Photometric redox determination of iodate ions in bottled drinking water

Abstract

A photometric procedure is proposed for the highly selective determination of iodate ions in bottled natural drinking water treated with ozone. The procedure is based on the oxidation of Methylene Blue or Variamine Blue by iodate ions. The detection limits for iodates obtained with these reagents are 0.2 and 0.4 μg/L, respectively. In determining iodate ions with Methylene Blue, the permissible weight ratios of related ion are 1: 60 for BrO3− and NO2−; 1: 100 for ClO− and ClO2−; and 1: 200 for ClO3−, ClO4−, IO4−, I−, and Br−. In the case of Variamine Blue, the ratios of related ion are 1: 10 for BrO3− and NO2−; 1: 20 for ClO− and ClO2−; and 1: 100 for ClO3−, ClO4−, IO4−, I−, and Br−. In the concentration range of iodates of 1–10 μg/L, the total error of determination is 5–7%.