SEPARATION OF TRAMADOL ENANTIOMERS BY CAPILLARY ELECTROPHORESIS USING HIGHLY SULFATED CYCLODEXTRINS

In the pharmaceutical industry a continuing need for chiral resolution of drugs for various purposes and indiverse matrices exist. For these reasons, analysts may require a number of different separation systemscapable of resolving a given pair of enantiomers. Highly sulfated cyclodextrins (HS-CDs) represent arelatively new class of chiral selectors in capillary electrophoresis (CE). In this investigation the use ofHS-CDs as chiral selectors in CE for enantioseparation of tramadol, a highly potent analgesic, as themodel drug and the influence of the type of selector and its concentration on enantiomeric resolution werestudied. All of the available HSCDs ( α,β and γ) could resolve tramadol enantiomers, but HS-γ-CDshowed better resolution and a baseline resolution was achieved with this selector even at a concentrationas low as 0.5% w/v. Additionally, effect of the buffer pH on the enantioresolution was studied. At low pHbuffers, in which electroosmotic flow is low in CE, the negatively charged selector prevented the cationictramadol to migrate out of the capillary even after a long analysis time of 60 minutes. However, at higherpH values (pH=7 or more), the electroosmotic flow is high enough to drag drug-selector complex towardthe detector and a reasonable of the enantiomers of the drug was achieved.