Residue Dynamics of Pyridaben in Mixed Formulation of Fenbutatin Oxide and Pyridaben E.C in Citrus and Soil

In order to make up a standard procedure for safe use of pyridaben ( the active ingredient of 5% in mixed formulatio) on citrus, a field experiment was conducted to reveal the residue dynamics and residues of pyridaben in citrus and soil distributed in Changsha and Hangzhou two places.The residues of pyridaben in citrus and soil were determined by gas chromatography with ECD detector.Citrus and soil samples were extracted with acetone and cleaned up by liquid- liquid distribution and column filled with anhydrous sodium sulfate and neu- tral aluminum oxide.When adding of pyridaben at the concentration of 0.05￣0.5 mg·kg-1,The average recovery of pyridaben was in a range of 84.41%￣93.08%,and coefficient of variation was 1.6%￣11.69%. The degradation of pyridaben in 10% fenbutatin oxide and pyridaben E.C in citrus and soil was investigated usingabove method. The results showed that the degradation ofpyridaben in citrus and soil was in accord with the regression equation. The half- lives in cirtus and soil were 3.53￣13.50 d and 3.13￣10.53 d, respectively.When the cirtus was sprayed three times with fenbutatin oxide and pyridaben 10%E.C dilution o(f 1∶1 500 concentration of pyridaben was 33.3 mg·L-1) ,at the 20th day af- ter the last application,the final residues of pyridaben in pulp,peels and soil were ND,ND￣0.0823,ND￣0.078 3 mg·kg-1, respectively, suggest- ing that pyridaben belonged to non- persistent pesticides( T1/230 days) . The result could offer certain scientific experimental referrence for reasonably using the pyridaben and appraisingits enviromental securityin China.