Modifying of magnetic UiO-66-NH2 as a new nanosorbent by thermo-alkali-hydrolysis technology for highly efficient enrichment and determination of quercetin in apple peel

For rapid separation of quercetin from apple peel, a novel magnetic nanomaterial was prepared by a simple and economical thermal alkaline hydrolysis method in this work. This magnetic nanomaterial was obtained by mixing magUiO-66-NH2 (magnetic University of Oslo 66-NH2) with 0.05 mol·L-1 KOH aqueous solution and then heated, and was named magUiO-66-NH2-MH0.05 (magUiO-66-NH2-mixed heating0.05), which has better magnetic properties, thermal stability, pore capacity and average pore size than magUiO-66-NH2. The obtained magUiO-66-NH2-MH0.05 had strong adsorption capacity for quercetin, and the maximum adsorption capacity was 65.30 mg·g−1. MagUiO-66-NH2-MH0.05 tends to be monolayer-layer adsorption for quercetin, and electron sharing or transfer may occur during the adsorption process. Compared with naringenin, naringin and gallic acid, magUiO-66-NH2-MH0.05 showed good recognition ability for quercetin, and the recoveries were good. After 7 cycles, the adsorption capacity of magUiO-66-NH2-MH0.05 for quercetin was 96.3 % of the initial adsorption capacity. A magnetic solid-phase extraction method coupled with High-Performance Liquid Chromatography based on magUiO-66-NH2-MH0.05 was successfully used for rapid separation and determination of quercetin in apple peel. This study will help to discover the experimental law of the treatment of UiO-66-NH2 nanomaterials by hot alkaline hydrolysis, reveal the reaction mechanism, and expand the application of UiO-66-NH2 nanomaterials in food analysis.