Adsorption of Synthetic Dyes Under the Conditions of Capillary Zone Electrophoresis

The migration and accompanying adsorption of the synthetic anionic food dyes Yellow Sunset FCF (E110) and Green Fast FCF (E143) in a fused silica capillary are studied by capillary zone electrophoresis. The adsorption of dyes is quantitatively estimated from the dependence of electrophoretic mobility μ ep on the dye concentration in a sample. We find that the electrophoretic mobility of E143 dye reaches a maximum at a low concentration, and that of the E110 dye reaches a maximum at an even lower concentration because the E143 molecule is larger and more hydrophilic. The dependence of μ ep on the concentration of Green Fast FCF in a sample is compared with the isotherm of adsorption of this dye on Silokhrom S-80 silica gel. The maximum adsorption capacity of silica gel for E143 is 6 × 10 –4 μM/m 2 .