Residues analytical methods for metamifop and its metabolites.

The high performance liquid chromatographic method was developed for the simultaneous determination of metamifop and three major metabolites in rice and environment.Residues were extracted with a mixture of acetonitrile and water,followed by cleanup with a silica gel column and determined by HPLC with a linear gradient elution program of acetonitrile and water as the mobile phase and ultraviolet detection at 224 nm.The results showed that the linear range of metamifop and its metabolites were from 0.5 mg/L to 20 mg/L,with the correlation coefficients being 0.999 3 to 0.999 9.The minimum detectable concentration of the 4 analytes in soil,rice straw,rice hulls and unpolished grain samples were all 0.10 mg/kg and 0.02 mg/kg in paddy water samples,respectively.Average recoveries were 78.2% to 106.9%,with the coefficients of variation ranging from 2.0% to 11.7%.The results meet the requirement of pesticide residue analysis.