Techniques Of Determination And Degradation Of Pesticide Residues In Apples

The invention and employment of pesticide have improved the yield of cropper greatly. However, with the usage of it large mount and large illogically, the bad influence of the remnants of pesticides in the foodstuff to human health come to appear, which need to develop celeritive credibilitive sensitive and applied analysis nologies of the remnants of pesticides and decay nologies of the remnants of pesticides.The first step of retention analysis is to extraction and clean up the trace pesticide. It has a direct effect on the accuracy of results. At present , the common methods, for example, Thin-film ChromatograpH ,Gas ChromatograpH, Liquid ChromatograpH and Gas ChromatograpH-Mass Spectum, require analyzing the purer samples. The complicated matrixes will interfere with the retention analyses and damage the instruments. So sampling , contraction and purification are important preparation steps in the retention analyses of prestides.The condition of preparation steps in the retention analyses of prestides in apple sample was studied in thesis, including the choices of the kings of the distilling impregnant, the distilling methods (such as dipping in the distilling impregnant, ultrasonic, mechanical shaking, MAE ,and so on) and the depurating methods. On this work, some pesticide residues degradation techniques such as ozone oxidation and H₂O₂-degradation etc. are used to deal with the Pesticide Residues, at the same time, we research their degradation trend in apple systemicly.The results of the studies are listed as follows:1. An analytical method for determination of organochlorine in apples has been established. The recovery of apple sample is 82.2—98.3%, C.V.=8.45%. So, we concluded that this method is an ideal method for the disposal of organochlorine pesticides residues in concentrated apple.2. An analytical method for determination of organopHospHorus in apples has been established. The recovery of apple sample is 82.9—94.7%, C.V.=7.02%. So, we concluded that this method is an ideal method for the disposal of organopHospHorus pesticides residues in concentrated apple.3. An efficient analytical method for determination of pyrethriods pesticides inapples has been established. The recover rate and the C.V. are 86.9 % and 101.8%. It is a rapider, simpler method than LLE method. Therefore, the proposed method is applicable to the efficient determination of pyrethriods pesticides in the course of apple processing.4. The law of the main organopHospHorus residues in apples ,analyzed by GC using NPD detector, was obtained. The results shows that the degradation of Parathion and MethamidopHos in the environment accords with the degradation exponential equation and R2>0.9, but for Malathion, the R2 is only to be 0.8851. The residues half life (Tl/2)of these 3 kinds of pesticides are 12.6\K 11.8d, 20.3d.5. The law of the main pyrethriods pesticides in apple, analyzed by GC using ECD detector, was obtained. The results shows that the degradation of them in the environment accords with the degradation exponential equation and R2>0.9. The residues half life (Tl/2 )of these 3 kinds of pesticides are 14.2d^ 8.7d> 12.8d.6.Ozone technique has effect on degradation of pesticide residues in apple.The results shows that when the temperature is under 50 "C, ozone disposal temperature is not influence on degradation of Parathion,MethamidopHos, bifenthrin, fenpropathrin, cypermethrin,but Malathion;Pesticide residues in apple are steady when pH is 7.0,or else the pesticide residues can degrade and the rate of pesticide residues at pH>7.0 is greater than pH<7.0;Also the rate of degradation of pesticide residues become more rapid with the concentration of ozone becoming higher.However, the high concentration may be have some disadvantage of apple's quality. In addition, degradation of pesticide residues is relation to the ozone disposal time.Due to the ozone's instability,after 30 minutes, the degradation of pesticide residues has no change.7. Hydrogen peroxide has effect on degradation of pesticide residues in apple.The degree of oxygenation degradation is influenced by pH, concentration, oxygenation time and disposal temperature. Thereinto, hydrogen peroxide disposal temperature has little effect on degradation of pesticide residues. The result of the work is listed as follow:pH is 11, the concentration of hydrogen peroxide is 8% and the disposal of pesticide residues is 20mins.