0.02 M Sodium Tetraphenylboron 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)
Dissolve an amount of sodium tetraphenylborate, equivalent to 6.845 g of NaB(C₆H₅)₄, in water to make 1000 mL.
[Note-Prepare this solution just before use.]
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.]
Standardization by gravimetry: Pipet two 75-mL portions of the solution into separate beakers, and to each add 1 mL of diluted acetic acid and 25 mL of water. To each beaker add, slowly and with constant stirring, 25 mL of potassium biphthalate solution (1 in 20), and allow to stand for 2 h. Filter one of the mixtures through a G4 (pore size 5–15 μm) sintered crucible, and wash the precipitate with cold water. Transfer the precipitate to a container, add 50 mL of water, shake intermittently for 30 min, filter, and use the filtrate as the saturated potassium tetraphenylborate solution in the following standardization procedure. Filter the second mixture through a tared G4 (pore size 5–15 μm) sintered crucible, and wash the precipitate with three 5-mL portions of saturated potassium tetraphenylborate solution. Dry the precipitate at 105° for 1 h. Each gram of potassium tetraphenylborate (KTPB) is equivalent to 955.1 mg of sodium tetraphenylboron.
M= (g KTPB × 0.9551) / (342.22 × 0.075 L)
Standardization with potentiometric endpoint: Accurately weigh about 50 mg of potassium biphthalate, previously crushed lightly and dried at 120° for 2 h, and dissolve in 75 mL of carbon dioxide-free water. Adjust to pH 6–8 with 1 N sodium hydroxide solution. Titrate with sodium tetraphenylboron solution using a combined potassium ion selective electrode.
M= (mg of potassium biphthalate) / (204.22 x mL Sodium tetraphenylboron)
[Note-If this volumetric solution is used in a qualitative application such as pH adjustment, dissolution medium, or diluent, its standardization is not required.]
