Cyclodextrins addition

Rawjee, Y.Y., Stark, D.U., Vigh, G. Capillary electrophoretic chiral separations with cyclodextrin additives I. acids Chiral selectivity as a function of pH and the concentration of P-cyclodextrin for fenoprofen and ibuprofen. J. Chromatogr. 1993, 635, 291-306. 

Y-H Lee, T-I Lin. Capillary electrophoretic determination of amino acids. Improvement by cyclodextrin additives. J Chromatogr A 716 335-346, 1995. 

YY Rawjee, RL Williams, G Vigh. Capillary electrophoretic chiral separations using cyclodextrin additives. 3. Peak resolution surfaces for ibuprofen and homatropine as a function of the pH and the concentration of /3-cyclodextrin. J Chromatogr A 680 599-607, 1994. 

Raben, A., Andersen, K.,Karberg,M. A., Holst, J. J., Astrup, A. (1997). Acetylation of or (J-cyclodextrin addition to potato starch beneficial effect on glucose metabolism and appetite sensations. Am. J. Clinic. Nutr., 66, 304-314. 

Sybilska D, Zukowski J, Cyclodextrin additives, in Chiral Separations by HPLC Applications to Pharmaceutical Compounds, Krstulovic AM (Ed.), Ellis Horwood,... 

Owens PK, Fell AF, Coleman M, Berridge JC. Method development in liquid chromatography with a charged cyclodextrin additive for chiral resolution of rac-amlodipine utilizing a central composite design. Chirality 1996 8(7) 466-476. 

The first objective was to develop a CZE separation (or fingerprint) using only migration times and peak areas for opium from different locations and poppy straw samples from different plants. Previously, a CZE method had shown poor separation for certain alkaloids in opium samples (24), and in other methods pH has had to be strictly controlled (25, 26). Some methods were unable to operate at the optimum detection wavelengths (25, 27, 28), while others have used various cyclodextrin additives to obtain separation (25, 29-31). 

Fig. 7 The effect of the addition of a sulfated a-cyclodextrin additive on the separation profile of eight analytes. The separation was carried out in the presence of a fixed concentration (5 mM) of sulfated a-cyclodextrin in 80 mM phosphate buffer, pH 1.9, and 1 1 (vol/vol) acetonitrile/water. (For details of experimental conditions, see Ref. 169.)...

In conventional reversed phase HPLC, differences in the physicochemical interactions of the eluate with the mobile phase and the stationary phase determine their partition coefficients and, hence, their capacity factor, k. In reversed-phase systems containing cyclodextrins in the mobile phase, eluates may form complexes based not only on hydrophobicity but on size as well, making these systems more complex. If 1 1 stoichiometry is involved, the primary association equilibrium, generally recognized to be of considerable importance in micellar chromatography, can be applied (11-13). The formation constant, Kf, of the inclusion complex is defined as the ratio of the entrance and exit rate constants between the solute and the cyclodextrin. Addition of organic modifiers, such as methanol, into the cyclodextrin aqueous mobile phase should alter the kinetic and thermodynamic characteristics of the system. This would alter the Kf values by modifying the entrance and exit rate constants which determine the quality of the separation. 

The Effect of pH on the Separation of Duloxetine Enantiomers Using Hydroxypropyl-P-Cyclodextrin Additives... 

The most common chiral additives used in chiral capillary electrophoresis with micellular solutions (mostly micelles of sodium dodecylsulphate) are derivatives of the three basic cyclodextrins. This system might be considered more of a chromatographic process than one that is electrophoretic, as the solutes are distributed between the aqueous electrolyte phase and the cyclodextrin/micelle phase. The derivatized cyclodextrin additive will also be distributed between the electrolyte and the micelles, the extent of which will depend on the type of derivatized cyclodextrin and its capacity for dispersive or polar interactions with the micelles. As the cyclodextrin additive itself partitions between the electrolyte and the micelle (albeit the distribution under certain circumstances may be small) some of the chiral additive will be distributed on the micelle surface and will act as a chiral stationary phase. 

It is also seen that the solute velocity (V), and thus its retention time, will not only depend on the distribution coefficient of the enantiomer, but also depend on the relative electrosmotic velocities of the electrolyte and the micelles, together with the relative volumes of the electrolyte and micelles in the system. There is a further complication, the cyclodextrin additive must also behave as a solute and, although it is often assumed that it resides solely in the electrolyte and is not distributed in the micelles, this will depend on the character of the derivatized cyclodextrin and whether or not it can interact with the micelle. This will obviously differ from one derivative to another. 

Li JG, Zhao FJ, Ju HX (2006) Simultaneous electrochemiluminescence determination of sulpiride and tiapride by capillary electrophoresis with cyclodextrin additives. J Chromatogr B 835(l-2) 84-89. doi 10.1016/j.jchromb.2006.03.017... 

C 8 column (A = 254nm) using either an 80/20 or a 75/25 methanol/water mobile phase with 0-2.5 mM y- or j8-cyclodextrin added. The v-cyclodextrin additive generated better resolution and shorter elution times. 

The rate and extent of biotransformation of high concentrations of benzaldehyde to phenylacetyl carbinol by inunobilized cells of S. cerevisiae were stimulated by additions of (3-cyclodextrins to fermentation medium [56]. With cyclodextrin additions of 0.5-1.5% and cumulative doses of benzaldehyde of 12 and 14 g/L, the yield of phenylacetyl carbinol obtained was about twofold higher than in the control experiment. Besides, these additions caused faster glucose consumption and benzaldehyde utilization. 

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