Determination of Moxifloxacin in Patients Plasma by LC-MS/MS

OBJECTIVE To develop an LC-MS/MS method for determination of moxifloxacin in patients plasma and applied to drug monitoring. METHODS The plasma samples were precipitated with acetonitrile, with pregabalin as an internal standard. The separation was achieved on ZORBAX SB C₁₈column (2.1 mm×100 mm, 3.5 μm) and eluted with linear gradient using acetonitrile and water (both contain 0.1% formic acid) at the flow rate of 0.30 mL·min^-1, the injection volume was 10 μL and the column temperature was 30℃. The total time of the analysis was 4.0 min. Detection of the analytes were achieved using positive ion electrospray ionization (ESI) in the multiple reaction monitoring (MRM) mode. RESULTS The linear calibration curve of moxifloxacin obtained concentration range of 10-5 000 ng·mL^-1(r=0.997 8), with the lower limit of quantitation (LLOQ) of 10 ng·mL^-1. The accuracy of quality control sample was 94.2%-107.1%. Intra-day and inter-day relative standard deviations were both <15%. The extraction recovery of low, middle and high concentrations was 82.4%-89.8%, respectively. CONCLUSION The established method is rapid, sensitive, accurate, specific and reliable, and it is suitable for the study of therapeutic drug monitoring of moxifloxacin.