Study On The Residue Analysis And Digestion Of 30% Diphenyl Acyclozole Propionazole Pyrrrithione On Pepper

In current work, we developed a liquid chromatography coupled with tandem mass spectrometry(LC-MS/MS) method to determine the residues of 30% difenoconazole·propiconazole·pyraclostrobin(suspension concentrate, SC) in pepper matrix. And scientific basises for the safely use and residue detection of difenoconazole, propiconazole and pyraclostrobin in pepper matrix were carried out.Difenoconazole, propiconazole and pyraclostrobin in pepper samples were extracted with acetonitrile, after adding MgSO4 and NaCl salting out supernatant fluid, the solutions were evaporated to remove acetonitrile completely, purified by C18 after constant volume. The soil was extracted with methyl alcohol, separated by XDB-C18 column, then the residues of difenoconazole, propiconazole and pyraclostrobin were determined by LC-MS/MS.The results showed that the external standard curve showed a good linearity between 0.005 and 0.5 μg/mL with the correlation coefficient of 0.99. The recoveries were ranged from 70.65% to 106.90% with RSDs between 1.49% and 6.46%. The sensitivity, accuracy and precision of the method meet the requirements of pesticide residues analysis.The field trials of 30% difenoconazole·propiconazole·pyraclostrobin(SC) were performed in Guizhou, Tianjin and Hunan province during the agricultural season in 2013 and 2014. The residues of difenoconazole, propiconazole and pyraclostrobin in pepper and soil were carried out. The results indicated that the constituents of difenoconazole, propiconazole and pyraclostrobin are below the MRL in pepper(the MRLs of difenoconazole, propiconazole and pyraclostrobin were 0.3 mg/kg, 0.05 mg/kg and 0.5 mg/kg respectively). Moreover, different factors for influence for the degradation of difenoconazole, propiconazole and pyraclostrobin were also investigated. The results showed the microorganism, humidity and acidic environment in soil can promote degradation of difenoconazole, propiconazole and pyraclostrobin. The degradation rate of the Hunan soil is fastest, the Tianjin soil is slowest.