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Polyfluorinated Amides as a Historical PFCA Source by Electrochemical Fluorination of Alkyl Sulfonyl Fluorides
journal contribution
posted on 2013-01-02, 00:00 authored by Derek
A. Jackson, Scott A. MaburyPolyfluorinated amides (PFAMs) are a class of compounds
produced
as byproducts of polyfluorinated sulfonamide synthesis by electrochemical
fluorination (ECF). We measured four PFAM derivatives of perfluorooctanoic
acid (PFOA) in a wide range of compounds, experimental materials,
and commercial products synthesized by ECF. Initial screening was
performed using headspace solid phase microextraction gas chromatography
mass spectrometry (SPME-GC-MS), and quantification using in-house
synthesized standards was accomplished with GC-MS using positive chemical
ionization. Two monosubstituted PFAMs, N-methylperfluorooctanamide
(MeFOA) and N-ethylperfluorooctanamide (EtFOA), were
detected in the majority of materials that were analyzed. Two disubstituted
PFAMs, N-methyl-N-(2-hydroxyethyl)perfluorooctanamide
(MeFOAE) and N-ethyl-N-(2-hydroxyethyl)perfluorooctanamide
(EtFOAE), were not detected in any sample, likely because they were
never synthesized. The concentrations of PFAMs in the sulfonamide
compounds under study ranged from 12 to 6736 μg/g, suggesting
their historical importance as PFCA precursors. In each case, branched
isomers for PFAMs were detected, providing further support for their
link to an ECF source. A hydrolysis study performed at pH 8.5 showed
no degradation of EtFOA to PFOA after 8 days due to the stability
of the amide bond. The environmental fate of PFAMs is suggested to
be volatilization to the atmosphere followed by oxidation by hydroxyl
radical with a predicted lifetime of 3–20 days. Subsequent
PFAM exposure to biota will likely lead to enzymatic hydrolysis of
the amide linkage to give a PFCA. Human exposure to PFAMs may have
contributed to the presence of branched PFOA isomers in blood by serving
as an indirect source. The decline in PFOA concentrations in human
blood is consistent with a significant drop in PFAM production concurrent
with the POSF phase-out in 2000–2001.
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POSFelectrochemical fluorinationchemical ionizationamide linkageperfluorooctanoic acidPFOA isomersPolyfluorinated AmidesHuman exposureHistorical PFCA Source8 daysPFOA concentrationsECF sourceamide bondPFCA precursorsSubsequent PFAM exposurePFAM derivativesPFAM productionElectrochemical FluorinationAlkyl Sulfonyl FluoridesPolyfluorinated amidesInitial screeningsulfonamide compoundspH 8.5hydrolysis studymonosubstituted PFAMsphase microextraction gas chromatography mass spectrometrydisubstituted PFAMspolyfluorinated sulfonamide synthesis
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