| The residue analysis method of oxyfluorfen, pendimethalin and actochior in garlic plant and soil was developed by Agilent 6890N GC-μ-ECD.Samples were extracted with an acetone and distilled water, purified by Neutral alumina and Activated Carbon and then determined by GC.The limit of detection by GC-μ-ECD were Acetochlor 4×10-3 mg/kg,Pendimethalin 3×10-3 mg/kg,Oxyfluorfen 2×10-3 mg/kg. Under the set conditions, Acetochlor, Pendimethalin and Oxyfluorfen minimum sample size for the instrument noise peak 3 times, the minimum detectable amount was 3.0×10-12 g,2.0×10-12 g and 1.5×10-12 g. Acetochlor in soil,plant and garlic in the average recoveries were 83.9%-118.1%,87.6-117 .6% and 78.5-94.3%, coefficient of variation were 5.4-14.3%,1.6-9.0% and 3.3-5.6%; Oxyfluorfen in soil,plant and garlic in the average recoveries were 93.4% -109.3%,75.7-117.2% and 80.2-94.6%, coefficient of variation were 2.5-5.4%,2.7-13.2% and 2.9-4.5%; Pendimethalin in the soil,plant and garlic in the average recoveries were 78.9%-106.8%,80.7-118.9% and 76.4-86.4%, coefficient of variation were 2.8-5.9%,4.7-15.8% and 2.3-3.1%.When high dosage 195g a.i/hm2 45% Pendimethalin,Oxyfluoren and Actochior EC was applied in garlic and soil,2-year results showed that:In soil, Acetochlor in the dynamic equation in 2009 was C=1.0378e-0.0707t, r=0.9141,t1/2=0.78 d (Jilin); C=1.1006e-0.0658t, r=0.8513,t1/2=2.32 d (Shandong); Pendimethalin in the dynamic equation in 2009 was C=0.6328e-0.046t, r=0.786, t1/2=4.95 d (Jilin); C=0.7014e-0.0481t, r=0.8321, t1/2=0.77 d (Shandong); Oxyfluorfen in the dynamic equation in 2009 was C=0.2626e-0.0338t, r=0.7945, t1/2=2.42 d (Jilin); C=0.3e-0.0424t, r=0.8441, t1/2=0.82 d (Shandong). In the plant of garlic, Acetochlor in the dynamic equation in 2009 was C=0.0736e-0.0138t, r=0.7991, t1/2= 24.5 d (Jilin); C=0.0807e-0.0331t, r=0.8654, t1/2=8.21 d (Shandong); Pendimethalin in the dynamic equation in 2009 was C=0.1163e-0.1054t, r=0.4756, t1/2=1.4 d (Jilin); C=0.1832e-0.1486t, r=0.7982 t1/2=0.77 d (Shandong); Oxyfluorfen in the dynamic equation in 2009 was C=0.0113e-0.0959t, r=0.8785, t1/2=7.5 d (Jilin); C=0.0212e-0.2091t, r=0.9556, t1/2=2.53 d (Shandong). In soil, Acetochlor in the dynamic equation in 2010 was C=1.1584e-0.0774t, r=0.9517, t1/2=0.03 d (Jilin); C=1.6463e-0.0794t, r=0.9667, t1/2 =1.17 d (Shandong); Pendimethalin in the dynamic equation in 2010 was C=0.5845e-0.0464t r=0.8605,t1/2=4.78 d (Jilin); C=0.8743e-0.0683t, r=0.9559,t1/2=1.41 d (Shandong); Oxyfluorfen in the dynamic equation in 2010 was C=0.2671e-0.0358t, r=0.8442, t1/2=5.91 d (Jilin); C=0.337e-0.0401t, r=0.863, t1/2=2.09 d (Shandong). In the plant of garlic, Acetochlor in the dynamic equation in 2010 was C=0.0747e-0.0241t, r=0.8672,t1/2=10.5 d (Jilin); C=0.0837e-0.0199t, r=0.8896,t1/2=12.32 d (Shandong); Pendimethalin in the dynamic equation in 2010 was C=0.1368e-0.1419t, r=0.8299, t1/2=0.6 d (Jilin); C=0.2073e-0.1723t, r=0.8485, t1/2=0.02 d (Shandong); Oxyfluorfen in the dynamic equation in 2010 was C=0.0167e-0.1554t, r=0.936, t1/2=2.99 d (Jilin); C=0.0293e-0.2769t, r=0.9951, t1/2=2.3 d (Shandong). The results showed that Pendimethalin Oxyfluoren and Actochior are easy to degrade in garlic plant and soil.The final residual concentration of Pendimethalin Oxyfluoren and Actochior in garlic plant and soil was determined. Two years'field test showed that, when 195g a.i/hm2,130g a.i/hm2 45% Pendimethalin Oxyfluoren and Actochior EC was applied in garlic and field. The final residue of Pendimethalin Oxyfluoren and Actochior in garlic and soil fell below detectable limit. The result supported that the final residual concentration was no related to applying dosage. When the applying dosage increased, the residue of Pendimethalin Oxyfluoren and Actochior had no accumulation.Based on these results, refer to Pengdimethalin·Oxyfluoren·Acetochlor EC in garlic plant and soil residue dynamics, the proposed 45% Pendimethalin·Oxyfluoren·Acetochlor EC on the application rate not higher than that of garlic 130g ai/hm2. MRL values were suggested:Acetochlor 0.05mg/kg,pendimethalin 0.1mg/kg,oxyfluorfen 0.05mg/kg. |
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