Description

Potassium Bitartrate USP

Potassium Bitartrate (Also called Cream of Tartar)
C4H5KO6 **8.*8
Butanedioic acid 2,*-dihydroxy-, [R-(R*,R*)]-, monopotassium salt.
Potassium hydrogen tartrate [*******4].

Potassium Bitartrate, dried at **5 for 3 hours, contains not less than *9.0 percent and not more than **1.0 percent of C4H5KO6.

Identification—
A: Ignite it: it leaves a residue that imparts a reddish purple color to a non-luminous flame.
B: A saturated solution of Potassium Bitartrate yields a yellowish orange precipitate with sodium cobalt nitrite TS.
C: A solution (1 in *0 of Potassium Bitartrate) responds to the tests for Tartrate.
Insoluble matter— Mix **0 mg of it with 3 mL of 6 N ammonium hydroxide: no un-dissolved residue remains.
Limit of ammonia—
Sodium hypochlorite solution— Use a commercially available solution that contains between 4.0% and 6.0% of sodium hypochlorite.
Oxidizing solution— [NOTE—Prepare on the day of use.] Prepare a mixture of alkaline sodium citrate TS and Sodium hypochlorite solution (4:1).
Diluted sodium nitroferricyanide solution— Prepare a mixture of water and sodium nitroferricyanide TS (*0:1).
Standard solution— Transfer **0 mg of ammonium chloride, previously dried over silica gel for 4 hours, to a *-L volumetric flask, and dilute with water to volume. This solution contains **0 =g of ammonia per mL. Dilute this solution quantitatively, and stepwise if necessary, with water to obtain a solution having a concentration of 0.*5 =g of ammonia per mL.
Test solution— Transfer **0 mg of Potassium Bitartrate to a ***-mL volumetric flask, and dissolve in and dilute with water to volume. Heat gently to facilitate the dissolution.
Procedure— [NOTE—Carefully follow the order of addition stated below.] Separately transfer 6.0 mL each of the Standard solution and the Test solution to two color-comparison tubes. To each tube add 0.4 mL of phenol TS, 0.4 mL of Diluted sodium nitroferricyanide solution, and 1.0 mL of Oxidizing solution. Dilute with water to *0 mL, mix, and allow to stand for 1 hour: the color of the Test solution is not darker than the color of the Standard solution (0.*1%).
Heavy metals— the limit is 0.**2%.

Potassium Bitartrate; Cream of Tartar
KOOCCH(OH)CH(OH)COOH
C4H5KO6 Formula wt **8.*8
INS: **6 CAS: [*******4]

DESCRIPTION
Potassium Acid Tartrate occurs as colorless or slightly opaque crystals, or as a white, crystalline powder. It is a salt of L(+)- tartaric acid. One gram dissolves in **5 mL of water at *5°, in *6 mL of boiling water, and in ***0 mL of alcohol. A saturated solution is acid to litmus.
Function: Acidifier; buffer.

REQUIREMENTS
Identification:
A. When sufficiently heated, a sample chars and emits flammable vapors having an odor resembling that of burning sugar. At a higher temperature and with free access to air, the heat consumes the carbon of the black residue, and a white, fused mass of potassium carbonate remains that imparts a red-purple color to a non-luminous flame.
B. Mix a saturated solution of sample with sodium cobalt nitrite TS. A yellow-orange precipitate forms.
C. Neutralize a saturated solution of sample with 1 N sodium hydroxide in a test tube, add silver nitrate TS, then just sufficient 6 N ammonium hydroxide to dissolve the white precipitate, and boil the solution. A mirror forms on the inner surface of the test tube from the silver deposited there.
Assay: Not less than *9.0% and not more than **1.0% of C4H5KO6 after drying.
Ammonia: Passes test.
Insoluble Matter: Passes test.
Lead: Not more than 2 mg/kg.