Separation of micrometer-size oxide particles by capillary zone electrophoresis

High quality separations of three-component mixtures of suspended micrometer-size metal oxide particles have been achieved by capillary zone electrophoresis in two different high-pH aqueous buffer systems. Mixtures of Al2O3, Fe3O4 and TiO2 and of Al2O3, Fe3O4 and Fe2O3 were separated in 5-10 min in either carbonate buffer, pH 10.6 or pyrophosphate buffer, pH 10.2. The effects of electric field strength, buffer concentration and buffer type on separation quality were determined. Under optimized conditions, the separations were nearly baseline resolved. Complete separation of a mixture of Al2O3 and UO2 particles was also accomplished. Different sized particles/aggregates of a given oxide were found to co-migrate so that, for the systems studied, particle size effects were negligible and the separations were electrophoretic in nature. Reproducibilities of migration times and peak widths, heights and shapes were found to be excellent, with relative standard deviations of migration times consistently being <1%. Published by Elsevier Science B.V.