利用LC-MS/MS法快速鉴定盐酸头孢吡肟中的同分异构体杂质

目的建立应用LC-MS/MS技术快速鉴定盐酸头孢吡肟原料药中的同分异构体杂质的方法。方法以乙腈-10 mmol·L^-1乙酸铵(5∶95)为流动相经C₁₈柱分离,通过电喷雾串联质谱在线检测，获得相关的色谱和质谱信息。结果在所建立的条件下，盐酸头孢吡肟及其同分异构体杂质获得有效分离，主成分和其同分异构体杂质的保留时间分别为15.28 min和9.18 min，同时它们的二级质谱产物离子信息及其裂解方式呈现明显的差异。结论本法能快速、准确地分离鉴定盐酸头孢吡肟原料药中的同分异构体杂质，从而可以对其原料药进行质量控制。

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

AIM: 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. CONCLUSION: 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.