Lanolin Alcohols

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

Lanolin Alcohols is a mixture of aliphatic alcohols, triterpenoid alcohols, and sterols, obtained by the hydrolysis of Lanolin. It may contain NMT 0.1% of a suitable antioxidant.

2 IDENTIFICATION

A.

Sample: 0.5 g

Analysis: Dissolve the Sample in 5 mL of chloroform, and add 1 mL of acetic anhydride and 2 drops of sulfuric acid.

Acceptance criteria: A green color is produced.

3 ASSAY

Content of Sterols (as cholesterol)

Sample: 20 g

Analysis: Melt the Sample on a water bath, mix, and allow to cool. Dissolve 100 mg in 12 mL of warm (60°) 90% alcohol. Allow to stand for 18h, pass through a medium-porosity, sintered-glass filter, and wash the residue with two 15-mL portions of 90% alcohol. Combine the filtrate and washings, add 20 mL of a freshly prepared 1-in-100 solution of digitonin in 90% alcohol, and warm to 60°. Allow to cool, pass through a medium-porosity, sintered-glass filter with the aid of gentle vacuum, wash the residue with 10 mL of 90% alcohol, and dry at 105° to constant weight. Each g of residue is equivalent to 0.239 g of cholesterol.

Acceptance criteria: NLT 30.0% of sterols, calculated as cholesterol

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.15%

Copper

Solution A: 1 mg/mL of sodium diethyldithiocarbamate

Sample: 5.0 g

Control: Add 1 mL of Solution A and a few drops of 6 N ammonium hydroxide to 2.5 mL of a 39.3-ppm solution of cupric sulfate. Dilute with water to 50 mL.

Analysis: Heat the Sample over a small flame until charred, ignite the residue at 550°, and dissolve the ash in 5 mL of hydrochloric acid, with the aid of heat. Cool, dilute with water, render alkaline with ammonium hydroxide, boil to remove the excess ammonia, add a few drops of bromine TS, boil again, and filter. To the filtrate add 1 mL of Solution A, a few drops of 6 N ammonium hydroxide, and suficient water to bring the volume to 50 mL.

Acceptance criteria: The Sample is not darker than the Control (5 ppm).

5 SPECIFIC TESTS

Melting Range or Temperature, Class II 〈741〉: NLT 56°

Acidity and Alkalinity

Analysis: Boil 10 g with 100 mL of water for 5 min, with frequent stirring. Remove the source of heat, add 0.5 mL of phenolphthalein TS, and stir.

Acceptance criteria: No pink color is produced. Add 0.5 mL of methyl orange TS, and stir: no red color is produced.

Loss on Drying 〈731〉

Analysis: Dry at 105° for 1 h.

Acceptance criteria: NMT 0.5%

6 OFFICIAL

Fats and Fixed Oils, Acid Value 〈401〉: NMT 2.0.

Fats and Fixed Oils, Hydroxyl Value 〈401〉: 120–180

Fats and Fixed Oils, Peroxide Value 〈401〉

Sample: Take wedge-shaped pieces with bases that contain part of the surface.

Analysis: Melt the pieces before carrying out the determination. Before adding the 0.5 mL of saturated potassium iodide solution, cool the solution obtained to room temperature.

Acceptance criteria: NMT 15

Fats and Fixed Oils, Saponification Value 〈401〉

Sample: 5 g of molten Lanolin Alcohols

Analysis: Reflux the Sample with the alcoholic potassium hydroxide for 4 h.

Acceptance criteria: NMT 12

7 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed, light-resistant containers, and store at controlled room temperature.

Labeling: Label it to indicate the name and quantity of any antioxidant added.