建立了红茶中甲胺磷等56种农药残留的气相色谱-三重四级杆串联质谱（GC-MS/MS）测定方法。实验考察了不同提取剂的提取效果，比较了Cleanert TPT固相萃取柱和QuEChERS的净化效果，优选出以正己烷:丙酮=（7:3，V/V）提取，Cleanert TPT固相萃取柱净化的实验条件；采用优化的GC-MS/MS“定时SRM”模式进行测定，有效解决色谱保留时间出现偏移的问题。结果表明：与QuEChERS净化相比，经TPT柱净化后，54种农药信噪比提高了2倍以上；56种农药的检出限为1~18 μg/kg。在3 μg/kg~600 μg/kg范围内，进行3个浓度水平的加标回收实验，除甲胺磷外，其余55种农药的平均回收率为73~126%，相对标准偏差（RSD，n=6）小于18%。本方法提取、净化效果良好，检测准确、灵敏、高效，适合红茶中56种农药残留的测定。

A novel method was developed for simultaneous determination of methamidophos and other 55 pesticides in black tea using gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The extraction effects of different extraction regents were compared and the purifying effects of Cleanert TPT Solid phase extraction column and QuEChERS were also investigated. The optimum pretreatment conditions for the tea samples were determined as follows: extracting the tea samples by n-hexane: acetone (7:3, V/V) followed by Cleanert TPT column purification. After purified by Cleanert TPT solid-phase extraction tube, the signal-noise ratios of 54 pesticides were improved by two times. The purified samples were then analyzed by GC-MS/MS with “timed SRM” mode, and quantified by internal standard method. Timed SRM can solve the data shortage and quantitative accuracy problem caused by traditional MRM method. The limits of detection were in the range of 1 μg/kg to 18 μg/kg. At the spiked levels of 3 μg/kg to 600 μg/kg, the recoveries of 55 pesticides (except methamidophos)ranged from 73% to 126% with the relative standard deviation less than 18% (n=6). The results demonstrated that this method was accurate and effective, suitable for the determination of 56 pesticides residues in black tea.

广州市科技计划项目([2011]233-34)，质检总局科技计划项目 (No.2011QK326)