The mobile phase consisted of eluent A, ammonium acetate 1%
(pH 7.0, adjusted with ammonium hydroxide); and eluent B,
methanol:acetonitrile (80:20). The gradient elution program is
shown in Table 1. The injection volume was 20 lL. The flow rate
was 1.2 mL min1, the column temperature was maintained
between 38–40 C and the mobile phase was passed through
0.45 lm membrane filter. The food colorants were determined at
427–624 nm.