Determination of 49 Perfluoroalkyl and Polyfluoroalkyl Substances in Human Serum by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

The healthy human serum sample (50 μL) was taken and placed in a 1.5 mL-centrifuge tube. 200 μL of 3.125 μg·L⁻¹ mixed internal standard solution was added,and the solution was vortexed for 60 s and sonicated at 4 ℃ for 10 min. The mixture was frozen at −20 ℃ for 1 h and centrifuged for 15 min at 4 ℃. 100 μL of supernatant was taken and placed in a 1.5 mL-centrifuge tube containing 150 μL of water,and the solution was vortexed for 60 s, sonicated for 5 min and centrifuged for 10 min at 4 ℃. 49 perfluoroalkyl and polyfluoroalkyl substances (PFASs) in the supernatant were determined by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Poroshell 120 EC-C₁₈ column was used as the stationary phase and the mixed solution composed of 4 mmol·L⁻¹ ammonium formate solution and acetonitrile at different volume ratios was used as the mobile phase for gradient elution. Electrospray ion (ESI) source was used for mass spectrometry. The targets were analyzed by multiple reaction monitoring (MRM) mode in negative ion (ESI⁻) scanning mode. As shown by the results, linear relationships between values of the mass concentration ratio and the peak area ratio of the 49 PFASs to internal standard were kept in definite ranges, with detection limits (3S/N) in the range of 0.000 2-0.166 7 μg·L⁻¹. Test for recovery was made by the standard addition method, giving results in the range of 80.5%-118%, with RSDs (n=6) of the determined values in the range of 0.80%-12%. This method was used for the analysis of 200 healthy human serum samples, and 49 PFASs were detected. Among them, the top five PFASs with medians of detection amounts were perfluorooctane sulfonic acid, 9-chloroperfluorotrioxynonanesulfonic acid, perfluorohexane sulfonic acid, perfluorooctanoic acid, and perfluorodecanoic acid, with medians of detection amounts of 107.188, 68.838, 51.810, 44.381, and 12.507 μg·L⁻¹, respectively.