β-Cyclodextrin-hexamethylene diisocyanate copolymer-coated zirconia for separation of racemic 2,4-dinitrophenyl amino acids in reversed-phase liquid chromatography

We report use of β-cyclodextrin (CD)-hexamethylene diisocyanate (HMDI) copolymer(CDPU)-coated zirconia (CDPUZ) as a chiral stationary phase for separation of enantiomers of a set of 2,4-dinitrophenyl (DNP) amino acids in reversed-phase liquid chromatography. The effects of polymer loading on zirconia and HMDI/CD molar ratio in the preparation of CDPU on retention and selectivity in the separation of DNP-amino acids in were examined to find optimum polymer loading and HMDI/CD ratio. It was observed that 8% loading of the CDPU prepared with the HMDI/CD molar ratio of 4 gave the best separation of the amino acids investigated. Retention and chiral selectivity of CDPUZ were also compared to those for previously reported carboxymethyl-β-CD-coated zirconia (CMCDZ). CDPUZ gave better chiral separation than CMCDZ for the DNP-amino acids.