Liquid chromatography chiral separation

Abstract There are no particular differences between academic and industrial liquid chromatography chiral separations. In industry, throughput needs and time requirements force for a search for solutions, i.e., enantiomeric fiill separations, without time for additional investigations that could lead to an even better solution. The three-point interaction model is historically recalled and ehallenged. The... 

Mitchell CR, Armstrong DW. Cyclodextrin-based chiral stationary phases for liquid chromatography. Chiral Separations. Methods Mol. Biol. 2004 243 61-112. 

Sharp, V.S. et al.. Enantiomeric separation of dansyl amino acids using macrocyclic antibiotics as chiral mobile phase additives by narrow-bore high-performance liquid chromatography. Chirality, 16, 153, 2004. 

Armstrong, D.W., DeMond, W., and Czech, B.P., Separation of metallocene enantiomers by liquid chromatography chiral recognition via cyclodextrin bonded phases, Anal. Chem., 57, 481, 1985. 

The need for chiral high-performance liquid chromatography (HPLC) separation to upgrade the ee. 

Using the purified (S)-3-hydroxycarboxylate oxidoreductase (107) and two forms of NADPH regeneration led to the chiral 3-hydroxy carboxylates shown in Table 28 (83). All products of the bioreduction procedures showed ee values greater than 98 %. On the basis of the optical rotation value reported (108) the synthesized 3-hydroxybutyrate was the (5)-enantiomer. It was assmned that the configuration of the other prepared 3-hydroxycarboxylates was the same. As checked with racemic mixtures of the derivatives of the four 3-hydroxy acids mentioned in Table 28, the applied chiral gas/liquid chromatography columns separated the enantiomers. For details see (83). 

Caccamese, S. Direct high-performance liquid chromatography (HPLC) separation of etodolac enantiomers using chiral stationary phases. Chirality, 1993, 5, 164-167... 

D.W. Armstrong, W. DeMond, and B.P. Czech, Separation of Metallocene Enantiomers by Liquid Chromatography Chiral Recognition via Cyclodextrin Bonded Phases, Anal. Chem., 57(1985)481. 

A few reports are available on chiral separations of pollutants using this modality of liquid chromatography. The separated chiral pollutants are 2-(2-chlorophenoxy)propionic acid and 2-(4-chlorophenoxy)propionic acid on n-alkyl-)8-D-glucopyranoside [17], ibuprofens on vancomycin [18] and PCBs on y-cyclodextrin [19]. Marina etal. [20] reported chiral separations of polychlorinated biphenyls (PCBs) 45, 84, 88, 91, 95, 132, 136, 139, 149, 171, 183 and 196 by MEKC using cyclodextrin chiral selectors. Mixtures of and y-cyclodextrins were used as chiral modifiers in a 2-(yV-cyclohexylamino)ethanesulfonic acid (CHES) buffer containing urea and sodium dodecyl sulfate (SDS) micelles. A mixture of PCBs 45, 88, 91, 95, 136, 139, 149 and 196 was separated into all 16 enantiomers in an... 

Tan X, Hou S, Wang M (2007) Enantioselective and diastereoselective separation of synthetic pyrethroid insecticides on a novel chiral stationary phase by high-performance liquid chromatography. Chirality 19 574—580... 

The resolution of optically active compounds by gas chromatography with chiral phases is a well-established procedure, and the separation of Al-perfluoto-acetylated ammo acid ester enantiomers m 1967 was the first successful application of enantioselective gas-liquid chromatography [39] Ammo acids have been resolved as their A -trifluoroacetyl esters on chiral diamide phases such as N-lauroyl-L-valineferf-butylamideorAl-docosanoyl-L-valme /ez-r-butylamide [40,41,... 

Figure 11.3 Typical configuration for the on-line coupling of an achiral and chiral cliro-matograpliic system by means of a switching valve. The non-enantio-resolved solute is isolated on the achiral phase and then stereochemically separated on the chiral phase. Reprinted from G. Subramanian, A Practical Approach to Chiral Separation by Liquid Chromatography, 1994, pp. 357-396, with permission from Wiley-VCH.

T. A. G. Noctor, Bioanalytical applications of enantioselective high-performance liquid cliromatography in A Practical Approach to Chiral Separations by Liquid Chromatography, Subramanian G (Ed.), VCH, Weinheim, Ch. 12, pp. 357-396 (1994). 

HPLC separations are one of the most important fields in the preparative resolution of enantiomers. The instrumentation improvements and the increasing choice of commercially available chiral stationary phases (CSPs) are some of the main reasons for the present significance of chromatographic resolutions at large-scale by HPLC. Proof of this interest can be seen in several reviews, and many chapters have in the past few years dealt with preparative applications of HPLC in the resolution of chiral compounds [19-23]. However, liquid chromatography has the attribute of being a batch technique and therefore is not totally convenient for production-scale, where continuous techniques are preferred by far. 

B. Sellergren, Enantiomer separation using tailor-made phases prepared by molecular imprinting in A practical approach to chiral separations by liquid chromatography, G. Subramanian, VCH, Weinheim (1994) Chapter 4. 

Despite the difficulties caused by the rapidly expanding literature, the use of chiral stationary phases (CSPs) as the method of choice for analysis or preparation of enantiomers is today well established and has become almost routine. It results from the development of chiral chromatographic methods that more than 1000 chiral stationary phases exemplified by several thousands of enantiomer separations have been described for high-performance liquid chromatography (HPLC). 

The versatility of chiral stationary phases and its effecitve application in both analytical and large-scale enantioseparation has been discussed in the earlier book A Practical Approach to Chiral Separation by Liquid Chromatography" (Ed. G. Sub-ramanian, VCH 1994). This book aims to bring to the forefront the current development and sucessful application chiral separation techniques, thereby providing an insight to researchers, analytical and industrial chemists, allowing a choice of methodology from the entire spectrum of available techniques. 

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