Enantiomeric resolution of DNS‐amino acids by ligand exchange chromatography using l‐phenylalaninamide together with Cu(II) ions as chiral additives to the eluent

Resolution of various α‐DNS DL‐amino acids by ligand exchange chromatography of L‐phenylalaninamide–copper(II) complexes on a conventional reversed‐phase packing is reported. Parameters of the mobile phase which control retention and enantioselectivity such as concentration of Cu(II) ion and L phenylalaninamide (PheNH2), pH, ionic strength, and acetonitrile content were examined. In order to obtain further information on the distribution and stability of the prevailing complex species formed between the metal ion and the chiral selector, spectrophotometric measurements in different media were also carried out.