0.1 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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^▲_{▲(USP 1-May-2021)}

Dissolve 37.22 g of edetate disodium in water to make 1000 mL.

1 Standardization

See Volumetric Solutions, 1. Introduction.

See Titrimetry (541)

Standardize by one of the following procedures. [NOTE-Other standardization procedures may be used. See Volumetric Solutions, 2. Preparation and Standardization. 2.3 Standardization.]

1.1 Standardization with visual endpoint

_{▲(USP 1-May-2021)} Accurately weigh about 400 mg of chelometric standard calcium carbonate, previously dried at ^▲210° for 4 h_{▲(USP 1-May-2021)} 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. Swirl the contents of the beaker to dissolve the calcium carbonate. 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 = [(gCaCO₃) x (Assay/100) x 1000] / (100.09 x mL EDTA) 

1.2 Standardization with potentiometric endpoint

Accurately weigh about 100 mg of chelometric standard calcium carbonate, previously dried at 210° for 4 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 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. 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 100 mL. Adjust the solution to a pH of 12-13 with sodium hydroxide TS and titrate potentiometrically with the edetate disodiurn solution using a combined calcium ion-selective electrode.

M = [(gCaCO₃) x (Assay/100) x 1000] / (100.09 x mL EDTA)  _{▲(USP 1-May-2021)}

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