Glyceryl Monooleate

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

Glyceryl Monooleate is a mixture of monoglycerides, mainly glyceryl monooleate, together with variable quantities of diglycerides and triglycerides. It is obtained by partial glycerolysis of vegetable oil that consists mainly of triglycerides of oleic acid, or by esterification of Glycerol with oleic acid of vegetable or animal origin. It is defined by the nominal content of monoglycerides. The assay requirements differ as set forth in the accompanying table. A suitable antioxidant may be added.

Nominal Content of Monoglycerides (%)

2 IDENTIFICATION

A. Thin-Layer Chromatographic Identification Test 〈201〉

Standard solution: 50 mg/mL of USP Glyceryl Monooleate 40% RS or USP Glyceryl Monooleate 90% RS in methylene chloride

Sample solution: 50 mg/mL of Glyceryl Monooleate in methylene chloride

Application volume: 10 µL

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

Spray reagent: 0.1 mg/mL of rhodamine B in alcohol

Analysis: Proceed as directed in the chapter. Spray with the Spray reagent, and locate the spots on the plate by examination under UV light at a wavelength of 365 nm.

Acceptance criteria: The principal spot of the Sample solution corresponds in color, size, and R value to that of the Standard solution.

B. It meets the requirements in Specific Tests for Fats and Fixed Oils, Iodine Value 〈401〉.

3 ASSAY

Procedure:

Mobile phase: Tetrahydrofuran

Sample solution: 40 mg/mL of Glyceryl Monooleate in tetrahydrofuran

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: Refractive index

Column: 7.5-mm × 60-cm; 5-µm 100-Å packing L21

[Note—Two or three 7.5-mm × 30-cm L21 columns may be used in place of the one 60-cm column, provided that the system suitability requirements are met. The column temperature may be lowered to ambient temperature, although working at 40° provides stable separation conditions and ensures better sample solubility.]

Temperature:

Column: 40°

Detector: 40°

Flow rate: 1 mL/min

Injection size: 40 µL

System suitability

Sample: Sample solution

[Note—The relative retention times for triglycerides, diglycerides, monoglycerides, and Glycerin are about 0.76, 0.79, 0.85, and 1.0, respectively.]

Suitability requirements:

Resolution: NLT 1.0 between the diglycerides and monoglycerides

Relative standard deviation: NMT 2.0%, determined from the monoglycerides peak

Analysis:

Sample: Sample solution

Calculate the percentage of monoglycerides, diglycerides, and triglycerides in the portion of Glyceryl Monooleate taken:

Result = (r_U /r_T ) × 100

r_U = individual peak responses for the monoglycerides, diglycerides, and triglycerides, as appropriate

r_T = sum of all the glyceride peak responses

Acceptance criteria: See the table in the Definition.

4 IMPURITIES

Limit of Free Glycerin

Mobile phase, Sample solution, and Chromatographic system: Proceed as directed in the Assay.

Standard solutions: Prepare four solutions by dissolving glycerin in tetrahydrofuran, and diluting each with tetrahydrofuran as necessary, to obtain solutions having known concentrations of 0.4, 1.0, 2.0, and 4.0 mg/mL.

Standard curve

Samples: Standard solutions

Plot: Record the chromatograms, and measure the responses for the glycerin peaks. Plot the glycerin peak responses obtained versus the concentration, in mg/mL, of glycerin in the Standard solutions.

Analysis:

Sample: Sample solution

From the Standard curve, determine the glycerin concentration, in mg/mL, in the Sample solution.

Calculate the percentage of free glycerin in the portion of Glyceryl Monooleate taken:

Result = (Cₛ / Cₜ) × 100

Cₛ = concentration of glycerin in the Sample solution from the Standard curve (mg/mL)

Cₜ = concentration of Glyceryl Monooleate in the Sample solution (mg/mL)

Acceptance criteria: NMT 6.0%

5 SPECIFIC TESTS

Fats and Fixed Oils, Acid Value 〈401〉: NMT 6.0, determined on 1.0 g

Fats and Fixed Oils, Iodine Value 〈401〉: 65.0–95.0

Fats and Fixed Oils, Peroxide Value 〈401〉: NMT 12.0, determined on 2.0 g

Fats and Fixed Oils, Saponification Value 〈401〉: 150–175, determined on 2.0 g

Fats and Fixed Oils, Fatty Acid Composition 〈401〉: Glyceryl Monooleate exhibits the following composition profile of fatty acids (see Table 1), determined as directed in the chapter.

Water Determination, Method I 〈921〉: NMT 1.0%, using a mixture of methanol and methylene chloride (1:1) in place of methanol in the titration vessel

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

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers. No storage requirements specified.

Labeling: The labeling indicates the nominal content of monoglycerides and the name and the concentration of any added antioxidant.

USP Reference Standards 〈11〉

USP Glyceryl Monooleate 40% RS

USP Glyceryl Monooleate 90% RS