Cyclodextrin retention properties

The pH, temperature, and ionic strength of the mobile phase also affect the cyclodextrin-solute complexation and retention properties. Many enantioseparations using cyclodextrin-modified systems involve solutes with an aromatic ring substituent or similar cyclic structure at the chiral center. A variety of chiral barbiturates, hydantoins, and related compounds have been resolved by using (3-cyclodextrin and alkylated B-cyclodextrin-modified systems. 

Conaway et al. (1995) extended the above-mentioned study of Perez et al. (1994) to determine by densitometric-HPTLC sugars in Helisoma trivolvis snails infected with the larval trematode Echinostoma trivolvis. Zarzycki et al. (1995) examined the retention properties of alpha-, beta-, and gamma-cyclodextrins using water-wettable RP-C-18 layers and mobile phases composed of acetonitrile, methanol, ethanol, or propanol with water or methanol in acetonitrile. Esaiassen et al. (1995) analyzed n-acetylchitooligosaccharides by use of the latroscan TLC/ flame ionization detection (FID) system. Brandolini et al. (1995) used automated multiple development (AMD)-HPTLC to monitor various carbohydrates—i.e., maltotetraose, maltotriose, maltose, glucose, and fructose—in different beers. 

Zarzyeki, P. K., Nowakowska, J., Chmielewska, A., and Lamparezyk, H. (1995). Retention properties of cyclodextrins in reversed-phase HPTLC. J. Planar Chromatogr.— Mod. TLC 8 227-231. 

The properties of cyclodextrins were studied using a packed column, whereas the effect of the liquid crystals were enhanced by employing a capillary column The stereoselective properties of these materials as stationary phases were studied with a set of alkylbenzoderivatives The mechanism of the separation is discussed on the basis of the retention data obtained The advantages and drawbacks of these phases are compared with conventional GC stationary phases and analytical applications are discussed ... 

The presence of water vapour in an inert carrier gas always affects the sorbate-cyclo-dextrin interaction. In contrast to analogous studies with sorbents such as alumina, silica gel and porous polymers, when the water vapour content in the carrier gas is 10% or more, a carrier gas (N2) was used containing 1-5% water vapour. The general effect is a shortening of the retention times which occurs with CDs at water vapour contents as low as 0.5% and increases with increasing water vapour content. This effect is especially pronounced for sorbates whose structures correspond to the dimensions of the a-CD cavity. Analogous conclusions cannot be drawn for /8-CD. A clarification of the contribution from the water vapour interaction with the cyclodextrin surface and the effect on its adsorption properties with respect to various types of sorbate is being studied further. 

Berto et al. [28] reported complexation properties of aqueous insoluble ionic P-cyclodextrin polymer cross-linked with pyromellitate anhydride biacid (PYR) towards such metal ions as Aiail). Mn(II). Cogi), Cuai), Znai). Cdai), Pt(IV), Tl and U(IV) at the different pH values. For most of investigated metal ions (except for tallium and platinum ions) the retention values were higher than 70%. In the case of Tl and Pt(IV), the retention was lower and equal to about 60% and 40%, respectively. For pH solution equal to 4, the retention values were changed as follow ... 

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