Preparation and standardization of 0.1 M Zinc Sulphate EP Volumetric Solution

1.  PREPARATION:

Accurately weigh and dissolve 29.0 g of Zinc sulphate in sufficient water to produce 1000 ml.

2. STANDARDISATION:

To 20 ml of Zinc sulphate VS add 5 ml of dilute 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 in excess. Titrate with 0.1 M Disodium edetate until the violet-pink colour changes to yellow.

1 ml of 0.1 M Disodium edetate is equivalent to 6.54 mg of Zn.

Calculation:

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. Dilute Acetic acid:

Dilute 12 g 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/EP/001

c. Xylenol orange triturate:

Triturate 1 mg of Xylenol orange with 99 mg of Potassium nitrate.

Test for sensitivity: To 50 ml of water add 1 ml of dilute Acetic acid, 50 mg of Xylenol orange triturate and 0.05 ml of Lead nitrate solution. Add Hexamethylenetetramine until the colour changes from yellow to violet-red. After addition of 0.1 ml of 0.1 M Disodium edetate the colour changes to yellow.

d. Lead nitrate solution:

A 33 g/l solution of Lead nitrate.

4. STORAGE CONDITION:

Store in glass stoppered bottles.