Magnetic solid-phase extraction based on sulfur-functionalized magnetic metal-organic frameworks for the determination of methylmercury and inorganic mercury in water and fish samples

A novel magnetic metal-organic frameworks (Fe3O4@UiO-66-SH) was successfully prepared by coating Fe3O4 nanospheres with sulfur-functionalized UiO-66. The Fe3O4@UiO-66-SH possesses both the mag-netic properties of Fe3O4 and the diverse properties of metal-organic framework (MOF) in one ma-terial, which has the superiority of high surface area, easy-operation and strong adsorb ability with mercury, is used for the magnetic solid-phase extraction of methylmercury (MeHg+) and inorganic mercury (Hg2+) in water and fish samples. The analyzes were conducted by high performance liq-uid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The different pre-treatment conditions influencing the extraction recoveries of Hg2+ and MeHg+, including adsorbent amount, pH, extraction time, elution solvent, elution volume, desorption time, co-existing ions and dissolved organic materials were investigated. Under the optimized conditions, the limits of detection (LODs) of Hg2+ and MeHg+ for water samples were 1.4 and 2.6 ng L-1, and the limits of quantifi-cation (LOQs) of Hg2+ and MeHg+ for water samples were 4.7 and 8.7 ng L-1. The enrichment fac-tors (EFs) were 45.7 and 47.6 fold for Hg2+ and MeHg+, respectively. The accuracy of the proposed method was demonstrated by analyzing the certified reference material of fish tissue (GBW10029) and by determining the analyte content in spiked water and fish samples. The determined values were in good agreement with the certified values and the recoveries for the spiked samples were in the range of 84.5-96.8%. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A novel magnetic metal-organic framework (Fe3O4@UiO-66-SH) was prepared for the magnetic solid-phase extraction of mercury in water and fish samples. Under optimized conditions, the method showed effective determination of Hg2+ and MeHg+ in water samples, with good agreement between determined values and certified values, and high recoveries in spiked water and fish samples.