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Littérature scientifique sur le sujet « Mass Spectrometric Study - Atmospheric Compounds »

Auteur : Grafiati

Publié le 7 septembre 2023

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Articles de revues sur le sujet "Mass Spectrometric Study - Atmospheric Compounds"

Röhler, Laura, Martin Schlabach, Peter Haglund, Knut Breivik, Roland Kallenborn, and 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, no. 14 (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, et al. "Real-time detection of highly oxidized organosulfates and BSOA marker compounds during the F-BEACh 2014 field study." Atmospheric Chemistry and Physics 17, no. 2 (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&amp;bullet;) were observed, suggesting RO2&amp;bullet; to be involved in HOOS formation.

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Zogka, Antonia G., Manolis N. Romanias, and Frederic Thevenet. "Formaldehyde and glyoxal measurement deploying a selected ion flow tube mass spectrometer (SIFT-MS)." Atmospheric Measurement Techniques 15, no. 7 (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, et al. "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, and Markus Kalberer. "Seasonal differences of urban organic aerosol composition – an ultra-high resolution mass spectrometry study." Environmental Chemistry 9, no. 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, et al. "Online mass spectrometric aerosol measurements during the MINOS campaign (Crete, August 2001)." Atmospheric Chemistry and Physics 4, no. 1 (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, no. 1 (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=90&ordm;) 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, et al. "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, no. 3 (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, and 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, no. 6 (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, et al. "Evaluating the performance of five different chemical ionization techniques for detecting gaseous oxygenated organic species." Atmospheric Measurement Techniques 12, no. 4 (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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Thèses sur le sujet "Mass Spectrometric Study - Atmospheric Compounds"

Fischbeck, Garlich [Verfasser], and J. [Akademischer Betreuer] Orphal. "Mass-spectrometric in-situ measurements of atmospheric volatile organic compounds onboard passenger and research aircraft / Garlich Fischbeck ; Betreuer: J. Orphal." Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/1168325617/34.

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Le, Maître Johann. "Développement de la spectrométrie de masse à ultra- haute résolution associée à la spectrométrie de mobilité ionique pour la caractérisation de coupes pétrolières lourdes. structural analysis of heavy oil fractions afterr hydrodenitrogenation by high-resolution tandem mass spectrometry and ion mobility spectrometry Structural analysis of neutral nitrogen compounds refractory to the hydrodenitrogenation process of heavy oil fractions by high-resolution tandem mass spectrometry and ion mobility-mass spectrometry Chemical characterization of 15 biocrudes obtained from hydrothermal liquefaction of industrially cultivated wild micro algae Chemical characterization with different analytical techniques, a way to understand the process: Case of the paraffinic base oil production line Exploring complex mixtures by cyclic ion mobility high-resolution mass spectrometry – Application towards Petroleum. Simulation and modeling of Collision Cross Section for structural elucidation of heavy oil fraction by ion mobility-mass spectrometry: Using polyaromatic hydrocarbons compounds mixture as calibration standard Characterization of sulfoxides compounds in dimeric distribution of heavy oil fractions by positive-ion electrospray ionization FTICR mass spectrometry Structural analysis of Petroporphyrins from asphaltene by trapped ion mobility coupled with a Fourier transform ion cyclotron resonance mass spectrometer. Cyclic ion mobility spectrometry coupled to high-resolution time-of-flight mass spectrometry equipped with atmospheric solid analysis probe for the molecular characterization of combustion particulate matter. Structural study of analogues of Titan’s haze by trapped ion mobility coupled with a Fourier transform ion cyclotron mass spectrometer." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR051.

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L'évolution des réserves de pétrole implique l'utilisation en raffinerie de pétroles bruts non conventionnels, bien souvent plus lourds et donc difficiles à caractériser. Les produits pétroliers sont en effet des mélanges chimiques extrêmement complexes. La partie légère et volatile peut être analysée par chromatographie en phase gazeuse couplée à la spectrométrie de masse (GC/MS), permettant l'identification des composés par l'utilisation de mesures de masses précises et de modèles de fragmentation. Cependant ces techniques sont inadaptées à l'analyse des fractions lourdes. Dans la pratique, la caractérisation des mélanges les plus complexes implique l'utilisation de spectromètres de masse à ultra-haute résolution généralement par analyse directe sans séparation chromatographique. La technique de référence est aujourd’hui la spectrométrie de masse à transformée de Fourier par résonance cyclotronique des ions (FTICR). Grâce à une résolution supérieure à 106 et à une précision de mesure de masse inférieure à 0,1 ppm, cet instrument permet de séparer toutes les espèces présentes dans un produit pétrolier et d'attribuer à chaque valeur de m/z une composition élémentaire unique. Ceci permet d'obtenir très facilement des cartes moléculaires qui peuvent être présentées graphiquement en utilisant le diagramme de Kendrick, le diagramme de van Krevelen ou le nombre d'insaturations (DBE) en fonction du nombre de carbones. Ce travail de thèse a permis grâce à la caractérisation moléculaire de produits pétroliers (Vacuum Gas Oil, Pétroles Bruts, Matériel Interfacial, Asphaltènes et Bio-Oil…) d'aborder la complexité de leur traitement dans l’outil de raffinage. Des protocoles d'analyses des échantillons ont été développés, à l'aide de différentes sources d'ionisation à pression atmosphérique (ESI, APCI et APPI) ainsi que par désorption/ionisation laser (LDI) sur le spectromètre de masse FTICR 12T. Les informations sur le contenu isomérique des produits pétroliers ont ensuite été déterminées grâce à l'apport de la spectrométrie de mobilité ionique (IMS)<br>The evolution of oil reserves requires the use in refineries of unconventional crude oils, which are often heavier and therefore difficult to characterize. Petroleum products are in fact extremely complex chemical mixtures. The light and volatile part can be analysed by gas chromatography coupled with mass spectrometry (GC/MS), allowing the identification of compounds by using precise mass measurements and fragmentation models. However, these techniques are inappropriate for the analysis of heavy fractions. In practice, the characterization of the most complex mixtures involves the use of ultra-high-resolution mass spectrometers generally by direct analysis without chromatographic separation. The reference technique today is Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR). With a resolution of more than 106 and a mass measurement accuracy of less than 0.1 ppm, this instrument can separate all the species present in a petroleum product and assign a unique elemental composition to each m/z value. This makes it very easy to obtain molecular maps that can be presented graphically using the Kendrick diagram, the van Krevelen diagram or the number of unsaturations (DBE) as a function of the number of carbons. This thesis work has allowed thanks to the molecular characterization of petroleum products (Vacuum Gas Oil, Crude Oil, Interfacial Material, Asphaltenes and Bio-Oil...) addressing the complexity of their treatment in the refining tool. Protocols for sample analysis have been developed, using different sources of ionization at atmospheric pressure (ESI, APCI and APPI) as well as laser desorption/ionization (LDI) on the FTICR 12T mass spectrometer. Information on the isomeric content of petroleum products was then determined using ion mobility spectrometry (IMS)

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Fitzgerald, Mark. "The mass spectrometric and theoretical study of some cumulene oxides of potential interstellar significance : submitted for the degree of Doctor of Philosophy (Ph.D.) /." Title page, table of contents and abstract only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phf5531.pdf.

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Castada, Hardy Zingalaoa. "A FUNDAMENTAL AND APPLIED APPROACH TO SELECTED ION FLOW TUBE-MASS SPECTROMETRIC STUDY OF VOLATILE ORGANIC COMPOUNDS IN SWISS-TYPE CHEESES." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405986395.

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Fitzgerald, Mark. "The mass spectrometric and theoretical study of some cumulene oxides of potential interstellar significance." Thesis, 2004. http://hdl.handle.net/2440/69460.

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Focuses upon a number of oxygen-substituted cumulenes (cumulene oxides), including charged and neutral states of CCCCO, several isomers of C₄HO and C₄H₂O, and HCCCCCO and CCCCCHO.<br>Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2004

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Chapitres de livres sur le sujet "Mass Spectrometric Study - Atmospheric Compounds"

Lin, M. C. "Multiphoton Ionization/Mass Spectrometric Study of OMCVD Mechanisms Under Single Gas-Surface Collision Conditions." In Mechanisms of Reactions of Organometallic Compounds with Surfaces. Springer US, 1989. http://dx.doi.org/10.1007/978-1-4899-2522-0_22.

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Rivera, J., F. Ventura, J. Caixach, J. Romero, and D. Fraisse. "FAB Mass Spectrometric Applications to the Study of Non Volatile Organic Compounds in Water." In Organic Micropollutants in the Aquatic Environment. Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3356-2_36.

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Rudzinski, Walter E. "Chromatographic Separation and Atmospheric Pressure Ionization/Mass Spectrometric Analysis of Nitrogen, Sulfur and Oxygen Containing Compounds in Crude Oils." In Analytical Advances for Hydrocarbon Research. Springer US, 2003. http://dx.doi.org/10.1007/978-1-4419-9212-3_13.

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Fang, Jingjing, Kexian Li, Xinhong Xu, Xiaomeng Ren, and Lu Jiang. "Air Contaminants in an Underwater Vehicle Cabin During Navigation." In Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210345.

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The purpose of this study is to study the air contaminants in the cabins of underwater vehicle. The basic data help for the better research of the underwater vehicle cabin environment standard and the control strategy. Pretreatment and analysis method of volatile organic compounds was preconcentration combined with gas chromatography under the condition of liquid nitrogen and detected by chromatography-mass spectrometry. The pollution of particles, carbon monoxide and carbon dioxide during the underwater vehicle voyage were monitored by online monitoring instrument. Altogether 34 kinds of pollution components were detected, most of which were low in concentration. Some are low olfactory threshold or high toxic components, such as dimethyldisulfide, benzene, carbon disulfide, trichloromethane, and several reached to ppm level. The contamination of the particles was mainly fine particles and part cabins exceeded the national standard of indoor air quality. The highest concentration of carbon dioxide in accommodation space exceeded the permissible concentration of atmosphere composition aboard diesel underwater vehicle compartments. The increase submerged time made the environment in the cabins deteriorate. The concentration of trace contaminants may close to or beyond the relevant standards with the prolonged time. The volatile organic compounds, particles, carbon monoxide and carbon dioxide aggravated the air circumstance in the cabins. It should be determined the permissible concentration of air contaminants in underwater vehicle as soon as possible.

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Actes de conférences sur le sujet "Mass Spectrometric Study - Atmospheric Compounds"

Lupaescu, Ancuta-Veronica, Brindusa-Alina Petre, Monica Iavorschi, and Mircea Oroian. "ANALYSIS OF PROTEIN CONTENT AND EVALUATION OF ANTIOXIDANT ACTIVITY OF LINDEN AND HAWTHORN POLLEN." In 22nd SGEM International Multidisciplinary Scientific GeoConference 2022. STEF92 Technology, 2022. http://dx.doi.org/10.5593/sgem2022/6.1/s25.08.

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Harvested bee pollen has been used since ancient times for its healthy properties and nutritional value. In terms of composition, bee pollen contains a large number of different substances such as proteins, carbohydrates and lipids as well as phenolic organic compounds. The protein content is the second most abundant component, its levels (10 to 40%, w/w) depending on the type of plant. Recently, numerous studies have demonstrated the beneficial properties of pollen in promoting health and reducing the risk of developing certain illnesses. In addition, the anti-oxidative and anti-aging effects have provided beneficial support for the development of bee pollen in the field of cosmetics. In this study, the effect of sonication treatment on the protein content of linden and hawthorn pollen was evaluated. Quantitative information regarding the protein content of sonicated extracts was determined by Bradford method while the antioxidant capacity of protein extract was evaluated using the DPPH free radical method. Furthermore, one dimensional electrophoresis and mass spectrometric analysis was used to acquire a more detailed description of pollen protein content.

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Sperka, Jirí, Lenka Zajícková, Ondrej Jasek, et al. "Growth of Carbon Materials on Gold Substrate by Plasma Enhanced CVD." In 13th International Conference on Plasma Surface Engineering September 10 - 14, 2012, in Garmisch-Partenkirchen, Germany. Linköping University Electronic Press, 2013. http://dx.doi.org/10.3384/wcc2.395-398.

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Carbon is a versatile building element of many interesting materials that have already find practical applications in the form of thin films (diamond, DLC) or potential applications in the form of nanostructures (fullerenes, carbon nanotubes, graphene). For electronics or sensors, it is important to provide a very good contact to the functional structures. Gold is the best choice taking into account its inertness, i. e. oxidation resistance. From this point of view the investigation of the growth of carbon materials on gold is important. The carbon-gold interaction plays an important role in different fields of electronics such as atomic force microscope lithography, bioelectronics or semiconductor industry. Research in this field is developing rapidly e. g. the modification of interface structure and contact resistance between a CNT and gold electrode was recently modified by Joule melting and amorphous C-Au nanocomposite thin films were deposited by dc magnetron co-sputtering. Herein we report on the preparation and characterization of the carbon nanocomposites which were synthesized on gold substrate from methane precursor using low pressure thermal chemical vapor deposition technique and two different plasma-enhanced chemical vapor deposition (PECVD) methods. The former one PECVD proceeded in microwave reactor at low pressure and the latter one was carried out using non-thermal atmospheric pressure plasma jet (ntAPPJ). Presented approach is based on the deposition of carbon material on gold instead of the deposition of gold on carbon material which is more common. Surprisingly, we didnt find similar studies dealing with the synthesis of carbon nanocomposites using direct deposition from hydrocarbon precursor on the gold thin _lm. The surface morphology was studied by high resolution scanning electron microscopy (HRSEM). Depth-structure profile including the film thickness was observed using the focused ion beam ablation. Energy-dispersive X-ray spectroscopy (EDX), infrared reflection absorption spectroscopy (IRRAS) and laser desorption-ionization time of flight mass spectrometry (LDI-TOF MS) were used to study the chemical properties. Gold and carbon related clusters were observed by means of mass spectrometric study.

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Moeckli, M., and M. W. Sigrist. "Trace-Gas Monitoring with a Mobile CO2-Laser Photoacoustic System." In The European Conference on Lasers and Electro-Optics. Optica Publishing Group, 1996. http://dx.doi.org/10.1364/cleo_europe.1996.cwd3.

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Laser photoacoustic spectroscopy is a powerful tool for the monitoring of a large number of gaseous substances at concentration levels varying from the ppb to the percent level. We have developed a fully computer controlled mobile CO2 laser photoacoustic spectrometer which has been involved in several field studies [1,2]. Our system will be presented including some recent developments. Owing to the strong absorption, CO2 laser spectroscopy is particularly sensitive to ethene and ammonia, two trace gases that are important for the production of photochemical smog and of acid rain, respectively, and which are both emitted by road traffic and other sources. These compounds are difficult to detect with alternative methods, particularly if a good time resolution and high sensitivity are required. With the widespread introduction of catalytic convenes in cars, the local concentration of traffic-emitted ammonia could have increased substantially in the recent past. We present first results of a field study performed with our system during a five day period in summer 1995 at a freeway tunnel outlet near Zurich. Tunnel air was pumped continuously through the photoacoustic cell. In order to avoid any adverse effects during sampling which could influence the components to be monitored we used neither CO2 nor H2O scrubbers but preferred to analyse the PA spectra by taking these two substances into account in the fitting procedure for the spectral analysis. The measurements were done at atmospheric pressure and simultaneous monitoring of CO2, ethene and ammonia was achieved with a time resolution of 10 minutes by automatic tuning to the appropriate laser transitions. Detection thresholds of a few ppb were obtained for ethene and ammonia. Furthermore, the CO level was monitored independently by a conventional device. The derived concentration profiles could be correlated with the data from an automatic traffic counting system. Rather high gas concentrations were derived, particularly for ethene and ammonia in the range of up to 250 ppb and 400 ppb, respectively. Even at night the ammonia concentrations stayed well above the background level of a few ppb. Based on these data and the calculated air flow through the tunnel, emission factors (mass of an exhausted component per car and km) from road traffic for the four substances could be determined. To our knowledge it is the first time that ammonia emission factors have been derived in Switzerland. An extrapolation with our emission factor of 15 mg ammonia per km and car indicates that traffic contributes approximately 1 % to the total ammonia emission into the air in Switzerland. A similar percentage was estimated for Austria in 1990. Local relative contributions can be much higher and strongly depend on the vehicle composition of the traffic.

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