Pharmaceutical applications using cholesteryl-10-undecenoate bonded phase in microcolumn liquid chromatography

The separation behaviors of four different groups of pharmaceuticals were i nvestigated using cholesteryl-10-undecenoate and ODS phases. The cholestery l phase, which has liquid crystal properties, showed different selectivity and retention behavior from those of ODS phase. The difference is on its ap parent ability to recognize specific structures in the molecules, discrimin ate among derivatives, or subsequently recognize modifications done on thes e structures. However, on ODS phase the hydrophobicity effects seem to take precedent as the main factor in its retention mechanism. This enhanced sel ectivity of the cholesteryl phase is attributed to three contributing struc tures found in its structure; the long hydrocarbon chain that gives added m obility to the phase, the carbonyl group which can interact with a variety of substituent groups, and the cholesteric moiety which can invoke pi-pi in teraction as well as steric effects. The use of the cholesteryl phase for t hese kinds of pharmaceutical analyses is therefore warranted and showed int eresting possibilities for future applications.