Residue and dissipation of epoxiconazole in Triticum aestivum L. and soil under field conditions

The dissipation dynamics of epoxiconazole in wheat plant and soil were evaluated, as well as the terminal residues of epoxiconazole in wheat grains, wheat plants and soil. A simple and effective analytical method for determining epoxiconazole residues in wheat grain, wheat plant and soil was established. The residue levels and dissipation rates of epoxiconazole in wheat and soil were determined by gas chromatography equipped with an electron capture detector (GC-ECD). At fortified levels of 0.01, 0.1 and 2 mg/kg in wheat grains and soil, and 0.01, 0.1 and 10 mg/kg in wheat plant, the recoveries ranged from 82% to 93%, with relative standard deviations (RSD) from 3.0% to 9.7%. The limits of quantification (LOQ) were 0.01 mg/kg for soil, wheat grains and wheat plants. The half-lives of epoxiconazole in wheat plant and in soil were 3.5-8.4 days and 10-30 days, respectively. When at the interval to harvest of 21 days，application rate of 112.5 g a.i./ha and two subsequent applications, the residue levels in wheat grain were below 0.05 mg/kg，and the terminal residues at harvest in wheat grain were lower than the maximum residue limits (0.05 mg/kg) for this pesticide set in China. When used in wheat, the following GAP was recommended: 21 days interval to harvest from last application, two maximum applications, with application rate of 112.5 g a.i./ha.