title: [Rapid identification of the isomeric impurity in raw drug of cefepime dihydrochloride by liquid chromatography-tandem mass spectrometry].
abstract: OBJECTIVE
  To establish a sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of isomeric impurity in raw drug material of cefepime dihydrochloride.
  
  
  METHODS
  The HPLC separation experiments were performed on a reversed phase C18 column, with acetonitrile-10 mmol x L(-1) ammonium acetate (5:95) as mobile phase (a flow rate of 0.8 mL x min(-1)). The analytes were determined by electrospray ionization tandem mass spectrometry in positive mode. The chromatogram and mass spectra of cefepime dihydrocloride and its isomeric impurity were obtained by LC-MS/MS.
  
  
  RESULTS
  The method can be used for the separation and identification of cefepime dihychrocloride and its isomeric impurity, of which the retention times were 15.28 min and 9.18 min, respectively. Based on the MS/MS spectra of their molecular ions, the different fragmentation pathways of cefepime dihydrocloride and its isomeric impurity were compared and proposed.
  
  
  CONCLUSIONS
  The method was rapid, sensitive and specific. It can be used for the identification of the isomeric purity in raw drug material of cefepime dihydrochloride.
authors: Institute of Pharmacology and Toxicology, Academy of Military Medical Science, Beijing 100850, China.
authors: Ling
authors: L
authors: Zhao
authors: Ji-fen
authors: JF
authors: Guo
authors: Ai-jun
authors: AJ
authors: Zhang
authors: Yi-min
authors: YM
authors: Zhao
mesh_terms: D000077723:Cefepime; D002511:Cephalosporins / Q000737:chemistry / Q000302:isolation & purification*; D002853:Chromatography, Liquid / Q000379:methods; D004340:Drug Contamination; D007536:Isomerism; D011786:Quality Control; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D002511:Cephalosporins; D000077723:Cefepime