Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published August 6, 2009 | Supplemental Material + Erratum
Journal Article Open

Enrichment Factors of Perfluoroalkyl Oxoanions at the Air/Water Interface


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.

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 http://pubs.acs.org.



Attached Files

Supplemental Material - jp902795m_si_001.pdf

Erratum - jp9058559.pdf


Files (85.9 kB)
Name Size Download all
11.1 kB Preview Download
74.8 kB Preview Download

Additional details

August 20, 2023
October 18, 2023