Chiral Separations by Micellar Electrokinetic Chromatography - Chiral Separations by Capillary Electrophoresis - page 210

i rst. Employing the same mixed micelle system in the presence of 10% methanol
and 5 M urea six PTH-amino acids were enantioseparated simultaneously along with
warfarin and benzoin [163,164]. It was also demonstrated that the addition of SDS,
urea, methanol, and 2-propanol to each of the chiral surfactant solution of sodium
N -dodecanoyl-l-serinate (SDSer), sodium N -dodecanoyl-l-aspartate (SDAsp), and
sodium N -tetradecanoyl-l-glutamate (STGlu) was essential for the improvement of
enantioselectivity and peak shapes in chiral analysis of PTH-amino acids [144,165].
The addition of bile salts to the aqueous solutions of polyoxyethylene ethers
(PEs; C 12 E 4 , C 12 E 6 , C 10 E 8 ) have been reported by Clothier et al. [166,167] to improve
enantiomeric separations of verapamil and related compounds by MEKC. In one
experiment, mixtures of SDC and three PEs were evaluated. In another investiga-
tion, chiral resolving abilities of micellar solutions of four different bile salts alone
and in mixtures with C 12 E 4 and methanol were studied. The addition of C 12 E 4 to
the solutions of SC and SDC with or without methanol improved chiral resolution
for compounds containing longer hydrocarbon chain, there by separating the chiral
center from the major functional groups. Following the same method, enantiomeric
separations of three binaphthyl derivatives were performed using the combination of
SC and SDC surfactants with SDS [168]. Recently, Park and Jung [169] performed
enantioseparations of some chiral l avonoids by MEKC using SDS micelles in the
presence of microbial cyclosophoraoses and their sulfated derivatives.
Zhao et al. [170] demonstrated the utility of abietic acid, a naturally occur-
ring chiral derivatizing agent, through separations of diastereomers of 10

TABLE 8.2
Chiral Separations by MEKC Using Mixed Chiral and Achiral
Surfactant Systems

Chiral Surfactant Achiral Surfactant Additives Separated Enantiomers

SC or SDC Brij 30 Methanol Atenolol, verapamil,

norverapamil, BOH,
gallopamil, BAYK8644

SDC Brij 30 Urea Verapamil, gallopamil,

norverapamil,

STDC Brij 30 Bupivacaine, prilocaine

mepivacaine

Octyl-β-d-glucoside SDS, GRA DNS-amino acids

SDS PTH-amino acids

β-Escin

SDV SDS Methanol, urea PTH-amino acids

SDV Methanol, urea PTH-amino acids

SDV SDS PTH-amino acids, benzoin,

warfarin

SDGlu SDS Urea, methanol/

isopropanol

PTH-amino acids, benzoin

SDSer SDS Methanol PTH-amino acids

STGlu SDS PTH-amino acids