Dan Wei,Ao Pan,Can Zhang,Ming Guo,Chaoyan Lou,Ju Zhang,Huizhen Wu,Xu Wang
A simple, rapid and sensitive vortex-assisted magnetic solid phase extraction (MSPE) method using core–shell structured magnetic covalent organic frameworks (Fe 3 O 4 /COF-TpBD) as adsorbents was established for simultaneous determination of aflatoxins, ochratoxins and enniatins in maize before high-performance chromatography tandem spectrometry detection. Fe 3 O 4 /COF-TpBD was facilely fabricated, characterized, and applied for simultaneous extraction of ten mycotoxins from maize. Key parameters affecting MSPE efficiency were investigated. The method possessed good linearity (0.05–50 μg/kg), high sensitivity (0.02–1.67 µg/kg for limits of detection), and satisfactory recoveries (73.8–105.3 %), with relative standard deviations less than 8.5 %. The amount of adsorbent used (5 mg) and the time required (0.5 min each for adsorption and for desorption) for MSPE were greatly shortened in comparison with the previous reports. Therefore, the fabricated Fe 3 O 4 /COF-TpBD exhibited a great potential for rapid extraction of common mycotoxins in maize, which can be attributed to its multiple interactions with the target mycotoxins.
Most of the reported covalent organic frameworks (COFs) are hydrophobic, limiting their adsorption application in sample pretreatment field. In this work, sulphonate functionalized magnetic covalent organic frameworks (COFs) composites were first synthesized by loading gold nanoparticles on Fe 3 O 4 @COF(TpBD) surface and then functionalized by sodium 3-mercaptopropanesulphonate immobilization via Au-S bonding formation (denoted as Fe 3 O 4 @COF(TpBD)@Au-MPS nanocomposites), which were further utilized as adsorbents for magnetic solid-phase extraction (MSPE) of fluoroquinolones. Compared with Fe 3 O 4 @COF(TpBD), the composites exhibited higher affinity to fluoroquinolones. Under optimized conditions, the developed MSPE method coupled with HPLC–MS/MS showed good linearity (R 2 ≥0.9989) and yielded low limits of detection (0.1–1.0 μg kg− 1 ) for fluoroquinolones. Moreover, the proposed method was successfully applied to extract fluoroquinolones from spiked meats (pork, chicken and bovine). The satisfactory recoveries were in the range of 82–110.2% with the relative standard deviations (RSDs) lower than 7.7%. These results indicated that the Fe 3 O 4 @COF(TpBD)@Au-MPS is a promising magnetic adsorbent for trace fluoroquinolones determination in meat samples. This work not only provided a facile strategy for COF functionalization, but also developed an efficient method for detecting fluoroquinolones in foodstuffs.
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