National Environmental Monitoring Conference

LC-MS/MS methods for the analysis of short-chain (C4, C5) and
long-chain (>C5) per- and polyfluoroalkyl substances (PFASs) have
been well developed based on reversed-phase (RP) chromatography. It is
necessary to pair with an additional delay column to isolate the
interference generated from HPLC systems for low-level PFAS analysis
especially when direct injection methodology is adopted without sample
concentration procedure. With proper modification, these typical RP
methods can be applied to the analysis of emerging PFAS alternatives
such as GenX and ADONA, which are perfluoroalkyl ether carboxylic acids
(PFECAs) used as PFOA substitutes. These established LC methods,
however, may not be suitable for the analysis of newly trending
ultrashort-chain (C2, C3) PFASs mainly due to their insufficient
retention on typical RP columns.

While the use of short-chain
PFASs (PFBA and PFBS) is intentional, more and more studies have shown
the ubiquitous occurrence of C2 and C3 ultrashort-chain PFASs in aqueous
environmental samples. These include trifluoroacetic acid (TFA),
perfluoropropanoic acid (PFPrA), perfluoroethane sulfonate (PFEtS), and
perfluoropropane sulfonate (PFPrS). It was shown that PFPrA is the
predominant PFAS (up to 45% of total detectable PFASs) in the rain and
snow samples collected from USA, France, and Japan. To date, there are
not many studies showing the contamination sources and levels for these
ultrashort-chain PFASs. A recent study showed the detection of PFEtS and
PFPrS in aqueous film-forming foams (AFFFs) and ground waters from 11
military sites in the US, indicating AFFF firefighting foam may be one
of the sources of the ultrashort-chain PFASs.

This presentation
will discuss the LC-MS/MS method development for C2 and C3 PFASs
analysis and analytical methodologies for simultaneous chromatographic
determination of alternative and legacy PFASs.