The Residual Dynamics In Cabbage And Soil And Adsorption Study Of Fenoxaprop-p-ethyl

Fenoxaprop-p-ethyl (FNE) is a selective post-emergence herbicide controlling annual grass weed in dicotyledonous crops. The determination and degradation of FNE and its metabolite, fenoxaprop-p (FNA), in soil and cabbage were studied. The adsorption of FNE by soil was also studied.The soil samples were extracted with ethyl acetate-sodium hydrogen Carbonate solution. After partition of the parent compound and its metabolite, the organic phase containing FNE was cleaned up with dichloromethane. Then combine the FNE and FNA. HPLC analysis was performed with Zorbax C18 column. FNA and FNE were eluted with methanol-water mixtures. The cabbage samples were extracted with acetone-sodium hydrogen carbonate solution mixtures to attain FNE, and then cleaned up with alumna. The HPLC analysis is the same as the soil. In order to attain FNA, the cabbage samples were extracted with hydrochloric acid-methanol mixtures and cleaned up with silica. The HPLC analysis was performed with Zebra C8 column. FNA was eluted with methanol-glacis acetic acid solution. The recovery of the method was 83.28-90.00% and C.V. was 0.88-3.88%. The detect limit of FNE in soil and cabbage was 0.01ug/g, and FNA was 0.02ug/g.The degradation of FNE and FNA in soil and cabbage was studied by HPLC method and a 2-yr field experiment in Jilin province. The soil and cabbage were treated with FNE at 360mL/hm2. Sample the soil and cabbage at different time to do degradation dynamics analysis. The degradation procedure of FNE was correspond to the mathematic pattern, C=C0e-kt. In soil, the dynamic equation in 2001 was c=0.1929e-0.0113t and the half-life was 44.3h, and the dynamic equation in 2002 was c=0.2003e-0.0115t and half-life was 43.2h. FNA was detected in soil after 5h and the highest amount was at 72h. In cabbage, the dynamic equation in 2001 was c=0.2376e-0.1489t and the half-life was 6.4h, and the dynamic equation in 2002 was c=0.2596e-0.1562t and half-life was 6.0h. FNA was detected in cabbage after 3h and the highest amount was at 8h. FNE and FNA were not detected in soil and cabbage at harvest. The result showed that FNE was dissipated in soil and cabbage rapidly and the degradation of FNE in cabbage was more quickly than in soil.The adsorption of FNE by soil was studied by the equilibrium method. Two different soil types were used in the study.0.81ug/g FNE solutions (25mL) was added to soil (5g) and was shaken on a shaker at 25C. Sample the FNE solutions at different time. A GC method wascarried out to detect the FNE amount in water. The result showed that FNE could be adsorbed by the two soils strongly.