0.1 N Bromine 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 3 g of potassium bromate and 15 g of potassium bromide in water to make 1000 mL. ^▲Preserve in dark amber-colored, glass- stoppered bottles_{▲(USP 1-Aug-2020)}

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.]

1.1 Standardization with visual endpoint

_{▲(USP 1-Aug-2020)} Accurately measure about 25 mL of the solution into a 500-mL iodine flask, and dilute with 120 mL of water. Add 5 mL of hydrochloric acid, insert the stopper in the flask, and shake it gently. Then add 5 mL of potassium iodide TS, again insert the stopper, shake the mixture, allow it to stand for 5 min, and titrate the liberated iodine with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the endpoint is approached.

^▲_{▲(USP 1-Aug-2020)}

N = (mL. Na₂S₂O_3 ^x N Na₂S₂O₃)/ (mL Br₂ solution)

1.2 Standardization with potentiometric endpoint

Accurately measure 10 mL of the solution into a 500-mL iodine flask, and dilute with 120 mL of water. Add 2 mL of hydrochloric acid, insert the stopper in the flask, and shake it gently. Then add 2 mL of potassium iodide TS, again. insert the stopper, shake the mixture, allow it to stand for 5 min, and titrate the liberated iodine potentiometrically with 0.1 N sodium thiosulfate VS using a combined platinum electrode.

N = (mL. Na₂S₂O_3 ^x N Na₂S₂O₃)/ (mL Br₂ solution) _{▲(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.]