Further Insight into Extractable (Organo)fluorine Mass Balance Analysis of Tap Water from Shanghai, China

Abstract

The ubiquitous occurrence of per-and polyfluoroalkyl substances (PFAS) and the detection of unexplained extractable organofluorine (EOF) in drinking water have raised growing concerns. A recent study reported the detection of inorganic fluorinated anions in German river systems, and therefore, in some samples, EOF may include some inorganic fluorinated anions. Thus, it might be more appropriate to use the term "extractable fluorine (EF) analysis" instead of the term EOF analysis. In this study, tap water samples (n = 39) from Shanghai were collected to assess the levels of EF/EOF, 35 target PFAS, two inorganic fluorinated anions (tetrafluoroborate (BF 4 − ) and hexafluorophosphate (PF 6 − )), and novel PFAS through suspect screening and potential oxidizable precursors through oxidative conversion. The results showed that ultra-short PFAS were the largest contributors to target PFAS, accounting for up to 97% of ΣPFAS.To the best of our knowledge, this was the first time that bis(trifluoromethanesulfonyl)imide (NTf 2 ) was reported in drinking water from China, and p-perfluorous nonenoxybenzenesulfonate (OBS) was also identified through suspect screening. Small amounts of precursors that can be oxidatively converted to PFCAs were noted after oxidative conversion. EF mass balance analysis revealed that target PFAS could only explain less than 36% of EF. However, the amounts of unexplained extractable fluorine were greatly reduced when BF 4 − and PF 6 − were included. These compounds further explained more than 44% of the EF, indicating the role of inorganic fluorinated anions in the mass balance analysis. KEYWORDS: extractable fluorine (EF), tetrafluoroborate (BF 4 − ), hexafluorophosphate (PF 6 − ), suspect screening, bis(trifluoromethanesulfonyl)imide (NTf 2 ), ultra-short PFAS

Lithium-ion battery components are at the nexus of sustainable energy and environmental release of per- and polyfluoroalkyl substances

“…Results of this study provide a clear indication that the impacts of manufacturing, use, and end-of-life management associated with infrastructure components such as LiBs require additional consideration along with other issues such as resource recovery. This includes environmental impacts associated with other fluorinated, but non-PFAS LiB electrolytes and detected in drinking water 21 and with metals (e.g., Cu, Al) used in LiB electrodes, cables, and battery packs 52 . Researchers are in the early stages of studying fluorine-free electrolytes 53 , and although promising, alternative materials also merit close evaluation of potential environmental and human health risks.…”

Water Analysis: Emerging Contaminants and Current Issues

“…Jiao et al used an extractable organic fluorine (EOF)/extractable fluorine (EF) method, along with measurement of 35 target PFAS and two inorganic fluorinated anions (BF 4 – and PF 6 – ) to provide insights into the mass balance of PFAS in tap water from Shanghai . Results revealed that ultrashort PFAS were the dominant contributors to target PFAS, accounting for up to 97% of the total.…”

Implications of grouping per‐ and polyfluoroalkyl substances for contaminated site regulation

“…Nonspecific aggregating approaches such as particle‐induced gamma emissions (PIGE) (Ritter et al, 2017), fluorine nuclear magnetic resonance (NMR) (Camdzic et al, 2023), EOF, and AOF (Kärrman et al, 2021), also suffer from limitations with none achieving all three requirements. Where inorganic fluorine is present in samples at high concentrations relative to PFAS, this may be difficult to account for, despite the development of extraction methods to improve this for EOF and AOF (Jiao et al, 2023; Kärrman et al, 2021). Organic fluorine not included in the definition (e.g., the pesticide 1080 and some pharmaceuticals) can also result in false positives.…”