Combined use of chiral ionic liquid and CD for MEKC: Part II. Determination of binding constants.

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