High-performance liquid chromatography amino acid enantiomers

Desai,M.J., Armstrong, D.W. (2004). Analysis of native amino acid and peptide enantiomers by high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry. J. Mass. Spec. 39, 177-187. 

Ding, GS. etal.. Chiral separation of enantiomers of amino acid derivatives by high-performance liquid chromatography on a norvancomycin-bonded chiral stationary phase, Talanta, 62, 997, 2004. 

S. Allenmark, B. Bomgren, and H. Boren, Direct liquid chromatographic separation of enantiomers on immobilized protein stationary phases III. Optical resolution of a series of A-aroyl d, 1-amino acids by high-performance liquid chromatography onbovine serum albumin covalently bound to silica, /. Chromatogr. 264 (1983), 63-68. 

Horikawa, R. Sakamoto, H. Tanimura, T. Separation of a-hydroxy acid enantiomers by high performance liquid chromatography using copper (ii)-L-amino acid eluent. J. Liq. Chromatogr. 1986, 9 (4), 537-549. 

Hofstetter, H. Effect of the mobile phase on antibody-based enantiomer separations of amino acids in high-performance liquid chromatography,... 

R. H. Buck and K. Krummen, Resolution of amino acid enantiomers by high-performance liquid chromatography using automated pre-column derivatization with a chiral reagent, /. Chromatogr., A, 1984, 315, 279-285. 

Most amino acids have a chiral center at the alpha position, resulting in L- and D-enantiomers. High-performance liquid chromatography is the most widely used technique for the separation of amino acid enantiomers. For that purpose, various chiral deiivatizing reagents and chiral stationary phases are frequently used. The following topics are t)rpical examples of the LC separation and determination of amino acid enantiomers. 

Enantiomers can be separated by high-performance liquid chromatography in which the column material, or matrix, is covalently bonded to a chiral ligand. In this case, the chiral ligand is (5)-aspartic acid, an inexpensive, readily available amino acid. At pH 7, the carboxylic acid group of aspartic acid exists as its conjugate base, a carboxylate anion. The amino group is bonded to the column matrix. 

The Cahn-Mangold-Prelog (R,S) system was used here to describe the chirality of molecules, and the enantiomeric excess (e.e.) to quantify the enantiomeric purity. The e.e. values, which are usually obtained from direct concentration determinations by high-performance liquid chromatography (HPLC) or gas chromatography (GC), have replaced the operational term optical purity in the last decades due to a high sensitivity of optical rotations to experimental conditions [17]. However, e.e. values that were calculated in several cases from the optical rotation and the dl system of a-amino acids based on the optical rotation were also adopted from the literature. On the other hand, neither the directions in which enantiomers rotated plane-polarized light (+ or —) nor specific rotations a were stated here. 

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