液相色谱-串联质谱法测定10种食品中四溴菊酯残留

摘要

建立了测定蔬菜、水果、茶叶、大豆等10种食品中四溴菊酯残留的高效液相色谱-串联质谱( HPLC - MS/MS)分析方法.样品以乙酸乙酯(蔬菜、水果、茶叶样品)或乙腈(大豆样品)为提取剂,上层有机相经浓缩、固相萃取小柱净化,流动相定容后,采用HPLC在Agilent ZORBAX Eclipse XDB C18色谱柱上,以甲醇和缓冲盐溶液(0.1％甲酸- 10 mmol/L乙酸铵)为流动相进行梯度洗脱分离,以串联质谱在多反应监测(MRM)模式下测定,基质外标法定量.结果表明,四溴菊酯的质量浓度在20～1000 μg/L范围内线性关系良好,相关系数为0.999 8；在0.01、0.02、0.1 mg/kg(粮谷类、茶叶、大豆样品)和0.005、0.01、0.05mg/kg(果蔬类样品)加标水平下的回收率为75％ ～ 92％,相对标准偏差(RSDs)为4.0％～12.6％ (n=6),定量下限(S/N≥10)为0.01 mg/kg(粮谷类、茶叶、大豆样品)和0.005 mg/kg(果蔬类样品).该方法不受溴氰菊酯干扰,可直接测定四溴菊酯,克服了以往方法只能测定四溴菊酯和溴氰菊酯总量的不足.%A high performance liquid chromatography - tandem mass spectrometric( HPLC - MS/MS) method was developed for the determination of tralomethrin residues in ten kinds of plant-based foods, including vegetables, fruits, tea and bean. The samples were extracted with ethyl acetate for vegetables, fruits, tea, and acetonitrile for bean. The extract was concentrated and purified by solid phase extraction (SPE). Chromatographic separation was achieved by HPLC on an Agilent ZORBAX Eclipse XDB C18 chromatographic column using methanol -0. 1% formic acid with 10 mmol/L ammo-nium acetate as mobile phase by gradient elution. The detection was performed by tandem mass spec-trometry under multiple reaction monitoring mode and the quantification by the matrix-matched exter-nal standard method. Results showed that the calibration curve of tralomethrin was linear in the range of 20 - 1 000 μg/L with a correlation coefficient of 0. 999 8. The recoveries for tralomethrin at three spiked levels (0.01, 0.02, 0.1 mg/kg for cereals, teas and beans and 0. 005, 0.01, 0. 05 mg/kg for fruits and vegetables) were between 75% and 92% with relative standard deviations( RSDs, n = 6) of 4.0% -12.6%. The limits of quantitation( S/N≥10) were 0. 01 mg/kg for cereals, teas and beans, and 0. 005 mg/kg for fruits and vegetables. The method can be used to separate and i-dentify deltamethrin and two diastereoisomers of tralomethrin while the gas chromatography (GC) with electron-capture detector( ECD) and MS detector, which are routinely applied in the analysis of pyre-throid pesticides in foods, but cannot distinguish these two pesticides.