Determination of illegal dyes in eggs by liquid chromatography - tandem mass spectrometry

A multiresidue method for simultaneous determination of 10 dyes unauthorised for the use in laying hens was developed (Sudan I, Sudan II, Sudan III, Sudan IV, Sudan Red G, Sudan Orange G, Sudan Red 7B, Para-Red, Toluidine Red, Citrus Red). The dyes were extracted using liquid-liquid extraction with acetonitrile in the presence of anhydrous sodium sulphate, and cleaned using zirconium coated silica cartridges. After dilution with acetonitrile saturated with hexane:DMSO (8:2), samples were analysed using LC-MS/MS system with acetonitrile (A) and 0.1% formic acid (B) as a mobile phase in a gradient mode and C18 analytical column. The method was validated according to the requirements described in the Commission Decision 2002/657/EC: linearity (r ≥ 0.998), precision: repeatability (1.94%-10.02%), and within-laboratory reproducibility (4.66%-8.89%), recovery (97%-105%), decision limit CCα (5.33-6.50 μg/kg), and detection capability CCβ (6.18-7.50 μg/kg) were calculated. The developed method fulfilled all performance criteria and can be used in the official survey of dyes residues in food of animal origin.