Photosensitized Reactions of a Phenolic Carbonyl from Wood Combustion in the Aqueous Phase-Chemical Evolution and Light Absorption Properties of AqSOA.
Wenqing JiangMaria V MisovichAnusha Priyadarshani Silva HettiyaduraAlexander LaskinAlexander S McFallCort AnastasioQi ZhangPublished in: Environmental science & technology (2021)
Guaiacyl acetone (GA) is a phenolic carbonyl emitted in significant quantities by wood combustion that undergoes rapid aqueous-phase oxidation to produce aqueous secondary organic aerosol (aqSOA). We investigate the photosensitized oxidation of GA by an organic triplet excited state (3C*) and the formation and aging of the resulting aqSOA in wood smoke-influenced fog/cloud water. The chemical transformations of the aqSOA were characterized in situ using a high-resolution time-of-flight aerosol mass spectrometer. Additionally, aqSOA samples collected over different time periods were analyzed using high-performance liquid chromatography coupled with a photodiode array detector and a high-resolution Orbitrap mass spectrometer (HPLC-PDA-HRMS) to provide details on the molecular composition and optical properties of brown carbon (BrC) chromophores. Our results show efficient formation of aqSOA from GA, with an average mass yield around 80%. The composition and BrC properties of the aqSOA changed significantly over the course of reaction. Three generations of aqSOA products were identified via positive matrix factorization analysis of the aerosol mass spectrometry data. Oligomerization and functionalization dominated the production of the first-generation aqSOA, whereas fragmentation and ring-opening reactions controlled the formation of more oxidized second- and third-generation products. Significant formation of BrC was observed in the early stages of the photoreaction, while organic acids were produced throughout the experiment. High-molecular weight molecules (m/z > 180) with high aromaticity were identified via HPLC-PDA-HRMS and were found to account for a majority of the UV-vis absorption of the aqSOA.
Keyphrases
- high resolution
- high performance liquid chromatography
- mass spectrometry
- tandem mass spectrometry
- liquid chromatography
- ultra high performance liquid chromatography
- pet ct
- water soluble
- simultaneous determination
- high resolution mass spectrometry
- gas chromatography
- solid phase extraction
- ms ms
- capillary electrophoresis
- ionic liquid
- magnetic resonance imaging
- electronic health record
- cell wall
- hydrogen peroxide
- computed tomography
- big data
- high speed
- machine learning
- sewage sludge
- deep learning
- high throughput
- magnetic resonance