Oleic Acid

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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C₁₈H₃₄O₂ 282.46

9-Octadecenoic acid, (Z)-;

Oleic acid CAS RN®: 112-80-1.

1 DEFINITION

Oleic Acid is manufactured from fats and oils derived from edible sources, animal or vegetable, and consists chiefly of (Z)-9-octadecenoic acid [CH₃(CH₂)₇CH:CH(CH₂)₇COOH]. It contains NLT 65.0% of (Z)-9-octadecenoic acid [CH₃(CH₂)₇CH:CH(CH₂)₇COOH]. It may contain suitable stabilizers.

[Note-Oleic Acid labeled solely for external use is exempt from the requirement that it be prepared from edible sources.]

2 IDENTIFICATION

Change to read:

2.1 A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197F

Sample: Undried specimen

Acceptance criteria: Meets the requirements

2.2 B. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

3.1 Procedure

Standard solution: 1.7 mg/mL of USP Oleic Acid RS in tetrahydrofuran

Sample solution: 1.7 mg/mL of Oleic Acid in tetrahydrofuran

Chromatographic system

• (See Chromatography 〈621〉, System Suitability.)
• Mode: GC
• Detector: Flame ionization
• Column: 0.53-mm × 30-m capillary; 0.25-µm layer of phase G25 (or G35)
• Temperature
• Detector: 280°
• Injection port: 280°
• Column: See Table 1.

Table 1

• Carrier gas: Helium
• Flow rate: 7.0 mL/min
• Injection volume: 1.0 µL
• Injection type: Splitless

System suitability

• Sample: Standard solution
• [Note-The retention time for oleic acid is about 19.2 min.]
• System suitability requirements
• Relative standard deviation: NMT 5.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of oleic acid in the portion of the sample taken:

Result = (rᵤ/rₛ) × (Cₛ/Cᵤ) × 100

rᵤ = peak response for oleic acid from the Sample solution

rₛ = peak response for oleic acid from the Standard solution

Cₛ = concentration of USP Oleic Acid RS in the Standard solution (mg/mL)

Cᵤ = concentration of Oleic Acid in the Sample solution (mg/mL)

Acceptance criteria: NLT 65.0%

4 IMPURITIES

4.1 Residue on Ignition 〈281〉

Sample: 10 mL

Acceptance criteria: NMT 1 mg (about 0.01%)

5 SPECIFIC TESTS

5.1 Content of Fatty Acids

Oleic Acid exhibits the composition profiles of fatty acids shown in Table 2 below, as determined in Fats and Fixed Oils 〈401〉, Fatty Acid Composition.

Table 2

ᵃ The sum of these fatty acids should be NMT 4.0%.

Test solution: Prepare as directed in the chapter, but omitting the initial hydrolysis.

5.2 Congealing Temperature 〈651〉

3°–10° for Oleic Acid derived from animal sources; 10°–16° for Oleic Acid derived from vegetable sources

5.3 Fats and Fixed Oils, Acid Value 〈401〉

196–204, 2 g being used

5.4 Fats and Fixed Oils, Iodine Value 〈401〉

85–105

5.5 Fats and Fixed Oils, Peroxide Value 〈401〉

NMT 10.0

5.6 Water Determination, Method I 〈921〉

NMT 0.4%

5.7 Mineral Acids

Sample: 5 mL

Analysis: Shake the Sample with an equal volume of water at a temperature of about 25° for 2 min, allow the liquids to separate, and pass the water layer through a paper filter previously moistened with water.

Acceptance criteria: The filtrate is not reddened by the addition of 1 drop of methyl orange TS.

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers, protected from light. Store at room temperature, and avoid exposure to excessive heat.

Labeling: If it is for external use only, the labeling so indicates. Label it to indicate whether it is derived from animal or vegetable sources. Indicate the names and quantity of any added stabilizers.

USP Reference Standards 〈11〉

USP Oleic Acid RS