title: Separation of Ofloxacin and Its Six Related Substances Enantiomers by Chiral Ligand-Exchange Chromatography.
abstract: A chiral ligand-exchange high-performance liquid chromatography method was developed for the enantioseparation of ofloxacin and its six related substances termed impurities A, B, C, D, E, and F. The separation was performed on a conventional C18 column. Different organic modifiers, copper salts, amino acids, the ratio of Cu(2+) to amino acid, pH of aqueous phase, and column temperature were optimized. The optimal mobile phase conditions were methanol-water systems consisting of 5 mmol/L copper sulfate and 10 mmol/L L-isoleucine (L-Ile). Under such conditions, good enantioseparation of ofloxacin and impurities A, C, E, and F could be observed with resolutions (RS ) of 3.54, 1.97, 3.21, 3.50, and 2.12, respectively. On the relationship between the thermodynamic parameters and structures of analytes, the mechanism of chiral recognition was investigated. It was concluded that ofloxacin and impurities A, C, E, and F were all enthalpically driven enantioseparation and that low column temperature was beneficial to enantioseparation. Furthermore, the structure-separation relationship of these analytes is also discussed.
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang Liaoning Province, P.R. China.
authors.forename: Xinlei
authors.initials: X
authors.lastname: Liang
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang Liaoning Province, P.R. China.
authors.forename: Longshan
authors.initials: L
authors.lastname: Zhao
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang Liaoning Province, P.R. China.
authors.forename: Miaoduo
authors.initials: M
authors.lastname: Deng
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang Liaoning Province, P.R. China.
authors.forename: Lijie
authors.initials: L
authors.lastname: Liu
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang Liaoning Province, P.R. China.
authors.forename: Yongfu
authors.initials: Y
authors.lastname: Ma
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang Liaoning Province, P.R. China.
authors.forename: Xingjie
authors.initials: X
authors.lastname: Guo
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003300:Copper / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015242:Ofloxacin / Q000737:chemistry / Q000302:isolation & purification*; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D003300:Copper; D015242:Ofloxacin
keywords: chiral ligand-exchange chromatography; chiral separation mechanism; enantioseparation; enthalpically driven; ofloxacin and its six related substances