Perfluorooctane carboxylic acid

The general structure of perfluorocarboxylic acids is F(CF2) cCOOH. Generally, PFCAs consist of 6 to 16 carbon atoms, where x = 5 to 15 (Table 3.1). Within this group of PFCAs, the most common is perfluorooctane carboxylic acid (PFOA, 8 carbon atoms). It should be noted, however, that trifluoroacetic acid (TFA, 1 carbon atom) is also a common and well-studied PFCA [2,3]. Similar to the PFSAs, the PFCAs also have small pAa values, typically 2-3 [4, 5] and are dissociated at environmental pH values ... 

Fluorinated surfactants have been commercially available since the 1950s. The first available were perfluoroalkyl sulfonates (e.g., perfluorooctane sulfonate, CgFisSOs, PFOS) and perfluoroalkyl carboxylic acids (e.g., perfluorooctanoic acid, C7F15COOH, PFOA) manufactured using the electrochemical fluorination (ECF) process [10]. The unique properties (e.g., surface tension lowering in aqueous systems, high chemical and thermal stability) of these acids and their derivatives when used at low concentrations resulted in their widespread use in industrial processes and consumer uses [11-13]. The most common commercially produced perfluorinated surfactants are the perfluoroalkyl acids (PFAAs) ... 

Perfluorinated organic compounds constitute a unique class of POP. They occur as completely fluorinated hydrocarbon derivatives, such as CF4, in the atmosphere, where they are regarded as atmospheric pollutants and potential greenhouse gases (see Chapter 7). Other perfluorinated compounds that are organic acids or their salts have been encountered as water pollutants. Most commonly cited are salts of perfluorooctane sulfonic acid others include salts of perfluorinated carboxylic acids, such as perfluorohexanoic acid ... 

Water and oil repellent finishes, normally perfluoroalkyl sulfonate (PFAS) and perfluorooctane sulfonate (PFOS), are not to be used, and their threshold limit is 1 pg/m each in the coated material whereas all other PFAS forms, the threshold limit is 20 pg/kg and MSDS is required to be supplied for verification. The test method is based on solvent extraction and GC-MS or HPLC-MS. For per fluoro carboxylic acids and salts (PFCA), the limiting value is 0.05 ppm or sum total is 0.1 ppm. 

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