» Glyceryl Monolinoleate is a mixture of monoglycerides, mainly glyceryl monooleate and glyceryl monolinoleate, together with variable quantities of diglycerides and triglycerides. It is obtained by partial glycerolysis of vegetable oil that consists mainly of triglycerides of linoleic acid. It contains not less than 32.0 percent and not more than 52.0 percent of monoglycerides, not less than 40.0 percent and not more than 55.0 percent of diglycerides, and not less than 5.0 percent and not more than 20.0 percent of triglycerides. A suitable antioxidant may be added.
Packaging and storage Preserve in tight containers. No storage requirements specified.
Labeling The labeling indicates the name and the concentration of any added antioxidant.
A: Thin-Layer Chromatographic Identification Test 201
Test solution: a solution in methylene chloride containing 0.05 g per mL.
Developing solvent: a mixture of ether and hexane (70:30).
Spray reagent: a solution containing 0.02 g of rhodamine B in 0.2 L of alcohol.
Procedure Proceed as directed in the chapter. Spray with the Spray reagent, and locate the spots on the plate by examination under UV light at a wavelength of 365 nm: the principal spot obtained from the Test solution corresponds in color, size, and RF value to that obtained from the Standard solution.
B: It meets the requirements of the test for Iodine value.
C: It meets the requirements of the test for Fatty acid composition.
Acid value 401: not more than 6.0, determined on 1.0 g.
Iodine value 401: between 100 and 140.
Peroxide value 401: not more than 12.0, determined on 2.0 g.
Saponification value 401: between 160 and 180, determined on 2.0 g.
Fatty acid composition 401 Glyceryl Monolinoleate exhibits the following composition profile of fatty acids, as determined in the section Fatty Acid Composition:
Water, Method I 921: not more than 1.0%, using a mixture of methanol and methylene chloride (1:1, v/v) in place of methanol in the titration vessel.
Total ash 561: not more than 0.1%.
Limit of free glycerin
Mobile phase and Chromatographic system Proceed as directed in the Assay.
Standard solutions Prepare four solutions by dissolving accurately weighed quantities of glycerin in tetrahydrofuran and by diluting each with tetrahydrofuran, as necessary, to obtain solutions having known concentrations of about 0.4, 1.0, 2.0, and 4.0 mg per mL.
Test solution Use the Assay preparation, prepared as directed in the Assay.
Procedure Separately inject equal volumes (about 40 µL) of the Standard solutions and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the glycerin peaks. Plot the glycerin peak responses obtained versus the concentration, in mg per mL, of glycerin in the Standard solutions. From the standard curve so obtained, determine the glycerin concentration, C, in mg per mL, in the Test solution. Calculate the percentage of free glycerin in the portion of Glyceryl Monolinoleate taken by the formula:
500(C/W)in which C is as obtained above; and W is the amount, in mg, of Glyceryl Monolinoleate taken to prepare the Test solution: not more than 6.0% of free glycerin is found.
Mobile phase: tetrahydrofuran.
Assay preparation Transfer about 200 mg of Glyceryl Monolinoleate, accurately weighed, to a 5-mL volumetric flask, dissolve in and dilute with tetrahydrofuran to volume, and mix.
Chromatographic system (see Chromatography 621) Prepare as directed in the Assay under Glyceryl Distearate. Chromatograph the Assay preparation, and record the peak responses as directed for Procedure: the relative retention times are about 1.0 for glycerin, 0.86 for monoglycerides, 0.80 for diglycerides, and 0.76 for triglycerides; the resolution, R, between the diglycerides and monoglycerides is not less than 1.0; and the relative standard deviation for replicate injections determined from the monoglycerides peak is not more than 2.0%.
Procedure Inject a volume (about 40 µL) of the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the percentage of monoglycerides, diglycerides, and triglycerides in the portion of Glyceryl Monolinoleate taken by the formula:
100(ri / rs)in which ri is the individual peak response for the monoglycerides, diglycerides, and triglycerides, as appropriate; and rs is the sum of the responses for all of the glyceride peaks.
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USP32NF27 Page 1245Pharmacopeial Forum: Volume No. 30(3) Page 975