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Octadecanoic acid, monoester with 1,2,3-propanetriol;
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.
Mobile phase: Tetrahydrofuran
Sample solution: 8 mg/mL of Glyceryl Monostearate in tetrahydrofuran
Detector: Refractive index
Column: 7.5-mm × 60-cm; 5-µm 100- packing L21
Temperature: Column and detector temperatures are maintained at 40.
[NoteTwo 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. ]
Flow rate: 1 mL/min
Injection size: 40 µL
Sample: Sample solution
[NoteThe relative retention times for triglycerides, diglycerides, monoglycerides, and glycerin are 0.77, 0.81, 0.86, and 1.0, respectively. ]
Relative standard deviation: NMT 2.0%, determined from the monoglycerides peak
Sample: Sample solution
Calculate the percentage of monoglycerides in the portion of Glyceryl Monostearate taken:
Result = (rU/rT) × 100
Acceptance criteria: NLT 90.0% of monoglycerides of saturated fatty acids, chiefly C21H42O4 and C19H38O4
• 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.
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.
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
Column: The column is maintained isothermally at a temperature between 190 and 200.
Carrier gas: Helium
Flow rate: 70 mL/min
Sample: Standard solution (610 injections)
Resolution: NLT 4.0 between derivatized glycerin and tributyrin
Relative standard deviation: NMT 2.0% of the ratio of their peak areas
Samples: Standard solution and Sample solution
Calculate the response factor, F:
F = (AD/AS) × (WS/WD)
Calculate the percentage of glycerin in the portion of Glyceryl Monostearate taken:
Result = (AU/AS) × (WD/WU) × F × 100
Acceptance criteria: NMT 1.2%
• Melting Range or Temperature, Class I 741: Does not melt below 55
• Fats and Fixed Oils, Acid Value 401: NMT 6
• Fats and Fixed Oils, Hydroxyl Value 401: 290330
• Packaging and Storage: Preserve in tight, light-resistant containers.
• Labeling: Label it to indicate the name and quantity of any added antioxidant.