The metal–organic framework PCN-250 for the extraction of endocrine disrupting compounds in human urine by stir bar sorptive dispersive microextraction

Abstract

An analytical method based on stir bar sorptive dispersive microextraction (SBSDME), followed by liquid chromatography coupled to tandem mass spectrometry detection (LC-MS/MS), has been satisfactorily developed for the determination of twelve endocrine disrupting compounds (EDCs), bisphenols and benzophenones, in urine samples. The PCN-250(Fe2Mn) metal–organic framework (MOF) has been used as effective sorbent in the method, while later involving cobalt ferrite (CoFe2O4) magnetic nanoparticles to speed up the magnetic retrieval, without the need of preparing any complex composite. The extraction capacity of the PCN-250(Fe2Mn) and its compatibility with the CoFe2O4 magnetic nanoparticles were compared with other conventional MOFs (i.e., MIL-101(Fe)–NH2, CIM-80(Al), and UiO-66(Zr)) in order to select the most adequate sorbent. The quantitative parameters affecting the SBSDME process (i.e., sorbent amount, extraction and desorption times, and ionic strength) were optimized by using a Box-Behnken experimental design. Under the optimized conditions, the proposed method was properly validated, showing good linearity (at least up to 20 μg L−1), enrichment factors ranging from 9 to 125, limits of detection in the ng/L range (1.5 – 53 ng L−1), and good intra- and inter- day precision (relative standard deviations below 15 %). Matrix effects were observed for the direct urine analysis, but they were negligible when a 1:5 (v/v) dilution with ultrapure water was performed. Finally, the method was successfully applied to human urine samples from three volunteers, obtaining quantitative relative recoveries (82 – 118 %). This work exploits, for the first time, the high potential that PCN-250(Fe2Mn) exhibits when it is used as sorbent for microextraction purposes.