0.1 N Alcoholic Sodium Hydroxide 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-2023)
To 250 mL of alcohol add 2 mL of a 50% (w/v) solution of sodium hydroxide.
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
(USP 1-May-2023) Dissolve about 200 mg of benzoic acid, accurately weighed, in 10 mL of alcohol and 2 mL of water. Add 2 drops of phenolphthalein TS, and titrate with the alcoholic sodium hydroxide solution until a permanent pale pink color is produced.
N = [mg Benzoic Acid x (Assay/100)]/(122.1 x mL Sodium Hydroxide)
where Assay is the content/potency of benzoic acid.
1.2 Standardization with potentiometric endpoint
Dissolve about 200 mg of benzoic acid, accurately weighed, in 50 mL of alcohol and 10 mL of water. Titrate with the alcoholic sodium hydroxide solution using a combined pH electrode suitable for non-aqueous titration.
N = [mg Benzoic Acid x (Assay/100)]/(122.1 x mL Sodium Hydroxide)
where Assay is the content/potency of benzoic acid. (USP 1-May-2023)
[NOTE-If this volumetric solution is used in a qualitative application such as pH adjustment, dissolution medium, or diluent, its standardization is not required.]
