Stationary phases cyclodextrin

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. 

Table 2. Retention Data for Racemic Compounds Separated on a p-Cyclodextrin Stationary Phase ...

T. J. Ward, D. W. Armstrong, Cyclodextrin-stationary phases in Chromatographic chiral separations, M. Zief, L. J. Crane (Eds.), Chromatographic Science Series, Vol. 40, Marcel Dekker, New York (1988) Chapter 5. 

Elargitai, T., Kaida, Y., and Okamoto, Y., Preparation and chromatographic evaluation of 3,5-dimethylphenyl carbamoylated beta-cyclodextrin stationary phases for normal-phase high-performance liquid-chromatographic separation of enantiomers, J. Chromatogr., 628, 11, 1993. 

Chen, S. et al., Enantioresolntion of substituted 2-methoxy-6-oxo-l,4,5,6-tetrahydropyridine-3-carbanitriles on macrocyclic antibiotic and cyclodextrin stationary phases, 7. Liq. Chromatogr., 18, 1495, 1995. 

Yoshida, K. Nakagama, T. Uchiyama, K. and Hobo, T. (1998) Photo responsive chromatographic behavior of dansyl amino acid enantiomers using azobenzene-modified cyclodextrin stationary phases in... 

Juza, M, Braun, M., and Schurig, V. (1997) Preparative enantiomer separation of the chiral inhalation anesthetics enfiurane, isoflurane and desflurane by gas chromatography on a derivatized 7-cyclodextrin stationary phase, J. Chromatogr. A 769, 119-127. 

Schiirch, S., Saxer, A., Claude, S., Tabacchi, R., Trusch, B., and Hulliger, J. (2001) Semi-preparative gas chromatographic separation of ah-trans-perhydrotriphenylene enantiomers on a chiral cyclodextrin stationary phase, J. Chromatogr. A 905, 175-182. 

Jung and Schurig [7] have investigated enantiomeric separations using capillary SFC and an immobilized cyclodextrin stationary phase of film thickness 0.25 /tm. The authors found no loss in selectivity and column performance after several months. Many NSAID enantiomers could be separated, but amine-containing drugs such as ephedrine or synephrine had to be derivatized with trifluoroacetic acid anhydride prior to assay (see Fig. 

S. N. El-Gizawy, A. N. Ahmed, and N. E. El-Rabbat, High performance liquid chromatographic determination of multivitamin preparations using a chemically bonded cyclodextrin stationary phase, Anal. Lett., 24 1173 (1991). 

Enantiomeric analysis of a new antiinflammatory agent in rat plasma using a chiral p-cyclodextrin stationary phase" (71). The R,R S,S enantiomers of the investigational antiinflammatory agent trans-6,6a,7,10, 10a,ll-hexahydro-8,9-dimethyl-U-oxodibenz[b,e]-oxepin-3-acetic add (HOA) were resolved on the p-CD CSP after extraction from rat plasma. The mobUe phase was a mixture of 0.05 M potassium dihydrogenphosphate (pH 5.3) and methanol (35 65, v/v) the flow rate was 1.0 mL/min and the temperature was 22 1 C. The results of the study indicated that the inactive (—) enantiomer was cleared from the plasma more rapidly than the active (+) isomer. 

These stationary phases separate enantiomers on the basis that one isomer fits in the pocket and the other does not. In this fashion, the relative speed of the isomers is different, and separation results. There are three main types of inclusion chiral stationary phases a-cyclodextrin, /Tcyclodextrin, and y-cyclodextrin. From these three native cyclodextrins, several derivations can be made to alter the selectivity of the inclusion complex, including formation of acetates, esters, and carbamates. Astec produces all three native cyclodextrin stationary phases as well as several derivatized phases (called the Cyclobond series), and as with their macrolide polypeptide phases, they are covalently bonded. 

Ahmed, A.N. El-Gizawy, S.M. Use of chemically-bonded cyclodextrin stationary phase for high performance liquid chromatographic determination of Feldene capsules. J.Chromatogr.Sci., 1987, 25, 424-426 [column temp 35]... 

A Selection Guide to DEXTM Columns Stable derivatized cyclodextrin stationary phases for high resolution analyses of optical and positional isomers. In Chiral Cyclodextrin Capillary GC Columns. Sigma-Aldrich Co. Available at http // vww.sigmaaldrich.eom/etc/medialib/docs/Supelco/Bulletin/6504.Par.0001.File.tmp/ 6504.pdf. 

Chromatogram of a Test Mixture for a Permethylated a-Cyclodextrin Stationary Phase Courtesy of Supelco... 

Cyclodextrin stationary phases are applicable to as wide variety of compounds, often without derivatization. Chiral separations by GC are becoming more and more important, and for very difficult separations, it is easy to increase the length of the capillary column to produce the necessary number of theoretical plates. 

S. Chen, Y. Liu, D.W. Armstrong, P. Victory and B. Martinez-Teipel, Enantioresolution of Substitued 2-Methoxy-6-oxo-l,4,5,6-tetrahydro-pyridine-3-carbonitriles on Macrocyclic Antibiotic and Cyclodextrin Stationary Phases, J. Liq. Chromato., 18(8)(1995)474. 

G.W. Tindall, Bonded Cyclodextrin Stationary Phase Columns for the Separation of Cis/Trans Cyclohexane Derivatives,Chromatogr., 10(1987)1077. 

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