Potassium Citrate USP Grade Specifications:
C6H5K3O7-H2O --- 324.41
C6H5K3O7 --- 306.40
1,2,3-Propanetricarboxylic acid, 2-hydroxy-, tripotassium salt, monohydrate;
Tripotassium citrate monohydrate CAS 6100-05-6
Potassium Citrate Anhydrous CAS 866-84-2.

DEFINITION
Potassium Citrate contains NLT 99.0% and NMT 100.5% of potassium citrate (C6H5K3O7), calculated on the dried basis.

IDENTIFICATION
A. Identification Tests: General, Potassium and Citrate: A 100-mg/mL solution meets the requirements.

ASSAY
Procedure
Sample: 200 mg of Potassium Citrate
Blank: 25 mL of glacial acetic acid
Titrimetric system
Mode: Direct titration
Titrant: 0.1 N perchloric acid
Endpoint detection: Visual
Analysis: Dissolve the Sample in 25 mL of glacial acetic acid, add 2 drops of crystal violet TS, and titrate with the Titrant to a green endpoint. Perform a Blank determination.

Calculate the percentage of potassium citrate (C6H5K3O7) in the Sample taken:
Result = {[( V S − V B ) × N × F]/W} × 100

V S = Titrant volume consumed by the Sample (mL)
V B = Titrant volume consumed by the Blank ;(mL)
N = actual normality of the Titrant (mEq/mL)
F = equivalency factor, 102.1 mg/mEq
W = Sample weight (mg)
Acceptance criteria: 99.0% to 100.5% on the dried basis

Potassium Citrate BP Ph Eur Grade Specifications
C6H5K3O7-H2O -- 324.4 -- CAS 6100-05-6

DEFINITION
Potassium citrate contains not less than 99.0 per cent and not more than the equivalent of 101.0 per cent of tripotassium 2-hydroxypropane-1,2,3-tricarboxylate, calculated with reference to the anhydrous substance.

CHARACTERS
A white, granular powder or transparent crystals, hygroscopic, very soluble in water, practically insoluble in alcohol.

IDENTIFICATION
A. To 1 ml of solution S (see Tests) add 4 ml of water. The solution gives the reaction of citrates.
B. 0.5 ml of solution S gives reaction of potassium.

TESTS
Solution S: Dissolve 10.0 g in carbon dioxide-free water prepared from distilled water and dilute to 100 ml with the same solvent.
Appearance of solution: Solution S is clear and colourless.
Acidity or alkalinity: To 10 ml of solution S add 0.1 ml of PhPh solution. Not more than 0.2 ml of 0.1 M hydrochloric acid or 0.1 M sodium hydroxide is required to change the colour of the indicator.
Readily carbonizable substances: To 0.20 g of the powdered substance to be examined add 10 ml of sulphuric acid and heat in a water-bath at 90 ± 1C for 60 min. Cool rapidly. The solution is not more intensely coloured than reference solution.
Chlorides: Dilute 10 ml of solution S to 15 ml with water. The solution complies with the limit test for chlorides (50 ppm).
Oxalates: Dissolve 0.50 g in 4 ml of water, add 3 ml of hydrochloric acid and 1 g of granulated zinc and heat on a water-bath for 1 min. Allow to stand for 2 min, decant the liquid into a test-tube containing 0.25 ml of a 10 g/l solution of phenylhydrazine hydrochloride and heat to boiling. Cool rapidly, transfer to a graduated cylinder and add an equal volume of hydrochloric acid and 0.25 ml of potassium ferricyanide solution. Shake and allow to stand for 30 min. Any pink colour in the solution is not more intense than that in a standard prepared at the same time and in the same manner using 4 ml of a 0.05 g/l solution of oxalic acid (300 ppm).
Sulphates: To 10 ml of solution S add 2 ml of hydrochloric acid and dilute to 15 ml with distilled water. The solution complies with the limit test for sulphates (150 ppm).
Heavy metals: 12 ml of solution S complies with limit test A for heavy metals (10 ppm).
Sodium: Not more than 0.3 per cent of Na, determined by atomic emission spectrometry.
Water: 4.0 per cent to 7.0 per cent, determined on 0.500 g by the semi-micro determination of water. After adding the substance to be examined, stir for 15 min before titrating.