Residue dynamics and safety evaluation of endosulfan in tea

The dissipation dynamics of endosulfan in tea corresponded with the first-order kinetics curve,and the residue amount of endosulfan in tea increased with the increasing of the application dosage.The half life ranged 2.15-2.84 day in oolong tea and 1.65- 1.98 day in green tea,and the residual endosulfan ranged 4.21-12.04 mg/kg in oolong tea and 2.81-8.98 mg/kg in green tea after 7 days of application of 500-2000 times of diluted solution of Thiodan 35 EC at the same condition.The residue amount and half life of endosulfan were significantly different in different areas when applied at the same dosage due to different climatic condition.After 7 days of application,the residual endosulfan in all of tea samples was less than 20 mg/kg,below 30 mg/kg which was fixed by European Union,indicating that the safety interval period for endosulfan fixed at 7 day was adequate.The detection amount and concentration limit of endosulfan was 0.0006ng and 0.006μg/g.The analysis method for residual endosulfan in tea developed in this test had many advantages such as taking less operation time,using less chemical agent,and having better purification.