Preparation and standardization of 0.1 M Zinc Sulphate BP Volumetric Solution
Accurately weigh and dissolve 29.0 g of Zinc sulphate in sufficient water to produce 1000 ml.
To 20 ml of Zinc sulphate VS add 5 ml of 2 M Acetic acid. Introduce this solution into 500 ml conical flask and dilute to 200 ml with water. Add about 50 mg of Xylenol orange triturate and Hexamethylenetetramine until the solution becomes violet- pink. Add 2 g of Hexamethylenetetramine in excess. Titrate with 0.1 M Disodium edetate until the violet-pink colour changes to yellow.
Each ml of 0.1 M Disodium edetate is equivalent to 0.02875 g of ZnSO4, 7H2O.
Molarity (M) = [Titration reading (ml) x Exact Molarity of 0.1 M Disodium edetate]/ 20
Limit: 0.1 M ± 5 % (0.0950 M – 0.1050 M)
3. PREPARATION OF INDICATORS / REAGENTS:
a. 2 M Acetic acid:
Dilute 11.4 ml of Glacial Acetic acid to 100 ml with water.
b. 0.1 M Disodium edetate:
Preparation and standardization as per Doc. Ref. No. D/VS/BP/007.
c. Xylenol orange triturate:
Triturate 1 mg of Xylenol orange with 99 mg of Potassium nitrate.
It should comply with the following test:
Sensitivity: Add 50 mg to a mixture of 50 ml of water, 1 ml of 2 M Acetic acid and 0.05 ml of Lead nitrate solution. Add sufficient Hexamine to change the colour from yellow to violet-red, and 0.1 ml of 0.1 M Disodium edetate VS. the colour changes to yellow.
d. Lead nitrate solution:
A 3.3 % w/v solution of Lead (II) nitrate.
4. STORAGE CONDITION:
Store in glass-stoppered bottles.