The enantiomers of five profen (PROF) drugs were simultaneously separated by MEKC with the combined use of 2, 3, 6-tri-O-methyl-β-cyclodextrin (TM-β-CD) and chiral cationic ionic liquid (IL), N-undecenoxy-carbonyl-L-leucinol bromide (L-UCLB), which formed micelles in aqueous buffers. Enantioseparations of these PROF drugs were optimized by varying the chain length and concentration of the IL surfactant using a standard recipe containing 35 mM TM-β-CD, 5 mM sodium acetate at pH 5.0. The batch-to-batch reproducibility of L-UCLB was tested and found to have no significant impact in terms of enantiomeric resolution, efficiency and migration time. Finally, this method was successfully applied for the quantitative determination of ibuprofen in pharmaceutical tablets.

A competitive inhibition mechanism is proposed to investigate the interactions among 2,3,6-tri-Omethyl-β-cyclodextrin (TM-β-CD), cationic ionic liquid (IL) type surfactants, N-undecenoxycarbonyl-L-leucinol bromide (L-UCLB) and profens (PROFs) using affinity capillary electrophoresis. The apparent binding constant of TM-β-CD to L-UCLB was estimated by nonlinear and linear plotting methods. The binding constants of one representative PROF (e.g., fenoprofen) to TM-β-CD and to L-UCLB were estimated by a secondary plotting approach. The R-and S-fenoprofen have different binding constant values, resulting in the enantioseparation due to the synergistic effect of the two chiral selectors, TM-β-CD and L-UCLB.