Undecylenic 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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C₁₁H₂₀O₂    184.28

10-Undecenoic acid;

Undec-10-enoic acid CAS RN: 112-38-9; UNII: K3D86KJ24N.

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1 DEFINITION

Undecylenic Acid contains NLT 97.0% and NMT102.0% _{(USP 1-Aug-2022)} of undecylenic acid (C₁₁H₂₀O₂).

2 IDENTIFICATION

Delete the following:

Sample: 1 mL of Undecylenic Acid

Analysis: To the Sample add potassium permanganate TS dropwise.

Acceptance criteria: The permanganate color is discharged. _{(USP 1-Aug-2022)}

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A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197A or 197F _{(USP 1-Aug-2022)}

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B. The retention time of the undecylenic acid peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay _{(USP 1-Aug-2022)}

3 ASSAY

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PROCEDURE

Undecyle Standard solution: 0.5 mg/mL of USP Undecylenic Acid RS in n-heptane

Sample solution: 0.5 mg/mL of Undecylenic Acid in n-heptane

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.25-mm × 30-m fused-silica capillary; coated with a 0.25-μm lm of phase G35

Temperatures

Injection port: 280°

Detector: 350*

Column: See Table 1.

Table 1

Carrier gas: Helium

Flow rate: 0.7 mL/min

Injection volume: 1 μL

Injection type: Split, split ratio 25:1

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 1.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of undecylenic acid (C₁₁H₂₀O₂) in the portion of Undecylenic Acid taken:

Result = (r_u /r_s ) × (C_s /C_u ) × 100

r_u = peak response of undecylenic acid from the Sample solution

r_s = peak response of undecylenic acid from the Standard solution

C_s = concentration of USP Undecylenic Acid RS in the Standard solution (mg/mL)

C_u = concentration of Undecylenic Acid in the Sample solution (mg/mL) _{(USP 1-Aug-2022)}

Acceptance criteria: 97.0%–102.0% _{(USP 1-Aug-2022)}

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.15%

Water-Soluble Acids

Sample: 5 mL of Undecylenic Acid

Titrimetric system

Mode: Direct titration

Titrant: 0.01 N sodium hydroxide VS

Endpoint detection: Visual

Analysis: Shake the Sample with 5 mL of water and lter the water layer through a lter paper previously moistened with water. Add 1 drop of

methyl orange TS, and titrate with Titrant.

Acceptance criteria: NMT 1.0 mL of Titrant is required to match the color produced by 1 drop of methyl orange TS in 5 mL of water.

5 SPECIFIC TESTS

Specific Gravity 〈841〉: 0.910–0.913

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Congealing Temperature 〈651〉: NLT 21° _{(USP 1-Aug-2022)}

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Refractive Index 〈831〉: 1.447–1.448 _{(USP 1-Aug-2022)}

Fats and Fixed Oils 〈401〉, Procedures, Iodine Value: 131–138

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers.

Add the following:

USP Reference Standards 〈11〉

USP Undecylenic Acid RS _{(USP 1-Aug-2022)}