Determination of gatifloxacin in injection solutions and urine by europium-sensitized chemiluminescence

Purpose: To establish a novel method for the determination of gatifloxacin (GAFX) by Eu3+-sensitized chemiluminescence (CL). Methods: The experimental conditions including sample volume, flow rate, sensitizers, inorganic acids, sodium thiosulfate concentration and Ce4+ concentration were investigated and optimized. The interferences were examined. The results obtained by this method were compared with UV spectrometry. The fluorescence emission spectra of GAFX and Eu3+-GAFX systems were compared with the CL spectra of Ce4+-Na2S2O4-Eu3+-GAFX systems. Results: The CL intensity was linearly related to the concentration of GAFX over the range 1.0×10-8–8.0×10-6 g/ml. The detection limit (3σ) is 3×10-9 g/ml and the relative standard deviation is 2.0%. The method was applied to the analysis of GAFX in injection solutions and human urine samples with a recovery of 99%–105%. Conclusions: The possible mechanism of the CL reaction may involve an intermolecular energy transfer which takes place from the excited intermediate product SO2* to the ligand (GAFX) in the chelate (Eu3+-GAFX), and then through intramolecular energy transfer from Eu3+-GAFX* to Eu3+*-GAFX, followed by the narrow characteristic emission of Eu3+*. The proposed Eu3+-sensitized CL system has good linearity, higher sensitivity and precision and is suitable for the analysis of GAFX in injection solutions and biological samples.

Keywords: Flow injection Europium-sensitized chemiluminescence Gatifloxacin Injection Urine