Simultaneous determination of 16 synthetic colorants in hotpot condiment by high performance liquid chromatography

A simultaneous determination method for 16 synthetic colorants in hotpot condiment was developed by high performance liquid chromatography. The samples were successively extracted with 2 mol/L carbamide solution containing 5% ammonia (dissolved in methanol) and methanol-acetone solution, and then the target analytes could be divided into two groups named as lipid-soluble and water-soluble colorants by ethyl acetate-cyclohexane with liquid-liquid extraction. The lipid-soluble and water-soluble colorants were purified by gel permeation chromatography and solid phase extraction column packed with polyamide resin, respectively. The obtained two eluates were combined, concentrated, and separated by C-18 column and determined by diode array detector. Good linear relationships between peak areas and the concentrations of the synthetic colorants were obtained in the range of 0.01-50.0 mg/L with correlation coefficients above 0.999 (n = 10). The limits of detection and quantitation were 1-3 and 10 mu g/kg for 16 synthetic colorants, respectively. The average recoveries at the spiked levels of 5, 10, 20 and 50 mu g/kg were in the range of 63.2-97.1% with relative standard deviations (n = 6) around 1.5-10.6%. This method is sensitive and reliable, and can be used to simultaneously determine 8 lipid-soluble and 8 water-soluble colorants in hotpot condiment. (C) 2014 Elsevier B.V. All rights reserved.