According to the pseudo-ideal mixing assumption employed in practically all chemical transport models, organic aerosol components from different sources interact with each other in a single solution, independent of their composition. This critical assumption greatly affects modeled organic aerosol concentrations, but there is little direct experimental evidence to support it. A main experimental challenge is that organic aerosol components from different sources often look similar when analyzed with an aerosol mass spectrometer. We developed a new experimental method to overcome this challenge, using isotopically labeled compounds ( 13C or D) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). We generated mixtures of secondary organic aerosol (SOA) from isotopically labeled toluene and from unlabeled α-pinene and used the HR-ToF-AMS data to separate these different SOA types. We evaluated their interaction by comparing the aerosol mass yields of toluene and α-pinene when the SOA was formed in these mixtures to their yields when the SOA was formed in isolation. At equilibrium, our results are consistent with pseudo-ideal mixing of anthropogenic and biogenic SOA components from these chemically dissimilar precursors. © 2011 American Chemical Society.
CITATION STYLE
Hildebrandt, L., Henry, K. M., Kroll, J. H., Worsnop, D. R., Pandis, S. N., & Donahue, N. M. (2011). Evaluating the mixing of organic aerosol components using high-resolution aerosol mass spectrometry. Environmental Science and Technology, 45(15), 6329–6335. https://doi.org/10.1021/es200825g
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