Preparation and standardization of 0.1 N Ammonium Thiocyanate USP Volumetric Solution
1. PREPARATION :
Dissolve about 8 g of Ammonium Thiocyanate in 1000 ml of water.
2. STANDARDISATION :
Accurately measure about 30 ml of 0.1 N Silver Nitrate VS into a glass-stoppered flask. Dilute with 50 ml of water, then add 2 ml of Nitric acid and 2 ml of Ferric Ammonium Sulfate TS, and titrate with the Ammonium Thiocyanate solution to the first appearance of a red-brown colour.
Calculation :
Normality (N) = [Volume of AgNO3 (in ml) x Normality of AgNO3] / [ Titration Reading (in ml)]
Limit : 0.1 N ± 5 % (0.0950 N – 0.1050 N)
3. PREPARATION OF INDICATORS / REAGENTS :
a. Ferric Ammonium Sulfate TS:
Dissolve 8 g of Ferric Ammonium Sulfate in water to make 100 ml.
b. 0.1 N Silver Nitrate VS:
Preparation and standardization as per Doc. Ref. No.: D/VS/USP/002
4. STORAGE CONDITION :
Store in glass-stoppered bottles.