A novel immobilization of crown ethers on the surface of porous materials and their application in the separation of sodium and potassium

Liquid chromatography of alkali and alkaline-earth metal ions using octadecylsilanized silica columns modified in situ with lipophilic crown ethers

“…Extensive studies about use of crown ethers in liquid chromatography of cationic species, especially, alkali and alkaline-earth metal ions, have been made so far. In most cases polymeric crown ether resins (1)(2)(3)(4)(5)(6) and silica gels on which crown ether moieties are immobilized through covalent bonding (7-10) or which are coated with polymeric crown ether (11,12) have been applied to the stationary phases for the ion chromatography. The crown ether stationary phases are quite different in chromatographic behavior from conventional "ionic" cation exchangers.…”

“…The use of complexes formed between chiral ligands and metal ions to perform chromatographic separations and analyses of amino acid enantiomers has attracted considerable attention in recent years (1). One approach has been to covalently bond a chiral ligand to the solid support of the chromatographic column (2)(3)(4)(5). Another has been to add a chiral ligand and metal ion to the eluant phase (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18).…”