0.05 M Edetate Disodium VS
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
(USP 1-May-2021)
Dissolve 18.6 g of edetate disodium in water to make 1000 mL.
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.]
Standardization with visual endpoint: (USP 1-May-2021) Accurately weigh about 200 mg of chelometric standard calcium carbonate, previously dried according to the label instructions or, if this information is not available, at 210° for 4 h. (USP 1-May-2021) 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 2 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. 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 with sodium hydroxide TS to a pH of 12-13, add (USP 1-May-2021) 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 mLEDTA)
Standardization with potentiometric endpoint: Accurately weigh about 50 mg of chelometric standard calcium carbonate, previously dried according to the label instructions or, if this information is not available, at 210° for 4 h, 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 0.5 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 pipet, and the watch glass with water, and dilute with water to about 100 mL. Add 4 mL of sodium hydroxide TS and titrate with the edetate disodium solution using a combined calcium ion-selective electrode.
M = [(gCaCO3) x (Assay/100) x 1000]/(100.09 x mLEDTA)
(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.]
