Abstract:  The rapid method of methamidophos residues was developed on the principle that the organophosphorus pesticide can inhibit the plant-esterase activity.The plant-esterase from wheat flour were pureed by 70% saturated ammonium sulfate,with the maximum activity at 45℃ and pH4.5～5.5,and the line relation both reactive velocity and reactive time in 10min.The reactive system of determination shows the maximum peak on 480nm,with optimal content of 1.0ml for acetic-β-naphathone,the line relation both absorption value and methamidophos concentration in range of 0.10～1.0mg/kg,the recovery ratio of 84% for tea juice.

Key words: tea, methamidophos, rapid determination