Four water stable metal-organic frameworks (MOFs), MIL-101(Cr), MIL-100(Fe), MIL-53(Al), and UiO-66(Zr), were used as adsorbents for concentration of four androgens and progestogens from water. The adsorption abilities of target analytes on the four MOFs were investigated by experimental and molecular simulation strategies, and UiO-66(Zr) was ultimately selected as the sorbent to develop a porous membrane protected micro-solid-phase extraction (μ-SPE) method for simultaneous extraction androgens and progestogens in environmental water samples followed by LC-MS/MS detection. Several variables affecting the extraction efficiency were systematically investigated, including pH, salt concentration, extraction time, kind of desorption solvent, and desorption time. Under the optimized conditions, excellent linearity was obtained in the range of 20.32–2032 ng/L for T, 10.24–1024 ng/L for P, 7.624–762.4 ng/L for TP , and 8.376–837.6 ng/L for MPA . Limits of detection (LODs) and limits of quantification (LOQs) were 10 ng/L and 20 ng/L for T, 4.0 ng/L and 10 ng/L for P, 2.0 ng/L and 7.0 ng/L for TP, and 3.0 ng/L and 8.0 ng/L for MPA, respectively. The recoveries were ranged from 80.5% to 102.4%. Furthermore, the μ-SPE device could be used for at least 10 extractions (RSD < 10.0%). Meanwhile, comparison was made with solid-phase extraction, and the developed method was demonstrated to be a convenient and eco-friendly pretreatment method for water samples.
A surface imprinted polymer of type UiO-66-NH2@MIP was prepared by combining molecular imprinted polymers (MIPs) and an amino-functionalized zirconium-based metal-organic framework. Quercetin is used as the virtual template, UiO-66-NH 2 acts as the carrier to which the monomer acrylamide can be copolymerized. The material was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. It was used as a sorbent in a solid-phase extraction column. The extraction conditions were optimized. The adsorption capacities for aflatoxins AFB1, AFB2, AFG1 and AFG2 by this SPE and by the commercial SPE were compared. The method was successfully applied to quantify the aflatoxins in grain. Figures of merit include (a) good linearity (range from 0.20–45 μg·kg −1 ) with R 2 (range from 0.9986–0.9994), (b) low detection limits (90–130 ng·kg −1 ), (c) acceptable reproducibility (1.0–5.9%; for n = 6), and (d) relatively satisfactory recovery rates (74.3–98.6%). The new sorbent has good selectivity and reusability.
UiO-66-NH 2 @MIPs were synthesized with modified UIO-66-NH 2 as core and quercetin as pseudo template. A cartridge was prepared with the polymers as the sorbent, and its performance was compared with different commercial SPE cartridges.
Xuejin Mao,Aiping Yan,Yiqun Wan,Dongmei Luo,Hongshun Yang
A QuEChERS-type method without matrix interference was designed and developed to determine organophosphorus pesticide residues in edible vegetable oils, based on dispersive solid-phase extraction with cleanup using UiO-66 as sorbent. Microporous UiO-66 directly and selectively adsorbed organophosphorus pesticides and excluded interfering compounds. Clean analytes were obtained by elution and analyzed using gas chromatography–tandem mass spectrometry. The dispersive solid-phase extraction conditions (amount of adsorbent, extraction time, desorption solvent volume, and elution time) were optimized. The limits of detection of the pesticides in vegetable oils were 0.16–1.56 ng/g. Under optimized conditions, the average pesticide recoveries were 81.1–113.5%. The intraday and interday relative standard deviations for analyte recovery were <8.2 and <13.9%, respectively. Thus, the method is reliable and could detect organophosphorus pesticide residues in edible vegetable oils. Furthermore, UiO-66 can be easily recycled and reused at least 10 times, reducing the cost of analysis.
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