title: [Analysis of impurity in caderofloxacin].
abstract: OBJECTIVE
  To analyse the main impurity of caderofloxacin.
  
  
  METHODS
  The impurity of caderofloxacin was analysed and determinated by RP-HPLC/ESI/MS with a Zorbax SB-C18 (150 mm x 4.6 mm ID, 5 microns) column. The mobile phase was acetonitrile-0.5% acetic acid solution (17:83). A compound was synthesized: 1-cyclopropyl-8-(difluoromethoxy)-6-fluoro-1, 4-dihydro-7-(1-piperazinyl)-4-oxo-3-quinoline carboxylic acid (DMCA). Its HPLC chromatogram, UV and MS spectrum were compared with those of the impurity in caderofloxacin.
  
  
  RESULTS
  The molecular weight of the impurity was 14 less than that of caderofloxacin. It means the impurity was a CH2-group less than caderoflixacin. The tR, UV and MS of DMCA were the same as those of the impurity in caderofloxacin.
  
  
  CONCLUSIONS
  Based on the tR (HPLC), UV and MS, the impurity of caderofloxacin is confirmed as DMCA.
authors.affiliation: Center for Instrumental Analysis, China Pharmaceutical University, Nanjing 210009, China. marenling@sohu.com
authors.forename: Ren-ling
authors.initials: RL
authors.lastname: Ma
authors.forename: Hong-hua
authors.initials: HH
authors.lastname: Zhou
authors.forename: Rong
authors.initials: R
authors.lastname: Liu
authors.forename: Er-hua
authors.initials: EH
authors.lastname: Wang
authors.forename: Long-sheng
authors.initials: LS
authors.lastname: Sheng
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry*; D002264:Carboxylic Acids / Q000032:analysis* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004340:Drug Contamination; D024841:Fluoroquinolones / Q000737:chemistry*; D015394:Molecular Structure; D010879:Piperazines / Q000737:chemistry*; D011804:Quinolines / Q000032:analysis* / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: C489705:1-cyclopropyl-8-(difluoromethoxy)-6-fluoro-1, 4-dihydro-7-(1-piperazinyl)-4-oxo-3-quinoline carboxylic acid; D000890:Anti-Infective Agents; D002264:Carboxylic Acids; D024841:Fluoroquinolones; D010879:Piperazines; D011804:Quinolines; C097449:CS 940