Application of chiral derivatizing agents in the high-performance liquid chromatographic separation of amino acid enantiomers: A review

The past 20 years has seen an explosive growth in the field of chirality, as illustrated by the rapid progress in the various facets of this intriguing field. The impetus for advances in chiral separation has been highest in the past decade and this still continues to be an area of high focus. This paper reviews indirect separation approaches, i.e. derivatization reactions aimed at creating the basis for the chromatographic resolution of biologically and pharmaceutically important enantiomers, with emphasis on the literature published in the last 12 years. The main aspects of the chiral derivatization of amino acids are discussed, i.e. derivatization on the amino group, transforming the molecules into covalently bonded diastereomeric derivatives through the use of homochiral derivatizing agents. The diastereomers formed (amides, urethanes, urea, thiourea derivatives, etc.) can be separated on achiral stationary phases. The applications are considered, and in some cases different derivatizing agents for the resolution of complex mixtures of proteinogenic d,l-amino acids, non-proteinogenic amino acids and peptides/amino acids from peptide syntheses or microorganisms are compared.