气相色谱质谱联用仪测定玉米中2,4-滴异辛酯的残留量及消解动态

Determination of 2,4-D-Ethylhexyl Residues and Field Decline in Corn by GC-MS

[目的]建立玉米中2，4-滴异辛酯残留量气相色谱质谱检测方法，并研究了其在植株和玉米中的消解动态和最终残留。[方法]样品用丙酮提取后，三氯甲烷萃取，经弗罗里硅土和活性炭层析柱净化，用气相色谱质谱联用仪进行测定。[结果]2，4-滴异辛酯在0．1～2．0mg／L质量浓度范围内呈线性，相关系数0．9993；添加3个不同质量分数，平均回收率为88．7％～101．7％；变异系数为7．2％～9．0％。施药剂量为推荐剂量的1．5倍（3，058．5ga．i．／hm。）时，2，4-滴异辛酯在玉米植株中的半衰期为2．4～6．7d，68％乙草胺-2．4-滴异辛酯·莠去津悬浮剂2。038．9、3,058．5ga．i．／hm2两个剂量，施药1次，测得收获期植株、玉米中2，4-滴异辛酯的残留量均低于美国规定的MRL0．5mg／kg[结论]按照推荐剂量2,038．9ga．i．／hm。处理，建议我国2．4-滴异辛酯在玉米上的MRL值可暂定为0．5mg／kg，施药次数1次。

[Aims] A gas chromatography-mass spectrometry method （GC-MS） was established for determining 2,4-D-ethylhexyl residues in maize and its dissipation rate in plant. [Methods] The samples were extracted by acetone, extracted with chloroform, purified with Florisil column and concentrated, and then determined by GC- MS. [Results] The result showed that the calibration curves was good linear at 0.1 to 2.0 mg/L with the correlation coefficient of 0.9993. The ranges of average recoveries and coefficient variation were 88.7 to 101.7%, 7.2 to 9.0% respectively. The half-life of 2,4-D-ethylhexyl were 2.4 to 6.7 days in the corn plant at 3,058.5 g a.i./ha. The corn were sprayed one time with acetochlor. 2,4-D-ethylhexyl-atrazine 68% SC at 2,038.9 （recommended dosage） and 3,058.5 g a.i./ha respectively, the results revealed that the 2,4-D-ethylhexyl residues in corn were all below the MRL of US （0.5 mg/kg）. [Conclusions] The acetochlor. 2,4-D-ethylhexyl ~ atrazine 68% SC was suggested to apply once in corn at the recommended dosage of 2,038.9 g a.i./ha, the MRL of 2,4-D-ethylhexy in corn may be suggested to be 0.5 mg/kg.