BILE SALT SURFACTANT SYSTEMS AND THEIR UTILIZATION IN SEPARATION SCIENCE

Professor Willie L. Hinze, Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina

abstract

A brief description and overview of bile salt surfactant aggregate systems, along with some of their pertinent characteristics and properties, will first be presented. In particular, the unique features of the bile salt micelles in comparison to those formed from classical surfactants (such as sodium dodecylsulfate or hexadecyltrimethylammonium halides) which serve to enhance their importance in chemical analysis applications will be highlighted. Next, the utilization of bile salt media in separation science applications will be discussed. Specifically, bile salt aggregate systems have been successfully employed as run buffer or mobile phase additives in capillary electrophoresis and liquid chromatography for the separation of routine and isomeric organic compounds and inorganic species. The focus of the presentation will concern our use of bile salts as chiral mobile phase additives for the separation of optical isomers. In particular, use of aqueous solutions of sodium taurocholate and sodium taurodeoxycholate allows for the HPLC separation of some specific classes of enantiomers; such as binaphthol and planar compounds. The factors, such as temperature, pH, and nature and concentration of organic modifiers, which influence such chiral separations, will be discussed. In addition, some chiral separations are possible when the bile salts are added to polar organic mobile phase systems in the HPLC or TLC mode.

Some preliminary data will be presented concerning the possible use of mixed bile salt &endash; classic surfactant systems for the selective enrichment of optical isomers in an extractive procedure based on the ability of the mixed system to phase separate due to formation of coacervate phases.