Simultaneous Determination of Per- and Polyfluoroalkyl Substances and Bile Acids in Human Serum Using Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

There is evidence of a positive association between per- and polyfluoroalkyl substances (PFAS) and cholesterol levels in human plasma, which may be due to common reabsorption of PFAS and bile acids (BAs) in the gut. Here we report development and validation of a method that allows simultaneous, quantitative determination of PFAS and BAs in plasma, using 150 uL or 20 uL of sample. The method involves protein precipitation using 96-well plates. The instrumental analysis was performed with ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS), using reverse-phase chromatography, with the ion source operated in negative electrospray mode. The mass spectrometry analysis was carried out using multiple reaction monitoring mode. The method proved to be sensitive, robust and with sufficient linear range to allow reliable determination of both PFAS and BAs. The method detection limits were between 0.01 and 0.06 ng⋅mL-1 for PFAS and between 0.002 and 0.152 ng⋅mL-1 for BAs, with the exception of glycochenodeoxycholic acid (0.56 ng⋅mL-1). The PFAS measured showed excellent agreement with certified plasma PFAS concentrations in NIST SRM 1957 reference plasma. The method was tested on serum samples from 20 healthy individuals. In this proof-of-concept study, we identified significant associations between plasma PFAS and BA levels, which suggests that PFAS may alter the synthesis and/or uptake of BAs.