S. Fanali et al., Enantioseparation of S-carboxymethylcysteine and N-acetamidocarboxymethylcysteine by capillary electrophoresis using vancomycin, J SEP SCI, 24(9), 2001, pp. 789-794
Racemic S-carboxymethylcysteine (DF-1794Y) and N-acetamido S-carboxymethyl
cysteine (DF-1796A) were resolved into their enantiomers by capillary elect
rophoresis using vancomycin as a chiral selector. Electrophoretic runs were
carried out in a polyacrylamide-coated capillary filled with a background
electrolyte composed of sorbic acid/histidine (pH = 4.5-6.5) and the approp
riate concentration of vancomycin. The presence of the chiral selector (CS)
in the detector path was avoided by using the partial filling-countercurre
nt method, where the CS filled only part of the capillary and was moving in
the opposite direction to the analytes. Due to the relatively low absorpti
on of the enantiomers studied, indirect UV detection was used in order to i
ncrease the sensitivity of the method. For method optimization the effect o
f several experimental parameters such as vancomycin concentration, buffer
pH, and organic modifier type and concentration on enantioresolution and mi
gration time were studied. The migration order was verified only for S-carb
oxymethylcysteine by injecting a mixture containing the racemic DF-1794Y sp
iked with the enantiomer S-carboxymethyl-L-cysteine. The L-isomer was found
to migrate first.