Chromatographic selectivity for amino acid esters and alkali metal ions on a silica bonded calix[4]arene tetraester stationary phase

Abstract

A silica bonded tetrameric calix[4]arene ester stationary phase has been used in the chromatographic separation of alkali metal ions and amino acid esters. Under reversed phase conditions, baseline resolution of a standard test mixture of benzamide, benzophenone and biphenyl was achieved using an MeOH—H₂O mobile phase. In the chromatography of the amino acid ester hydrochlorides, retention appears to be related to the hydrophobicity of the esters studied, with tryptophan methyl ester being the longest retained.