New Methods for the Colorimetric Determination of Halogen Residuals. Part I. Iodine, Iodide, and Iodate

This article discusses a rapid, sensitive, and accurate colorimetric method that has been developed for the determination of iodine residuals in water in the presence of free and combined chlorine. The article also discusses a colorimetric method for the determination of iodide ion (I‐) residuals that has been developed using potassium peroxymonosulfate, KHS05, first to oxidize the iodide ion to iodine. Similarly, the iodate ion (I03‐), may be determined colorimetrically by the controlled addition of iodide ions and acid and the resulting production of elemental I2. The reaction is stoichiometric and the concentration of iodate ion may be related to the iodine liberated.