Propylene Glycol Dilaurate
C27H52O4
Lauric acid, diester with propane-1,2-diol;
Propane-1,2-diyl didodecanoate 440.70
[22788-19-8].
(proe' pi leen glye' kol).
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C27H52O4
Lauric acid, diester with propane-1,2-diol;
Propane-1,2-diyl didodecanoate 440.70
[22788-19-8].DEFINITION
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.
IDENTIFICATION
• A. Thin-Layer Chromatographic Identification Test 
201
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
401:
Meets the requirements
ASSAY
• Procedure
Mobile phase:
Tetrahydrofuran
Sample solution:
200 mg of Propylene Glycol Dilaurate in 5 mL of tetrahydrofuran
Chromatographic system
Mode:
LC
Detector:
Refractive index
Column:
7-mm × 60-cm; 5-µm packing L21 (100
)
)
[Note—Two 7-mm × 30-cm L21 columns may be used in place of one 60-cm column, provided system suitability requirements are met. ]
Temperature
Column:
40
Detector:
40
Flow rate:
1 mL/min
Injection size:
40 µL
System suitability
Sample:
Sample solution
[Note—Elution order: diesters, monoesters, propylene glycol. ]
Suitability requirements
Relative standard deviation:
NMT 1.0% is determined from the monoester peak.
Analysis
Sample:
Sample solution
Calculate the percentage of monoesters or diesters in the portion of Propylene Glycol Dilaurate taken:
Result = (rU/rT) × (100 
D)
D)| rU | = | = peak response for monoesters or diesters |
| rT | = | = sum of the responses of the monoester and diester peaks |
| D | = | = sum of the percentage content of propylene glycol and the percentage content of free fatty acids |
Calculate the percentage content of free fatty acids:
Result = (A/561.1) × 200
| A | = | = acid value |
Acceptance criteria:
NLT 70.0% of diesters and NMT 30.0% of monoesters
IMPURITIES
Inorganic Impurities
• Articles of Botanical Origin, Total Ash 561:
NMT 0.1%
561:
NMT 0.1%
Organic Impurities
• 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.
Analysis
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.
SPECIFIC TESTS
• Fats and Fixed Oils, Acid Value 401:
NMT 4
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.
401:
Propylene Glycol Dilaurate exhibits the following composition profile of fatty acids, determined as directed in the chapter.
| Fatty Acids | Carbon-Chain Length | Percentage (%) |
|---|---|---|
| Caprylic acid | C8 | NMT 0.5 |
| Capric acid | C10 | NMT 2.0 |
| Lauric acid | C12 | NLT 95.0 |
| Myristic acid | C14 | NMT 3.0 |
| Palmitic acid | C16 | NMT 1.0 |
• 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
921:
NMT 1.0%, using a mixture of methanol and methylene chloride (1:1) in place of methanol in the titration vessel
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers, and protect from moisture. No storage requirements are specified.
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Robert H. Lafaver, M.S.
Scientific Liaison 1-301-816-8335 |
(EXC2010) Monographs - Excipients |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 1933
Pharmacopeial Forum: Volume No. 35(3) Page 599