Chiral stationary phases cyclodextrins

Pihlainen, K. and Kostiainen, R., Effect of the eluent on enantiomer separation of controlled drugs by liquid chromatography-ultraviolet absorbance detection-electrospray ionisation tandem mass spectrometry using vancomycin and native fi-cyclodextrin chiral stationary phases, J. Chromatogr. A, 1033, 91, 2004. 

AM Rizzi, S Cladrowa-Runge, H Jonsson, S Osla. Enantiomeric resolution of derivatized DL-amino acids by high-performance liquid chromatography using /3-cyclodextrin chiral stationary phase a comparison between derivatization labels. J Chromatogr A 710 287-295, 1995. 

H. Weems and K. Zamani, Resolution of terfenadine enantiomers by j3-cyclodextrin chiral stationary phase high-performance liquid chromatography, Chirality, 4 268 (1992). 

K.M. Fried, A.E. Young, S. Usdin Yasuda, l.W. Wainer, The enantioselective determination of chlorpheniramine and its major metabolites in human plasma using chiral LC on a P-cyclodextrin chiral stationary phase and MS detection, J. Pharm. Biomed. Anal., 27 (2002) 479. 

D. W. b-Cyclodextrin chiral stationary phases for liquid chromatography. Effect of the spacer arm on chiral recognition,... 

More recently MacDonnell, Armstrong and coworkers reported a highly efficient method for the resolution of [Ru(diimine)3] complexes using HPLC with cyclodextrin chiral stationary phase. This technique allowed the separation of several monomeric and also dinuclear ruthenium polypyridyl compounds. 

Stalcup, AM and KH Gahm (1996). A sulfated cyclodextrin chiral stationary phase for high-performance liquid chromatography. Analytiacl Chemistry, 68(8), 1369-1374. 

A. Berthod, H.L. Jin, T.E. Beesley, J.D. Duncan and D.W. Armstrong, Cyclodextrin Chiral Stationary Phases for Liquid Chromatographic Separations of Drug Stereoisomers, J. Pharm. Biomed Anal., 8(2)(1990)123. 

K.L. Williams, L.C. Sander and S.A. Wise, Comparison of Liquid and Supercritical Fluid Chromatography Using Naphthylethylcarbamoylated- 3-cyclodextrin Chiral Stationary Phases, J. Chromatogr. A, 746(1996)91. 

Chiral Stationary Phases for Gas Chromatography Small Molecule Stationary Phases Chiral Polysiloxane Stationary Phases Chiral Metal Chelating Stationary Phases Cyclodextrin Chiral Stationary Phases... 

The successful separation of enantiomeric pairs of zwitter-ionic mdo-carbaboranes containing the C2B9-core has been reported. This has been achieved by using )3-cyclodextrin chiral stationary phases.42... 

Chromatography Online, Chrial-GC - Cyclodextrin chiral stationary phases from chrial gas chromatography, http //www.chromatography-online.org/Chrial-GC/Contemporary-Chiral-Stationary-Phases/Cyclodextrin.php. 

Mitchell C, Desai M, McCulla R, Jenks W, Armstrong D. Use of native and derivatized cyclodextrin chiral stationary phases for the enantioseparation of aromatic and aliphatic sulfoxides by high performance liquid chromatography. Chromatographia 2002 56 127-35. 

Lipka, E., Glacon, V., Mackenzie, G., Ewing, D., Len, C., Postel, D., Vaccher, M. P., Bonte, J. P. and Vaccher, C. HPLC Separation and Determination of Enantiomeric Purity of Novel Nucleoside Analogs, on Cyclodextrin Chiral Stationary Phases, Using Reversed and Polar Organic Modes. Anal. Lett 37 385, 2004. 

Table 4 Substituent-free energy contributions in cal/mol for enantiomeric recognition on (5)-naphthylethyl carbamate-substituted fS-cyclodextrin chiral stationary phase...

Sun P, Krishnan A, Yadav A, Singh S, MacDonnell FM, Armstrong DW (2007) Enantiomeric separations of ruthenium (II) polypridyl complexes using high-performance liquid chromatography with cyclodextrin chiral stationary phases. Inoig Chem 46 10312-10320... 

Williams KL, Sander LC, Wise SA (1996) Comparison of liquid and supercritictil fluid chromatography using naphthylethylcarbamoylated-P-cyclodextrin chiral stationary phases. J Chromatogr A 746 91-101... 

Limitations with the chiral selectivity of the native cyclodextrins fostered the development of various functionalized cyclodextrin-based chiral stationary phases, including acetylated (82,83), sulfated (84), 2-hydroxypropyl (85), 3,5-dimethylphenylcarbamoylated (86) and... 

Gc chiral stationary phases can be broadly classified into three categories diamide, cyclodextrin, and metal complex. 

Gyclodextrins. As indicated previously, the native cyclodextrins, which are thermally stable, have been used extensively in Hquid chromatographic chiral separations, but their utihty in gc appHcations was hampered because their highly crystallinity and insolubiUty in most organic solvents made them difficult to formulate into a gc stationary phase. However, some functionali2ed cyclodextrins form viscous oils suitable for gc stationary-phase coatings and have been used either neat or diluted in a polysiloxane polymer as chiral stationary phases for gc (119). Some of the derivati2ed cyclodextrins which have been adapted to gc phases are 3-0-acetyl-2,6-di-0-pentyl, 3-0-butyryl-2,6-di-0-pentyl,... 

Although the chiral recognition mechanism of these cyclodexttin-based phases is not entirely understood, thermodynamic and column capacity studies indicate that the analytes may interact with the functionalized cyclodextrins by either associating with the outside or mouth of the cyclodextrin, or by forming a more traditional inclusion complex with the cyclodextrin (122). As in the case of the metal-complex chiral stationary phase, configuration assignment is generally not possible in the absence of pure chiral standards. 

Cyclodextrin stationary phases utilize cyclodextrins bound to a soHd support in such a way that the cyclodextrin is free to interact with solutes in solution. These bonded phases consist of cyclodextrin molecules linked to siUca gel by specific nonhydrolytic silane linkages (5,6). This stable cyclodextrin bonded phase is sold commercially under the trade name Cyclobond (Advanced Separation Technologies, Whippany, New Jersey). The vast majority of all reported hplc separations on CD-bonded phases utilize this media which was also the first chiral stationary phase (csp) developed for use in the reversed-phase mode. 

Recently, multidimensional GC has been employed in enantioselective analysis by placing a chiral stationary phase such as a cyclodextrin in the second column. Typically, switching valves are used to heart-cut the appropriate portion of the separation from a non-chiral column into a chiral column. Heil et al. used a dual column system consisting of a non-chiral pre-column (30 m X 0.25 mm X 0.38 p.m, PS-268) and a chiral (30 m X 0.32 mm X 0.64 p.m, heptakis(2,3-di-(9-methyl-6-(9-tert-butyldimethylsilyl)-(3-cyclodextrin) (TBDM-CD) analytical column to separate derivatized urinary organic acids that are indicative of metabolic diseases such as short bowel syndrome, phenylketonuria, tyrosinaemia, and others. They used a FID following the pre-column and an ion trap mass-selective detector following the... 

A. M. Stalcup, Cyclodextrin bonded chiral stationary phases in enantiomer separations in A practical approach to chiral separations by liquid chromatogra.phy, G. Subramanian, VCH, Weinheim (1994) Chapter 5. 

Many racemic mixtures can be separated by ordinary reverse phase columns by adding a suitable chiral reagent to the mobile phase. If the material is adsorbed strongly on the stationary phase then selectivity will reside in the stationary phase, if the reagent is predominantly in the mobile phase then the chiral selectivity will remain in the mobile phase. Examples of some suitable additives are camphor sulphonic acid (10) and quinine (11). Chiral selectivity can also be achieved by bonding chirally selective compounds to silica in much the same way as a reverse phase. A example of this type of chiral stationary phase is afforded by the cyclodextrins. 

There is a wide variety of commercially available chiral stationary phases and mobile phase additives.32 34 Preparative scale separations have been performed on the gram scale.32 Many stationary phases are based on chiral polymers such as cellulose or methacrylate, proteins such as human serum albumin or acid glycoprotein, Pirkle-type phases (often based on amino acids), or cyclodextrins. A typical application of a Pirkle phase column was the use of a N-(3,5-dinitrobenzyl)-a-amino phosphonate to synthesize several functionalized chiral stationary phases to separate enantiomers of... 

Because plasma and urine are both aqueous matrixes, reverse-phase or polar organic mode enantiomeric separations are usually preferred as these approaches usually requires less elaborate sample preparation. Protein-, cyclodextrin-, and macrocyclic glycopeptide-based chiral stationary phases are the most commonly employed CSPs in the reverse phase mode. Also reverse phase and polar organic mode are more compatible mobile phases for mass spectrometers using electrospray ionization. Normal phase enantiomeric separations require more sample preparation (usually with at least one evaporation-to-dryness step). Therefore, normal phase CSPs are only used when a satisfactory enantiomeric separation cannot be obtained in reverse phase or polar organic mode. 

As yet, the number of applications is limited but is likely to grow as instrumentation, mostly based on existing CE systems, and columns are improved and the theory of CEC develops. Current examples include mixtures of polyaromatic hydrocarbons, peptides, proteins, DNA fragments, pharmaceuticals and dyes. Chiral separations are possible using chiral stationary phases or by the addition of cyclodextrins to the buffer (p. 179). In theory, the very high efficiencies attainable in CEC mean high peak capacities and therefore the possibility of separating complex mixtures of hundreds of... 

Another chiral stationary phase is modified cyclodextrin. Cyclodextrins are cyclic chiral carbohydrates composed of six, seven, or eight glucopyranose... 

Acetylacetone, 7 148-149, 164 74 596-598 molecular formula, 5 712t TV-Acetylacrylamide, 7 293 Acetyl anchoring groups, 5 683t Acetylated cyclodextrin-based chiral stationary phase, 6 87 Acetylated lanolin, cosmetically useful lipid, 7 833t... 

Sulfated alkenes, 23 538 Sulfated carbohydrate products, 23 538 Sulfated cyclodextrin-based chiral stationary phase, 6 87 Sulfated fatty acids, 23 538 Sulfated fatty alcohol ethoxylates, 23 537 Sulfated fatty oils, 23 538 Sulfated products... 

The bonding of cyclodextrins to silica has provided a range of media known as chiral stationary phases (CSPs), which are capable of... 

Investigations on the stereochemistry of chiral semiochemicals may be carried out by (gas) chromatographic separation of stereoisomers using chiral stationary phases, e.g. modified cyclodextrins [32]. Alter natively, formation of diastereomers (e.g. Mosher s ester or derivatives involving lactic acid etc.) may be followed by separation on conventional achiral stationary phases. Assignment of the absolute configuration of the natural product will again need comparison with an authentic (synthetic) reference sample. 

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