金银花规范化种植中噻虫嗪安全使用标准的研究

Study on standard of safe application of thiamethoxam on GAP of Lonicera japonica

建立了噻虫嗪在金银花中的残留分析方法,并研究了其在金银花中的消解动态和最终残留量,以及对其安全使用标准进行讨论。采用甲醇超声提取、二氯甲烷液液分配及SPE柱净化后,通过HPLC-UV检测分析。结果表明不同添加浓度下噻虫嗪回收率为84.91%-94.44%,RSD为1.7%-5.0%,满足农药残留检测要求。田间试验采用推荐剂量（90 g·hm^-2）和高剂量（135 g·hm^-2）进行处理,2年实验结果表明,农药噻虫嗪在金银花上施用后7 d可消解90%以上,半衰期为1.54-1.66 d。农药噻虫嗪在金银花中的消解速度较快,噻虫嗪在金银花中的最高残留限量推荐值为0.1 mg·kg^-1,金银花规范化种植中建议每年施用25%噻虫嗪水分散粒剂剂量在90-135 g·hm＆-2,喷施3次以下,最后一次施药和收获时间的安全间隔期可推荐为14 d。

The paper is aimed to establish a method of residue analysis for thiamethoxam and to study its degradation dynamic and final residue and its standard of safe application of thiamethoxam on Lonicera japonica. Samples extracted with methanol by ultrasonication were purified with dichloromethane by liquid-liquid extraction and SPE column and analysed by HPLC-UV. The results showed that average rate was 84. 91%-94. 44% and RSD 1. 74%-4. 96% with addition of thiamethoxam in respectively diverse concentration,which meets inspection requirement of pesticide residue. Two kinds of dosages of thiamethoxam were treated- varying from recommended dosage（ 90 g·hm^- 2） to high dosage（ 135 g·hm^- 2）,Results of two years test showed that thiamethoxam was degraded more than90% seven days after application and the half- life period of thiamethoxam was 1. 54-1. 66 d. The digestion rate of thiamethoxam was fast in the L. japonica. The recommended MRL of thiamethoxam in the L. japonica is 0. 1 mg·kg^- 1,the dosage of 25% thiamethoxam WDG from 90-135 g·hm^- 2is sprayed less than three times a year on L. japonica and 14 days is proposed for the safety interval of the last pesticide application＇s and harvest＇s date.