Residue and Risk Assessment of Kresoxim-methyl in Apple Under Field Conditions

Abstract

A rapid and effective method was developed for determination of kresoxim-methyl residue in apple. Field trials were designed to evaluate the dissipation and residue of kresoxim-methyl in apple at Hebei (China), Shandong (China) and Anhui (China). The dietary exposure and risk assessment were also conducted by using the calculation of risk quotient (RQ). The samples were extracted by Acetone and ethyl acetate, cleaned up by Florisil solid phase extraction column and detected by gas chromatograph with DB-1701 capillary column and electron capture detector. The results showed good average recoveries of 80%-99% with relative standard deviations of 0.9%-1.3% at the spiked level of 0.02, 0.20 and 2.0 mg /kg. The limit of detection (LOD) was 1.0×10-12 g and the limit of quantification (LOQ) was 0.02 mg /kg. The results were found that the half lives of kresoxim-methly in apple of Hebei (China), Shandong (China) and Anhui (China) were 6.09, 12.6 and 10.0 d respectively, and the terminal residue was below MRL (0.2 mg/kg) 14 days after application, the RQ of kresoxim-methyl were far below 1. It predicted that it was safe for human being when kresoxim-methyl was used to control Apple tree diseases.