Capillary Electrophoresis of Clenbuterol Enantiomers and NMR Investigation of the Clenbuterol/Carboxymethyl- -cyclodextrin Complex

Abstract

A capillary electrophoretic method has been established for the separation of the enantiomers of clenbuterol. The effects of pH value, composition of the background electrolyte, concentration of carboxymethyl-β-cyclodextrin (CM-β-CD), capillary temperature and running voltage have been investigated. The two enantiomers were separated in an uncoated capillary with phosphate buffer (50 mmol/L, pH 3.5) containing 10 mmol/L CM-β-CD. The capillary temperature was at 15°C and applied voltage was at 20 kV. The inclusion complex of CM-β-CD and clenbuterol was synthesized and characterized by two-dimensional rotating frame spectroscopy (2D ROESY). Based on the 2D ROESY analysis, an inclusion structure of the clenbuterol/CM-β-CD complex was proposed, in which clenbuterol penetrated CM-β-CD in a tilted manner due to the interaction of intermolecular hydrogen bonds between clenbuterol and CM-β-CD.

Chirality of β2-agonists. An overview of pharmacological activity, stereoselective analysis, and synthesis

“…The CM-β-CD as a chiral selector was utilized for the enantiomeric separation of clenbuterol [135] and the other five β 2 -agonists. The optimal separation was obtained using the following buffer: 50 mM phosphonic acid with 10 mM CD at pH 3.5 [136].…”