Chiral stationary phases enantioseparation

For enantioseparation chiral stationary phases (CSPs), an expression of the relative selectivity is obtained ... 

An alternative model has been proposed in which the chiral mobile-phase additive is thought to modify the conventional, achiral stationary phase in situ thus, dynamically generating a chiral stationary phase. In this case, the enantioseparation is governed by the differences in the association between the enantiomers and the chiral selector in the stationary phase. 

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. 

In this study, Ali and Aboul-Enein [80] used cellulose tr is (3,5-d ich Ioropheny 1 carbamate) chiral stationary phase for the enantioseparation of miconazole and other clinically used drugs by high performance liquid chromatography. The mobile... 

Petrusevska, K. et al.. Chromatographic enantioseparation of amino acids using a new chiral stationary phase based on a macrocyclic glycopeptide antibiotic, J. Sep. ScL, 29, 1447, 2006. 

Armstrong, D.W., Liu, Y., and Ekborg-Ott, K.H., A covalently bonded teico-planin chiral stationary phase for HPLC enantioseparations. Chirality, 7, 474, 1995. 

Aboul-Enein, H.Y and Ali, I., Optimization strategies for HPLC enantioseparation of racemic drugs using polysaccharides and macrocyclic antibiotic chiral stationary phases, II Farmaco, 57, 513, 2002. 

Rojkovieova, T. et al.. Study of the mechanism of enantioseparation. Vll. Effect of temperature on retention of some enantiomers of phenylcarbamic acid derivates on a teicoplanin aglycone chiral stationary phase, J. Liq. Chrom. Rel. TechnoL, 27, 1653, 2004. 

Sztojkov-lvanov, A. et al., Comparison of separation efficiency of macrocyclic glycopeptide-based chiral stationary phases for the LC enantioseparation of fi-amino acids, Chromatographia, 64, 89, 2006. 

Tesafova, E. and Bosikova, Z., Comparison of enantioseparation of selected benzodiazepine and phenothiazine derivatives on chiral stationary phases based on P-cyclodextrin and macrocyclic antibiotics, J. Sep. ScL, 26, 661, 2003. 

Enantioselective separation by supercritical fluid chromatography (SFC) has been a field of great progress since the first demonstration of a chiral separation by SFC in the 1980s. The unique properties of supercritical fluids make packed column SFC the most favorable choice for fast enantiomeric separation among all of the separation techniques. In this chapter, the effect of chiral stationary phases, modifiers, and additives on enantioseparation are discussed in terms of speed and resolution in SFC. Fundamental considerations and thermodynamic aspects are also presented. 

H. Kaga, Precision synthesis of (1 —> 6)-o -D-glucopyranan by cationic ring-opening polymerization of l,6-anhydro-tri-0-allyl-/8-D-glucopyranose, Macromol. Symposia, 181 (2002) 101-106 (b) A. Kusuno, M. Mori, T. Satoh, M. Miura, H. Kaga, and T. Kakuchi, Enantioseparation properties of (1 - 6)- -i)-glucopyranan and (1 - 6)-a-D-mannopyranan tris(phenylcarbamate)s as chiral stationary phases in HPLC, Chirality, 14 (2002) 498-502. 

Karlsson and Hermansson [30] used chemometrics for optimization of chiral separation of omeprazole and one of its metabolites on immobilized al-acid glycoprotein. Plasma was centrifuged at 2500 rpm and a portion (20-50 ji ) was injected into a 5-/rm Chiral-AGP column (10 cm x 4 mm) with al-acid glycoprotein immobilized to silica as a chiral stationary phase and acetonitrile-phosphate buffer of pH 5.7-7.2 as mobile phase (1 ml/min). Detection of omeprazole and its main metabolite, hydroxy-lated omeprazole, was performed at 302 nm. A statistical model was developed for the optimization of the operational parameters. The experimental data were evaluated with multivariate analyses column temperature and acetonitrile concentration were the most important variables for the enantioseparations. Complete enantiomeric separation for omeprazole and hydoxylated omeprazole was obtained within 15 min. 

Cass et al. [66] used a polysaccharide-based column on multimodal elution for the separation of the enantiomers of omeprazole in human plasma. Amylose tris (3,5-dimethylphenylcarbamate) coated onto APS-Hypersil (5 /im particle size and 120 A pore size) was used under normal, reversed-phase, and polar-organic conditions for the enantioseparation of six racemates of different classes. The chiral stationary phase was not altered when going from one mobile phase to another. All compounds were enantioresolved within the elution modes with excellent selectivity factor. The separation of the enantiomers of omeprazole in human plasma in the polar-organic mode of elution is described. 

Aboul-Enein, H. and Ali, I. (2002) Optimization Strategies for HPLC Enantioseparation of Racemic Drugs Using Polysaccharides and Macrocyclic Glycopeptide Antibiotic Chiral Stationary Phases, Farmaco 57, 513-529. 

Girod, M., Chankvetadze, B., and Blaschke, G. (2000) Enantioseparations in non-aqueous capillary electrochromatography using polysaccharide type chiral stationary phases, J. Chromatogr. A 887, 439-455. 

Yashima, E., Matsushima, T., Nimura, T., and Okamoto, Y. (1996) Enantioseparation on optically active stereoregular polyphenylacetylene derivatives as chiral stationary phase for HPLC, Korea Polym. J. 4, 139-146. 

Haginaka, J. (2001) Protein-based chiral stationary phases for high-performance liquid chromatography enantioseparations, J. Chromatogr. A 906, 253-273. 

Yamamoto, C., Hayashi, T., Okamoto, Y., and Kobayashi, S. (2000) Enantioseparation by using chitin phenylcarbamates as chiral stationary phases for high-performance liquid chromatography, Chem. Lett., 12-13. 

A more detailed discussion of the stationary phase types and mechanism of interaction and separation theory in relation to chiral compounds is given in Chapter 22. A large number of chiral stationary phases are currently available to meet the needs of the pharmaceutical industry for determination of the enantiomeric purity of active pharmaceutical ingredients, raw materials, and metabolites. As a consequence, there are a multitude of options in terms of columns, separation mode, and separation conditions to explore in achieving an enantioseparation. 

F. Wang,T. 0 Brien,T. Dowling, G. Bicker, and J. Wyvratt, Unusual effect of column temperature on chromatographic enantioseparation of dihydropyrimidone acid and methyl ester in amylose chiral stationary phase, J. Chromatogr. A 958 (2002), 69-77. 

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