Dissipation, residues and risk assessment of metconazole in wheat

In order to evaluate the residue behavior and dietary intake risk of metconazole applied to wheat, the residual trial of metconazole in wheat were carried out in Beijing, Anhui and Heilongjiang provinces. A new method was developed to determine the residue of metconazole in wheat. The risk assessment to different populations based on data of terminal residues in wheat was investigated. The samples were extracted with acetonitrile, purified by florisil SPE column, and determined by gas chromatography coupled with nitrogen phosphorus detector (NPD). At fortified levels of 0.02-10 mg/kg, recoveries of metconazole in wheat and straw were between 81%-101%, with RSD of 2.14%-9.10%. The limits of quantification (LOQs) were 0.02 mg/kg in grain, 0.04 mg/kg in straw. The results indicated that the dissipation of metconazole in straw fitted to the first order kinetics with half-lives of 4.9-7.3 days. At harvest period, the highest residue of metconazole in grain was 0.037 mg/kg, which was lower than the maximum residue limit (MRL, 0.15 mg/kg) set by the United States and European Union. The risk quotients (RQs) were between 0.001-0.002 for different populations in China, which indicated its low risk in wheat.