Title: Determination of Peroxide Value
1. Objective: To determine the Peroxide Value of the sample.
- Principle: The peroxide value is the number of mill equivalents of active oxygen that expresses the amount of peroxide contained in 1000 g of the substance.
3. Procedure:
Unless otherwise specified in the individual monograph, weigh accurately 5 g of the substance being examined, into a 250 ml glass-stoppered conical flask, add 30 ml of a mixture of 3 volumes of Glacial Acetic acid and 2 volumes of Chloroform, swirl until dissolved and add 0.5 ml of saturated Potassium Iodide solution. Allow to stand for exactly 1 minute, with occasional shaking, add 30 ml of water and titrate gradually, with continuous and vigorous shaking, with 0.01M Sodium Thiosulphate until the yellow colour almost disappears. Add 0.5 ml of Starch solution and continue the titration, shaking vigorously until the blue colour just disappears (a ml). Repeat the blank titration omitting the substance being examined (b ml). The volume of 0.01 M Sodium Thiosulphate in the blank determination must not exceed 0.1 ml.
Calculate the peroxide value from the expression
Peroxide value = 10 x (a-b)
w
Where, w = weight, in g, of the substance.