Rapid identification of the isomeric impurity in raw drug of cefepime dihydrochloride by liquid chromatography-tandem mass spectrometry

AimTo 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. MethodsThe HPLC separation experiments were performed on a reversed phase C₁₈ column, with acetonitrile-10 mmol·L^-1 ammonium acetate (5∶95) as mobile phase (a flow rate of 0.8 mL·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. ResultsThe 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. ConclusionThe method was rapid, sensitive and specific. It can be used for the identification of the isomeric purity in raw drug material of cefepime dihydrochloride.