- Article
Development and Validation of a Confirmatory LC-MS/MS Method Using QuEChERS for Determination of Nitrofuran Metabolites in Eggs According to EU Regulation 2021/808
- Elmira Marku,
- Kozeta Vaso and
- Ilir Ajdini
- + 5 authors
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.
17 February 2026





![(a) Analyte peak of AOZ (positive mode) in negative control [black—quantifier transition; blue and green—quantifier transitions]. (b) Analyte peak for AOZ (positive mode) spiked at 0.2 μg/kg. (c) Analyte peak of DNSAH (negative mode) in negative control [black-quantifier transition; blue and green–quantifier transitions]. (d) Analyte peak for DNSAH (negative mode) spiked at 0.2 μg/kg. Notes: Quantifier transition: used to determine analyte concentration. Qualifier transitions: used to confirm analyte identity. X-axis: retention time (min), Y-axis: relative response. In the upper side of the picture and in the lower side of the picture, the chromatogram of the internal standard is shown.](https://mdpi-res.com/cdn-cgi/image/w=470,h=317/https://mdpi-res.com/molecules/molecules-31-00700/article_deploy/html/images/molecules-31-00700-g001a-550.jpg)




