The Residual Dynamics In Soybean Plants And Soil And Photolysis Study Of Cypermethrin

Cypermethrin is one of the most representative specieses in the pyrethroid insecticides controlling many agricultural pest. Because it's effective, low toxicity ,low remaining and widely applying, it drive extensive application in farmer. The determination and degradation of cypermethrin and its photolysis in soil and soybean were studied for the establishment of the MRL standard in this paper.The insecticides are extracted with acetone and petroleum (1: 1 v/v) and cleaned-up with silica gel and activated carbon pillar. Using Benzene:Petroleum (4:1V/ V) pour to wash the pillar many times. The extraction are analyzed by gas chromatography equipped with electron capture (ECD).Analysis of fortified plants (n=3) shows mean recoveries ranged from 87.34-96.10%. The lowest detection level was 9×10-4mg/kg, T_1/2 is 9.30ds and 9.69ds of soil in resent two years, C= 0.7872e^-0.074t和C = 4.2153e^-0.1505t , T_1/2 is 5.03ds and 4.60ds of soybean plant in resent two years,C=3.2073e^0.1287t和 C=8.7596e^0.2438t,On the basis of the residue experiment we have first step studying of the photosensitive and photoquenching effects of deltmethrin, triadimefon, propisochlor on cypermethrin on glass plate by sunlight and high pressure mercury lamp illuminating respectively were studied. The photolytic rates of cypermethrin insecticides were accelerated by triadimefon under these two illuminating lights ; while photoquenching effects of propisochlor on the photodegradation of cypermethrin insecticides were observed under the sunlight and high pressure lamp illuminating. The photolytic rate of the cypermethrin+triadimefon is 1.38 times (under the sunlight)and 1.15 times (under high pressure lamp) quicker than cypermethrin insecticide under the sunlight and high pressure lamp illuminating ;while the photoquenching effects of propisochlor on cypermethrin that the ratio is 0.67 times and 0.69 times under sunlight and high pressure mercury lamp illuminating.