Capillary Zone Electrophoresis of Bile Acids with Indirect Photometric Detection

Investigations in our laboratory have demonstrated that capillary zone electrophoresis (CZE) with indirect photometric detection is a viable approach to the separation and identification of free bile acids along with their taurine and glycine derivatives. Various parameters such as pH, organic solvent concentrations, column temperature, and type of chromophore electrolyte were investigated to optimize the electrophoretic separation and to maximize the peak capacity. The quality of separation of bile acids can be dramatically improved by incorporating γ-cyclodextrin (γ-CD) in the running electrolyte. This improvement in resolution is accompanied by a decreased migration time, suggestive of an increase in association of γ-CD with bile acids. As a result, a CZE separation of all 15 bile acids was possible in ∼30 min using 5 mM adenosine 5‘-monophosphate, 7 mM γ-CD in 75% (v/v) methanol at pH 7.0.