Identification—
The chromatogram of the
Assay preparationobtained as directed in the
Assayexhibits a major peak for tetracycline,the retention time of which corresponds to that exhibited in the chromatogram of the
Standard preparationobtained as directed in the
Assay.
Assay—
Assay preparation—
Transfer an accurately weighed portion of Ointment,equivalent to about 300mg of tetracycline hydrochloride,to a glass-stoppered conical flask,add 20mLof cyclohexane,and shake.Add 35mLof methanol,and sonicate for about 20minutes.Filter this solution into a 100-mLvolumetric flask,and rinse the sides of the conical flask with 40mLof methanol,filtering the rinsing through the filter into the volumetric flask.Dilute with methanol to volume,and mix.Transfer 2.0mLof this solution to a 50-mLvolumetric flask,dilute with Diluting solventto volume,and mix.
Standard preparation—
Dissolve an accurately weighed quantity of
USP Tetracycline Hydrochloride RSquantitatively in methanol to obtain a solution having a known concentration of about 1mg per mL.Transfer 6.0mLof this solution to a 50-mLvolumetric flask,dilute with
Diluting solventto volume,and mix.This solution contains about 0.12mg of
USP Tetracycline Hydrochloride RSper mL.
Procedure—
Proceed as directed in the
Assayunder
Tetracycline Hydrochloride.Calculate the quantity,in mg,of C
22H
24N
2O
8·HCl in the portion of Ointment taken by the formula:
2.5CP(rU/rS),
in which the terms are as defined therein.