Chiral separations using bile salts in capillary electrophoresis

Micellar electrokinetic capillary chromatography (MECC) using surfactant solutions containing bile salts, polyoxyethylene ethers and methanol was used to produce chiral separations. A capillary electrophoresis instrument was assembled in the laboratory. Initial testing and optimization of the instrument involved the separation of organic acids using capillaries zone electrophoresis techniques. Polymer coated capillaries were prepared and tested in the instrument. Bile salt solutions were characterized by viscosity and nuclear magnetic resonance. The effects of various solution conditions, such as pH, ionic strength and concentration of bile salt solutions on chiral resolution were investigated by MECC. Enhancement in chiral resolution was obtained using additives such as polyoxyethylene ethers and methanol in bile salt micellar solutions. Fluorescence spectroscopy using pyrene as a probe was utilized to determine the relative hydrophobicities of the aggregates formed in solutions containing mixtures of bile salt and polyoxyethylene ether. Correlations between micellar hydrophobicity for these solutions and chiral resolution for bi-2-naphthol, verapamil, norverapamil, gallopamil and BAYK8644 are presented