Sub-minute separations of organic and inorganic anions with co-electroosmotic capillary electrophoresis

Abstract

Fast capillary electrophoretic separations of various classes of anionic compounds are performed by using very short effective separation lengths in addition to a similarly directed movement of the electroosmotic flow and the inherent electrophoretic mobilities of the analytes. A polycationic surfactant (hexadimethrine bromide) is added to the electrolyte, which dynamically coats the inner surface of the capillary and causes a fast anodic electroosmotic flow. Selective separations in the sub-minute range combined with high separation efficiencies of several hundred thousands theoretical plates per meter effective separation length can be achieved if organic solvents or mixtures thereof are added to the electrolytes. The methods are used for the high-speed separation of various anionic analytes, such as carbohydrates, carboxylic acids, phenolic compounds and inorganic anions.