The Residual Analysis Study Of Tepraloxydim And Dynamics In Soybean And Soil

A method was developed to determine the residue of tepraloxydim in soil , plant and seeds of soybean, and the residue kinetic of tepraloxydim in the soybean field was studied as well as in different kinds of soil.HPLC-VWD was selected as the analysis method to determine the residue of tepraloxydim. The soil sample was extracted by methanol, after concentration, the sample was analyzed by HPLC. The recovery and CV of the method ranged from 86 to 88% and 0.6 to 5.7% respectively at added level of 0.05¹mg/kg. The determination limit of the method for tepraloxydim residue in soil was 0.005mg/kg. The sample of the plant and seeds of the soybean were extracted by methanol-water with homogenizer, before analyzed by HPLC it was cleaned by adjusting the PH of the solvent when leaching. At added level of 0.05 to 1 mg/kg, the recovery of the method was 74.2 to 89.4% and the CV was 2.0 to 3.1%. Both the recovery and the CV of the methods were quite suitable to determine the residue of the tepraloxydim according to the correlative rules.The degradation of tepraloxydim in soybean field was studied during 2003 and 2004 and the degradation procedure was correspond to the mathematic pattern, C=C₀e^-kt. The half life of tepraloxydim in soil in 2003 and 2004 were 3.08 and 2.83 day and the dynamic equations were C = 0.1672e^-0.2249t and C = 0.2361e^-0.2443t respectively. The half life of the pesticide in the soybean plant were 2.44 and 2.85 day and C=5.6069e^-0.2843t,C=8.7596e^-0.2438t were the dynamic equations in 2003 and 2004. So the pesticide tepraloxydim was easy to degrade in the soybean field. Another study shew the residue of the tepraloxydim in the soil and seeds of the soybean were not detected when the samples were collected at the time of harvest if the EC10% was used when the plant has 2 to3 leaves at the level of 1200 and2400 ml/ha.The degradation of tepraloxydim in different soil was studied under laboratory condition, the experiment show that tepraloxydim was easy to degrade in lessive soil and difficult in saline soil. The half life of the tepraloxydim in lessive , mesdow soil , steppe blacksoil and saline alkalin soil were 8.52 12.81 17.37 and 19.25 day respectively. From the data we conclude that tepraloxydim is stable in high PH environment and unstable in the opposite condition, we can also conclude that the pesticide was easy to degrade in high organic matter content soil and quite stable in the opposite one according to the experiment. Another study show that the half life of tepraloxydim in mesdow soil decrease much as the temperature increase. At temperature 15℃, 25℃, 35℃, 45℃,the half life were 18.05, 12.56, 2.46 and0.76 day respectively. The half life of tepraloxydim was quite long at low temperature and decrease as the temperature increase, but the degree of decreasing was not so distinct at quite high temperature. The experiment show the temperature range 25 to 35 °Cwas suitable for the degradation of tepraloxydim in soil.