Preparation and Standardization of 0.1M Disodium Edetate VS

Preparation and Standardization of 0.1M Disodium Edetate VS:

Reagent Used:

  1. Sodium Hydroxide TS: Dissolve 4.0 g of sodium hydroxide in water to make 100 ml.
  2. Dilute Hydrochloric Acid: Prepare by mixing 22.6 ml of hydrochloric acid with sufficient water to make 100 ml.

Preparation of 0.1M Disodium Edetate:

Dissolve 37.22 gm of Disodium edetate in water to make 1000 ml.

For lower strength follow as given in the below table:

Quantity of Disodium edetate
to be taken (in g)
Makeup with Water
(in ml)
Strength of VS
18.610000.05 M
7.510000.02 M
3.7510000.01 M
Lower Concentration Solution Preparation

Standardization of 0.1M Disodium Edetate VS (Manual):

Dissolve 400mg of chelometric standard Calcium carbonate previously dried at 210°C for 4 hours and cooled in a desiccator, transfer to a 400 ml beaker, add 10 ml of water and swirl to form a slurry. Cover the beaker with a watch glass, and introduce 4 ml of hydrochloric acid from a pipet inserted between the lip of the beaker and the edge of the watch glass.

Swirl the contents of the beaker to dissolve the calcium carbonate. Wash down the sides of the beaker, the outer surface of the pipette, and the watch glass with water, and dilute with water to about 100ml. While stirring the solution, preferably with a magnetic stirrer, add about 30ml of the Disodium edetate solution from a 50ml burette.

Adjust the solution to a pH of 12-13 with sodium hydroxide TS and 300mg of Hydroxyl naphthol blue and continue the titration with the Disodium edetate solution to a blue endpoint.

Standardization of 0.1M Disodium Edetate VS (Potentiometrically):

Weigh accurately about 100mg of chelometric standard calcium carbonate, previously dried according to the label instructions or, if this information is not available, at 210°C for 4 hours, transfer to the 400ml beaker, add 10ml of water, and swirl to form a slurry. Cover the beaker with a watch glass, and introduce 1 ml of diluted hydrochloric acid from a pipet inserted between the lip of the beaker and the edge of the watch glass.

Swirl the contents of the beaker to dissolve the calcium carbonate. After dissolution, wash the sides of the beaker, the outer surface of the pipette, and the watch glass with water, and dilute with water to about 100ml. While stirring the solution, preferably with a magnetic stirrer, add about 30ml of the Disodium edetate solution from a 50ml burette.

Adjust the solution to a pH of 12-13 with sodium hydroxide TS and titrate potentiometrically with the edetate disodium solution using a combined calcium ion-selective electrode.

Calculation Formula for 0.1M Disodium Edetate VS:

Molarity of Disodium Edetate VS = Wx (Assay /100)/100.09xV

where,

V= Volume of Disodium Edetate consumed in ml

W= Weight of Calcium carbonate taken in mg.

Preparation and Standardization of 0.1M Disodium Edetate VS
Preparation and Standardization of 0.1M Disodium Edetate VS

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Preparation and Standardization of 0.1M Disodium Edetate VS