Abstract: The residue decline and pre\|harvest interval of chlorpyrifos mixed with organosilicon surfactants in kidney beans have been studied. The results showed that the dynamic decline of chlorpyrifos was consistent with a first\|order kinetic equation, and the original residue of chlorpyrifos applied singly was relatively lower in kidney bean, while it was quite different in the residue in kidney bean when treated with chlorpyrifos mixed with different organosilicon surfactants and the residue was higher than single treatment with chlorpyrifos or organosilicon surfactants; however, there were less influence on its degradation rate and half\|life. According to the dynamic degradation equation of chlorpyrifos in kidney beans, the theoretical residues were estimated in different intervals, and the pre-intervals were about 5 days calculated with the reference of foreign standards. Therefore, the conclusion was that the residue of chlorpyrifos in kidney bean when mixed with organosilicon surfactants readily met the requirement of CAC standards, but not EU, U.S.A and Japan.

Key words: organosilicon surfactant, cloripyfos, kidney bean, pre-harvest interval, pesticide residue