| Copper abietate is a high efficiency,low toxicity and broad-spectrum fungicide,which is used for the prevention and control of citrus canker.Bifenazate is selective foliar spray acaricide,which is uesd for the prevention and control of panonychus citri.The methods for determination of copper abietate and bifenazate in citrus and soil were developed and validated.The residue and dynamic degradation were also studied,which has provided an important theoretical and scientific basis for the formulation of guidelines of the pesticides and product registration in citrus.The residue analysis method of copper abietate was established in citrus and soil by High Performance Liquid Chromatography with photodiode array detecter(HPLC-DAD).The copper abietate could be derived with chlorhydric acid,extracted with Petroleum ether,after being concentrated by evaporation,the residue was reconstituted with acetonitrile and detected in HPLC-DAD.Limit of detection was 1.5×10-6 g,and Limit of quantification in citrus and soil were both 0.3 mg/kg.The average recoveries in citrus peel,citrus flesh,hole citrus and soil were 82.5-93.5%,87.6-94.7%,81.6-96.1% and 85.3-103.5%,respectively,and the relative standard deviations were 2.0-8.3%,2.0-9.8%,1.7-6.1% and 2.8-9.8%.The sensitivity,accuracy and precision of the method well satisfied the essential rules of pesticide residue determination.With this method,samples of citrus and soil were analyzed at different time,then the degradation procedure was corresponding to the mathematics pattern,C= C0E-kt.moreover it had high correlation.The half life of copper abietate in citrus were 1.7~4.3 days,2.2~2.8 days in soil.With sprayed 23% copper abietate on citrus and soil at recommended dosage by two-years(2014-2015)three fields(Guang Dong,Zhe Jiang,Chong Qing)experiment,on the 7th day,14 th day and 21 st after the last application,the final residue of copper abietate in citrus was less than 0.5 mg/kg(LOQ of2014),and in 2015,the pesticide residue in citrus was less than 0.3 mg/kg(LOQ of2015).The residue analysis method of bifenazate was also established in citrus and soil by High Performance Liquid Chromatography with fluorescence detection(HPLC-FLD).Bifenazate could be derived with 4% ascorbic acid,extracted with Acetonitrile by ultrasonic wave,after being concentrated by evaporation,the residue was reconstituted with acetonitrile,cleaned up by primary secondary amine(PSA)and C18,detected in HPLC-FLD.The limit of detection was 1.5×10-6 g and the limit quantification of bifinazate in citrus peel,hole citrus and soil were 0.1 mg/kg,0.05 mg/kg in citrus flesh.The average recoveries of bifenazate in citrus peel,citrus flesh,hole citrus and soil were 90.6-102.6%,87.0-102.5%,93.2-103.5% and 91.8-97.5%,respectively,and the relative standard deviations were 2.2-10.6%,2.4-4.7%,2.4-6.7% and 0.5-3.8%.The average recoveries of bifenazate-diazene in citrus peel,citrus flesh,hole citrus and soil were 95.7-103.7%,96.0-98.4%,90.2-99.9% and 90.5-96.4%,respectively,and the relative standard deviations were 4.1-8.3%,2.4-8.1%,2.9-4.4% and 3.2-4.3%.The average recoveries of both bifenazate and bifenazate-diazene in citrus peel,citrus flesh,hole citrus and soil were93.0-99.7%,92.0-101.6%,91.0-103.0% and 91.7-97.9%,respectively,and the relative standard deviations were 1.1-4.7%,4.4-10.0%,1.2-7.4% and 1.8-4.5%.The sensitivity,accuracy and precision of this method well satisfied the essential rules of pesticide residue determination.With this method,samples of citrus and soil were analyzed at different time,then the degradation procedure was corresponding to the mathematics pattern,C= C0E-kt.moreover it had high correlation.The half life of bifenazate in citrus were 5.1~7.9 days,4.3~7.9 days in soil.With sprayed 43% bifenazate on citrus and soil at recommended dosage by two-years(2014-2015)three fields(Guang Dong,Zhe Jiang,Chong Qing)experiment,on the 7th day,14 th day and 21 st after the last application,the final residue of bifenazate in citrus were 0.1~0.36 mg/kg,less than 0.7 mg/kg(MRL). |
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