[Chiral separation by capillary electrochromatography on stationary phase adsorbed with protein]

A method based on the adsorption of bovine serum albumin (BSA) on the strong anion-exchange packing (SAX) was applied to prepare chiral stationary phases for capillary electrochromatography. It was found that the electroosmotic mobility only decreased 26.3% when the BSA was adsorbed. The run-to-run reproducibilities of void time and the migration times of D- and L-tryptophan enantiomers were rather good with the relative standard deviation (RSD) values of 0.90%, 0.87% and 0.96%, respectively, when mobile phase containing 7% (volume fraction) acetonitrile. The merit of this system is that the direction of electroosmotic flow is still from cathode to anode, preferable to separate acidic enantiomers. Four anionic enantiomers, tryptophan, ketoprofen, fenoprofen and warfarin, as well as the neutral enantiomers of benzoin were successfully resolved. In order to reduce the analysis time, n-hexanoic acid was added to the mobile phase as a competitive agent. The effect of acetonitrile volume fraction on the resolution of enantiomers was also investigated.