Calcium Carbonate Oral Suspension DEFINITION Calcium Carbonate Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of calcium carbonate (CaCO3). IDENTIFICATION • A. Identification TestsGeneral, Calcium 191: The addition of acetic acid to it produces effervescence (presence of carbonate). The resulting solution, after boiling, meets the requirements. ASSAY • Procedure Sample solution: Transfer a portion of Oral Suspension, equivalent to 1 g of calcium carbonate, previously well shaken in its original container, to a beaker with the aid of 25 mL of water. Add 20 mL of 1 N hydrochloric acid. Heat on a steam bath for 30 min. Allow to cool, and transfer with the aid of water to a 100-mL volumetric flask. Dilute with water to volume. Mix, and filter. Blank: 100 mL of water, 15 mL of 1 N sodium hydroxide, and 5 mL of triethanolamine Titrimetric system (See Titrimetry 541.) Mode: Direct titration Titrant: 0.05 M edetate disodium VS Indicator: 100 mg of hydroxy naphthol blue Endpoint detection: Visual, change to distinct blue Analysis: Transfer 20.0 mL of the Sample solution to a suitable container. Dilute with water to 100 mL. Add 15 mL of 1 N sodium hydroxide, 5 mL of triethanolamine, and 100 mg of hydroxy naphthol blue. Titrate with the Titrant. Calculate the percentage of the labeled amount of calcium carbonate (CaCO3) in the sample taken: Result = [(VS VB) × M × F × 100]/W
Acceptance criteria: 90.0%110.0% IMPURITIES • Limit of Fluoride [NotePrepare and store all solutions in plastic containers. ] Solution A: 294 mg/mL of sodium citrate dihydrate in water Standard stock solution: 1.1 mg/mL of USP Sodium Fluoride RS in water Standard solution: Combine 20.0 mL of the Standard stock solution with 50.0 mL of Solution A, and dilute with water to 100.0 mL. [NoteEach mL of this solution contains 100 µg of fluoride ion. ] Sample solution: Transfer a portion of Oral Suspension, equivalent to 2.0 g of calcium carbonate, to a beaker containing a plastic-coated stirring bar. Add 20 mL of water and 4.0 mL of hydrochloric acid. Stir until dissolved. Add 50.0 mL of Solution A and sufficient water to make 100.0 mL. Electrode system: Use a fluoride-specific ion-indicating electrode and a silversilver chloride reference electrode connected to a pH meter capable of measuring potentials with a minimum reproducibility of ±0.2 mV (see pH 791). Standard response line: Transfer 50.0 mL of Solution A and 4.0 mL of hydrochloric acid to a beaker. Add water to make 100.0 mL. Add a plastic-coated stirring bar, insert the electrodes into the solution, and stir for 15 min. Read the potential, in mV. Continue stirring, and at 5-min intervals add 100, 100, 300, and 500 µL of the Standard solution, reading the potential 5 min after each addition. Plot the logarithms of the cumulative fluoride ion concentrations (0.1, 0.2, 0.5, and 1.0 µg/mL) versus potential, in mV. Analysis: Rinse and dry the electrodes, and insert them into the Sample solution. Stir for 5 min, and read the potential, in mV. From the measured potential and the Standard response line, determine the concentration, C, in µg/mL, of fluoride ion in the Sample solution. Calculate the content of fluoride in the sample taken: Result = (V × C)/W
Acceptance criteria: 50 µg/g, with respect to the labeled amount of calcium carbonate • Arsenic, Method I 211 Test preparation: Slowly dissolve a portion of Oral Suspension equivalent to 1.0 g of calcium carbonate in 15 mL of hydrochloric acid. Dilute with water to 55 mL. Analysis: Proceed as directed in the chapter, except omit the addition of 20 mL of 7 N sulfuric acid specified under Procedure. Acceptance criteria: NMT 3 µg/g, with respect to the labeled amount of calcium carbonate • Lead 251 Test preparation: Mix a portion of Oral Suspension equivalent to 1.0 g of calcium carbonate in 5 mL of water. Analysis: To the Test preparation slowly add 8 mL of 3 N hydrochloric acid. Evaporate on a steam bath to dryness, and dissolve the residue in 5 mL of water. Acceptance criteria: NMT 3 µg/g, with respect to the labeled amount of calcium carbonate • Heavy Metals 231 Test preparation: Mix a portion of Oral Suspension equivalent to 1.0 g of calcium carbonate with 5 mL of water. Slowly add 8 mL of 3 N hydrochloric acid, and evaporate on a steam bath to dryness. Dissolve the residue in 20 mL of water. Filter, and add water to the filtrate to make 25 mL. Acceptance criteria: NMT 20 µg/g, with respect to the labeled amount of calcium carbonate SPECIFIC TESTS • Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62: The total aerobic microbial count is NMT 102 cfu/mL. It meets the requirements of the tests for absence of Escherichia coli and Pseudomonas aeruginosa. • pH 791: 7.58.7 ADDITIONAL REQUIREMENTS • Packaging and Storage: Preserve in tight containers, and avoid freezing. • USP Reference Standards 11 USP Sodium Fluoride RS Auxiliary Information Please check for your question in the FAQs before contacting USP.
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