and mass size distributions of the oxidation products resulting from irradiating 1,3,5-trimethylbenzene (1,3,5-TMB) and α-pinene, separately, in the presence of nitrogen oxide, nitrogen dioxide and propene in a reaction chamber. Mass spectral results indicate that both precursors produce SOA with broadly similar chemical functionality of a highly oxidised nature. However, significant differences occur in the minor mass spectral fragments for the SOA in the two reaction systems, indicating that they have different molecular composition. Nitrogen-containing organic compounds have been observed in the photooxidation products of both precursors, and their formation appeared to be controlled by the temporal variability of NOx. Although the overall fragmentation patterns of the photooxidation products in both systems did not change substantially over the duration of each experiment, the contribution of some individual mass fragments to total mass appeared to be influenced by the irradiation time. The effective densities of the 1,3,5-TMB and α-pinene SOA particles were determined for various particle sizes using the relationship between mobility and vacuum aerodynamic diameters. The effective density for the 1,3,5-TMB SOA ranged from 1.35–1.40 g/cm3, while that for α-pinene SOA ranged from 1.29–1.32 g/cm3. The determined effective densities did not show dependence on irradiation time. Results suggest that further chemical processing of SOA takes place in the real atmosphere, as neither the α-pinene nor the 1,3,5-TMB experimental results reproduce the right relative product distribution between carbonyl-containing and multifunctional carboxylic acid species measured at ambient locations influenced by aged continental organic aerosols.
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An, Yanqing, Jianzhong Xu, Lin Feng, Xinghua Zhang, Yanmei Liu, Shichang Kang, Bin Jiang i Yuhong Liao. "Molecular characterization of organic aerosol in the Himalayas: insight from ultra-high-resolution mass spectrometry". Atmospheric Chemistry and Physics 19, nr 2 (29.01.2019): 1115–28. http://dx.doi.org/10.5194/acp-19-1115-2019.
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Abstract. An increased trend in aerosol concentration has been observed in the Himalayas in recent years, but the understanding of the chemical composition and sources of aerosol remains poorly understood. In this study, molecular chemical composition of water-soluble organic matter (WSOM) from two filter samples collected during two high aerosol loading periods (denoted as P1 and P2) at a high-altitude station (Qomolangma Station, QOMS; 4276 m a.s.l.) in the northern Himalayas was identified using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR MS). More than 4000 molecular formulas were identified in each filter sample which were classified into two compound groups (CHO and CHON) based on their elemental composition, with both accounting for nearly equal contributions in number (45 %–55 %). The relative abundance weighted mole ratio of O∕Cw for P1 and P2 was 0.43 and 0.39, respectively, and the weighted double bond equivalents (DBEw), an index for the saturation of organic molecules, were 7.12 and 7.87, respectively. Although the O∕Cw mole ratio was comparable for CHO and CHON compounds, the DBEw was significantly higher in CHON compounds than CHO compounds. More than 50 % molecular formulas in the Van Krevelen (VK) diagram (H∕C vs. O∕C) were located in 1–1.5 (H∕C) and 0.2–0.6 (O∕C) regions, suggesting potential lignin-like compounds. The distributions of CHO and CHON compounds in the VK diagram, DBE vs. number of C atoms, and other diagnostic diagrams showed high similarities among each other, suggesting their similar source and/or atmospheric processes. Many formulas formed from biogenic volatile organic compounds (e.g., ozonolysis of α-pinene products) and biomass-burning-emitted compounds (e.g., phenolic compounds) were found in the WSOM, suggesting the important contribution of these two sources in the Himalayas. The high DBE and high fraction of nitrogen-containing aerosol can potentially impact aerosol light absorption in this remote region. Further comprehensive study is needed due to the complexity of organic aerosol and limited molecular number identified in this study.
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Schmitt-Kopplin, P., G. Liger-Belair, B. P. Koch, R. Flerus, G. Kattner, M. Harir, B. Kanawati i in. "Dissolved organic matter in sea spray: a transfer study from marine surface water to aerosols". Biogeosciences Discussions 8, nr 6 (8.12.2011): 11767–93. http://dx.doi.org/10.5194/bgd-8-11767-2011.
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Abstract. Atmospheric aerosols impose direct and indirect effects on the climate system, for example, by adsorption of radiation in relation to cloud droplets size, on chemical and organic composition and cloud dynamics. The first step in the formation of primary marine aerosols, i.e., the transfer of dissolved organic matter from the marine surface into the atmosphere was studied, and we present a molecular level description of this phenomenon using high resolution analytical tools (Fourier transform ion cyclotron resonance = FT-ICR MS and NMR). We could experimentally confirm the chemo-selective transfer of natural organic molecules, especially of aliphatic compounds from the surface water into the atmosphere via bubble bursting processes. Transfer from marine surface water to the atmosphere involves a chemical gradient governed by the physicochemical properties of the involved molecules when comparing elemental compositions and differentiating CHO, CHNO, CHOS and CHNOS bearing compounds. Typical chemical fingerprints of concentrated compounds were CHO and CHOS type of molecules, smaller molecules of higher aliphaticity and lower oxygen content and typical surfactants. A non-targeted mass spectrometric analysis of the samples showed that many of these molecules correspond to homologous series of oxo-, hydroxyl-, methoxy-, branched fatty acids and mono-, di- and tricarboxylic acids as well as monoterpenes and sugars. These surface active biomolecules were preferentially transferred from surface water into the atmosphere via bubble bursting processes to form a significant fraction of primary organic aerosols. This way of production of sea spray leaves a specific biological signature of the surface water in the corresponding lower atmosphere that can be transported laterally in the context of global cycling.
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Holzinger, R., J. Williams, F. Herrmann, J. Lelieveld, N. M. Donahue i T. Röckmann. "Aerosol analysis using a Thermal-Desorption Proton-Transfer-Reaction Mass Spectrometer (TD-PTR-MS): a new approach to study processing of organic aerosols". Atmospheric Chemistry and Physics 10, nr 5 (3.03.2010): 2257–67. http://dx.doi.org/10.5194/acp-10-2257-2010.
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Abstract. We present a novel analytical approach to measure the chemical composition of organic aerosol. The new instrument combines proton-transfer-reaction mass-spectrometry (PTR-MS) with a collection-thermal-desorption aerosol sampling technique. For secondary organic aerosol produced from the reaction of ozone with isoprenoids in a laboratory reactor, the TD-PTR-MS instrument detected typically 80% of the mass that was measured with a scanning mobility particle sizer (SMPS). The first field deployment of the instrument was the EUCAARI-IOP campaign at the CESAR tall tower site in the Netherlands. For masses with low background values (~30% of all masses) the detection limit of aerosol compounds was below 0.2 ng/m3 which corresponds to a sampled compound mass of 35 pg. Comparison of thermograms from ambient samples and from chamber-derived secondary organic aerosol shows that, in general, organic compounds from ambient aerosol samples desorb at much higher temperatures than chamber samples. This suggests that chamber aerosol is not a good surrogate for ambient aerosol and therefore caution is advised when extrapolating results from chamber experiments to ambient conditions.
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Barreira, Luís Miguel Feijó, Yu Xue, Geoffroy Duporté, Jevgeni Parshintsev, Kari Hartonen, Matti Jussila, Markku Kulmala i Marja-Liisa Riekkola. "Potential of needle trap microextraction–portable gas chromatography–mass spectrometry for measurement of atmospheric volatile compounds". Atmospheric Measurement Techniques 9, nr 8 (9.08.2016): 3661–71. http://dx.doi.org/10.5194/amt-9-3661-2016.
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Abstract. Volatile organic compounds (VOCs) play a key role in atmospheric chemistry and physics. They participate in photochemical reactions in the atmosphere, which have direct implications on climate through, e.g. aerosol particle formation. Forests are important sources of VOCs, and the limited resources and infrastructures often found in many remote environments call for the development of portable devices. In this research, the potential of needle trap microextraction and portable gas chromatography–mass spectrometry for the study of VOCs at forest site was evaluated. Measurements were performed in summer and autumn 2014 at the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR II) in Hyytiälä, Finland. During the first part of the campaign (summer) the applicability of the developed method was tested for the determination of monoterpenes, pinonaldehyde, aldehydes, amines and anthropogenic compounds. The temporal variation of aerosol precursors was determined, and evaluated against temperature and aerosol number concentration data. The most abundant monoterpenes, pinonaldehyde and aldehydes were successfully measured, their relative amounts being lower during days when particle number concentration was higher. Ethylbenzene, p- and m-xylene were also found when wind direction was from cities with substantial anthropogenic activity. An accumulation of VOCs in the snow cover was observed in the autumn campaign. Results demonstrated the successful applicability of needle trap microextraction and portable gas chromatography–mass spectrometry for the rapid in situ determination of organic gaseous compounds in the atmosphere.
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Kourtchev, Ivan, Ricardo H. M. Godoi, Sarah Connors, James G. Levine, Alex T. Archibald, Ana F. L. Godoi, Sarah L. Paralovo i in. "Molecular composition of organic aerosols in central Amazonia: an ultra-high-resolution mass spectrometry study". Atmospheric Chemistry and Physics 16, nr 18 (23.09.2016): 11899–913. http://dx.doi.org/10.5194/acp-16-11899-2016.
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Abstract. The Amazon Basin plays key role in atmospheric chemistry, biodiversity and climate change. In this study we applied nanoelectrospray (nanoESI) ultra-high-resolution mass spectrometry (UHRMS) for the analysis of the organic fraction of PM2.5 aerosol samples collected during dry and wet seasons at a site in central Amazonia receiving background air masses, biomass burning and urban pollution. Comprehensive mass spectral data evaluation methods (e.g. Kendrick mass defect, Van Krevelen diagrams, carbon oxidation state and aromaticity equivalent) were used to identify compound classes and mass distributions of the detected species. Nitrogen- and/or sulfur-containing organic species contributed up to 60 % of the total identified number of formulae. A large number of molecular formulae in organic aerosol (OA) were attributed to later-generation nitrogen- and sulfur-containing oxidation products, suggesting that OA composition is affected by biomass burning and other, potentially anthropogenic, sources. Isoprene-derived organosulfate (IEPOX-OS) was found to be the most dominant ion in most of the analysed samples and strongly followed the concentration trends of the gas-phase anthropogenic tracers confirming its mixed anthropogenic–biogenic origin. The presence of oxidised aromatic and nitro-aromatic compounds in the samples suggested a strong influence from biomass burning especially during the dry period. Aerosol samples from the dry period and under enhanced biomass burning conditions contained a large number of molecules with high carbon oxidation state and an increased number of aromatic compounds compared to that from the wet period. The results of this work demonstrate that the studied site is influenced not only by biogenic emissions from the forest but also by biomass burning and potentially other anthropogenic emissions from the neighbouring urban environments.
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Murschell, Trey, i Delphine K. Farmer. "Real-Time Measurement of Herbicides in the Atmosphere: A Case Study of MCPA and 2,4-D during Field Application". Toxics 7, nr 3 (6.08.2019): 40. http://dx.doi.org/10.3390/toxics7030040.
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Atmospheric sources of herbicides enable short- and long-range transport of these compounds to off-target areas but the concentrations and mechanisms are poorly understood due, in part, to the challenge of detecting these compounds in the atmosphere. We present chemical ionization time-of-flight mass spectrometry as a sensitive, real-time technique to detect chlorinated phenoxy acid herbicides in the atmosphere, using measurements during and after application over a field at Colorado State University as a case study. Gas-phase 2,4-dichlorophenoxyacetic acid (2,4-D) mixing ratios were greatest during application (up to 20 pptv), consistent with rapid volatilization from spray droplets. In contrast, atmospheric concentrations of 2-methyl-4-chlorophenoxyacetic acid (MCPA) increased for several hours after the initial application, indicative of a slower source than 2,4-D. The maximum observed gas-phase MCPA was 60 pptv, consistent with a post-application volatilization source to the atmosphere. Exposure to applied pesticides in the gas-phase can thus occur both during and at least several hours after application. Spray droplet volatilization and direct volatilization from surfaces may both contribute pesticides to the atmosphere, enabling pesticide transport to off-target and remote regions.
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Lyu, Ruihe, Zongbo Shi, Mohammed Salim Alam, Xuefang Wu, Di Liu, Tuan V. Vu, Christopher Stark, Pingqing Fu, Yinchang Feng i Roy M. Harrison. "Insight into the composition of organic compounds ( ≥ C<sub>6</sub>) in PM<sub>2.5</sub> in wintertime in Beijing, China". Atmospheric Chemistry and Physics 19, nr 16 (29.08.2019): 10865–81. http://dx.doi.org/10.5194/acp-19-10865-2019.
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Abstract. Organic matter is a major component of PM2.5 in megacities. In order to understand the detailed characteristics of organic compounds (≥ C6) at a molecular level on non-haze and haze days, we determined more than 300 organic compounds in the PM2.5 from an urban area of Beijing collected in November–December 2016 using two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-ToF-MS). The identified organic compounds have been classified into groups, and quantitative methods were used to calculate their concentrations. Primary emission sources make significant contributions to the atmospheric organic compounds, and six groups (including n-alkanes, polycyclic aromatic hydrocarbons – PAHs, levoglucosan, branched alkanes, n-alkenes and alkyl-benzenes) account for 66 % of total identified organic compound mass. In addition, PAHs and oxygenated PAHs (O-PAHs) were abundant amongst the atmospheric organic compounds on both haze and non-haze days. The most abundant hydrocarbon groups were observed with a carbon atom range of C19–C28. In addition, the total concentration of unidentified compounds present in the chromatogram was estimated in the present study. The total identified compounds account for approximately 47 % of total organic compounds (≥ C6) in the chromatogram on both the non-haze and haze days. The total mass concentrations of organic compounds (≥ C6) in the chromatogram were 4.0 and 7.4 µg m−3 on the non-haze and haze days, respectively, accounting for 26.4 % and 18.5 % of organic matter, respectively, on those days estimated from the total organic carbon concentration. Ratios of individual compound concentrations between haze and non-haze days do not give a clear indication of the degree of oxidation, but the overall distribution of organic compounds in the chromatogram provides strong evidence that the organic aerosol is less GC volatile and hence more highly oxidized on haze days.
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Sierau, B., R. Y. W. Chang, C. Leck, J. Paatero i U. Lohmann. "Single-particle characterization of the high-Arctic summertime aerosol". Atmospheric Chemistry and Physics 14, nr 14 (18.07.2014): 7409–30. http://dx.doi.org/10.5194/acp-14-7409-2014.
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Abstract. Single-particle mass-spectrometric measurements were carried out in the high Arctic north of 80° during summer 2008. The campaign took place onboard the icebreaker Oden and was part of the Arctic Summer Cloud Ocean Study (ASCOS). The instrument deployed was an aerosol time-of-flight mass spectrometer (ATOFMS) that provides information on the chemical composition of individual particles and their mixing state in real time. Aerosols were sampled in the marine boundary layer at stations in the open ocean, in the marginal ice zone, and in the pack ice region. The largest fraction of particles detected for subsequent analysis in the size range of the ATOFMS between approximately 200 and 3000 nm in diameter showed mass-spectrometric patterns, indicating an internal mixing state and a biomass burning and/or biofuel source. The majority of these particles were connected to an air mass layer of elevated particle concentration mixed into the surface mixed layer from the upper part of the marine boundary layer. The second largest fraction was represented by sea salt particles. The chemical analysis of the over-ice sea salt aerosol revealed tracer compounds that reflect chemical aging of the particles during their long-range advection from the marginal ice zone, or open waters south thereof prior to detection at the ship. From our findings we conclude that long-range transport of particles is one source of aerosols in the high Arctic. To assess the importance of long-range particle sources for aerosol–cloud interactions over the inner Arctic in comparison to local and regional biogenic primary aerosol sources, the chemical composition of the detected particles was analyzed for indicators of marine biological origin. Only a minor fraction showed chemical signatures of potentially ocean-derived primary particles of that kind. However, a chemical bias in the ATOFMS's detection capabilities observed during ASCOS might suggest the presence of a particle type of unknown composition and source. In general, the study suffered from low counting statistics due to the overall small number of particles found in this pristine environment, the small sizes of the prevailing aerosol below the detection limit of the ATOFMS, and its low hit rate. To our knowledge, this study reports on the first in situ single-particle mass-spectrometric measurements in the marine boundary layer of the high-Arctic pack ice region.
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Salami, Ayobami, Jorma Heikkinen, Laura Tomppo, Marko Hyttinen, Timo Kekäläinen, Janne Jänis, Jouko Vepsäläinen i Reijo Lappalainen. "A Comparative Study of Pyrolysis Liquids by Slow Pyrolysis of Industrial Hemp Leaves, Hurds and Roots". Molecules 26, nr 11 (25.05.2021): 3167. http://dx.doi.org/10.3390/molecules26113167.
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This study assessed the pyrolysis liquids obtained by slow pyrolysis of industrial hemp leaves, hurds, and roots. The liquids recovered between a pyrolysis temperature of 275–350 °C, at two condensation temperatures 130 °C and 70 °C, were analyzed. Aqueous and bio-oil pyrolysis liquids were produced and analyzed by proton nuclear magnetic resonance (NMR), gas chromatography–mass spectrometry (GC-MS), and atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS). NMR revealed quantitative concentrations of the most abundant compounds in the aqueous fractions and compound groups in the oily fractions. In the aqueous fractions, the concentration range of acetic acid was 50–241 gL−1, methanol 2–30 gL−1, propanoic acid 5–20 gL−1, and 1-hydroxybutan-2-one 2 gL−1. GC-MS was used to compare the compositions of the volatile compounds and APPI FT-ICR MS was utilized to determine the most abundant higher molecular weight compounds. The different obtained pyrolysis liquids (aqueous and oily) had various volatile and nonvolatile compounds such as acetic acid, 2,6-dimethoxyphenol, 2-methoxyphenol, and cannabidiol. This study provides a detailed understanding of the chemical composition of pyrolysis liquids from different parts of the industrial hemp plant and assesses their possible economic potential.
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Hatch, Lindsay E., Robert J. Yokelson, Chelsea E. Stockwell, Patrick R. Veres, Isobel J. Simpson, Donald R. Blake, John J. Orlando i Kelley C. Barsanti. "Multi-instrument comparison and compilation of non-methane organic gas emissions from biomass burning and implications for smoke-derived secondary organic aerosol precursors". Atmospheric Chemistry and Physics 17, nr 2 (31.01.2017): 1471–89. http://dx.doi.org/10.5194/acp-17-1471-2017.
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Abstract. Multiple trace-gas instruments were deployed during the fourth Fire Lab at Missoula Experiment (FLAME-4), including the first application of proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOFMS) and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC-TOFMS) for laboratory biomass burning (BB) measurements. Open-path Fourier transform infrared spectroscopy (OP-FTIR) was also deployed, as well as whole-air sampling (WAS) with one-dimensional gas chromatography–mass spectrometry (GC-MS) analysis. This combination of instruments provided an unprecedented level of detection and chemical speciation. The chemical composition and emission factors (EFs) determined by these four analytical techniques were compared for four representative fuels. The results demonstrate that the instruments are highly complementary, with each covering some unique and important ranges of compositional space, thus demonstrating the need for multi-instrument approaches to adequately characterize BB smoke emissions. Emission factors for overlapping compounds generally compared within experimental uncertainty, despite some outliers, including monoterpenes. Data from all measurements were synthesized into a single EF database that includes over 500 non-methane organic gases (NMOGs) to provide a comprehensive picture of speciated, gaseous BB emissions. The identified compounds were assessed as a function of volatility; 6–11 % of the total NMOG EF was associated with intermediate-volatility organic compounds (IVOCs). These atmospherically relevant compounds historically have been unresolved in BB smoke measurements and thus are largely missing from emission inventories. Additionally, the identified compounds were screened for published secondary organic aerosol (SOA) yields. Of the total reactive carbon (defined as EF scaled by the OH rate constant and carbon number of each compound) in the BB emissions, 55–77 % was associated with compounds for which SOA yields are unknown or understudied. The best candidates for future smog chamber experiments were identified based on the relative abundance and ubiquity of the understudied compounds, and they included furfural, 2-methyl furan, 2-furan methanol, and 1,3-cyclopentadiene. Laboratory study of these compounds will facilitate future modeling efforts.
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Piel, Felix, Markus Müller, Tomas Mikoviny, Sally E. Pusede i Armin Wisthaler. "Airborne measurements of particulate organic matter by proton-transfer-reaction mass spectrometry (PTR-MS): a pilot study". Atmospheric Measurement Techniques 12, nr 11 (13.11.2019): 5947–58. http://dx.doi.org/10.5194/amt-12-5947-2019.
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Abstract. Herein we report on the first successful airborne deployment of the CHemical Analysis of AeRosol ONline (CHARON) particle inlet which allowed us to measure the chemical composition of atmospheric submicrometer particles in real time using a state-of-the-art proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) analyzer. The data were collected aboard the NASA DC-8 Airborne Science Laboratory on 26 June 2018 over California in the frame of NASA's Student Airborne Research Program (SARP). We show exemplary data collected when the airplane (i) shortly encountered a fresh (<1 h old) smoke plume that had emanated from the Lions Fire in the Sierra Nevada, (ii) intercepted a particle plume emitted from an amine gas treating unit of a petroleum refinery close to Bakersfield, (iii) carried out a spatial survey in the boundary layer over the San Joaquin Valley and (iv) performed a vertical profile measurement over the greater Bakersfield area. The most important finding from this pilot study is that the CHARON PTR-ToF-MS system measures fast enough to be deployed on a jet research aircraft. The data collected during 3 to 15 s long plume encounters demonstrate the feasibility of airborne point or small area emission measurements. Further improvements are, however, warranted to eliminate or reduce the observed signal tailing (1/e decay time between 6 and 20 s). The fast time response of the analyzer allowed us to generate highly spatially resolved maps (1–2 km in the horizontal, 100 m in the vertical) of atmospheric particle chemical constituents. The chemical information that was extracted from the recorded particle mass spectra includes (i) mass concentrations of ammonium, nitrate and total organics; (ii) mass concentrations of different classes of organic compounds (CH vs. CHO vs. CHN vs. CHNO compounds; monoaromatic vs. polyaromatic compounds); (iii) aerosol bulk average O:C‾ and H:C‾ ratios; (iv) mass concentrations of selected marker molecules (e.g., levoglucosan in particles emitted from a wildfire, an alkanolamine in particles emitted from a petroleum refinery) and (v) wildfire emission ratios (Δtotal organics/ΔCO = 0.054; Δlevoglucosan/ΔCO = 7.9×10-3; Δvanillic acid/ΔCO = 4.4×10-4 and Δretene/ΔCO = 1.9×10-4; all calculated as peak area ratios, in grams per gram). The capability of the CHARON PTR-ToF-MS instrument to chemically characterize submicrometer atmospheric particles in a quantitative manner, at the near-molecular level, and in real time brings a new and unprecedented measurement capability to the airborne atmospheric science community.
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Fitzgerald, Robert L., Jeffrey D. Rivera i David A. Herold. "Broad Spectrum Drug Identification Directly from Urine, Using Liquid Chromatography-Tandem Mass Spectrometry". Clinical Chemistry 45, nr 8 (1.08.1999): 1224–34. http://dx.doi.org/10.1093/clinchem/45.8.1224.
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Abstract Background: Currently the rate-limiting step for mass spectrometric analysis of drugs in biological samples is sample preparation. Many gas chromatography/mass spectrometry (GC/MS) methods are specific for a certain class of compounds, requiring extraction and/or derivatization before analysis. The purpose of this study was to develop a broad spectrum liquid chromatography/mass spectrometry (LC/MS) procedure that allowed for direct analysis of urine specimens with potential for quantitative analysis. Methods: We modified a commercially available column-switching instrument, the REMEDi HS from Bio-Rad Diagnostics, to make it compatible with atmospheric pressure ionization. The system we developed was based on electrospray ionization and used three LC columns to extract, purify, and separate drugs directly from urine specimens. Drugs and metabolites were tentatively identified on the basis of retention times and (M+H)+ ions. Tandem mass spectrometry (MS/MS) was used to confirm the qualitative identification of suspected drugs, using data-dependent acquisition. For quantitative analysis, the cocaine metabolite benzoylecgonine was analyzed using isotope dilution and selected reaction monitoring. Results: Seventeen basic drugs from a variety of classes of compounds were identified directly from urine without the need for prior sample extraction, using LC and MS/MS. Quantitative analysis was demonstrated for benzoylecgonine. When benzoylecgonine-d3 was used as the internal standard, the method was linear from 30 to 10 000 μg/L (range tested). At these concentrations, the within-run accuracy was ± 10% of the target concentration, with CVs <10%. Analytical results by LC/MS/MS compared favorably with GC/MS values for 50 benzoylecgonine-containing specimens and for 25 negative specimens. Conclusions: The ability to directly analyze urine for a wide variety of drug classes, combined with the sensitivity and specificity of LC/MS/MS makes this technique attractive for many clinical, forensic, and biotechnology applications.
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Cheng, Bing-Ming, Eh Piew Chew, Wen-Ching Hung, Jürg Eberhard i Yuan-Pern Lee. "Photoionization studies of sulfur radicals and products of their reactions". Journal of Synchrotron Radiation 5, nr 3 (1.05.1998): 1041–43. http://dx.doi.org/10.1107/s0909049597016075.
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A discharge flow–photoionization mass spectrometric system coupled to a synchrotron is employed to study intermediates and products of sulfur radical reactions related to atmospheric chemistry. Sulfur radicals are generated from reactions of oxygen or chlorine atoms with sulfur compounds in a flow tube. The gaseous reaction products are sampled into the ionization region via a three-stage differential pumping scheme. Photoionization spectra and ionization energies are measured by dispersing synchrotron radiation to ionize the samples. Using this technique, photoionization spectra and ionization energies of HSO, CH3SO, C2H5SO, HSCl, and some secondary reaction products, SSCl, HSSCl, HSSSH, CH3SOH and CH3SS(O)CH3, were measured for the first time.
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Sengupta, Deep, Vera Samburova, Chiranjivi Bhattarai, Adam C. Watts, Hans Moosmüller i Andrey Y. Khlystov. "Polar semivolatile organic compounds in biomass-burning emissions and their chemical transformations during aging in an oxidation flow reactor". Atmospheric Chemistry and Physics 20, nr 13 (16.07.2020): 8227–50. http://dx.doi.org/10.5194/acp-20-8227-2020.
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Abstract. Semivolatile organic compounds (SVOCs) emitted from open biomass burning (BB) can contribute to chemical and physical properties of atmospheric aerosols and also may cause adverse health effects. The polar fraction of SVOCs is a prominent part of BB organic aerosols, and thus it is important to characterize the chemical composition and reactivity of this fraction. In this study, globally and regionally important representative fuels (Alaskan peat, Moscow peat, Pskov peat, eucalyptus, Malaysian peat, and Malaysian agricultural peat) were burned under controlled conditions using the combustion chamber facility at the Desert Research Institute (DRI). Gas- and particle-phase biomass-burning emissions were aged in an oxidation flow reactor (OFR) to mimic 5–7 d of atmospheric aging. Fresh and OFR-aged biomass-burning aerosols were collected on Teflon-impregnated glass fiber filters (TIGF) in tandem with XAD resin media for organic carbon speciation. The polar fraction extracted with dichloromethane and acetone was analyzed with gas chromatography mass spectrometry (GC-MS) for 84 polar organic compounds – including mono- and dicarboxylic acids, methoxylated phenols, aromatic acids, anhydrosugars, resin acids, and sterols. For all these compounds, fuel-based emission factors (EFs) were calculated for fresh and OFR-aged samples. The carbon mass of the quantified polar compounds was found to constitute 5 % to 7 % of the total organic compound mass. A high abundance of methoxyphenols (239 mg kg−1 for Pskov peat; 22.6 % of total GC-MS characterized mass) and resin acids (118 mg kg−1 for Alaskan peat; 14.5 % of total GC-MS characterized mass) was found in peat-burning emissions (smoldering combustion). The concentration of some organic compounds (e.g., tetracosanoic acid) with a molecular weight (MW) above 350 g mol−1 decreased after OFR aging, while abundances of low-MW compounds (e.g., hexanoic acid) increased. This indicated a significant extent of fragmentation reactions in the OFR. Methoxyphenols decreased after OFR aging, while a significant increase (3.7 to 8.6 times) in the abundance of dicarboxylic acids emission factors (EFs), especially maleic acid (10 to 60 times), was observed. EFs for fresh and ratios from fresh-to-aged BB samples reported in this study can be used to perform source apportionment and predict processes occurring during atmospheric transport.
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Stockwell, C. E., P. R. Veres, J. Williams i R. J. Yokelson. "Characterization of biomass burning emissions from cooking fires, peat, crop residue, and other fuels with high-resolution proton-transfer-reaction time-of-flight mass spectrometry". Atmospheric Chemistry and Physics 15, nr 2 (23.01.2015): 845–65. http://dx.doi.org/10.5194/acp-15-845-2015.
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Abstract. We deployed a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) to measure biomass-burning emissions from peat, crop residue, cooking fires, and many other fire types during the fourth Fire Lab at Missoula Experiment (FLAME-4) laboratory campaign. A combination of gas standard calibrations and composition sensitive, mass-dependent calibration curves was applied to quantify gas-phase non-methane organic compounds (NMOCs) observed in the complex mixture of fire emissions. We used several approaches to assign the best identities to most major "exact masses", including many high molecular mass species. Using these methods, approximately 80–96% of the total NMOC mass detected by the PTR-TOF-MS and Fourier transform infrared (FTIR) spectroscopy was positively or tentatively identified for major fuel types. We report data for many rarely measured or previously unmeasured emissions in several compound classes including aromatic hydrocarbons, phenolic compounds, and furans; many of these are suspected secondary organic aerosol precursors. A large set of new emission factors (EFs) for a range of globally significant biomass fuels is presented. Measurements show that oxygenated NMOCs accounted for the largest fraction of emissions of all compound classes. In a brief study of various traditional and advanced cooking methods, the EFs for these emissions groups were greatest for open three-stone cooking in comparison to their more advanced counterparts. Several little-studied nitrogen-containing organic compounds were detected from many fuel types, that together accounted for 0.1–8.7% of the fuel nitrogen, and some may play a role in new particle formation.
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Urban, Raphael D., Tillmann G. Fischer, Ales Charvat, Konstantin Wink, Benjamin Krafft, Stefan Ohla, Kirsten Zeitler, Bernd Abel i Detlev Belder. "On-chip mass spectrometric analysis in non-polar solvents by liquid beam infrared matrix-assisted laser dispersion/ionization". Analytical and Bioanalytical Chemistry 413, nr 6 (21.01.2021): 1561–70. http://dx.doi.org/10.1007/s00216-020-03115-4.
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AbstractBy the on-chip integration of a droplet generator in front of an emitter tip, droplets of non-polar solvents are generated in a free jet of an aqueous matrix. When an IR laser irradiates this free liquid jet consisting of water as the continuous phase and the non-polar solvent as the dispersed droplet phase, the solutes in the droplets are ionized. This ionization at atmospheric pressure enables the mass spectrometric analysis of non-polar compounds with the aid of a surrounding aqueous matrix that absorbs IR light. This works both for non-polar solvents such as n-heptane and for water non-miscible solvents like chloroform. In a proof of concept study, this approach is applied to monitor a photooxidation of N-phenyl-1,2,3,4-tetrahydroisoquinoline. Graphical abstract
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Thoma, Markus, Franziska Bachmeier, Felix Leonard Gottwald, Mario Simon i Alexander Lucas Vogel. "Mass spectrometry-based Aerosolomics: a new approach to resolve sources, composition, and partitioning of secondary organic aerosol". Atmospheric Measurement Techniques 15, nr 23 (12.12.2022): 7137–54. http://dx.doi.org/10.5194/amt-15-7137-2022.
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Abstract. Particulate matter (PM) largely consists of secondary organic aerosol (SOA) that is formed via oxidation of biogenic and anthropogenic volatile organic compounds (VOCs). Unambiguous identification of SOA molecules and their assignment to their precursor vapors are challenges that have so far only succeeded for a few SOA marker compounds, which are now well characterized and (partly) available as authentic standards. In this work, we resolve the complex composition of SOA by means of a top-down approach based on the newly created Aerosolomics database, which is fed by non-target analysis results of filter samples from oxidation flow reactor experiments. We investigated the oxidation products from the five biogenic VOCs α-pinene, β-pinene, limonene, 3-carene, and trans-caryophyllene and from the four anthropogenic VOCs toluene, o-xylene, 1,2,4-trimethylbenzene, and naphthalene. Using ultrahigh-performance liquid chromatography coupled to a high-resolution (Orbitrap) mass spectrometer, we determine the molecular formula of 596 chromatographically separated compounds based on exact mass and isotopic pattern. We utilize retention time and fragmentation mass spectra as a basis for unambiguous attribution of the oxidation products to their parent VOCs. Based on the molecular-resolved application of the database, we are able to assign roughly half of the total signal of oxygenated hydrocarbons in ambient suburban PM2.5 to one of the nine studied VOCs. The application of the database enabled us to interpret the appearance of diurnal compound clusters that are formed by different oxidation processes. Furthermore, by performing a hierarchical cluster analysis (HCA) on the same set of filter samples, we identified compound clusters that depend on sulfur dioxide mixing ratio and temperature. This study demonstrates how Aerosolomics tools (database and HCA) applied to PM filter samples can improve our understanding of SOA sources, their formation pathways, and temperature-driven partitioning of SOA compounds.
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Michoud, Vincent, Stéphane Sauvage, Thierry Léonardis, Isabelle Fronval, Alexandre Kukui, Nadine Locoge i Sébastien Dusanter. "Field measurements of methylglyoxal using proton transfer reaction time-of-flight mass spectrometry and comparison to the DNPH–HPLC–UV method". Atmospheric Measurement Techniques 11, nr 10 (18.10.2018): 5729–40. http://dx.doi.org/10.5194/amt-11-5729-2018.
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Abstract. Methylglyoxal (MGLY) is an important atmospheric α-dicarbonyl species for which photolysis acts as a significant source of peroxy radicals, contributing to the oxidizing capacity of the atmosphere and, as such, the formation of secondary pollutants such as organic aerosols and ozone. However, despite its importance, only a few techniques exhibit time resolutions and detection limits that are suitable for atmospheric measurements. This study presents the first field measurements of MGLY by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) performed during the ChArMEx SOP2 field campaign. This campaign took place at a Mediterranean site characterized by intense biogenic emissions and low levels of anthropogenic trace gases. Concomitant measurements of MGLY were performed using the 2,4-dinitrophenylhydrazine (DNPH) derivatization technique and high performance liquid chromatography (HPLC) with UV detection. PTR-ToF-MS and DNPH–HPLC measurements were compared to determine whether these techniques can perform reliable measurements of MGLY. Ambient time series revealed levels of MGLY ranging from 28 to 365 pptv, with a clear diurnal cycle due to elevated concentrations of primary biogenic species during the daytime, and its oxidation led to large production rates of MGLY. A scatter plot of the PTR-ToF-MS and DNPH–HPLC measurements indicates a reasonable correlation (R2=0.48) but a slope significantly lower than unity (0.58±0.05) and a significant intercept of 88.3±8.0 pptv. A careful investigation of the differences between the two techniques suggests that this disagreement is not due to spectrometric interferences from H3O+(H2O)3 or methyl ethyl ketone (or butanal) detected at m∕z 73.050 and m∕z 73.065, respectively, which are close to the MGLY m∕z of 73.029. The differences are more likely due to uncorrected sampling artifacts such as overestimated collection efficiency or loss of MGLY into the sampling line for the DNPH–HPLC technique or unknown isobaric interfering compounds such as acrylic acid and propanediol for the PTR-ToF-MS. Calculations of MGLY loss rates with respect to OH oxidation and direct photolysis indicate similar contributions for these two loss pathways.
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Kozikowski, Barbara A., Thomas M. Burt, Debra A. Tirey, Lisa E. Williams, Barbara R. Kuzmak, David T. Stanton, Kenneth L. Morand i Sandra L. Nelson. "The Effect of Freeze/Thaw Cycles on the Stability of Compounds in DMSO". Journal of Biomolecular Screening 8, nr 2 (kwiecień 2003): 210–15. http://dx.doi.org/10.1177/1087057103252618.
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A diverse set of 320 compounds from the Procter & Gamble Pharmaceuticals organic compound repository was prepared as 20-mM DMSO solutions and stored at 4°C under argon in pressurized canisters to simulate a low-humidity environment. The plates were subjected to 25 freeze/thaw cycles while being exposed to ambient atmospheric conditions after each thaw to simulate the time and manner by which compound plates are exposed to the atmosphere during typical liquid-handling and high-throughput screening processes. High-performance liquid chromatography–mass spectrometry with evaporative light-scattering detection was used to quantitate the amount of compound remaining after every 5th freeze/thaw cycle. Control plates were stored either at room temperature under argon or at 4°C under argon without freeze/thaw cycling and were evaluated at the midpoint and the endpoint of the study. The study was conducted over a short time period (i.e., 7 weeks) to minimize the effect of compound degradation over time due to the exposure of the compounds to DMSO.The results from this study will be used to determine the maximum number of freeze/thaw cycles that can be achieved while maintaining acceptable compound integrity.(Journal of Biomolecular Screening 2003:210-215)
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Röhler, Laura, Pernilla Bohlin-Nizzetto, Pawel Rostkowski, Roland Kallenborn i Martin Schlabach. "Non-target and suspect characterisation of organic contaminants in ambient air – Part 1: Combining a novel sample clean-up method with comprehensive two-dimensional gas chromatography". Atmospheric Chemistry and Physics 21, nr 3 (9.02.2021): 1697–716. http://dx.doi.org/10.5194/acp-21-1697-2021.
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Abstract. Long-term monitoring of regulated organic chemicals, such as legacy persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs), in ambient air provides valuable information about the compounds' environmental fate as well as temporal and spatial trends. This is the foundation to evaluate the effectiveness of national and international regulations for priority pollutants. Extracts of high-volume air samples, collected on glass fibre filters (GFF for particle phase) and polyurethane foam plugs (PUF for gaseous phase), for targeted analyses of legacy POPs are commonly cleaned by treatment with concentrated sulfuric acid, resulting in extracts clean from most interfering compounds and matrices that are suitable for multi-quantitative trace analysis. Such standardised methods, however, severely restrict the number of analytes for quantification and are not applicable when targeting new and emerging compounds as some may be less stable under acid treatment. Recently developed suspect and non-target screening analytical strategies (SUS and NTS, respectively) are shown to be effective evaluation tools aimed at identifying a high number of compounds of emerging concern. These strategies, combining highly sophisticated analytical technology with extensive data interpretation and statistics, are already widely accepted in environmental sciences for investigations of various environmental matrices, but their application to air samples is still very limited. In order to apply SUS and NTS for the identification of organic contaminants in air samples, an adapted and more wide-scope sample clean-up method is needed compared to the traditional method, which uses concentrated sulfuric acid. Analysis of raw air sample extracts without clean-up would generate extensive contamination of the analytical system, especially with PUF matrix-based compounds, and thus highly interfered mass spectra and detection limits which are unacceptable high for trace analysis in air samples. In this study, a novel wide-scope sample clean-up method for high-volume air samples has been developed and applied to real high-volume air samples, which facilitates simultaneous target, suspect and non-target analyses. The scope and efficiency of the method were quantitatively evaluated with organic compounds covering a wide range of polarities (logP 2–11), including legacy POPs, brominated flame retardants (BFRs), chlorinated pesticides and currently used pesticides (CUPs). In addition, data reduction and selection strategies for SUS and NTS were developed for comprehensive two-dimensional gas chromatography separation with low-resolution time-of-flight mass spectrometric detection (GC × GC-LRMS) data and applied to real high-volume air samples. Combination of the newly developed clean-up procedure and data treatment strategy enabled the prioritisation of over 600 compounds of interest in the particle phase (on GFF) and over 850 compounds in the gas phase (on PUF) out of over 25 000 chemical features detected in the raw dataset. Of these, 50 individual compounds were identified and confirmed with reference standards, 80 compounds were identified with a probable structure, and 774 compounds were assigned to various compound classes. In the dataset available here, 11 hitherto unknown halogenated compounds were detected. These unknown compounds were not yet listed in the available mass spectral libraries.
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Aljawhary, D., A. K. Y. Lee i J. P. D. Abbatt. "High-resolution chemical ionization mass spectrometry (ToF-CIMS): application to study SOA composition and processing". Atmospheric Measurement Techniques 6, nr 11 (26.11.2013): 3211–24. http://dx.doi.org/10.5194/amt-6-3211-2013.
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Abstract. This paper demonstrates the capabilities of chemical ionization mass spectrometry (CIMS) to study secondary organic aerosol (SOA) composition with a high-resolution (HR) time-of-flight mass analyzer (aerosol-ToF-CIMS). In particular, by studying aqueous oxidation of water-soluble organic compounds (WSOC) extracted from α-pinene ozonolysis SOA, we assess the capabilities of three common CIMS reagent ions: (a) protonated water clusters (H2O)nH+, (b) acetate CH3C(O)O− and (c) iodide water clusters I(H2O)n− to monitor SOA composition. Furthermore, we report the relative sensitivity of these reagent ions to a wide range of common organic aerosol constituents. We find that (H2O)nH+ is more selective to the detection of less oxidized species, so that the range of O / C and OSC (carbon oxidation state) in the SOA spectra is considerably lower than those measured using CH3C(O)O− and I(H2O)n−. Specifically, (H2O)nH+ ionizes organic compounds with OSC ≤ 1.3, whereas CH3C(O)O− and I(H2O)n− both ionize highly oxygenated organics with OSC up to 4 with I(H2O)n− being more selective towards multi-functional organic compounds. In the bulk O / C and H / C space (in a Van Krevelen plot), there is a remarkable agreement in both absolute magnitude and oxidation trajectory between ToF-CIMS data and those from a high-resolution aerosol mass spectrometer (HR-AMS). Despite not using a sensitivity-weighted response for the ToF-CIMS data, the CIMS approach appears to capture much of the chemical change occurring. As demonstrated by the calibration experiments with standards, this is likely because there is not a large variability in sensitivities from one highly oxygenated species to another, particularly for the CH3C(O)O− and I(H2O)n− reagent ions. Finally, the data illustrate the capability of aerosol-ToF-CIMS to monitor specific chemical change, including the fragmentation and functionalization reactions that occur during organic oxidation, and the oxidative conversion of dimeric SOA species into monomers. Overall, aerosol-ToF-CIMS is a valuable, selective complement to some common SOA characterization methods, such as AMS and spectroscopic techniques. Both laboratory and ambient SOA samples can be analyzed using the techniques illustrated in the paper.
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Kahnt, A., Y. Iinuma, A. Mutzel, O. Böge, M. Claeys i H. Herrmann. "Campholenic aldehyde ozonolysis: a mechanism leading to specific biogenic secondary organic aerosol constituents". Atmospheric Chemistry and Physics 14, nr 2 (22.01.2014): 719–36. http://dx.doi.org/10.5194/acp-14-719-2014.
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Abstract. In the present study, campholenic aldehyde ozonolysis was performed to investigate pathways leading to specific biogenic secondary organic aerosol (SOA) marker compounds. Campholenic aldehyde, a known α-pinene oxidation product, is suggested to be a key intermediate in the formation of terpenylic acid upon α-pinene ozonolysis. It was reacted with ozone in the presence and absence of an OH radical scavenger, leading to SOA formation with a yield of 0.75 and 0.8, respectively. The resulting oxidation products in the gas and particle phases were investigated employing a denuder/filter sampling combination. Gas-phase oxidation products bearing a carbonyl group, which were collected by the denuder, were derivatised by 2,4-dinitrophenylhydrazine (DNPH) followed by liquid chromatography/negative ion electrospray ionisation time-of-flight mass spectrometry analysis and were compared to the gas-phase compounds detected by online proton-transfer-reaction mass spectrometry. Particle-phase products were also analysed, directly or after DNPH derivatisation, to derive information about specific compounds leading to SOA formation. Among the detected compounds, the aldehydic precursor of terpenylic acid was identified and its presence was confirmed in ambient aerosol samples from the DNPH derivatisation, accurate mass data, and additional mass spectrometry (MS2 and MS3 fragmentation studies). Furthermore, the present investigation sheds light on a reaction pathway leading to the formation of terpenylic acid, involving α-pinene, α-pinene oxide, campholenic aldehyde, and terpenylic aldehyde. Additionally, the formation of diaterpenylic acid acetate could be connected to campholenic aldehyde oxidation. The present study also provides insights into the source of other highly functionalised oxidation products (e.g. m / z 201, C9H14O5 and m / z 215, C10H16O5), which have been observed in ambient aerosol samples and smog chamber-generated monoterpene SOA. The m / z 201 and 215 compounds were tentatively identified as a C9- and C10-carbonyl-dicarboxylic acid, respectively, based on reaction mechanisms of campholenic aldehyde and ozone, as well as detailed interpretation of mass spectral data, in conjunction with the formation of corresponding DNPH derivatives.
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Dunne, Erin, Ian E. Galbally, Min Cheng, Paul Selleck, Suzie B. Molloy i Sarah J. Lawson. "Comparison of VOC measurements made by PTR-MS, adsorbent tubes–GC-FID-MS and DNPH derivatization–HPLC during the Sydney Particle Study, 2012: a contribution to the assessment of uncertainty in routine atmospheric VOC measurements". Atmospheric Measurement Techniques 11, nr 1 (10.01.2018): 141–59. http://dx.doi.org/10.5194/amt-11-141-2018.
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Abstract. Understanding uncertainty is essential for utilizing atmospheric volatile organic compound (VOC) measurements in robust ways to develop atmospheric science. This study describes an inter-comparison of the VOC data, and the derived uncertainty estimates, measured with three independent techniques (PTR-MS, proton-transfer-reaction mass spectrometry; GC-FID-MS, gas chromatography with flame-ionization and mass spectrometric detection; and DNPH–HPLC, 2,4-dinitrophenylhydrazine derivatization followed by analysis by high-performance liquid chromatography) during routine monitoring as part of the Sydney Particle Study (SPS) campaign in 2012. Benzene, toluene, C8 aromatics, isoprene, formaldehyde and acetaldehyde were selected for the comparison, based on objective selection criteria from the available data. Bottom-up uncertainty analyses were undertaken for each compound and each measurement system. Top-down uncertainties were quantified via the inter-comparisons. In all seven comparisons, the correlations between independent measurement techniques were high with R2 values with a median of 0.92 (range 0.75–0.98) and small root mean square of the deviations (RMSD) of the observations from the regression line with a median of 0.11 (range 0.04–0.23 ppbv). These results give a high degree of confidence that for each comparison the response of the two independent techniques is dominated by the same constituents. The slope and intercept as determined by reduced major axis (RMA) regression gives a different story. The slopes varied considerably with a median of 1.25 and a range of 1.16–2.01. The intercepts varied with a median of 0.04 and a range of −0.03 to 0.31 ppbv. An ideal comparison would give a slope of 1.00 and an intercept of 0. Some sources of uncertainty that are poorly quantified by the bottom-up uncertainty analysis method were identified, including: contributions of non-target compounds to the measurement of the target compound for benzene, toluene and isoprene by PTR-MS as well as the under-reporting of formaldehyde, acetaldehyde and acetone by the DNPH technique. As well as these, this study has identified a specific interference of liquid water with acetone measurements by the DNPH technique. These relationships reported for Sydney 2012 were incorporated into a larger analysis with 61 similar published inter-comparison studies for the same compounds. Overall, for the light aromatics, isoprene and the C1–C3 carbonyls, the uncertainty in a set of measurements varies by a factor of between 1.5 and 2. These uncertainties (∼50 %) are significantly higher than uncertainties estimated using standard propagation of error methods, which in this case were ∼22 % or less, and are the result of the presence of poorly understood or neglected processes that affect the measurement and its uncertainty. The uncertainties in VOC measurements identified here should be considered when assessing the reliability of VOC measurements from routine monitoring with individual, stand-alone instruments; when utilizing VOC data to constrain and inform air quality and climate models; when using VOC observations for human exposure studies; and for comparison with satellite retrievals.
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Grace, Daisy N., Melissa B. Sebold i Melissa M. Galloway. "Separation and detection of aqueous atmospheric aerosol mimics using supercritical fluid chromatography–mass spectrometry". Atmospheric Measurement Techniques 12, nr 7 (12.07.2019): 3841–51. http://dx.doi.org/10.5194/amt-12-3841-2019.
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Abstract. Atmospheric particles contain thousands of compounds with many different functional groups and a wide range of polarities. Typical separation methods for aqueous atmospheric systems include reverse-phase liquid chromatography or derivatization of analytes of interest followed by gas chromatography. This study introduces supercritical fluid chromatography–mass spectrometry as a separation method for the methylglyoxal–ammonium sulfate reaction mixture (a proxy for aqueous atmospheric aerosol mimics). Several column compositions, mobile-phase modifiers, and column temperatures were examined to determine their effect on separation and optimum conditions for separation. Polar columns such as the Viridis UPC2™ BEH column combined with a mobile-phase gradient of carbon dioxide and methanol provided the best separation of compounds in the mixture and, when coupled to an electrospray ionization tandem mass spectrometer, allowed for detection of several new masses in the methylglyoxal–ammonium sulfate reaction mixture as well as the possible identification of several isomers. This analysis method can be extended to other aqueous aerosol mimics, including the mixtures of other aldehydes or organic acids with ammonium or small amines.
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Müller, M., L. H. Mielke, M. Breitenlechner, S. A. McLuckey, P. B. Shepson, A. Wisthaler i A. Hansel. "MS/MS studies for the selective detection of isomeric biogenic VOCs using a Townsend Discharge Triple Quadrupole Tandem MS and a PTR-Linear Ion Trap MS". Atmospheric Measurement Techniques Discussions 2, nr 4 (4.08.2009): 1837–61. http://dx.doi.org/10.5194/amtd-2-1837-2009.
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Abstract. We performed MS/MS investigations of biogenic volatile organic compounds (BVOC) using a triple quadrupole tandem mass spectrometer (QqQ-MS) equipped with a Townsend Discharge ion source and a Proton Transfer Reaction Linear Ion Trap (PTR-LIT) mass spectrometer. Both instruments use H2O chemical ionization to produce protonated molecular ions. Here we report a study of the application of these instruments to determine methyl vinyl ketone (MVK) and methacrolein (MACR) and a series of monoterpenes (α-pinene, β-pinene, 3-carene, limonene, myrcene, ocimene) and sesquiterpenes (humulene and farnesene). Both instruments achieved sub-ppb detection limits in the single MS mode and in the MS/MS mode for differentiating MVK and MACR. Collision induced dissociation (CID) of protonated monoterpenes and sesquiterpenes was studied under the high-energy, single-to-few collision conditions of the QqQ-MS instrument and under the low-energy, multiple collision conditions of the PTR-LIT. Differences and similarities in the breakdown curves obtained are discussed. In addition, we performed MS4 of protonated limonene to illustrate the analytical power of the PTR-LIT. In spite of the progress we have made, the selective on-line mass-spectrometric detection of individual monoterpenes or sesquiterpenes in complex mixtures currently does not yet seem to be possible.
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Müller, M., L. H. Mielke, M. Breitenlechner, S. A. McLuckey, P. B. Shepson, A. Wisthaler i A. Hansel. "MS/MS studies for the selective detection of isomeric biogenic VOCs using a Townsend Discharge Triple Quadrupole Tandem MS and a PTR-Linear Ion Trap MS". Atmospheric Measurement Techniques 2, nr 2 (12.11.2009): 703–12. http://dx.doi.org/10.5194/amt-2-703-2009.
Pełny tekst źródłaStreszczenie:
Abstract. We performed MS/MS investigations of biogenic volatile organic compounds (BVOC) using a triple quadrupole tandem mass spectrometer (QqQ-MS) equipped with a Townsend Discharge ion source and a Proton Transfer Reaction Linear Ion Trap (PTR-LIT) mass spectrometer. Both instruments use H2O chemical ionization to produce protonated molecules. Here we report a study of the application of these instruments to determine methyl vinyl ketone (MVK) and methacrolein (MACR) and a series of monoterpenes (α-pinene, β-pinene, 3-carene, limonene, myrcene, ocimene) and sesquiterpenes (humulene and farnesene). Both instruments achieved sub-ppb detection limits in the single MS mode and in the MS/MS mode for differentiating MVK and MACR. Collision induced dissociation (CID) of protonated monoterpenes and sesquiterpenes was studied under the relatively high-energy, single-to-few collision conditions of the QqQ-MS instrument and under the low-energy, multiple collision conditions of the PTR-LIT. Differences and similarities in the breakdown curves obtained are discussed. In addition, we performed MS4 of protonated limonene to illustrate the analytical power of the PTR-LIT. In spite of the progress we have made, the selective on-line mass-spectrometric detection of individual monoterpenes or sesquiterpenes in complex mixtures currently does not yet seem to be possible.
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Wang, Kai, Ru-Jin Huang, Martin Brüggemann, Yun Zhang, Lu Yang, Haiyan Ni, Jie Guo i in. "Urban organic aerosol composition in eastern China differs from north to south: molecular insight from a liquid chromatography–mass spectrometry (Orbitrap) study". Atmospheric Chemistry and Physics 21, nr 11 (15.06.2021): 9089–104. http://dx.doi.org/10.5194/acp-21-9089-2021.
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Abstract. Air pollution by particulate matter in China affects human health, the ecosystem and the climate. However, the chemical composition of particulate aerosol, especially of the organic fraction, is still not well understood. In this study, particulate aerosol samples with a diameter of ≤2.5 µm (PM2.5) were collected in January 2014 in three cities located in northeast, east and southeast China, namely Changchun, Shanghai and Guangzhou. Organic aerosol (OA) in the PM2.5 samples was analyzed by an ultrahigh-performance liquid chromatograph (UHPLC) coupled to a high-resolution Orbitrap mass spectrometer in both negative mode (ESI-) and positive mode electrospray ionization (ESI+). After non-target screening including the assignment of molecular formulas, the compounds were classified into five groups based on their elemental composition, i.e., CHO, CHON, CHN, CHOS and CHONS. The CHO, CHON and CHN groups present the dominant signal abundances of 81 %–99.7 % in the mass spectra and the majority of these compounds were assigned to mono- and polyaromatics, suggesting that anthropogenic emissions are a major source of urban OA in all three cities. However, the chemical characteristics of these compounds varied between the different cities. The degree of aromaticity and the number of polyaromatic compounds were substantially higher in samples from Changchun, which could be attributed to the large emissions from residential heating (i.e., coal combustion) during wintertime in northeast China. Moreover, the ESI- analysis showed higher H/C and O/C ratios for organic compounds in Shanghai and Guangzhou compared to samples from Changchun, indicating that OA undergoes more intense photochemical oxidation processes in lower-latitude regions of China and/or is affected to a larger degree by biogenic sources. The majority of sulfur-containing compounds (CHOS and CHONS) in all cities were assigned to aliphatic compounds with low degrees of unsaturation and aromaticity. Here again, samples from Shanghai and Guangzhou show a greater chemical similarity but differ largely from those from Changchun. It should be noted that the conclusions drawn in this study are mainly based on comparison of molecular formulas weighted by peak abundance and thus are associated with inherent uncertainties due to different ionization efficiencies for different organic species.
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Laube, J. C., A. Engel, H. Bönisch, T. Möbius, D. R. Worton, W. T. Sturges, K. Grunow i U. Schmidt. "Contribution of very short-lived organic substances to stratospheric chlorine and bromine in the tropics – a case study". Atmospheric Chemistry and Physics 8, nr 23 (11.12.2008): 7325–34. http://dx.doi.org/10.5194/acp-8-7325-2008.
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Abstract. The total stratospheric organic chlorine and bromine burden was derived from balloon-borne measurements in the tropics (Teresina, Brazil, 5°04´ S, 42°52´ W) in 2005. Whole air samples were collected cryogenically at altitudes between 15 and 34 km. For the first time, we report measurements of a set of 28 chlorinated and brominated substances in the tropical upper troposphere and stratosphere including ten substances with an atmospheric lifetime of less than half a year. The substances were quantified using pre-concentration techniques followed by Gas Chromatography with Mass Spectrometric detection. In the tropical tropopause layer at altitudes between 15 and 17 km we found 1.1–1.4% of the chlorine and 6–8% of the bromine to be present in the form of very short-lived organic compounds. By combining the data with tropospheric reference data and age of air observations the abundances of inorganic chlorine and bromine (Cly and Bry) were derived. At an altitude of 34 km we calculated 3062 ppt of Cly and 17.5 ppt of Bry from the decomposition of both long- and short-lived organic source gases. Furthermore we present indications for the presence of additional organic brominated substances in the tropical upper troposphere and stratosphere.
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Äijälä, Mikko, Kaspar R. Daellenbach, Francesco Canonaco, Liine Heikkinen, Heikki Junninen, Tuukka Petäjä, Markku Kulmala, André S. H. Prévôt i Mikael Ehn. "Constructing a data-driven receptor model for organic and inorganic aerosol – a synthesis analysis of eight mass spectrometric data sets from a boreal forest site". Atmospheric Chemistry and Physics 19, nr 6 (21.03.2019): 3645–72. http://dx.doi.org/10.5194/acp-19-3645-2019.
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Abstract. The interactions between organic and inorganic aerosol chemical components are integral to understanding and modelling climate and health-relevant aerosol physicochemical properties, such as volatility, hygroscopicity, light scattering and toxicity. This study presents a synthesis analysis for eight data sets, of non-refractory aerosol composition, measured at a boreal forest site. The measurements, performed with an aerosol mass spectrometer, cover in total around 9 months over the course of 3 years. In our statistical analysis, we use the complete organic and inorganic unit-resolution mass spectra, as opposed to the more common approach of only including the organic fraction. The analysis is based on iterative, combined use of (1) data reduction, (2) classification and (3) scaling tools, producing a data-driven chemical mass balance type of model capable of describing site-specific aerosol composition. The receptor model we constructed was able to explain 83±8 % of variation in data, which increased to 96±3 % when signals from low signal-to-noise variables were not considered. The resulting interpretation of an extensive set of aerosol mass spectrometric data infers seven distinct aerosol chemical components for a rural boreal forest site: ammonium sulfate (35±7 % of mass), low and semi-volatile oxidised organic aerosols (27±8 % and 12±7 %), biomass burning organic aerosol (11±7 %), a nitrate-containing organic aerosol type (7±2 %), ammonium nitrate (5±2 %), and hydrocarbon-like organic aerosol (3±1 %). Some of the additionally observed, rare outlier aerosol types likely emerge due to surface ionisation effects and likely represent amine compounds from an unknown source and alkaline metals from emissions of a nearby district heating plant. Compared to traditional, ion-balance-based inorganics apportionment schemes for aerosol mass spectrometer data, our statistics-based method provides an improved, more robust approach, yielding readily useful information for the modelling of submicron atmospheric aerosols physical and chemical properties. The results also shed light on the division between organic and inorganic aerosol types and dynamics of salt formation in aerosol. Equally importantly, the combined methodology exemplifies an iterative analysis, using consequent analysis steps by a combination of statistical methods. Such an approach offers new ways to home in on physicochemically sensible solutions with minimal need for a priori information or analyst interference. We therefore suggest that similar statistics-based approaches offer significant potential for un- or semi-supervised machine-learning applications in future analyses of aerosol mass spectrometric data.
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Weloe, Marcel, i Thorsten Hoffmann. "Application of time-of-flight aerosol mass spectrometry for the real-time measurement of particle-phase organic peroxides: an online redox derivatization–aerosol mass spectrometer (ORD-AMS)". Atmospheric Measurement Techniques 13, nr 10 (28.10.2020): 5725–38. http://dx.doi.org/10.5194/amt-13-5725-2020.
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Abstract. Aerosol mass spectrometers (AMS) are frequently applied in atmospheric aerosol research in connection with climate, environmental or health-related projects. This is also true for the measurement of the organic fraction of particulate matter, still the least understood group of components contributing to atmospheric aerosols. While quantification of the organic and/or inorganic aerosol fractions is feasible, more detailed information about individual organic compounds or compound classes can usually not be provided by AMS measurements. In this study, we present a new method to detect organic peroxides in the particle phase in real-time using an AMS. Peroxides (ROOR') are of high interest to the atmospheric aerosol community due to their potentially high mass contribution to SOA, their important role in new particle formation and their function as “reactive oxygen species” in aerosol–health-related topics. To do so, supersaturated gaseous triphenylphosphine (TPP) was continuously mixed with the aerosol flow of interest in a condensation/reaction volume in front of the AMS inlet. The formed triphenylphosphine oxide (TPPO) from the peroxide–TPP reaction was then detected by an aerosol mass spectrometer (AMS), enabling the semiquantitative determination of peroxide with a time resolution of 2 min. The method was tested with freshly formed and aged biogenic VOC and ozone SOA as well as in a short proof-of-principle study with ambient aerosol.
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Jamur, J. M. S. "Optimization of Plasma-Assisted Desorption/Ionization-Mass Spectrometry for Analysis of Ibuprofen". Industrial laboratory. Diagnostics of materials 89, nr 7 (25.07.2023): 21–24. http://dx.doi.org/10.26896/1028-6861-2023-89-7-21-24.
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In medical practice, nonsteroidal anti-inflammatory drugs (NSAIDs) are often used to treat osteoarthritis and rheumatoid arthritis. Ibuprofen is a well-known NSAID, analgesic, and antipyretic medication. This chemical is an active ingredient of several oral medications that are offered in tablet, gel pellet, and syrup forms and has higher efficacy, tolerance, and side effect rates than other compounds, including pyrazolone derivatives. We present a unique plasma-assisted desorption/ionization mass spectrometry (PADI-MS) approach for improving pharmaceutically important solids using an ibuprofen tablet as a model solid sample. The goal of the study is to create an innovative mass spectrometric method that could be used for quick and accurate analysis in the development of pharmaceutically relevant compounds. Sniffer tubes were used to route sample ions into a single quadrupole MS, with each acquisition lasting for 1 minute. Without any prior preparation, samples of ibuprofen tablets were directly exposed to PADI plasma for one minute at an atmosphere pressure. The approach is rapid, easy to use, and needs little to no sample preparation. In this study, the settings were improved by optimization of several parameters, such as plasma power, plasma-to-sample distance, and inner/outer flows of helium carrier gas, which were found to be 8 W, 2 mm, and 284 mL/min, respectively. The PADI-MS method provides a real-time information about structural features on the compounds. Ibuprofen tablets were used as a paradigm for pharmaceutically significant materials and direct PADI-MS analysis without a preliminary sample -treatment appeared to be successful: according to PADI-MS data a medication can be examined after one minute of plasma exposure.
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Zhao, Y., A. G. Hallar i L. R. Mazzoleni. "Atmospheric organic matter in clouds: exact masses and molecular formula identification using ultrahigh-resolution FT-ICR mass spectrometry". Atmospheric Chemistry and Physics 13, nr 24 (18.12.2013): 12343–62. http://dx.doi.org/10.5194/acp-13-12343-2013.
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Abstract. Clouds alter the composition of atmospheric aerosol by acting as a medium for interactions between gas- and particulate-phase substances. To determine the cloud water atmospheric organic matter (AOM) composition and study the cloud processing of aerosols, two samples of supercooled clouds were collected at the Storm Peak Laboratory near Steamboat Springs, Colorado (3220 m a.s.l.). Approximately 3000 molecular formulas were assigned to ultrahigh-resolution mass spectra of the samples after using a reversed-phase extraction procedure to isolate the AOM components from the cloud water. Nitrogen-containing compounds (CHNO compounds), sulfur-containing compounds (CHOS and CHNOS compounds) and other oxygen-containing compounds (CHO compounds) with molecular weights up to 700 Da were observed. Average oxygen-to-carbon ratios of ∼0.6 indicate a slightly more oxidized composition than most water-soluble organic carbon identified in aerosol studies, which may result from aqueous oxidation in the clouds. The AOM composition indicates significant influences from biogenic secondary organic aerosol (SOA) and residential wood combustion. We observed 60% of the cloud water CHO molecular formulas to be identical to SOA samples of α-pinene, β-pinene, d-limonene, and β-caryophyllene ozonolysis. CHNO compounds had the highest number frequency and relative abundances and are associated with residential wood combustion and NOx oxidation. Multiple nitrogen atoms in the assigned molecular formulas for the nighttime cloud sample composite were observed, indicating the significance of nitrate radical reactions on the AOM composition. Several CHOS and CHNOS compounds with reduced sulfur (in addition to the commonly observed oxidized sulfur-containing compounds) were also observed; however further investigation is needed to determine the origin of the reduced sulfur-containing compounds. Overall, the molecular composition determined using ultrahigh-resolution Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry provides an unambiguous identification of the cloud water organic anion composition in the Rocky Mountain area that could help to improve the understanding of aqueous-phase processes.
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Pawlaczyk, Mateusz, Rafał Frański, Michał Cegłowski i Grzegorz Schroeder. "Mass Spectrometric Investigation of Organo-Functionalized Magnetic Nanoparticles Binding Properties toward Chalcones". Materials 14, nr 16 (20.08.2021): 4705. http://dx.doi.org/10.3390/ma14164705.
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Chalcones are naturally occurring compounds exhibiting multiple biological functions related to their structure. The investigation of complexes formed by chalcones, namely 2′,4′-dihydroxy-2-methoxychalcone (DH-2-MC) and 2′,4′-dihydroxy-3-methoxychalcone (DH-3-MC), with organo-functionalized Fe3O4 magnetic nanoparticles using mass spectrometric techniques is reported. The magnetic nanoparticles were obtained by the silanization of Fe3O4 particles with 3-aminopropyltrimethosysilane, which were subsequently reacted with 3-hydroxybenzaldehyde (3-HBA) or 2-pyridinecarboxaldehyde (2-PCA), resulting in the formation of Schiff base derivatives. The formation of their complexes with chalcones was studied using electrospray (ESI) and flowing atmosphere-pressure afterglow (FAPA) mass spectrometric (MS) ionization techniques. The functional nanoparticles which were synthesized using 3-hydroxybenzaldehyde displayed higher affinity towards examined chalcones than their counterparts obtained using 2-pyridinecarboxaldehyde, which has been proved by both ESI and FAPA techniques. For the examined chalcones, two calibration curves were obtained using the ESI-MS method, which allowed for the quantitative analysis of the performed adsorption processes. The presence of Cu(II) ions in the system significantly hindered the formation of material–chalcone complexes, which was proved by the ESI and FAPA techniques. These results indicate that both mass spectrometric techniques used in our study possess a large potential for the investigation of the binding properties of various functional nanoparticles.
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Li, Junling, Hong Li, Kun Li, Yan Chen, Hao Zhang, Xin Zhang, Zhenhai Wu i in. "Enhanced secondary organic aerosol formation from the photo-oxidation of mixed anthropogenic volatile organic compounds". Atmospheric Chemistry and Physics 21, nr 10 (21.05.2021): 7773–89. http://dx.doi.org/10.5194/acp-21-7773-2021.
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Abstract. Vehicular exhaust is one of the important contribution sources of secondary organic aerosol (SOA) in urban areas. Long-chain alkanes and aromatic hydrocarbons are included in gaseous organic pollutants of vehicle emissions, representative of diesel and gasoline vehicles respectively. In this work, the SOA production from individual anthropogenic volatile organic compounds (AVOCs) (n-dodecane, 1,3,5-trimethylbenzene) and mixed AVOCs (n-dodecane + 1,3,5-trimethylbenzene) was studied with a large-scale outdoor smog chamber. Results showed that the SOA formation from the mixed AVOCs was enhanced compared to the predicted SOA mass concentration based on the SOA yield of individual AVOCs. According to the results of mass spectrometry analysis with electrospray ionization time-of-flight mass spectrometry (ESI-ToF-MS), interaction occurred between intermediate products from the two precursors, which could be the main reason for the enhanced SOA production from the mixed AVOC reaction system. The study results could improve our understanding about the contribution of representative precursors from vehicular exhaust to the formation of SOA in urban areas. This study also indicates that further studies on SOA chemistry from the mixed VOC reaction system are needed, as the interactions between them and the effect on SOA formation can give us a further understanding of the SOA formed in the atmosphere.
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DeRieux, Wing-Sy Wong, Ying Li, Peng Lin, Julia Laskin, Alexander Laskin, Allan K. Bertram, Sergey A. Nizkorodov i Manabu Shiraiwa. "Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition". Atmospheric Chemistry and Physics 18, nr 9 (4.05.2018): 6331–51. http://dx.doi.org/10.5194/acp-18-6331-2018.
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Abstract. Secondary organic aerosol (SOA) accounts for a large fraction of submicron particles in the atmosphere. SOA can occur in amorphous solid or semi-solid phase states depending on chemical composition, relative humidity (RH), and temperature. The phase transition between amorphous solid and semi-solid states occurs at the glass transition temperature (Tg). We have recently developed a method to estimate Tg of pure compounds containing carbon, hydrogen, and oxygen atoms (CHO compounds) with molar mass less than 450 g mol−1 based on their molar mass and atomic O : C ratio. In this study, we refine and extend this method for CH and CHO compounds with molar mass up to ∼ 1100 g mol−1 using the number of carbon, hydrogen, and oxygen atoms. We predict viscosity from the Tg-scaled Arrhenius plot of fragility (viscosity vs. Tg∕T) as a function of the fragility parameter D. We compiled D values of organic compounds from the literature and found that D approaches a lower limit of ∼ 10 (±1.7) as the molar mass increases. We estimated the viscosity of α-pinene and isoprene SOA as a function of RH by accounting for the hygroscopic growth of SOA and applying the Gordon–Taylor mixing rule, reproducing previously published experimental measurements very well. Sensitivity studies were conducted to evaluate impacts of Tg, D, the hygroscopicity parameter (κ), and the Gordon–Taylor constant on viscosity predictions. The viscosity of toluene SOA was predicted using the elemental composition obtained by high-resolution mass spectrometry (HRMS), resulting in a good agreement with the measured viscosity. We also estimated the viscosity of biomass burning particles using the chemical composition measured by HRMS with two different ionization techniques: electrospray ionization (ESI) and atmospheric pressure photoionization (APPI). Due to differences in detected organic compounds and signal intensity, predicted viscosities at low RH based on ESI and APPI measurements differ by 2–5 orders of magnitude. Complementary measurements of viscosity and chemical composition are desired to further constrain RH-dependent viscosity in future studies.
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Gallimore, Peter J., Chiara Giorio, Brendan M. Mahon i Markus Kalberer. "Online molecular characterisation of organic aerosols in an atmospheric chamber using extractive electrospray ionisation mass spectrometry". Atmospheric Chemistry and Physics 17, nr 23 (6.12.2017): 14485–500. http://dx.doi.org/10.5194/acp-17-14485-2017.
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Abstract. The oxidation of biogenic volatile organic compounds (VOCs) represents a substantial source of secondary organic aerosol (SOA) in the atmosphere. In this study, we present online measurements of the molecular constituents formed in the gas and aerosol phases during α-pinene oxidation in the Cambridge Atmospheric Simulation Chamber (CASC). We focus on characterising the performance of extractive electrospray ionisation (EESI) mass spectrometry (MS) for particle analysis. A number of new aspects of EESI-MS performance are considered here. We show that relative quantification of organic analytes can be achieved in mixed organic–inorganic particles. A comprehensive assignment of mass spectra for α-pinene derived SOA in both positive and negative ion modes is obtained using an ultra-high-resolution mass spectrometer. We compare these online spectra to conventional offline ESI-MS spectra and find good agreement in terms of the compounds identified, without the need for complex sample work-up procedures. Under our experimental conditions, EESI-MS signals arise only from particle-phase analytes. High-time-resolution (7 min) EESI-MS spectra are compared with simulations from the near-explicit Master Chemical Mechanism (MCM) for a range of reaction conditions. We show that MS peak abundances scale with modelled concentrations for condensable products (pinonic acid, pinic acid, OH-pinonic acid). Relative quantification is achieved throughout SOA formation as the composition, size and mass (5–2400 µg m−3) of particles is evolving. This work provides a robust demonstration of the advantages of EESI-MS for chamber studies over offline ESI-MS (time resolution, relative quantification) and over hard online techniques (molecular information).
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Li, Zhijian, Sergey A. Nizkorodov, Hong Chen, Xiaohui Lu, Xin Yang i Jianmin Chen. "Nitrogen-containing secondary organic aerosol formation by acrolein reaction with ammonia/ammonium". Atmospheric Chemistry and Physics 19, nr 2 (1.02.2019): 1343–56. http://dx.doi.org/10.5194/acp-19-1343-2019.
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Abstract. Ammonia-driven carbonyl-to-imine conversion is an important formation pathway to the nitrogen-containing organic compounds (NOCs) in secondary organic aerosols (SOAs). Previous studies have mainly focused on the dicarbonyl compounds as the precursors of light-absorbing NOCs. In this work, we investigated whether acrolein could also act as an NOC precursor. Acrolein is the simplest α, β-unsaturated mono-carbonyl compound, and it is ubiquitous in the atmosphere. Experiments probing multiphase reactions of acrolein as well as bulk aqueous-phase experiments were carried out to study the reactivity of acrolein towards ammonia and ammonium ions. Molecular characterization of the products based on gas chromatography mass spectrometry, high-resolution mass spectrometry, surface-enhanced Raman spectrometry and ultraviolet/visible spectrophotometry was used to propose possible reaction mechanisms. We observed 3-methylpyridine (commonly known as 3-picoline) in the gas phase in Tedlar bags filled with gaseous acrolein and ammonia or ammonium aerosols. In the ammonium-containing aqueous phase, oligomeric compounds with formulas (C3H4O)m(C3H5N)n and pyridinium compounds like (C3H4O)2C6H8N+ were observed as the products. The pathway to 3-methylpyridine was proposed to be the intramolecular carbon–carbon addition of the hemiaminal, which resulted from sequential carbonyl-to-imine conversions of acrolein molecules. The 3-methylpyridine was formed in the aqueous phase, but some of the 3-methylpyridine could revolatilize to the gas phase, explaining the observation of gaseous 3-methylpyridine in the bags. The (C3H4O)2C6H8N+ was a carbonyl-to-hemiaminal product from acrolein dimer and 3-methylpyridine, while the oligomeric products of (C3H4O)m(C3H5N)n were polymers of acroleins and propylene imines formed via carbonyl-to-imine conversion and condensation reactions. The pH value effect on the liquid products was also studied in the bulk aqueous-phase experiments. While the oligomeric compounds were forming in both acidic and alkaline conditions, the pyridinium products favored moderately acidic conditions. Both the oligomeric products and the pyridinium salts are light-absorbing materials. This work suggests that acrolein may serve as a precursor of light-absorbing heterocyclic NOCs in SOA. Therefore, secondary reactions of α, β-unsaturated aldehydes with reduced nitrogen should be taken into account as a source of light-absorbing NOCs in SOA.
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Rodigast, M., A. Mutzel, Y. Iinuma, S. Haferkorn i H. Herrmann. "Characterisation and optimisation of a method for the detection and quantification of atmospherically relevant carbonyl compounds in aqueous medium". Atmospheric Measurement Techniques Discussions 8, nr 1 (23.01.2015): 857–76. http://dx.doi.org/10.5194/amtd-8-857-2015.
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Abstract. Carbonyl compounds are ubiquitous in the atmosphere and either emitted primarily from anthropogenic and biogenic sources or they are produced secondarily from the oxidation of volatile organic compounds (VOC). Despite a number of studies about the quantification of carbonyl compounds a comprehensive description of optimised methods is scarce for the quantification of atmospherically relevant carbonyl compounds. Thus a method was systematically characterised and improved to quantify carbonyl compounds. Quantification with the present method can be carried out for each carbonyl compound sampled in the aqueous phase regardless of their source. The method optimisation was conducted for seven atmospherically relevant carbonyl compounds including acrolein, benzaldehyde, glyoxal, methyl glyoxal, methacrolein, methyl vinyl ketone and 2,3-butanedione. O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was used as derivatisation reagent and the formed oximes were detected by gas chromatography/mass spectrometry (GC/MS). The main advantage of the improved method presented in this study is the low detection limit in the range of 0.01 and 0.17 μmol L−1 depending on carbonyl compounds. Furthermore best results were found for extraction with dichloromethane for 30 min followed by derivatisation with PFBHA for 24 h with 0.43 mg mL−1 PFBHA at a pH value of 3. The optimised method was evaluated in the present study by the OH radical initiated oxidation of 3-methylbutanone in the aqueous phase. Methyl glyoxal and 2,3-butanedione were found to be oxidation products in the samples with a yield of 2% for methyl glyoxal and 14% for 2,3-butanedione.