[Industry report] PFAS Non-targeted Analysis And Methods Interim Report
By The Chemours Company FC, LLC
September 15, 2020
This report has been prepared by The Chemours Company FC, LLC (Chemours) to provide an update on the characterization of previously unidentified (additional) per- and polyfluoroalkyl substances (PFAS) in aqueous samples collected from process wastewater, non-process wastewater (i.e., non-contact cooling water [NCCW]) and stormwater at the Chemours Fayetteville Works, North Carolina site (the Facility; Figure 1). The purpose of the work is to identify previously unknown PFAS that may be present in samples of collected water and to develop standards and methods to facilitate the quantitative analysis of these PFAS. The work described in this report was conducted according to the PFAS Non-Targeted Analysis and Methods Development Plan, Version 2 (the Development Plan, Chemours and Geosyntec, 2019). This work is intended to address requirements specified in Paragraph 11 subpart (a) in the Consent Order executed 25 February 2019 between Chemours and the North Carolina Department of Environmental Quality (DEQ) with the Cape Fear River Watch (CFRW) as intervenor. Other parts of the Consent Order will be addressed separately by Chemours.
Non-targeted analysis refers to a procedure that searches for unknown compounds in a sample following analysis of the sample by a given analytical method; the compounds are considered to be unknown because the analytical method has not been calibrated for them (for example, because authentic standards do not exist). Analytical methods do, however, contain data (such as mass spectral data) that can be used to provide some information on unknown compounds despite the lack of calibration.
Non-targeted analysis for unknown PFAS can be conducted using liquid chromatography coupled to high resolution quadrupole time of flight mass spectrometry (Q-TOF-MS). Q-TOF-MS accurately measures the mass-to-charge ratio of unknown PFAS facilitating the determination of their chemical formulas. Relevant structural information can then be interpreted by fragmenting ions via tandem mass spectrometry, where candidates that do not fit the fragmentation requirements for a particular structure are eliminated so that the tentative structure for the molecule can be assigned. After tentative identification, the structural identity of an analyte can be further assessed by comparing the analyte’s chromatographic retention time and mass spectrometry fragmentation patterns to those of an authentic standard.
View report here.