[Chiral separation of naproxen and flurbiprofen by capillary electrophoresis]

The acidic chiral drugs naproxen and flurbiprofen were successfully separated into two enantiomers when beta-cyclodextrins (beta-CDs) were used as chiral selectors by capillary zone electrophoresis, under the conditions of 0.1 mol/L phosphate buffer with pH 4.92. The comparison of four CDs, namely beta-CD, DM-beta-CD, HP-beta-CD and TM-beta-CD for chiral separation was made. Naproxen can be separated by either beta-CD or its derivatives, while flurbiprofen can only be separated by TM-beta-CD among the CDs. The elution order of enantiomers of naproxen in different CDs was also studied, and the R form always eluted before S form when any of the four CDs was used as chiral selectors. The method of chiral separation for weak acidic compounds was also developed. It was proved that the optimum pH value for their chiral separation was about 5, close to its pKa value.