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Titolo:
Apparent and true enantioselectivity in enantioseparations
Autore:
Gotmar, G; Fornstedt, T; Guiochon, G;
Indirizzi:
Univ Tennessee, Dept Chem, Knoxville, TN 37996 USA Univ Tennessee Knoxville TN USA 37996 Dept Chem, Knoxville, TN 37996 USA Dept Pharm, Uppsala, Sweden Dept Pharm Uppsala SwedenDept Pharm, Uppsala, Sweden Oak Ridge Natl Lab, Div Chem & Analyt Sci, Oak Ridge, TN 37831 USA Oak Ridge Natl Lab Oak Ridge TN USA 37831 yt Sci, Oak Ridge, TN 37831 USA
Titolo Testata:
CHIRALITY
fascicolo: 7, volume: 12, anno: 2000,
pagine: 558 - 564
SICI:
0899-0042(2000)12:7<558:AATEIE>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
CHIRAL STATIONARY PHASE; CBH-I-SILICA; PROPRANOLOL ENANTIOMERS; ALPHA-1-ACID GLYCOPROTEIN; LIQUID-CHROMATOGRAPHY; RETENTION MECHANISMS; ADSORPTION BEHAVIOR; CELLULASE PROTEIN; SEPARATION; RESOLUTION;
Keywords:
retention mechanisms; enantioselectivity; apparent enantioselectivity; true nonselective interactions beta-blockers;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
25
Recensione:
Indirizzi per estratti:
Indirizzo: Guiochon, G Univ Tennessee, Dept Chem, Knoxville, TN 37996 USA Univ Tennessee Knoxville TN USA 37996 Knoxville, TN 37996 USA
Citazione:
G. Gotmar et al., "Apparent and true enantioselectivity in enantioseparations", CHIRALITY, 12(7), 2000, pp. 558-564

Abstract

The separation factor of two compounds in chromatography is the ratio of their equilibrium constants or retention factors. This parameter is universally employed to investigate their resolution and to optimize the experimental conditions of their analysis. In enantioseparations, the situation is more complex because there is a mixed retention mechanism. The retention factor is the sum of two contributions, one enantioselective, the other nonselective. Although both contribute to retention, the latter being identical for the two enantiomers and does not contribute to their separation. We show how these two contributions can be measured and how it becomes necessary todistinguish between the apparent, a(app), and the true, alpha(true), separation factors. The existence of nonselective sites is responsible for a(app) being less than alpha(true). Depending on the difference between these two factors, the more effective approach to improve a separation is either toincrease the enantioselectivity or to reduce the nonselective interactions. Practical applications to separations of different beta-blockers on cellobiohydrolase are discussed. The apparent enantioselectivity of alprenolol is larger and increases faster with increasing pH than that of the more hydrophobic propranolol, in spite of the importance of hydrophobic interactionsin the enantioselective mechanism. These two unexpected properties are discussed and explained. (C) 2000 Wiley-Liss.

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Documento generato il 04/04/20 alle ore 02:11:12