HPLC method for the simultaneous analysis of fluoroquinolones and oxazolidinones in plasma

A chromatographic method was implemented and validated for the simultaneous determination of antimicrobials proposed for the treatment of mycetoma: three fluoroquinolones: ciprofloxacin, moxifloxacin and sparfloxacin; two oxazolidinones: DA-7157 (DA2; torezolid) and its prodrug DA-7218 (DA1). Separation of analytes was achieved on an Atlantis dC18 column (150 × 4.6 mm i.d., 5 µm particle size) with a mobile phase composed of acetonitrile and trifluoroacetic acid 0.1% (v/v) using a gradient program. Total running time was 30 min. Quantification of sparfloxacin was carried out using a DAD at 278 nm; the oxazolidinones DA1 and DA2 and the quinolones ciprofloxacin and moxifloxacin were analyzed by fluorescence with an excitation wavelength of 292 nm and an emission wavelength of 525 nm. Intraday precision was in the range of 3.2 and 14.1%. Linearity range was from 0.3 to 10 µg/mL for sparfloxacin using DAD detector, and from 0.2 to 10 µg/mL for ciprofloxacin, 0.3 to 10 µg/mL for DA2, 0.4 to 10 µg/mL for DA1 and 0.04 to 10 µg/mL for moxifloxacin with fluorescence detector. Acetonitrile was used to precipitate proteins from plasma. Recoveries at low, medium and high concentration were between 80 and 120%. Limits of quantification were between 0.04 and 0.4 µg/mL in plasma. The method can be applied for individual or simultaneous determination of the antimicrobials in plasma.