Comment on “Letter to the Editor regarding,'Polyfluorinated

Feb 21, 2013 - Authors approve of changes prior to publication. The authors declare no competing financial interest. □ REFERENCES. (1) Cousins, I. T...
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Comment on “Letter to the Editor regarding, ‘Polyfluorinated Compounds: Past, Present, and Future’”

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n their article, Cousins and Buck1 make the following statement: “The physical-chemical (e.g., water solubility, acid dissociation constants) and biological (e.g., toxicology, bioaccumulation) properties of individual homologues in the homologous series of perfluoroalkane sulfonates (PFSAs) and perfluoroalkyl carboxylates (PFCAs) vary greatly with carbon chain length.” As has been previously shown, there is no significant change in the acid dissociation constants of PFCAs or PFSAs between various perfluoroalkyl chain length homologues.2−6

Sierra Rayne*

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Chemologica Research, PO Box 74, 318 Rose Street, Mortlach, Saskatchewan S0H 3EO, Canada

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*E-mail: [email protected]. Tel.: + (1) 306 690 0573. Fax: + (1) 306 690 0573. Notes

Environmental Science & Technology edits all Letters for length, punctuation, and clarification of references. Authors approve of changes prior to publication. The authors declare no competing financial interest.

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REFERENCES

(1) Cousins, I. T.; Buck, R. C. Letter to the Editor regarding, “Polyfluorinated Compounds: Past, Present, and Future”. Environ. Sci. Technol. 2011, 45, 9821−9821. (2) Rayne, S.; Forest, K. Theoretical Studies on the pKa Values of Perfluoroalkyl Carboxylic Acids. J. Mol. Struct.: THEOCHEM 2010, 949, 60−69. (3) Goss, K. U. The pKa Values of PFOA and Other Highly Fluorinated Carboxylic Acids. Environ. Sci. Technol. 2008, 42, 456− 458. (4) Goss, K. U. Correction: The pKa Values of PFOA and Other Highly Fluorinated Carboxylic Acids. Environ. Sci. Technol. 2008, 42, 5032−5032. (5) Cheng, J.; Psillakis, E.; Hoffmann, M. R.; Colussi, A. J. Acid Dissociation versus Molecular Association of Perfluoroalkyl Oxoacids: Environmental Implications. J. Phys. Chem. A 2009, 113, 8152−8156. (6) Rayne, S.; Forest, K.; Friesen, K. J. Extending the Semi-Empirical PM6 Method for Carbon Oxyacid pKa Prediction to Sulfonic Acids: Application Towards Congener-Specific Estimates for the Environmentally and Toxicologically Relevant C1 through C8 Perfluoroalkyl Derivatives. Nat. Precedings 2009, DOI: 10101/npre.2009.2922.1.

Published: February 21, 2013 © 2013 American Chemical Society

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dx.doi.org/10.1021/es400475a | Environ. Sci. Technol. 2013, 47, 2151−2151