High molecular weight SOA formation during limonene ozonolysis: insights from ultrahigh-resolution FT-ICR mass spectrometry characterization

Abstract. The detailed molecular composition of secondary organic aerosols (SOA) from limonene ozonolysis was studied using ultrahigh-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. High molecular weight (MW) compounds (m/z > 300) were found to constitute a significant number fraction of the identified SOA components. Double bond equivalents (DBE = the number of rings plus the number of double bonds) increased with MW. The O:C ratios and relative abundances of compounds decreased with increasing MW. The mass spectra of limonene contain 4 distinct clusters of negative ions: Group I (140 < m/z < 300), Group II (300 < m/z < 500), Group III (500 < m/z < 700) and Group IV (700 < m/z < 850). A number of CH2 and O homologous series of low MW SOA (Group 1) with carbon number 7–15 and oxygen number 3–9 were observed. Their occurrence can be explained with isomerization and elimination reactions of Criegee radicals, reactions between alkyl peroxy radicals, and scission of alkoxy radicals resulting from the Criegee radicals. Additionally, fragmentation analysis and observations of formaldehyde homologous series provide evidence for aerosol growth by the reactive uptake of generated gas-phase carbonyls in limonene ozonolysis. The decreasing O:C ratios between group of compounds indicated the importance of condensation (aldol and esterification) reaction pathways for high MW compound formation. However, the prominent DBE changes of 2 between the groups of compounds and selected fragmentation (MS/MS) analysis of Group II and Group III ions indicated a predominance of non-condensation (hydroperoxide, Criegee and hemi-acetal) reaction pathways. A reaction matrix created with the combination of low MW SOA, hydroperoxides, and Criegee radicals indicated higher frequencies for the hemi-acetal and condensation reaction pathways. Overall, the combined approach confirms the importance of non-condensation reaction pathways over condensation reaction pathways. Among the non-condensation reaction pathways, hemi-acetal reactions appear to be most dominant followed by hydroperoxide and Criegee reactions.

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High molecular weight SOA formation during limonene ozonolysis: insights from ultrahigh-resolution FT-ICR mass spectrometry characterization

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-5523-2012 ◽

2012 ◽

Vol 12 (12) ◽

pp. 5523-5536 ◽

Cited By ~ 64

Author(s):

S. Kundu ◽

R. Fisseha ◽

A. L. Putman ◽

T. A. Rahn ◽

L. R. Mazzoleni

Keyword(s):

Mass Spectrometry ◽

Molecular Weight ◽

Gas Phase ◽

Homologous Series ◽

Radical Reaction ◽

Building Blocks ◽

Molecular Formula ◽

Ultrahigh Resolution ◽

Reaction Channels ◽

Ft Icr

Abstract. The detailed molecular composition of laboratory generated limonene ozonolysis secondary organic aerosol (SOA) was studied using ultrahigh-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Approximately 1200 molecular formulas were identified in the SOA over the mass range of 140 to 850 Da. Four characteristic groups of high relative abundance species were observed; they indicate an array of accretion products that retain a large fraction of the limonene skeleton. The identified molecular formulas of each of the groups are related to one another by CH2, O and CH2O homologous series. The CH2 and O homologous series of the low molecular weight (MW) SOA (m/z < 300) are explained with a combination of functionalization and fragmentation of radical intermediates and reactive uptake of gas-phase carbonyls. They include isomerization and elimination reactions of Criegee radicals, reactions between alkyl peroxy radicals, and scission of alkoxy radicals resulting from the Criegee radicals. The presence of compounds with 10–15 carbon atoms in the first group (e.g. C11H18O6) provides evidence for SOA formation by the reactive uptake of gas-phase carbonyls during limonene ozonolysis. The high MW compounds (m/z > 300) were found to constitute a significant number fraction of the identified SOA components. The formation of high MW compounds was evaluated by molecular formula trends, fragmentation analysis of select high MW compounds and a comprehensive reaction matrix including the identified low MW SOA, hydroperoxides and Criegee radicals as building blocks. Although the formation of high MW SOA may occur via a variety of radical and non-radical reaction channels, the combined approach indicates a greater importance of the non-condensation reactions over aldol and ester condensation reaction channels. Among these hemi-acetal reactions appear to be most dominant followed by hydroperoxide and Criegee reaction channels.

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Geochemistry of High-Molecular Weight Dimethylalkanes

Russian Geology and Geophysics ◽

10.2113/rgg20204319 ◽

2021 ◽

Vol 62 (08) ◽

pp. 866-877

Author(s):

V.A. Kashirtsev ◽

O.S. Dzyuba ◽

B.L. Nikitenko ◽

E.A. Kostyreva ◽

I.K. Ivanova ◽

...

Keyword(s):

Mass Spectrometry ◽

Molecular Weight ◽

Organic Matter ◽

High Molecular Weight ◽

Homologous Series ◽

Russian Platform ◽

Microbial Origin ◽

Carbon Chains ◽

Chromatography Mass Spectrometry ◽

Related Compounds

Abstract —The homologous series of high-molecular weight dimethylalkanes (HMWDMAs) with either odd- or even-numbered carbon chains in the range from C19–20 to C30–31 have been identified in organic matter from recent and partially lithified deposits of Siberia and the Russian Platform by chromatography–mass spectrometry. The first homologous series is represented by even-numbered 3,4-HMWDMAs followed by the alternation of odd-numbered 3,5-HMWDMAs, even-numbered 3,6-HMWDMAs, and odd-numbered 3,7-HMWDMAs. The most abundant are 3,7-dimethylalkanes. The microbial origin of high-molecular weight dimethylalkanes is the most likely explanation for their presence in the fossil organic matter. The precursors of HMWDMAs might have been tetra- and diether lipids of archaea and bacteria. It is assumed that HMWDMAs and other immature hydrocarbons from great depths (SV-27 and SG-6 superdeep boreholes) result from the decomposition of asphaltenes, which occluded the related compounds inside their structure during the early stages of generation and carried them unchanged throughout the “oil window”.

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