Application of carboxymethyl-beta-cyclodextrin as a chiral selector in capillary electrophoresis for enantiomer separation of selected neurotransmitters

The aim of this work was to optimize conditions for capillary electrophores is separation of different neurotransmitters (serotonin, phenylalanine, dop amine, adrenaline, ephedrine, propranolol and DOPA) in a single run, includ ing separation of existing enantiomers. As chiral selectors added to the bo rate background, electrolyte unsubstituted alpha-, beta- and gamma -cyclode xtrins (CDs), methyl-, dimethyl-, and trimethyl-substituted beta -CDs, and hydroxypropyl-substituted alpha-, beta- and gamma -CDs were examined. Also carboxymethyl-beta -CD and succinyl-beta -CD were used for this purpose. In addition to the kind and concentration of chiral selector, some other expe rimental factors also have been optimized, such as concentration of borate buffer, content of methanol, pH of electrolyte, method of sample introducti on into the capillary and washing procedure between consecutive runs. The b est results were obtained using 20 trild carboxymethyl-beta -CD in borate b uffer of pH 7.5 as running electrolyte and hydrostatic injection. The obtai ned sensitivity of response (peak height) varied from 0.4 for adrenalines t o 2.3 mAU mM(-1) for propranolols. The concentration detection limits (S/N= 3) were in the range from 0.04 mM for propranolols to 0.2 mM for adrenaline s. The resolution obtained in optimized conditions in a single run was from 0.75 for adrenalins and 1.0 for propranolols up to 2.0 for ephedrines. The developed method was employed for determination of these analytes in brain tissue extracts. (C) 2001 Elsevier Science B.V. All rights reserved.