Enantioseparation of atropine by capillary electrophoresis using sulfated beta-cyclodextrin: application to a plant extract.
A capillary zone electrophoresis (CZE) method, with sulfated beta-CD as chiral selector, was optimized by means of an experimental design for the enantioseparation of atropine. In this study, a central composite design was used and the following factors were varied simultaneously: buffer concentration, buffer pH and sulfated beta-CD concentration. The resolutions between littorine and its positional isomer ((-)-hyoscyamine) and between atropine enantiomers, as well as the separation time and generated current were established as responses. A model was obtained for each response by linear multiple regression of a second-degree mathematical expression. The most favorable conditions were determined by maximizing the resolution between atropine enantiomers and by setting the other responses at threshold values. Successful results were obtained with a 55 mM phosphate buffer at pH 7 in the presence of 2.9 mM sulfated-beta-CD at 20 degrees C and 20 kV. Under these optimized conditions, a baseline separation of littorine and atropine enantiomers was achieved in less than 5 min. Finally, the method allowed the enantiomeric separation of atropine in a pharmaceutical formulation and was also found to be suitable for the enantiomeric purity evaluation of (-)-hyoscyamine in plant extracts, in relation with the extraction procedure. It was demonstrated that supercritical fluid extraction induced less racemization than classical liquid-solid extraction procedures.
Mateus
L
L
Laboratory of Pharmaceutical Analytical Chemistry, University of Geneva, Switzerland.
Cherkaoui
S
S
Christen
P
P
Veuthey
J L
JL
D001285:Atropine / Q000302:isolation & purification*; D003505:Cyclodextrins / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000379:methods*; D010936:Plant Extracts / Q000302:isolation & purification*; D013237:Stereoisomerism; D013431:Sulfates / Q000737:chemistry; D047392:beta-Cyclodextrins
D003505:Cyclodextrins; D010936:Plant Extracts; D013431:Sulfates; D047392:beta-Cyclodextrins; D001285:Atropine; C031215:betadex