Determination of Moxifloxacin in Human Plasma by UPLC-MS/MS and its Application to a Pharmacokinetic Study

A rapid, sensitive and selective ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of moxifloxacin (MFX) in human plasma. Sample preparation was accomplished through a simple one-step deproteinization procedure with acetonitrile to a 0.1 mL plasma sample. Plasma samples were separated by UPLC on an Acquity UPLC BEH C18 column using a mobile phase consisting of acetonitrile- 0.1% formic acid in water with gradient elution. The total run time was 2.0 min and the elution of MFX was at 1.08 min. The detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction-monitoring (MRM) mode using the respective transitions m/z 402.3 -> 384.3 for MFX and m/z 237.1 -> 194.2 for carbamazepine (internal standard), respectively. The calibration curve was linear over the range of 2.5-5000 ng/mL with a lower limit of quantitation (LLOQ) of 2.5 ng/mL. Mean recovery of MFX in plasma was in the range of 79.4-87.1%. Intra-day and inter-day precision were in the range of 91.7-108.2%. This method was successfully applied in pharmacokinetic study after oral administration of 400 mg MFX in healthy Chinese volunteers.