Identification—
A:
Thin-Layer Chromatographic Identification Test 
201
—
Test solution:
a solution in methylene chloride containing about 50 mg per mL.
Developing solvent:
a mixture of ether and hexane (70:30).
Spray reagent:
a solution containing 20 mg of rhodamine B in 200 mL 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.
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 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 Monooleate taken by the formula:
500(C/W),
in which
C is as obtained above; and
W is the amount, in mg, of Glyceryl Monooleate taken to prepare the
Test solution: not more than 6.0% of free glycerin is found.
Assay—
Mobile phase:
tetrahydrofuran.
Assay preparation—
Transfer about 200 mg of Glyceryl Monooleate, 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, 0.85 for monoglycerides, 0.79 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 Monooleate 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.
cerides