Magnetic amino-functionalized metal-organic frameworks as a novel solid support in ionic liquids-based effervescent tablets for efficient extraction of polycyclic aromatic hydrocarbons in milks.

Herein, a kind of novel multi-layer core-shell nanocomposites (NSPN) was prepared by employing SiO and polyvinylpyrrolidone (PVP) polymers as modifiers and amino-functionalized metal-organic frameworks (NH-MIL101(Fe)) as coating. It was referred to as the NSPN and ILs-based effervescence-assisted dispersive solid-phase microextraction, hereafter abbreviated as NIE-DSM. In terms of extraction efficiency, SiO and PVP as modifiers and NH-MIL(Fe) as coating onto the surface of NiFeO cores played a synergistically enhancing effect on adsorption/extraction. Effervescent tablets were prepared by integrating the NSPN magnetic nanoparticles as adsorbents with imidazolium-based ionic liquids (ILs) as extractants as well as acidic and alkaline sources. Under vigorous dispersion of CO bubbles, the NIE-DSM method realized the goal of rapidly diffusing and separating the adsorbent/extractant (~3 min) without needing conventional vortexing or centrifugation step. Consequently, the NIE-DSM approach combined dispersion and adsorption/extractant in a synchronous way. Under optimized conditions, the NIE-DSM/HPLC-FLD method gave low limits of detection (0.008-0.034 μg kg) and satisfactory extraction recoveries (74.1-101.6%) for five polycyclic aromatic hydrocarbons (PAHs; fluorene, anthracene, pyrene, chrysene and benzo(a)pyrene) in milk samples. The intra-day and inter-day precision, expressed as relative standard deviations, was < 5.9% and 6.5%, respectively, demonstrating a high precision. Owing to no requirement for electrical power, this method shows great potential for outdoor monitoring of trace-level PAHs in food matrices.