Toward operationally reliable PFAS quantification in complex liver matrices: Systematic optimization of commercial...

A practical and robust sample preparation method was developed for the simultaneous quantification of 34 per- and polyfluoroalkyl substances (PFAS) in complex liver matrices by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cat (Felis silvestris catus) liver was used as the primary matrix for method optimization and validation. The final proposed method (Procedure 6), selected through systematic evaluation, consisted of alkaline digestion of 0.1 g freeze-dried tissue, hexane washing, and dual solid-phase extraction cleanup using Captiva EMR Food II and Strata PFAS cartridges. Procedure 6 achieved internal standard-corrected recoveries within 70-120% for almost all analytes, except for branched MeFOSAA (130%) and PFMBA (130%), although absolute recoveries for some PFAS were below 50%. The mean matrix effect was 12%, with individual values ranging from -43% to 49% (excluding FTSAs), indicating effective mitigation of ion suppression and enhancement. Both intra-batch and inter-batch coefficients of variation were below 15%, and method detection limits ranged from 0.0091 to 0.55 ng g^-1 dry weight for all target PFAS and from 0.013 to 0.35 ng g^-1 dry weight for major PFCAs and PFSAs. Applicability was further evaluated using common cormorant (Phalacrocorax carbo) liver and cat kidney and muscle samples, confirming reliable quantification across tissues with different matrix compositions and PFAS concentration ranges. Overall, the proposed method enables sensitive and reliable quantification of structurally diverse legacy and alternative/emerging PFAS in complex biological tissues using only 0.1 g of dry tissue.