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    QuEChERS萃取结合GC-ECD测定甜玉米中多种有机氯及拟除虫菊酯类农药残留

    Determination of Organochlorine and Pyrethroid Pesticide Residues in Sweet Corn by GC-ECD with QuEChERS Extraction Method

    • 摘要: 10.00 g样品经15 mL乙酸-乙腈(1+99)混合液匀浆提取1 min后,加入氯化钠4~6 g,再匀浆30 s,离心后取上清液1.5~2.0 mL于装有25 mg N-丙基乙二胺、150 mg无水硫酸镁的QuEChERS净化管中,涡旋振荡30 s,离心后取上清液1.0 mL,于40℃氮吹至近干,用正己烷定容至1.0 mL。采用DB-5/DB-35色谱柱(30 m×0.25 mm,0.25 μm)进行分离,电子捕获检测器(ECD)进行测定。12种农药的质量浓度在0.080~1.60 mg·L-1内与峰面积呈线性关系,检出限(3S/N)为0.10~1.5 μg·kg-1,测定下限(10S/N)为0.33~5.0 μg·kg-1。加标回收率为85.6%~119%,测定值的相对标准偏差(n=6)为3.2%~8.0%。

       

      Abstract: The sample (10.00 g) was extracted with 15 mL of a mixture of acetic acid and acetonitrile (1+99) by homogenate for 1 min, then 4-6 g of NaCl was added to the solution. After homogenate treatment for 30 s and followed centrifugation, 1.5-2.0 mL of the supernatant was transferred to the QuEChERS purification tube filled with 25 mg of N-propyl ethylenediamine and 150 mg of anhydrous magnesium sulfate, and treated by vortex oscillation for 30 s. After centrifugation, 1.0 mL of the supernatant was dried at 40℃ by N2 blowing, and the residue was diluted to 1.0 mL with N-hexane. DB-5/DB-35 columns (30 m×0.25 mm, 0.25 μm) were used for seperation, and ECD was used for detection. Linear relationships were found between the peak areas and the mass concentrations of 12 kinds of pesticides in the range of 0.080-1.60 mg·L-1, with detection limits (3S/N) in the range of 0.10-1.5 μg·kg-1, and the lower limits of determination (10S/N) in the range of 0.33-5.0 μg·kg-1. Recovery rates obtained by standard addition method were 85.6%-119%, and RSDs (n=6) were 3.2%-8.0%.

       

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