Chromatography cyclodextrin phases

Rizzi, A. M. and Plank, C., Coupled column chromatography in chiral separations systems employing P-cyclodextrin phases for chiral separation, /. Chromatogr., 557, 199, 1991. 

Capillary gas chromatography on optically active modified cyclodextrin phases is a simple, fast, accurate and highly sensitive method for the enantiomeric analysis of chiral volatile compounds. 

The precision of enantiomeric purity determinations by gas chromatography is high123 124-1 >s. This statement holds not only for small enantiomeric purities ( 0% ee), e.g., in the differentiation of a true racemate from enantiomerically slightly enriched mixtures (in reactions devoted to the amplification of optical activity under prebiotic conditions), but also for very high enantiomeric purities (— 100% ee), with detection of 1.0 to 0.1% (and less) of enantiomeric impurities (see Section 3.1.5.8). It is always advantageous if the enantiomer present as an impurity is eluted as the first peak from the gas chromatographic column (Section 3.1.5.3.). This is achieved by the proper selection of the chirality of the nonracemic stationary phase147-188 which, unfortunately, is not possible for the cyclodextrin phases. 

The extracts contained almost pure pheromone, with only minor amounts of other components. By comparison with synthetic samples, derivatization, and gas chromatography on a chiral cyclodextrin phase, the pheromone was identified as a 95 5 mixture of (5)- and (/ )-enantiomers of dimethyl citrate (cupilure (3), Fig. 4.2). Only the (5)-enantiomer was active (Tichy et al., 2001). Cupilure is probably present in ionized form on the silk (pK 3.5), because solvent extracts were neutral. The ionized carboxyl group may be conjugated to basic amino acids of the silk proteins. This would also explain why the pheromone is not volatile, despite its relatively low molecular weight, and is easily washed from the silk by water, including rain. In the tropical habitat of C. salei this would ensure the presence of cupilure only on freshly laid silk. 

The extent of stereoselectivity in the chiral synthesis can be checked by determining the enantiomeric excess of the optically active olefins in the products. The optical purity was determined by gas chromatographic resolution of enantiomers by means of an optically active column. Thermostable substituted cyclodextrins are well suited as asymmetric phases (206). The trimer, 2,4-dimethyl-l-heptene, was resolved into its enantiomers by capillary gas chromatography with an octakis(6-0-methyl-2,3-r/-0-pentyl-)-7-cyclodextrine phase. 

Gas Chromatography Stationary phase Amino Acid Derivatives Metal Chelates Cyclodextrin Derivatives... 

Liquid Chromatography Stationary phase Amino Acid Derivatives Low-Mass Synthetic Selectors Poly(saccharide) Derivatives Cyclodextrin Derivatives Glycopeptides Metal Chelates Proteins Helical Polymers... 

Some cyclodextrin derivatives used as chiral selectors in gas chromatography (Stationary phases commercially available on open tubular columns)... 

J. T. Anderson and G. Kaiser, Elution Order in Liquid Chromatography on Cyclodextrin Phases. Dependence on the Amount of Organic Modifier in the Eluent, Fresenius Z. Anal. Chem., 749(1989). 

Zukowski J., Pawlowska M., Nagatkina M. Armstrong D. W., High-performance Liquid Chromatographic Enantioseparation of Glycyl dipeptides and tripeptides on Native Cyclodextrin Phases, Mechanistic Considerations, Journal of Chromatography. 629 (1993), 169-179. 

There are three main types of chiral GC stationary phases (1) chiral amino acid derivatives [8-10] (2) chiral metal coordination compounds [11] and (3) cyclodextrin derivatives [12-14]. The cyclodextrin phases have proven to be the most versatile for gas chromatography. 

Source From Synthesis and properties of new cyclodextrin phenyl carbamates as capillary gas chromatography stationary phases, in Anal. Chim. Acta. ... 

Chiral compounds are frequently foimd among the flavor volatiles of fruits and, like many naturally occurring chiral compounds, one enantiomer usually exists with a greater preponderance when compared with its antipode. Chiral odor compounds may show qualitative and quantitative differences in their odor properties (7). For example, (/ )-(+)-limonene has an orange-like aroma while (5)-(-)-limonene is turpentine-like (5)-(+)-carvone is characteristic of caraway while its enantiomer has a spearmint odor (2). However, other chiral compounds, such as y 6-lactones, show very little enantioselectivity of odor perception (7). The occurrence of chiral flavor compounds in enantiomeric excess provides the analyst with a means of authenticating natural flavorings, essential oils, and other plant extracts. The advent of cyclodextrin-based gas chromatography stationary phases has resulted in considerable activity in the analysis of chiral compounds in flavor extracts of fruits, spices and other plants (i-7). 

Determined by gas chromatography on P-cyclodextrin phases after either reaction with (R)-a-methoxy-a-trifluoromethylphenylacetoyl chloride [(/ )-(+)-MTPA chloride] to provide the diastereomeric (/ )-(+)-MTPA esters, or after acetylation with acetic anhydride. 

The e.e. values of diastereomeric (/ )- or (5)-MTPA esters were determined by gas chromatography on (5-cyclodextrin phases [25]. 

Determined by gas chromatography on 3-cyclodextrin phases after acetylation. 

Analytically, the inclusion phenomenon has been used in chromatography both for the separation of ions and molecules, in Hquid and gas phase (1,79,170,171). Peralkylated cyclodextrins enjoy high popularity as the active component of hplc and gc stationary phases efficient in the optical separation of chiral compounds (57,172). Chromatographic isotope separations have also been shown to occur with the help of Werner clathrates and crown complexes (79,173). 

Immobilization. The abiUty of cyclodextrins to form inclusion complexes selectively with a wide variety of guest molecules or ions is well known (1,2) (see INCLUSION COMPOUNDS). Cyclodextrins immobilized on appropriate supports are used in high performance Hquid chromatography (hplc) to separate optical isomers. Immobilization of cyclodextrin on a soHd support offers several advantages over use as a mobile-phase modifier. For example, as a mobile-phase additive, P-cyclodextrin has a relatively low solubiUty. The cost of y- or a-cyclodextrin is high. Furthermore, when employed in thin-layer chromatography (tic) and hplc, cyclodextrin mobile phases usually produce relatively poor efficiencies. 

In relation to separation of nucleotides, Hoffman61 found that adenine nucleotides interacted most strongly with cycloheptaamylose, presumably by inclusion of the base within the cavity of cyclodextrin. When epichlorohydrin-cross-linked cycloheptaamylose gel was used as a stationary phase for nucleic acid chromatography, adenine-containing compounds were retarded most strongly. 

Early attempts to use cyclodextrins and their simple derivatives as chira stationary phases in gas chromatography met... 

Terabe, S., Ozaki, H., Otsuka, K., and Ando, T., Electrokinetic chromatography with 2-O-carboxymethyl-P-cyclodextrin as a moving "stationary" phase, /. Ckromatogr., 332, 211, 1985. 

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

The mobile phases used with cyclodextrin CSPs are similar to those used in reverse phase chromatography, ie water or buffer solutions modified with methanol or acetonitrile. 

Lopez-Nicolas JM, Nunez-Delicado E, Perez-Lopez AJ, Carbonell A and Cuadra-Crespo P. 2006. Determination of stoichiometric coefficients and apparent formation constants for (3-cyclodextrin complexes of trans-resveratrol using reversed-phase liquid chromatography. J Chromatogr A 1135 158—165. 

FEURLE, J., JOMAA, H., WILHELM, M GUTSCHE, W.B., HERDRICH, M., Analysis of phosphorylated carbohydrates by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry utilising p-cyclodextrin bonded stationary phase, J. Chromatogr., 1998,803,111-119. 

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