Residue and Degradation of Bifenthrin in Dry Tea

A supervised trial was done to investigate the final residue and degradation dynamics of bifenthrin in dry tea.Moreover,the effects of processing style and tea variety on the residue dissipation of bifenthrin in tea were analyzed.Fuding and Qianmei 601 were selected as the experimental varieties.Spraying treatments were carried out using 40mL of 25% bifenthrin EC diluted in 15L water.Tea leaves were picked artificially and processed into dry tea using Chinese roasted technics and refined baked technics separately at 2h,1d,3d,8dand 11d after spraying.The bifenthrin content in dry tea was measured using GC-ECD method.The results showed that the effects of processing style and tea variety were significant on the residue of bifenthrin in tea and the average degradation rate were 91.8% in 8 days after spraying.The degradation behavior of bifenthrin can be described by first-degree dynamic pattern in dry tea and the half-lives of bifenthrin were2.31-3.47d.If taking the bifenthrin residue in tea of 5mg/kg as the reference index,it was suggested that the tea leaves should be picked after 3 days of spraying under the dose condition of bifenthrin mentioned in this article.