HPLC Determination of 11 Synthetic Colorants and Their Aluminum Lakes in Food

The oil in the food sample (about 2.0 g) was removed with 20 mL of petroleum ether by oscillation for 1.0 min. 0.1 mol·L^-1 sodium hydroxide solution was used as solution for 11 synthetic colorants and their aluminum lakes. HPLC was applied to the determination of 11 synthetic colorants and their aluminum lakes in the sample solution. Waters XBridge-C₁₈ chromatographic column was used as separation column with mixtures of 0.02 mol·L^-1 ammonium acetate solution and methanol with different mixing ratios as mobile phase in the gradient elution, and photodiode array detector was used for determination. Linear relationships between values of instrument response and mass concentration of 11 synthetic colorants and their aluminum lakes were kept in the same range of 0.2-5.0 mg·L^-1, with same lower limit of determination (10S/N) of 0.5 mg·kg^-1. On the base of blank food sample, test for recovery was made by standard addition method; values of recovery found were in the range of 61.0%-115%, with RSDs (n=6) of determined values in the range of 0.50%-13%.