Simultaneous Analysis of Ultrashort-Chain to Long-Chain (C1- C10) and Alternative Per-and Polyfluorinated Substances in Human Plasma and Serum

The per- and polyfluoroalkyl substances (PFAS) targeted for analysis in blood may vary based on the specific concern in a given region or population. Several studies have indicated a rapid increase in environmental concentration of USC PFAS, raising the concern of elevated human exposure. The measurement of USC PFAS in blood can not only monitor the human exposure but also provide a tool for studying the potential risks associated with USC PFAS exposure. An LC-MS/MS method was developed for the quantitation of C1 to C10 carboxylic acid and sulfonic acid PFAS. Chromatographic separation was achieved with the use of a mixed-mode LC column. The established method was then applied to measure PFAS in various human serum and plasma samples, including NIST SRM 1950 human plasma. The analytes in this study included C1 to C10 carboxylic acid and sulfonic acid PFAS along with four alternative compounds: hexafluoropropylene oxide dimer acid (HFPO-DA); 4,8-dioxa-3H-perfluoro-nonanoic acid; 9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid; and 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid. For method accuracy and precision testing, charcoal-stripped fetal bovine serum (FBS) was chosen due to its absence of C1 to C10 PFAS, except for TFA. Therefore, a TFA isotope, 13C-TFA, was implemented as a surrogate to test the method accuracy for TFA in the serum sample. Additionally, ten isotopes of C3 to C10 PFAS were added to the samples at 1 ppb to serve as extracted internal standards to verify the accuracy of the entire workflow. Calibration standards were prepared in reverse osmosis water due to its cleanliness for all analytes. Phosphate-buffered saline was incorporated into the calibration standard solution to obtain the similar chromatographic performance between standard and sample solutions. All analytes demonstrated satisfactory accuracy and precision, making it a suitable method for the quantitation of PFAS in serum.