S. Fanali et al., Use of MDL63246 (Hepta-Tyr) antibiotic in capillary zone electrophoresis -II. Chiral resolution of alpha-hydroxy acids, J CHROMAT A, 838(1-2), 1999, pp. 223-235
The glycopeptide antibiotic MDL 63 246 (Hepta-Tyr), belonging to the teicop
lanin family, has been adopted for the separation of several cr-hydroxy aci
d enantiomers by capillary zone electrophoresis (CZE). A polyacrylamide coa
ted capillary was employed for the electrophoretic runs in order to suppres
s/minimize both the electroosmotic flow (EOF) and the antibiotic adsorption
. The experiments were carried out using a background electrolyte (BGE) (aq
ueous-organic buffer) in the pH range 1-6 that allowed the analytes to reac
h the detector, as negatively charged species, in a relatively short time w
hile the antibiotic moved in the opposite direction (positively charged). T
he chiral selector, dissolved in the BGE at relatively low concentration, f
illed only part of the capillary (partial filling-counter current method) a
llowing the detection of analytes with good sensitivity and short analysis
time (5-8 min). Experimental parameters influencing the enantioresolution s
uch as antibiotic concentration, buffer pH, organic modifier type and conce
ntration and capillary temperature were investigated. Hepta-Tyr antibiotic
exhibited a high enantiorecognition capability towards mandelic acid and th
eir hydroxy and chloro derivatives even at very low concentration (1 mg/ml)
using a background electrolyte (BGE) at pH 4 containing 20% (v/v) of metha
nol. On the other hand 2- and 3-phenyllactic acids were baseline resolved i
n their enantiomers with the same BGE containing acetonitrile and 4 mg/ml o
f chiral selector. (C) 1999 Elsevier Science B.V. All rights reserved.