High-Resolution Mass Spectroscopic Analysis of Secondary Organic Aerosol Generated by Ozonolysis of Isoprene

Journal Article · Mon Feb 01 00:00:00 EST 2010 · Atmospheric Environment

DOI:https://doi.org/10.1016/j.atmosenv.2009.12.019· OSTI ID:974932

Nguyen, Tran B; Bateman, Adam P; Bones, David L; Nizkorodov, Serguei; Laskin, Julia; Laskin, Alexander

The chemical composition of secondary organic aerosol (SOA) generated from the ozonolysis of isoprene (C₅H₈) in the presence of an OH scavenger was examined using high-resolution electrospray ionization mass spectrometry (ESI-MS). The chemical composition of SOA is complex, with more than 1000 assigned peaks observed in the positive and negative ion mode spectra. Only a small fraction of peaks corresponds to known products of isoprene oxidation, such as pyruvic acid, glycolic acid, methylglyoxal, etc. The absolute majority of the detected peaks correspond to highly oxidized oligomeric constituents of SOA, with an average O:C molar ratio of ~0.6. The corresponding organic mass (OM) to organic oxygen (OO) ratio is OM/OO ~2.4. Approximately 8% of oxygen atoms in SOA are in the form of peroxides as quantified with an iodide test. Double bond equivalency (DBE) factors, representing the sum of all double bonds and rings, increase by 1 for every 2-3 additional carbon atoms in the molecule. The prevalent oligomer building blocks are therefore carbonyls or carboxylic acids with a C₂-C₃ skeleton. Kendrick analysis suggests that simple aldehydes, specifically formaldehyde, acetaldehyde, and methylglyoxal can serve as monomeric building blocks in the observed oligomers. The large number of reactive functional groups, especially organic peroxides and carbonyls, suggests that isoprene/O₃ SOA should be prone to chemical and photochemical aging.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 974932
• Report Number(s): PNNL-SA-69209; ATENBP; 30466; 24392; KP1704020; TRN: US201007%%891
• Journal Information: Atmospheric Environment, Vol. 44, Issue 8; ISSN 0004-6981
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACETALDEHYDE
AEROSOLS
AGING
ALDEHYDES
ANIONS
ATOMS
CARBON
CARBONYLS
CARBOXYLIC ACIDS
CHEMICAL COMPOSITION
DOUBLE BONDS
FORMALDEHYDE
GLYCOLIC ACID
IODIDES
IONIZATION
ISOPRENE
MASS SPECTROSCOPY
OXIDATION
OXYGEN
PEROXIDES
PYRUVIC ACID
SKELETON
biogenic aerosol
SOA
gas-particle partitioning
peroxides
carbonyls
organic carbon
oligomers
Environmental Molecular Sciences Laboratory