Residues of the Acaricides Abamectin, Hexythiazox, and Spiromesifen in Eggplant (<i>Solanum melongena</i> L.) Fruits Grown under Field Conditions in Najran, Saudi Arabia

Abstract

The dissipation profiles of the acaricides abamectin, hexythiazox, and spiromesifen in the fruits of eggplant (Solanum melongena L.) grown under field conditions in Najran, Saudi Arabia, were studied. Extraction was performed with acetonitrile, and UPLC-MS/MS was used for quantification. Instead of conventional adsorbents, a 2-fold dilution of the sample extract quickly and efficiently reduced interfering co-extracts and matrix effects. The method was successfully validated according to EU regulations. The limit of quantification was set at 5 µg/kg for hexythiazox and spiromesifen and 20 µg/kg for abamectin. The mean recoveries and relative standard deviations were 88.6–98.7% and 5.2–12.4%, respectively. The method precision was evaluated at the LOQ level for each analyte and ranged from 6.7 to 15.7%, with good trueness (recovery) ranging from 85.7 to 97.2%. The matrix effect ranged from −2.2% to −4.6%, indicating negligible signal suppression. First-order kinetics were used to characterize the dissipation rates of abamectin, hexythiazox, and spiromesifen with half-lives (t1/2) of 2.11–2.42, 2.3–2.73, and 1.31–1.47 days, respectively, using the authorized and double authorized doses. Terminal residues were 0.028–0.331 mg/kg, 0.019–0.592 mg/kg, and 0.044–0.408 mg/kg, respectively, at 3, 7, and 10 days after the second treatment. According to the risk assessment results, the percentage of chronic dietary risk quotient was <100, meaning that abamectin, hexythiazox, and spiromesifen are not considered a risk to human health. The preharvest interval (PHI) should be 7, 7, and 3 days, respectively, if the authorized dose is used, and 10, 10, and 3 days, respectively, if double the authorized dose is used. The current study can be a helpful resource for the responsible and safe use of the tested acaricides on eggplant fruits.

Keywords

• insecticides
• terminal residues
• dissipation kinetics
• LC-MS/MS
• method validation
• risk assessment