Application of TLC, HPLC and GC methods to the study of amino acid and peptide enantiomers: a review

Amino acids are very important organic compounds in nature. The biological activity of amino acids depends mainly on their stereoisomeric configuration (d- or l-). Thus, the stereochemical analysis of amino acids and peptides is an important aspect of their characterization. Owing to the increasing role of amino acid configuration in biomedical and pharmaceutical studies, numerous analytical methods have been described in the literature. Among a wide range of analytical techniques available for the steroselective separation of different amino acids, which were obtained from plants or biological samples, chromatographic methods such as thin-layer chromatography, high-performance chromatography and also gas chromatography are very useful. This review presents such systems developed for direct stereoisomeric separation and quantitative determination of amino acid and peptide enantiomers with emphasis on selected literature published during two last decades. Almost all aspects, including sample preparation prior chromatographic analysis, stationary phase, solvent system and detection system, are discussed. New possibilities in chiral amino acid analysis have been opened up by the application of mass spectrometry and infrared detection in thin-layer chromatography and mass spectrometry-selected ion monitoring detection system in gas chromatography. A modern trend in high-performance chromatography is two-dimensional chromatography. These innovations have led to decreased development time and increased amino acid resolution and detectability.