9-Plex ultra high performance liquid chromatography tandem mass spectrometry determination of free hydroxyl polycyclic aromatic hydrocarbons in human plasma and urine

•A series of multiplexed stable isotope mass tags (SIMTs) were firstly reported.•Nine real samples can be determined by a single UHPLC-MS/MS (MRM) run.•SIMT-346 labeled OH-PAHs standards were used as ISs for 9-plex quantitation.•The method has high-throughput, sensitivity, accuracy and ease-of-handling.