Study On The Degradation And Removal Of Dimethomorph In Grape

This paper investigated the grape planted in the surrounding areas of Alar and analyzed the use of pesticides in their growing process.We focused on the corresponding relationship between the degradation of dimethomorph after spraying and the quality changes during the ripening process of grape,as well as the residual amount of enoylmorpholine and its safety evaluation.Then we put grapes under room temperature and cold storage,and compared the elimination rules of the dimethomorph in different parts of grapes.We also compared the removal effect of several non-toxic cleaning methods on the residual dimethomorph in grapes through experimental simulation.The basic conclusions of the study are as follows:1.Through investigation of the vineyard and agricultural stores around Alar,the grape planting situation and pesticides with high risk were determined.In Alar,the most widely planted grape is Crimson.There are more fungicides used in the process of planting,and the commonly used pesticide after color-changed period is dimethomorph.Because the interval between the use time and maturity is shorter,there is residual dimethomorph risk.Therefore,we selected the dimethomorph as the research object.2.The conditions for the determination of dimethomorph by high performance liquid chromatography were studied.Using Shimadzu LC-20 AT PDA Detector the flow rate was 1 mL/min,the detection wavelength was 260 nm,the sample size was 10 uL,the ratio of water to acetonitrile in the mobile phase was 60:40,and the column box temperature is 35℃.Under these conditions,the linear range of dimethomorph was 0.05-10 mg/kg,the detection limit was 0.014 mg/kg,the recovery rate was87.72%-98.59%,and the relative standard deviation was 1.77%-4.16%.This method is simple and easy to operate.3.Spray dimethomorph during the color-change period for bagged and not bagged grapes.The degradation dynamics of dimethomorph in the grape growing process were studied.The changes in the nutritional quality of the grape were studied to determine the appropriate picking time and the latest time requirement for the last spraying of dimethomorph.The results showed that when the grapes reached theoptimal harvest time,the residual content of dimethomorph in the bagged and not bagged grapes was within the National regulations for safety,and the initial deposition of the bagged grapes was less than that of not bagged grapes.Bagging can effectively isolate pesticide contamination of fruits.4.The risk of rational application of dimethomorphs remains small,but the risk of residue increases due to early harvesting by farmers.At room temperature and refrigerated conditions,the natural degradation rate of dimethomorph in the peel,pulp and whole fruit of grape samples was studied to determine its safety.The degradation rate of dimethomorph was fastest in the grape skin,and the degradation rate of pesticide residues was faster then slower.It gradually removed with the extension of time,and the degradation rate decreased with the decrease of temperature.The natural degradation of dimethomorphs in grapes followed a first-order kinetic equation with a half-life of 2.68 d at room temperature.5.Use tap water,flour water,sodium bicarbonate,sodium chloride and other non-toxic solvents and the control group(commercial agricultural residue detergent)to clean the grapes containing pesticide residues.The removal effects of several treatments were compared.The results showed that the cleaning effect of sodium bicarbonate solution is the best,and the clearance rate is more than 70%.