Ionizable cyclodextrin derivatives, separation

In some cases, an ionic chiral micelle (e.g., a bile salt) is also used as a chiral pseudo-stationary phase with a CD. Moreover, cyclodextrin electrokinetic chromatography (CDEKC), where a CD derivative having an ionizable group is used as a chiral pseudo-stationary phase, has become popular recently since several commercially available ionic CD derivatives have appeared. Although the CDEKC technique is actually beyond the field of MEKC, it is an important method for enantiomer separation by CE. 

Anionic Cyclodextrins Anionic CDs are often carbox-yalkylated, sulfoalkylated, sulfated, and phosphorylated. The most commonly used derivatives are S-p-CD, SBE-(3-CD, and sulfoethyl ether-p-CD. " Some examples from the literature are given below. Wu et al." describe a CE method with electrospray ionization-tandem MS (ESI-MS/MS) for the quantification of 1,2,3,4-tetrahydroisoqui-noline derivatives (TlQs). They performed the enantioseparation in a 50-p,m i.d., 75-cm-long fused-silica capillary filled with a 20-mM acetic acid/ammonium acetate buffer with pH 5.5 containing 1.0-mM S- -CD. The TIQ derivatives, i.e., salsolinol, 1-benzyl-TIQ, and A/-methyl salsoli-nol, could be baseline separated with resolutions ranging from 3 (for salsolinol) to 4.5 (for 1-benzyl-TIQ). 

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