Determination of Gatifloxacin in Human Urine by Liquid Chromatography-Tandem Mass Spectrometry

Abstract

Gatifloxacin (GTF) is an antibiotic of the fourth-generation fluoroquinolone family that inhibits the bacterial enzymes DNA gyrase and topoisomerase IV. A reliable, sensitive and selective isocratic reversed phase liquid chromatographic-tandem mass spectrometric (LC-MS-MS) method was developed to determine gatifloxacin (GTF) in human urine. GTF, in urine after solid-phase extraction with SPE cartridge, was analyzed on a C₁₈ column (Symmetric 3.5 µm; 75×4.6 mm i.d) interfaced with a triple quadrupole tandem mass spectrometer. Positive electrospray ionization was employed as the ionization source. The mobile phase consisted of 5 mM ammonium formate (pH 2.9):acetonitrile (20:80, v/v). A linear relationship was obtained over a concentration range of 10–1000 ng mL^-1 GTF with the lower limit of quantitation value of 10 ng mL^-1. The intra-day and inter-day relative standard deviation across three validation runs over the entire concentration range was <11.1%. The accuracy determined at three different concentrations of GTF (25.0, 500.0 and 850.0 ng mL^-1) was within 1%.

Keywords: Gatifloxacin, quantification, liquid chromatography-tandem mass spectrometry