苯唑草酮在玉米和土壤中的残留消解动态及残留量

Residues and Decline Dynamics of Topramezone in Corn and Soil

[目的]为评价苯唑草酮在玉米上使用的安全性,建立苯唑草酮在玉米中的残留分析方法,并开展其在玉米和土壤中的残留降解研究。[方法]进行2年2地田间试验,样品经二氯甲烷提取、液液分配净化后,高效液相色谱串联质谱在多反应离子监测模式下检测,基质匹配外标法定量。[结果]添加质量分数为0.01~2.0 mg/kg时,苯唑草酮在青玉米、玉米、植株和土壤中平均添加回收率分别为86.7%~101.6%、85.2%~91.5%、84.4%~94.6%和81.8%~91.6%,相对标准偏差分别为2.7%~6.5%、8.4%~11.6%、5.5%~9.7%和1.8%~7.6%。苯唑草酮在植株和土壤中半衰期分别为1.1~1.7、7.2~12.0 d。按27~40.5 g a.i./hm^2用量,喷雾施药1次,收获期采样,玉米植株、青玉米和玉米中苯唑草酮残留量均低于0.01 mg/kg,土壤中苯唑草酮残留量均低于0.02 mg/kg。[结论]该方法快速简便、准确可靠。最终玉米样品中苯唑草酮残留量均低于欧盟和美国规定的最大残留限量(0.01 mg/kg)。

[Aims] In order to evaluate the safety of topramezone in corn, an analytical method for determining topramezone in corn was developed, and a field experiment was conducted to study the residues of topramezone in corn and soil. [Methods] Field experiments were conducted in two locations for two years. The samples were extracted with dichloromethane, cleaned up by liquid-liquid extraction, detected by high performance liquid chromatography-mass spectrometry under multiple reaction monitoring mode, and quantitated by external standard method with matrix-match standard solution. [Results] When the spiked levels were 0.01-2.0 mg/kg, the average recoveries of topramezone in green corn, corn kernel, corn plant and soil were 86.7-101.6, 85.2-91.5, 84.4-94.6 and 81.8-91.6%, and the relative standard deviations were 2.7-6.5, 8.4-11.6, 5.5-9.7 and 1.8-7.6%, respectively. The half-lives （T1/2） in corn plant and soil were 1.1-1.7 and 7.2-12.0 d, respectively. When the application rate oftopramezone was 27 - 40.5 g a.i./ha for one time, the residues of topramezone in corn plant, green corn and corn kernel were below 0.01 mg/kg at harvest time, and the residue of topramezone in soil was below 0.02 mg/kg. [Conclusions] The method was fast, simple, accurate and reliable. The final residues of topramezone in corn kernel were all below the MRL set by EU and USA （0.01 mg/kg）.