Simultaneous Determination of 6 Industrial Dyes in Foods by Solid Phase Extraction-Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

An ultra high performance liquid chromatography-tandem mass spectrometric method was established for the simultaneous determination of the residues of six industrial dyes in foods. The samples were extracted with 50 mmol/L ammonium acetate solution containing 50% methanol and 1% formic acid, cleaned up by WAX solid phase extraction column, and then analyzed in multiple reaction monitoring (MRM) mode. Sample matrix-matched calibration was used to determine the residue contents by external standard. Orange II was detected with negative ion model, and the other five dyes were detected with positive ion model. Limit of quantitation (LOQ) of Chrysoidine II, Rhodamine B, Auramine O, Rhodamine 6G and Safranine T was 1.6 mu g/kg, and LOQ of orange II was 6.0 mu g/kg. The linear range of chrysoidine II, rhodamine B, auramine O, rhodamine 6G and safranine T was 1.0-100.0 mu g/L and that of orange II was 5.0-100.0 mu g/L, the linear correlation coefficients were all more than 0.999. The recoveries of 6 dyes ranged from 70.3% to 109.2% with relative standard deviations (RSD) of 2.6%-14.1%. This method was simple, effective and sensitive, and was suitable for the determination and confirmation of six industrial dyes added in the foods illegally.