Residue Analysis And Digestion Of Fludioxionil On Grapes And Soil

The people's material and spiritual living standards are constantly improving.The health and safety problems caused by the residual pesticides in food have aroused widespread concern in the society.Our country is a large producer of grapes,in recent years,grape production ranks first in the world.Grape is one of the four major fruits and is highly favored by consumers.Fludioxonil is a non-endogenous phenylpyrrole broad-spectrum fungicide.It is mostly used to control fungal diseases,and has special effects on gray mold.At present,there is still a lack of residue limit standard for fludioxonil in grapes in China.According to the CAC,the MRL for fludioxonil in grapes is 2.00 mg/kg.This paper explored and established the residue analysis method for fludioxonil in grapes and soil.Through field experiments,the dynamics and safety of fludioxonil in grapes and soil were studied.The main results are as follows:1.Established a method for the detection and analysis of fludioxonil residues in grapes and soil:The extraction efficiency of fludioxonin in grapes and soil was compared by six extraction solvents:dichloromethane,acetonitrile,acetonitrile?1%formic acid?,petroleum ether,n-hexane,and ethyl acetate.Dichloromethane was chosen as the extraction solvent of fludioxonil in grapes,and acetonitrile was used as the extraction solvent for fludioxonil in soil.At the same time,the effects of mechanical oscillation,ultrasonic vibration and homogenization on the extraction efficiency of fludioxonil in grapes and soil were investigated.It was found that mechanical oscillation was the best.By comparing the purification effects of four different adsorbents?Flori silica column,silica gel column,C18column,and PSA+C18?purification column and the effect on the recovery of the addition,Finally,the Florisil column was identified as a purification cartridge for the grapes,while the soil was selected with a PSA and C₁₈8 mixed purification cartridge.Final determination of the residual analysis method:Grape samples were extracted with dichloromethane and mechanically shaken for 60 min,florisil SPE column was used for purification;soil samples were extracted with acetonitrile and mechanically shaken for 60min,C₁₈8 and PSA cartridges were used for purification;sample solutions were determined by HPLC-UV detector.The limit of detection?LOD?of fludioxonil was 5×10^-1010 g.When the concentration was 0.02-2.0 mg/kg,the recovery of fludioxonil in grape was 89.0%-95.8%,relative standard deviation.It was 1.10%to 7.10%.The recovery of fludioxonil in soil was88.2%-90.5%,and the relative standard deviation was 0.80%-6.40%.The limit of quantitation?LOQ?of fludioxonil in grapes and soil was 0.02 mg/kg.The sensitivity,accuracy,and precision of this residue analysis method were all in line with the standards for pesticide residue analysis.2.The residue dynamics and safety of fludioxonil in grapes and soil were studied:During the period from 2016 to 2017,the dosage of the dynamics of residual degradation in the field was 200 mg ai/kg.After 7 days of application,the degradation of fludioxonil in grapes and soil was higher than 50%.After 14 days,the dose of fluocinonil in soil was The degradation amount was higher than 80%.After 21 days,the degradation of fludioxonil in grapes was more than 85%.The final residue test results showed that 40%fludioxonil suspension was applied at a recommended dose of 133.3 mg a.i./kg and a recommended 1.5-fold dose of 200mg a.i./kg,applied 3-4 times.The highest residues of fludioxonil in grapes and soil in2016-2017 were 2.19 mg/kg,1.05 mg/kg,and 4.90 mg/kg,1.47 mg/kg,respectively.Residues<2.00 mg/kg?less than 2 mg/kg MRL for the CAC?.Therefore,it is safe to apply 40%fludioxonil suspension on grapes 3 times at 133.3 mg a.i./kg?3000 times formulation?.