Determination of nitrofuran metabolites in sausage casings and crawfish using LC-Q-Orbitrap HRMS: Method development and validation

This study developed and validated an analytical method for determining four nitrofuran (NF) metabolites in sausage casings and crawfish matrices. The method utilizes liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry (LC-Q-Orbitrap HRMS) to analyze these metabolites. The validation of the developed method was carried out in accordance with the Commission Implementing Regulation (CIR) EU 2021/808, using three concentration levels ranging from 0.25 to 0.75 μg/kg. The recoveries ranged from 77 % to 109 %, while both repeatability and reproducibility remained consistently below 15 %. The calibration curves exhibited good linearity, with correlation coefficients (R) exceeding 0.9978. The limits of detection (LOD) ranged from 0.0218 to 0.0596 μg/kg, while the limits of quantification (LOQ) ranged from 0.0719 to 0.1966 μg/kg. The decision limit (CCα) and detection capability (CCβ) values ranged from 0.30 to 0.39 μg/kg and 0.29–0.35 μg/kg, respectively. Out of 30 crawfish samples collected from local markets in Egypt, 16.66 % contained NF metabolites residues, whereas sausage casings showed no NF metabolite residues. The reliability of the method was further demonstrated through successful participation in two proficiency testing (PT) rounds.