Medium: water; 900 mL.

Apparatus 2: 50 rpm.

Time: 2 hours.

Potassium stock solution— Prepare as directed in the Assay under Potassium Chloride Oral Solution.

Standard solutions— Prepare as directed for Standard preparations in the Assay under Potassium Chloride Oral Solution.

Procedure— Filter the solution under test, and dilute quantitatively with Dissolution Medium to obtain a test solution containing about 60 µg of potassium chloride per mL. Place 5.0 mL of the test solution in a 100-mL volumetric flask, add 2.0 mL of sodium chloride solution (1 in 5) and 1.0 mL of hydrochloric acid, dilute with water to volume, mix, and proceed as directed for Procedure in the Assay under Potassium Chloride Oral Solution. Calculate the quantity, in mg, of KCl dissolved by the formula: in which F is the extent of dilution of the solution under test, and the other terms are as defined therein.

Tolerances— Not more than 35% (Q) of the labeled amount of KCl is dissolved in 2 hours. The requirements are met if the quantities dissolved from the Tablets tested conform to the accompanying acceptance table instead of the table shown under Dissolution 711.

(Official January 1, 2007)

Potassium stock solution and Standard preparations— Prepare as directed in the Assay under Potassium Chloride Oral Solution.

Assay preparation 1— Place not fewer than 20 Tablets in a suitable container with 400 mL of water, heat to boiling, and boil for 20 minutes. Allow to cool, transfer the solution to a 1000-mL volumetric flask, dilute with water to volume, and mix. Filter, discarding the first 20 mL of the filtrate. Transfer an accurately measured volume of the subsequent filtrate, equivalent to about 60 mg of potassium chloride, to a 1000-mL volumetric flask, dilute with water to volume, and mix.

Assay preparation 2 (For formulations containing crystals coated with hydrophobic polymers)— Place not fewer than 20 Tablets in a 2000-mL volumetric flask. Add 1200 mL of a mixture of acetonitrile and water (1:1), and shake by mechanical means, or stir using a magnetic bar for 90 minutes. Dilute with the mixture of acetonitrile and water (1:1) to volume Allow to stand for 90 minutes. Pass through a filter having a 0.2-µm porosity. Transfer an accurately measured volume of the filtrate, quantitatively dilute with water to obtain a solution having a concentration of about 0.06 mg per mL, and mix. [NOTE—Retain a portion of the filtrate for use in the test for Identification.]. Transfer 5.0 mL of the resulting solution to a 100-mL volumetric flask, add 2.0 mL of sodium chloride solution (1 in 5) and 1.0 mL of hydrochloride acid, dilute with water to volume, and mix.

Procedure— Proceed as directed in the Assay under Potassium Chloride Oral Solution. Calculate the quantity, in mg, of potassium chloride (KCl) in each Tablet taken by the formula: in which T is the labeled quantity, in mg, of potassium chloride in each Tablet; D is the concentration, in µg per mL, of potassium chloride in the designated Assay preparation, based on the labeled quantity per Tablet and the extent of dilution; and the other terms are as defined therein.