Methods
Hydrogen peroxide is a strong oxidizing agent with a variety of uses. Applications include the treating of industrial effluents and domestic waste and serving as a disinfectant in aseptic packaging.
For the food and beverage industry, CHEMetrics Hydrogen Peroxide CHEMets® and Vacu-vials® products are used extensively to monitor sterilization solutions in the packaging and sanitizing processes.
The Ferric Thiocyanate Method
Reference: D. F. Boltz and J. A. Howell, eds., Colorimetric Determination of Nonmetals, 2nd. ed., Vol. 8, p. 304 (1978).
The ferric thiocyanate method consists of ammonium thiocyanate and ferrous iron in acid solution. Hydrogen peroxide oxidizes ferrous iron to the ferric state, resulting in the formation of a red thiocyanate complex. Chlorine will not interfere with this method. Ferric iron will interfere. Results are expressed as ppm (mg/L) H2O2.
The DPD Method
References: USEPA Methods for Chemical Analysis of Waters and Wastes, Method 330.5 (1983). APHA Standard Methods, 21st ed., Method 4500-Cl G (2005). D.F. Boltz and J.A. Howell, eds., Colorimetric Determination of Nonmetals 2nd ed., Vol. 8, p. 303 (1978).
With the DPD Method, hydrogen peroxide reacts with DPD (N, N-diethyl-p-phenylenediamine) in the presence of potassium iodide and ammonium molybdate to form a pink color. Results are expressed as ppm (mg/L) H2O2.
The Ceric Sulfate Titrimetric Method
Reference: Developed by CHEMetrics, Inc.
CHEMetrics developed a titrimetric method using ceric sulfate as the titrant and ferroin as the end point indicator. A color change from green to orange signals the end of the titration. Results are expressed as percent (%) H2O2.
The Ceric Sulfate Go-No-Go Method
Reference: Developed by CHEMetrics, Inc.
Developed for clinical applications where hydrogen peroxide in sterilizing/disinfecting solutions with a MEC (minimum effective concentration) of 6.0 + 1.0% must be monitored for efficacy. A single, small dose of sample is added to a screw cap vial containing ceric sulfate and he endpoint indicator ferroin.
An immediate color change occurs to signal that the hydrogen peroxide level in the sample is either above or below 6.0%.