Sodium Fluoride and Acidulated Phosphate Topical Solution
»Sodium Fluoride and Acidulated Phosphate Topical Solution contains not less than 90.0percent and not more than 110.0percent 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.
pHá791ñ— Place about 40mLin a plastic beaker,add about 250mg of quinhydrone,and stir for 1minute,leaving some of the quinhydrone undissolved.Determine the pHusing a hydrofluoric acid frit-junction calomel reference electrode and a hydrofluoric acid-resistant metallic electrode:the pHis between 3.0and 4.5.
Other requirements— It responds to the Identificationtests under Sodium Fluoride and Phosphoric Acid Gel.
Assay—
Buffer solution andStandard preparations— Prepare as directed in the Assayunder Sodium Fluoride Oral Solution.
Assay preparation— Transfer an accurately measured volume of Topical Solution,equivalent to about 20mg of fluoride ion,to a 1000-mLvolumetric flask,add water to dissolve,dilute with water to volume,and mix.
Procedure— Proceed as directed for Procedurein the Assayunder Sodium Fluoride Oral Solution.Calculate the quantity,in mg,of fluoride ion in each mLof the Topical Solution taken by the formula:
C/V,
in which Cis the determined concentration of fluoride ion,in µg per mL,in the Assay preparation,and Vis the volume,in mL,of Topical Solution taken.
Auxiliary Information— Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 1785
Phone Number:1-301-816-8251
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