Fluorotelomer sulfonic acids

Fluorotelomer sulfonic acids have the general structure F(CF2) CH2CH2S03H, where usually = 6, 8 or 10 (Table 3.1). Similar to FTCAs/FTUCAs, FTSs are also named based on the ratio of fluorinated carbons to hydrogenated carbons in the molecule. The 6 2 FTS is also known by the abbreviation of THPFOS. Similar to PFSAs, it is expected that FTSs will dissociate in the environment ... 

Polyfluorinated compounds comprise hundreds of chemicals characterized by hydrophobic linear alkyl chains partially or fully fluorinated (as the perfluorinated compounds [PFCs]) and containing different functional groups. Polyfluorinated compounds include perfluoroalkyl sulfonamides (PFASAs), fluorotelomer alcohols (FTOHs), polyfluorinated alkyl phosphates (PFAPs), fluorotelomer unsaturated carboxylic acids (FTUCAs), perfluoroalkyl acids (PFAAs), and their salts. The most common PFAAs are perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFASs). In particular, PFASs contain one or more fluorinated alkyl chains bonded to a polar head, which at neutral pH can be charged (anionic, cationic, and amphiphilic surfactants) or noncharged (nonionic surfactants). 

Three subcategories are commonly used to classify PFASs per-fluoroalkyl sulfonic acids (PFSAs), perfluoroalkylcarboxylic acids (PFCAs), and fluorotelomer alcohols (FTOHs). Historically, PFSAs and PFCAs have been prepared by electrochemical fluorination, whereas fluorotelomer alcohols are s)mthesized by telomerization [146]. The electrochemical fluorination process results primarily in straight chain homologs, but branched chain isomers are known to be present. Branched chain isomers can also be s)mthesized through telomerization s)mthesis with the use of branched chain telogen precursors. FTOHs have an even number of carbon atoms and contain a nonfluorinated ethylene group adjacent to the polar end group. Pathways for the conversion of FTOHs fo PFCAs in the environment have been proposed [147,148]. 

Perfluoroalkyl acids (PFAs) are synthetic, perfluorinated, straight- or bran-ched-chain organic acids characterized by a carboxylate or sulfonate moiety [1]. PFAs are manufactured directly but can also be formed through transformation of many precursor molecules containing a perfluoroalkyl moiety [2], These include fluorotelomer alcohols (FTOHs) and perfluoroalkyl-sulfonamides (Table 1, Fig. 1), however, others likely exist. Collectively, this family of chemicals including PFAs and their polyfluorinated precursors will be referred to in this document as perfluoroalkyl substances (PFSs). 

Gumge, K. S., Taniyasu, S., Yamashita, N., Manage, P. M. Occurrence of perfluorinated acids and fluorotelomers in waters from Sri Lanka. Marine Pollution Bulletin, 54 1663-1672 (2007). Kannan, K., Koistinen, J., Beckmen, K., Evans, T., Jones, P. D., Eero, H., et al Accumulation of perfluorooctane sulfonate in marine mammals. Environmental Science and Technology, 35 1593-1598 (2001). 

Abstract In the past years, elucidation of transformation products of per- and polyfluorinated chemicals (PFC) has been a task frequently approached by analytical chemists. PCT, such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are persistent and thus, the analytical quest to detect transformation products has failed so far. Their prominence as contaminants is mainly due to their extreme persistence, which is linked to their perfluoroalkyl chain length. Molecules that are less heavily fluorinated can show very complex metabolic behavior, as is the case for fluorotelomer alcohols. These compounds are degraded via different but simultaneous pathways, which produce different stable metabolites. Biotransformation processes of PFC may occur when these compounds enter the environment, and thus known and unknown PFC may be generated in these compartments. Therefore, it is essential to determine metabolic pathways of such compounds in order to entirely understand their fate in the environment. This chapter summarizes methodological approaches and instmmental setups which have been implemented in biotransformation studies of PFC and focuses on mass spectrometric methods and the separation techniques coupled to the mass spectrometer (MS). Valuable MS approaches that have not been frequently used in studies on PFC are presented as well. Since compounds carrying C-F bonds exhibit unique properties, these will be initially presented to address the meaning of these properties both for analytical tasks and for the setup of biotransformation experiments. 

Well-known advantages of GC(-MS) over LC(-MS) are an unbeaten chromatographic resolution, which may be of importance for structural isomer separation, for example, for PFOS isomers [34], and less susceptibility to matrix effects. However, only a small fraction of PFC can be directly analyzed by GC methods, owing to the polar or even ionic structure of most of the PFC and their metabolites. Typical PFC that can be directly analyzed by GC are FTOH, fluorotelomer olefins, and other fluorotelomer-based compounds and metabolites [16]. However, the typical PFC such as PFCA and perfiuorosulfonic acids (PFSA) are non-volatile and therefore not suited for GC analysis. This can be circumvented by derivatiza-tion, for example, to the butyl [34] or i-propyl esters [35] of sulfonates or preparation of the anilides [36] or methyl esters [37] from PFCA. 

Ishibashi H, Ishida H, Matsuoka M et al (2007) Estrogenic effects of fluorotelomer alcohols for human estrogen receptor isoforms alpha and beta in vitro. Biol Pharm Bull 30(7) 1358-1359 Joensen UN, Bossi R, Leffers H et al (2009) Do perfluoroalkyl compounds impair human semen quality Environ Health Perspect 117(6) 923-927 Johansson N, Fredriksson A, Eriksson P (2008) Neonatal exposure to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) causes neurobehavioural defects in adult mice. Neurotoxicology 29(1) 160-169... 

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