0.1 N Ammonium Thiocyanate 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-Aug-2020)}

Dissolve about 8 g of ammonium thiocyanate in 1000 mL of water.

1 Standardization

^▲See Volumetric Solutions, 1. Definitions.

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-Aug-2020)} Accurately measure about 30 mL of 0.1 N silver nitrate VS into a glass-stoppered flask. Dilute with 50 mL of water, then add ^▲2 mL of nitric acid and 2 mL of ferric ammonium sulfate TS, and titrate with the ammonium thiocyanate solution to the first appearance of a red-brown color. _{▲(USP 1-Aug-2020)}

N = (mL AgNO₃ x NAgNO₃)/ (mL NH₄SCN Solution)

If desirable, 0.1 N ammonium thiocyanate may be replaced by 0.1 N potassium thiocyanate where the former is directed in various tests and assays.

^▲Standardization with potentiometric endpoint: Accurately measure about 10 mL of 0.1 N silver nitrate VS into a glass-stoppered flask. Dilute with 50 mL of water, add 2 mL of nitric acid, and titrate potentiometrically with the ammonium thiocyanate solution using a silver indicating electrode and an appropriate reference electrode or a combined silver electrode.

N = (mL AgNO₃ x NAgNO₃)/ (mL NH₄SCN Solution)

If desirable, 0.1 N ammonium thiocyanate may be replaced by 0.1 N potassium thiocyanate where the former is directed in various tests and assays _{▲(USP 1-Aug-2020)}

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