| Title: | Quantification of Gas-Wall Partitioning in Teflon Environmental Chambers Using Rapid Bursts of Low-Volatility Oxidized Species Generated in Situ |
| Author(s): | Krechmer JE; Pagonis D; Ziemann PJ; Jimenez JL; |
| Address: | "Cooperative Institute for Research in Environmental Sciences (CIRES) , Boulder, Colorado 80309, United States. Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States" |
| ISSN/ISBN: | 1520-5851 (Electronic) 0013-936X (Linking) |
| Abstract: | "Partitioning of gas-phase organic compounds to the walls of Teflon environmental chambers is a recently reported phenomenon than can affect the yields of reaction products and secondary organic aerosol (SOA) measured in laboratory experiments. Reported time scales for reaching gas-wall partitioning (GWP) equilibrium (tauGWE) differ by up to 3 orders of magnitude, however, leading to predicted effects that vary from substantial to negligible. A new technique is demonstrated here in which semi- and low-volatility oxidized organic compounds (saturation concentration c* < 100 mug m(-3)) were photochemically generated in rapid bursts in situ in an 8 m(3) environmental chamber, and then their decay in the absence of aerosol was measured using a high-resolution chemical ionization mass spectrometer (CIMS) equipped with an 'inlet-less' NO3(-) ion source. Measured tauGWE were 7-13 min (rel. std. dev. 33%) for all compounds. The fraction of each compound that partitioned to the walls at equilibrium follows absorptive partitioning theory with an equivalent wall mass concentration in the range 0.3-10 mg m(-3). Measurements using a CIMS equipped with a standard ion-molecule reaction region showed large biases due to the contact of compounds with walls. On the basis of these results, a set of parameters is proposed for modeling GWP in chamber experiments" |
| Keywords: | Aerosols *Air Pollutants Organic Chemicals/chemistry Polytetrafluoroethylene *Volatilization; |
| Notes: | "MedlineKrechmer, Jordan E Pagonis, Demetrios Ziemann, Paul J Jimenez, Jose L eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2016/05/04 Environ Sci Technol. 2016 Jun 7; 50(11):5757-65. doi: 10.1021/acs.est.6b00606. Epub 2016 May 17" |
