Resistance of Bacteria and Embryonic Tissue to Germicidal Substances. VI. Iodine Trichloride

Abstract

Iodine trichloride (ICl3) was first introduced as a germicide by von Langenbach. It was described as a powerful disinfectant and recommended for the sterilization of hands, instruments and other surgical uses. According to Hailer the chemical is stable in concentrated solutions. In less concentrated solutions the iodine trichloride decomposes into iodine mono-chloride, iodic acid and hydrochloric acid, according to the equation, 2 ICl3 + 3 H2O → HIO3 + ICl + 5 HCl. In more dilute solutions the iodine monochloride decomposes to form iodic acid, free iodine and hydrochloric acid, 10 ICl + 6 H2O → 2 HIO3 + 8 I + 10 HCl. The effectiveness of the compound is due probably to the amount of free iodine liberated. In the first paper of this series methods were described for comparing the resistance of bacteria and embryonic chick heart tissue to germicidal compounds. A Staphylococcus aureus phenol coefficient and a toxicity index were determined for each germicide tested. The highest dilution of phenol required to kill Staphylococcus aureus in 10 minutes but not in 5 minutes was 1:65. For iodine trichloride it was 1:6,000. This gave iodine trichloride a Staphylococcus aureus phenol coefficient of 92 by the method of Reddish. Rideal and Rideal reported that a concentration of 50 parts per million was required to destroy typhoid bacilli in 30 minutes. A saturated aqueous solution showed a phenol coefficient of 94. The activity of the compound was found to be only slightly impaired by the addition of albumin or salts. Behring stated that iodine trichloride was a powerful disinfectant. He found that a 0.1% solution killed vegetative cells in one minute and a 1% solution destroyed spores within a few minutes.