Monobasic Potassium Phosphate USP NF Grade Specifications:
KH2PO4 --- 136.09
Phosphoric acid, monopotassium salt;
Monopotassium phosphate CAS 7778-77-0

DEFINITION
Monobasic Potassium Phosphate, dried at 105C for 4 h, contains NLT 98.0% and NMT 100.5% of monobasic potassium phosphate (KH2PO4).

ASSAY
Procedure
Sample solution: Transfer 5 g of Monobasic Potassium Phosphate, previously dried, to a 250-mL beaker. Add 100 mL of water and 5.0 mL of 1 N hydrochloric acid and stir until the assay specimen is completely dissolved.
Titrimetric system
Mode: Direct titration
Titrant: 1 N sodium hydroxide
Endpoint detection: Potentiometrically
Analysis: Slowly titrate the excess acid in the Sample solution, stirring constantly, with Titrant to the inflection point occurring at about pH 4 (V S1). Continue the titration with Titrant until the inflection point occurring at about pH 8.8 is reached (V S2).

V S2 = Titrant volume consumed by the Sample solution to the second inflection point (mL)
V S1 = Titrant volume consumed by the Sample solution to the first inflection point (mL)
N = actual normality of the Titrant (mEq/mL)
F = equivalency factor, 0.1361 g/mEq
W = weight of monobasic potassium phosphate taken to prepare the Sample solution (g)
Acceptance criteria: 98.0% to 100.5% on the previously dried basis.

Specifications of Potassium Dihydrogen Phosphate BP Ph Eur Grade
Monopotassium Phosphate BP
Potassium Phosphate Monobasic BP
KH2PO4 -- 136.1 -- CAS 7778-77-0
Monobasic Potassium Phosphate
Potassium Phosphate Monobasic

DEFINITION
Potassium dihydrogen phosphate contains not less than 98.0 per cent and not more than the equivalent of 100.5 per cent of KH2PO4, calculated with reference to the dried substance.

CHARACTERS
A white, crystalline powder or colourless crystals, freely soluble in water, practically insoluble in alcohol.

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.
pH: To 5 ml of solution S add 5 ml of carbon dioxide-free water. The pH of the solution is 4.2 to 4.5.
Reducing substances: To 5 ml of solution S add 5 ml of dilute sulphuric acid and 0.25 ml of 0.02 M potassium permanganate. Heat on a water-bath for 5 min. The colour of the permanganate is not completely discharged.
Chlorides: Dilute 2.5 ml of solution S to 15 ml with water R. The solution complies with the limit test for chlorides (200 ppm).
Sulphates: To 5 ml of solution S add 0.5 ml of hydrochloric acid and dilute to 15 ml with distilled water. The solution complies with the limit test for sulphates (300 ppm).
Arsenic: 0.5 g complies with limit test A for arsenic (2 ppm).
Iron: 10 ml of solution S complies with the limit test for iron (10 ppm).
Sodium: If intended for use in the manufacture of parenteral dosage forms, it complies with the test for sodium. Not more than 0.1 per cent of Na, determined by atomic emission spectrometry
Heavy metals: 12 ml of solution S complies with limit test A for heavy metals (10 ppm).
Loss on drying: Not more than 2.0 per cent, determined on 1.000 g by drying in an oven at 125C to 130C.

Potassium Phosphate Monobasic FCC Food Grade
Potassium Biphosphate; Potassium Dihydrogen Phosphate
Monopotassium Phosphate FCC
Monobasic Potassium Phosphate FCC
KH2PO4 Formula weight 136.09
INS: 340(i) CAS: 7778-77-0

DESCRIPTION
Potassium Phosphate, Monobasic, occurs as colorless crystals or as a white, granular or crystalline powder. It is stable in air. It is freely soluble in water, but is insoluble in alcohol. The pH of a 1:100 aqueous solution is between 4.2 and 4.7.
Function: Buffer; sequestrant; yeast food.

REQUIREMENTS
Identification: A 1:20 aqueous solution gives positive tests for Potassium and for Phosphate.
Assay: Not less than 98.0% of KH2PO4 after drying.
Arsenic: Not more than 3 mg/kg.
Fluoride: Not more than 10 mg/kg.
Insoluble Substances: Not more than 0.2%.
Lead: Not more than 2 mg/kg.
Loss on Drying: Not more than 1%.

Specifications of Potassium Phosphate Monobasic Analytical Reagent Grade
Potassium Dihydrogen Phosphate
Monopotassium Phosphate
Monobasic Potassium Phosphate
KH2PO4
Formula weight 136.09
CAS Number 7778-77-0

REQUIREMENTS
Assay: 99.0% KH2PO4
pH of a 5% solution: 4.1-4.5 at 25C

MAXIMUM ALLOWABLE
Insoluble matter: 0.01%
Loss on drying at 105C: 0.2%
Chloride (Cl): 0.001%
Nitrogen compounds (as N): 0.001%
Sulfate (SO4): 0.003%
Heavy metals (as Pb): 0.001%
Iron (Fe): 0.002%
Sodium (Na): 0.005%.