Camphorated Phenol Topical Gel
» Camphorated Phenol Topical Gel is a mixture of camphor and phenol in a suitable gel vehicle. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of camphor (C10H16O) and phenol (C6H6O).
Packaging and storage— Preserve in tight containers. Store at room temperature, avoid excessive heat, and close cover after each use.
Identification— The retention times of the camphor and phenol peaks in the chromatograms of the Assay preparation correspond to those in the chromatograms of the Standard preparation, as obtained in the Assay for camphor and phenol.
Internal standard solution— Transfer 250 mg, accurately weighed, of n-dodecane to a 25-mL volumetric flask, dilute with chloroform to volume, and mix.
Standard preparation— Transfer about 96 mg of USP Phenol RS, accurately weighed, to a 10-mL volumetric flask. Add about 224 mg of USP Camphor RS, accurately weighed, to the flask. Dilute with chloroform to volume, and mix. Combine 5.0 mL of this solution with 5.0 mL of Internal standard solution in a 50-mL volumetric flask, dilute with chloroform to volume, and mix.
Assay preparation— Transfer about 1 g of Topical Gel, accurately weighed, to a 50-mL flask. Add 5.0 mL of Internal standard solution, dilute with chloroform to volume, and mix.
Chromatographic system (see Chromatography 621)— The gas chromatograph is equipped with a flame-ionization detector (200) and a 2-mm × 1.8-m glass column packed with 100- to 120-mesh S1A, coated with 15% G44. The carrier gas is helium. Adjust the column temperature to about 140 so that the relative retention times are 0.3 for phenol, 0.8 for camphor, and 1.0 for the internal standard. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the resolution, R, between the camphor peak and the internal standard peak is not less than 2.0 and between the phenol peak and the camphor peak is not less than 5.0; and the relative standard deviation of the peak response ratio of the camphor peak and phenol peak to the internal standard peak for five consecutive injections of the Standard preparation is not more than 2.0%.
Procedure— Inject 1 to 2 µL of the Assay preparation and the Standard preparation into the gas chromatograph, record the chromatograms, and determine the peak response ratios. Calculate the percentage of camphor (w/w) and the percentage of phenol (w/w) in the sample according to the formula:
(50WR / W)(rU / rS)
in which WR is the weight, in mg, of the appropriate USP Reference Standard in the Standard preparation; W is the weight of Topical Gel, in mg, taken to prepare the Assay preparation; and rU and rS are the response ratios of the corresponding analyte peaks in the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Behnam Davani, Ph.D., M.B.A.
Senior Scientist
(MDAA05) Monograph Development-Antivirals and Antimicrobials
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 3273
Pharmacopeial Forum: Volume No. 29(5) Page 1559
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.