Facile mechanochemistry synthesis of magnetic covalent organic framework composites for efficient extraction of microcystins in lake water samples.

Easy-preparation magnetic solid-phase extraction (MSPE) adsorbents with excellent extraction performance are very indispensable for MSPE techniques. Herein, a magnetic carbon nanotube covalent organic framework composite (MCNTs@TpPa-1) was prepared simply and rapidly through mechanochemical synthesis as MSPE adsorbent for enriching microcystins (MCs). The synthesized MCNTs@TpPa-1 exhibited well water dispersibility, high affinity with MCs and large surface area, resulting in outstanding extraction performance for MCs. Subsequently, combined with high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), an efficient, sensitive and convenient MSPE method was set up for the determination of trace MCs from aqueous sample, which exhibited acceptable repeatability (RSDs (relative standard deviations) ≤ 6.8%, n = 6), low limits of detection (LODs, 0.8-1.5 pg mL), reliable linearity (R ≥ 0.9991) and broad range of linearity (2.0-1000 pg mL). Furthermore, the developed method was applied to lake samples and trace MCs (9.6-24.6 pg mL) were found with satisfactory recovery (85.0-106.0%). The results indicated powerfully MCNTs@TpPa-1 was of significant potential as an MSPE sorbent for detection of trace MCs in water. Moreover, considering the complexity of traditional preparation methods, novel prospects for preparing magnetic covalent organic frameworks (COFs) with excellent extraction properties were opened up.