Aerobic Soil Biotransformation of 6:2 Fluorotelomer Iodide

摘要

6:2 FTI [F(CF_2)_6CH_2CH_2I] is a principal industrial raw material used to manufacture 6:2 FTOH [F(CF_2)_6CH_2CH_2OH] and 6:2 FTOH-based products and could enter aerobic environments from possible industrial emissions where it is manufactured. This is the first study to assess 6:2 FTI aerobic soil biotransformation, quantify transformation products, and elucidate its biotransformation pathways. 6:2 FTI biotransformation led to 6:2 FTOH as a key intermediate, which was subsequently biotransformed to other significant transformation products, including PFPeA [F-(CF_2)_4COOH, 20 mol % at day 91], 5:3 acid [F-(CF_2)_5CH_2CH_2COOH, 16 mol %], PFHxA [F(CF_2)_5COOH, 3.8 mol 96], and 4:3 acid [F(CF_2)_4CH_2CH_2COOH, 3.0 mol %]. 6:2 FTI biotransformation also led to a significant level of PFHpA [F(CF_2)_6COOH, 16 mol % at day 91], perhaps via another putative intermediate, 6:2 FTUI [F(CF_2)_6CH=CHI], whose molecular identity and further biotransformation were not verified because of the lack of an authentic standard. Total recovery of the aforementioned per- and polyfluorocarboxylates accounted for 59 mol % of initially applied 6:2 FTI by day 91, in comparison to 56 mol % when soil was dosed with 6:2 FTOH, which did not lead to PFHpA. Thus, were 6:2 FTI to be released from its manufacture and undergo soil microbial biotransformation, it could form PFPeA, PFHpA, PFHxA, 5:3 acid, and 4:3 acid in the environment.