U.S. PHARMACOPEIA

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Sodium Fluoride and Acidulated Phosphate Topical Solution
» Sodium Fluoride and Acidulated Phosphate Topical Solution contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of fluoride ion.
Packaging and storage— Preserve in tight plastic containers.
Labeling— Label Topical Solution in terms of the content of sodium fluoride (NaF) and in terms of the content of fluoride ion.
pH 791— Place about 40 mL in a plastic beaker, add about 250 mg of quinhydrone, and stir for 1 minute, leaving some of the quinhydrone undissolved. Determine the pH using a hydrofluoric acid frit-junction calomel reference electrode and a hydrofluoric acid-resistant metallic electrode: the pH is between 3.0 and 4.5.
Residual solvents 467: meets the requirements.
(Official January 1, 2007)
Other requirements— It responds to the Identification tests under Sodium Fluoride and Phosphoric Acid Gel.
Assay—
Buffer solution and Standard preparations— Prepare as directed in the Assay under Sodium Fluoride Oral Solution.
Assay preparation— Transfer an accurately measured volume of Topical Solution, equivalent to about 20 mg of fluoride ion, to a 1000-mL volumetric flask, add water to dissolve, dilute with water to volume, and mix.
Procedure— Proceed as directed for Procedure in the Assay under Sodium Fluoride Oral Solution. Calculate the quantity, in mg, of fluoride ion in each mL of the Topical Solution taken by the formula:
C / V,
in which C is the determined concentration of fluoride ion, in µg per mL, in the Assay preparation, and V is the volume, in mL, of Topical Solution taken.
Auxiliary Information— Staff Liaison : Elena Gonikberg, Ph.D., Scientist
Expert Committee : (MDGRE05) Monograph Development-Gastrointestinal Renal and Endocrine
USP29–NF24 Page 1981
Phone Number : 1-301-816-8251