A: Infrared Absorption 197S—

B: The addition of 1 N hydrochloric acid to a Tablet produces effervescence, and the resulting solution, after having been filtered, responds to the tests for Calcium 191.

C: Heat 2 Tablets in 20 mL of 1 N sulfuric acid. Cool, add 20 mL of alcohol, mix, and allow to stand for 30 minutes. Filter this solution, and to the filtrate add 2 mL of 1 N hydrochloric acid: this solution responds to the tests for Magnesium 191.

Foaming solution— Dissolve 500 µg of FD&C Blue No. 1 and 1 g of octoxynol 9 in 100 mL of 0.1 N hydrochloric acid.

Procedure— [NOTE—For each test, use a clean, unused, 250-mL cylindrical glass jar.] Transfer a quantity of finely powdered Tablets, which has completely passed though an 80-mesh sieve, equivalent to 20 mg of simethicone, to a clean 250-mL cylindrical glass jar, fitted with a 50-mm cap, containing 100 mL of Foaming solution that has been warmed to 37. Proceed as directed for Procedure in the test for Defoaming activity under Simethicone, beginning with “Cap the jar.” The defoaming activity time does not exceed 45 seconds.

Lanthanum chloride solution— Prepare as directed in the Assay for calcium carbonate and magnesium hydroxide.

Dilute hydrochloric acid— Prepare as directed in the Assay for polydimethylsiloxane.

Standard solution— Transfer 2.542 g of sodium chloride, previously dried at 105 for 2 hours, to a 1000-mL volumetric flask, dissolve in water, dilute with water to volume, and mix. Transfer 5.0 mL of this solution to a 100-mL volumetric flask, dilute with water to volume, and mix. Transfer 4.0 mL of this solution to a second 100-mL volumetric flask containing 6.0 mL of Dilute hydrochloric acid and 2.0 mL of Lanthanum chloride solution, dilute with water to volume, and mix. This solution contains 2.0 µg of sodium (Na) per mL.

Test preparation— Transfer 3.0 mL of the aqueous layer retained from the preparation of the Assay preparation in the Assay for polydimethylsiloxane to a 50-mL volumetric flask containing 1.0 mL of Lanthanum chloride solution, dilute with water to volume, and mix.

Blank solution— Transfer 15.0 mL of Dilute hydrochloric acid and 5.0 mL of Lanthanum chloride solution to a 250-mL volumetric flask, dilute with water to volume, and mix.

Procedure— Concomitantly determine the absorbances of the Standard solution and the Test preparation at the sodium emission line at 589.0 nm with a suitable atomic absorption spectrophotometer (see Spectrophotometry and Light-Scattering 851) equipped with a sodium hollow-cathode lamp and an air–acetylene flame, using the Blank solution as the blank. Calculate the mg of sodium (Na) in each Tablet taken by the formula: in which C is the concentration, in µg per mL, of sodium in the Standard preparation; A is the average weight, in mg, of each Tablet; W is the weight, in mg, of the portion of Tablets taken to prepare the Assay preparation in the Assay for polydimethylsiloxane; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively. Each Tablet contains not more than the number of mg of sodium stated on the label.

(Official January 1, 2007)

Saccharin solution— Prepare a solution of saccharin in 4-methyl-2-pentanone containing 12.5 mg per mL.

Dilute hydrochloric acid— Mix 200 mL of hydrochloric acid with sufficient water to make 1000 mL.

Standard preparation— Dissolve a suitable quantity of USP Polydimethylsiloxane RS in 4-methyl-2-pentanone to obtain a stock solution having a known concentration of about 1 mg per mL. On the day of use, transfer 20.0 mL of this solution and 5.0 mL of Saccharin solution to a 250-mL volumetric flask, dilute with 4-methyl-2-pentanone to volume, and mix. This solution contains about 0.08 mg of USP Polydimethylsiloxane RS per mL.

Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 20 mg of polydimethylsiloxane, to a 125-mL separator. Cautiously add 50.0 mL of Dilute hydrochloric acid, and swirl until the reaction subsides. Insert the stopper, and mix. Carefully release the pressure, add 50.0 mL of 4-methyl-2-pentanone, and mix for 10 minutes. Allow the layers to separate, and drain the aqueous layer into a suitable stoppered container. [NOTE—Retain this aqueous layer for use in preparing the Assay preparation in the Assay for calcium carbonate and magnesium hydroxide and for the preparation of the Test preparation in the test for Sodium content.] Pass the organic layer through a filter containing 50 g of anhydrous sodium sulfate. Transfer 10.0 mL of the filtrate to a 50-mL volumetric flask, add 1.0 mL of Saccharin solution, dilute with methyl isobutyl ketone to volume, and mix.

Blank solution— Transfer 1.0 mL of Saccharin solution to a 50-mL volumetric flask, dilute with 4-methyl-2-pentanone to volume, and mix.

Procedure— Concomitantly determine the absorbances of the Standard preparation and the Assay preparation at the silicon emission line at 251.6 nm, with a suitable atomic absorption spectrophotometer (see Spectrophotometry and Light-Scattering 851) equipped with a silicon hollow-cathode lamp and a nitrous oxide–acetylene flame, using the Blank solution as the blank. Calculate the quantity, in mg, of polydimethylsiloxane in each Tablet taken by the formula: in which C is the concentration, in mg per mL, of USP Polydimethylsiloxane RS in the Standard preparation; A is the average weight, in mg, of each Tablet; W is the weight, in mg, of the portion of Tablets taken to prepare the Assay preparation; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.

Lanthanum chloride solution— Transfer 26.8 g of lanthanum chloride to a 200-mL volumetric flask, add 100 mL of water, and carefully add 50 mL of hydrochloric acid. Mix, and allow to cool. Dilute with water to volume, and mix.

Dilute hydrochloric acid— Prepare as directed in the Assay for polydimethylsiloxane.

Calcium stock standard solution— Transfer 499.5 mg of primary standard calcium carbonate to a 200-mL volumetric flask, and add 10 mL of water. Carefully add 5 mL of Dilute hydrochloric acid, and swirl to dissolve the calcium carbonate. Dilute with water to volume, and mix. This solution contains 1000 µg of calcium (Ca) per mL.

Magnesium stock standard solution— Transfer 1.000 g of magnesium metal to a 1000-mL volumetric flask containing 10 mL of water, slowly add 10 mL of hydrochloric acid, and swirl to dissolve the metal. Dilute with water to volume, and mix. This solution contains 1000 µg of magnesium (Mg) per mL.

Calcium and magnesium standard preparation— To a 250-mL volumetric flask add 10.0 mL of Calcium stock standard solution and 5.0 mL of Magnesium stock standard solution, dilute with water to volume, and mix. This solution contains 40 µg of calcium (Ca) and 20 µg of magnesium (Mg) per mL. On the day of use, transfer 4.0 mL of this solution to a 100-mL volumetric flask containing 2.0 mL of Lanthanum chloride solution, dilute with water to volume, and mix. This solution contains 1.6 µg of calcium (Ca) and 0.8 µg of magnesium (Mg) per mL.

Assay preparation— Transfer an accurately measured volume of the aqueous layer retained from the preparation of the Assay preparation in the Assay for polydimethylsiloxane, equivalent to about 28 mg of calcium carbonate, to a 200-mL volumetric flask, dilute with water to volume, and mix. Transfer 3.0 mL of this solution to a 100-mL volumetric flask containing 2.0 mL of Lanthanum chloride solution, dilute with water to volume, and mix.

Blank solution— Transfer 5.0 mL of Lanthanum chloride solution to a 250-mL volumetric flask, dilute with water to volume, and mix.

Procedure for calcium carbonate— Concomitantly determine the absorbances of the Standard preparation and the Assay preparation at the calcium emission line at 422.7 nm, with a suitable atomic absorption spectrophotometer (see Spectrophotometry and Light-Scattering 851) equipped with a calcium hollow-cathode lamp and an nitrous oxide–acetylene flame, using the Blank solution as the blank. Calculate the quantity, in mg, of calcium carbonate (CaCO3) in each Tablet taken by the formula: in which 100.09 is the molecular weight of calcium carbonate; 40.08 is the atomic weight of calcium; C is the concentration, in µg per mL, of calcium in the Standard preparation; V is the volume, in mL, of the aqueous layer retained from the preparation of the Assay preparation in the Assay for polydimethylsiloxane used to prepare the Assay preparation ;A is the average weight, in mg, of each Tablet; W is the weight, in mg, of the portion of Tablets taken to prepare the Assay preparation in the Assay for polydimethylsiloxane; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.

Procedure for magnesium hydroxide— Concomitantly determine the absorbances of the Standard preparation and the Assay preparation at the magnesium emission line at 285.2 nm, with a suitable atomic absorption spectrophotometer (see Spectrophotometry and Light-Scattering 851) equipped with a magnesium hollow-cathode lamp and a nitrous oxide–acetylene flame, using the Blank solution as the blank. Calculate the quantity, in mg, of magnesium hydroxide [Mg(OH)2] in each Tablet taken by the formula: in which 58.34 is the molecular weight of magnesium hydroxide; 24.305 is the atomic weight of magnesium; C is the concentration, in µg per mL, of magnesium in the Standard preparation; V is the volume, in mL, of the aqueous layer retained from the preparation of the Assay preparation in the Assay for polydimethylsiloxane used to prepare the Assay preparation; A is the average weight, in mg, of each Tablet taken; W is the weight, in mg, of the portion of Tablets taken to prepare the Assay preparation in the Assay for polydimethylsiloxane; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.