异丙草胺在玉米和土壤中的残留及消解动态

Residue decline dynamics of propisochlor in corn and soil

采用气相色谱-微池电子俘获检测器（GCμ-ECD）测定了900g/L异丙草胺乳油在土壤、玉米植株和玉米籽粒中的消解动态和最终残留。土壤、玉米植株和籽粒样品用石油醚-丙酮（1∶1,体积比）提取,经液液萃取,弗罗里硅土柱净化,GCμ-ECD检测,外标法定量。结果表明：异丙草胺在各供试样品中的添加水平为0.011-1.1mg/kg时,回收率在78.8%-96.4%之间,相对标准偏差（RSD）为0.54%-10.5%;在土壤、玉米植株和籽粒中的定量限（LOQ）均为0.011mg/kg。异丙草胺在土壤和玉米植株中的半衰期,2009年分别为4.7-5.3d和4.1-4.5d,2010年分别为5.4-5.5d和4.9-5.4d。按推荐高剂量（有效成分）2 400g/hm^2及其1.5倍剂量（3 600g/hm2）施药,于玉米苗后茎叶初期施药1次,在玉米乳熟期和成熟期时,玉米籽粒中异丙草胺的最终残留量均低于定量限。玉米收获时（距施药45d）,土壤和玉米中的异丙草胺残留量均低于参考的MRL值（0.1mg/kg）,说明按规定在玉米田使用900g/L的异丙草胺乳油是安全的。

The residue decline dynamics and final residues of propisochlor in soil,corn plant,corn samples were determined by gas chromatography equipped with μ-electron capture detector（GC-μECD）.Samples were extracted with petroleum/ether-acetone（1∶1,V/V）,and then cleaned up by liquid-liquid extraction and Florisil column,followed by detection with GC-μECD.With fortified concentration of 0.011 to 1.1 mg/kg,the recoveries ranged from 78.8% to 96.4% for corn and relative standard deviations of 0.54% to 10.5%.The limit of quantification was 0.011 mg/kg for soil,corn plant and corn.The half-lives of propisochlor in soil and corn plant were 4.7-5.3 days and 4.1-4.5 days for year 2009,5.4-5.5 day and 4.9-5.4 days for year 2010,respectively.When sprayed once at maize stem leaf with application rate of 2 400 g（a.i.）/ha and 3 600 g（a.i.）/ha,at the milk stage and maturity of corn,the final residues of propisochlor in corn were lower than LOQ.At harvest time（45 days after the treatment）,propisochlor residues in soil and corn were lower than the reference MRL,indicating that use pattern of 900 g/L propisochlor EC on maize is acceptable.