[Determination of indigo and brilliant blue in different types of food products by high performance liquid chromatography with solid phase extraction].

Objective: To develop and validate a solid phase extraction-high performance liquid chromatographic( SPE-HPLC) method for the simultaneous determination of indigo and brilliant blue in different types of food products.

Methods: The artificial colors in food products were extracted by acetonitrile / water and purified by WAX SPE cartridges, The separation was achieved using a Waters Symmetry C_(18)( 5 μm, 4. 6 mm × 250 mm) column and a binary gradient mobile phase of methanol and 0. 02 mol/L ammonium acetate solution, detected by HPLC-PDA.

Results: The validated analytical method showed that there was a good linearity in the range of 0. 05- 20. 00 μg/mL for both indigo and brilliant blue( r > 0. 999). The lowest detection limits of indigo and brilliant blue were 0. 04 and 0. 02 mg/kg, respectively. The average recoveries were among 81. 8%- 101. 1%, with relative standard deviation( RSD) of 2. 1%- 4. 9%( n =6) for both artificial colors.

Conclusion: The method has high selectivity, high sensitivity, good recovery and reproducibility. It is suitable to simultaneously monitor indigo and brilliant blue in several types of food products based on the food classification system of GB 2760-2014.