Conclusions

As shown above there are various means for separating the enantiomers of amino acids and their

Figure 4 The separation of the enantiomers of three A/-t-Boc-amino acids. The column used was 25-cm long packed with Cyclobond 1 RSP and operated at a mobile phase flow rate of 1.0mLmin~1 at a temperature of - 22u°C. The mobile phase was 7% v/v acetonitrile-93% v/v% buffer (1 % triethylamine, pH 7.1) and the separation was monitored with a UV detector at 225 nm. (Courtesy of San Chung Chang, Wang LR and Armstrong DW (1992) Facile resolution of A/-tert-butoxycarbonyl amino acids: the importance of enantiomeric purity in peptide synthesis, Journal ofLiquidChromatography 15: 1411-1429.)

Figure 4 The separation of the enantiomers of three A/-t-Boc-amino acids. The column used was 25-cm long packed with Cyclobond 1 RSP and operated at a mobile phase flow rate of 1.0mLmin~1 at a temperature of - 22u°C. The mobile phase was 7% v/v acetonitrile-93% v/v% buffer (1 % triethylamine, pH 7.1) and the separation was monitored with a UV detector at 225 nm. (Courtesy of San Chung Chang, Wang LR and Armstrong DW (1992) Facile resolution of A/-tert-butoxycarbonyl amino acids: the importance of enantiomeric purity in peptide synthesis, Journal ofLiquidChromatography 15: 1411-1429.)

derivatives. These range from indirect methods such as the formation of diastereoisomeric derivatives or direct methods that exploit the spatial characteristics of different enantiomers by making them interact with a chiral stationary or mobile phase. This selectively enhances the standard free entropy of distribution of one amino acid enantiomer compared to the other and can provide adequate chiral selectivity to permit enantiomeric resolution. By one or other of these approaches the separation of the enantiomers of the majority of naturally occurring amino acids can be achieved by liquid chromatography.

See also: N/Chromatography: Liquid: Derivatization. III/Chiral Separations: Capillary Electrophoresis; Cellulose and Cellulose Derived Phases; Chiral Derivatization; Countercurrent Chromatography; Crystallization; Cyc-lodextrins and Other Inclusion Complexation Approaches; Gas Chromatography; Ion-Pair Chromatography; Ligand Exchange Chromatography; Liquid Chromatography; Molecular Imprints as Stationary Phases; Protein Stationary Phases; Synthetic Multiple Interaction ('Pirkle') Stationary Phases; Supercritical Fluid Chromatography; Thin-Layer (Planar) Chromatography.

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