An automated high-throughput SPE micro-elution method for perfluoroalkyl substances in human serum

An automated high-throughput solid phase extraction (SPE) micro-elution method for 8 perfluorosulfonic acids, 11 perfluorocarboxylic acids and fluorooctane sulfonamide in human serum was developed. Importance was attached to the application of small volumes of reagents and solvents in addition to low sample volumes (50 μL) in order to save the highly valuable sample material for follow-up and other studies. Instrumental analysis was performed by ultra high pressure liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-MS/MS). The recoveries of perfluoroalkyl substances (PFASs) were satisfactory and between 70 and 120% for most of the compounds at the three investigated spike concentrations. Perfluorobutane sulfonate (PFBS) was slightly underestimated at high concentrations (20 ng/mL; 67%), whereas perfluoropentanoate (PFPA), perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) were overestimated with 134, 131 and 133% respectively, at low spike concentrations (0.2 ng/mL). The precision of the method was below 20% coefficient of variation (CV%) for all target compounds with the only exception of PFOS (22%) at low spike concentrations. Method detection limits ranged from 0.006 to 0.34 ng/mL. High sensitivity, accuracy, repeatability and robustness have been demonstrated for an appropriate concentration range. The applicability for real samples was satisfactory demonstrated by analysis of 40 sera samples from the general population from Tromsø, Norway.