Camphorated Phenol Topical Gel

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Camphorated Phenol Topical Gel is a mixture of Camphor and Phenol in a suitable gel vehicle. It contains NLT 90.0% and NMT 110.0% of the labeled amount of camphor (C₁₀H₁₆O) and phenol (C₆H₆O).

2 IDENTIFICATION

A. The retention times of the camphor and phenol peaks of the Sample solution correspond to those of the Standard solution, as obtained in the Assay.

3 ASSAY

PROCEDURE

Internal standard solution: 10 mg/mL of n-dodecane in chloroform

Standard stock solution: 9.6 mg/mL of USP Phenol RS and 22.4 mg/mL of USP Camphor RS, in chloroform

Standard solution: 0.96 mg/mL of USP Phenol RS, 2.24 mg/mL of USP Camphor RS, and 1 mg/mL of n-docecane in chloroform from

Standard stock solution and Internal standard solution

Sample solution: Transfer 1 g of Topical Gel to a 50-mL flask. Add 5.0 mL of Internal standard solution, and dilute with chloroform to volume.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 2-mm x 1.8-m glass; packed with 100- to 120-mesh S1A, coated with 15% G44

Carrier gas: Helium

Temperatures

Detector: 200°

Column: 140°

Injection volume: 1-2 µL

System suitability

Sample: Standard solution

[NOTE-The relative retention times are 0.3 for phenol, 0.8 for camphor, and 1.0 for the internal standard.]

Suitability requirements

Resolution: NLT 2.0 between camphor and the internal standard, and NLT 5.0 between phenol and camphor

Relative standard deviation: NMT 2.0% of the peak response ratio of camphor and phenol to the internal standard for five consecutive injections

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of camphor (w/w) and phenol (w/w) in the portion of Topical Gel taken:

Result = (R_u/R_s) × (C_s/C_u) × 100

R_u = peak response ratio of the corresponding analyte to the internal standard from the Sample solution

R_s = peak response ratio of the corresponding analyte to the internal standard from the Standard solution

C_s = concentration of the appropriate USP Reference Standard in the Standard solution (mg/mL)

C_u = nominal concentration of the appropriate analyte in the Sample solution (mg/mL)

Acceptance criteria: 90.0%-110.0%

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers. Store at room temperature, avoid excessive heat, and close the cover after each use.

USP Reference Standards 〈11〉

USP Camphor RS

USP Phenol RS