What are the possible interferences with the Hydrogen Peroxide Test Kit, Model HYP-1?

Document ID

Document ID TE6050

Version

Version 2.0

Status

Status Published

Published Date

Published Date 10/18/2018
Question
What are the possible interferences with the Hydrogen Peroxide Test Kit, Model HYP-1?
Summary
Interferences with the Hydrogen peroxide test kit
Answer
Hydrogen Peroxide Test Kit, HYP-1 (Product # 2291700). Hydrogen peroxide is a very weak acid. It is a good oxidizing agent in both acidic and basic solutions. For example, Hydrogen peroxide oxidizes Fe2+ and Mn2+ in acidic and basic solutions. It can also act as a reducing agent for some ions like chlorine in acidic and basic solutions.

Some possible interferences:

Sulfites will give a green color. This test also suffers from interference from other oxidants and transition metals (Fe, Cu, Ni, Cr).

When a blue color is developed it is related to the reduction of molybdate, which is added as a catalyst. The chemistry is based on generation of free iodine, which is titrated vs. thiosulfate. Problems may arise in a complicated matrix such as wastewater.

This test is not specific to Hydrogen peroxide in complicated matrices. Because it is a generic redox titration, it will pick up other oxidants. So, if the sample has chlorine, ozone, etc, this test will pick it up and read it as Hydrogen peroxide.

Method information:
The first reagent is the ammonium molybdate solution. It consists of molybdate and sulfuric acid. The molybdate is a catalyst for the reaction, and the acid brings the pH down, which is optimal for the test. Then the Sulfite 1 reagent is added. This reagent contains potassium iodide and starch (starch/iodine redox titration.) The hydrogen peroxide oxidizes the iodide to iodine. Iodine in the presence of starch is an inky blue/black color. The solution is then titrated with sodium thiosulfate. This reduces the iodine back to iodide.
Iodide with starch produces no color, so when the blue color goes away, the titration is done.

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