Determination of Sudan dye residues in eggs by liquid chromatography and gas chromatography–mass spectrometry

A sensitive and cheap high performance liquid chromatography (HPLC) with ultraviolet-visible (UV-VIS) was developed for the determination of Sudan dyes (I, II, III, and IV) residues in various types of eggs. The chromatographic separation was achieved on a reverse phase C18 column with gradient elution, using a mobile phase of 0.1% formic acid acetonitrile/0.1% formic acid aqueous solution; detector was set at 478 nm for Sudan I and 520 nm for Sudan II, III and IV. The suspected egg samples were derivatized with N,O-bis (trimethylsilyl) trifluoro-acetamide and confirmed by gas chromatography–mass spectrometry (GC–MS) in EI. Mass spectra of trimethylsilyl derivatives of the Sudan dyes were built up in EI mode. Recoveries of the Sudan dyes ranged between 79.8 and 95.7% in eggs by HPLC–UV, with all the relative standard deviations of less than 5%. Limit of detection (LOD), limit of quantification (LOQ) were in the range of 4.0–4.8 and 12.3–13.8 μg kg−1 in eggs, respectively. Identification and confirmation could be validated in the range of 2.0–4.2 μg kg−1 with the GC–MS method. This method is suitable for routine fast monitoring, screening and confirmation of Sudan dyes residues in eggs, as mandated by regulatory agencies.