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Bromothalonil is a widely used fungicide. In this paper, the residue dynamics and the final residues of bromothalonil in the banana and soil were determined by gas chromatography equipped with an electron-capture detector (GC-ECD), and residue detection method of bromothalonil was studied ang optimized with it, and adsorption in soil. The study provides reference for making the rules of MRL and using the pesticide properly in banana, and provides the scientific basis for evaluate environmental security of bromothalonil. The results were as follows:1.The analysis method for determination of bromothalonil in banana and soil by GC-ECD was established.The samples were extracted with acetonitrile and cleaned-up with florisil column, then eluted with acetone:hexane (5:5v/v), volume with hexane, and determined by gas chromatography equipped with an electron-capture detector (GC-ECD), GC-ECD test condition of bromothalonil:capillary column:DB-1 (30m×0.32 mm×1.0μm); temperature programming:initial temperature 80℃, hold time 0.3min, ramp 25℃·min-1 to 240℃, hold time 0.5min, ramp 60℃·min-1 to 280℃, hold time 8min; detector temperature 300℃; injector temperature 250℃; carrier gas:nitrogen, purity(?)99.999%; Splitless injection; makeup 50mL·min-1; retention time 7.22min; the minimum detectable amount of bromothalonil (LOD) for the 8×10-12 mg, the lowest detectable concentration of banana (LOQ) was 0.02 mg·kg-1On the level of 0.05～0.5 mg·L-1,the results of recoveries showed that the recovery ratio of bromothalonil was 80% to 105% in the soil,the relative standard deviations was 1.8% to 4.8%, the recovery ratio in banana was 91% to 100%,relative standard deviation was 1.8% to 4.4%,. This method was simple, rapid, sensitive, high accuracy, good precision,in line with the requirements of pesticide residues.2. The residue dynamics of bromothalonil WP in banana and soil.The dosage 2250 g(a.i.)·hm-2 bromothalonil WP was applied in banana and soil, two years’field test showed that the degradation procedure of bromothalonil was correspond to the mathematic pattern,C=Coe-kt. In banana, the dynamic equations were C=0.4294e-0.3771t, R2=0.9289 (2009); C=0.4974e-0.376t, R2=0.9126 (2010); the dynamic equations in soil were C-0.4914e-03611t, R2=0.91 (2009); C=0.122e-0.3735t, R2=0.9653; The half-life of bromothalonil was 1.8 d in banana,1.9 d in soil in 2009 and in 2010, Bromothalonil decomposed more than 90% in banana and in soil after had been sprayed for 14 d. Bromothalonil was dissipated rapidly in banana and soil, bromothalonil is easy to degrade.3. The final residue of bromothalonil in the banana and soil was studied.The recommended maximum dose was the low dose,1125 g (a.i.)·hm-2. The double of The recommended maximum dose was high concentration,2250 g (a.i.)·hm-2. The pesticide was respectively sprayed three times and four times, the samples was collected at each seven days interval, after the last spraying 7d, 14d, 21d The results demonstrated that the final residue dose were 0.03-0.066mg·kg-1 in banana and 0.041-0.068mg·kg-1 in soil. The residues in 21 d after spraying were 0.03mg·kg-1 in banana and 0.04mg·kg-1 in soil, the maximum residue limit of bromothalonil with reference to that in other crops 0.1 mg·kg-1 was recommended. It was suggested that the drug dose of 40% bromothalonil WP should not exceed 2250 g (ai)·hm-2 when reasonably used, the safe internal time was no less than 7d. It was safe to eat after spraying bromothalonil to harvest banana.4. The absorption of bromothalonil in clay, mud, sand were also studied in this paper that the absorption of bromothalonil mainly concerned with the soil organic matter content, under the same conditions, the soil with high organic matter behave the highest absorption of bromothalonil, the soil behave relatively less absorption of bromothalonil with the reduction in organic matter content. The adsorption of bromothalonil in soil mainly based on physical adsorption, which is susceptible to soil adsorption leading to relatively small impact on the environment.
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