0.05 M EDTA Solution Preparation and Standardization
0.05 M EDTA Solution Preparation:
For 0.05 M EDTA Solution Preparation firstly Weigh accurately about 18.60 gm of disodium edetate and transfer to a 1000mL (1 Liter) grade A volumetric flask. Dissolve disodium edetate in sufficient purified water and makeup the volume with purified water.
EDTA full form is Edathamil; Ethylenediaminetetraacetic Acid; [Ethylenedinitrilo]tetraacetic Acid (C10H16N2O8 ).
EDTA is well knownmedication used in toxicity management & treatment due to heavy metal.
Standardization of 0.05 M EDTA
Method 1:
Weigh precisely about 0.10 g of calcium carbonate (CaCO3) and transfer to a conical flask.
Dissolve in 3.0 mL of dilute hydrochloric acid (10 %v/v HCl) and 10.0 mL of purified water.
Boil for solution for about 10 minutes. Then cool it & dilute to 50.0 mL with purified water (CO2 free).
Add few drops of Erichrom Black T indicator by means of the dropper and Titrate the solution with 0.05 M disodium edetate (EDTA) till endpoint.
Record the volume of disodium edetate solution used during titration.
Same procedure shall be repeated for two more times.
Calculate the molarity of the solution by below-given formula.
Here,
W = Weight of calcium carbonate (in gm).
V = Consumed Volume of disodium edetate solution (in mL).
Method 2:
Weigh precisely about 0.40 gm granulated zinc (Zn), dissolve by moderate warming in 12 mL of dilute hydrochloric acid (HCl) and 0.05 mL of bromine water.
Boil to remove excess bromine, cool and sufficient water to produce 200.0 mL.
Pipette 20.0 mL of the resultant solution into a volumetric flask and nearly neutralize with 2M sodium hydroxide (2M NaOH).
Dilute to about 150.0 mL with purified water, add adequate qty. of ammonia buffer pH 10.0 to dissolve the precipitate and add 5.0 mL in extra.
Add 50.0 mg of mordant black-II mixture and titrate with the disodium edentate solution until the solution truns green.
Calculation:
Each ml of 0.05M disodium edetate is equivalent to 0.00327g of Zn.
Determine the molarity in triplicate (3 Times) and calculate the average value (Result Variation should not be more than 0.2%.)
Standardized frequently: Every 15 days.
Validity & Precaution of EDTA Solution:
30 Days from the date of preparation and ideally Re-Standardization after15 days and when required.
Precaution: Check before use of the solution for the physical appearance (Mainly change in color), fungal growth and sedimentation.
Preparation of 0.1 M edetate disodium
Dissolve 37.22 gm of disodium EDTA in purified water to make 1000 mL
Preparation of 0.01 M EDTA
Transfer 100 mL of 0.1 M edetate disodium to a 1000 mL volumetric flask. Dilute with purified water to volume.
Standardization of 0.01 M Edetate Disodium as per USP:
Accurately weigh about 40.0 mg of secondary standard calcium carbonate, previously dried at 110°C for 2 hr in a oven and cooled in a desiccator, or dried according to the label instructions, transfer to a 400 mL beaker.
Protection the beaker with a watch glass, and add 4.0 mL of diluted hydrochloric acid (HCl- 10%v/v) from a pipet inserted between the lip of the beaker and the edge of the watch glass.
Wash down the sides of the beaker, the outer surface of the pipet, and the watch glass with water, and dilute with purified water to about 200 mL.
While stirring the solution, preferably with a magnetic stirrer, add about 30.0 mL of the edetate disodium (EDTA) solution from a 50.0 mL burette.
Adjust the solution with sodium hydroxide (NaOH) to a pH of 12.0 to 13.0, add 300 mg of hydroxy naphthol blue, and continue the titration with edetate disodium (EDTA) solution to a blue endpoint.