Trace analysis of per- and polyfluorinated alkyl substances (PFAS) in dried blood spots-Demonstration of reproducibility and comparability to venous blood samples

Per-and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that have been widely used in con-sumer, personal care, and household products for their stain-and water-repellent properties. PFAS exposure has been linked to various adverse health outcomes. Such exposure has commonly been evaluated in venous blood sam-ples. While this sample type can be obtained from healthy adults, a less invasive method of blood collection is required when evaluating vulnerable populations. Dried blood spots (DBS) have gained attention as a biomatrix for exposure assessment given the relative ease of collection, transport, and storage. The objective of this study was to develop and validate an analytical method to measure PFAS in DBS. A workflow is presented for extracting PFAS from DBS, chemical analysis by liquid chromatography-high resolution mass spectrometry, normalization for blood mass, and blank correction to account for potential contamination. Over 80 % recovery was achieved for the 22 PFAS measured with an average coefficient of variation of 14 %. Comparison of PFAS concentrations detected in DBS and paired whole blood samples from six healthy adults was correlated (R2 > 0.9). Findings demonstrate trace levels of a broad range of PFAS in DBS can be reproducibly measured and are comparable to liquid whole blood samples. DBS can offer novel insights to environmental exposures, including during critical windows of susceptibility (i.e., in utero, early life), which have been largely uncharacterized.