A simple method to determine ten food colorants in a single
procedure is advantageous for routine analysis. Towards this, gradient
elution was tested to attain complete separation of the artificial
colorants. Three initial tests were evaluated using the
following: phosphate buffer (pH 6.0) and methanol; ammonium
acetate buffer (pH 6.5) and methanol; and 1% (m/v) ammonium
acetate solution at pH 6.0 and a mixture of methanol:acetonitrile
(80:20). The ammonium acetate buffer is known as a modifier for
the purification and separation of azo food colorants