Sodium Fluoride 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

Sodium Fluoride Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of sodium fluoride (NaF).

2 IDENTIFICATION

A. Identification Tests—General 〈191〉, Chemical Identification Tests, Sodium

Sample solution: Disperse 20 finely powdered Tablets in 25 mL of water, shake, and filter. Use the filtrate.

Acceptance criteria: The filtrate meets the requirements.

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B. The retention time of the fluoride peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

(USP 1-May-2020)

3 ASSAY

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3.1 Procedure

[Note—Store all solutions in plastic containers. It is recommended to use plastic HPLC vials. Use water with a resistivity of NLT 18

megohm-cm to prepare the solutions.]

Solution A: 100 mM of potassium hydroxide in water

Solution B: Water

Mobile phase: See Table 1. Alternatively, Mobile phase can be generated electrolytically using an automatic eluant generator.

Table 1

System suitability solution: 2.0 μg/mL of USP Sodium Fluoride RS and 1.0 μg/mL of USP Sodium Acetate RS in water

Standard solution: 2.0 μg/mL of USP Sodium Fluoride RS in water

Sample stock solution: Nominally 20 μg/mL of sodium fluoride prepared as follows. Finely powder NLT 20 Tablets and transfer an appropriate portion of the powder to a suitable volumetric flask. Add about 40% of the final volume of water. Shake for about 30 min and dilute with water to volume.

Sample solution: Nominally 2.0 μg/mL of sodium fluoride in water from the Sample stock solution prepared as follows. Transfer an appropriate amount of well-mixed Sample stock solution to a suitable volumetric flask. Dilute with water to volume and mix well. Centrifuge a portion of the solution and use the clear supernatant. [Note—Centrifuging at a speed of 8000 rpm for 10 min may be suitable.]

3.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: Conductivity with suppression

Columns

Guard: 4.0-mm × 0.5-cm; 4.6-μm packing L91

Analytical: 4.0-mm × 25-cm; 4.6-μm packing L91

Column temperature: 40°

Flow rate: 1.0 mL/min

Injection volume: 20 μL

3.3 System suitability

Samples: System suitability solution and Standard solution

[Note—The relative retention times for fluoride and acetate ions are 1.0 and 1.3, respectively.]

3.4 Suitability requirements

Resolution: NLT 1.5 between fluoride and acetate ions, System suitability solution

Tailing factor: NMT 2.0, Standard solution

Relative standard deviation: NMT 2.0%, Standard solution

3.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of sodium fluoride (NaF) in the portion of Tablets taken:

Result = (r_U/r_S ) × (C_S /C_U) × 100

r_U = peak response of fluoride ion from the Sample solution

r_S = peak response of fluoride ion from the Standard solution

C_S = concentration of USP Sodium Fluoride RS in the Standard solution (μg/mL)

C_U = nominal concentration of sodium fluoride in the Sample solution (μg/mL) (USP 1-May-2020)

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

Disintegration 〈701〉: NMT 15 min

Uniformity of Dosage Units 〈905〉: Meet the requirements

5 ADDITIONAL REQUIREMENTS

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Packaging and Storage: Preserve in tight containers. Store at controlled room temperature. (USP 1-May-2020)

Labeling: Label the Tablets in terms of the content of sodium fluoride (NaF) and in terms of the content of fluoride ion. Tablets that are to be chewed may be labeled as Sodium Fluoride Chewable Tablets.

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USP Reference Standards 〈11〉

USP Sodium Acetate RS (USP

USP Sodium Fluoride RS