Abstract

Purpose: To establish a novel method for the determination of gatifloxacin (GAFX) by Eu^3+-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 Eu^3+-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