Capillary electrochromatography in anion-exchange and normal-phase mode using monolithic stationary phases.
Hydrophilic macroporous weak and strong anion-exchange stationary phases have been prepared in a monolithic format within untreated fused-silica capillaries by the simple thermally or UV-initiated polymerization of 2-dimethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate and ethylene dimethacrylate in the presence of a binary porogenic mixture of dodecanol and cyclohexanol. The tertiary amino functionalities were then alkylated in situ to afford strong anion-exchangers. These new monolithic stationary phases with optimized porous properties were used for the CEC separation of various organic anions. Thus, a mixture of 2-substituted propionic acid drugs (profens) was separated in 13 min and high column efficiencies of up to 231,000 plates/m were achieved. The separation of substituted benzoic acids indicates that the selectivity results primarily from the anion-exchange interactions, while electrophoretic migration contributes only slightly. In addition, these hydrophilic anion-exchangers are also able to separate weakly acidic, neutral and basic compounds such as phenols, xanthines and aromatic amines in normal-phase electrochromatographic mode.
Lämmerhofer
M
M
Department of Chemistry, University of California, Berkeley 94720-1460, USA.
Svec
F
F
Fréchet
J M
JM
Lindner
W
W
D000837:Anion Exchange Resins; D002852:Chromatography, Ion Exchange / Q000379:methods*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D013696:Temperature
D000837:Anion Exchange Resins