Selective photometric redox determination of periodate and iodate ions in bottled drinking water

Abstract

method has been developed for the selective photometric redox determination of periodate and iodate ions in bottled drinking water based on redox reactions of analytes with Methylene Blue with different duration of processes, products of which form the analytical signal. The limits of detection for periodate and iodate ions are 0.5 and 0.2 µg/L, respectively. The allowable weight ratios for concomitant ions for (at the analyte concentration 2 µg/L) are as follows: I^–, Br^–, IO₃ ^–, BrO₃ ^–, ClO^–, CIO^–, CIO₂ ^–, CIO₃ ^– and CIO₄ ^–(1: 100); and for IO₃ ^– (1 µg/L) are: BrO₃ ^– ₂ ^–, NO (1: 60), CIO^–, CIO₂ ^–, (1: 100), and I^–, Br^–, IO₄ ^–, CIO₃ ^–, and CIO₄ ^– (1: 200). The HCIO₃ ^–, Cl^–, and SO₄ ^2- anions and Ca²⁺, Mg²⁺, Na⁺, K²⁺, and NH₄ ⁺ cations are macrocomponents of drinking water and at total concentrations up to 10 g/L do not affect the results of analysis. In the concentration range 1–10 µg/L of IO₄ ^– andIO₃ ^–, the total error of determination is 5–7%.