Assay preparation
Transfer about 1000mg of Cream,accurately weighed,to a 100-mLvolumetric flask,dissolve in 60mLof methanol,mix vigorously for 2minutes,and dilute with methanol to volume.Heat at 45

for 5minutes,and cool to room temperature.
Procedure
Separately inject equal volumes (about 15µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C
21H
21N·HCl in the portion of Cream taken by the formula:
100C(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Naftifine Hydrochloride RSin the
Standard preparation,and
rUand
rSare the peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.