Enantioseparation of 3,4-dihydroxyphenylalanine and 2-hydrazino-2-methyl-3-(3,4-dihydroxyphenyl)propanoic acid by capillary electrophoresis using cyclodextrins.
The enantiomeric separations of 3,4-dihydroxyphenylalanine (dopa) and 2-hydrazino-2-methyl-3-(3,4-dihydroxyphenyl)propanoic acid (carbidopa) by capillary electrophoresis were studied using several native, neutral and anionic cyclodextrins as chiral additives and uncoated fused-silica capillaries. The effect of the type and concentration of the cyclodextrin added to 20 mM phosphate buffer (pH 2.5) on enantioseparation and migration times was studied. A high resolution value of 15.63 was obtained for dopa enantiomers with a buffer containing 20 mM single isomer, heptakis(2,3-diacetyl-6-sulfato)-beta-cyclodextrin. The enantiomers of carbidopa were separated using 20 mM carboxymethyl-beta-cyclodextrin as a chiral resolving agent. Both methods allowed the determination of 0.1% of the D-enantiomer (second migrating) in the presence of the L-enantiomer (first migrating) of dopa and carbidopa with a good precision. These methods also gave good results in terms of precision for both peak area, migration time, linearity and accuracy.
Saraç
S
S
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey.
Chankvetadze
B
B
Blaschke
G
G
D002230:Carbidopa / Q000737:chemistry / Q000302:isolation & purification*; D003505:Cyclodextrins / Q000737:chemistry*; D004295:Dihydroxyphenylalanine / Q000737:chemistry / Q000302:isolation & purification*; D019075:Electrophoresis, Capillary / Q000379:methods*; D013237:Stereoisomerism
D003505:Cyclodextrins; D004295:Dihydroxyphenylalanine; D002230:Carbidopa