Method for Residues Analysis of Isoxaflutole and Its Metabolites in Maize

A rapid and sensitive analytical method for the determination of isoxaflutole and diketonitrile (DKN) residues in maize was established based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) and high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). The samples were extracted with acetonitrile and purified with octadecylsilane (C18). The mass spectrometer was performed in multi-reaction monitoring mode, and electrospray ionization in negative mode was selected. The isoxaflutole and DKN residues were quantified by the external standard method using the matched standard solution to compensate for matrix effect. The results indicated that the calibration curves of isoxaflutole and DKN were linear in the range of 0.005-0.5mg/L with correlation coefficients of more than 0.9922. When the addition level ranged from 0.01 to 0.1mg/kg the average recoveries of isoxaflutole and DKN in maize, green maize and straw were 95%-108%, and the relative standard deviation (RSD) ranged from 2% to 11%. The limit of quantitation (LOQ) were 0.01 mg/kg in different matrices. This method has many characteristics, such as simple, rapid and accurate, and can be adapted for the confirmation of isoxaflutole and DKN residues in maize samples.