Determination of 20 synthetic dyes in chili powders and syrup-preserved fruits by liquid chromatography/tandem mass spectrometry

A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method is developed to simultaneously determine 20 synthetic dyes (New Coccine, Indigo Carmine, Erythrosine, Tartrazine, Sunset Yellow FCF, Fast Green FCF, Brilliant Blue FCF, Allura Red AC, Amaranth, Dimethyl Yellow, Fast Garnet GBC, Para Red, Sudan I, Sudan II, Sudan III, Sudan IV, Sudan Orange G, Sudan Red 7B, Sudan Red B, and Sudan Red G) in food samples. This method offers high sensitivity and selectivity through the selection of two fragment ion transitions under multiple reaction monitoring mode to satisfy the requirements of both quantitation and qualitation. Using LC-MS/MS, the newly developed extraction protocol used in this study is rapid and simple and does not require the use of solid-phase extraction cartridges. The linearities and recoveries of the method are observed at the concentration range of 0.10–200 μg/kg and more than 90% for all dyes, respectively. The method has been successfully applied to screen 18 commercial chili powders and six commercial syrup-preserved fruits purchased from retail establishments in Taipei City. The results show that three legal food dyes, Tartrazine, and/or Sunset Yellow FCF, and/or New Coccine, are present in some syrup-preserved fruits. Amaranth, an illegal food dye in certain countries but declared illegal in Taiwan, is found in an imported syrup-preserved fruit.