Thermodynamic study and separation mechanism of diltiazem optical isomers in packed-column supercritical fluid chromatography

Yaku, Koji; Aoe, Keiichi; Nishimura, Noriyuki; Morishita, Fujio

doi:10.1016/s0021-9673(99)00308-8

Cited by 32 publications

(21 citation statements)

References 26 publications

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“…This is in good accordance with past studies showing nonlinear van't Hoff plots for retention factors but linear plots for separation factors. 30,33 On the basis of the regression lines, we were able to estimate DDH8, DDS8 and the isoelution temperature for all racemates. The results can be seen in Table 1, along with the values of correlation coefficient (R).…”

Section: Effect Of Temperature On Enantioseparationmentioning

confidence: 99%

Chiral separation of phospine‐containing α‐amino acid derivatives using two complementary cellulosic stationary phases in supercritical fluid chromatography

et al. 2009

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Enantiomeric separations of six amino-acid derivatives have been studied using packed-column supercritical fluid chromatography with two polysaccharide-based enantioselective stationary phases: cellulose tris(3,5-dimethylphenylcarbamate) and cellulose tris(3-chloro-4-methylphenylcarbamate) (Lux Cellulose-1 and -2). The effect of analyte structure on retention and separation was studied. Varied mobile phase compositions were investigated: alcohol modifier percentage was increased from 3 to 40% but smaller amounts were most effective in separating these compounds. Besides, ethanol was preferred to methanol or isopropanol as it proved to be a good compromise to achieve sufficient resolution in a reasonable analysis time. Moreover, a carbon dioxide-ethanol mixture allows performing analyses in safe and green conditions. The effect of temperature at constant mobile phase composition was explored between 10 and 40 degrees C. In most cases, increasing the temperature improved the chiral separation, up to an optimum temperature. The results are discussed in line with the structure variation of the racemic derivatives analyzed and the two columns are compared. The two columns were shown to provide complementary selectivities for the investigated solutes: whereas Lux 1 provided separation for five of the six racemates, Lux 2 could resolve the last racemic mixture. Finally, optimized conditions of separation are defined.

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Section: Effect Of Temperature On Enantioseparationmentioning

confidence: 99%

Chiral separation of phospine‐containing α‐amino acid derivatives using two complementary cellulosic stationary phases in supercritical fluid chromatography

et al. 2009

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“…These results suggested that different chiral recognition mechanisms were involved in LC and SFC modes. The reason might be that the chiral active sites of the phenyl group of analytes and the phenylcarbamate group of the CSP have different solvation states in SFC and NPLC conditions [182]. The same conclusion was drawn from a systematic comparison of LC and SFC based on the enantioseparations of various pharmaceutical compounds on cellulose-and amylose-derived CSPs, i.e., Chiralcel OD and Chiralpak AD, respectively [171].…”

Section: Sfc and Polysaccharide Cspsmentioning

confidence: 79%

“…It can be expected that SFC and LC may render unique enantioselectivity depending on the CSP and the analyte. Noticeable discrepancies between NPLC and SFC for polysaccharide CSPs have been well recognized in many studies [167,171,[180][181][182].…”

Section: Sfc and Polysaccharide Cspsmentioning

confidence: 99%

Chiral Recognition Mechanism: Practical Considerations for Pharmaceutical Analysis of Chiral Compounds

2010

Chiral Recognition in Separation Methods

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“…On the other hand, the high T iso of compound 2 indicated an enthalpy-controlled separation, suggesting that better separation would occur at lower temperatures. 32 …”

Section: Effect Of Temperaturementioning

confidence: 99%

Chiral separation of neonicotinoid insecticides by polysaccharide‐type stationary phases using high‐performance liquid chromatography and supercritical fluid chromatography

et al. 2010

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The enantiomeric separations of three neonicotinoid insecticides (identified as compounds 1, 2, and 3) were performed on three polysaccharide-type chiral columns, that is, Chiralcel OD-H, Chiralpak AD-H, and Chiralpak IB, by high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). Effects of the modifier percentage and column temperature on chiral recognitions of chiral stationary phases were also studied. Both 1 and 2 could be resolved on all three columns selected, with the highest R(s) values obtained on Chiralpak AD-H and Chiralcel OD-H, respectively. However, satisfactory separation of the four stereoisomers of 3 was only achieved on Chiralcel OD-H. Considering the effects of ethanol on the values of k, α, and R(s), we concluded that hydrogen bonding, π-π, and/or dipole-dipole interactions might be all responsible for the chiral separation. In comparison to HPLC, a shorter run time was achieved for 1 and 2 by SFC. However, 3 could not be stereoselectively resolved using SFC. On the basis of the calculated thermodynamic parameters, we found that the separation processes of enantiomers of 1 and 2 were entropy controlled and enthalpy controlled, respectively.

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Thermodynamic study and separation mechanism of diltiazem optical isomers in packed-column supercritical fluid chromatography

Cited by 32 publications

References 26 publications

Chiral separation of phospine‐containing α‐amino acid derivatives using two complementary cellulosic stationary phases in supercritical fluid chromatography

Chiral separation of phospine‐containing α‐amino acid derivatives using two complementary cellulosic stationary phases in supercritical fluid chromatography

Chiral Recognition Mechanism: Practical Considerations for Pharmaceutical Analysis of Chiral Compounds

Chiral separation of neonicotinoid insecticides by polysaccharide‐type stationary phases using high‐performance liquid chromatography and supercritical fluid chromatography

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