Aluminum Sulfate
(a loo' mi num sul' fate).
Al2(SO4)3·xH2O (anhydrous)
342.15
342.15Sulfuric acid, aluminum salt (3:2), hydrate.
Aluminum sulfate (2:3) hydrate
[17927-65-0].Anhydrous 342.16
[10043-01-3].» Aluminum Sulfate contains not less than 54.0 percent and not more than 59.0 percent of Al2(SO4)3. It contains a varying amount of water of crystallization.
Packaging and storage—
Preserve in well-closed containers.
Identification—
A solution (1 in 10) responds to the tests for Aluminum and for Sulfate 
191
.
191.
pH 791:
not less than 2.9, in a solution (1 in 20).
791:
not less than 2.9, in a solution (1 in 20).
Water, Method I 921:
not less than 41.0% and not more than 46.0%.
921:
not less than 41.0% and not more than 46.0%.
Heavy metals 231—
Dissolve 1.0 g in 2 mL of 1 N acetic acid, and dilute with water to 25 mL. The limit is 20 µg per g.
231—
Dissolve 1.0 g in 2 mL of 1 N acetic acid, and dilute with water to 25 mL. The limit is 20 µg per g.
Limit of alkalies and alkaline earths—
To a boiling solution of 1.0 g in 150 mL of water add a few drops of methyl red TS and then add 6 N ammonium hydroxide just until the color of the solution changes to a distinct yellow. Add hot water to restore the volume to 150 mL, and filter while hot. Evaporate 75 mL of the filtrate to dryness, and ignite to constant weight: not more than 2 mg of residue remains (0.4%).
Limit of ammonium salts—
Heat 1 g with 10 mL of 1 N sodium hydroxide on a steam bath for 1 minute: the odor of ammonia is not perceptible.
Iron—
To 20 mL of a solution (1 in 150) add 0.3 mL of potassium ferrocyanide TS: no blue color is produced immediately.
Assay—
Edetate disodium titrant—
Prepare and standardize as directed in the Assay under Ammonium Alum.
Procedure—
Transfer about 7.5 g of Aluminum Sulfate, accurately weighed, to a 250-mL volumetric flask, and dissolve in water. Dilute with water to volume, mix, and pipet 10 mL of the solution into a 250-mL beaker. Proceed as directed in the Assay for aluminum oxide under Aluminum Acetate Topical Solution, beginning with “add, in the order named.” Each mL of 0.05 M Edetate disodium titrant is equivalent to 8.554 mg of Al2(SO4)3.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Behnam Davani, Ph.D., M.B.A.
Senior Scientific Liaison 1-301-816-8394 |
(SM12010) Monographs - Small Molecules 1 |
USP35–NF30 Page 2136