Sorbitan Monostearate
(sor' bi tan mon'' oh steer' ate).
[Graphic formula same as for Sorbitan Monolaurate, except that R is (C17H35)COO.]
Sorbitan, esters, monooctadecanoate.
Sorbitan monostearate
[1338-41-6].» Sorbitan Monostearate is a partial ester of Stearic Acid with Sorbitol and its mono- and dianhydrides. It yields, upon saponification, not less than 68.0 percent and not more than 76.0 percent of fatty acids, and not less than 27.0 percent and not more than 34.0 percent of polyols (w/w).
Packaging and storage—
Preserve in well-closed containers.
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Identification—
A:
The residue of stearic acid obtained in the Assay for fatty acids has an acid value (see Fats 
401
) between 200 and 215, about 1 g of the residue, accurately weighed, being used, and an iodine value (see Fats and Fixed Oils 401) of not more than 4.
401) between 200 and 215, about 1 g of the residue, accurately weighed, being used, and an iodine value (see Fats and Fixed Oils 401) of not more than 4.
B:
It responds to Identification test B under Sorbitan Monooleate.
Acid value 401:
not more than 10.
401:
not more than 10.
Hydroxyl value 401:
between 235 and 260.
401:
between 235 and 260.
Saponification value 401:
between 147 and 157.
401:
between 147 and 157.
Water, Method I 921:
not more than 1.5%.
921:
not more than 1.5%.
Residue on ignition 281:
not more than 0.5%.
281:
not more than 0.5%.
Heavy metals, Method II 231:
not more than 0.001%.
231:
not more than 0.001%.
Assay for fatty acids—
Transfer about 10 g of Sorbitan Monostearate, accurately weighed, to a 500-mL conical flask, cautiously add 100 mL of alcohol and 3.0 g of potassium hydroxide, and mix. Proceed as directed in the Assay for fatty acids under Sorbitan Monooleate, beginning with “Connect a suitable condenser.”
Assay for polyols—
Proceed with Sorbitan Monostearate as directed for Assay for polyols under Sorbitan Monooleate.
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 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 1964