Design of useful methods for separation and analysis based on ion association reactions

Abstract

Methods for the separation and analysis of ionic and nonionic species based on ion association reactions were developed. A concept for ion association reactions and ion association reagents was proposed. The ion association reactions may be divided into two categories: an electrostatic interaction-induced ion association and a hydrophobic interaction-induced ion association. The latter ion association reaction has been often used in solvent extraction procedures. The effect of extraction solvents on the extractability of ion association complexes was examined: the differences in the extraction constant (log Kex) between two extraction solvents were almost equal in various ion association complexes. The difference in log Kex between the standard solvent (carbontetrachloride) and a given solvent may be defined as Sex: a parameter for the extraction ability of a solvent for an ion association complex. The extraction constant was divided into two parameters, C and A, assigned to the cation and anion; thus log KrK = C + A. A method for estimating C and A was proposed. By using log Kex predicted or experimentally obtained, novel solvent extraction/ spectrophotometrical methods were designed and used in practical analysis, for example, in the determination of anionic surfactants, alkaline metals and other metal ions, phosphorus, arsenic and silicon, boron, and organic ionic species. Applications of ion association reactions to analytical use in an aqueous medium were developed. One was based on the solubilization of ion association complexes, and the other on the micelle extraction of ion association complexes. Chromatographic separations and determination of chelate anions were also mentioned. © 1989, The Japan Society for Analytical Chemistry. All rights reserved.