scholarly journals Elemental composition and clustering behaviour of α-pinene oxidation products for different oxidation conditions

2015 ◽  
Vol 15 (8) ◽  
pp. 4145-4159 ◽  
Author(s):  
A. P. Praplan ◽  
S. Schobesberger ◽  
F. Bianchi ◽  
M. P. Rissanen ◽  
M. Ehn ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Organic Compounds ◽  
Atmospheric Pressure ◽  
Molar Mass ◽  
Oxidation Products ◽  
Neutral Species ◽  
Mass Spectrometers ◽  
Comprehensive Picture ◽  
The Difference ◽  
Chemical Ionisation

Abstract. This study presents the difference between oxidised organic compounds formed by α-pinene oxidation under various conditions in the CLOUD environmental chamber: (1) pure ozonolysis (in the presence of hydrogen as hydroxyl radical (OH) scavenger) and (2) OH oxidation (initiated by nitrous acid (HONO) photolysis by ultraviolet light) in the absence of ozone. We discuss results from three Atmospheric Pressure interface Time-of-Flight (APi-TOF) mass spectrometers measuring simultaneously the composition of naturally charged as well as neutral species (via chemical ionisation with nitrate). Natural chemical ionisation takes place in the CLOUD chamber and organic oxidised compounds form clusters with nitrate, bisulfate, bisulfate/sulfuric acid clusters, ammonium, and dimethylaminium, or get protonated. The results from this study show that this process is selective for various oxidised organic compounds with low molar mass and ions, so that in order to obtain a comprehensive picture of the elemental composition of oxidation products and their clustering behaviour, several instruments must be used. We compare oxidation products containing 10 and 20 carbon atoms and show that highly oxidised organic compounds are formed in the early stages of the oxidation.

scholarly journals Elemental composition and clustering of α-pinene oxidation products for different oxidation conditions

2014 ◽  
Vol 14 (22) ◽  
pp. 30799-30833
Author(s):  
A. P. Praplan ◽  
S. Schobesberger ◽  
F. Bianchi ◽  
M. P. Rissanen ◽  
M. Ehn ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Elemental Composition ◽  
Organic Compounds ◽  
Atmospheric Pressure ◽  
Oxidation Products ◽  
Neutral Species ◽  
Mass Spectrometers ◽  
Comprehensive Picture ◽  
The Difference ◽  
Chemical Ionisation

Abstract. This study presents the difference between oxidised organic compounds formed by α-pinene ozonolysis and hydroxyl radical (OH) oxidation in the CLOUD environmental chamber. The results from three Atmospheric Pressure interface Time-Of-Flight (APi-TOF) mass spectrometers measuring simultaneously the composition of naturally charged, as well as neutral species (via chemical ionisation with nitrate) are discussed. Natural chemical ionisation takes place in the CLOUD chamber and organic oxidised compounds form clusters with nitrate, bisulphate, bisulphate/sulphuric acid clusters, ammonium, and dimethylaminium, or get protonated. This process is selective towards various oxidised organic compounds, so that in order to get a comprehensive picture of the elemental composition of oxidation products, several instruments must be used. A comparison between oxidation products containing 10 and 20 carbon atoms is presented. Oxidation products from ozonolysis showed a higher oxidation state than the ones from OH oxidation. Also, highly oxidised organic compounds are shown to be formed in the early stages of the oxidation, for low α-pinene levels.

scholarly journals Using advanced mass spectrometry techniques to fully characterize atmospheric organic carbon: current capabilities and remaining gaps

2017 ◽  
Vol 200 ◽  
pp. 579-598 ◽  
Author(s):  
G. Isaacman-VanWertz ◽  
P. Massoli ◽  
R. E. O’Brien ◽  
J. B. Nowak ◽  
M. R. Canagaratna ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Structural Information ◽  
Carbon Number ◽  
Chemical Properties ◽  
Oxidation Products ◽  
Particle Phase ◽  
Atmospheric Measurements ◽  
Mass Spectrometers ◽  
Phase Measurements ◽  
New Generation

Organic compounds in the atmosphere vary widely in their molecular composition and chemical properties, so no single instrument can reasonably measure the entire range of ambient compounds. Over the past decade, a new generation of in situ, field-deployable mass spectrometers has dramatically improved our ability to detect, identify, and quantify these organic compounds, but no systematic approach has been developed to assess the extent to which currently available tools capture the entire space of chemical identity and properties that is expected in the atmosphere. Reduced-parameter frameworks that have been developed to describe atmospheric mixtures are exploited here to characterize the range of chemical properties accessed by a suite of instruments. Multiple chemical spaces (e.g. oxidation state of carbon vs. volatility, and oxygen number vs. carbon number) were populated with ions measured by several mass spectrometers, with gas- and particle-phase α-pinene oxidation products serving as the test mixture of organic compounds. Few gaps are observed in the coverage of the parameter spaces by the instruments employed in this work, though the full extent to which comprehensive measurement was achieved is difficult to assess due to uncertainty in the composition of the mixture. Overlaps between individual ions and regions in parameter space were identified, both between gas- and particle-phase measurements, and within each phase. These overlaps were conservatively found to account for little (<10%) of the measured mass. However, challenges in identifying overlaps and in accurately converting molecular formulas into chemical properties (such as volatility or reactivity) highlight a continued need to incorporate structural information into atmospheric measurements.

scholarly journals Highly oxygenated organic molecule cluster decomposition in atmospheric pressure interface time-of-flight mass spectrometers

2020 ◽  
Vol 13 (7) ◽  
pp. 3581-3593 ◽  
Author(s):  
Tommaso Zanca ◽  
Jakub Kubečka ◽  
Evgeni Zapadinsky ◽  
Monica Passananti ◽  
Theo Kurtén ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Systematic Error ◽  
Elemental Composition ◽  
Atmospheric Pressure ◽  
Organic Molecule ◽  
Time Of Flight ◽  
Molecular Clusters ◽  
Bonding Energy ◽  
Molecular Formula ◽  
Mass Spectrometers

Abstract. Identification of atmospheric molecular clusters and measurement of their concentrations by atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometers may be affected by systematic error due to possible decomposition of clusters inside the instrument. Here, we perform numerical simulations of decomposition in an APi-TOF mass spectrometers and formation in the atmosphere of a set of clusters which involve a representative kind of highly oxygenated organic molecule (HOM), with the molecular formula C10H16O8. This elemental composition corresponds to one of the most common mass peaks observed in experiments on ozone-initiated autoxidation of α-pinene. Our results show that decomposition is highly unlikely for the considered clusters, provided their bonding energy is large enough to allow formation in the atmosphere in the first place.

Atmospheric pressure chemical ionisation (APCI) and photoionisation (APPI) mass spectrometry for detection of unsaturated fatty acids: potential for rapid detection of adulteration of vegetable oils

2019 ◽  
Vol 11 (30) ◽  
pp. 3819-3828 ◽  
Author(s):  
Ilya Strashnov ◽  
Jamie D. Gilmour ◽  
Andrew Cannavan ◽  
Gang Chen ◽  
Champa Dissanayake ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Fatty Acids ◽  
Vegetable Oils ◽  
Atmospheric Pressure ◽  
Rapid Detection ◽  
Unsaturated Fatty Acids ◽  
Correction Factors ◽  
Pressure Chemical ◽  
The Difference ◽  
Chemical Ionisation

Unsaturated fatty acids of vegetable oils can be rapidly determined with APCI and APPI mass spectrometry by comparison to standards. The difference in the ionization efficiencies of FA can be addressed by calculation of correction factors.

scholarly journals Chemical characterisation of benzene oxidation products under high- and low-NO<sub><i>x</i></sub> conditions using chemical ionisation mass spectrometry

2021 ◽  
Vol 21 (5) ◽  
pp. 3473-3490
Author(s):  
Michael Priestley ◽  
Thomas J. Bannan ◽  
Michael Le Breton ◽  
Stephen D. Worrall ◽  
Sungah Kang ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
First Generation ◽  
Carbon Number ◽  
Oxidation Products ◽  
Benzene Oxidation ◽  
Volatile Organic ◽  
Cluster 2 ◽  
Chemical Ionisation ◽  
Ionisation Mass

Abstract. Aromatic hydrocarbons are a class of volatile organic compounds associated with anthropogenic activity and make up a significant fraction of urban volatile organic compound (VOC) emissions that contribute to the formation of secondary organic aerosol (SOA). Benzene is one of the most abundant species emitted from vehicles, biomass burning and industry. An iodide time-of-flight chemical ionisation mass spectrometer (ToF-CIMS) and nitrate ToF-CIMS were deployed at the Jülich Plant Atmosphere Chamber as part of a series of experiments examining benzene oxidation by OH under high- and low-NOx conditions, where a range of organic oxidation products were detected. The nitrate scheme detects many oxidation products with high masses, ranging from intermediate volatile organic compounds (IVOCs) to extremely low volatile organic compounds (ELVOCs), including C12 dimers. In comparison, very few species with C≥6 and O≥8 were detected with the iodide scheme, which detected many more IVOCs and semi-volatile organic compounds (SVOCs) but very few ELVOCs and low volatile organic compounds (LVOCs). A total of 132 and 195 CHO and CHON oxidation products are detected by the iodide ToF-CIMS in the low- and high-NOx experiments respectively. Ring-breaking products make up the dominant fraction of detected signal and 21 and 26 of the products listed in the Master Chemical Mechanism (MCM) were detected. The time series of highly oxidised (O≥6) and ring-retaining oxidation products (C6 and double-bond equivalent = 4) equilibrate quickly, characterised by a square form profile, compared to MCM and ring-breaking products which increase throughout oxidation, exhibiting sawtooth profiles. Under low-NOx conditions, all CHO formulae attributed to radical termination reactions of first-generation benzene products, and first-generation auto-oxidation products are observed. Several N-containing species that are either first-generation benzene products or first-generation auto-oxidation products are also observed under high-NOx conditions. Hierarchical cluster analysis finds four clusters, of which two describe photo-oxidation. Cluster 2 shows a negative dependency on the NO2/NOx ratio, indicating it is sensitive to NO concentration and thus likely to contain NO addition products and alkoxy-derived termination products. This cluster has the highest average carbon oxidation state (OSC‾) and the lowest average carbon number. Where nitrogen is present in a cluster member of cluster 2, the oxygen number is even, as expected for alkoxy-derived products. In contrast, cluster 1 shows no dependency on the NO2/NOx ratio and so is likely to contain more NO2 addition and peroxy-derived termination products. This cluster contains fewer fragmented species, as the average carbon number is higher and OSC‾ lower than cluster 2, and more species with an odd number of oxygen atoms. This suggests that clustering of time series which have features pertaining to distinct chemical regimes, for example, NO2/NOx perturbations, coupled with a priori knowledge, can provide insight into identification of potential functionality.

scholarly journals Real-time detection of highly oxidized organosulfates and BSOA marker compounds during the F–BEACh 2014 field study

2016 ◽  
Author(s):  
Martin Brüggemann ◽  
Laurent Poulain ◽  
Andreas Held ◽  
Torsten Stelzer ◽  
Christoph Zuth ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Field Study ◽  
Gas Phase ◽  
Organic Compounds ◽  
Atmospheric Pressure ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Aerosol Mass ◽  
Marker Compounds ◽  
Sulfur Containing

Abstract. The chemical composition of 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). Aerosols were analyzed in real-time by Aerosol Flowing Atmospheric-Pressure Afterglow Mass Spectrometry (AeroFAPA–MS), Aerosol Mass Spectrometry (AMS), and Chemical Ionization Atmospheric-Pressure interface Time-of-Flight Mass Spectrometry (CI–APiToF–MS). In addition, offline detection of acidic organic compounds was conducted by non-target screening of filter samples using High Resolution Mass Spectrometry (HRMS) in combination with Ultra-High Pressure Liquid Chromatography (UHPLC). In total, 93 acidic organic compounds were identified as characteristic contributors to the organic aerosol mass at the site. Among the carbon-, hydrogen-, oxygen-containing compounds, several common biogenic secondary organic aerosol (BSOA) marker compounds were detected. High concentrations were found for the monoterpene photooxidation products 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) and 3 carboxyheptanedioic acid, suggesting that α-/β-pinene and d-limonene oxidation products were dominating the organic aerosol fraction. In agreement, volatile organic compound (VOC) measurements showed high mixing ratios for these monoterpenes. Moreover, the high abundance of MBTCA and 3-carboxyheptanedioic acid and their concentration ratios to earlier-generation oxidation products, such as pinic acid, indicate that aged aerosol masses were present during the campaign period. HYSPLIT trajectory calculations revealed that most of the arriving air masses traveled long distances (>1,500 km) over land with high solar radiation, further supporting this hypothesis. Around 47 % of the detected compounds from the filter sample analysis were sulfur-containing, suggesting a 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 unambiguously identified. In addition, correlations among HOOS classes, sulfate and highly oxidized multifunctional organic compounds (HOMs) were investigated. The results support the hypothesis of previous studies that HOOS are formed by reactions of gas-phase HOMs with particulate sulfate. Furthermore, a good agreement was observed between HOOS formation and gas-phase peroxyradical (RO2•) concentrations, measured by the CI–APiTOF–MS. This finding suggests RO2• to be either a direct or indirect precursor for HOOS. In addition, periods with high relative humidity revealed that aqueous-phase chemistry might play a major role in HOOS production.

scholarly journals Chemical characterisation of benzene oxidation products under high and low NO<sub>x</sub> conditions using chemical ionisation mass spectrometry

2020 ◽  
Author(s):  
Michael Priestley ◽  
Thomas J. Bannan ◽  
Michael Le Breton ◽  
Stephen D. Worrall ◽  
Sungah Kang ◽  
...  
Keyword(s):  
Time Series ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Carbon Number ◽  
Oxidation Products ◽  
Benzene Oxidation ◽  
Volatile Organic ◽  
Cluster 2 ◽  
Chemical Ionisation ◽  
Ionisation Mass

Abstract. Aromatic hydrocarbons are a class of volatile organic compounds associated with anthropogenic activity and make up a significant fraction of urban VOC emissions that contribute to the formation of secondary organic aerosol (SOA). Benzene is one of the most abundant species emitted from vehicles, biomass burning and industry. An iodide time of flight chemical ionisation mass spectrometer (ToF-CIMS) and nitrate ToF-CIMS were deployed at the Jülich plant chamber as part of a series of experiments examining benzene oxidation by OH under high and low NOx conditions, where a range of organic oxidation products were detected. The nitrate scheme detects many oxidation products with high masses ranging from intermediate volatile organic compounds (IVOC) to extremely low volatile organic compounds (ELVOC), including C12 dimers. In comparison, very few species with C≥6 and O≥8 were detected with the iodide scheme, which detected many more IVOC and semi volatile organic compounds (SVOC) but very few ELVOC and low volatile organic compounds (LVOC). 132 and 195 CHO and CHON oxidation products are detected by the iodide ToF-CIMS in the low and high NOx experiments respectively. Ring breaking products make up the dominant fraction of detected signal (89–91 %). 21 and 26 of the products listed in the master chemical mechanism (MCM) were detected and account for 6.4–7.3 % of total signal. The time series of highly oxidised (O≥6) and ring retaining oxidation products (C6 and double bond equivalent = 4) equilibrate quickly characterised by a square form profile, compared to MCM and ring breaking products which increase throughout oxidation exhibiting saw tooth profiles. Under low NOx conditions, all CHO formulae attributed to radical termination reactions of 1st generation benzene products and 1st generation autoxidation products are observed, and one exclusively 2nd generation autoxidation product is also measured (C6H8O8). Several N containing species that are either 1st generation benzene products or 1st generation autoxidation products are also observed under high NOx conditions. Hierarchical cluster analysis finds four cluster of which two describe photo-oxidation. Cluster 2 shows a negative dependency on the NO2/NOx ratio indicating it is sensitive to NO concentration thus likely to contain NO addition products and alkoxy derived termination products. This cluster has the highest average carbon oxidation state (OSc) and the lowest average carbon number and where nitrogen is present in cluster member, the oxygen number is even, as expected for alkoxy derived products. In contrast, cluster 1 shows no dependency on the NO2/NOx ratio and so is likely to contain more NO2 addition and peroxy derived termination products. This cluster contains less fragmented species, as the average carbon number is higher and OSc lower than cluster 2, and more species with an odd number of oxygen atoms. This suggests clustering of time series which have features pertaining to distinct chemical regimes e.g. NO2/NOx perturbations, coupled with a priori knowledge, can provide insight into identification of potential functionality.

scholarly journals Molecular corridors and kinetic regimes in the multiphase chemical evolution of secondary organic aerosol

2014 ◽  
Vol 14 (16) ◽  
pp. 8323-8341 ◽  
Author(s):  
M. Shiraiwa ◽  
T. Berkemeier ◽  
K. A. Schilling-Fahnestock ◽  
J. H. Seinfeld ◽  
U. Pöschl
Keyword(s):  
Organic Compounds ◽  
Chemical Evolution ◽  
Molar Mass ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Transport Processes ◽  
Oxidation Products ◽  
Degree Of Saturation ◽  
Reaction Products ◽  
Full Spectrum

Abstract. The dominant component of atmospheric, organic aerosol is that derived from the oxidation of volatile organic compounds (VOCs), so-called secondary organic aerosol (SOA). SOA consists of a multitude of organic compounds, only a small fraction of which has historically been identified. Formation and evolution of SOA is a complex process involving coupled chemical reaction and mass transport in the gas and particle phases. Current SOA models do not embody the full spectrum of reaction and transport processes, nor do they identify the dominant rate-limiting steps in SOA formation. Based on molecular identification of SOA oxidation products, we show here that the chemical evolution of SOA from a variety of VOC precursors adheres to characteristic "molecular corridors" with a tight inverse correlation between volatility and molar mass. The slope of these corridors corresponds to the increase in molar mass required to decrease volatility by one order of magnitude (-dM / dlogC0). It varies in the range of 10–30 g mol−1, depending on the molecular size of the SOA precursor and the O : C ratio of the reaction products. Sequential and parallel reaction pathways of oxidation and dimerization or oligomerization progressing along these corridors pass through characteristic regimes of reaction-, diffusion-, or accommodation-limited multiphase chemical kinetics that can be classified according to reaction location, degree of saturation, and extent of heterogeneity of gas and particle phases. The molecular corridors and kinetic regimes help to constrain and describe the properties of the products, pathways, and rates of SOA evolution, thereby facilitating the further development of aerosol models for air quality and climate.

Sign in / Sign up

Export Citation Format

Share Document