Clinical Research Associates

Test Method for Percent H₂O₂ in Bleaching Gel

Aug 16, 2000
Clinical Science Department
Clinical Research Associates

The percent H₂O₂ in bleaching gel was determined using the USP 24 monograph for Hydrogen Peroxide Concentrate (p. 863). The following is a summary of the test method.

Approximately 0.1 g of bleach gel is weighed into a beaker using an analytical balance accurate to 0.1 mg. 20 ml of deionized water is added to the beaker, & the contents stirred until homogenous. 20 ml of 2 N sulfuric acid is added & stirred until homogenous.

Potassium permanganate 0.1 N is used as the titrant for the acidified gel solution. The titrant is added to the solution while the solution is being constantly stirred. The solution starts clear, but as the titrant is added it briefly turns bright purple, then becomes clear again. The titration is complete when a faint pink color is sustained in the solution.

The basic equation for calculating percent H₂O₂ is as follows:

% H₂O₂=	[hydrogen peroxide conversion factor (1.701)][titrant used (ml)][normality of titrant (0.1)] [mass of gel (g)]

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