L. Mateus et al., Enantioseparation of atropine by capillary electrophoresis using sulfated beta-cyclodextrin: application to a plant extract, J CHROMAT A, 868(2), 2000, pp. 285-294
A capillary zone electrophoresis (CZE) method, with sulfated P-CD as chiral
selector, was optimized by means of an experimental design for the enantio
separation of atropine. In this study, a central composite design was used
and the following factors were varied simultaneously: buffer concentration,
buffer pH and sulfated P-CD concentration. The resolutions between littori
ne and its positional isomer ((-)-hyoscyamine) and between atropine enantio
mers, as well as the separation time and generated current were established
as responses. A model was obtained for each response by linear multiple re
gression of a second-degree mathematical expression. The most favorable con
ditions were determined by maximizing the resolution between atropine enant
iomers and by setting the other responses at threshold values. Successful r
esults 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 wa
s 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 demonstr
ated that supercritical fluid extraction induced less racemization than cla
ssical liquid-solid extraction procedures. (C) 2000 Elsevier Science B.V. A
ll rights reserved.