Calcium Acetate Tablets

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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1 DEFINITION 

Calcium Acetate Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of calcium acetate (C₄H₆CaO₄).  

2 IDENTIFICATION 

A. The retention time of the calcium peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay. B. Identification Tests—General 〈191〉, Chemical Identification Tests, Acetate 

Sample solution: 100 mg/mL of calcium acetate from powdered Tablets 

Acceptance criteria: Meet the requirements 

3 ASSAY 

Procedure 

Use water with a resistivity of NLT 18 megohm-cm to prepare the solutions. 

Mobile phase: 34 mM methanesulfonic acid. [Note—It is recommended to use suitable cation trapping techniques to ensure the Mobile phase is free of all cationic impurities.] 

Diluent: 0.02 N hydrochloric acid 

System suitability solution: 100 µg/mL of USP Calcium Acetate RS and 2 µg/mL of magnesium1 in Diluent 

Standard solution: 100 µg/mL of USP Calcium Acetate RS in Diluent 

Sample stock solution: Nominally 2.5 mg/mL of calcium acetate, prepared as follows. Finely powder NLT 30 Tablets and transfer an appropriate portion of the powder to a suitable container. Add 6 N hydrochloric acid to about 10% of the nal volume of the flask. Heat to boiling with constant swirling for 10 min. Allow to cool to room temperature. Transfer the solution quantitatively to a suitable volumetric  flask containing 10% of the flask volume of water. Dilute with water to volume. Pass through a suitable filter of 0.45-µm pore size. Sample solution: Nominally 100 µg/mL of calcium acetate in water, from the Sample stock solution 

Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: Conductivity with suppression 

Columns 

Guard: 5-mm × 5-cm; 5.5-µm packing L84 

Analytical: 5-mm × 25-cm; 5.5-µm packing L84 

Column temperature: 50° 

Flow rate: 1.5 mL/min 

Injection volume: 10 µL 

Run time: NLT 2.5 times the retention time of calcium 

System suitability 

Samples: System suitability solution and Standard solution 

[Note—The relative retention times for the magnesium and calcium ions are 0.8 and 1.0, respectively.] 

Suitability requirements 

Resolution: NLT 3.0 between the magnesium and calcium ions, System suitability solution 

Tailing factor: NMT 2.0, Standard solution 

Relative standard deviation: NMT 1.0%, Standard solution 

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of the labeled amount of calcium acetate (C₄H₆CaO₄) in the portion of Tablets taken: 

Result = (r_U/r_S) × (C_S/C_U) × 100 

r_U = peak response of calcium from the Sample solution 

r_S = peak response of calcium from the Standard solution 

C_S = concentration of USP Calcium Acetate RS in the Standard solution (µg/mL) 

C_U = nominal concentration of calcium acetate in the Sample solution (µg/mL) 

Acceptance criteria: 90.0%–110.0% 

4 PERFORMANCE TESTS 

Dissolution 〈711〉 

Medium: Water; 900 mL 

Apparatus 2: 50 rpm 

Time: 30 min 

Standard solution: Calcium at a known concentration in Medium 

Sample solution: Pass a portion of the solution under test through a suitable lter. Dilute with Medium to a concentration that is similar to the Standard solution, if necessary. 

Instrumental conditions 

(See Atomic Absorption Spectroscopy 〈852〉.) 

Mode: Atomic absorption spectrometry 

Analytical wavelength: 422.8 nm 

Tolerances: NLT 80% (Q) of the labeled amount of calcium acetate (C₄H₆CaO₄) is dissolved. 

Uniformity of Dosage Units 〈905〉: Meet the requirements 

5 IMPURITIES 

Change to read: 

Limit of Aluminum 

Buffer: Dissolve 50 g of ammonium acetate in 150 mL of water, adjust with glacial acetic acid to a pH of 6.0, and dilute with water to 250 mL. Aluminum standard solution: 1.0 µg/mL of aluminum. Prepare as directed in Aluminum 〈206〉, Procedure 1 

Standard solution: Prepare a solution containing 2.0 mL of Aluminum standard solution, 5 mL of Buffer, and 48 mL of water, and extract this solution with successive portions of 10, 10, and 5 mL of 0.5% 8-hydroxyquinoline in chloroform. Combine the chloroform extracts in a 50- mL volumetric flask, and dilute the combined extracts with chloroform to volume. 

Sample solution: Dissolve a portion of powdered Tablets (NLT 10) equivalent to 1.0 g of calcium acetate in 50 mL of water, and add 5 mL of Buffer. Extract this solution with successive portions of 10, 10, and 5 mL of 0.5% 8-hydroxyquinoline in chloroform. Combine the chloroform extracts in a 50-mL volumetric flask, and dilute the combined extracts with chloroform to volume. 

Blank solution: Prepare a solution containing 50 mL of water and 5 mL of Buffer. Extract this solution with successive portions of 10, 10, and 5 mL of 0.5% 8-hydroxyquinoline in chloroform. Combine the chloroform extracts in a 50-mL volumetric flask, and dilute the combined extracts with chloroform to volume. 

Instrumental conditions 

(See Fluorescence Spectroscopy 〈853〉.) 

Mode: Fluorescence 

Excitation wavelength: 392 nm 

Emission wavelength: 518 nm 

Analysis 

Samples: Standard solution, Sample solution, and Blank solution 

Use the Blank solution to zero the instrument. 

Acceptance criteria: The fluorescence of the Sample solution does not exceed that of the Standard solution (NMT 2 ppm). 

6 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Preserve in tight containers and store at controlled room temperature. 

USP Reference Standards 〈11〉 

USP Calcium Acetate RS 

¹ From commercially available National Institute of Standards and Technology (NIST)-traceable standard solution for magnesium.