Simultaneous determination of perfluorooctanoic acid and perfluorooctanesulfonic acid in Korean sera using LC-MS/MS

Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are synthetic chemicals that have been used in various industries and household products. These can easily accumulate in the human body, causing adverse effects on human health. In this study, a high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous analysis of PFOA and linear PFOS in human serum. Owing to a lack of PFOA- and PFOS-free human serum, ¹³C₈-PFOA and ¹³C₈-PFOS were used as surrogate analytes for quantification. A sensitive and selective sample preparation method was developed and optimized by combining solid-phase extraction and protein precipitation method. The lower limit of quantification was 0.05 ng/mL, and the analytical response was linear up to 10 ng/mL for both PFOA and linear PFOS. Chromatographic separation of the linear PFOS from branched isomers was achieved within 5.5 min. The method was validated at various concentrations and afforded acceptable accuracy and precision values. After validation, the method was successfully applied to evaluate the exposure levels of PFOA and linear PFOS in the Korean population. The serum concentrations of PFOA and linear PFOS were 0.42-28.3 ng/mL and 0.81-57.6 ng/mL, respectively. The median concentration of linear PFOS was approximately 2.6-fold higher than that of PFOA. The concentration of PFOA was higher in women than men (p < 0.05) and that of linear PFOS was not significantly different between men and women. Therefore, a sensitive, selective, and reliable bioanalytical method was developed and validated. This method can potentially be applied to biomonitoring studies involving PFOA and linear PFOS.