FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY OF THE ORGANOMETALLIC PARASITICIDE, MEGLUMINE ANTIMONATE

The mass spectrometry of an organometallic parasiticide used for treatment of leishmaniasis was studied using primarily fast-atom bombardment with complementary studies conducted using electrospray ionization. The positive-ion mass spectrum of meglumine antimonate contained ions with characteristic antimony isotope ratios (57:43) at m/z 627/629, 507/509, 406/408 and 314/316. There was also evidence of ion clusters containing antimony atoms (Sb-1-3), which decompose to the mass 507/509 species under acid pH conditions. For meglumine antimonate, an empirical formula C14H30O10N2Sb (molecular weight 507) is proposed with a structure containing four Sb-O bonds in a symmetrical geometry.