Levofloxacin-13C,d3,(S)-9-fluoro-3-methyl-7-oxo-10-(piperazin-1-yl)-3,7-dihydro-2H-[1,4]oxazino[2,3,4- ij]quinoline-6-carboxylic acid-13C-D3,"Labeled Levofloxacin, intended for use as an internal standard for the quantification of Levofloxacin by GC- or LC-mass spectrometry.",Levofloxacin Stable Isotopes