Propylene Glycol Dilaurate
(proe' pi leen glye' kol).
Lauric acid, diester with propane-1,2-diol;
Propane-1,2-diyl didodecanoate 440.70 [22788-19-8].
Propylene Glycol Dilaurate is a mixture of the propylene glycol mono- and diesters of lauric acid. It contains NLT 70.0% of diesters and NMT 30.0% of monoesters.
• A. Thin-Layer Chromatographic Identification Test 201
Standard solution: 50 mg/mL of USP Propylene Glycol Dilaurate RS in methylene chloride
Sample solution: 50 mg/mL of Propylene Glycol Dilaurate in methylene chloride
Developing solvent system: Hexane and ether (3:7)
Spray reagent: 0.1 mg/mL of rhodamine 6G in alcohol
Analysis: Apply 200 µg of the 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 RF values of the principal spots of the Sample solution correspond to those of the Standard solution.
• B. Fats and Fixed Oils, Fatty Acid Composition 401: Meets the requirements
Mobile phase: Tetrahydrofuran
Sample solution: 200 mg of Propylene Glycol Dilaurate in 5 mL of tetrahydrofuran
Detector: Refractive index
Column: 7-mm × 60-cm; 5-µm packing L21 (100)
[NoteTwo 7-mm × 30-cm L21 columns may be used in place of one 60-cm column, provided system suitability requirements are met. ]
Flow rate: 1 mL/min
Injection size: 40 µL
Sample: Sample solution
[NoteElution order: diesters, monoesters, propylene glycol. ]
Relative standard deviation: NMT 1.0% is determined from the monoester peak.
Sample: Sample solution
Calculate the percentage of monoesters or diesters in the portion of Propylene Glycol Dilaurate taken:
Result = (rU/rT) × (100 D)
Calculate the percentage content of free fatty acids:
Result = (A/561.1) × 200
Acceptance criteria: NLT 70.0% of diesters and NMT 30.0% of monoesters
• Articles of Botanical Origin, Total Ash 561: NMT 0.1%
• Procedure: Limit of Propylene Glycol
Mobile phase: Proceed as directed in the Assay.
Standard stock solution: 4 mg/mL of USP Propylene Glycol RS in tetrahydrofuran
Standard solutions: Into four 15-mL flasks, introduce respectively 0.25, 0.5, 1.0, and 2.5 mL of Standard stock solution, and dilute with tetrahydrofuran to 5.0 mL. In a fifth 15-mL flask, introduce 5.0 mL of Standard stock solution.
Sample solution: Use the Sample solution from the Assay.
Chromatographic system: Proceed as directed in the Assay.
Samples: Standard solutions and Sample solution
Prepare a standard curve of peak area versus concentration, in mg/mL, of propylene glycol in the Standard solutions. Obtain the concentration, C, in mg/mL, of propylene glycol in the Sample solution from the standard curve.
Acceptance criteria: NMT 2.0% of propylene glycol is found.
• Fats and Fixed Oils, Acid Value 401: NMT 4
• Fats and Fixed Oils, Fatty Acid Composition 401: Propylene Glycol Dilaurate exhibits the following composition profile of fatty acids, determined as directed in the chapter.
• Water Determination, Method Ia 921: NMT 1.0%, using a mixture of methanol and methylene chloride (1:1) in place of methanol in the titration vessel
• Packaging and Storage: Preserve in well-closed containers, and protect from moisture. No storage requirements are specified.
• USP Reference Standards 11
USP Propylene Glycol Dilaurate RS
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USP35NF30 Page 1933Pharmacopeial Forum: Volume No. 35(3) Page 599