Determination of the residue behavior of isocycloseram in Brassica oleracea and soil using the QuEChERS method coupled with HPLC

Isocycloseram is a new isoxazoline insecticide that can efficiently control the diamondback moth in cruciferous crops. The aim of this study was to establish a method for the determination of isocycloseram residues in/on cabbage and in the soil using HPLC-UV at 264 nm. A field test was conducted in December 2019 and 2020 to monitor isocycloseram dissipation in Jiangxi, China. Acetonitrile was used to extract isocycloseram from cabbage and soil. C18 and GCB were used to purify cabbage extracts, whereas soil extracts did not require purification. At the addition level of 0.01-1.0 mg/kg, the average recoveries in cabbage and soil were 91.81-109.95% and 89.89-104.08% respectively. After having applied 10% isocycloseram DC, isocycloseram dissipated faster in the cabbage matrix. Isocycloseram residues on cabbage leaves could be removed through simple cleaning methods, especially by soaking in 2% citric acid.