Quinacrine mustard hydrochloride is a fluorescent dye and polycyclic aromatic agent that acts as a mutagen to induce mutants in bacteria.Quinacrine mustard hydrochloride selectively binds to adenine-thymine (AT) base pairs, but not to guanine-cytosine (GC). Quinacrine mustard (hydrochloride) selectively binds to adenine-thymine (AT) base pairs rather than to guanine-cytosine (GC) base pairs, inducing cell cycle arrest at G2/M. Quinacrine mustard (hydrochloride) has been used to label chromosomes for karyotyping by autoradiography.