Identification of Novel Perfluoroalkyl Ether Carboxylic Acids (PFECAs) and Sulfonic Acids (PFESAs) in Natural Waters Using Accurate Mass Time-of-Flight Mass Spectrometry (TOFMS)

Abstract

Recent scientific scrutiny and concerns over exposure, toxicity, and risk have led to international regulatory efforts resulting in the reduction or elimination of certain perfluorinated compounds from various products and waste streams. Some manufacturers have started producing shorter chain per- and polyfluorinated compounds to try to reduce the potential for bioaccumulation in humans and wildlife. Some of these new compounds contain central ether oxygens or other minor modifications of traditional perfluorinated structures. At present, there has been very limited information published on these "replacement chemistries" in the peer-reviewed literature. In this study we used a time-of-flight mass spectrometry detector (LC-ESI-TOFMS) to identify fluorinated compounds in natural waters collected from locations with historical perfluorinated compound contamination. Our workflow for discovery of chemicals included sequential sampling of surface water for identification of potential sources, nontargeted TOFMS analysis, molecular feature extraction (MFE) of samples, and evaluation of features unique to the sample with source inputs. Specifically, compounds were tentatively identified by (1) accurate mass determination of parent and/or related adducts and fragments from in-source collision-induced dissociation (CID), (2) in-depth evaluation of in-source adducts formed during analysis, and (3) confirmation with authentic standards when available. We observed groups of compounds in homologous series that differed by multiples of CF2 (m/z 49.9968) or CF2O (m/z 65.9917). Compounds in each series were chromatographically separated and had comparable fragments and adducts produced during analysis. We detected 12 novel perfluoroalkyl ether carboxylic and sulfonic acids in surface water in North Carolina, USA using this approach. A key piece of evidence was the discovery of accurate mass in-source n-mer formation (H(+) and Na(+)) differing by m/z 21.9819, corresponding to the mass difference between the protonated and sodiated dimers.

Mass defect filtering for suspect screening of halogenated environmental chemicals: A case study of chlorinated organophosphate flame retardants

“…Only molecular features with scores above 75% were investigated further through database searching and compound evaluation. The usual workflow involved generation of LC/QqTOF MS spectra and processing, application of advanced QqTOF MS filtering tools, visual inspection of detected peaks, and compound identification with databases and/or compound confirmation with authentic standards, if available commercially . In the following sections, we will refer to Figure and the specific step in the process to which we are referring.…”

“…A diagram of the workflow used for identifying known Cl-PFRs and the products of hydrolysis and transformation in the OP study mixture is shown in Figure 1 48,54 In the following sections, we will refer to Figure 1 and the specific step in the process to which we are referring. QqTOF MS (MS/MS or MS 2 ) product ion spectra of qualified precursor ions from the preceding MS-only spectrum.…”

“…MDF uses an input range of possible mass defects to filter ions and compounds whose mass defect shifts are within the set limit and remain close to the known chemical compound or class of interest. MDF has been used in other applications for the identification of phthalate metabolites in human urine, insecticide metabolites in human serum and urine, cytochrome p450 mediated metabolites in human liver microsomes and plasma, pesticides in vegetables, synthetic cannabinoids in herbal products, and perfluorinated compounds in various matrices such as human sera, fish, natural waters, end‐user products, and industrial blends and food contact material extracts, etc. LC/QqTOF mass spectrometry was used to screen for organophosphate compounds in sludge and aqueous solutions, but MDF was not applied in these studies.…”

Coupled production and emission of short chain perfluoroalkyl acids from a fast developing fluorochemical industry: Evidence from yearly and seasonal monitoring in Daling River Basin, China

“…Known fluorinated alternatives including short chain PFAAs and perfluoroether carboxylic and sulfonic acids (PFECAs and PFESAs) can adequately replace most C8 and higher homologue uses in many fluoropolymer applications. Although they are less persistent in the biota than the long chain PFASs, they are of concern because they do not break down in the environment and may cause similar toxicological effects as the long chain PFASs (Wang et al, 2013;Scheringer et al, 2014;Blum et al, 2015;Strynar et al, 2015). However, the consequences of the increased production and emission of short chain PFAAs are still largely unknown.…”

The Concept of Essential Use for Determining When Uses of PFASs Can Be Phased Out

“…Research at one fluorochemical production site in Bladen County, North Carolina has documented that Nafionrelated wastes have been released into the nearby Cape Fear River since at least 2012. 81 Moreover, the relatively advanced drinking water treatment plant in the city of Wilmington, North…”