Thermal Decomposition of Phospholipid Secondary Ozonides: Implications for the Toxicity of Inhaled Ozone

Pham, Bryan

doi:10.1080/089583798197475

Cited by 5 publications

(2 citation statements)

References 57 publications

(83 reference statements)

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“…Given that the structure of the m/ z 225 ion is ambiguous, we refer to it here (and in similar instances) as the “Criegee ion.” These ions may form via either the biradical mechanism (Scheme 2b) or by cycloreversion of the secondary ozonide (Scheme 2h). Both of these fragments are well known decomposition products of lipid secondary ozonides [20, 34]. …”

Section: Resultsmentioning

confidence: 99%

“…It is possible that activation of secondary ozonides, either thermally or by photolysis, can facilitate their decomposition into a number of lower mass components. Several studies have investigated the thermal decomposition of secondary ozonides in both the gas-phase and solution-phase, and in all cases aldehydes and carboxylic acids are observed as major products [20–25]. Studies by Hull et al [22] and Khachatryan et al [23] have provided evidence for a radical mechanism leading to the formation of aldehydes and carboxylic acids.…”

Section: Introductionmentioning

confidence: 99%

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Radical Generation from the Gas-Phase Activation of Ionized Lipid Ozonides

Ellis

Panhuis

Trevitt

et al. 2017

J. Am. Soc. Mass Spectrom.

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Reaction products from the ozonolysis of unsaturated lipids at gas–liquid interfaces have the potential to significantly influence the chemical and physical properties of organic aerosols in the atmosphere. In this study, the gas-phase dissociation behavior of lipid secondary ozonides is investigated using ion-trap mass spectrometry. Secondary ozonides were formed by reaction between a thin film of unsaturated lipids (fatty acid methyl esters or phospholipids) with ozone before being transferred to the gas phase as [M + Na]+ ions by electrospray ionization. Activation of the ionized ozonides was performed by either energetic collisions with helium buffer-gas or laser photolysis, with both processes yielding similar product distributions. Products arising from the decomposition of the ozonides were characterized by their mass-to-charge ratio and subsequent ion-molecule reactions. Product assignments were rationalized as arising from initial homolysis of the ozonide oxygen–oxygen bond with subsequent decomposition of the nascent biradical intermediate. In addition to classic aldehyde and carbonyl oxide-type fragments, carbon-centered radicals were identified with a number of decomposition pathways that indicated facile unimolecular radical migration. These findings reveal that photoactivation of secondary ozonides formed by the reaction of aerosol-bound lipids with tropospheric ozone may initiate radical-mediated chemistry within the particle resulting in surface modification. Graphical Abstractᅟ Electronic supplementary materialThe online version of this article (doi:10.1007/s13361-017-1649-4) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Radical Generation from the Gas-Phase Activation of Ionized Lipid Ozonides

Ellis

Panhuis

Trevitt

et al. 2017

J. Am. Soc. Mass Spectrom.

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Multiphase Ozonolysis of Oleic Acid-Based Lipids: Quantitation of Major Products and Kinetic Multilayer Modeling

Zhou

Lakey

Domaros

et al. 2022

Environ. Sci. Technol.

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Commonly found in atmospheric aerosols, cooking oils, and human sebum, unsaturated lipids rapidly decay upon exposure to ozone, following the Criegee mechanism. Here, the gassurface ozonolysis of three oleic acid-based compounds was studied in a reactor and indoors. Under dry conditions, quantitative product analyses by 1 H NMR indicate up to 79% molar yield of stable secondary ozonides (SOZs) in oxidized triolein and methyl oleate coatings. Elevated relative humidity (RH) significantly suppresses the SOZ yields, enhancing the formation of condensed-phase aldehydes and volatile C9 products. Along with kinetic parameters informed by molecular dynamics simulations, these results were used as constraints in a kinetic multilayer model (KM-GAP) simulating triolein ozonolysis. Covering a wide range of coating thicknesses and ozone levels, the model predicts a much faster decay near the gas−lipid interface compared to the bulk. Although the dependence of RH on SOZ yields is well predicted, the model overestimates the production of H 2 O 2 and aldehydes. With negligible dependence on RH, the product composition for oxidized oleic acid is substantially affected by a competitive reaction between Criegee intermediates (CIs) and carboxylic acids. The resulting α-acyloxyalkyl hydroperoxides (α-AAHPs) have much higher molar yields (29−38%) than SOZs (12−16%). Overall, the ozone−lipid chemistry could affect the indoor environment through "crust" accumulation on surfaces and volatile organic compound (VOC) emission. In the atmosphere, the peroxide formation and changes in particle hygroscopicity may have effects on climate. The related health impacts are also discussed.

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Secondary Ozonide Formation from the Ozone Oxidation of Unsaturated Self-Assembled Monolayers on Zinc Selenide Attenuated Total Reflectance Crystals

2009

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The ozone oxidation of terminal unsaturated 7-octenyltrichlorosilane self-assembled monolayers (C8= SAMs) on ZnSe and on SiO x -coated ZnSe was followed as a function of time using Fourier transform infrared spectroscopy (FTIR). Zinc selenide substrates have a major advantage over silicon crystals used in previous studies in that they transmit to approximately 650 cm−1, well beyond the cutoff of ∼1500 cm−1 for silicon ATR crystals, and thus allow detection of additional product species. When uncoated ZnSe or SiO x -coated ZnSe ATR crystals with a C8= SAM are exposed to gaseous ozone at concentrations from 1013 to 1015 molecules cm−3 at 1 atm pressure in He at 296 K, peaks due to CCH decrease and a strong product peak at 1110 cm−1 as well as a weaker peak at 1385 cm−1 increase, both of which are attributed to the formation of a stable secondary ozonide (1,2,4-trioxolane, SOZ). Peaks at 2860 and 2929 cm−1 are also formed, which we tentatively assign to the C−H stretch of the OC−H group in the SOZ. The magnitude of the 1110 cm−1 band relative to those due to carbonyl groups at ∼1722 cm−1 suggests that SOZ may, in fact, be the major reaction product. The SOZ has a sufficiently long lifetime when formed in the condensed phase that it is stabilized on the surface, indicating secondary ozonides may be formed during organic oxidations on surfaces in the atmosphere.

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Thermal Decomposition of Phospholipid Secondary Ozonides: Implications for the Toxicity of Inhaled Ozone

Cited by 5 publications

References 57 publications

Radical Generation from the Gas-Phase Activation of Ionized Lipid Ozonides

Radical Generation from the Gas-Phase Activation of Ionized Lipid Ozonides

Multiphase Ozonolysis of Oleic Acid-Based Lipids: Quantitation of Major Products and Kinetic Multilayer Modeling

Secondary Ozonide Formation from the Ozone Oxidation of Unsaturated Self-Assembled Monolayers on Zinc Selenide Attenuated Total Reflectance Crystals

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