Analysis of the residual dynamics of chlorothalonil and myclobutanil in bananas

The thesis is entitled to make clear the residual dynamic of chlorothalonil and myclobutanil in bananas in hoping to control the likely disease in the fruit trees.As a kind of main tropic and subtropic fruit growing in Zhangzhou,Fujian,bananas should be protected from being harmed by the drug-residuals like chlorothalonil and myclobutanil.For this purpose,we have studied the residual dynamics of chlorothalonil and myclobutanil in bananas by using a method of GC and field experiment.Results of our studies indicated that the methods here used were simple and convenient.The analysis of samples can satisfy the actual needs when we determine the residue of chlorothalonil with GB/T 5009.105—2003 and myclobutanil with GB/T 5009.146—2003.The original sediment of chlorothalonil in bananas had been found more than that of myclobutanil,which was closely related to their application dosage for the same pesticide.On the other hand,chlorothalonil proved to be faster dissipated than myclobutanil during the first 14d after application,with their dissipation rate going up to the almost same level 14 d to 21 d later.In addition, the dissipation of chlorothalonil and myclobutanil in bananas proved to be well fitted by the first-order kinetics,with the correlation coefficient standing between 0.942 8 to 0.998 0(p 0.01).The experimental results also showed that the degradation coefficient(| k | ) of chlorothalonil was 0.220 45±0.009 15,with T_(1/2) being in a range from 3.1 d to 3.3 d,while T_(0.99) in a range from 20.1 d to 21.7 d.On the contrary,myclobutanil had the | k |,T_(1/2) and T_(0.99) parameters of myclobutanil of 0.170 3±0.000 1,4.1 d and 27.1 d,respectively.Therefore,the chlorothalonil and myclobutanil residues in the banana could hardly be detected 55 - 68 d after the second application.