Single phase extraction method for determination of dithianon residues in fruits and vegetables using LC ESI (-) MS/MS

Dithianon is a non-systemic fungicide, applied in some agricultural products. Dithianon residues in food cause health problems for humans so it is recommended to be analyzed in fruits and vegetables. Four different extracting solvents were compared to get the optimum one. Quantitative analysis was done using a liquid chromatography triple quadruple mass spectrometer in different agricultural products. The in-house validation process was carried out based on SANTE guideline. The results demonstrated an average recovery rate between 85 and 113%, with relative standard deviations (RSDs) ≤ 8% for all tested food matrices in repeatability and RSD_wR% = 16% in within-Laboratory reproducibility. Good linearity at r2 > 0.99 was obtained for 0.001-0.5 µg/ml dithianon calibration curves. Limit of quantifications (LOQs) for the method ranged between 0.01 and 0.05 µg/g with expanded measured uncertainty Uexp = ± 42%. Our method is simple, fast and reliable for the determination of dithianon residues in food so, it is recommended to be applied in the routine analysis. The method's practicality was confirmed by analyzing fifty market samples from Egypt. No dithianon residues were detected, a finding consistent with its limited national registration and underscoring the method's utility for ensuring compliance and food safety.