Doxorubicin Impurity 3 Catalogue D335733 CAS 58199-98-7 M.W 400.34 M.F C20H16O9 Specifications FAQs (2S,4S)-2,4,5,12-tetrahydroxy-7-methoxy-6,11-dioxo-1,2,3,4,6,11- hexahydrotetracene-2-carboxylic acid