0.02 M Edetate Disodium VS

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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C₁₀H₁₄N₂Na₂O₈ · 2H₂O 372.24

7.444 _{(ERR 1-May-2020)} g in 1000 mL

Transfer 200 mL of 0.1 M edetate disodium VS to a 1000-mL volumetric flask. Dilute with water to volume.

Standardization: Accurately weigh about 80 mg of chelometric standard calcium carbonate, previously dried at 110° for 2 h and cooled in a desiccator, or dried according to the label instructions, 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 diluted hydrochloric acid 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 water to about 200 mL. While stirring the solution, preferably with a magnetic stirrer, add about 30 mL of the edetate disodium solution from a 50-mL buret. Adjust the solution to a pH of 12–13 with sodium hydroxide TS, add 300 mg of hydroxy naphthol blue, and continue the titration with the edetate disodium solution to a blue endpoint.

M = [(g CaCO₃)(1000)]/(100.09 x mL EDTA)

[Note—If this volumetric solution is used in a qualitative application such as pH adjustment, dissolution medium, or diluent, its standardization is not required.]