Nitrofurans are banned veterinary medicinal products due to their carcinogenic and mutagenic properties; however, their protein-bound metabolites (AOZ, AMOZ, AHD, SEM, and DNSAH) may persist in food-producing animals, particularly in eggs. Reliable confirmatory methods are therefore essential for residue monitoring under the stringent requirements of Commission Implementing Regulation (EU) 2021/808. This study reports the development and validation of a sensitive and selective LC–MS/MS method combining acid hydrolysis, 2-nitrobenzaldehyde derivatization, and QuEChERS extraction for the determination of nitrofuran metabolites in eggs. Chromatographic separation was carried out using a phenyl-hexyl column, and detection using a tandem mass spectrometer, supported by isotope-labeled internal standards, ensured robust identification and quantification. Linearity was satisfactory over the investigated concentration range (R2 > 0.99), with recoveries between 82 and 109%. The method’s precision was acceptable, with repeatability RSD values below 10% and within-laboratory reproducibility RSD values below 22%. Matrix effects were effectively controlled, remaining within ±20% following internal standard normalization. Decision limits (CCα) ranged from 0.29 to 0.37 µg/kg, well below the EU reference point for action of 0.5 µg/kg. The method’s performance was further confirmed through participation in an accredited proficiency test scheme. Overall, the validated method provides a reliable analytical tool for routine official control laboratories, enabling the sensitive confirmatory detection of banned nitrofuran residues in eggs and supporting food safety and regulatory compliance.
Marku et al. (Tue,) studied this question.