Separation of micrometer-size oxide particles by capillary zone electrophoresis

Abstract 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 Al 2 O 3 , Fe 3 O 4 and TiO 2 and of Al 2 O 3 , Fe 3 O 4 and Fe 2 O 3 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 Al 2 O 3 and UO 2 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