On-line solid phase extraction–ultra high performance liquid chromatography–quadrupole/Orbitrap high resolution mass spectrometry determination of per- and polyfluoroalkyl substances in human serum

• High-resolution mass spectrometry in parallel reaction monitoring mode was used to monitor per- and polyfluoroalkyl substances (PFAS) in human serum. • The targets of on-line solid-phase extraction were common linear PFAS and branched perfluorooctanesulfonate and perfluorooctanoic acid. • In human serum samples from China, br-perfluorooctanesulfonate accounted for approximately 30% of the ∑perfluorooctanesulfonate. • The results suggested high exposure to 6:2 chlorinated polyfluorinated ether sulfonate in the population.