Determination of tetracycline residues in potatoes and soil by LC-MS/MS: Method development, validation, and risk assessment

A method utilizing liquid-liquid extraction (LLE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated according to the Commission Implementing Regulation (CIR) EU 2021/808 for quantifying four tetracyclines (TCs) in potatoes and soil. The method demonstrated recovery values ranging from 70 to 121% and precision (repeatability and within-laboratory reproducibility), with coefficient of variation (CV) values below 18% for all TCs in both matrices. The limits of quantification (LOQs) for the TCs ranged from 0.90 to 1.87 μg/kg in potatoes and from 0.68 to 1.25 μg/kg in soil. The decision limit (CCα) and detection capability (CCβ) ranged from 10.4 to 12.3 μg/kg and 11.9 to 14.3 μg/kg, respectively. Analysis of 538 potato and soil samples from Egyptian farms revealed a 13.2% occurrence of TC residues, with a higher frequency in soil (19.33%) than in potatoes (7.06%). Target hazard quotient (THQ) values indicated that TC residues in potatoes do not pose a health risk to Egyptian consumers.