Disodium Edetate VS

Sodium edetate; C₁₀H₁₄N₂Na₂O₈,2H₂O = 372.2

For a 0.1m solution Dissolve 37.5 g of sodium edetate in 500 mL of water, add 100 mL of 1 M sodium hydroxide and dilute to 1000.0 mL with water.

Standardisation. Dissolve 0.120 g of zinc in 4 mL of hydrochloric acid. Add dilute sodium hydroxide solution until the solution is weakly acid and carry out the assay of zinc by complexometry (2.5.11).

1 mL of 0.1 M sodium edetate is equivalent to 6.538 mg of Zn.

Storage In a polyethylene container.

For a 0.05m solution Dissolve 18.6 g of disodium edetate in sufficient water to produce 1000 mL.

Ascertain its exact concentration as described below. Each mL of 0.05m disodium edetate VS is equivalent to 3.269 mg of Zn.

For a 0.02m solution Dissolve 7.444 g of disodium edetate in sufficient water to produce 1000 mL.

Ascertain its exact concentration in the following manner. Dissolve 0.100 g of zinc, in granules, in 4 mL of 7m hydrochloric acid and add 0.1 mL of bromine water. Boil to remove excess bromine, cool and dilute to 100 mL with water. Dilute 25 mL of this solution to 200 mL with water, add about 50 mg of xylenol orange triturate and hexamine until the solution becomes violet-pink and add 2 g of hexamine in excess. Titrate with the disodium edetate solution until the violet-pink colour changes to yellow. Each mL of 0.02m disodium edetate VS is equivalent to 1.308 mg of Zn.

For a 0.01m solution Dissolve 3.722 g of disodium edetate in sufficient water to produce 1000 mL.

Ascertain its exact concentration as described above but dilute 10 mL, in place of 25 mL, of this solution to 200 mL with water. Each mL of 0.01m disodium edetate VS is equivalent to 0.6538 mg of Zn.