| In this study, the analytical methods of flubendiamide was studied. We monitored the residues and kinetic of flubendiamide in corn. From monitoring these, we can provide the basis for the flubendiamide using in field, provide the basis for the establishment of MRL and evaluate the dietary risk though the changing residual flubendiamide in corn. The results were summarized as follows:1. A HPLC method for determination of flubendiamide SC was established. The chromatographic conditions were systematically investigated with C18 column as the stationary phase, the mixture of methanol and acetic acid as the mobile phase at 235 nm. The linear correlation coefficient was 0.9992 in 10~500 mg/L. The average recoveries was 102.31%. In addition, the standard deviations was 0.033, the variation coefficients was 0.33%. The method has the advantage of simple, good linear relationship, high precision and accuracy, which is suitable for quantitative analysis.2. A HPLC method and LC-MS method were established to evaluate residual dynamics of the flubendiamide in corn plant, soil and corn samples. The flubendiamide could be extracted with acetone, purified with florisil. In the HPLC method validation, the chromatographic conditions were systematically investigated with C18 column as the stationary phase, the mixture of methanol and acetic acid as the mobile phase at 235 nm. The correlation codfficients was 0.9996 with the linear ranging from 0.02 to 5 mg/L. At the fortification levels of 0.02, 0.05, 0.5 mg/kg, average recoveries in corn plant, soil, green corn and corn were 83.4~96.0%, 96.4~98.4%, 72.8~105.0% and 75.5~86.4%, respectively. And the relative satandard deviations were 5.7~11.0%,1.2~3.2%,0.3~2.4% and 0.9~10.3%, respectively. In the LC-MS method, m/z 704.9/530.4 and 704.9/255.8 were used for qualitation and 704.9/530.4 was used for quantification, the mixture of acetonitrile and methanoic acid as the mobile phase. The correlation codfficients was 0.9941 with the linear ranging from 0.005 to 0.2 mg/L. At the fortification levels of 0.02, 0.05, 0.5 mg/kg, average recoveries in corn plant, soil, green corn and corn were 77.5~92.7%,89.7~97.7%,93.5~94.6% and 87.8~94.3%, respectively. And the relative satandard deviations were 2.1~7.1%,0.6~2.2%, 1.5~9.9% and 2.7~8.6%, respectively. The sensitivity, average recoveries and relative satandard deviations of the two methods well satisfied the essential rules of pesticide residue determination.3. The field trials of 10% flubendiamide SC in corn were performed in Heilongjiang and Shandong from 2014 to 2015. The results showed that the half-lives of flubendiamide were 0.03 to 7.5 days in corn plant, and 4.2 to 5.6 days in soil. The result showed that flubendiamide was degraded easily in corn.4. 10% flubendiamide SC was sprayed at 450g/ha(45g a.i./ha) and 675g/ha(67.5g a.i./ha) on fields. Flubendiamide was sprayed 1 and 2 times with 7 days interval. The treated samples were collected from each plot on days 14 and 21 after the last application. The flubendiamide residues were from 2.521 to 4.760 mg/kg in corn plant, from 0.381 to 3.302 mg/kg in soil, and the flubendiamide in green corn and corn were below 0.02 mg/kg.5. The results suggest that the use of the flubendiamide on corn at an application rate of 450g/ha(45g a.i./ha) with 1 applications, and with a 21-day PHI is considered to be safe.6. The results suggest that the MRL of flubendiamide in corn is established at 0.02 mg/kg, temporarily. |
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