纳米四氧化三铁在茶叶农药残留检测中的应用及方法优化

Optimized Application of Fe_(3)O_(4) Nanoparticles for Pesticide Detection in Tea

【目的】建立高效液相色谱-串联质谱测定茶叶中7种农药的分析方法,提高检测效率、降低检测成本。【方法】以多菌灵、嘧霉胺、三环唑、吡虫啉、啶虫脒、灭多威、噻虫嗪等7种农药为目标物,纳米Fe3O4作为净化材料,考察其对茶叶中色素的去除效果,并进行方法评价。【结果】茶叶基质中纳米Fe3O4组的7种农药回收率明显高于石墨化碳黑(GCB)组,最佳用量为300 mg。通过Phenomenex Luna C8(150 mm×2.0 mm×3.0μm)色谱柱梯度洗脱,流动相A为含0.1%甲酸和5 mmol·L^(−1)乙酸铵的水,B为乙腈,多反应监测模式(MRM)监测。在0~50μg·L^(−1)方法线性良好,相关系数(R2)大于0.995;在5、10、50 ng·g−1添加水平下回收率为71.6%~107.7%,相对标准偏差(RSD)为3.95%~13.62%,检出限为0.15~0.60μg·kg^(−1),定量限为0.5~2.0μg·kg^(−1)。【结论】基于纳米Fe3O4建立了高效液相色谱-串联质谱测定茶叶中农药残留的分析方法,该方法稳定、可靠,有效提高了茶叶中农药残留检测的回收率,降低了检测成本。

【Objective】A newly modified analytical method for detecting pesticide residues in tea was developed to improve test efficiency and reduce cost.【Method】Fe3O4 nanoparticles were used to replace the conventional pigment-removing material prior to measurements on pesticide residues,including carbendazim,pyrimethanil,tricyclazol,imidachloprid,acetamiprid,methomyl,and thiamethoxam,in tea by liquid chromatography-tandem mass spectrometry.The methodology was evaluated according to its applicability and validated in a spiked residue test.【Result】The recovery rates on the 7 pesticides under the modified method using 300 mg Fe3O4 nanoparticles for pigment removal pretreatment were higher than graphitizing with carbon black(GCB).The pigment-removed tea extracts were separated with a Phenomenex Luna C8(150 mm×2.0 mm×3.0μm)by using 0.1%formic acid and 5 mmol·L^(-1)ammonium acetate as Phase A and acetonitrile as Phase B for the mobile phase prior to the tandem mass spectrometric analysis under the multiple reaction monitoring mode with external standards.A linearity on the measurements by the new method was achieved within the pesticide concentrations of 0-50μg·L^(-1)showing correlation coefficients(R2)greater than 0.995 for all 7 pesticides.On 5,10,and 50 ng·g^(-1)spiked pesticide samples,average recovery rates of the new method ranged from 71.6%to 107.7%with relative standard deviations of 3.95%-13.62%.The limits of detection(LOD)on the pesticides by the method were between 0.15μg·kg^(-1)and 0.60μg·kg-1,and the limits of quantitation(LOQ)between 0.5μg·kg-1 and 2.0μg·kg-1.【Conclusion】The newly developed pesticide detection method was stable,repeatable,and accurate for the designed purpose.