Electromigration of Iodobismuthite in Colloidal Systems

Abstract

Electromigration of the complex ion (BiI₅) of sodium iodobismuthite (Na₂BiI₅) in colloidal systems is of interest in connection with the absorption and cerebrospinal penetration of this electronegative bismuth in antisyphilitic medication. 1 The red (BiI₅) ion migrates to the anode in aqueous, alcoholic and glycolic media. 2 The question of cerebral and spinal fluid penetration hinges, partly at least, on another question, whether the unchanged complex ion (BiI₅) can migrate in colloidal systems analogous to those of the body, such as serum and a gel. Direct test of migratibility in living tissue and blood is practically impossible. Therefore, a special electrolytic cell, which also acted as a model, containing serum, agargel, and iodobismuthite was used.

The anionic character of the bismuth in iodobismuthite was originally demonstrated with bare platinum electrodes. 2 However, such electrodes require constant attention in order to avoid decomposition of the labile complex (BiI₅) ion. Therefore, the use of KCl-agar bridges in the anode and cathode chambers was suggested, since their use would prevent loss of the electrical charge on, and consequent decomposition of, the complex (BiI₅) ion. This arrangement also made it practically feasible to test the migration, if any, of the (BiI₅) ion in colloidal systems, i. e., into serum and from serum into the agar-gel. The analogy to conditions prevailing in the intramuscular administration of iodobismuthite (iodobismitol) was almost perfect. That is, in the model, the serum phase corresponded to the lymph and plasma (blood) with which iodobismuthite comes in contact when injected intramuscularly, and the agar-gel phase, to the tissues and brain to be penetrated. Such an electrical field does not exist, of course, in the living fluids and tissues.