Skip to Content
Merck
  • Separation of oxazepam, lorazepam, and temazepam enantiomers by HPLC on a derivatized cyclodextrin-bonded phase: application to the determination of oxazepam in plasma.

Separation of oxazepam, lorazepam, and temazepam enantiomers by HPLC on a derivatized cyclodextrin-bonded phase: application to the determination of oxazepam in plasma.

Journal of biochemical and biophysical methods (2003-01-25)
Chuong Pham-Huy, Géraldine Villain-Pautet, He Hua, Nassima Chikhi-Chorfi, Hervé Galons, Marc Thevenin, Jean-Roger Claude, Jean-Michel Warnet
ABSTRACT

The enantioselective high-performance liquid chromatography (HPLC) of three racemic 3-hydroxybenzodiazepines, oxazepam (Oxa), lorazepam (Lor), and temazepam (Tem), is a difficult operation because of the spontaneous chiral inversion in polar solvent. To solve this problem, we have developed an HPLC method based on a chiral Cyclobond I-2000 RSP column, maintained at 12 degrees C, and a reversed mobile phase (acetonitrile in 1% triethylamine acetate buffer, TEAA) at a flow rate of 0.4 ml/min. Peaks were detected by a photodiode-array detector at 230 nm for quantification and by an optical rotation detector for identification of (+) and (-) enantiomers. The results showed that peak resolutions of Oxa, Lor, and Tem enantiomers, analyzed under the same conditions, were 3.2, 2.0, and 1.8, respectively. For the determination of Oxa enantiomers in plasma of rabbits, extraction with diethyl ether at pH 1.5, a polar organic mobile phase, and a Cyclobond I-2000 SP column were used. Other analytical conditions were the same as previously described. Blood samples were immediately cooled at 4 degrees C and centrifuged at 0 degrees C for the collection of plasma. The results showed a difference in plasma S(+)- and R(-)-oxazepam concentrations in rabbits. No racemization of S(+)- or R(-)-Oxa enantiomers, added alone to blank plasma, was observed after extraction and enantioselective HPLC analysis.

MATERIALS
Product Number
Brand
Product Description

Supelco
Astec® CYCLOBOND I 2000 RSP Chiral HPLC Guard, Cartridge, 5 μm particle size, L × I.D. 2 cm × 4 mm
Supelco
Astec® CYCLOBOND I 2000 RSP Chiral HPLC Column, 5 μm particle size, L × I.D. 25 cm × 4.6 mm
Supelco
Astec® CYCLOBOND I 2000 Chiral HPLC Column, 5 μm particle size, L × I.D. 15 cm × 2.1 mm
Supelco
Astec® CYCLOBOND I 2000 Chiral HPLC Column, 5 μm particle size, L × I.D. 10 cm × 2.1 mm
Supelco
Astec® CYCLOBOND I 2000 Chiral HPLC Column, 5 μm particle size, L × I.D. 25 cm × 10 mm
Supelco
Astec® CYCLOBOND I 2000 Chiral HPLC Column, 5 μm particle size, L × I.D. 25 cm × 4.6 mm