title: Development and validation of a fast isocratic liquid chromatography method for the simultaneous determination of norfloxacin, lomefloxacin and ciprofloxacin in human plasma.
abstract: A simple and fast liquid chromatographic method coupled with fluorescence detection (LC-FD) is reported, for the first time, for the simultaneous quantification of norfloxacin (NOR), ciprofloxacin (CIP) and lomefloxacin (LOM) in human plasma, using levofloxacin as internal standard (IS). Sample preparation consists of a single-step precipitation of plasma proteins followed by vortex-mixing and centrifugation. Chromatographic separation was achieved within 7  min on a reversed-phase C(18) column with a mobile phase consisting of 0.1% aqueous formic acid (pH = 3.0, triethylamine)-methanol (82:18, v/v) pumped isocratically at 1.2  mL/min. The detector was set at excitation/emission wavelengths of 278/450  nm. Calibration curves were linear (r(2) ≥ 0.994) in the range of 0.02-5.0 µg/mL, and the limit of quantification was established at 0.02 µg/mL for all analytes (NOR, CIP and LOM). The overall precision did not exceed 8.19% and accuracy was within ±10.91%. NOR, CIP and LOM were extracted from human plasma with an overall mean recovery ranged from 90.1 to 111.5%. No interferences were observed at the retention times of the analytes and IS. This novel LC-FD method enables the reliable determination of NOR, CIP and LOM in a single chromatographic run, which may be suitable to support human pharmacokinetic-based studies with those antimicrobial agents.
authors.affiliation: Faculty of Pharmacy, University of Coimbra, Polo das Ciencias da Saude, Azinhaga de Santa Comba, Coimbra, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Sousa
authors.forename: Gilberto
authors.initials: G
authors.lastname: Alves
authors.forename: Ana
authors.initials: A
authors.lastname: Fortuna
authors.forename: Angelina
authors.initials: A
authors.lastname: Pena
authors.forename: Celeste
authors.initials: C
authors.lastname: Lino
authors.forename: Amílcar
authors.initials: A
authors.lastname: Falcão
mesh_terms: D000890:Anti-Infective Agents / Q000097:blood*; D002853:Chromatography, Liquid / Q000379:methods*; D002939:Ciprofloxacin / Q000097:blood*; D004355:Drug Stability; D024841:Fluoroquinolones / Q000097:blood*; D006801:Humans; D064704:Levofloxacin; D016014:Linear Models; D009643:Norfloxacin / Q000097:blood*; D015242:Ofloxacin / Q000032:analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D002939:Ciprofloxacin; D064704:Levofloxacin; D015242:Ofloxacin; C053091:lomefloxacin; D009643:Norfloxacin