Specifications of Potassium Alum USP
AlK(SO4)2-12H2O --- 474.39
Sulfuric acid, aluminum potassium salt (2:1:1), dodecahydrate.
Aluminum potassium sulfate (1:1:2) dodecahydrate CAS 7784-24-9
Anhydrous 258.21 CAS 10043-67-1

Potassium Alum contains not less than 99.0 percent and not more than 100.5 percent of AlK(SO4)2, calculated on the dried basis.

Loss on drying: Transfer 2.0 g, in a tarred porcelain crucible, to a muffle furnace at 200. Increase the temperature to 400 , and dry at 400 to constant weight. Cool in a desiccator, and weigh: it loses between 43.0% and 46.0% of its weight.
Heavy metals:the limit is 0.002%.
Iron: Add 5 drops of potassium ferrocyanide TS to 20 mL of a solution (1 in 150): no blue color is produced immediately.

REQUIREMENTS
Identification: A 1:20 aqueous solution gives positive tests for Aluminum, for Potassium, and for Sulfate.
Assay: Not less than 99.5% and not more than 100.5% of AlK(SO4)2·12H2O.
Ammonium Salts: Passes test.
Fluoride: Not more than 0.003%.
Lead: Not more than 3 mg/kg.
Selenium: Not more than 0.003%.

Specifications of Alum BP
Potash Alum BP
Aluminium Potassium Sulphate BP
AlK(SO4)2-12H2O -- 474.4 -- CAS 7784-24-9

REQUIREMENTS
Assay: 98.0-102.0% AlK(SO4)2 .12H2O

Specifications of Alum BP
Potash Alum BP
Aluminium Potassium Sulphate BP
AlK(SO4)2-12H2O -- 474.4 -- CAS 7784-24-9

IDENTIFICATION
A. Solution S (see Tests) gives the reactions of sulphates.
B. Solution S gives the reaction of aluminium.
C. Shake 10 ml of solution S with 0.5 g of sodium bicarbonate R and filter. The filtrate gives reaction (a) of potassium.

Aluminum Potassium Sulfate Dodecahydrate Analytical Reagent
Potash Alum
AlK(SO4)2 . 12H2O
Formula Wt 474.39
CAS Number 7784-24-9

REQUIREMENTS
Assay: 98.0-102.0% AlK(SO4)2 .12H2O

MAXIMUM ALLOWABLE
Insoluble matter: 0.005%
Chloride (Cl): 5 ppm
Ammonium (NH4): 0.005%
Heavy metals (as Pb): 0.001%
Iron (Fe): 0.001%
Sodium (Na): 0.02%