Identification—
A:
Dilute a volume of Topical Solution to a concentration of about 40 µg of cetylpyridinium chloride per mL: the UV absorption spectrum of the resulting solution exhibits maxima and minima at the same wavelengths as that of a similar solution of
USP Cetylpyridinium Chloride RS, concomitantly measured.
B:
Evaporate a volume of Topical Solution, equivalent to about 500 mg of cetylpyridinium chloride, on a steam bath to one-half of its original volume: the resulting solution meets the requirements of
Identification tests
A,
B, and
C under
Cetylpyridinium Chloride.
Assay—
Transfer a volume of Topical Solution, equivalent to about 150 mg of cetylpyridinium chloride, to a glass-stoppered, 500-mL graduated cylinder, and proceed as directed in the
Assay under
Cetylpyridinium Chloride, beginning with “Add 10 mL of chloroform.” Each mL of 0.02
M sodium tetraphenylboron is equivalent to 7.160 mg of C
21H
38ClN·H
2O.
467
:
meets the requirements.