State-of-the-art enantioseparations of natural and unnatural amino acids by high-performance liquid chromatography

• The state of the art of the enantioselective amino acid analysis by HPLC is presented.
• Chiral stationary phases for the resolution of free and tagged amino acids are shown.
• We aimed to provide an overview on technical and practical solutions also.
• Insights on molecular recognition processes have been integrated.

This review discusses recent publications on the separation and analysis of natural and unnatural amino acid enantiomers by liquid chromatography. Focus is placed on methodological aspects relating chiral stationary phases and chiral columns which can cope with the challenge. Conceptually, amino acids can be enantioseparated in free form, which refers to the resolution of polar ampholytes, or as N-protected amino acids, which can be regarded as acidic commodities. Such synthons are used, for instance, in peptide synthesis protocols. Amino groups are frequently tagged with highly fluorescent or MS/MS active labels in order to generate sensitive and simultaneously stereoselective assays of diverse amino acids in complex matrices.It is our intention to present the state of the art of enantioselective amino acid analysis by HPLC concepts and to pinpoint practical aspects.