0.1 N Ceric Ammonium Sulfate 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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Transfer 65 g of ceric ammonium sulfate to a 1000-mL volumetric flask containing a mixture of 30 mL of sulfuric acid and 500 mL of water. Swirl until dissolved. Cool and dilute with water to volume.

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

Transfer 25 mL of the ceric ammonium sulfate solution into an Erlenmeyer flask, and add 2 g of potassium iodide and about 150 ml of water. Mix well. Add 1 mL of starch TS and titrate immediately with freshly standardized 0.1 N sodium thiosulfate VS until the blue color disappears.

N = (ml Na₂S₂O₃ x  N Na₂S₂O₃)/ [mL Ce(NH₄)₄(SO₄)₄]

1.2 Standardization with potentiometric endpoint

Transfer 10 mL of the ceric ammonium sulfate solution into an Erlenmeyer flask, and add 2 g of potassium iodide and about 100 mL of water. Mix well. Immediately, titrate potentiometrically with freshly standardized 0.1 N sodium thiosulfate VS using a combined platinum electrode.

N = (ml Na₂S₂O₃ x  N Na₂S₂O₃)/ [mL Ce(NH₄)₄(SO₄)₄]

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

_{▲(USP 1-Dec-2021)}