Home  About us  Contact
 

Homoamino Acids (homoamino + acid)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

HPLC enantioseparation of ,2 -homoamino acids using crown ether-based chiral stationary phase

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 7 2009
Róbert Berkecz
Abstract RP high-performance liquid chromatographic methods were developed for the enantioseparation of eleven unusual ,2 -homoamino acids. The underivatized analytes were separated on a chiral stationary phase containing (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid as chiral selector. The effects of organic (alcoholic) and acidic modifiers, the mobile phase composition and temperature on the separation were investigated. The structures of the substituents in the ,-position of the analytes substantially influenced the retention and resolution. The elution sequence was determined in some cases: the S enantiomers eluted before the R enantiomers. [source]

High-performance liquid chromatographic chiral separation of ,2 -homoamino acids

CHIRALITY, Issue 9 2009
Zoltán Pataj
Abstract Reversed-phase high-performance liquid chromatographic methods were developed for the separation of enantiomers of eleven unnatural ,2 -homoamino acids on chiral stationary phases containing macrocyclic glycopeptides (teicoplanin-containing Chirobiotic T and T2) or the macrocyclic peptide teicoplanin aglycone (Chirobiotic TAG) as chiral selectors. The effects of the organic modifier, the mobile phase composition, temperature, and the structures of the analytes on the separations were investigated. Separations were carried out at constant mobile phase compositions in temperature range 7,45°C and the changes in enthalpy, ,(,H°), entropy, ,(,S°), and free energy, ,(,G°), were calculated. The ,,(,G°) values obtained on the three columns indicated that Chirobiotic TAG, without sugar units, may promote the interactions of the enantiomers of ,2 -homoamino acids with branched alkyl or aryl side-chains, whereas for ,2 -homoamino acids with alkyl side-chains Chirobiotic T and T2 seem to be more favorable. The elution sequence was determined in some cases and was observed to be R < S. Chirality, 2009. © 2008 Wiley-Liss, Inc. [source]