螺虫乙酯在柑橘中的残留消减动态

Degradation Dynamics of Spirotetramat Residue in Citrus

采用乙腈提取、N-丙基乙二胺(PSA)和无水硫酸镁净化、液质联用测定的方法,研究了江苏省苏州市、福建省福州市和重庆市柑橘施用螺虫乙酯农药后的螺虫乙酯母体及代谢产物在柑橘和土壤中的残留消减动力学规律以及最终残留情况。结果表明,螺虫乙酯母体在苏州、福州和重庆柑橘中的消减半衰期分别为6.7~9.6、4.7~9.5和7.8~9.5 d,在土壤中的消减半衰期分别为1.4~2.3、1.3~4.9和2.3~3.6 d。在柑橘中按照最高推荐剂量(有效成分60 mg·kg^(-1))和最高推荐剂量的1.5倍(90 mg·kg^(-1))施用螺虫乙酯,施药2~3次时,收获的柑橘中螺虫乙酯含量均低于最大残留限量MRL值(1.0 mg·kg^(-1))。

Spirotetramat is commonly used in citrus orchards for pest control. A study was performed on residues of the pesticide and its metabolites in citrus and soil,their degradation dynamics and their fates in citrus orchards located at Suzhou,Fuzhou and Chongqing,using acetonitrile in extraction,N-propyl ethylenediamine( PSA) and anhydrous magnesium sulfate in purification,and the LC-MS/MS in determination. Results show that half- life of spirotetramat was in the range of 6. 7- 9. 6,4. 7- 9. 5 and 7. 8- 9. 5 d in the fruits from Suzhou,Fuzhou,and Chongqing,respectively,and in the range of 1. 4- 2. 3,1. 3- 4. 9 and 2. 3- 3. 6 d in the soils from the orchards at Suzhou,Fuzhou,and Chongqing,respectively. On such a basis,it is suggested that spirotetramat be applied at a rate of the highest recommended dosage( 60 mg·kg- 1in active ingredient) and a rate,1. 5 times the highest recommended dosage( 90 mg·kg- 1,in active ingredient) twice and three times a season to keep residue of the substance in citrus below the upper limit of MRL( 1. 0mg·kg- 1).