Aluminum Zirconium Pentachlorohydrate

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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Al_yZr(OH)_3+4-xCl_x·nH₂O

>> Aluminum Zirconium Pentachlorohydrate is a polymeric, loosely hydrated complex of basic aluminum zirconium chloride that encompasses a range of aluminum-to-zirconium atomic ratios between 6.0:1 and 10.0:1, and a range of (aluminum plus zirconium)-to-chloride atomic ratios between 2.1:1 and 1.51:1. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of anhydrous aluminum zirconium pentachlorohydrate.

1 Packaging and storage

Preserve in well-closed containers.

2 Labeling

The label states the content of anhydrous aluminum zirconium pentachlorohydrate.

3 Identification

A solution (1 in 10) responds to the test for Chloride (191).

4 PH (791)

Between 3.0 and 5.0, in a solution [15 in 100 (w/w)].

5 ARSENIC, Method 1(211)

2 µg per g.

6 Limit of iron

Using Aluminum Zirconium Pentachlorohydrate instead of Aluminum Zirconium Octachlorohydrate, proceed as directed in the test for Limit of iron under Aluminum Zirconium Octachlorohydrate. The specified result is obtained (150 µg per g limit).

7 Content of aluminum

Using Aluminum Zirconium Pentachlorohydrate instead of Aluminum Zirconium Octachlorohydrate, proceed as directed in the test for Content of aluminum under Aluminum Zirconium Octachlorohydrate. Use the result obtained to calculate the Aluminum/zirconium atomic ratio and the (Aluminum plus zirconium)/chloride atomic ratio.

8 Content of zirconium

Using Aluminum Zirconium Pentachlorohydrate instead of Aluminum Zirconium Octachlorohydrate, proceed as directed in the test for Content of zirconium under Aluminum Zirconium Octachlorohydrate. Use the result obtained to calculate the Aluminum/zirconium atomic ratio and the (Aluminum plus zirconium)/chloride atomic ratio.

9 Aluminum/zirconium atomic ratio

Divide the percentage of aluminum found in the test for Content of aluminum by the percentage of zirconium found in the test for Content of zirconium, and multiply by 92.97/26.98, in which 92.97 is the atomic weight of zirconium corrected for 2% hafnium content, and 26.98 is the atomic weight of aluminum: the ratio is between 6.0:1 and 10.0:1.

10 Content of chloride

Using Aluminum Zirconium Pentachlorohydrate instead of Aluminum Zirconium Octachlorohydrate, proceed as directed in the test for Content of chloride under Aluminum Zirconium Octachlorohydrate. Use the result obtained to calculate the (Aluminum plus zirconium)/chloride atomic ratio.

11 (Aluminum plus zirconium)/chloride atomic ratio

Calculate the (aluminum plus zirconium)/chloride atomic ratio by the formula:

[(Al/26.98) + (Zr/92.97)]/(CI/35.453)

in which Al, Zr, and C/ are the percentages of aluminum, zirconium, and chloride, as determined in the tests for Content of aluminum, Content of zirconium, and Content of chloride, respectively; 26.98 is the atomic weight of aluminum; 92.97 is the atomic weight of zirconium corrected for 2% hafnium content; and 35.453 is the atomic weight of chlorine: the ratio is between 2.1:1 and 1.51:1.

12 Assay

Calculate the percentage of anhydrous aluminum zirconium pentachlorohydrate in the Aluminum Zirconium Pentachlorohydrate by the formula:

Al({26.98y + 92.97 +17.01[3y + 4 - (y + 1)/z] + 35.453(y + 1)/z)/26.98y)

in which Al is the percentage of aluminum found in the test for Content of aluminum, y is the aluminum/zirconium atomic ratio found in the test for Aluminum/zirconium atomic ratio, z is the (aluminum plus zirconium)/chloride atomic ratio found in the test for (Aluminum plus zirconium)/chloride atomic ratio, 26.98 is the atomic weight of aluminum, 92.97 is the atomic weight of zirconium corrected for 2% hafnium content, 17.01 is the molecular weight of the hydroxide anion (OH), and 35.453 is the atomic weight of chlorine (CI).