A magnetic-based dispersive micro-solid-phase extraction method using the metal-organic framework HKUST-1 and ultra-high-performance liquid chromatography with fluorescence detection for determining polycyclic aromatic hydrocarbons in waters and fruit tea

• The composite MOF HKUST-1 + Fe3O4 MNPs is prepared by simple mixing.
• The material (25 mg) is used in a magnetic-assisted extraction method and UHPLC-FD.
• The composite was a suitable sorbent for PAHs in waters and fruit tea infusions.
• The overall M-d-μSPE-UHPLC-FD method was optimized and validated.
• LODs ∼low ng L−1 were obtained for heavy PAHs only requiring 20 mL of sample.

A hybrid material composed by the metal-organic framework (MOF) HKUST-1 and Fe3O4 magnetic nanoparticles (MNPs) has been synthetized in a quite simple manner, characterized, and used in a magnetic-assisted dispersive micro-solid-phase extraction (M-d-μSPE) method in combination with ultra-high-performance liquid chromatography (UHPLC) and fluorescence detection (FD). The application was devoted to the determination of 8 heavy polycyclic aromatic hydrocarbons (PAHs) in different aqueous samples, specifically tap water, wastewaters, and fruit tea infusion samples. The overall M-d-μSPE-UHPLC-FD method was optimized and validated. The method is characterized by: its simplicity in both the preparation of the hybrid material (simple mixing) and the magnetic-assisted approach (∼10 min extraction time), the use of low sorbent amounts (20 mg of HKUST-1 and 5 mg of Fe3O4 MNPs), and the low organic solvent consumption in the overall M-d-μSPE-UHPLC-FD method (1.5 mL of acetonitrile in the M-d-μSPE method and 2.8 mL of acetonitrile in the UHPLC-FD run). The resulting method has high sensitivity, with LODs down to 0.8 ng L−1; adequate intermediate precision, with relative standard deviation values (RSD) always lower than 6.3% (being the range 5.9–9.0% in tap water for a spiked level of 45 ng L−1, 6.1–14% in wastewaters for a spiked level of 45 ng L−1, and 7.2–17% in fruit tea infusion samples for a spiked level of 45 ng L−1); and adequate relative recoveries, with average values of 82% in tap water, and 94% and 75% in wastewater and fruit tea infusion samples, respectively, if using the proper matrix-matched calibration.