Effect of urea addition on chiral separation of dansylamino acids by capillary zone electrophoresis with cyclodextrins

Yoshinaga, Masanobu; Tanaka, Minoru

doi:10.1016/0021-9673(95)00501-3

Cited by 31 publications

(16 citation statements)

References 24 publications

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“…Dns-amino acids have already been used as model system for studying the enantioseparation ability of native b-CD [25][26][27] and its derivatives [12,[28][29][30][31] by CE. Compared with these reported chiral selectors, our single isomers, especially [bim-CD][Cl] can offer higher resolutions for Dns-amino acids not only in acidic BGEs but also in basic BGEs.…”

Section: Effect Of Ph On Enantiomer Separationmentioning

confidence: 99%

Synthesis and application of single-isomer 6-mono(alkylimidazolium)-β-cyclodextrins as chiral selectors in chiral capillary electrophoresis

et al. 2005

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Novel single isomers of positively charged beta-CDs were prepared via nucleophilic substitution of 6-monotosyl-beta-CD with alkylimidazoles to afford 6-mono(alkylimidazolium)-beta-CD tosylates and then 6-mono(alkylimidazolium)-beta-CD chlorides by anion exchange. The chiral resolution abilities of these cationic CDs were studied by CE using dansyl (Dns)-amino acids as model analytes. From the experimental results, it was found that both resolution and selectivity of these cationic CDs were dependent on the following parameters: concentration of chiral selectors, pH of the running buffer, counteranions of the CDs, side chain length of the n-alkyl-imidazolium cation, temperature of the capillary column, and organic modifier used. The concentration of chiral selectors required for enantioseparation varied from 3 to 30 mM. The BGE pH played an important role in the resolution of Dns-amino acids. For acidic BGEs, chiral resolution increased with pH (4.0-6.0) and reached a local maximum at pH 6.0. However, better resolutions were obtained with basic phosphate buffer at pH 9.6. Methanol was found to be an effective organic modifier for the resolution of Dns-amino acids by CE.

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Section: Effect Of Ph On Enantiomer Separationmentioning

confidence: 99%

Synthesis and application of single-isomer 6-mono(alkylimidazolium)-β-cyclodextrins as chiral selectors in chiral capillary electrophoresis

et al. 2005

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“…The solubility of the native cyclodextrins depends strongly on the number of glucopyranoses [42,43] and may be increased by addition of either alcohols [43] or another organic solvent miscible with water [44] or urea [45]. However, the competition of the additives with the analytes for the cyclodextrin affects the separation [46] since cyclodextrins have a general capability to host any compound.…”

Section: Cyclodextrinsmentioning

confidence: 99%

Chiral separations in capillary electrophoresis

Vespalec

Boček

1999

Electrophoresis

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“…Different effects of urea on b-CD-mediated enantioseparations have been described in the literature. For example, a significantly enhanced selectivity was observed in the case of enantioseparations of dansylated amino acids upon addition of 7 M urea [2]. In CD-modified MEKC the enantioseparation of miconazol improved in the presence of 1 M urea [7].…”

mentioning

confidence: 95%

Effect of urea on analyte complexation by 2,6‐dimethyl‐β‐CD in peptide enantioseparations by CE

Hammitzsch-Wiedemann

Scriba

2009

Electrophoresis

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The aim of the present study was the investigation of the effect of urea on analyte complexation in CD-mediated separations of peptide enantiomers by CE in the pH range of about 2-5. pH-independent complexation and mobility parameters in the absence and presence of 2 M urea were obtained by three-dimensional, non-linear curve fitting of the effective analyte mobility as a function of pH and heptakis-(2,6-di-O-methyl)-beta-CD concentration. Urea led to decreased binding strength of the CD towards the protonated and neutral analyte enantiomers as well as to decreased mobilities of the free analytes. In contrast, mobilities of the fully protonated enantiomer-CD complexes as well as the pK(a) values of the free and complexed analytes increased. The effect of urea on separation efficiency varied with pH and CD concentration. In the case of Ala-Tyr and Ala-Phe, separations improved in the presence of urea at pH 2.2. In contrast, separations were impaired by urea at pH 3.8 and low concentrations of the CD. Decreased separation efficiency was noted for Asp-PheOMe and Glu-PheNH(2) at low CD concentrations when urea was added but separations improved at higher CD concentrations over the entire pH range studied. The effect of urea on analyte complexation appeared to be primarily non-stereoselective. Furthermore, the pH-dependent reversal of the enantiomer migration order observed for Ala-Tyr and Ala-Phe can be rationalized by the complexation and mobility parameters.

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Effect of urea addition on chiral separation of dansylamino acids by capillary zone electrophoresis with cyclodextrins

Cited by 31 publications

References 24 publications

Synthesis and application of single-isomer 6-mono(alkylimidazolium)-β-cyclodextrins as chiral selectors in chiral capillary electrophoresis

Synthesis and application of single-isomer 6-mono(alkylimidazolium)-β-cyclodextrins as chiral selectors in chiral capillary electrophoresis

Chiral separations in capillary electrophoresis

Effect of urea on analyte complexation by 2,6‐dimethyl‐β‐CD in peptide enantioseparations by CE

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