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Enrichment Factors of Perfluoroalkyl Oxoanions at the Air/Water Interface

Psillakis, Elefteria and Cheng, Jie and Hoffmann, M. R. and Colussi, A. J. (2009) Enrichment Factors of Perfluoroalkyl Oxoanions at the Air/Water Interface. Journal of Physical Chemistry A, 113 (31). pp. 8826-8829. ISSN 1089-5639.

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The refractory, water-bound perfluoro-n-alkyl carboxylate F(CF_2)_nCO_2^− and sulfonate F(CF_2)_nSO_3^− surfactant anions reach remote locations by mechanisms that are not well understood. Here we report experiments in which the relative concentrations of these anions on the surface of microdroplets produced by nebulizing their aqueous solutions are measured via electrospray ionization mass spectrometry. Enrichment factors f (relative to Br^−: f(Br^−) ≡ 1) increase with n, asymptotically reaching f[F(CF_2)_nSO_3^−] ~2f[F(CF_2)_nCO_2^−] ~200 f(Br^−) values above n ~ 8. The larger f values for F(CF_2)_nSO_3^− over their F(CF_2)_nCO_2^− congeners are consistent with a closer approach of the bulkier, less hydrated −SO_3^− headgroup to the air/water interface. A hyperbolic, rather than the predicted linear log f[F(CF_2)_nCO_2^−] vs n dependence suggests the onset of conformational restrictions to interfacial enrichment above n ~4. Marine aerosols produced from contaminated ocean surface waters are therefore expected to be highly enriched in F(CF_2)_nCO_2^−/F(CF_2)_nSO_3^− species.

Item Type:Article
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URLURL TypeDescription
Psillakis, Elefteria0000-0002-5867-3940
Hoffmann, M. R.0000-0001-6495-1946
Colussi, A. J.0000-0002-3400-4101
Additional Information:Copyright © 2009 American Chemical Society. Received: March 27, 2009; Revised Manuscript Received: May 19, 2009. Publication Date (Web): May 29, 2009. This project was financially supported by the National Science Foundation (ATM-0534990). E.P. is grateful to the Fullbright Foundation for financial support. Note Added after ASAP Publication. The Addition and Correction (DOI: 10.1021/jp9058559) for this Letter appears in the same issue. Supporting Information Available: Additional table of relative anion enrichment factors f at the air/water interface. This material is available free of charge via the Internet at
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Fulbright FoundationUNSPECIFIED
Issue or Number:31
Record Number:CaltechAUTHORS:20090817-144816269
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15107
Deposited By: George Porter
Deposited On:08 Sep 2009 17:49
Last Modified:09 Mar 2020 13:19

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