Reversed-phase thin-layer chromatography of some foodstuff dyes

The chromatographic behavior of nine frequently used water-soluble food dyes has been studied by TLC on RP-18 silica gel. Reversed-phase chromatographic separations were performed with mobile phases containing ammonium sulfate and water with ethanol or acetone as organic modifiers. The effect of mobile phase composition on retention, and the selectivity of the chromatographic systems, are discussed, and on the basis of the results obtained separation mechanisms are proposed. It was established that ammonium sulfate as a component of the mobile phase significantly increased the reversed-phase behavior of the chromatographic systems used.