Preparative chromatographic separation of amino acid racemic mixtures: I. Adsorption isotherms

Commercially available RP-18 chromatographic column is impregnated with the chiral selector N-hexadecyl-l-hydroxyproline used for the racemic separation of the amino acids: dl-phenylalanine, dl-valine, dl-proline, dl-tyrosine, dl-leucine, dl-tryptophane, dl-methionine, dl-arginine and dl-histidine. The separation efficiency and the stability of the impregnated chromatographic column is studied and compared with literature data. The capacity factors and the enantioselectivities of those amino acids are experimentally determined and the separation behaviour is discussed. The frontal analysis (adsorption and desorption) and the perturbation method are used for the estimation of the adsorption isotherms. Their limit of applicability is given for each amino acid and the adsorption isotherm is modelled using the multi-component competitive Langmuir equation.