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    气相色谱法测定荔枝中7种拟除虫菊酯类农药残留量

    GC Determination of Residual Amounts of 7 Pyrethroid Pesticides in Litchi

    • 摘要: 采用气相色谱法测定荔枝中联苯菊酯、甲氰菊酯、氯氟氰菊酯、氟氯氰菊酯、氯氰菊酯、氰戊菊酯和溴氰菊酯等7种拟除虫菊酯类农药的残留量。荔枝样品用丙酮-正己烷(1+1)混合液提取,所得提取液用活性炭柱和中性氧化铝柱的串联柱净化,用DB-35毛细管色谱柱分离,电子捕获检测器检测。7种拟除虫菊酯类农药的质量浓度均在0.05~0.8 mg·L-1内与其峰面积呈线性关系,方法的检出限(3S/N)在0.005~0.01 mg·kg-1之间。在0.05,0.1,0.2 mg·kg-1等3个浓度水平进行加标回收试验和精密度试验,回收率在81.0%~104%之间,测定值的相对标准偏差(n=6)在1.7%~5.1%之间。采用此法测定了荔枝样品中联苯菊酯的含量,所得测定值与行业标准方法测定结果相符。

       

      Abstract: GC was applied to the determination of residual amounts of 7 pyrethroid pesticides, i.e. bifenthrin, fenpropathrin, cyhalothrin, cyfluthrin, cypermethrin, fenvalerate and deltamethrin in litchi. The litchi sample was extracted with a mixture of acetone-n-hexane (1+1), and the extract was purified with activated carbon column and neutral alumina column in series. The analytes were separated on DB-35 capillary column and detected by ECD. Linear relationships between values of peak area and mass concentration of the 7 pesticides were kept in the same range of 0.05-0.8 mg·L-1, with detection limits (3S/N) in the range of 0.005-0.01 mg·kg-1. Tests for recovery and precision were made by standard addition method at 3 concentration levels of 0.05, 0.1, 0.2 mg·kg-1, giving values of recovery and RSD's (n=6) in the ranges of 81.0%-104% and 1.7%-5.1% respectively. The proposed method was used to determine bifenthrin in litchi samples, giving results in consistency with values given by the professional standard method.

       

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