Diethylene Glycol Stearates
»Diethylene Glycol Stearates is a mixture of diethylene glycol monoesters and diesters of stearic and palmitic acids.It contains not less than 45.0percent of monoesters produced from the condensation of ethylene glycol and stearic acid of vegetable or animal origin.
Packaging and storage—
Preserve in tight containers.Store at room temperature and protect from light,freezing,and excessive heat.
Labeling—
Label it to indicate that it is intended for topical and vaginal use only.
Identification—
A:
It meets the requirements of the test for Melting range.
B:
It meets the requirements of the test for Fatty acid composition.
and 50
Acid value á401ñ:
not more than 4.0,determined on 10.0g.
Iodine value á401ñ:
not more than 3.0.
Saponification value á401ñ:
between 150and 170,determined on 2.0g.
Fatty acid composition á401ñ—
The fatty acid fraction of it contains not less than 40.0%and not more than 60.0%of stearic acid;and the sum of the contents of palmitic and stearic acids,determined as directed in the chapter,is not less than 90.0%.
Total ash á561ñ:
not more than 0.1%,determined on 1.0g.
Limit of free diethylene glycol—
Mobile phase and Chromatographic system—
Proceed as directed in the Assay.
Standard solutions—
Prepare four solutions by dissolving accurately weighed quantities of diethylene glycol in tetrahydrofuran,and diluting each with tetrahydrofuran,as necessary,to obtain solutions having known concentrations of about 0.5,1.0,2.0,and 4.0mg per mL.
Test solution—
Use the Assay preparation,prepared as directed in the Assay.
Procedure—
Separately inject equal volumes (about 40µL)of the Standard solutionsand the Test solutioninto the chromatograph,record the chromatograms,and measure the responses for the diethylene glycol peaks.Plot the diethylene glycol peak responses obtained versus the concentration,in mg per mL,of diethylene glycol in the Standard solutions.From the standard curve so obtained,determine the diethylene glycol concentration,C,in mg per mL,in the Test solution.Calculate the percentage of free diethylene glycol in the portion of Diethylene Glycol Stearates taken by the formula:
500(C/W),
in which Cis as obtained above;and Wis the amount,in mg,of Diethylene Glycol Stearates taken to prepare the Test solution:not more than 8.0%of free diethylene glycol is found.
Assay—
Mobile phase:
tetrahydrofuran.
Assay preparation—
Transfer about 200mg of Diethylene Glycol Stearates,accurately weighed,to a 5-mLvolumetric flask,dissolve in and dilute with tetrahydrofuran to volume,and mix.
Chromatographic system (see Chromatography á621ñ)—
Prepare as directed in the Assay under Ethylene Glycol Stearates.Chromatograph the Assay preparation,and record the peak responses as directed for Procedure:the relative retention times are about 1.0for diethylene glycol,0.84for monoesters,and 0.78for diesters;and the relative standard deviation for replicate injections determined from the monoesters peak is not more than 2.0%.
Procedure—
Inject a volume (about 40µL)of the Assay preparation into the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the percentage content of free fatty acids,E,by the formula:
IA×270/561.1,
in which IAis the acid value,determined in the test for Acid value.Calculate the percentage of monoesters in the portion of Diethylene Glycol Stearates taken by the formula:
[(rM/(rM+rD)](100–D–E),
in which rMis the peak response for the monoesters;rDis the peak response for the diesters;Dis the percentage of free diethylene glycol in the portion of Diethylene Glycol Stearates taken,as determined in the test for Limit of free diethylene glycol;and Eis as defined above.
Auxiliary Information—
Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3000
Pharmacopeial Forum:Volume No.30(3)Page 974
Phone Number:1-301-816-8251