Residues and decline study of flufiprole in corn and soil

A new method was developed to determine the residue decline dynamics and final residues of flufiprole in soil, corn plant and corn samples with gas chromatography detection. Flufiprole residue was extracted from corn plant and corn samples with acetonitrile, and with acetone for soil samples. Soil samples were cleaned up by liquid-liquid separation. Corn samples were cleaned up by Oasis HLB-SPE, followed by detection on gas chromatography with electronic capture detector (GC-ECD). The average recoveries of flufiprole in spiked samples with fortified level of 0.01, 0.05 and 0.5 mg/kg were between 80%-86% with relative standard deviations from 5.1% to 8.0%. The limit of quantification (LOQ) for flufiprole was 0.01 mg/kg in soil, corn plant and corn samples. The half-lives of flufiprole were 6.77 days in soil and 2.44 days in corn plant, respectively. When sprayed once at maize stem leaf with application rate of 37.5 and 56.25 g(a. i.)/hm2, the final residues of flufiprole in corn were lower than LOQ at the milk stage and maturity of corn. At harvest time (90 days after the last treatment), flufiprole residues in soil and corn were lower than the reference MRL of China(0.02 mg/kg, fipronil MRL of China in corn).