Terminal Residues and Risk Assessment of Spiromesifen and Spirodiclofen in Tomato Fruits

Insecticides are important to increase crop yields, but their overuse has damaged the environment and endangered human health. In this study, residues of spiromesifen and spirodiclofen were determined in tomato fruit using a simple and efficient analytical procedure based on acetonitrile extraction, extract dilution, and UPLC-MS/MS. The linearity range was 1-100 mu g/kg and 0.5-100 mu g/kg, and the correlation coefficient (R-2) and residuals were =0.9991 and =16.4%, respectively. The limit of determination (LOD) was 0.26 and 0.08 mu g/kg, while the limit of quantification (LOQ) was verified at 5 mu g/kg. The relative standard deviation of spiked replicates at 5 mu g/kg analyzed in one day (RSDr, n = 6) was =8.35%, and within three different days (RSDR, n = 18) it was=15.85%, with recoveries exceeding 91.34%. The method recovery test showed a satisfactory value of 89.23-97.22% with an RSD of less than 12.88%. The matrix effect was determined after a 4-fold dilution of the raw extract and was -9.8% and -7.2%, respectively. The validated method was used to study the dissipation behavior of the tested analytes in tomato fruit under field conditions. First-order kinetics best described the dissipation rates. The calculated half-lives were 1.49-1.83 and 1.91-2.38 days for spiromesifen and spirodiclofen, respectively, after application of the authorized and doubled authorized doses, indicating that spiromesifen dissipated more rapidly than spirodiclofen. The final residue concentrations of spiromesifen and spirodiclofen were 0.307-0.751 mg/kg and 0.101-0.398 mg/kg, respectively, after two or three applications, and were below the European Union (EU) maximum residue limits. The chronic risk assessment indicates that both insecticides are safe for adult consumers.

Automated summary

Insecticides are important for increasing crop yields, but excessive use has negative impacts on the environment and human health. This study developed a simple and efficient analytical method using acetonitrile extraction and UPLC-MS/MS to determine the residues of spiromesifen and spirodiclofen in tomato fruit. The method was validated with good linearity, LOD, LOQ, and recovery rates. The dissipation behavior of the insecticides in tomato fruit under field conditions was also studied, showing that spiromesifen dissipated more rapidly than spirodiclofen. The final residue concentrations were below the European Union maximum limits and the insecticides were deemed safe for adult consumers based on chronic risk assessment.