0.1 M Tetramethylammonium Bromide 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-Dec-2022)
Dissolve 15.41 g of tetramethylammonium bromide (CH3)4NBr (USP 1-Dec-2022) 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-Dec-2022) Transfer an accurately measured volume of about 40 mL of the solution to a beaker, add 10 mL of diluted nitric acid and 50.0 mL of 0.1 N silver nitrate VS, and mix. Add 2 mL of ferric ammonium sulfate TS, and titrate the excess silver nitrate with 0.1 N ammonium thiocyanate VS.
M = {[50.0 - [(ml NH4SCN x N NH4SCN)]/N AgNO3] x N AgNO3}/[ml (CH3)4NBr]
Standardization with potentiometric endpoint: Transfer an accurately measured volume of about 10 mL of the solution to a flask, add 2 mL of diluted nitric acid, and titrate with 0.1 N silver nitrate VS using a combined silver electrode.
M = (ml AgNO3 x N AgNO3)/[ml (CH3)4NBr] (USP 1-Dec-2022)
[NOTE-If this volumetric solution is used in a qualitative application such as pH adjustment, dissolution medium, or diluent, its standardization is not required.]
