Controlled changes in selectivity of cation separations by capillary electrophoresis using various crown-ether additives

This paper investigates how the concentration and type of crown ether affects the separation of cations and how one can optimize the concentration of the crown ether to achieve the best separation. An electrolyte consisting of 1.0 mM UV Cat-2, 3.0 mM tropolone, and 3.5 mM 18-crown-6 was found to provide the best separation for all cations investigated. Use of this optimized electrolyte was applied to the analysis of low levels of potassium in technical grade ammonium tungstate used in the electronics industry.