香蕉中2,4-滴残留的快速检测及其消解动态

Rapid determination and dissipation dynamics of 2,4-D in Musa paradisiaca

利用超高效液相色谱-串联质谱建立了香蕉中2,4-滴残留的快速测定方法,研究了2,4-滴在香蕉中的残留消解动态和最终残留量。香蕉样品经乙腈提取,氯化钠盐析分层后,采用负离子电离,多反应监测模式(MRM)测定。结果表明:在1.0~10μg/L范围内,2,4-滴的质量浓度与对应的峰面积间呈良好线性关系,检出限为0.001 5 mg/kg,定量限为0.005 mg/kg。在0.005、0.05和0.5 mg/kg 3个添加水平下,2,4-滴的平均回收率为93%~99%,相对标准偏差为2.5%~3.0%,可满足香蕉中2,4-滴残留检测的要求。田间试验结果表明,2,4-滴在香蕉中的消解半衰期为5.4 d,属易降解农药。最终残留试验结果表明,以有效成分分别为23、35和53 mg/kg的剂量施药,于60 d后采收时,香蕉中2,4-滴的残留量均<LOQ。

An ultra high performance liquid chromatography-tandem mass spectrometry method was developed to study the dissipation dynamics and final residues of 2,4-D in Musa paradisiaca. The M.paradisiaca samples were extracted by acetonitrile, salted out and stratified by sodium chloride. Using negative ion ionization and multiple reaction monitoring, the results showed that there was a good linear relationship between the concentrations of 2,4-D and the corresponding peak area in the range of 1.0 μg/L to 10 μg/L. The limits of detection and quantification of the method were 0.001 5 mg/kg and 0.005 mg/kg, respectively. The average recoveries was in the range of 93% to 99% with the relative standard deviations from 2.5% to 3.0% at three spiked levels of 0.005, 0.05 and 0.5 mg/kg. The method is suitable for the 2,4-D residues detection in M. paradisiaca. The results of field experiments show that the half-life of 2,4-D was 5.4 days, indicating that 2,4-D is a non-persistent and easily degradable pesticide. The final residue test results showed that 2,4-D was 〈LOQ in the M. paradisiaca 60 days after harvest, at dosages of of 23, 35 and 53 mg/kg（effective component concentration）, respectively.