The ESI-MS spectrum of an authentic sample of heme isolated from human Hb (the signal at m/z 616 is due to a heme radical cation). (b) The spectrum of a putative heme-nitrosodinitrotoluene adduct generated by incubation of Hb with TNT in the presence of sodium hydrosulfite under anaerobic conditions (tube 1, see
Experimental for details). This putative heme adduct is acid labile and undergoes exclusive release of the heme moiety at or below pH - 5. (c) The CID spectrum of m/z
827 yielding exclusive loss of 2 11 Da.