Chiral separation of amino acids derivatized with fluoresceine-5isothiocyanate by capillary electrophoresis and laser-induced fluorescence detection using mixed selectors of beta-cyclodextrin and sodium taurocholate.
Chiral separation of 20 pairs of amino acids derivatized with fluoresceine-5-isothiocyanate (FITC) by capillary electrophoresis and laser-induced fluorescence detection was studied using the mixture of beta-cyclodextrin (beta-CD) and sodium taurocholate (STC) as selector. Resolution was considerably superior to that obtained by using either beta-CD or STC alone. The molar ratio of beta-CD to STC of about 2:3 was found to be critical to achieve maximum separation. At this beta-CD-to-STC ratio, chiral separation occurred at really low total concentration of beta-CD and STC (<0.1 mM). Other impacting factors were investigated including the total concentration of beta-CD and STC, pH, and capillary conditioning procedure between two successive runs. Using a running buffer of 80 mM borate containing 20 mM beta-CD and 30 mM STC at pH 9.3, all of the 20 pairs of FITC-amino acid enantiomers were baseline resolved. The resolutions of the most pairs of the amino acid enantiomers (17 of 20) were higher than 3.0, only three pairs gave a resolution lower than 3.0 but higher than 1.90 (beta-phenylserine, pSer). The highest resolution reached 14.58 (Glu). Two derivatives of beta-CD, 2-hydroxypropyl-beta-CD (HP-beta-CD) and heptakis(2,6-di-O-methyl)-beta-CD (DM-beta-CD) were also explored. HP-beta-CD showed similar cooperative effect with STC, while DM-beta-CD together with STC led to poorer chiral separation.
Lu
Xiaoning
X
Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing.
Chen
Yi
Y
D000596:Amino Acids / Q000737:chemistry / Q000302:isolation & purification*; D002021:Buffers; D003505:Cyclodextrins / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000379:methods*; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007834:Lasers; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013237:Stereoisomerism; D013656:Taurocholic Acid / Q000737:chemistry*; D047392:beta-Cyclodextrins
D000596:Amino Acids; D002021:Buffers; D003505:Cyclodextrins; D047392:beta-Cyclodextrins; D013656:Taurocholic Acid; D016650:Fluorescein-5-isothiocyanate; C031215:betadex