Simultaneous determination of metronidazole and spiramycin I in human plasma, saliva and gingival crevicular fluid by LC-MS/MS.

An analytical validation of a new liquid chromatographic-mass spectrometric (LC-MS/MS) method for simultaneous determination of metronidazole and spiramycin I concentrations in human plasma, saliva and gingival crevicular fluid (GCF) is presented. Ornidazole was used as an internal standard, and sample pre-treatment consisted of a liquid-liquid extraction. Chromatographic separation was achieved on a 5 microm Kromasil C18 column (150 mm x 4.