Titre du document / Document title

Dynamic micellar electrokinetic chromatography. Determination of the enantiomerization barriers of oxazepam, temazepam, and lorazepam

Auteur(s) / Author(s)

SCHOETZ Gabriele ⁽¹⁾ ; TRAPP Oliver ⁽¹⁾ ; SCHURIG Volker ⁽¹⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾ Universität Tübingen, Institut für Organische Chemie, Auf der Morgenstelle 18, 72076 Tübingen, ALLEMAGNE

Résumé / Abstract

The temperature-dependent enantiomerization barriers of oxazepam, temazepam, and lorazepam have been determined between 0 and 30 °C by dynamic micellar electrokinetic chromatography (DMEKC) in an aqueous 20 mM borate/phosphate buffer system at pH 8 with 60 mM sodium cholate as chiral surfactant. Interconversion profiles featuring plateau formation and peak broadening were observed and simulated by the new program Chrom Win based on the theoretical plate as well as on the stochastic model using the experimental data plateau height, h_plateau, peak width at half-height, W_h, total retention times, t_R, and electroosmotic breakthrough time, to. Peak form analysis yielded rate constants k and kinetic activation parameters, ΔG^, ΔH^, and ΔS^, of the enantiomerization of oxazepam, temazepam, and lorazepam. At 25 °C, the enantiomerization barrier, ΔG^, was determined to be ∼90 kJ mol^-1 and the half-lives, r, were determined to be approximately 21 min. The new approach allows the fast and precise determination of enantiomerization barriers in a biogenic environment and it mimics physiological conditions, as no organic modifiers or abiotic chiral stationary phases (CSP) are employed.

Revue / Journal Title

Analytical chemistry   ISSN 0003-2700   CODEN ANCHAM 

Source / Source

2000, vol. 72, n^o13, pp. 2758-2764 (34 ref.)

Langue / Language

Anglais

Editeur / Publisher

American Chemical Society, Washington, DC, ETATS-UNIS  (1947) (Revue)

Mots-clés anglais / English Keywords

Chemical analysis ; Multicomponent analysis ; Qualitative analysis ; Enantiomerization ; Benzodiazepine derivatives ; Anticonvulsant ; Tranquillizer ; Psychotropic ; Hypnotic ; Sedative ; Oxazepam ; Temazepam ; Lorazepam ; Micellar electrokinetic capillary chromatography ; Ultraviolet detector ; Physicochemical properties ; Activation parameter ; Separation capacity ; Retention factor ; Enantioselectivity ; Concentration effect ; Temperature effect ;

Mots-clés français / French Keywords

Analyse chimique ; Analyse multiélément ; Analyse qualitative ; Enantiomérisation ; Benzodiazépine dérivé ; Anticonvulsivant ; Tranquillisant ; Psychotrope ; Hypnotique ; Sédatif ; Oxazépam ; Témazépam ; Lorazépam ; Chromatographie MECC ; Détecteur UV ; Propriété physicochimique ; Paramètre activation ; Pouvoir séparation ; Facteur rétention ; Enantiosélectivité ; Effet concentration ; Effet température ;

Mots-clés espagnols / Spanish Keywords

Análisis químico ; Análisis multielemento ; Análisis cualitativo ; Enantiomerización ; Benzodiazepina derivado ; Anticonvulsivante ; Tranquilizante ; Psicotropo ; Hipnótico ; Sedante ; Oxazepam ; Temazepam ; Lorazepam ; Cromatografía MECC ; Detector UV ; Propiedad fisicoquímica ; Parámetro activación ; Poder separación ; Factor retención ; Enantioselectividad ; Efecto concentración ; Efecto temperatura ;

Localisation / Location

INIST-CNRS, Cote INIST : 120 B, 35400009140113.0170