Analysis of flumequine enantiomers in rat plasma by UFLC-ESI-MS/MS

In this study the analysis and confirmation of flumequine enantiomers in rat plasma by ultra-fast liquid chromatography coupled with electron spray ionization mass spectrometry (using propranolol as an internal standard [IS]) was developed and validated. Plasma samples were prepared by liquid-liquid extraction using methyl tert-butyl ether as the extraction solvent. Direct resolution of the R- and S-isomers was performed on a CHIRALCEL OJ-RH column (4.6x150mm, 5m) using acetonitrile / 0.1% formic acid / 1mM ammonium acetate as the mobile phase. Detection was operated by electron spray ionization in the selected ion monitoring and positive ion mode. The target ions at m/z 262.1 and m/z 260.1 were selected for the quantification of the enantiomers and IS, respectively. The linear range was 0.5-500ng/mL. The precisions (coefficient of variation, CV%) and recoveries were 1.43-8.68 and 94.24-106.76%, respectively. The lowest quantitation limit for both enantiomers is 0.5ng/mL, which is sensitive enough to be applied to sample analysis in other related studies.