Simultaneous LC-MS/MS determination of diacylhydrazine ecdysone receptor agonist insecticides in tomatoes: field dissipation, household washing effects, and dietary risk assessment.

Tomato (Lycopersicon esculentum Mill.) is among the most widely cultivated vegetables worldwide, yet its production is vulnerable to insect pests, necessitating extensive insecticide use. In this study, a sensitive and robust LC-MS/MS method was developed and validated for the simultaneous determination of four insecticides-methoxyfenozide, tebufenozide, chromafenozide, and halofenozide-in tomato fruits. The method demonstrated excellent linearity (R 2 > 0.99), LOQ = 0.01 mg kg-1 for all analytes, mean recoveries 81.2-97.6%, and matrix effects between -18.7% and -4.7%, confirmed its reliability for routine residue surveillance. Given the global reliance on methoxyfenozide and tebufenozide, field dissipation studies were conducted using recommended and double recommended doses under open-field conditions in Egypt to assess their dissipation behavior, pre-harvest intervals (PHIs), and associated dietary risks. To support terminal-residue evaluation at harvest, samples were collected at 1, 3, and 7 days after the final application, coinciding with commercial harvest maturity. Both compounds followed first-order kinetics, with rapid dissipation reflected in half-lives ranging from 1.99 to 2.31 days and PHIs between 1.32 and 4.36 days, ensuring compliance with international maximum residue limits. Chronic dietary exposure, expressed as %ADI (RQ = NEDI/ADI × 100), was low: the maximum across all scenarios was 4.06% for methoxyfenozide and 39.44% for tebufenozide; thus, NEDI values were <100% of ADI in every case, indicating no chronic health concern. Furthermore, household processing methods-particularly washing with 5% acetic acid-significantly reduced residues by up to 83.87%, offering an accessible strategy for minimizing consumer exposure. These findings provide critical evidence to support the safe and sustainable use of insect growth regulators in tomato production while underscoring the value of simple post-harvest interventions to enhance food safety.