Glyceryl Monostearate
Octadecanoic acid, monoester with 1,2,3-propanetriol;
Monostearin
[31566-31-1].
(glis' er il mon'' oh steer' ate).
Octadecanoic acid, monoester with 1,2,3-propanetriol;
Monostearin
[31566-31-1].DEFINITION
Glyceryl Monostearate contains NLT 90.0% of monoglycerides of saturated fatty acids, chiefly glyceryl monostearate (C21H42O4) and glyceryl monopalmitate (C19H38O4). It may contain a suitable antioxidant.
ASSAY
• Procedure
Mobile phase:
Tetrahydrofuran
Sample solution:
8 mg/mL of Glyceryl Monostearate in tetrahydrofuran
Chromatographic system
Mode:
LC
Detector:
Refractive index
Column:
7.5-mm × 60-cm; 5-µm 100-
packing L21
packing L21
Temperature:
Column and detector temperatures are maintained at 40
.
.
[Note—Two or three 7.5-mm × 30-cm L21 columns may be used in place of the one 60-cm column, provided that 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. ]
provides stable separation conditions and ensures better sample solubility. ]
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 0.77, 0.81, 0.86, and 1.0, respectively. ]
Suitability requirements
Relative standard deviation:
NMT 2.0%, determined from the monoglycerides peak
Analysis
Sample:
Sample solution
Calculate the percentage of monoglycerides in the portion of Glyceryl Monostearate taken:
Result = (rU/rT) × 100
| rU | = | = peak response of the monoglycerides |
| rT | = | = sum of all the glyceride peak responses |
Acceptance criteria:
NLT 90.0% of monoglycerides of saturated fatty acids, chiefly C21H42O4 and C19H38O4
IMPURITIES
Organic Impurities
• Procedure: Limit of Free Glycerin
Propionating reagent:
Pyridine and propionic anhydride (1:2)
Internal standard solution:
0.2 mg/mL of tributyrin in chloroform
Standard solution:
Transfer 15 mg of glycerin and 50 mg of tributyrin to a glass-stoppered, 25-mL conical flask. Add 3 mL of Propionating reagent, and heat at 75 for 30 min. Volatilize the reagents with the aid of a stream of nitrogen at room temperature, and add 12 mL of chloroform. Dilute 1 mL of this mixture with chloroform to 20 mL.
for 30 min. Volatilize the reagents with the aid of a stream of nitrogen at room temperature, and add 12 mL of chloroform. Dilute 1 mL of this mixture with chloroform to 20 mL.
Sample solution:
Transfer 50 mg of Glyceryl Monostearate to a glass-stoppered, 25-mL conical flask. Add 5 mL of Internal standard solution by pipet, and mix to dissolve. Immerse the flask in a water bath, maintained at a temperature between 45 and 50, and volatilize the chloroform with the aid of a stream of nitrogen. Add 3 mL of Propionating reagent, and heat at 75 for 30 min. Volatilize the reagents with the aid of a stream of nitrogen at room temperature, and add 5 mL of chloroform.
and 50, and volatilize the chloroform with the aid of a stream of nitrogen. Add 3 mL of Propionating reagent, and heat at 75 for 30 min. Volatilize the reagents with the aid of a stream of nitrogen at room temperature, and add 5 mL of chloroform.
Chromatographic system
Mode:
GC
Detector:
Flame ionization (under typical conditions)
Column:
4-mm × 2.4-m borosilicate glass, packed with 2% liquid phase G16, on 80- to 100-mesh support S1A
Temperature
Injector:
300
Detector:
310
Column:
The column is maintained isothermally at a temperature between 190 and 200.
and 200.
Carrier gas:
Helium
Flow rate:
70 mL/min
System suitability
Sample:
Standard solution (6–10 injections)
Suitability requirements
Resolution:
NLT 4.0 between derivatized glycerin and tributyrin
Relative standard deviation:
NMT 2.0% of the ratio of their peak areas
Analysis
Samples:
Standard solution and Sample solution
Calculate the response factor, F:
F = (AD/AS) × (WS/WD)
| AD | = | = peak area of tributyrin from the Standard solution |
| AS | = | = peak area of tripropionin from the Standard solution |
| WS | = | = weight of glycerin in the Standard solution (mg) |
| WD | = | = weight of tributyrin in the Standard solution (mg) |
Calculate the percentage of glycerin in the portion of Glyceryl Monostearate taken:
Result = (AU/AS) × (WD/WU) × F × 100
| AU | = | = peak area of tripropionin in the Sample solution |
| AS | = | = peak area of tributyrin in the Sample solution |
| WD | = | = weight of tributyrin in 5 mL of Internal standard solution (mg) |
| WU | = | = weight of Glyceryl Monostearate in the Sample solution (mg) |
Acceptance criteria:
NMT 1.2%
SPECIFIC TESTS
• Melting Range or Temperature, Class I 
741
:
Does not melt below 55
741:
Does not melt below 55
• Fats and Fixed Oils, Acid Value 401:
NMT 6
401:
NMT 6
• Fats and Fixed Oils, Hydroxyl Value 401:
290–330
401:
290–330
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight, light-resistant containers.
• Labeling:
Label it to indicate the name and quantity of any added antioxidant.
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 |
USP35–NF30 Page 1815
Pharmacopeial Forum: Volume No. 31(6) Page 1669