| A reliable analytical method for determining the residues offludioxonil, metalaxy-M and cyantraniliprole by UPLC-MS/MS combined modified QuEChERS was developed, and applied to investigate the residue and degradation of three pesticides in potted pepper and soil after soil application under greenhouse condition. The target compounds were extracted using acetonitrile, cleaned up with QuEChERS purification methods. At the 0.01 to 0.1 mg/kg levels, the average recoveries of three pesticides in pepper and soil were in the range of 93.4%-111.6%, 86.9%-108.8% and 82.0%-106.4%, respectively; with relative standard deviations were1.3%-8.2% and 2.6%-6.8% for intra-day and inter-day determinations, respectively. The limit of quantification （LOQ） of three pesticides were all 0.0005 mg/kg in pepper and soil. Under greenhouse conditions, the half-lives of three pesticides in pepper and soil were 5.4, 8.7 and 13.9 d, respectively,suggesting that these compounds were easily degradable in environment. The final residues of three pesticides in pepper were lower than 0.1 mg/kg at the interval 14 dafter soil application at recommended dosage and 1.5-fold of recommended dosage for once. Because pesticide application in potted vegetables is a special situation, there is no relevant standards in China at present.The results were helpful for understanding the persistance of these pesticides in potted pepper after soil application mode, and providing theoretical basis for the establishment of related standards. |
