Hydrothermal synthesis of functionalized magnetic MIL-101 for magnetic enrichment of estrogens in environmental water samples

Abstract

A simple hydrofluoric acid-free one-pot method was developed for the preparation of three functionalized magnetic MIL-101 composites (Fe₃O₄–NH₂@MIL-101, Fe₃O₄–COOH@MIL-101 and Fe₃O₄/C@MIL-101). As magnetic solid-phase extraction materials, they exhibited a remarkable preconcentration ability for estrone (E1), 17β-estradiol (E2), estriol (E3) and bisphenol-A (BPA). However, because the incorporated magnetic particles were decorated with different surface functional groups, the three magnetic MIL-101 composites exhibited certain differences in extraction efficiency of the four target estrogens. Herein, the Fe₃O₄–NH₂@MIL-101 composite as an adsorbent was applied for magnetic solid-extraction coupled with high performance liquid chromatography (HPLC) to determine the estrogens content in aqueous samples. The dominant parameters affecting enrichment efficiency including extraction time, sample pH, extraction temperature and desorption conditions were investigated. Under the optimized conditions, the developed method showed good linearity within the range of 0.2–100 μg L⁻¹, low detection limits (0.06–0.22 μg L⁻¹) and high repeatability (RSD, 5.9–8.3%). The recoveries were between 80.6 and 99.6% with the spiked level of 10 μg L⁻¹. The proposed method was successfully applied to determine the estrogens content in real water samples.