Temperature effects enantioseparation

Rojkovieova, T. et al.. Study of the mechanism of enantioseparation. Vll. Effect of temperature on retention of some enantiomers of phenylcarbamic acid derivates on a teicoplanin aglycone chiral stationary phase, J. Liq. Chrom. Rel. TechnoL, 27, 1653, 2004. 

F. Wang,T. 0 Brien,T. Dowling, G. Bicker, and J. Wyvratt, Unusual effect of column temperature on chromatographic enantioseparation of dihydropyrimidone acid and methyl ester in amylose chiral stationary phase, J. Chromatogr. A 958 (2002), 69-77. 

Wang, F. O Brien, T. Dowhng, T. Bicker, G. Wyvratt, J. 36. Unusual effect of column temperature on chromatographic enantioseparation of dihydropyrinudinone acid and methyl... 

A chiral CE separation method was developed for ephe-drine, norephedrine, synephrine, and epinephrine using a 20-mM phosphate buffer with pH 3.0 containing 0.4% w/v S-P-CD as CS. Peng et al. performed the separation in 50-pm i.d. capillaries with total and effective lengths of 60 and 50 cm, respectively. The effect of the temperature (20-60°C) on the CD enantioselectivity was investigated. An increase in temperature decreased the enantioselectivity toward ephedrine and norephedrine but increased that toward synephedrine and epinephrine. This observation suggests that the enantioseparation of ephedrine and norephedrine was an enthalpy-driven process, while for synephrine and epinephrine, it was entropy-driven. 

In Chapter 11, the authors introduce both the direct approaches to enantioseparation of selected adrenergic drugs (carried out using MIPs, impregnated CSPs, or chiral mobile phase modifiers) and the indirect ones. They also discuss selected physicochemical aspects of the approaches discussed (e.g., effects of the concentration of the stationary phase impregnants and chiral mobile phase modifiers, temperature, and pH on the enantioseparation result). 

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