气质联用法测定茶叶中氟虫腈、溴螨酯和哒螨灵残留量

Determination of Bromopropylate, Fipronil and Pyridaben Pesticide Residues in Tea by GC-MS

建立了同时测定茶叶中氟虫腈、溴螨酯和哒螨灵残留的气相色谱质谱联用(GC-MS)分析方法。样品经水浸润,乙腈匀浆提取,盐析,石墨化炭黑/氨基固相萃取柱净化,乙腈/甲苯(3:1,V/V)洗脱,浓缩定容后检测。目标化合物经HP-5MS色谱柱(30 m×0.25 mm×0.25μm)分离,于选择离子监测(SIM)模式下进行定性定量分析。结果表明:氟虫腈在0.01-1.0 mg/L,溴螨酯和哒螨灵在0.02-2.0 mg/L浓度范围内呈线性关系,决定系数(r2)>0.991 0;在高、中、低3个添加浓度水平下,3种农药的平均回收率为80.8%-111.2%,相对标准偏差(RSD,n=3)为1.9%-10.9%,方法的定量限(LOQ)氟虫腈为0.005 mg/kg,溴螨酯和哒螨灵为0.01 mg/kg。该方法准确、可靠、灵敏度高,适用于茶叶中氟虫腈、溴螨酯和哒螨灵3种农药残留量的同时检测。

An analytical method was established for the determination of fipronil, bromopropylate and pyridaben in tea by gas chromatography-mass spectrometry （GC-MS）. The sample was extracted with acetonitrile from the tea after treated with a homogenizer. The organic phase was then separated from water phase by adding NaCl. The extract was further purified on a carbon/NH2 cartridge with elution solvents of acetonitrile/toluene （3：1, v/v）. Finally, the target analytes were separated by a capillary gas chromatographic column HP-5MS （30 m× 0.25 mm× 0.25 μm）. A gas chromatography-mass spectrometry operated in selected ion monitoring mode （SIM） was used for the qualitative and quantitative analysis of the constituents, respectively. The results showed that the calibration curves were good linearity in the range of 0.01-1.0 mg/L for fipronil, while 0.02-2.0mg/L for bromopropylate and pyridaben, with the determination coefficients over 0.9910（R2 〉0.9910）, and the average recoveries of the three pesticides ranged from 80.8% to 111.2% with the RSDs of 1.9%-10.9% at high, middle and low spiking levels. The limits of quantifica- tion （LOQs） were 0.005 mg/kg for fipronil, while 0.01 mg/kg for bromopropylate and pyridaben in tea. The method is available for the determination of bromopropylate, fipronil and pyridaben in tea.