Glyceryl Tricaprylate

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 Tricaprylate contains NLT 90.0% of triglycerides of saturated fatty acids, chiefly glyceryl tricaprylate (C₂₇H₅₀O₆).

2 IDENTIFICATION

2.1 A. FATTY ACID COMPOSITION

Boron trifluoride methanol solution: 140 mg/mL of boron trifluoride in methanol

Saturated sodium chloride solution: Mix 1 part of sodium chloride with 2 parts of water, shake intermittently, and allow to stand. Before use, decant the solution from any undissolved substance and filter, if necessary.

Standard solution 1: 1.0 mg/mL of USP Methyl Caproate RS, 1.0 mg/mL of USP Methyl Caprylate RS, and 2.0 mg/mL of USP Methyl Caprate RS in n-heptane

Standard solution 2: 0.1 mg/mL of USP Methyl Caproate RS, 0.1 mg/mL of USP Methyl Caprylate RS, and 0.2 mg/mL of USP Methyl Caprate RS in n-heptane, diluted from Standard solution 1

Standard solution 3: Prepare an ester mixture by mixing a commercially available ester mixture with methyl caprylate and methyl caprate, or prepare an ester mixture by using USP Methyl Caproate RS, USP Methyl Caprylate RS, USP Methyl Caprate RS, and USP Methyl Laurate RS. Dissolve a quantity of the prepared ester mixture containing methyl caproate, methyl caprylate, methyl caprate, and methyl laurate in n- heptane to make a solution of about 9.0 mg/mL for methyl caprylate, 0.5 mg/mL for methyl caprate, and 0.1 mg/mL for each of methyl caproate and methyl laurate.

Sample solution: Transfer 100 mg of Glyceryl Tricaprylate to a 25-mL conical flask fitted with a suitable water-cooled reflux condenser and a magnetic stir bar. Add 2 mL of a 20-mg/mL solution of sodium hydroxide in methanol, mix, and reflux for about 30 min. Add 2 mL of Boron trifluoride methanol solution through the condenser and reflux for about 30 min. Add 4 mL of n-heptane through the condenser and reflux for 5 min. Cool, remove the condenser, add about 10 mL of Saturated sodium chloride solution, shake, add a quantity of Saturated sodium chloride solution to bring the upper layer up to the neck of the flask, and allow the layers to separate. Collect 2 mL of the n-heptane layer (upper layer); wash with three quantities of water, 2 mL each; and dry the n-heptane phase over anhy drous sodium sulfate.

2.1.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.) Mode: GC

Detector: Flame ionization

Column: 0.53-mm × 30-m capillary bonded with a 1.0-µm layer of phase G16

Temperatures

Injection port: 250°

Detector: 250° Column: See Table 1.

Carrier gas: Helium Flow rate: 10 mL/min Injection volume: 2 µL

Injection type: Split ratio, 4:1

2.1.2 System suitability

Samples: Standard solution 1 and Standard solution 2

[NOTE—The relative retention times for methyl caproate, methyl caprylate, and methyl caprate are about 0.7, 1.0, and 1.4, respectively.]

Suitability requirements

Resolution: NLT 4.0 between the methyl caprylate and methyl caprate peaks, Standard solution 1

Signal-to-noise ratio: NLT 10 for the methyl caproate peak, Standard solution 2

2.1.3 Analysis

Samples: Standard solution 3 and Sample solution

Measure the peak areas of the methyl esters of the fatty acids. Disregard any peaks with an area less than 0.05% of the total area and any peak due to the solvent. [NOTE—Relative retention times for several methyl esters are summarized in Table 2.]

2.2 B. CONTENT OF TRIGLYCERIDES

Analysis: Proceed as directed in the test for Content of Triglycerides in the Assay. Acceptance criteria: NLT 90.0% of triglycerides

2.3 C. FATS AND FIXED OILS 〈401〉

Procedures, Saponification Value: 340–370

3 ASSAY

Change to read:

CONTENT OF TRIGLYCERIDES

System suitability solution: 20 ▲mg/mL▲ (ERR 1-Oct-2018) each of 1-monooctanoyl-rac-gly cerol and 1-monodecanoyl-rac-gly cerol in tetrahydrofuran

Standard solution 1: 50 mg/mL of USP Gly ceryl Monocaprylate RS in tetrahy drofuran

Standard solution 2: 50 mg/mL of USP Glyceryl Tricaprylate RS in tetrahydrofuran Sample solution: 50 mg/mL of Glyceryl Tricaprylate in tetrahy drofuran Chromatographic system

(See Chromatography 〈621〉, System Suitability.) Mode: GC

Detector: Flame ionization

Column: 0.32-mm × 10-m bonded with a 0.1-µm layer of phase G27 Temperatures

Injection port: 350°

Detector: 370° Column: See Table 4.