Ondansetron EP Impurity B Catalogue A264582 M.W 598.74 M.F C37H38N6O2 Specifications FAQs 6,6′-Methylene-bis[(3RS)-9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-1,2,3,9-tetrahydro-4H-carbazol-4-one