Amino-functionalized metal–organic frameworks for efficient solid-phase microextraction of perfluoroalkyl acids in environmental water

The ubiquitous occurrence of perfluoroalkyl acids (PFAAs) in environmental water has drawn much attention due to their high persistence and bioavailability. However, it is difficult for the traditional adsorbents to extract PFAAs because of their unique hydrophobic and oleophobic properties. In this study, an amino-functionalized ZIF-8 (NH2-ZIF-8) was fabricated and used as the coating materials of the solid-phase microextraction fiber for the determination of PFAAs in water samples. The introduction of the amino group improved the extraction performance of PFAAs via electrostatic interaction and hydrogen bond, which exhibited better extraction efficiencies than those of ZIF-8 coated fiber and commercial fibers. The extraction efficiencies of PFAAs decreased with the increase of pH values, indicating that electrostatic interaction between the carboxylic acid group of PFAAs and the amino group of NH2-ZIF-8 played a dominating role in enrichment. The fabricated fiber coupled with high-performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-MS/MS) was used for the detection of PFAAs in water samples, with a wide linear range (1–5000 ng L−1), low limits of detection (0.15–0.75 ng L−1), and good repeatability and reproducibility (1.9%-15.5%). The established method has been successfully applied in environmental water analysis, which provides a practical method for the determination of PFAAs in a convenient manner.