A novel automated micro solid phase extraction (µSPE) method to quantify 21 per- and polyfluoroalkyl substances compounds in biological samples

A semi-automated micro solid-phase extraction (μSPE) method has been developed and optimized for the quantification of 21 per- and polyfluoroalkyl substances (PFAS) across various biological matrices, including plasma, serum, urine, and liver tissue. This method employed μSPE cartridges integrated with a PAL-RTC robotic system, which enabled precise flow control and high-throughput procedures while ensuring exceptional extraction efficiency and reproducibility. Sample homogenization of liver tissues was achieved by bead-mill technology which eliminated sample cross-contamination and significantly reduced processing time. The extraction efficiency was influenced by the concentration of methanol in the sample, especially for longer-chain PFAS (C9–14). Extraction efficiencies of over 90% extraction were achieved with loading solutions containing 50–60% methanol in plasma and serum, and up to 80% methanol in water samples. The μSPE protocol included two sequential wash steps that provided excellent matrix clean-up, and reduced background signals by over 95% compared to traditional protein precipitation (PP) methods. The µSPE-LC-MS/MS method offers high sensitivity (method detection limits between 0.008 ng/mL and 0.048 ng/mL), along with good recoveries (90.3 to 105.1%), and precision (RSD <10%). It also demonstrated strong agreement with non-certified values of NIST Standard Reference Materials (SRM 1957/1958). The method was successfully used in the analysis of PFAS in human urine and plasma, as well as in mouse liver samples from an in vivo study. The μSPE approach provides a sensitive, reproducible, and automated solution that requires limited biological sample volumes, making it suitable for the analysis of PFAS in biomonitoring and toxicokinetic studies.