Change of Difenoconazole Residue Levels in CitrusDuring Storage after Soaking

The residue levels of difenoconazole in citrus were studied during storage at different conditions,including preserving temperature,storing time,the concentration of difenoconazole and the position of citrus.The whole fruits were stored at room temperature or at low temperature after treatment with soaking in difenoconazole solution.Difenoconazole residue in citrus was extracted with acetone-petroleum,and determined by gas chromatography(GC).At concentration range of 0.05 ~ 5.0 mg/kg,the recoveries and relative standard deviation were found to be 81.9％ ~91.4％,5.3% ~17.5% respectively,and the limit of detection (LOD) was 0.02 mg/kg.The result showed that the residue levels of difenoconazole related to the concentration of difenoconazole.It's noted that difenoconazole residue may be absorbed less in citrus at low temperature compared with room temperature.In the meantime,residue of difenoconazole was declined gradually with the storage time,with higher residue in peel than in pulp.It' s proposed that 10% WG difenoconazole may be used for citrus storage treatment at a concentration of 100 mg/L,with PHI of at least 21 days.