Hydrogenated Lanolin

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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CAS RN^®: 8031-44-5.

1 DEFINITION

A mixture of higher aliphatic alcohols, hydrocarbons, and sterols is obtained from the direct high-pressure, high-temperature hydrogenation of lanolin. During the hydrogenation process, the esters and acids present are reduced to the corresponding alcohols. Alcoholic derivatives may be further reduced to hydrocarbons. It may contain antioxidants.

2 IDENTIFICATION

2.1 A.

Sample: 50 mg

Analysis: Dissolve the Sample in 5 mL of methylene chloride, and add 1 mL of acetic anhydride and 0.1 mL of sulfuric acid.

Acceptance criteria: A green color is produced.

2.2 B. CHROMATOGRAPHIC IDENTITY

Analysis: Proceed as directed in the test for Chromatographic Profile of Fatty Alcohols, Hydrocarbons, and Sterols in the Assay.

Acceptance criteria: The retention times of the cetyl alcohol, stearyl alcohol, cholestane, cholestanol, and 24,25-dihydrolanosterol peaks of the Sample solution correspond to those of Standard solution A, as obtained in the Assay.

3 ASSAY

3.1 CHROMATOGRAPHIC PROFILE OF FATTY ALCOHOLS, HYDROCARBONS, AND STEROLS

Standard solution A: 2.5 mg/mL of USP Hydrogenated Lanolin RS in dehydrated alcohol

Standard solution B: 0.5 mg/mL of cholestane, 0.5 mg/mL of cholestanol, and 0.25 mg/mL of 24,25-dihydrolanosterol in dehydrated alcohol

Standard solution C: 0.5 mg/mL of USP Cetyl Alcohol RS in dehydrated alcohol. [Note-Vortex or sonication helps standard preparation.]

Standard solution D: 0.5 mg/mL of USP Stearyl Alcohol RS in dehydrated alcohol. [Note-Vortex or sonication helps standard preparation.]

Sample solution: 2.5 mg/mL of Hydrogenated Lanolin in dehydrated alcohol

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.25-mm × 30-m fused-silica capillary; 0.25-µm layer of phase G2

Temperatures

Detector: 350°

Injection port: 325°

Column: See Table 1.

Carrier gas: Helium

Flow rate: 1 mL/min

Injection volume: 1 µL

System suitability

Samples: Standard solution A, Standard solution B, Standard solution C, and Standard solution D

[Note-See Table 2 for relative retention times.]

Table 2

System suitability requirements

Resolution: NLT 30 between cetyl alcohol and stearyl alcohol, Standard solution A

Analysis

Samples: Standard solution A, Standard solution B, Standard solution C, Standard solution D, and Sample solution

Identify the peaks from Standard solution A, Standard solution B, Standard solution C, and Standard solution D.

Calculate the percentage of cetyl alcohol (stearyl alcohol, cholestane, cholestanol, or 24,25-dihydrolanosterol) in the portion of Hydrogenated Lanolin taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of cetyl alcohol (stearyl alcohol, cholestane, cholestanol, or 24,25-dihydrolanosterol) from the Sample solution

r_S = peak response of cetyl alcohol (stearyl alcohol, cholestane, cholestanol, or 24,25-dihydrolanosterol) from Standard solution C, Standard solution D, or Standard solution B

C_S = concentration of USP Cetyl Alcohol RS (USP Stearyl Alcohol RS, cholestane, cholestanol, or 24,25-dihydrolanosterol) in Standard solution C, Standard solution D, or Standard solution B (mg/mL)

C_U = concentration of Hydrogenated Lanolin in the Sample solution (mg/mL)

Acceptance criteria

Sample solution: Chromatogram exhibits a profile similar to that in the chromatogram of Standard solution A.

Cetyl alcohol, stearyl alcohol, cholestane, cholestanol, and 24,25-dihydrolanosterol: See Table 3.

4 IMPURITIES

RESIDUE ON IGNITION (281): NMT 0.1%, determined on 5.0 g

5 SPECIFIC TESTS

MELTING RANGE OR TEMPERATURE (741): 45°-55°. Allow to stand at 20° for 16 h.

FATS AND FIXED OILS, Acid Value (401): NMT 1.0, determined on 5.0 g

FATS AND FIXED OILS, Hydroxyl Value (401): 140-180

FATS AND FIXED OILS, Saponification Value (401): NMT 8.0. Heat under reflux for 4 h.

LOSS ON DRYING (731)

Sample: 2.0 g

Analysis: Dry the Sample in an oven at 105° for 1 h.

Acceptance criteria: NMT 3.0%

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in well-closed containers, protected from light. Do not store above 45°.

LABELING: Label it to indicate the name and amount of the antioxidant added.

USP REFERENCE STANDARDS (11)

USP Cetyl Alcohol RS

USP Hydrogenated Lanolin RS

USP Stearyl Alcohol RS