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 90.0percent and not more than 110.0percent 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 preparationcorrespond to those in the chromatograms of the Standard preparation,as obtained in the Assayfor camphor and phenol.
Assay—
Internal standard solution—
Transfer 250mg,accurately weighed,of n-dodecane to a 25-mLvolumetric flask,dilute with chloroform to volume,and mix.
Standard preparation—
Transfer about 96mg of USP Phenol RS,accurately weighed,to a 10-mLvolumetric flask.Add about 224mg of USP Camphor RS,accurately weighed,to the flask.Dilute with chloroform to volume,and mix.Combine 5.0mLof this solution with 5.0mLof Internal standard solutionin a 50-mLvolumetric flask,dilute with chloroform to volume,and mix.
Assay preparation—
Transfer about 1g of Topical Gel,accurately weighed,to a 50-mLflask.Add 5.0mLof Internal standard solution,dilute with chloroform to volume,and mix.
Chromatographic system (see Chromatography á621ñ)—
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 140so that the relative retention times are 0.3for phenol,0.8for camphor,and 1.0for 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 2.0and 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 preparationis not more than 2.0%.
)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 140so that the relative retention times are 0.3for phenol,0.8for camphor,and 1.0for 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 2.0and 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 preparationis not more than 2.0%.
Procedure—
Inject 1to 2µLof the Assay preparationand the Standard preparationinto 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 WRis the weight,in mg,of the appropriate USP Reference Standard in the Standard preparation;Wis the weight of Topical Gel,in mg,taken to prepare the Assay preparation;and rUand rSare the response ratios of the corresponding analyte peaks in the Assay preparationand the Standard preparation,respectively.
Auxiliary Information—
Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 1533
Pharmacopeial Forum:Volume No.29(5)Page 1559
Phone Number:1-301-816-8394