改良QuEChERS结合超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法快速检测茶叶中95种除草剂残留

基于改良的QuEChERS方法，建立了超高效液相色谱-高分辨质谱同时测定茶叶中95种常见除草剂残留量的定性定量方法。实验以回收率和色素清除效率为指标，通过评估多壁碳纳米管（MWCNTs）、石墨化炭黑（GCB）、N-丙基乙二胺（PSA）和甲苯等在前处理步骤中的影响，优化了经典QuEChERS方法，最终采用含1%（v/v）乙酸的乙腈-甲苯（9：1，v/v）溶液提取，结合12.5 mg GCB、12.5 mg MWCNTs和150 mg PSA混合吸附剂净化的前处理方法。采用Hypersil Gold C18色谱柱分离，在全扫描和自动触发二级质谱（Full MS/dd-MS²）模式下，用四极杆/静电场轨道阱高分辨质谱检测，基质匹配校准曲线定量。结果表明，茶叶中95种除草剂在3个加标水平下的回收率为63.3%~129.1%，相对标准偏差（RSD）为0.7%~15.2%。该法简便、灵敏、快速、假阳性率低，适用于茶叶等复杂植物基质样品中多种除草剂的定性定量分析。

Rapid determination of 95 herbicide residues in tea by modified QuEChERS coupled with ultra-high performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry

A qualitative and quantitative method was established based on modified QuEChERS for the simultaneous determination of 95 herbicide residues in tea using ultra-high performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS). The effects of multi-walled carbon nanotubes (MWCNTs), graphitized carbon black (GCB), primary secondary amine (PSA) and toluene on the precondition step were evaluated in terms of matrix-spiked recovery and pigment clean-up effect. Finally, the modified QuEChERS method was applied, which involved sample extraction with an acetonitrile-toluene (9:1, v/v) mixture containing 1% (v/v) acetic acid, followed by cleaning with 12.5 mg GCB, 12.5 mg MWCNTs and 150 mg PSA. The sample extract was separated on a Hypersil Gold C18 column and analyzed in full scan/data-dependent MS²(Full MS/dd-MS²) mode. The target herbicides were quantified by using the matrix-matched standard calibration. The three-level spiked recoveries were between 63.3% and 129.1% with the precision of 0.7%-15.2%. This method is easy, sensitive and rapid and can be applicable to the determination of trace herbicide residues in tea and other plant-derived complex matrix samples.