Dissipation behavior of bifenthrin residues in tea and its brew

Dissipation behavior of bifenthrin, a widely used non-systemic acaricide/insecticide, applied under field condition on tea crop in wet (mid-June–October) and dry season (November–mid-June) was studied in green shoots, made tea and its brew. A simple, rapid analytical procedure for the quantification of bifenthrin in these matrices was developed using gas chromatography with electron capture detector. Degradation rate in both wet and dry seasons followed first order kinetics with half lives in green leave in the range 0.52–0.77 and 1.20–1.32 days and in made tea were 0.55–0.60 and 1.03–1.06 days for wet and dry seasons respectively. Processing of green shoots caused considerable loss (⩾42%) of residue and its only partial transfer (1.5–14%) in brew was observed. Based on the observation reported, a waiting period of at least three days before plucking the tea shoots after pesticide application at recommended dose (40 g a.i./ha) may be suggested and considered quite safe from point of health hazards due to toxic effect of residues in brew.