TESTS
PURITY TESTS
Peroxide value
Weigh accurately 5 g of the sample into a 200-ml conical flask. Add 30 ml of a 2:3 solution of chloroform and acetic acid TS and close the flask with a stopper. Heat with warm water and swirl to dissolve the sample. Cool to room temperature and add 0.5 ml of saturated potassium iodide solution. Close the flask with the stopper and shake vigorously for 60±5 sec. Add 30 ml of water and titrate immediately with 0.01 N sodium thiosulfate using starch TS as indicator. Carry out a blank determination.
Peroxide value = (a-b) x N x 1000/W
where
a = volume (ml) of sodium thiosulfate used for the sample
b = volume (ml) of sodium thiosulfate used for the blank
N = normality of the sodium thiosulfate
W = weight of sample (g)