Determination of the enantiomers of alpha-amino acids and alpha-amino acid amides by high-performance liquid chromatography with a chiral mobile phase.
A high-performance liquid chromatographic method for the enantiomeric analysis of a mixture of an alpha-amino acid and the corresponding acid amide is described. Reversed-phase chromatography with copper(II) acetate and N,N-di-n-propyl-L-alanine in the mobile phase are used for the separation. For Val and Val-NH2, several parameters affecting retention and enantioselectivity were investigated. The results indicate that by manipulation of pH, ionic strength, temperature, concentration of CuII, N,N-di-n-propyl-L-alanine and ion-pairing reagent, good control of enantiomeric separation can be achieved. For alpha-amino acid amides a mechanism is proposed which may account for the retention and enantioselectivity. Examples of enantiomeric analysis of mixtures of alpha-amino acids and alpha-amino acid amides with aliphatic, aromatic and polar side-chains are given. The method can be used for the control of the enantiomeric purity of alpha-amino acids and the corresponding acid amides obtained by enantioselective synthesis.
Duchateau
A
A
DSM Research, Geleen, The Netherlands.
Crombach
M
M
Aussems
M
M
Bongers
J
J
D000577:Amides / Q000032:analysis*; D000596:Amino Acids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism; D013696:Temperature
D000577:Amides; D000596:Amino Acids