叶菜中三种新烟碱类农药的残留吸附动力学和复合效应初探

A preliminary study on residue sorption kinetics and combined effects of three neonicotinoids in leafy vegetables

采用乙腈提取,QuEChERS方法净化,超高压液相色谱仪检测的方法,动态监测3种新烟碱类农药单一及混合使用后青菜中吡虫啉、啶虫脒及噻虫嗪的残留量变化,并进行吸附动力学分析。结果表明,青菜中3种农药的残留量随时间延长增加,不同处理组分别在24~48h达到残留量最高值,之后残留量缓慢降低并趋于稳定。经卡方检验分析,3种农药在青菜中的吸附行为更符合准一级动力学模型,且决定系数R2大部分大于0.9。3种农药混合使用时存在相互作用,相较于农药的单独使用,混用能够提高各自在青菜中的吸附速率。吡虫啉与啶虫脒之间存在相互促进作用,混合使用后各自的残留量和峰值均提高。但两者与噻虫嗪存在抑制作用,混用后青菜中噻虫嗪的最高残留量降低。该研究为农药复合残留风险评估和田间混合施药提供了基础数据。

The residues in samples were extracted with acetonitrile,cleaned up by d-SPE column,and detected by ultra-performance liquid chromatography,and the pesticide adsorption kinetics were analyzed by dynamically monitoring single and mixed residues of imidacloprid,acetamiprid and thiamethoxam in Brassica chinensis.The results showed that the residues of the three pesticides adsorbed into B.chinensis increased to a maximum value at 24-48 h,then slowly declined,and finally reached a stable state.On the basis of chi-square test,the residue adsorption of three neonicotinoids in leaves conformed to the pseudo-first order kinetic model,with a determination coefficient（R-2） of over 0.9.There existed interactions among the three neonicotinoids and the mixing could improve the adsorption rate of residues in B.chinensis;there was a mutual promotion between imidacloprid and acetamiprid by mixing and their residues and peak value were increased.However,imidacloprid or acetamiprid showed an inhibitory effect on thiamethoxam when mixing,and could reduce the maximum residues of thiamethoxam in B.chinensis.This study provided basic data for residue risk assessment and field application of pesticide mixtures.