Abstract: A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of commonly abused dyes in candy, sirup, liquid milk and fruit juice. The test sample was dissolved and diluted with water, then cleaned up by polyamide solid phase extraction. The LC separation was performed on an Agilent XDB-C18 column with 20 mmol/L ammonium acetate solution and acetonitrile as the mobile phase in a gradient elution mode. The dyes were determined by MS/MS in negative electrospray ionization mode, and quantified by matrix-matched external standard method. The calibration curves showed good linearity in the range of 0.5~50 mg/L with the correlation coefficients (r) greater than 0.99. The limits of quantitation (S/N>10) were 0.5 mg/kg, and the limits of detection (S/N>3) were 0.1 mg/kg. The recoveries of dyes in food samples at the three spiked levels of 0.5, 5 and 50 mg/kg were in the range of 62.6%~115.3% with the relative standard deviations (RSDs) of 2.6%~26.3%. The method can meet the requirements for the determination of the dyes in food samples for import and export inspection.

Key words: dyes, food, liquid chromatography-tandem mass spectrometry (LC-MS/MS)