No abstract

No abstract

No abstract

Anionic cyclodextrins (CDs), i.e., sulfated CD, sulfobutylether b-CD (SBE-b-CD) and heptakis(2,3-di-O-acetyl-6-sulfato)-b-CD (HDAS-b-CD), were used to separate the isomers of atropine, homatropine, ipratropium, scopolamine and butylscopolamine. Variations in the pH value and the concentration of the various CDs revealed the sulfated b-CD to be superior to the other derivatives. In a basic medium at low concentrations of sulfated CD the enantiomers of atropine, homatropine and ipratropium were well resolved in a short migration time, which is appropriate for the routine analysis of the enantiomeric excess. Scopolamine and butylscopolamine compounds could not be separated with either CD.

Beta-cyclodextrin (beta-CD), heptakis(2,3-di-O-acetyl)beta-cyclodextrin (Diac-beta-CD) and heptakis (2,3-di-O-acetyl-6-sulfato)beta-cyclodextrin (HDAS-beta-CD) were tested for their ability to discriminate the enantiomers of ephedrine, pseudoephedrine, norephedrine and methylephedrine. Using capillary electrophoresis (CE) under optimized conditions, with the exception of norephedrine in presence of beta-CD, all racemates could be resolved. Utilizing Job's plot by means of UV spectroscopy revealed 1:1 complexes formed with beta-CD and Diac-beta-CD. HDAS-beta-CD gave curved plots indicating mixed stoichiometry. Inspection of the cyclodextrin-induced chemical shifts (CICS) of both the ligands and the CDs showed that the ephedrine sits deeply in the cavity of beta-CD and HDAS-beta-CD. In the case of Diac-beta-CD, the ephedrine is located closely to the wider rim of the CD cavity. In conclusion, comparing the pattern of CICS of the various CD derivatives clearly indicates the differences in the complex geometry.