Linagliptin Dimer Impurity

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