Navigating PFAS Analysis in Complex Matrices: The Role of Isotope Dilution.

Per- and Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation

Prepared by A. Sandy, E. Wang, R. Marfil-Vega, A. Owens
Shimadzu Scientific Instruments, 7102 Riverwood Drive, Columbia, Maryland, 21046, United States


Contact Information: [email protected]; 410-910-0869

ABSTRACT

Per- and polyfluoroalkyl substances (PFAS) have been linked to serious health effects. A Head-Space Solid Phase Microextraction - Triple Quadrupole Gas Chromatography/Mass Spectrometry (HS-SPME-GC/MS/MS) method has demonstrated its capability in complimenting LCMS methods for volatile PFAS analysis. To evaluate the method’s performance with complex aqueous matrices, bottled water and four juice samples were analyzed to assess potential matrix effect.
Thirteen volatile PFAS targets were analyzed. A laboratory control sample (LCS) was analyzed to determine the general performance of the method. Target compounds were spiked into the water samples, as well as into two brands of carton apple juice (Brands X and Y), one plastic bottled apple juice (Brand X), and a berry blend carton juice (Brand X).
No significant matrix effects were observed in bottled water. However, initial investigation of the juices revealed matrix effects. For the same flavored juice packaged differently, some compounds, such as 6:2 FTAC, showed no matrix effects, while others, such as MeFOSA, was significantly affected. In the boxed juice, MEFOSA recovery was enhanced, while in the plastic bottle from the same brand, recovery was suppressed. It was also noted that even PFAS within the same chemical class responds differently in different aqueous matrices exposed to various materials.
ETFOSA highlighted the necessity of isotope dilution. For this compound, the peak area doubled in the paper box compared to LCS sample. However, the internal standard area also doubled, compensating for matrix enhancement. Subsequent analysis using an isotope dilution method resulted in most compounds achieving mean percent recovery within 60-140%, and %RSD was < 15% for all compounds. Compounds lacking commercially available internal standard showed recoveries below method criteria. This study illustrated the variable behavior of same class of PFAS in complex aqueous matrices of the same type and demonstrated the necessity of isotope dilution for this analysis.