加速溶剂萃取-超高效液相色谱-串联质谱法测定茶叶中拟除虫菊酯类农药残留

建立了加速溶剂萃取(ASE)-超高效液相色谱(UPLC)-串联质谱法(MS/MS)测定茶叶中拟除虫菊酯类农药残留的方法。ASE萃取温度为80 ℃,萃取压力为10.34 MPa,以正己烷-丙酮(2∶1, v/v)为溶剂静态萃取5 min,循环一次。萃取液浓缩后经GCB/NH 2-Florisil柱净化,UPLC分离,MS/MS正离子扫描(ESI^+)、多反应离子监测(MRM)模式进行分析,外标法定量。线性回归分析表明:10种拟除虫菊酯的浓度与其峰面积的线性关系显著,相关系数( r )均不小于 0.999 5 ,检出限(LOD)在0.5~5.0 μg/kg 之间,定量限(LOQ)在1.6~16.6 μg/kg 之间;在定量限、0.4 mg/kg 以及最高残留限量(MRL,无MRL的加入1 mg/kg)3个水平进行添加回收试验( n =7),回收率为68.7%~103.8%, RSD为0.8%~13.2%。该方法前处理简单,耗时短,灵敏度和准确度高,可满足茶叶中痕量拟除虫菊酯类农药残留测定的要求。

Determination of pyrethroid pesticides in tea by accelerated solvent extraction and ultra-performance liquid chromatography-tandem mass spectrometry

A method was developed for the determination of pyrethroid pesticides in tea by accelerated solvent extraction (ASE) combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The target compounds were extracted from tea using n-hexane and acetone (2:1, v/v) for 5 min at 10.34 MPa and 80℃ via a single cycle of accelerated solvent extraction. The extract was purified by GCB/NH₂ and Florisil columns, analyzed by UPLC-MS/MS in positive electrospray ionization (ESI⁺) and multiple reaction monitoring (MRM) modes, and quantified by the external standard method. Regression analysis revealed that the linear relationships between mass concentration and peak area are significant for the 10 pyrethroid pesticides, and the correlation coefficients (r) are all not less than 0.9995. The limits of detection (LOD) of the 10 pyrethroid pesticides ranged from 0.5 μg/kg to 5.0 μg/kg and the limits of quantification (LOQ) ranged from 1.6 μg/kg to 16.6 μg/kg. The recoveries of all the pesticides ranged from 68.7% to 103.8% at the spiked levels of LOQ, 0.4 mg/kg and maximum residue limit (MRL) (added 1 mg/kg without MRL) with RSDs ranging from 0.8% to 13.2% (n=7). The proposed method is simple, rapid, sensitive, and accurate, and could be effective for trace analysis of pyrethroid pesticides in tea.