Detection and quantitation of PFAS compounds in human placental tissue using laminar flow tandem mass spectrometry
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Abstract
Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic compounds used in manufacturing, including food packaging, cookware, clothing, and cosmetics. PFAS are water- and oil-resistant and thermally stable. As a result, these compounds persist in the environment and can bioaccumulate in the body. PFAS have been detected in multiple tissues, including, blood serum, urine, breastmilk, and placental tissue, and are associated with negative effects on human health, including high blood pressure and pre-eclampsia in pregnant women, low infant birth weight, decreased immune responses, increased risk of some cancers, hormonal effects, and increased cholesterol levels.
The objective of this research was to evaluate the use of laminar flow tandem mass spectrometry following solid-phase extraction (SPE) using weak anion exchange (WAX) properties for the detection and quantitation of PFAS compounds in human placental tissue. The eleven analytes examined in this study were perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), and perfluorododecanoic acid (PFDoA).
This study used a seven-point calibration curve made using certified reference materials (Wellington Laboratories, Ontario, CA) and examined calibration curves in solvent and matrix-matched calibration curves. All samples were prepared by spiking certified reference material (Wellington) into homogenized placental tissue. The concentration of each PFAS analyte varied due to slightly different concentrations within the standard solution. Sample preparation consisted of homogenization of human placental tissue using the Bead Ruptor Elite Bead Mill Homogenizer (Omni), followed by extraction with a WAX SPE column (UCT, ECWAX053). All samples then underwent nitrogen evaporation to dryness and reconstitution and analyzed with a laminar flow Qsight ultra-high pressure liquid chromatography-tandem mass spectrometer (LC-MS/MS, PerkinElmer, Waltham, MA, USA). The instrument was equipped with a Selectra C18 column with a Brownlee C18 delay column. Two recovery experiments were also performed to evaluate possible sources of analyte loss. Comparison of the recovery rates of PFAS analytes in pre-extraction spiking, post-extraction spiking, blank placental matrix was used to determine whether analyte loss may have occurred due to placental matrix effects or due to the SPE sample preparation process. Post-column infusion evaluated the possibility of ion suppression due to co-eluting compounds within the placental matrix.
PFAS analytes were quantitated at concentrations as low as 5ng/mL in the matrix-matched calibration curve, and the eleven analytes showed an acceptable bias of ±10%. Considering the injection volume of 10uL, this concentration corresponds to an on-column mass of 50pg. The recovery rate of PFAS compounds varied greatly between individuals and analytes, which ranged from 12.97% to 102.18%. Two recovery studies, post-extraction spiking and post-column infusion, show that matrix effects and the SPE sample preparation process both contributed to analyte loss, but each analyte is impacted by these two factors to a different extent.The ability to efficiently and accurately quantitate PFAS compounds within placental tissue will allow for better understanding of the toxicity of PFAS compounds towards reproductive health.