Preparation and evaluation of diureido bridged β-cyclodextrin-bonded chiral stationary phase by high-performance liquid chromatography

A diureido bridged beta-cyclodextrin dimer was synthesized by the reaction of 6-deoxy-6-hydroxyethylamino-beta-cyclodextrin with hexamethylene diisocyanate. The dimer was then bonded onto silica to obtain a novel diureido bridged beta-cyclodextrin-bonded stationary phase (UBCDP). The structure of diureido bridged stationary phase was characterized by infrared spectroscopy, mass spectrometry, and elemental analysis. By using racemic drugs and pesticides as probes (flavanones, triazoles, and dansylated amino acids), the chromatographic properties of UBCDP were evaluated. The separation mechanism was elucidated by comparison with a single beta-cyclodextrin chiral stationary phase (CDCSP). The composition, pH value of the mobile phase and column temperature were optimized. The results showed that the UBCDP can resolve 25 chiral compounds, especially 2'-hydroxyflavanone, hexaconazole and dansyl leucine with high resolutions (R-s, 1.52-4.35), and the larger volume hesperidin could also be separated. This trend was related to the synergistic inclusion of bridged cyclodextrins. CDCSP can separate only a small number of enantiomers with low resolutions. UBCDP exhibited better enantio-separation ability and hence had potential application in chiral drugs and chiral pesticide residues analysis.