Application of diaza-18-crown-6-capped β-cyclodextrin bonded silica particles as chiral stationary phases for ultrahigh pressure capillary liquid chromatography

Two bonded chiral stationary phases (CSPs), 8-aminoquinoline-2-ylmethyl- and 8-aminoquinoline-7-ylmethyl-diaza-18-crown-6-capped [3-(2-O-β-cyclodextrin)-2-hydroxypropoxy]propylsilyl silica particles (non-porous, 1.5 μm), have been prepared and evaluated using capillary liquid chromatography at high pressures (≥8000 p.s.i.). High column efficiency (up to 400 000 plates m−1) was achieved for chiral separations. These CSPs with two recognition sites, i.e. substituted-diaza-18-crown-6 and β-cyclodextrin combined with high chromatographic efficiency provide good resolution of a variety of enantiomers and positional isomers in relatively short times under reversed-phase conditions. After inclusion of a Ni (II) ion from the mobile phase, the positively charged crown ether-capped β-cyclodextrin facilitates specific static, dipolar, and host–guest complexation interactions with solutes.