亚临界水萃取及气相色谱-串联质谱法检测红茶中多种农药残留

建立了亚临界水萃取及气相色谱-串联质谱(GC-MS/MS)检测红茶中21种有机氯和拟除虫菊酯农药残留的方法。在萃取压力为5 MPa条件下,样品经150 ℃的亚临界水提取15 min后,将目标物转移至丙酮-正己烷(1:1, v/v)中,经ENVI-Carb固相萃取净化小柱净化,DB-5毛细管气相色谱柱分离,在多反应监测(MRM)模式下进行MS/MS检测,基质匹配溶液内标法定量。各目标物在5.0～320.0 μg/L范围内线性关系良好,相关系数均大于0.99,其定量限(信噪比(S/N)＞10)为50 ng/g,检出限(S/N＞3)为10 ng/g。茶叶基质中添加50、100和200 ng/g的标准品时,21种农药的回收率为70.18%～119.98%,相对标准偏差(RSD)为5.01%～11.76%。该方法的灵敏度、准确度和精密度均符合农药残留测定的技术要求,适用于红茶中有机氯和拟除虫菊酯农药残留的检测。

Determination of multi-pesticides in black tea by subcritical water extraction and gas chromatography-tandem mass spectrometry

A gas chromatography-tandem mass spectrometry (GC-MS/MS) method with subcritical water extraction was developed for the determination of 21 organochlorine and pyrethroid pesticides in black tea. Under the extraction pressure of 5 MPa, the target compounds were extracted with subcritical water at the temperature of 150 ℃ for 15 min, transferred into acetone-n-hexane (1:1, v/v), and cleaned-up by an ENVI-Carb solid phase extraction (SPE) column. The GC separation was performed on a DB-5 capillary column. The pesticides were determined by MS/MS in multiple reaction monitoring (MRM) mode and quantified by matrix-matched internal standard method. The calibration curves showed good linearities in the range of 5.0~320.0 μg/L with the correlation coefficients greater than 0.99. The limit of quantification (S/N＞10) was 50 ng/g, and the limit of detection (S/N＞3) was 10 ng/g. The recoveries of pesticides spiked in the tea at three levels of 50, 100 and 200 ng/g were ranged from 70.18% to 119.98% with the relative standard deviations (RSDs) of 5.01%~11.76%. The sensitivity, accuracy and precision of the method meet the technical standard of the pesticide determination. The method can be applied to the determination of organochlorine and pyrethroid pesticides in black tea.