Determination of Cyazofamid and Its Metabolite in Rice Based on Magnetic Zirconia Nanoparticles Sample Cleanup and Its Application to a Dissipation and Residue Study

An analytical method was developed for the determination of cyazofamid (CZFM) and its metabolite CCIM in rice, employing magnetic zirconia nanoparticles (MZNPs) for sample cleanup. MZNPs were synthesized through a one-step hydrothermal process and characterized by multiple techniques. Samples of rice plant, rice hull, and brown rice were extracted using acetonitrile/water, followed by salting out. MZNPs removed the most coextract compared with primary secondary amine (PSA) and zirconia-coated silica (Z-Sep). Satisfactory recoveries (79.6-95.7%; <i>n</i> = 5) of the analytes were acquired with RSDs less than 9.6%. The linearity was good (<i>r</i> > 0.999) over 0.001-1 mg L^-1. The LOQs were 0.01 mg kg^-1. The dissipation and residues of CZFM were studied as the method application. Half-lives of CZFM in rice plants were calculated to be 4.5-9.8 days. At harvest, residues of CZFM > LOQ were not detected in brown rice, indicating a low dietary risk.