原位溶剂热聚合法制备金属有机骨架/碳化氮纳米片涂覆的固相微萃取纤维用于红茶中农药残留的高灵敏检测

有机氯（OCPs）和拟除虫菊酯（PYs）是两类广泛使用的农药，对自然环境和人类健康具有极大危害。在本研究中，通过原位溶剂热聚合法制备了金属有机骨架/碳化氮纳米片（UiO-66/HOCN）复合材料涂覆的固相微萃取（SPME）纤维，该纤维拥有良好的稳定性，并对OCPs和PYs具有高效的萃取性能。将其与气相色谱-质谱（GC-MS）相结合，建立了用于OCPs和PYs检测的高灵敏分析方法。该方法对9种农药目标物表现出了令人满意的回收率和重现性，具有检出限低（0.03~0.30 ng/L）、线性范围宽（0.1~800.0 ng/L）和线性相关系数良好（≥ 0.9978）等优点。将所建立的方法用于实际红茶样品中农药残留的检测，成功地在实际样品中检测出了艾试剂（6.6 ng/L）、α-硫丹（54.7 ng/L）和联苯菊酯（185.8 ng/L）。实验结果表明，所建立的分析方法适用于复杂基质中农药残留的分析和监测。

In-situ solvothermal polymerization of metal-organic framework/carbon-nitrogen nanosheet-coated solid-phase microextraction fiber for highly sensitive detection of pesticide residues in black tea

Pyrethroids (PYs) and organochlorine pesticides (OCPs) are widely used to control pests and diseases in plants; however, they threaten human health. In this study, a metal-organic framework/carbon-nitrogen nanosheet composite nanomaterial (UiO-66/HOCN)-coated solid-phase microextraction (SPME) fiber was prepared by in-situ thermal polymerization. The prepared UiO-66/HOCN composite material was characterized by transmission electron microscopy, X-ray diffraction, nitrogen adsorption porosimetry, thermogravimetric analysis, and zeta potentiometry. The prepared UiO-66/HOCN composite-coated MSPE fiber was used for the enrichment and separation of OCPs and PYs, which showed good thermal and chemical stability as well as high extraction efficiency. Combined with gas chromatography-mass spectrometry (GC-MS), an efficient and sensitive method for the detection of trace levels of OCPs and PYs was developed. Under the optimal experimental conditions, wide linear ranges (0.1-800.0 ng/L), good linearity (≥ 0.9978), low limits of detection (0.03-0.30 ng/L), and acceptable repeatability (RSD ≤ 8.9%, n=3) were obtained. Typical black tea samples were analyzed by the developed method, and trace levels of aldrin (6.6 ng/g), α -endosulfan (54.7 ng/g), and bifenthrin (185.8 ng/g) were detected. The results demonstrate that the developed method has immense potential for the detection of pesticides in a complicated matrix.