Core-shell magnetic covalent organic framework nanocomposites as an adsorbent for effervescent reaction-enhanced microextraction of endocrine disruptors in liquid matrices

Abstract

For the first time, a kind of novel magnetic covalent organic framework nanocomposites (NiFe2O4@COFs) was fabricated through facile room-temperature synthesis approach. The magnetic nanocomposites (MNCs) were based on NiFe2O4 as magnetic core and COFs as shell. The NiFe2O4@COF MNCs were used for the first time as an adsorbent/extractant in the effervescent reaction-enhanced microextraction (MNER-EM) procedures. The equilibrium adsorption capacities (Qe, mg/g) of six endocrine disruptors (EDs) on the MNCs reached up to 38.3–88.1 mg/g, which mainly resulted from strong π-π interactions between EDs and NiFe2O4@COF MNCs. The MNER-EM method integrated efficiently MNCs-based adsorption/extraction, CO2-induced vigorous dispersion and conveniently magnetic separation into one synchronous step. Several operational parameters were rigorously optimized, including molar ratio of effervescent tablet composition, kind and dosage of adsorbent, kind of elution solvent, pH, extraction temperature and salt addition. Under optimized conditions, the MNER-EM/HPLC-FLD method had a good linear range (0.1 ~ 0.5–200 µg L−1), good recoveries (83.4–106.2%), low limits of detection (0.019–0.096 µg L−1) and high precision (RSDs of 3.11–5.73%) for six EDs in real-world water, beverage and human urine and serum samples. Consequently, the NiFe2O4@COF MNCs provide a good alternative for replacing traditional magnetic separation and adsorbent materials, and also this proposed method shows a great potential in conventional monitoring of trace EDs in liquid matrices.