Effect of the mobile phase on the retention behaviour of optical isomers of carboxylic acids and amino acids in liquid chromatography on bonded Teicoplanin columns

Conditions for separation of enantiomers of underivatized amino acids phenyl glycine and tryptophan and of mandelic acid as test compounds were studied on a Chirobiotic T column packed with amphoteric glycopeptide Teicoplanin covalently bonded to the surface of silica gel. The effects of the mobile phase composition on the retention and selectivity under analytical conditions, on the profile of the adsorption isotherms of the enantiomers and on the overloaded separation were investigated. The concentration of ethanol or of methanol in aqueous–organic mobile phases and the pH of the mobile phase affect not only the retention and selectivity, the saturation capacity and the isotherm profile, but also the solubility of the acids, which should be taken into account in development of preparative separations. A compromise between the separation selectivity and the solubility should be made in selecting the mobile phase suitable to accomplish preparative separations at acceptable production rate and throughput of the operation.