Residue Analysis And Digestion Dynamics Study Of 20% Dinotefuran Effervescent Tablets On Rice

In this paper, a HPLC method was devepled to determine the residues of dinotefuran in paddy water, rice stem, soil, hull and brown rice. Paddy water was extracted by ethyl acetate and acetone(1:1, V/V), soil, hull and brown rice was extracted by acetonitrile, determined with HPLC. Rice stem was extracted by acetonitrile, purified with saturated salt water. The results turned out that the external standard curve has a good linearity in the concentration range of 1-100 ?g/mL with the correlation coefficient of 0.9999. The limits of detection(LOD) was 1.5×10-5 g and quantification(LOQs) of paddy water, rice stem, soil, hull and brown rice were between 0.05 mg/kg and 0.20 mg/kg. The spiked levels of dinotefuran in paddy water was between 0.05 and 2.5 mg/kg, in soil and brown rice was between 0.1 and 10mg/kg, and in rice stem and hull was between 0.2 and 20 mg/kg. The recoveries were ranged from 77.06 to 99.20%, which RSDs were between 0.98 and 8.23%. The method was suitable for detecting dinotefuran in rice matrices. In order to establish a variety of methods for the detection of rice dinotefuran residue, the optimization of pretreatment and rapid detection method were carried out. A LC-MS/MS method was used to detect dinotefuran residue in paddy soil, rice stem, hull and brown rice. The above five kinds of matrix samples were pretreated with a better QuEChERS method,then determined by LC-MS/MS, rice stem and hull were cleaned up with PSA and C18. LOD was 1.75×10-12 g and LOQ was 5.84×10-12 g, which met the requirements for pesticide analysis.The field trials of dinotefuran(effervescent tablets, 20%) were performed in Guizhou, Guangxi and Heilongjiang province during the agricultural season in 2014.The results showed that the MRL of pymetrozine was below 0.1 mg/kg at harvest time(the high dosage was 900 g/ha and low dosage was 600 g/ha, both dosages were applied 3-4 times), which was much lower than MRL of Japan(2 mg/kg). Therefore,20% dinotefuran effervescent tablets could applied safely on rice with the recommended dosage.