Detemination of Cefixime in Human Plasma by HPLC-MS/MS

To establish a high performance liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for determination cefixime in human plasma. Plasma sample, precipitated using acetonitrile, was separated on a Ultimate XB-CN (5um，2.1×100 mm) column with metronidazole as internal standard. The mobile phase consisted of water-acetonitrile(30:50,V/V), and was at a flow rate of 0.3 mL•min^－1. MS/MS detection in multiple reactions monitoring (MRM) mode using positive electrospray ionization as the ionization source was applied to determine positive ions at m/z 454.2→285.2 for cefixime and m/z 172.2→128.1 for metronidazole. The method was linear in the concentration rang of 0.117-6.231 mg•L^－1(r＝0.995 9), the lower limit of quantification was 117 μg•L^－1, absolute recovery of cefixime was more than 85%, the RSD values of intra-day and inter-day were less than 9.9%. This method is sensitive, specific and suitable for the determination of cefixime in human plasma.