Mechanistic studies in biodegradation of the new synthesized fluorosurfactant 9-[4-(trifluoromethyl)phenoxy]nonane-1-sulfonate

As a new potentially mineralizable fluorinated surfactant, 9-[4-(trifluoromethyl)phenoxy]nonane-1-sulfonate was synthesized and exposed to a standardized Zahn–Wellens test (OECD 302B). After the release of fluoride indicating the mineralization of the trifluoromethyl group, 9-[4-(trifluoromethyl)phenoxy]nonane-1-sulfonate was subjected to a further biodegradation test carried out in a fixed bed bioreactor (FBBR). Evolution of biodegradation routes and pursuit was done by quadrupole linear ion trap mass spectrometer (QqLIT-MS) and quadrupole time-of-flight tandem mass spectrometer (QqTOF-MS). Biotransformation was initiated via hydroxylation in the alkyl chain at different positions. Hydroxy-9-[4-(trifluoromethyl)phenoxy]nonane-1-sulfonate was further oxidized with subsequent scission of the molecule forming mainly p-(trifluoromethyl)phenolate, which was mineralized releasing inorganic fluoride. These results demonstrate, that the new synthesized fluorosurfactant 9-[4-(trifluoromethyl)phenoxy]nonane-1-sulfonate is completely biotransformed. However, some intermediates, depending on the position of hydroxylation, impede further mineralization.