| Difenoconazole(cis,trans-3-chloro-4-[4-methyl-2-(1H-1,2,4-triazol-1-met hyl),1,3-dioxin-pentane-2-methyl]-phenyl-4-chlorophenyl ether) is one of the fungicide come from Syngenta. It drive extensive application in farmer for its protective, therapeutically and effective. In order to better apply to agricultural production, the determination and degradation of difenoconazole were studied by using Gas Chromatography in this paper. The main results as follows:1. The degradation kinetics of difenoconazole in kidney bean, grape and celery according with the first-degree reaction pattern, C=Coe-kt. The half-lives were 10.0 d in kidney bean,8.8 d in grape and 19.7 d in celery respectively in Beijing field in 2008, and 3.6 d in kidney bean,17.0 d in grape and 7.3 d in celery in Jinan field. The speed of degradation was fast in plants which can meet the safety of food in daily life.2. The degradation kinetics of difenoconazole in soil accords with the first-degree reaction pattern, C=Coe-kt. The half-lives were 125.8 d (kidney bean field),69.3 d (grape field),63.6 d (celery field) in Beijing 2008,51.3 d (kidney bean field),43.6 d (grape field), and 60.3 d (celery field) in Jinan 2008. The half-lives were different in different conditions of the kind of fiele crops. This may because the influence by base material, weather and the physicochemical property.3. The result of the final residue trial of difenoconazole showed that the final residue was related to the application dosage, application times and harvest interval. The final residue was increased as application dosage and application times increased, and as the harvest interval decreased. According to recommend, difenoconazole should be applied on kidney bean at the dosage of 75-125 g.a.i.-ha-1 for 3 times with 7 days application interval, and the pre-harvest interval should be 7 days; difenoconazole should be applied on grape at the dosage of 75-125 g.a.i.-ha-1 for 2 times with 10 days application interval, and the pre-harvest interval should be 14 days; difenoconazole should be applied on celery at the dosage of 100-125 g.a.i.-ha-1 for 2-3 times with 7 days application interval, and the pre-harvest interval should be 4 days. The final residues were all satisfied with the present international value of the MRL.4. The result of hydrolysis test showed that the degradation of difenoconazole in buffer solution is mainly impacted by the pH. The pre-harvest interval more than 166 days in buffer solution(pH 5-9) at 25℃-50℃. It tended to the basic. The hydrolysis was difficult with the increase of temperature.5. The result of photolysis test showed that the degradation of difenoconazole was fast in different organic solvents, different buffer solution and different types of soil. The half-life of difenoconazole was 96.3 min,129.8 min and 143.2 min in acetone, hexane and acetonitrile respectively; the half-life of difenoconazole was 7.1 h,8.0 h and 6.2 h in acidic solution, neutral solution and alkaline solution respectively. It tended to the basic. Second is acidic solution. It is catalyzed by acid and alkaline solution which accord with the result of hydrolysis test; The half-life of difenoconazole were 6.2 h,29.9 h,66.8 h,234.2 h and 308.1 h in soil from Yunnan, Shandong, Beijing, Heilongjiang and Jiangsu respectively. The photolysis in soil was impacted by types of soil and physical-chemical properties. At last, the speed of photolysis was increased as added concentration decreased.
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