The stability, staining and corrosive properties of an iodine-non-ionic surface-active agent complex

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Abstract
The stability of concentrated and dilute solutions of an iodine-cetomacrogol complex and the staining of fabrics and the corrosion of metals it produced, have been compared at the same available iodine concentration, with a system based on weak iodine solution B.P. The available iodine content of the complex decreased on storage, but this loss was associated with the production of an equivalent amount of hydrogen iodide, such that the total iodine content of the system remained constant. The reaction was accelerated by an increase in temperature, but was neither a photochemical nor an oxidative decomposition. The complex was not subject to the large losses of solvent which occurred with the potassium iodide-ethanol system, and in dilute solution was generally more stable; both systems being more stable in acid conditions. Dilute solutions of electrolytes, as found in hard waters, had little effect on the stability of either type of dilute solution except where they caused the pH to rise, but potassium salts produced a characteristic precipitation of the complex, which resulted in a loss of available iodine. The technique of testing the permanency of staining indicated that the complex often produced the less permanent stain, but it was not completely devoid of staining properties. The complex was less corrosive towards certain metals when tested by a static total immersion test, but when the attack was severe as with aluminium and copper, there was little difference between the two iodine systems in their corrosive action.