Degradation Of Diafenthiuron And Pyridaben In Orangery And Its Migration In Soils

40%diafenthiuron and pyridaben SC is an insecticide and acaricide with new type, mainly used in pests control of fruit trees. As a new mixed pesticides, previous studies of its residue after used it in environment of orangery are rarely.In order to determine the safety of40%diafenthiuron and pyridaben SC in orangery,this paper had studied the dagradation of diafenthiuron and pyridaben in orangery and the migration in different soils. These studies could provide some fundamental datas for scientific application of diafenthiuron and pyridaben.The main contents were as follows:(1)Studied and established the method of diafenthiuron and pyridaben residues for the determination in citrus soil and citrus by HPLC. Diafenthiuron were extracted with acetonitrile, PSA purified; pyridaben were extracted with acetone, petroleum ether extracted and neutral aluminum oxide column purified.The results showed: diafenthiuron, the average recoveries were96.56%in the soil samples and90.16%in the citrus sample; pyridaben, the average recoveries were93.97%in the soil samples and97.30%in the citrus samples. The extent of nicety and exactitude of the analytical test methods all meet the requirement of pesticide residue determination.(2) A high performance liquid chromatographic method was developed for the detemination of diafenthiuron and pyridaben residual amount in soil at same time. The results showed:the average recoveries of determination was96.27%, the average recoveries of pyridaben was91.23%.The extent of nicety and exactitude of the analytical test methods all meet the requirement of pesticide residue determination.(3) The degradation dynamics rhythm of diafenthiuron and pyridaben in Citrus was studied. The results showed:the degradation of diafenthiuron and pyridaben in citrus sampes were accordance with first-order dynamic equation Ct=C0e-kt; the degradtion half-lives of diafenthiuron in soil and citrus sampes were5.31d and5.68d, the degradtion half-lives of pyridaben in soil and citrus sampes were7.73d and8.37d.(4) The migration of diafenthiuron, pyridaben and mixed pesticides in five different soils were studied. Studied of the soil chemical and physical properties on migration. And compared the migration of diafenthiuron, pyridaben and mixed pesticides. The results showed:diafenthiuron and pyridaben were difficult to move pesticides. In the case of40%diafenthiuron and pyridaben SC exists the migration has declined than diafenthiuron and pyridaben in the soil only.