Study On Residual Analysis And Digestion Of 62% Azoxystrobin Ketone Nitrile Water - Dispersible Granules On Grape

In current work, a modified QuEChERS pretreatment method with(GC-NPD) to determine the residues of cyprodinil and fludioxonil in grape and soil in grape and soil was developed, a basic research to residue and degradation of cyprodinil and fludioxonil in grape and soil was carried out, it is able to provide a scientific basis for the safly use and residue determination of cyprodinil and fludioxonil in grape matrix.The soil sample was extracted with acetonitrile(1% acetic acid), then vortexed and centrifuged, one half of solutions were evaporated to remove acetonitrile completely,followed by purifying samples with dispersive soild-phase extraction. Then the residue of cyprodinil and fludioxonil was determined by GC-NPD. The grape sample was extracted with acetonitrile(1% acetic acid), then vortexed, centrifuged, and added sodium acetate, the result solutions were filtered by anhydrous sodium sulfate( the middle of anhydrous sodium sulfate was filled by silica gel about 1 mm), one half of filtrate were evaporated to remove solutions completely, followed by purifying samples with dispersive soild-phase extraction. Then the residue of cyprodinil and fludioxonil was determined by GC-NPD. Cyprodinil and fludioxonil were completely separated from impurities at 18.6 min. The results showed that the external cyprodinil standard curve showed a good linearity between 0.200 and 100 μg/mL with the correlation coefficient of 0.9997. The limit of detection was 6.67×10-11 g and the limit of quantification was 5.00×10-2 mg/kg. The spiked levels of cyprodinil were from5.00×10-2 to 10.0 mg/kg in soil and grape. The recoveries of cypprodinil were ranged from 89.08 to 108.8% with RSDs between 1.8 and 5.3%. The external fludioxonil standard curve showed a good linearity between 0.400 and 100 μg/mL with the correlation coefficient of 0.9998. The limit of detection was 1.34×10-10 g and the limit of quantification was 1.00×10-1 mg/kg. The spiked levels of cyprodinil were from1.00×10-1 to 10.0 mg/kg in soil and grape. The recoveries of cypprodinil were ranged from 75.80 to 104.0% with RSDs between 1.9 and 7.1%. The method was suitable for cyprodinil and fludioxonil determination in grape and soil matrix.The field trials of 62% cyprodinil and fludioxonil(water dispersible granule)were performed in Guizhou and Anhui province during the agricultural season in 2013 and 2014, and the residues of cyprodinil and fludioxonil in grape and soil were determined. The results showed that the residues of cyprodinil in grape were lower than 3.00 mg/kg(the MRL of cyprodinil was established by CAC is 3 mg/kg) at 14 days after the last spraying for the dosage of 750 g a.i./ha was applied three times.The residues of fludioxonil in grape were lower than 2.00 mg/kg(the MRL of cyprodinil was established by CAC is 2 mg/kg) at 14 days after the last spraying for two dosages. Therefore, the formulation, a water dispersible granule(WG) containing62% cyprodinil and fludioxonil is applied on grape three times according to the recommendation of manufacturer is safe.In addition, it is the first time that the modified QuEChERS method with GC-NPD was established and applied to the study on residue analysis and degradation dynamics of cyprodinil and fludioxonil in grape matrix. What’s more, the factors to influence degradation of cyprodinil and fludioxonil in soil were researched firstly,learned the rules about degradation of cyprodinil and fludioxonil in soil and evaluated potential risk of cyprodinil and fludioxonil to environment.