Isolation and identification of a new impurity in mitoxantrone hydrochloride

An unknown impurity in mitoxantrone hydrochloride bulk drug was detected by HPLC at levels around 0.5%. This impurity was isolated from a sample of crude mitoxantrone using preparative HPLC and was characterized as 1,4-dihydroxy-5-2-2-hydroxyethyl-amino-ethyl-amino-8-2-bis 2-hydroxyethyl-amino-ethyl-amino-9,10-anthracenedione based on its spectral data (NMR, IR and MS). The origin and structural elucidation of this impurity are discussed in the paper.