Propylene Glycol Dicaprylate/Dicaprate

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

Propylene Glycol Dicaprylate/Dicaprate is a mixture of the propylene glycol mono- and diesters of caprylic acid (C₈H₁₆O₂) and capric acid (C₁₀H₂₀O₂), the diesters fraction being predominant.

2 IDENTIFICATION

Change to read:

A. ▲Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197F▲ (CN 1-May-2020)

B. Thin-Layer Chromatography Identification Test 〈201〉

Standard solution: 50 mg/mL of USP Propylene Glycol Dicaprylate/Dicaprate RS in methylene chloride

Sample solution: 50 mg/mL of Propylene Glycol Dicaprylate/Dicaprate in methylene chloride

Application volume: 10 µL, as streaks

Developing solvent system: Ether and hexane (7:3)

Spray reagent: 0.1 mg/mL of rhodamine 6G in alcohol

Analysis
Samples: Standard solution and Sample solution

Develop the chromatogram over a path of 15 cm, and dry the plate in a current of air. Spray the plate with Spray reagent, and locate the spots on the plate by examination under UV light at a wavelength of 365 nm.

Acceptance criteria: The R values of the principal spots from the Sample solution correspond to those from the Standard solution.

C. It meets the requirements of the test for Fats and Fixed Oils 〈401〉, Fatty Acid Composition.

3 IMPURITIES

Inorganic Impurities

Articles of Botanical Origin, Total Ash 〈561〉: NMT 0.1%

Alkaline Impurities

Sample: 2.0 g of Propylene Glycol Dicaprylate/Dicaprate

Analysis: Dissolve the Sample in a mixture of 1.5 mL of alcohol and 3.0 mL of ether. Add 0.05 mL of bromophenol blue TS.

Acceptance criteria: NMT 0.15 mL of 0.01 N hydrochloric acid is required in order to change the color of the indicator to yellow.

4 SPECIFIC TESTS

Fats and Fixed Oils, Acid Value 〈401〉: NMT 0.2

Fats and Fixed Oils, Fatty Acid Composition 〈401〉: Propylene Glycol Dicaprylate/Dicaprate exhibits the composition profile of fatty acids shown in the following tables:

Fats and Fixed Oils, Hydroxyl Value 〈401〉: NMT 10

Fats and Fixed Oils, Iodine Value 〈401〉: NMT 1.0

Fats and Fixed Oils, Peroxide Value 〈401〉: NMT 1.0

Fats and Fixed Oils, Saponification Value 〈401〉: 320–340

Fats and Fixed Oils, Unsaponifiable Matter 〈401〉: NMT 0.5%, determined on 5.0 g

 Water Determination, Method Ia 〈921〉: NMT 0.1%, using a mixture of methanol and methylene chloride (1:1) in place of methanol in the titration vessel

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers, and protect from moisture. No storage requirements specified.

USP Reference Standards 〈11〉

USP Propylene Glycol Dicaprylate/Dicaprate RS