The flow rate of the mobile phase was maintained at 1.5 mL/
min. The sample injection volume was 10 lL, and the temperature
of the column was controlled at 30 C. The mobile phase A contained 0.1 mol/L ammonium acetate aqueous solution (pH 7.5, adjusted by 10 mol/L sodium hydroxide). Mobile phase B contained
methanol–acetonitrile (30:70, v/v). The gradient conditions were
5%–50% B (0–20 min) followed by 50%–5% B (20–30 min). The
detection wavelength was set at 430 nm for the determination of
TAR and 510 nm for the other colourants. The HPLC chromatograms of the post-extraction mixed food colourant standard solutions are shown in Fig. 1.