m-Iodobenzylguanidine hemisulfate  (MIBGHS) is a precursor for radioiodine-labeled m-iodobenzylguanidine (MIBG), which is used as a radio-imaging and therapy agent for neuroendocrine tumours and myocardial sympathetic nerve activity. The purity of the precursor, source of impurity, and derivatives must all be calculated in order to ensure the medicine’s consistency and...