Aluminum Chlorohydrate
Aly(OH)3y-zClz·H2O

Aluminum chlorohydroxide.
Aluminum hydroxychloride.
Dihydrate [12042-91-0].

Anhydrous [1327-41-9].

Aluminum chlorohydroxide,dihydrate.
Aluminum hydroxychloride,dihydrate.
Dihydrate 210.48 [12042-91-0].

Anhydrous 174.45 [1327-41-9].
»Aluminum Chlorohydrate consists of complex basic aluminum chloride that is polymeric and loosely hydrated and encompasses a range of aluminum-to-chloride atomic ratios between 1.91:1and 2.10:1.It contains the equivalent of not less than 90.0percent and not more than 110.0percent of the labeled amount of anhydrous aluminum chlorohydrate.
Packaging and storage— Preserve in well-closed containers.
Labeling— The label states the content of anhydrous aluminum chlorohydrate.
Identification— Asolution (1in 10)responds to the tests for Aluminum á191ñand for Chloride á191ñ.
pHá791ñ: between 3.0and 5.0,in a solution [15in 100(w/w)].
Limit of iron—
Standard preparation— Transfer 2.0mLof Standard Iron Solution,prepared as directed under Iron á241ñ,to a 50-mLbeaker.
Test preparation— Transfer 2.7g of Aluminum Chlorohydrate to a 100-mLvolumetric flask,dilute with water to volume,and mix.Transfer 5.0mLof this solution to a 50-mLbeaker.
Procedure— To each of the beakers containing the Standard preparationand the Test preparationadd 5mLof 6Nnitric acid,cover with a watch glass,and boil on a hot plate for 3to 5minutes.Allow to cool,add 5mLof Ammonium Thiocyanate Solution,prepared as directed under Iron á241ñ,transfer to separate 50-mLcolor comparison tubes,dilute with water to volume,and mix:the color of the solution from the Test preparationis not darker than that of the solution from the Standard preparation(150µg per g).
Content of aluminum—
Edetate disodium titrant— Prepare and standardize as directed in the Assayunder Ammonium Alum,except to use 37.2g of edetate disodium instead of 18.6g.
Test solution— Transfer about 200mg of Aluminum Chlorohydrate,accurately weighed,to a 250-mLbeaker,add 20mLof water and 5mLof hydrochloric acid,boil on a hot plate for not less than 5minutes,and allow to cool.
Procedure— To the Test solutionadd 25.0mLof Edetate disodium titrant,and adjust with 2.5Nammonium hydroxide or 1Nacetic acid to a pHof 4.7±0.1.Add 20mLof acetic acid-ammonium acetate buffer TS,50mLof alcohol,and 5mLof dithizone TS.The pHof this solution should be 4.7±0.1.Titrate with 0.1Mzinc sulfate VSuntil the color changes from green-violet to rose-pink.Perform a blank titration,and make any necessary correction.Each mLof 0.1MEdetate disodium titrantconsumed is equivalent to 2.698mg of aluminum (Al).Use the aluminum content thus obtained to calculate the Aluminum/chloride atomic ratio.
Content of chloride— Transfer about 700mg of Aluminum Chlorohydrate,accurately weighed,to a 250-mLbeaker,and add 100mLof water and 10mLof diluted nitric acid with stirring.Titrate with 0.1Nsilver nitrate VSusing a glass silver-silver chloride electrode and a silver billet electrode system,determining the endpoint potentiometrically.Each mLof 0.1Nsilver nitrate is equivalent to 3.545mg of chloride (Cl).Use the chloride content thus obtained to calculate the Aluminum/chloride atomic ratio.
Aluminum/chloride atomic ratio— Divide the percentage of aluminum found in the test for Content of aluminumby the percentage of chloride found in the test for Content of chloride,and multiply by 35.453/26.98,in which 35.453and 26.98are the atomic weights of chlorine and aluminum,respectively:the ratio is between 1.91:1and 2.10:1.
Assay— Calculate the percentage of anhydrous aluminum chlorohydrate in the Aluminum Chlorohydrate by the formula:
Al({26.98x +[17.01(3x -1)]+35.453}/26.98x),
in which Alis the percentage of aluminum as obtained in the test for Content of aluminum,xis the aluminum/chloride atomic ratio,26.98is the atomic weight of aluminum,17.01is the molecular weight of the hydroxide anion (OH),and 35.453is the atomic weight of chlorine (Cl).
Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 88
Phone Number:1-301-816-8389