Residue and dissipation of cyhalodiamide in rice paddy

In the present work, a rapid, sensitive and efficient analytical method was developed for the determination of cyhalodiamide in rice paddy samples including paddy water, soil and rice straw, and accordingly the residue and dissipation of cyhalodiamide in the rice paddy were also investigated. Residues of cyhalodiamide were extracted and purified via a modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method and liquid-liquid extraction (LLE) and detected by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) using electrospray ionization in positive mode. Average recoveries for residues of cyhalodiamide in paddy water, soil and rice straw were acquired as 70%-101%, with the relative standard deviation (RSD) from 0.7% to 9.1% and the minimum detectable concentration of 0.002, 0.005 and 0.01 mg/kg, respectively, which illustrates the favorable applicability of this optimized method and indicates that the accuracy can meet the demand for the sensitive detection of cyhalodiamide in the rice paddy. Through the field trial, kinetics of residual cyhalodiamide in paddy water, soil and rice plant were found to be in accordance with the first-order rate equation with the half-lives of 4.8-7.7 d, 5.2-8.3 d and 1.5-15.4 d, respectively, which suggests that cyhalodiamide is an easily degradable compound in the environment.