Aluminum Chloride
(a loo' mi num klor' ide).
AlCl3·6H2O 241.43

Aluminum chloride, hexahydrate.
Aluminum chloride hexahydrate [7784-13-6].

Anhydrous 133.34 [7446-70-0].
» Aluminum Chloride contains not less than 95.0 percent and not more than 102.0 percent of AlCl3, calculated on the anhydrous basis.
Packaging and storage— Preserve in tight containers.
Identification— A solution (1 in 10) responds to the tests for Aluminum 191 and for Chloride 191.
Water, Method I 921: between 42.0% and 48.0%.
Sulfate— The addition of 0.2 mL of barium chloride TS to 10 mL of a solution (1 in 100) produces no turbidity within 1 minute.
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, then add 6 N ammonium hydroxide until the color of the solution just 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: the weight of the residue does not exceed 2.5 mg (0.5%).
Heavy metals, Method I 231 Dissolve 1 g in 1 mL of 1 N acetic acid and sufficient water to make 25 mL: the limit is 0.002%.
Iron 241 Dissolve 1.0 g in 45 mL of water, and add 2 mL of hydrochloric acid: the limit is 0.001%.
Edetate disodium titrant— Prepare and standardize as directed in the Assay under Ammonium Alum.
Procedure— Transfer to a 250-mL volumetric flask about 5 g of Aluminum Chloride, accurately weighed, dissolve in and dilute with water to volume, and mix. Transfer 10.0 mL of the solution to a 250-mL beaker, and add, in the order named and with continuous stirring, 25.0 mL of Edetate disodium titrant, and 20 mL of acetic acid-ammonium acetate buffer TS, and boil gently for 5 minutes. Cool, and add 50 mL of alcohol and 2 mL of dithizone TS. Titrate with 0.05 M zinc sulfate VS to a bright rose-pink color. Perform a blank determination, substituting 10 mL of water for the assay preparation, and make any necessary correction. Each mL of 0.05 M Edetate disodium titrant is equivalent to 6.667 mg of AlCl3.
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Topic/Question Contact Expert Committee
Monograph Feiwen Mao, M.S.
Senior Scientific Liaison
(SM32010) Monographs - Small Molecules 3
USP35–NF30 Page 2126