Levofloxacin Carboxylic Acid (Levofloxacin Difluoro Impurity)

(3S)-9,10-Difluoro-2,3-dihydro-3-methyl-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylic Acid; Levofloxacin Q-Acid; USP Levofloxacin Related Compound B;|(S)-9,10-Difluro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid ;