The Degradation And Residue Of Fenoxanil And Prochloraz In Paddy Field And Its Hydrolysis

Fenoxanil as a phenoxy-lactam fungicides, prochloraz is a broad-spectrum imidazole fungicides, both mixed use them that which have get better control effect with rice blast. In order to use they scientifically, rationally and safely in agricultural production to provide data base and basis for evaluating their safety in the environment, the residue analytical method, the dynamic degradation in paddy rice, paddy soil and water, and hydrolysis at different pH values, temperature and other conditions degradation of fenoxanil and prochloraz were studied in this paper.The main contents were as follows:?1? Researched and established an analytical menthod of residue analysis of fenoxanil and prochloraz in paddy soil,water,straw,brown rice and rice hull by gas chromatography simultaneously. By using this analysis method, the minimum detectable amount of fenoxanil and prochloraz were 1.0×10^-11g,detectable limits of fenoxanil and prochloraz residue in paddy soil,water,straw,brown rice and rice hull were 0.0025mg/kg, 0.0005mg/L,0.0025mg/kg,0.0025mg/kg and 0.0025mg/kg.The result shows that the ectent of nicety and exactitude of the analytical test methods all meet the requirement of pesticide determination.?2? A field experiment was conducted to reveal dynamic degradation of fenoxanil and prochloraz in paddy field distributed in Changsha, Changchun and Guiyang. The degradation dynamics rhythm of fenoxanil and prochloraz in paddy filed were studied. The results showed:the degradation of fenoxanil and prochloraz in paddy soil, water and straw were accordance with first-order chemical reaction dynamics equation(Ct= Co^-Kt), the degradation half-lives of fenoxanil in paddy soli, water and straw were 12.7d,3.0d and 4.4d, the degradation half-lives of prochloraz in paddy soil, water and straw were 9.4d,2.0d and 2.4d.?3? A field experiment was conducted to reveal dynamic degradation of fenoxanil and prochloraz in paddy field distributed in Changsha. The final residue experiment of fenoxanil and prochloraz sprayed 2 times and 3 times and interval of 7 days, sampling from the last administration interval of 7,14,21 days in rice crop planting.The results show that according to the recommended dose of 50 g/Mu, spraying 2 times and the safe interval period of 14 days, the average residual content of fenoxanil in brown rice was 0.268mg/kg, and the average of prochloraz was 0.005mg/kg. In addition to individual data outside, were less than MRLvalues for fenoxanil and prochloraz of our making. So 40% fenoxanil and prochloraz WP in paddy field appied under the recommended dose was safe.?4? Studied the degradation behavior of fenoxanil and prochloraz in buffer solutions with different pH values and different temperature. The results shows:fenoxanil and prochloraz have little difference in buffer solutions with different pH values and they stabilized the acid and alkali environment. The rate of hydrolysis of fenoxanil and prochloraz with the ambient temperature rises slightly faster and mixture a certain extent inhibit its hydrolysis.