Carbon dioxide supercritical fluid chromatography on a chiral diamide stationary phase for the resolution of D- and L-amino acid derivatives

Hara, Shoji; Dobashi, Akira; Kinoshita, Kyo.; Hondo, Toshinobu; Saito, Muneo; Senda, Masaaki

doi:10.1016/s0021-9673(01)94702-8

Cited by 49 publications

(6 citation statements)

References 12 publications

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“…3) And sub-and supercritical fluid chromatography (subFC and SFC) 4,5) has been demonstrated to be a good method for direct chiral separation. Carbon dioxide (CO 2 ) is widely used as an eluent for supercritical fluid because of its low cost, low toxicity, and easy handling.…”

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confidence: 99%

Sub- and Supercritical Chiral Separation of Racemic Compounds on Columns with Stationary Phases Having Different Functional Groups

Kasai

Tsubuki

Matsuo

et al. 2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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Separation of the enantiomers of each of three different racemates, neutral rac-a a-tetralol, acidic rac-2-phenylpropionic acid, and basic rac-1-phenylethylamine, using subcritical and supercritical fluid chromatography with two different chiral stationary phases, heptakis(2,3,6-tri-O-methyl)-b b-cyclodextrin (Sumichiral OA-7500 column) and tris(3,5-dimethylphenylcarbamate) of amylose (Chiralpak AD-H column), was compared. The elution order of the enantiomers of the three racemates was determined, and the effects of the type of alcohol modifier, column oven temperature, mobile phase composition, flow rate, and pressure were examined. The most appropriate column oven temperature depended on both the type of alcohol modifier and the compound analyzed. Lower alcohol content improved the peak separation of both rac-a a-tetralol on the Sumichiral OA-7500 column and rac-1-phenylethylamine on the Chiralpak AD-H column, while the same phenomenon was not observed with either rac-a a-tetralol or rac-2-phenylpropionic acid on the Chiralpak AD-H column. Decreasing outlet pressure improved the peak separation obtained with rac-2-phenylpropionic acid, but had little effect on either rac-a atetralol or rac-1-phenylethylamine.

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Sub- and Supercritical Chiral Separation of Racemic Compounds on Columns with Stationary Phases Having Different Functional Groups

Kasai

Tsubuki

Matsuo

et al. 2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…Such an increase in column efficiency can often be obtained by operating under sub- or supercritical fluid conditions rather than under HPLC conditions. Numerous workers − have demonstrated the benefits this efficiency brings to chiral analysis. This increased efficiency does not generally come at the expense of selectivity.…”

mentioning

confidence: 99%

“Entropically Driven” Chiral Separations in Supercritical Fluid Chromatography. Confirmation of Isoelution Temperature and Reversal of Elution Order

Stringham

Blackwell

1996

Anal. Chem.

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Chiral separations depend upon column efficiency and chiral selectivity. Supercritical fluid chromatography (SFC) has been shown to have pronounced advantages in chiral separations due to its enhanced column efficiency at normal flow rates. Examination of factors affecting selectivity in SFC is crucial to systematic chiral method development. Selectivity is a compromise between differences in enantiomeric binding enthalpy and disruptive entropic effects. Increased temperature will decrease the effect of differences in enantiomer binding enthalpy, eventually decreasing selectivity to a point where the enantiomers coelute. Extension of this thermodynamic theory predicts that further increases in temperature lead to selectivity values of less than 1.0, and elution order of the enantiomers reverses. In this region separations are said to be "entropically driven", and selectivity increases (decreases from 1.0) with temperature. Performing separations in this region is attractive because column efficiency is also expected to increase with temperature. Such entropically driven separations have been observed only in gas chromatography. Most data used to support the application of this theory in SFC have been generated at subcritical temperatures, while theory purports to predict behavior above the critical temperature (T(c)). This approach ignores the effects of traversing the critical temperature in SFC, which is known to have a variety of unpredictable consequences. Work presented here shows the effect of temperatures above T(c) on chromatographic behavior. Contrary to theory, capacity factors increase near T(c) and column efficiency declines. Use of pressures well above the critical pressure lessens these effects. In accordance with theory, selectivity does decrease with temperature through T(c) and isoelution temperatures and two instances of elution order reversal are observed here for the first time in SFC.

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“…Column efficiency can be increased dramatically by operating under subcritical or supercritical fluid conditions rather than under HPLC conditions. Numerous workers − have demonstrated the benefits this efficiency enhancement brings to chiral analysis. Attempts at increasing selectivity are less clear.…”

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Effect of Various Modifiers on Selectivity in Packed-Column Subcritical and Supercritical Fluid Chromatography

et al. 1996

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A number of common mobile phase modifiers were characterized by chromatographing monofunctional probe solutes on a cyano-bonded stationary phase under subcritical and supercritical conditions. Solvatochromic analysis techniques were used to characterize the relative selectivity, efficiency, and eluotropic strengths of the various modified mobile phases. Analysis of the combined results suggests that modifier choice may be made in a rational manner to either enhance or mask a particular type of molecular interaction. This control is necessary for challenging applications such as chiral separations. The relative effects of each modifier property change depending on whether the chromatographic system is subcritical or supercritical, thus making knowledge of the phase equilibria associated with the mobile phase essential.

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Carbon dioxide supercritical fluid chromatography on a chiral diamide stationary phase for the resolution of D- and L-amino acid derivatives

Cited by 49 publications

References 12 publications

Sub- and Supercritical Chiral Separation of Racemic Compounds on Columns with Stationary Phases Having Different Functional Groups

Sub- and Supercritical Chiral Separation of Racemic Compounds on Columns with Stationary Phases Having Different Functional Groups

“Entropically Driven” Chiral Separations in Supercritical Fluid Chromatography. Confirmation of Isoelution Temperature and Reversal of Elution Order

Effect of Various Modifiers on Selectivity in Packed-Column Subcritical and Supercritical Fluid Chromatography

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