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Synthesis of Carboxylic Acid and Dimer Ester Surrogates to Constrain the Abundance and Distribution of Molecular Products in α-Pinene and β-Pinene Secondary Organic Aerosol

Kenseth, Christopher M. and Hafeman, Nicholas J. and Huang, Yuanlong and Dalleska, Nathan F. and Stoltz, Brian M. and Seinfeld, John H. (2020) Synthesis of Carboxylic Acid and Dimer Ester Surrogates to Constrain the Abundance and Distribution of Molecular Products in α-Pinene and β-Pinene Secondary Organic Aerosol. Environmental Science and Technology, 54 (20). pp. 12829-12839. ISSN 0013-936X. https://resolver.caltech.edu/CaltechAUTHORS:20200819-162804852

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[img] PDF (Adjustment of mass fractions in published LC/(−)ESI-MS studies of SOA from α-pinene ozonolysis; Tables S1–S4 and Figures S1–S3; synthetic procedures, characterization data, and NMR and IR spectra for carboxylic acids 1–3, dimer esters 4–6, and all...) - Supplemental Material
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Abstract

Liquid chromatography/negative electrospray ionization mass spectrometry [LC/(−)ESI-MS] is routinely employed to characterize the identity and abundance of molecular products in secondary organic aerosol (SOA) derived from monoterpene oxidation. Due to a lack of authentic standards, however, commercial terpenoic acids (e.g., cis-pinonic acid) are typically used as surrogates to quantify both monomeric and dimeric SOA constituents. Here, we synthesize a series of enantiopure, pinene-derived carboxylic acid and dimer ester homologues. We find that the (−)ESI efficiencies of the dimer esters are 19–36 times higher than that of cis-pinonic acid, demonstrating that the mass contribution of dimers to monoterpene SOA has been significantly overestimated in past studies. Using the measured (−)ESI efficiencies of the carboxylic acids and dimer esters as more representative surrogates, we determine that molecular products measureable by LC/(−)ESI-MS account for only 21.8 ± 2.6% and 18.9 ± 3.2% of the mass of SOA formed from ozonolysis of α-pinene and β-pinene, respectively. The 28–36 identified monomers (C₇₋₁₀H₁₀₋₁₈O₃₋₆) constitute 15.6–20.5% of total SOA mass, whereas only 1.3–3.3% of the SOA mass is attributable to the 46–62 identified dimers (C₁₅₋₁₉H₂₄₋₃₂O₄₋₁₁). The distribution of identified α-pinene and β-pinene SOA molecular products is examined as a function of carbon number (n_C), average carbon oxidation state (OS_C), and volatility (C*). The observed order-of-magnitude difference in (−)ESI efficiency between monomers and dimers is expected to be broadly applicable to other biogenic and anthropogenic SOA systems analyzed via (−) or (+) LC/ESI-MS under various LC conditions, and demonstrates that the use of unrepresentative surrogates can lead to substantial systematic errors in quantitative LC/ESI-MS analyses of SOA.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/acs.est.0c01566DOIArticle
ORCID:
AuthorORCID
Kenseth, Christopher M.0000-0003-3188-2336
Hafeman, Nicholas J.0000-0001-7525-7597
Huang, Yuanlong0000-0002-6726-8904
Dalleska, Nathan F.0000-0002-2059-1587
Stoltz, Brian M.0000-0001-9837-1528
Seinfeld, John H.0000-0003-1344-4068
Additional Information:© 2020 American Chemical Society. Received: March 13, 2020; Revised: August 5, 2020; Accepted: August 19, 2020; Published: August 19, 2020. We thank John Crounse and Paul Wennberg for useful discussions. UPLC/(−)ESI-Q-TOF-MS was performed in the Caltech Environmental Analysis Center (EAC). This work was supported by National Science Foundation Grants AGS-1523500, CHE-1800511, and CHE-1905340. The EAC is supported by the Linde Center and Beckman Institute at Caltech. Author Contributions: C.M.K. designed research; C.M.K. and Y.H. performed research; C.M.K., N.J.H., and B.M.S. contributed new reagents; C.M.K., Y.H., and N.F.D. analyzed data; and C.M.K. and J.H.S. wrote the paper. The authors declare no competing financial interest. Editor’s Note: This manuscript was selected for a C. Ellen Gonter Environmental Chemistry Award from the ACS Division of Environmental Chemistry.
Funders:
Funding AgencyGrant Number
NSFAGS-1523500
NSFCHE-1800511
NSFCHE-1905340
Ronald And Maxine Linde Center for Global Environmental ScienceUNSPECIFIED
Caltech Beckman InstituteUNSPECIFIED
Issue or Number:20
Record Number:CaltechAUTHORS:20200819-162804852
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200819-162804852
Official Citation:Synthesis of Carboxylic Acid and Dimer Ester Surrogates to Constrain the Abundance and Distribution of Molecular Products in α-Pinene and β-Pinene Secondary Organic Aerosol. Christopher M. Kenseth, Nicholas J. Hafeman, Yuanlong Huang, Nathan F. Dalleska, Brian M. Stoltz, and John H. Seinfeld. Environmental Science & Technology 2020 54 (20), 12829-12839; DOI: 10.1021/acs.est.0c01566
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105043
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:20 Aug 2020 14:31
Last Modified:21 Oct 2020 19:46

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