Residue Analysis and Degradation Dynamics of Tebuconazole in Rice

[Aims] The method for the determination of tebuconazole residues in rice plant,rice hull,rice and soil were estimated for evaluating the safety of tebuconazole in paddy field.[Methods] The samples were extracted with acetonitrile,clean-up using a Florisil solid phase extraction cartridge,and subsequent determination by gc-NPD.And the field experiments were investigated in Zhejiang,Shandong and Hunan.[Results] Average recoveries of tebuconazole in rice plant and rice hull were found in the range of 88.80-103.86% at the three spiking levels from 0.05 to 5.0 mg/kg with relative standard deviations of 4.25-14.36%.Average recoveries of tebuconazole in rice and soil were found in the range of 89.19-102.27% at the three spiking levels from 0.02 to 2.0 mg/kg with relative standard deviations of 2.26-8.58%.The limits of quantification(LOQ) in rice plant and rice hull were 0.05 mg/kg.The limits of quantification(LOQ) in rice and soil were 0.02 mg/kg.The field experiments demonstrated that the decline curves of tebuconazole in rice plant were accorded with the first-order kinetics equation,and the half-lives were 0.60 d in Zhejiang,11.48 d in shandong,and 3.14 d in hunan,respectively.The residue of tebuconazole was 0.30 mg/kg in rice plant,0.22 mg/kg in rice hull,0.02 mg/kg in rice and 0.02 mg/kg in soil,respectively,after 21 d of spray.[Conclusions] The method was suitable for the determination of tebuconazole residues in rice.Tebuconazole was easily degradable pesticides in rice plant,and the half-lives were 0.60-11.48 d.