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 microg kg(-1) in eggs, respectively. Identification and confirmation could be validated in the range of 2.0-4.2 microg 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.